Carnosine as a Neuroprotective Agent?

Carnosine as a neuroprotective agent

Wise Young, Ph.D., M.D.

W. M. Keck Center for Collaborative Neuroscience

Rutgers University, Piscataway, New Jersey 08854



Injury disrupts cells and causes an inrush of calcium ions.  The calcium ions disrupts mitochondria, causing release of oxygen free radicals.  In addition, calcium ions activate many intracellular enzymes that digest the cell, including phospholipases, phosphatases, nucleases, and proteinases. Phospholipases break down membranes, releasing free fatty acids.  One fatty acid, called arachidonic acid, is broken down by an enzyme called cycloxygenase (COX) to produce prostaglandins and leukotrienes.  Prostaglandins cause inflammation.  These biochemical reactions to injury contribute to progressive tissue damage after injury [1].


Many chemicals are antioxidants, including vitamin C and E, glutathione, naloxone (NX), methylprednisolone (MP), and tirilazad mesylate (TM).  In 1990, the Second National Acute Spinal Cord Injury Study (NASCIS 2) [2, 3] compared high-dose MP and NX, finding that MP (30 mg/kg + 5.4 mg/kg/hr x 23 hr) improves motor and sensory recovery significantly more than placebo controls or NX (5.4 mg/kg + 3 mg/kg/hr x 23 hr).  In addition to being an antioxidant, MP is anti-inflammatory. TM is a potent antioxidant.  The NASCIS 3 trial [4, 5] compared methylprednisolone and tirilazad and found that the two drugs had equivalent effects on recovery when started within 3 hours but a 48-hour course of MP was more effective than a 48-hour course of tirilazad or a 24-hour course of MP.  Therefore, the recommended therapy for acute spinal cord injury is a 24-hour course of MP if treatment can be started within 3 hours and a 48-hour course of MP if started between 3-8 hours [6, 7]. 


Carnosine is a natural antioxidant dipeptide composed on the amino acids histidine and alanine.  Carnosine should not be confused carnitine which is an amino acid that is responsible for transport of fatty acids in mitochondria.  Carnosine is found in brain, heart, skin, muscles, kidneys, gut, and other tissues.  It is widely used as a dietary supplement (500 mg per day) and has been suggested to be potentially useful for treating AlzheimerÕs disease [8, 9], autism [10], cataract prevention [11], brain ischemia [12], ParkinsonÕs disease [13], DownÕs syndrome [14], epilepsy [15, 16], schistosomiasis [17], and aging [18-21].  Oral supplements of carnosine significantly increase carnosine levels in skeletal muscles [22].  Intracerebroventricular injections of carnosine suppresses renal sympathetic nerve activity and blood pressure [23].  It also seems to reduce food intake in a dose-dependent fashion when injected intracerebroventricularly [24] 


Early studies suggested that carnosine is an antioxidant.  In 1984, Dupin, et al. [25] reported that carnosine protected frog muscle subjected to ascorbic acid-dependent lipid peroxidation.  Krichevskaia, et al. [26] used homocarnosine (100 mg/kg) to treat animals subjected to hyperbaric oxygen and found that it prevented lipid peroxidation in brains.  Boldyrev [27-32] suggested that carnosine protected membranes and prevented losses of membrane [33]. Kohen, et al. [34] showed that carnosine, homocarnosine, anserine, and other histidine containing peptides trapped peroxyl radicals while Aruoma, et al. [35] found that these peptides trapped hydroxyl radicals.  Babizhayev [36, 37] reported that carnosine chelates metals, hydroxyl and lipid peroxyl radicals.


The antioxidant mechanisms of carnosine, however, have been controversial. Gorbunov & Erin [38] found that carnosine does not interact directly with active free radicals.  Kohen, et al. [39] subsequently reported that copper-carnosine may acts like superoxide dymutase, an enzyme that breaks down superoxide.  Salim-Hanna, et al. [40] found that carnosine protects enzyme activity in tissues.  MacFarlane, et al. [41] found that carnosine are potent pH buffers.  Several investigators [42-44] have reported that zinc-carnosine and other metal-carnosine chelates inhibits lipid peroxidation [45].  Decker, et al., [46] suggested that the main antioxidant mechanism of carnosine is due to copper chelation.  Trombley, et al. [47, 48] suggest that carnosine modulates neuronal activity and synapses.  Severina & Busygonia [49-52] reported that carnosine inhibits guanylate cylase. Snimoniia, et al. [53] and others [54] found that carnosine protects Na/K ATPase.  Prokopieva, et al. [55] showed that carnosine prevents hemolysis of red blood cells but through mechanisms other than antioxidation or pH buffering.  In 1993, Boldyrev [56-59] concluded that the known biological effects of carnosine cannot be explained only by its antioxidant properties.


Many laboratories reported that carnosine has a variety of beneficial effects on cells and tissues [19, 60-65], including pheochromocytoma [66, 67], heart [68-76], intestines [77], liver [78], skeletal muscles [79, 80].  It appears to prevent cataract formation [81].  Reeve, et al. [82] found that carnosine potentiated immune reactions.  Carnosine also retards senescence of cultured human fibroblasts [83].  Shohami, et al. [84] showed that closed head injury induces whole body oxidative stress that reduced a variety of putative tissue antioxidants, including carnosine. 


Carnosine is present in the central nervous system.  Early studies showed that mouse olfactory bulb bound L-carnosine [85].  Hipkiss [64] proposed that carnosine is a naturally occurring suppressor of oxidative damage in olfactory neurons. De Marchis, et al. [86] found carnosine in mature olfactory receptor neurons, a subset of glial cells, and neural progenitor cells in rat brain. Carnitine is also present in olfactory neurons [47] and visual system [87]. Hoffman, et al. [88] found that rat oligodendroglial cells made carnosine and astrocytes took up carnitine.  Baslow, et al. [89] showed that carnosine is synthesized in macroglia and ependymal cells [90] that may not be able to hydrolyze them and therefore releases them [91]. Sunderman, et al. [92] proposed that carnosine may protect olfactory neurons by complexing metals (e.g. Al, Bi, Cu, Mn, Zn).  Interestingly, anti-epileptic drugs topiramate [15, 93], gabapentin [94], vigabatrin [95, 96] increase homocarnosine levels in human brain.  Homocarnosine levels are related to GABA [97].


Despite the abundance of data suggesting that carnosine and related compounds have antioxidant properties and cellular protective effects, several investigators have suggestd that carnosine is an endogenous neuroprotector [12], relatively little data is available concerning its use as a neuroprotective agent. Pubill, et al. [98] reported that carnosine prevents methamphetamine-induced gliosis.  Gallant, et al. [99] gave rats dietary carosine and found that it reduced mortality and improved behavioral recovery of rats subjected to common carotid artery occlusion. Carnosine, surprisingly, has not been tested in any model of spinal cord injury, whether chronic or acute.


References Cited


1.      Hall ED and Springer JE (2004). Neuroprotection and Acute Spinal Cord Injury: A Reappraisal. Neurorx. 1: 80-100. Spinal Cord and Brain Injury Research Center, University of Kentucky Chandler Medical Center, Lexington, Kentucky 40536. It has long been recognized that much of the post-traumatic degeneration of the spinal cord following injury is caused by a multi-factorial secondary injury process that occurs during the first minutes, hours, and days after spinal cord injury (SCI). A key biochemical event in that process is reactive oxygen-induced lipid peroxidation (LP). In 1990 the results of the Second National Acute Spinal Cord Injury Study (NASCIS II) were published, which showed that the administration of a high-dose regimen of the glucocorticoid steroid methylprednisolone (MP), which had been previously shown to inhibit post-traumatic LP in animal models of SCI, could improve neurological recovery in spinal-cord-injured humans. This resulted in the registration of high-dose MP for acute SCI in several countries, although not in the U.S. Nevertheless, this treatment quickly became the standard of care for acute SCI since the drug was already on the U.S. market for many other indications. Subsequently, it was demonstrated that the non-glucocorticoid 21-aminosteroid tirilazad could duplicate the antioxidant neuroprotective efficacy of MP in SCI models, and evidence of human efficacy was obtained in a third NASCIS trial (NASCIS III). In recent years, the use of high-dose MP in acute SCI has become controversial largely on the basis of the risk of serious adverse effects versus what is perceived to be on average a modest neurological benefit. The opiate receptor antagonist naloxone was also tested in NASCIS II based upon the demonstration of its beneficial effects in SCI models. Although it did not a significant overall effect, some evidence of efficacy was seen in incomplete (i.e., paretic) patients. The monosialoganglioside GM1 has also been examined in a recently completed clinical trial in which the patients first received high-dose MP treatment. However, GM1 failed to show any evidence of a significant enhancement in the extent of neurological recovery over the level afforded by MP therapy alone. The present paper reviews the past development of MP, naloxone, tirilazad, and GM1 for acute SCI, the ongoing MP-SCI controversy, identifies the regulatory complications involved in future SCI drug development, and suggests some promising neuroprotective approaches that could either replace or be used in combination with high-dose MP.


2.      Bracken MB (1991). Treatment of acute spinal cord injury with methylprednisolone: results of a multicenter, randomized clinical trial. J Neurotrauma. 8 Suppl 1: S47-50; discussion S51-2. Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, Connecticut. Although some evidence of neurological improvement with naloxone exists in this trial, the improvement was never significantly better than that seen for placebo. Methylprednisolone (MP) was effective in reducing some of the permanent paralysis after acute spinal cord injury at the doses studied, but only when treatment began within 8 h after injury. There is currently no support for the administration of higher or lower doses of the drug and an apparent contraindication to initiating administration of MP at any dose more than 8 h after injury.


3.      Bracken MB, Shepard MJ, Collins WF, Holford TR, Young W, Baskin DS, Eisenberg HM, Flamm E, Leo-Summers L, Maroon J and et al. (1990). A randomized, controlled trial of methylprednisolone or naloxone in the treatment of acute spinal-cord injury. Results of the Second National Acute Spinal Cord Injury Study. N Engl J Med. 322: 1405-11. Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, CT 06510. Studies in animals indicate that methylprednisolone and naloxone are both potentially beneficial in acute spinal-cord injury, but whether any treatment is clinically effective remains uncertain. We evaluated the efficacy and safety of methylprednisolone and naloxone in a multicenter randomized, double-blind, placebo-controlled trial in patients with acute spinal-cord injury, 95 percent of whom were treated within 14 hours of injury. Methylprednisolone was given to 162 patients as a bolus of 30 mg per kilogram of body weight, followed by infusion at 5.4 mg per kilogram per hour for 23 hours. Naloxone was given to 154 patients as a bolus of 5.4 mg per kilogram, followed by infusion at 4.0 mg per kilogram per hour for 23 hours. Placebos were given to 171 patients by bolus and infusion. Motor and sensory functions were assessed by systematic neurological examination on admission and six weeks and six months after injury. After six months the patients who were treated with methylprednisolone within eight hours of their injury had significant improvement as compared with those given placebo in motor function (neurologic change scores of 16.0 and 11.2, respectively; P = 0.03) and sensation to pinprick (change scores of 11.4 and 6.6; P = 0.02) and touch (change scores, 8.9 and 4.3; P = 0.03). Benefit from methylprednisolone was seen in patients whose injuries were initially evaluated as neurologically complete, as well as in those believed to have incomplete lesions. The patients treated with naloxone, or with methylprednisolone more than eight hours after their injury, did not differ in their neurologic outcomes from those given placebo. Mortality and major morbidity were similar in all three groups. We conclude that in patients with acute spinal-cord injury, treatment with methylprednisolone in the dose used in this study improves neurologic recovery when the medication is given in the first eight hours. We also conclude that treatment with naloxone in the dose used in this study does not improve neurologic recovery after acute spinal-cord injury.


4.      Bracken MB, Shepard MJ, Holford TR, Leo-Summers L, Aldrich EF, Fazl M, Fehlings M, Herr DL, Hitchon PW, Marshall LF, Nockels RP, Pascale V, Perot PL, Jr., Piepmeier J, Sonntag VK, Wagner F, Wilberger JE, Winn HR and Young W (1997). Administration of methylprednisolone for 24 or 48 hours or tirilazad mesylate for 48 hours in the treatment of acute spinal cord injury. Results of the Third National Acute Spinal Cord Injury Randomized Controlled Trial. National Acute Spinal Cord Injury Study. JAMA. 277: 1597-604. OBJECTIVE: To compare the efficacy of methylprednisolone administered for 24 hours with methyprednisolone administered for 48 hours or tirilazad mesylate administered for 48 hours in patients with acute spinal cord injury. DESIGN: Double-blind, randomized clinical trial. SETTING: Sixteen acute spinal cord injury centers in North America. PATIENTS: A total of 499 patients with acute spinal cord injury diagnosed in National Acute Spinal Cord Injury Study (NASCIS) centers within 8 hours of injury. INTERVENTION: All patients received an intravenous bolus of methylprednisolone (30 mg/kg) before randomization. Patients in the 24-hour regimen group (n=166) received a methylprednisolone infusion of 5.4 mg/kg per hour for 24 hours, those in the 48-hour regimen group (n=167) received a methylprednisolone infusion of 5.4 mg/kg per hour for 48 hours, and those in the tirilazad group (n=166) received a 2.5 mg/kg bolus infusion of tirilazad mesylate every 6 hours for 48 hours. MAIN OUTCOME MEASURES: Motor function change between initial presentation and at 6 weeks and 6 months after injury, and change in Functional Independence Measure (FIM) assessed at 6 weeks and 6 months. RESULTS: Compared with patients treated with methylprednisolone for 24 hours, those treated with methylprednisolone for 48 hours showed improved motor recovery at 6 weeks (P=.09) and 6 months (P=.07) after injury. The effect of the 48-hour methylprednisolone regimen was significant at 6 weeks (P=.04) and 6 months (P=.01) among patients whose therapy was initiated 3 to 8 hours after injury. Patients who received the 48-hour regimen and who started treatment at 3 to 8 hours were more likely to improve 1 full neurologic grade (P=.03) at 6 months, to show more improvement in 6-month FIM (P=.08), and to have more severe sepsis and severe pneumonia than patients in the 24-hour methylprednisolone group and the tirilazad group, but other complications and mortality (P=.97) were similar. Patients treated with tirilazad for 48 hours showed motor recovery rates equivalent to patients who received methylprednisolone for 24 hours. CONCLUSIONS: Patients with acute spinal cord injury who receive methylprednisolone within 3 hours of injury should be maintained on the treatment regimen for 24 hours. When methylprednisolone is initiated 3 to 8 hours after injury, patients should be maintained on steroid therapy for 48 hours.


5.      Bracken MB, Shepard MJ, Holford TR, Leo-Summers L, Aldrich EF, Fazl M, Fehlings MG, Herr DL, Hitchon PW, Marshall LF, Nockels RP, Pascale V, Perot PL, Jr., Piepmeier J, Sonntag VK, Wagner F, Wilberger JE, Winn HR and Young W (1998). Methylprednisolone or tirilazad mesylate administration after acute spinal cord injury: 1-year follow up. Results of the third National Acute Spinal Cord Injury randomized controlled trial. J Neurosurg. 89: 699-706. Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, Connecticut 06520-8034, USA. OBJECT: A randomized double-blind clinical trial was conducted to compare neurological and functional recovery and morbidity and mortality rates 1 year after acute spinal cord injury in patients who had received a standard 24-hour methylprednisolone regimen (24MP) with those in whom an identical MP regimen had been delivered for 48 hours (48MP) or those who had received a 48-hour tirilazad mesylate (48TM) regimen. METHODS: Patients for whom treatment was initiated within 3 hours of injury showed equal neurological and functional recovery in all three treatment groups. Patients for whom treatment was delayed more than 3 hours experienced diminished motor function recovery in the 24MP group, but those in the 48MP group showed greater 1-year motor recovery (recovery scores of 13.7 and 19, respectively, p=0.053). A greater percentage of patients improving three or more neurological grades was also observed in the 48MP group (p=0.073). In general, patients treated with 48TM recovered equally when compared with those who received 24MP treatments. A corresponding recovery in self care and sphincter control was seen but was not statistically significant. Mortality and morbidity rates at 1 year were similar in all groups. CONCLUSIONS: For patients in whom MP therapy is initiated within 3 hours of injury, 24-hour maintenance is appropriate. Patients starting therapy 3 to 8 hours after injury should be maintained on the regimen for 48 hours unless there are complicating medical factors.


6.      Bracken MB (2001). Methylprednisolone and acute spinal cord injury: an update of the randomized evidence. Spine. 26: S47-54. Department of Epidemiology, Yale University School of Medicine, 60 College Street, New Haven, Connecticut 06520, USA. OBJECTIVES: Randomized trials are widely recognized as providing the most reliable evidence for assessing efficacy and safety of therapeutic interventions. This evidence base is used to evaluate the current status of methylprednisolone (MPSS) in the early treatment of acute spinal cord injury. METHODS: Medline, CINAHL, and other specified databases were searched for MeSH headings "methylprednisolone and acute spinal cord injury." The Cochrane Library and an existing systematic review on the topic were also searched. RESULTS: Five randomized controlled trials were identified that evaluated high-dose MPSS for acute spinal cord injury. Three trials by the NASCIS group were of high methodologic quality, and a Japanese and French trial of moderate to low, methodologic quality. Meta-analysis of the final result of three trials comparing 24-hour high-dose MPSS with placebo or no therapy indicates an average unilateral 4.1 motor function score improvement (95% confidence interval 0.6-7.6, P = 0.02) in patients treated with MPSS. This neurologic recovery is likely to be correlated with improved functional recovery in some patients. The safety of this regimen of MPSS is evident from the spinal cord injury trials and a systematic review of 51 surgical trials of high-dose MPSS. CONCLUSION: High-dose MPSS given within 8 hours of acute spinal cord injury is a safe and modestly effective therapy that may result in important clinical recovery for some patients. Further trials are needed to identify superior pharmacologic therapies and to test drugs that may sequentially influence the postinjury cascade.


7.      Lammertse DP (2004). Update on pharmaceutical trials in acute spinal cord injury. J Spinal Cord Med. 27: 319-25. Craig Hospital, Englewood, Colorado 80113-2811, USA. OBJECTIVE: To review the major pharmacological trials in acute spinal cord injury (SCI) that have been conducted over the past 25 years. METHODS: Review article. RESULTS: The publication of the first National Acute Spinal Cord Injury (NASCIS) trial in 1984 ushered in the era of pharmacological trials of therapies intended to improve neurologic outcome in acute SCI. Subsequent trials of methylprednisolone sodium succinate (MPSS) and GM-1 have added to the evidence basis that informs the current management practices for acute SCI. CONCLUSION: The last 50 years have seen a conceptual shift from the pessimism of the past to a cautious optimism that the meager prognosis for neurologic recovery in acute SCI will yield to the progress of medical science. Major advances in the understanding of primary and secondary injury mechanisms have led to the preclinical study of many promising pharmacological therapies, all with the goal of improving neurologic outcome. A few of these drugs have stood the test of animal model experiments and have made it to the forum of human clinical trials. The NASCIS trials of methylprednisolone have been acknowledged widely as the first human studies to claim improved neurologic outcome. Although the results of these trials remain controversial, the MPSS therapy that they reported has been adopted widely by clinicians around the world as the best currently available, even if not a consensus "standard of care." Clearly, the challenge for medical science remains. The search for effective treatment has only begun.


8.      Hobart LJ, Seibel I, Yeargans GS and Seidler NW (2004). Anti-crosslinking properties of carnosine: significance of histidine. Life Sci. 75: 1379-89. Department of Biochemistry, University of Health Sciences, 1750 Independence Avenue, Kansas City, MO 64106-1453, USA. Carnosine, a histidine-containing dipeptide, is a potential treatment for Alzheimer's disease. There is evidence that carnosine prevents oxidation and glycation, both of which contribute to the crosslinking of proteins; and protein crosslinking promotes beta-amyloid plaque formation. It was previously shown that carnosine has anti-crosslinking activity, but it is not known which of the chemical constituents are responsible. We tested the individual amino acids in carnosine (beta-alanine, histidine) as well as modified forms of histidine (alpha-acetyl-histidine, 1-methyl-histidine) and methylated carnosine (anserine) using glycation-induced crosslinking of cytosolic aspartate aminotransferase as our model. beta-Alanine showed anti-crosslinking activity but less than that of carnosine, suggesting that the beta-amino group is required in preventing protein crosslinking. Interestingly, histidine, which has both alpha-amino and imidazolium groups, was more effective than carnosine. Acetylation of histidine's alpha-amino group or methylation of its imidazolium group abolished anti-crosslinking activity. Furthermore, methylation of carnosine's imidazolium group decreased its anti-crosslinking activity. The results suggest that histidine is the representative structure for an anti-crosslinking agent, containing the necessary functional groups for optimal protection against crosslinking agents. We propose that the imidazolium group of histidine or carnosine may stabilize adducts formed at the primary amino group.


9.      Dukic-Stefanovic S, Schinzel R, Riederer P and Munch G (2001). AGES in brain ageing: AGE-inhibitors as neuroprotective and anti-dementia drugs? Biogerontology. 2: 19-34. Physiological Chemistry I, Biocenter, University of Wurzburg, Germany. In Alzheimer's disease, age-related cellular changes such as compromised energy production and increased radical formation are worsened by the presence of AGEs as additional, AD specific stress factors. Intracellular AGEs (most likely derived from methylglyoxal) crosslink cytoskeletal proteins and render them insoluble. These aggregates inhibit cellular functions including transport processes and contribute to neuronal dysfunction and death. Extracellular AGEs, which accumulate in ageing tissue (but most prominently on long-lived protein deposits like the senile plaques) exert chronic oxidative stress on neurons. In addition, they activate glial cells to produce free radicals (superoxide and NO) and neurotoxic cytokines such as TNF-alpha. Drugs, which inhibit the formation of AGEs by specific chemical mechanisms (AGE-inhibitors), including aminoguanidine, carnosine, tenilsetam, OPB-9195 and pyridoxamine, attenuate the development of (AGE-mediated) diabetic complications. Assuming that 'carbonyl stress' contributes significantly to the progression of Alzheimer's disease, AGE-inhibitors might also become interesting novel therapeutic drugs for treatment of AD.


10.    Chez MG, Buchanan CP, Aimonovitch MC, Becker M, Schaefer K, Black C and Komen J (2002). Double-blind, placebo-controlled study of L-carnosine supplementation in children with autistic spectrum disorders. J Child Neurol. 17: 833-7. Research Division, Autism and Epilepsy Specialty Services of Illinois, Ltd, Lake Bluff, IL 60044, USA. L-Carnosine, a dipeptide, can enhance frontal lobe function or be neuroprotective. It can also correlate with gamma-aminobutyric acid (GABA)-homocarnosine interaction, with possible anticonvulsive effects. We investigated 31 children with autistic spectrum disorders in an 8-week, double-blinded study to determine if 800 mg L-carnosine daily would result in observable changes versus placebo. Outcome measures were the Childhood Autism Rating Scale, the Gilliam Autism Rating Scale, the Expressive and Receptive One-Word Picture Vocabulary tests, and Clinical Global Impressions of Change. Children on placebo did not show statistically significant changes. After 8 weeks on L-carnosine, children showed statistically significant improvements on the Gilliam Autism Rating Scale (total score and the Behavior, Socialization, and Communication subscales) and the Receptive One-Word Picture Vocabulary test (all P < .05). Improved trends were noted on other outcome measures. Although the mechanism of action of L-carnosine is not well understood, it may enhance neurologic function, perhaps in the enterorhinal or temporal cortex.


11.    Babizhayev MA, Deyev AI, Yermakova VN, Brikman IV and Bours J (2004). Lipid peroxidation and cataracts: N-acetylcarnosine as a therapeutic tool to manage age-related cataracts in human and in canine eyes. Drugs R D. 5: 125-39. Innovative Vision Products Inc., County of New Castle, Delaware, USA. Cataract formation represents a serious problem in the elderly, with approximately 25% of the population aged >65 years and about 50% aged >80 years experiencing a serious loss of vision as a result of this condition. Not only do cataracts diminish quality of life, they also impose a severe strain on global healthcare budgets. In the US, 43% of all visits to ophthalmologists by Medicare patients are associated with cataract. Surgery represents the standard treatment of this condition, and 1.35 million cataract operations are performed annually in the US, costing 3.5 billion US dollars (year of costing, 1998). Unfortunately, the costs of surgical treatment and the fact that the number of patients exceeds surgical capacities result in many patients being blinded by cataracts worldwide. This situation is particularly serious in developing countries; worldwide 17 million people are blind because of cataract formation, and the problem will grow in parallel with aging of the population. In any event, surgical removal of cataracts may not represent the optimal solution. Although generally recognised as being one of the safest operations, there is a significant complication rate associated with this surgical procedure. Opacification of the posterior lens capsule occurs in 30-50% of patients within 2 years of cataract removal and requires laser treatment, a further 0.8% experience retinal detachments, approximately 1% are rehospitalised for corneal problems, and about 0.1% develop endophthalmitis. Although the risks are small, the large number of procedures performed means that 26,000 individuals develop serious complications as a result of cataract surgery annually in the US alone. Thus, risk and cost factors drive the investigation of pharmaceutical approaches to the maintenance of lens transparency. The role of free radical-induced lipid oxidation in the development of cataracts has been identified. Initial stages of cataract are characterised by the accumulation of primary (diene conjugates, cetodienes) lipid peroxidation (LPO) products, while in later stages there is a prevalence of LPO fluorescent end-products. A reliable increase in oxiproducts of fatty acyl content of lenticular lipids was shown by a direct gas chromatography technique producing fatty acid fluorine-substituted derivatives. The lens opacity degree correlates with the level of the LPO fluorescent end-product accumulation in its tissue, accompanied by sulfhydryl group oxidation of lens proteins due to a decrease of reduced glutathione concentration in the lens. The injection of LPO products into the vitreous has been shown to induce cataract. It is concluded that peroxide damage of the lens fibre membranes may be the initial cause of cataract development. N-acetylcarnosine (as the ophthalmic drug Can-C), has been found to be suitable for the nonsurgical prevention and treatment of age-related cataracts. This molecule protects the crystalline lens from oxidative stress-induced damage, and in a recent clinical trial it was shown to produce an effective, safe and long-term improvement in sight. When administered topically to the eye in the form of Can-C, N-acetylcarnosine functions as a time-release prodrug form of L-carnosine resistant to hydrolysis with carnosinase. N-acetylcarnosine has potential as an in vivo universal antioxidant because of its ability to protect against oxidative stress in the lipid phase of biological cellular membranes and in the aqueous environment by a gradual intraocular turnover into L-carnosine. In our study the clinical effects of a topical solution of N-acetylcarnosine (Can-C) on lens opacities were examined in patients with cataracts and in canines with age-related cataracts. These data showed that N-acetylcarnosine is effective in the management of age-related cataract reversal and prevention both in human and in canine eyes.


12.    Stvolinsky SL, Kukley ML, Dobrota D, Matejovicova M, Tkac I and Boldyrev AA (1999). Carnosine: an endogenous neuroprotector in the ischemic brain. Cell Mol Neurobiol. 19: 45-56. Institute of Neurology, Russian Academy of Medical Sciences, Moscow, Russia. 1. The biological effects of carnosine, a natural hydrophilic neuropeptide, on the reactive oxygen species (ROS) pathological generation are reviewed. 2. We describe direct antioxidant action observed in the in vitro experiments. 3. Carnosine was found to effect metabolism indirectly. These effects are reflected in ROS turnover regulation and lipid peroxidation (LPO) processes. 4. During brain ischemia carnosine acts as a neuroprotector, contributing to better cerebral blood flow restoration, electroencephalography (EEG) normalization, decreased lactate accumulation, and enzymatic protection against ROS. 5. The data presented demonstrate that carnosine is a specific regulator of essential metabolic pathways in neurons supporting brain homeostasis under unfavorable conditions.


13.    Kang JH and Kim KS (2003). Enhanced oligomerization of the alpha-synuclein mutant by the Cu,Zn-superoxide dismutase and hydrogen peroxide system. Mol Cells. 15: 87-93. Department of Genetic Engineering, Chongju University, Chongju 360-764, Korea. The alpha-synuclein is a major component of Lewy bodies that are found in the brains of patients with Parkinson's disease (PD). Also, two point mutations in this protein, A53T and A30P, are associated with rare familial forms of the disease. We investigated whether there are differences in the Cu,Zn-SOD and hydrogen peroxide system mediated-protein modification between the wild-type and mutant alpha-synucleins. When alpha-synuclein was incubated with both Cu,Zn-SOD and H2O2, then the amount of A53T mutant oligomerization increased relative to that of the wild-type protein. This process was inhibited by radical scavenger, spin-trapping agent, and copper chelator. These results suggest that the oligomerization of alpha-synuclein is mediated by the generation of the hydroxyl radical through the metal-catalyzed reaction. The dityrosine formation of the A53T mutant protein was enhanced relative to that of the wild-type protein. Antioxidant molecules, carnosine, and anserine effectively inhibited the wild-type and mutant proteins' oligomerization. Therefore, these compounds may be explored as potential therapeutic agents for PD patients. The present experiments, in part, may provide an explanation for the association between PD and the alpha-synuclein mutant.


14.    Thiel R and Fowkes SW (2005). Can cognitive deterioration associated with Down syndrome be reduced? Med Hypotheses. 64: 524-32. Center for Natural Health Research, Down Syndrome-Epilepsy Foundation, 1248 E. Grand Avenue, Suite A, Arroyo Grande, CA 93420, USA. Individuals with Down syndrome have signs of possible brain damage prior to birth. In addition to slowed and reduced mental development, they are much more likely to have cognitive deterioration and develop dementia at an earlier age than individuals without Down syndrome. Some of the cognitive impairments are likely due to post-natal hydrogen peroxide-mediated oxidative stress caused by overexpression of the superoxide dismutase (SOD-1) gene, which is located on the triplicated 21st chromosome and known to be 50% overexpressed. However, some of this disability may also be due to early accumulation of advanced protein glycation end-products, which may play an adverse role in prenatal and postnatal brain development. This paper suggests that essential nutrients such as folate, vitamin B6, vitamin C, vitamin E, selenium, and zinc, as well as alpha-lipoic acid and carnosine may possibly be partially preventive. Acetyl-l-carnitine, aminoguanidine, cysteine, and N-acetylcysteine are also discussed, but have possible safety concerns for this population. This paper hypothesizes that nutritional factors begun prenatally, in early infancy, or later may prevent or delay the onset of dementia in the Down syndrome population. Further examination of these data may provide insights into nutritional, metabolic and pharmacological treatments for dementias of many kinds. As the Down syndrome population may be the largest identifiable group at increased risk for developing dementia, clinical research to verify the possible validity of the prophylactic use of anti-glycation nutrients should be performed. Such research might also help those with glycation complications associated with diabetes or Alzheimer's.


15.    Petroff OA, Hyder F, Rothman DL and Mattson RH (2001). Topiramate rapidly raises brain GABA in epilepsy patients. Epilepsia. 42: 543-8. Department of Neurology, Yale University, New Haven, Connecticut 06520-8018, USA. PURPOSE: The short- and long-term pharmacodynamic effects of topiramate (TPM) on brain gammay-aminobutyric acid (GABA) metabolism were studied in patients with complex partial seizures. METHODS: In vivo measurements of GABA, homocarnosine, and pyrrolidinone were made of a 14-cc volume in the occipital cortex using 1H spectroscopy with a 2.1-Tesla magnetic resonance spectrometer and an 8-cm surface coil. Fifteen patients (four men) were studied serially after the first, oral dose (100 mg) of TPM. RESULTS: The first dose of TPM increased brain GABA within 1 h. Within 4 h, GABA was increased by 0.9 mM (95% CI, 0.7-1.1). Brain GABA remained elevated for > or =24 h. Pyrrolidinone and homocarnosine increased slowly during the first day. Daily TPM therapy (median, 300 mg; range, 200-500) increased GABA (0.3 mM; 95% CI, 0.1-0.5), homocarnosine (0.4 mM; 95% CI, 0.3-0.5), and pyrrolidinone (0.15 mM; 95% CI, 0.10-0.19), compared with levels before TPM. There was no dose response evident with daily TPM doses of 200-500 mg. CONCLUSIONS: TPM promptly elevates brain GABA and presumably offers partial protection against further seizures within hours of the first oral dose. Patients may expect to experience the effects of increased homocarnosine and pyrrolidinone within 24 h.


16.    Petroff OA, Hyder F, Rothman DL and Mattson RH (2001). Homocarnosine and seizure control in juvenile myoclonic epilepsy and complex partial seizures. Neurology. 56: 709-15. Department of Neurology, Yale University, New Haven, CT 06520-8018, USA. OBJECTIVE: To assess the relationship between seizure control and gamma-aminobutyric acid (GABA), homocarnosine, and pyrrolidinone levels in the visual cortex of patients with epilepsy taking valproate or lamotrigine. Previous studies suggested that poor seizure control was associated with low GABA and homocarnosine levels. METHODS: In vivo measurements of GABA, homocarnosine, and pyrrolidinone were made in a 14-cm(3) volume of the occipital cortex using (1)H spectroscopy with a 2.1-Tesla MR spectrometer and an 8-cm surface coil. Twenty-six adults (eight men) taking valproate or lamotrigine were recruited; 12 had complex partial seizures (CPS) and 14 had juvenile myoclonic epilepsy (JME). RESULTS: Median homocarnosine levels were normal for patients with JME and below normal for patients with CPS. Better seizure control was associated with higher homocarnosine levels for both groups. Median GABA was below normal for patients with JME, lower than for patients with CPS. Brain GABA was lowest in patients with JME even when seizure control was excellent. Pyrrolidinone levels were above normal in almost all patients with JME. CONCLUSIONS: Low GABA levels are associated with poor seizure control in patients with CPS, but not in JME. Higher homocarnosine levels are associated with better seizure control in both types of epilepsy.


17.    Soliman K, El-Ansary A and Mohamed AM (2001). Effect of carnosine administration on metabolic parameters in bilharzia-infected hamsters. Comp Biochem Physiol B Biochem Mol Biol. 129: 157-64. Biochemistry Department, Faculty of Medicine, Cairo University, Cairo, Egypt. Carnosine is a naturally occurring dipeptide (beta-alanyl-L-histidine) found in muscles, brain and other tissues. This study was designed to test the ability of carnosine to offset metabolic disturbances induced by Schistosoma mansoni parasitism. Results indicate that parasitic infection caused elevation of liver weight/body weight in S. mansoni-infected hamsters, induced lipid peroxidation and reduced glycogen levels. Moreover, adenylate energy charge (AEC) and ATP/ADP and ATP/AMP concentration ratios were markedly lower in infected hamsters. Administration of carnosine (10 mg/day) for 15 days concurrent with infection effectively reduced worm burden and egg count. Administration of carnosine 2 and 4 weeks post-exposure only partially ameliorated the S. mansoni effects on metabolism. Carnosine treatment also normalized most of the parameters measured, including glycogen repletion, the antioxidant status and AEC. These finding support the use of carnosine for possible intervention in schistosomiasis.


18.    Ferrari CK (2004). Functional foods, herbs and nutraceuticals: towards biochemical mechanisms of healthy aging. Biogerontology. 5: 275-89. Department of Nutrition, Faculty of Public Health, University of Sao Paulo, Av Dr. Arnaldo, 715, 2 andar, 01246-904, Sao Paulo (SP), Brazil. Aging is associated with mitochondrial dysfunctions, which trigger membrane leakage, release of reactive species from oxygen and nitrogen and subsequent induction of peroxidative reactions that result in biomolecules' damaging and releasing of metals with amplification of free radicals discharge. Free radicals induce neuronal cell death increasing tissue loss, which could be associated with memory detriment. These pathological events are involved in cardiovascular, neurodegenerative and carcinogenic processes. Dietary bioactive compounds from different functional foods, herbs and nutraceuticals (ginseng, ginkgo, nuts, grains, tomato, soy phytoestrogens, curcumin, melatonin, polyphenols, antioxidant vitamins, carnitine, carnosine, ubiquinone, etc.) can ameliorate or even prevent diseases. Protection from chronic diseases of aging involves antioxidant activities, mitochondrial stabilizing functions, metal chelating activities, inhibition of apoptosis of vital cells, and induction of cancer cell apoptosis. Functional foods and nutraceuticals constitute a great promise to improve health and prevent aging-related chronic diseases.


19.    Hipkiss AR, Brownson C and Carrier MJ (2001). Carnosine, the anti-ageing, anti-oxidant dipeptide, may react with protein carbonyl groups. Mech Ageing Dev. 122: 1431-45. Division of Biomolecular Sciences, GKT School of Biomedical Sciences, King's College London, Guy's Campus, London Bridge, London SE1 1UL, UK. Carnosine (beta-alanyl-L-histidine) is a physiological dipeptide which can delay ageing and rejuvenate senescent cultured human fibroblasts. Carnosine's anti-oxidant, free radical- and metal ion-scavenging activities cannot adequately explain these effects. Previous studies showed that carnosine reacts with small carbonyl compounds (aldehydes and ketones) and protects macromolecules against their cross-linking actions. Ageing is associated with accumulation of carbonyl groups on proteins. We consider here whether carnosine reacts with protein carbonyl groups. Our evidence indicates that carnosine can react non-enzymically with protein carbonyl groups, a process termed 'carnosinylation'. We propose that similar reactions could occur in cultured fibroblasts and in vivo. A preliminary experiment suggesting that carnosine is effective in vivo is presented; it suppressed diabetes-associated increase in blood pressure in fructose-fed rats, an observation consistent with carnosine's anti-glycating actions. We speculate that: (i) carnosine's apparent anti-ageing actions result, partly, from its ability to react with carbonyl groups on glycated/oxidised proteins and other molecules; (ii) this reaction, termed 'carnosinylation,' inhibits cross-linking of glycoxidised proteins to normal macromolecules; and (iii) carnosinylation could affect the fate of glycoxidised polypeptides.


20.    Boldyrev AA, Yuneva MO, Sorokina EV, Kramarenko GG, Fedorova TN, Konovalova GG and Lankin VZ (2001). Antioxidant systems in tissues of senescence accelerated mice. Biochemistry (Mosc). 66: 1157-63. Department of Biochemistry, School of Biology, Lomonosov Moscow State University, Moscow, 119899, Russia. Significant decrease in the level of lipid antioxidants (measured from the kinetics of the induced chemiluminescence in brain homogenate) and of the hydrophilic antioxidant carnosine as well was observed in the brain of 14-16-month-old mice of SAMP1 line, which is characterized by accelerated accumulation of senile features, in comparison with the control line SAMR1. In the brain of SAMP1 animals the activity of cytosolic Cu/Zn-containing superoxide dismutase (SOD) was reduced, while the activity of membrane-bound Mn-SOD was at an extremely low level. The activity of glutathione-dependent enzymes (glutathione peroxidase, glutathione reductase, and glutathione transferase) did not differ in the brain of SAMP1 and SAMR1 animals, and catalase activity was similarly low in both cases. At the same time, excess concentration of excitotoxic compounds, significantly exceeding that for the control line, was determined in the brain and blood of SAMP1 animals. The activity of glutathione enzymes in liver and heart as well as the activity of cytosolic Cu/Zn-SOD in liver did not differ in the two studied lines, while the activity of erythrocyte glutathione peroxidase was slightly increased, and the activity of liver catalase and erythrocyte Cu/Zn-SOD was significantly decreased for SAMP1 compared with SAMR1. The results demonstrate that the accelerated ageing of SAMP1 animals is connected to a significant extent with the decreased efficiency of the systems utilizing reactive oxygen species (ROS) in tissues.


21.    Stuerenburg HJ (2000). The roles of carnosine in aging of skeletal muscle and in neuromuscular diseases. Biochemistry (Mosc). 65: 862-5. Neurological Department, University Hospital Hamburg-Eppendorf, 20246 Hamburg, Germany. Skeletal muscles undergo specific alterations that are related to the aging process. The incidence of several neuromuscular diseases (e.g., amyotrophic lateral sclerosis (ALS), myasthenia gravis, polymyositis, drug-induced myopathies, late-onset mitochondrial myopathy) is age-related. The increased sensitivity to disease of aging muscle represents an additional age-related negative influence in the presence of existing risk factors (such as a genetic predisposition). The potential significance of carnosine lies on one hand in its possible influence on specific physiological changes in muscle associated with the aging process, and on the other in its effect on oxidative stress and the antioxidative system in specific neuromuscular diseases such as ALS or polymyositis.


22.    Maynard LM, Boissonneault GA, Chow CK and Bruckner GG (2001). High levels of dietary carnosine are associated with increased concentrations of carnosine and histidine in rat soleus muscle. J Nutr. 131: 287-90. Department of Clinical Science/Division of Clinical Nutrition, University of Kentucky, Lexington, Kentucky 40506, USA. The aims of this investigation were to: 1) determine the effect of a moderately high dose of carnosine on muscle concentrations of carnosine, histidine and vitamin E at deficient, minimally adequate and sufficient levels of dietary vitamin E and 2) compare the effects of moderately high and pharmacological doses of carnosine on muscle concentrations of carnosine, histidine and vitamin E when dietary vitamin E is minimally adequate. Muscle concentrations of carnosine, histidine and vitamin E were measured in the lateral gastrocnemius and red and white vastus lateralis; carnosine and histidine concentrations were also measured in soleus muscle. Male Sprague-Dawley rats (n = 12/group) were fed a basal vitamin E-deficient diet supplemented with either 0, 0.001 or 0.01% vitamin E and 0, 0.1 or 1.8% carnosine. After 8 wk, 1.8% carnosine resulted in significant fivefold increases in carnosine and twofold increases in histidine in the soleus muscle (P < or = 0.05). Muscle vitamin E concentrations were not significantly affected by dietary carnosine. Thus, very high levels of dietary carnosine are associated with increases in carnosine and histidine concentrations in rat soleus muscle.


23.    Tanida M, Niijima A, Fukuda Y, Sawai H, Tsuruoka N, Shen J, Yamada S, Kiso Y and Nagai K (2005). Dose-dependent effects of L-carnosine on the renal sympathetic nerve and blood pressure in urethane-anesthetized rats. Am J Physiol Regul Integr Comp Physiol. 288: R447-55. Division of Protein Metabolism, Institute for Protein Research, Osaka University, Osaka, Japan. The physiological function of L-carnosine (beta-alanyl-L-histidine) synthesized in mammalian muscles has been unclear. Previously, we observed that intravenous (i.v.) injection of L-carnosine suppressed renal sympathetic nerve activity (RSNA) in urethane-anesthetized rats, and L-carnosine administered via the diet inhibited the elevation of blood pressure (BP) in deoxycorticosterone acetate salt hypertensive rats. To identify the mechanism, we examined effects of i.v. or intralateral cerebral ventricular (l.c.v.) injection of various doses of L-carnosine on RSNA and BP in urethane-anesthetized rats. Lower doses (1 microg i.v.; 0.01 microg l.c.v.) of L-carnosine significantly suppressed RSNA and BP, whereas higher doses (100 microg i.v.; 10 microg l.c.v.) elevated RSNA and BP. Furthermore, we examined effects of antagonists of histaminergic (H1 and H3) receptors on L-carnosine-induced effects. When peripherally and centrally given, thioperamide, an H3 receptor antagonist, blocked RSNA and BP decreases induced by the lower doses of peripheral L-carnosine, whereas diphenhydramine, an H1 receptor antagonist, inhibited increases induced by the higher doses of peripheral L-carnosine. Moreover, bilateral lesions of the hypothalamic suprachiasmatic nucleus eliminated both effects on RSNA and BP induced by the lower (1 microg) and higher (100 microg) doses of peripheral L-carnosine. These findings suggest that low-dose L-carnosine suppresses and high-dose L-carnosine stimulates RSNA and BP, that the suprachiasmatic nucleus and histaminergic nerve are involved in the activities, and that L-carnosine acts in the brain and possibly other organs.


24.    Tomonaga S, Tachibana T, Takagi T, Saito ES, Zhang R, Denbow DM and Furuse M (2004). Effect of central administration of carnosine and its constituents on behaviors in chicks. Brain Res Bull. 63: 75-82. Laboratory of Advanced Animal and Marine Bioresources, Graduate School of Bioresource and Bioenvironmental Science, Kyushu University, Fukuoka 812-8581, Japan. Even though their contents in the brain are high, the function of brain carnosine and its constituents has not been clarified. Both carnosine and anserine inhibited food intake in a dose dependent fashion when injected intracerebroventricularly. The constituents of carnosine, beta-alanine (beta-Ala) and l-histidine (His), also inhibited food intake, but their effects were weaker than carnosine itself. Co-administration with beta-Ala and His inhibited food intake similar to carnosine, but also altered other behaviors. Injection of carnosine induced hyperactivity and increased plasma corticosterone level, whereas beta-Ala plus His induced hypoactivity manifested as sleep-like behavior. This later effect seemed to be derived from beta-Ala, not His. These results suggest that central carnosine may act in the brain of chicks to regulate brain function and/or behavior in a manner different from its constituents.


25.    Dupin AM, Boldyrev AA, Arkhipenko Iu V and Kagan VE (1984). [Carnosine protection of Ca2+ transport against damage induced by lipid peroxidation]. Biull Eksp Biol Med. 98: 186-8. The authors studied the protective action of carnosine on sarcoplasmic reticulum (SR) membranes from frog skeletal muscles destroyed by ascorbic acid-dependent lipid peroxidation (LPO). It was demonstrated that addition of carnosine to the incubation medium at a concentration of 25 mM sharply decelerated inactivation of Ca-ATPase of SR membranes, maintaining at the same time the coupling of hydrolysing and transport functions of the Ca-pump. When given at the same concentration carnosine inhibited the accumulation of LPO products reacting with 2-thiobarbituric acid. This effect of carnosine was followed by its utilization.


26.    Krichevskaia AA, Bondarenko TI, Makletsova MG and Mikhaleva, II (1985). [Protective effect of the neuropeptide homocarnosine in hyperbaric oxygenation]. Vopr Med Khim. 31: 75-9. Homocarnosine, at a dose of 10 mg per 100 g of animal body mass administered intraperitoneally within 15 min before hyperbaric oxygenation with 0.7 MPa of oxygen, exhibited a protective effect. After administration of the neuropeptide into animals before hyperbaric oxygenation a latent period of oxygen convulsions was increased; content of homocarnosine and gamma-aminobutyric acid (GABA) was maintained at the level found in brain of control animals. In brain tissue of unprotected animals content of homocarnosine and GABA was decreased due to the oxygen treatment. GABA was less effective, its protective dose exceeded 10-fold the dose of homocarnosine. The neuropeptide exhibited antioxidant properties in reactions of lipid peroxidation under normal conditions and in hyperbaric oxygenation in vitro. The antioxidant activity of GABA was distinctly lower as compared with homocarnosine.


27.    Boldyrev AA (1986). [Biological role of histidine-containing dipeptides]. Biokhimiia. 51: 1930-43. The biological role of histidine-containing dipeptides is reviewed. The role of carnosine and anserine in muscle function is discussed from the evolutionary viewpoint. Evidence on the antioxidative effect of carnosine and its protection of biological membranes against lipid peroxidation-induced damages is presented. The effects of presently known natural antioxidative agents and carnosine on lipid peroxidation are compared. Carnosine has been shown to be a more universal protector of membranes as compared to free radical scavengers.


28.    Boldyrev AA, Dupin AM, Bunin A, Babizhaev MA and Severin SE (1987). The antioxidative properties of carnosine, a natural histidine containing dipeptide. Biochem Int. 15: 1105-13. Department of Biochemistry, Moscow State University, USSR. The experimental results suggest that the antioxidative function of carnosine is one of the most important manifestations of its biological role. The ability of carnosine to interact directly with lipid peroxidation products was demonstrated. The effects of carnosine on partial restoration of lens transparency in dog eyes with senile cataract which is known to be caused by lipid peroxidation were demonstrated "in vitro" and "in vivo".


29.    Boldyrev AA, Dupin AM, Pindel EV and Severin SE (1988). Antioxidative properties of histidine-containing dipeptides from skeletal muscles of vertebrates. Comp Biochem Physiol B. 89: 245-50. Department of Biochemistry, School of Biology, Moscow State University, U.S.S.R. 1. Ascorbate-dependent peroxidation of lipid components of biological membranes is inhibited by the natural histidine-containing dipeptides, carnosine and anserine, used at physiological concentrations. 2. Carnosine and anserine exhibit an equal antioxidative activity, whereas the preventing effect of homocarnosine is manifested only at low concentrations of oxidized lipid material. 3. The inhibiting effect of the dipeptides is enhanced either by the rise in the dipeptide concentration or by the decrease in the level of membrane components. 4. Addition of the dipeptides results in a marked decrease in the level of primary molecular products of lipid peroxidation. 5. In this case the optical spectrum of primary molecular products of polyunsaturated fatty acids changes significantly.


30.    Boldyrev AA, Dupin AM, Siambela M and Stvolinsky SL (1988). The level of natural antioxidant glutathione and histidine-containing dipeptides in skeletal muscles of developing chick embryos. Comp Biochem Physiol B. 89: 197-200. Department of Biochemistry, School of Biology, Moscow State University, U.S.S.R. 1. The levels of glutathione and histidine-containing dipeptides in skeletal muscles change in different ways during ontogenesis. 2. The glutathione content in skeletal muscles increases between the 9th and 18th days of embryongenesis--from 0.5 to 2.0 mumol/g of tissue wet wt and then drops to zero in 3-week-old chickens. 3. The level of histidine-containing dipeptides increases throughout the observation period beginning with their appearance on the 14th day in leg muscles and on the 15th day in breast muscles of chicken embryos up to the 21st postnatal day. 4. There is a negative correlation between the antioxidative systems of glutathione and histidine-containing dipeptides in muscle tissue, i.e. dipeptide-rich tissues contain little or no glutathione and vice versa.


31.    Boldyrev AA, Dupin AM, Batrukova MA, Bavykina NI, Korshunova GA and Shvachkin Yu P (1989). A comparative study of synthetic carnosine analogs as antioxidants. Comp Biochem Physiol B. 94: 237-40. School of Biology, M. V. Lomonosov Moscow State University, USSR. 1. The antioxidative activity of carnosine and 16 related compounds, both synthetic and natural, was determined. 2. The antioxidative effect was estimated by the ability of the dipeptides to prevent MDA accumulation in the course of LPO induced in rabbit sarcoplasmic reticulum membranes by the Fe2+ ascorbate system. 3. It was found that the antioxidative effect comparable to that of carnosine was exerted by water-soluble (cyclo-L-histidyl-L-proline) and alcohol-soluble (cyclo-L-histidyl-L-phenilalanine) dipeptides as well as by the histidine-free cyclodipeptides (cyclo-L-tyrosyl-L-proline). 4. However, in contrast to its synthetic analogs, carnosine not only inhibited the LPO, but also diminished the level of products accumulated during membrane lipid peroxidation.


32.    Boldyrev AA and Severin SE (1990). The histidine-containing dipeptides, carnosine and anserine: distribution, properties and biological significance. Adv Enzyme Regul. 30: 175-94. Department of Biochemistry, Moscow State University, U.S.S.R. The biological significance of histidine-containing dipeptides discovered within the composition of nitrogenous extracts of skeletal muscles at the beginning of this century is still open to question. The present investigation is concerned with the analysis of distribution and metabolism of these compounds with special reference to their effects on functional activity of membrane-linked enzymatic systems, stability of cellular membranes, muscle contractibility, etc. The proposed hypothesis on stabilizing properties of carnosine and related substances on biological membranes is based on the ability of the dipeptides to interact with lipid peroxidation products and active oxygen species and to prevent membrane damage. This remarkable antioxidative effect of carnosine reflects the high therapeutic value of this compound as an anti-inflammatory drug and a prominent tool in wound healing.


33.    Guliaeva NV, Dupin AM, Levshina IP, Obidin AB and Boldyrev AA (1989). [Carnosine prevents the activation of free-radical lipid oxidation during stress]. Biull Eksp Biol Med. 107: 144-7. Carnosine (beta-alanyl-L-histidine) injected to intact albino rats (20 mg/kg body weight) induces depletion of lipid peroxidation (LPO) products in brain and blood serum, an increase of superoxide scavenging activity in brain and serum, decrease of cholesterol: phospholipid ratio and increase of easy oxidizable phospholipid portion in brain lipid extracts. After painful stress (footshock during 2 hours) LPO products are accumulated in brain and serum, cholesterol: phospholipid ratio increases and the portion of easy oxidizable phospholipids decreases. Carnosine given before stress prevents LPO activation. Effects of carnosine and stress are not additive: LPO inhibition induced by carnosine is much more in rats subjected to stress.


34.    Kohen R, Yamamoto Y, Cundy KC and Ames BN (1988). Antioxidant activity of carnosine, homocarnosine, and anserine present in muscle and brain. Proc Natl Acad Sci U S A. 85: 3175-9. Department of Biochemistry, University of California, Berkeley 94720. Carnosine, homocarnosine, and anserine are present in high concentrations in the muscle and brain of many animals and humans. However, their exact function is not clear. The antioxidant activity of these compounds has been examined by testing their peroxyl radical-trapping ability at physiological concentrations. Carnosine, homocarnosine, anserine, and other histidine derivatives all showed antioxidant activity. All of these compounds showing peroxyl radical-trapping activity were also electrochemically active as reducing agents in cyclic voltammetric measurements. Furthermore, carnosine inhibited the oxidative hydroxylation of deoxyguanosine induced by ascorbic acid and copper ions. Other roles of carnosine, such as chelation of metal ions, quenching of singlet oxygen, and binding of hydroperoxides, are also discussed. The data suggest a role for these histidine-related compounds as endogenous antioxidants in brain and muscle.


35.    Aruoma OI, Laughton MJ and Halliwell B (1989). Carnosine, homocarnosine and anserine: could they act as antioxidants in vivo? Biochem J. 264: 863-9. Department of Biochemistry, University of London King's College, U.K. Carnosine, homocarnosine and anserine have been proposed to act as antioxidants in vivo. Our studies show that all three compounds are good scavengers of the hydroxyl radical (.OH) but that none of them can react with superoxide radical, hydrogen peroxide or hypochlorous acid at biologically significant rates. None of them can bind iron ions in ways that interfere with 'site-specific' iron-dependent radical damage to the sugar deoxyribose, nor can they restrict the availability of Cu2+ to phenanthroline. Homocarnosine has no effect on iron ion-dependent lipid peroxidation; carnosine and anserine have weak inhibitory effects when used at high concentrations in some (but not all) assay systems. However, the ability of these compounds to interfere with a commonly used version of the thiobarbituric acid (TBA) test may have led to an overestimate of their ability to inhibit lipid peroxidation in some previous studies. By contrast, histidine stimulated iron ion-dependent lipid peroxidation. It is concluded that, because of the high concentrations present in vivo, carnosine and anserine could conceivably act as physiological antioxidants by scavenging .OH, but that they do not have a broad spectrum of antioxidant activity, and their ability to inhibit lipid peroxidation is not well established. It may be that they have a function other than antioxidant protection (e.g. buffering), but that they are safer to accumulate than histidine, which has a marked pro-oxidant action upon iron ion-dependent lipid peroxidation. The inability of homocarnosine to react with HOCl, interfere with the TBA test or affect lipid peroxidation systems in the same way as carnosine is surprising in view of the apparent structural similarity between these two molecules.


36.    Babizhayev MA, Seguin MC, Gueyne J, Evstigneeva RP, Ageyeva EA and Zheltukhina GA (1994). L-carnosine (beta-alanyl-L-histidine) and carcinine (beta-alanylhistamine) act as natural antioxidants with hydroxyl-radical-scavenging and lipid-peroxidase activities. Biochem J. 304 ( Pt 2): 509-16. Moscow Helmholtz Research Institute of Eye Diseases, Russia. Carnosine (beta-alanyl-L-histidine) and carcinine (beta-alanylhistamine) are natural imidazole-containing compounds found in the non-protein fraction of mammalian tissues. Carcinine was synthesized by an original procedure and characterized. Both carnosine and carcinine (10-25 mM) are capable of inhibiting the catalysis of linoleic acid and phosphatidylcholine liposomal peroxidation (LPO) by the O2(-.)-dependent iron-ascorbate and lipid-peroxyl-radical-generating linoleic acid 13-monohydroperoxide (LOOH)-activated haemoglobin systems, as measured by thiobarbituric-acid-reactive substance. Carcinine and carnosine are good scavengers of OH. radicals, as detected by iron-dependent radical damage to the sugar deoxyribose. This suggests that carnosine and carcinine are able to scavenge free radicals or donate hydrogen ions. The iodometric, conjugated diene and t.l.c. assessments of lipid hydroperoxides (13-monohydroperoxide linoleic acid and phosphatidylcholine hydroperoxide) showed their efficient reduction and deactivation by carnosine and carcinine (10-25 mM) in the liberated and bound-to-artificial-bilayer states. This suggests that the peroxidase activity exceeded that susceptible to direct reduction with glutathione peroxidase. Imidazole, solutions of beta-alanine, or their mixtures with peptide moieties did not show antioxidant potential. Free L-histidine and especially histamine stimulated iron (II) salt-dependent LPO. Due to the combination of weak metal chelating (abolished by EDTA), OH. and lipid peroxyl radicals scavenging, reducing activities to liberated fatty acid and phospholipid hydroperoxides, carnosine and carcinine appear to be physiological antioxidants able to efficiently protect the lipid phase of biological membranes and aqueous environments.


37.    Babizhayev MA and Costa EB (1994). Lipid peroxide and reactive oxygen species generating systems of the crystalline lens. Biochim Biophys Acta. 1225: 326-37. Moscow Helmholtz Research Institute of Eye Diseases, Russia. Lipid peroxidation (LPO) could be one of the mechanisms of cataractogenesis, initiated by enhanced production of oxygen free radicals in the eye fluids and tissues and impaired enzymatic and non-enzymatic defences of the lens. The increased concentrations of primary molecular LPO products (diene conjugates, lipid hydroperoxides) and end fluorescent LPO products were detected in the lipid moiety of the aqueous humor samples obtained from patients with cataract as compared to normal donors. Isolated human transparent and cataractous lenses and normal mouse and rabbit lenses were incubated with liposomes in organ culture in the presence and absence of LPO inhibitors, free radical scavengers and enzymes (catalase, superoxide dismutase (SOD)) in order to examine the potential of the lenses to induce LPO in the surrounding medium. LPO assayed spectrophotometrically were diene and triene conjugates, and malonaldehydes (MDA) were determined as thiobarbituric acid-reactive material. A chemiluminescence detection catalysed by peroxidase was used to measure H2O2 and O2-. was assayed spectrophotometrically using cytochrome C reduction. The level of lipid peroxides in liposomes was significantly (2.5-4.5-fold) higher after 3 h of incubation of the transparent lenses (or the lenses at the initial stage of cataract) than after the proper time of incubation of human mature cataractous lenses and virtually no oxidation of liposomes was detected in the absence of the lens. LPO in this system was decreased in the presence of free radical scavengers and enzymes that degrade H2O2 (EDTA, SOD, L-carnosine, chelated iron and catalase). The most effective agent was EDTA which chelates the free metal cations required to generate O2-. radicals that initiate the free radical process culminating in LPO. Lenses generated more H2O2 into the medium in the presence of exogenous ascorbate. Release of the oxidants, (O2-., H2O2, OH. and lipid hydroperoxides) by the intact lenses in the absence of respiratory inhibitors indicates that these metabolites are normal physiological products inversely related to the lens life-span potential (maturity of cataract) generated, probably, through the metal-ion catalysed redox-coupled pro-oxidant activation of the lens reductants (ascorbic acid, glutathione).


38.    Gorbunov NV and Erin AN (1991). [Mechanism of antioxidant action of carnosine]. Biull Eksp Biol Med. 111: 477-8. The comparative study of the antiradical activity of carnosine and vitamin C was carried out by the means of the evaluation of quenching of ESR signals of 2,2-diphenyl-1-picrylhydrazyl (DFPH) and semiquinone radical of alpha-tocopherol. It was shown that carnosine is not able to quench the ESR signals of the stable radical of DFPH and semiquinone radical of alpha-tocopherol. It permits to conclude that: a) carnosine does not interact directly with highly active free radicals; b) carnosine is unable to regenerate the radical of alpha-tocopherol to form the antiradical synergistic couple. The data obtained are consistent with the idea that there is a difference between on the antioxidant mechanism action of vitamin C and carnosine due to the difference in the antiradical activity of these compounds.


39.    Kohen R, Misgav R and Ginsburg I (1991). The SOD like activity of copper:carnosine, copper:anserine and copper:homocarnosine complexes. Free Radic Res Commun. 12-13 Pt 1: 179-85. Department of Pharmacy, Hebrew University of Jerusalem, Hadasaah Medical Center, Israel. Carnosine, anserine and homocarnosine are natural compounds which are present in high concentrations (2-20 mM) in skeletal muscles and brain of many vertebrates. We have demonstrated in a previous work that these compounds can act as antioxidants, a result of their ability to scavenge peroxyl radicals, singlet oxygen and hydroxyl radicals. Carnosine and its analogues have been shown to be efficient chelating agents for copper and other transition metals. Since human skeletal muscle contains one-third of the total copper in the body (20-47 mmol/kg) and the concentration of carnosine in this tissue is relatively high, the complex of carnosine:copper may be of biological importance. We have studied the ability of the copper:carnosine (and other carnosine derivatives) complexes to act as superoxide dismutase. The results indicate that the complex of copper:carnosine can dismute superoxide radicals released by neutrophils treated with PMA in an analogous mechanism to other amino acids and copper complexes. Copper:anserine failed to dismute superoxide radicals and copper:homocarnosine complex was efficient when the cells were treated with PMA or with histone-opsonized streptococci and cytochalasine B. The possible role of these compounds to act as physiological antioxidants that possess superoxide dismutase activity is discussed.


40.    Salim-Hanna M, Lissi E and Videla LA (1991). Free radical scavenging activity of carnosine. Free Radic Res Commun. 14: 263-70. Department of Chemistry, Faculty of Science, University of Santiago, Chile. The capacity of carnosine to decrease free radical-induced damage was evaluated using the oxidation of brain homogenates, the 2,2'-azobis-2-amidino propane-induced oxidation of erythrocyte ghost membranes, the radiation induced inactivation of horseradish peroxidase and the 2,2'-azobis-2-amidino propane-induced inactivation of lysozyme. Carnosine addition up to 17 mM did not produce any significant protection in either lipid peroxidation system, as assayed by the oxygen uptake rate. Carnosine addition reduces the intensity of the visible luminescence emitted, apparently due to a dark decomposition of the luminescent intermediates. Carnosine addition protects horseradish peroxidase and lysozyme from free radical mediated inactivation. The mean carnosine concentrations required to inhibit the inactivation rates by 50% were 0.13 mM and 0.6 mM for horseradish peroxidase and lysozyme, respectively.


41.    MacFarlane N, McMurray J, O'Dowd JJ, Dargie HJ and Miller DJ (1991). Synergism of histidyl dipeptides as antioxidants. J Mol Cell Cardiol. 23: 1205-7. Institute of Physiology, Glasgow University, UK. Histidyl dipeptides such as carnosine (beta-alanyl-L-histidine) and homocarnosine (gamma-amino-butyryl-L-histidine) are reported at millimolar concentrations in several mammalian tissues (O'Dowd et al., 1988; House et al., 1989), but their precise physiological function, or functions, is uncertain. These compounds are known to be potent buffers at physiological pH (Davey, 1960). They are also able to restore functional capacity to fatigued muscle preparations, stimulate some glycolytic enzymes and maintain coupling between mitochondrial oxidation and phosphorylation (Severin, 1964). Histidyl dipeptides may also have antioxidant activity, though this finding is controversial. For example, Aruoma et al. have argued that these compounds, individually, are unable to scavenge superoxide (O2-.), hydrogen peroxide (H2O2) or hypochlorous acid (HOCl) at rates which could offer antioxidant protection in vivo. Since there is a range of these histidyl dipeptides within mammalian tissue we have investigated possible synergism between them in respect of antioxidant activity. Our results show that combining histidine-containing compounds at near physiological concentrations results in synergistic antioxidant activity.


42.    Yoshikawa T, Naito Y, Tanigawa T, Yoneta T, Yasuda M, Ueda S, Oyamada H and Kondo M (1991). Effect of zinc-carnosine chelate compound (Z-103), a novel antioxidant, on acute gastric mucosal injury induced by ischemia-reperfusion in rats. Free Radic Res Commun. 14: 289-96. First Department of Medicine, Kyoto Prefectural University of Medicine, Japan. The protective effect of a novel synthetic zinc-carnosine chelate compound, zinc N-(3-aminopropionyl)-L-histidine (Z-103), on the gastric mucosal injury induced by ischemia-reperfusion was studied in rats. Ischemia and reperfusion injury was produced on the rat stomach by applying a small clamp to the celiac artery for 30 min and by removal of the clamp for 30 min. The decrease in the gastric mucosal blood flow was not influenced by the treatment with Z-103. The increase in total area of the erosions on the stomach after ischemia-reperfusion and the increase in lipid peroxides in the gastric mucosa were significantly inhibited by the oral administration of Z-103. In addition, Z-103 inhibited lipid peroxidation of rat brain homogenate and liver microsome in vitro. These results suggest that the protective effect of Z-103 against the aggravation of gastric mucosal injury induced by ischemia-reperfusion may be due to its inhibitory effect on lipid peroxidation.


43.    Yoshikawa T, Naito Y, Tanigawa T, Yoneta T and Kondo M (1991). The antioxidant properties of a novel zinc-carnosine chelate compound, N-(3-aminopropionyl)-L-histidinato zinc. Biochim Biophys Acta. 1115: 15-22. First Department of Medicine, Kyoto Prefectural University of Medicine, Japan. A zinc-carnosine chelate compound, Z-103, attenuates gastric mucosal injuries and inhibits the increase of lipid peroxide in the gastric mucosa induced by burn shock or ischemia-reperfusion. However, the exact mechanism of the antioxidative effect of Z-103 is not clear. The antioxidant properties of a novel anti-peptic ulcer agent Z-103 in vitro were compared with those of zinc ion and L-carnosine. Z-103 scavenged superoxide anion radicals. Z-103 and ZnSO4, but not L-carnosine, inhibited the superoxide generation from polymorphonuclear leukocytes stimulated by opsonized zymosan, and also inhibited the generation of hydroxyl radicals by the Fenton reaction. The increase of lipid peroxides produced by rat brain homogenates and liver microsomes was also inhibited by Z-103 and ZnSO4. These findings indicate that the strong anti-ulcer and antioxidative actions of Z-103 in vivo are due to a combination of these antioxidant actions in vitro.


44.    Guliaeva IV (1992). [Prospects for designing medicines based on carnosine (several new applications)]. Biokhimiia. 57: 1398-403. The perspectives in application of carnosine, its analogs (histidine-containing dipeptides), and their derivatives as components of medicinal drugs are reviewed. These applications are based on antioxidative properties of carnosine and its analogs, their chelating activity towards transient valency metals as well as on their specific neurotransmitter functions in the brain. Combination of carnosine with other antioxidants and the use of copper or zinc complexes with histidine-containing dipeptides are considered as perspective trends in the design of new drugs.


45.    Hartman Z and Hartman PE (1992). Copper and cobalt complexes of carnosine and anserine: production of active oxygen species and its enhancement by 2-mercaptoimidazoles. Chem Biol Interact. 84: 153-68. Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218. Phosphate buffer solutions of two dipeptides prevalent in striated muscle, L-carnosine (beta-alanyl-L-histidine) and L-anserine (beta-alanyl-L-1-methylhistidine), produce active oxygen species as measured by bleaching of N,N-dimethyl-4-nitrosoaniline (RNO). Activity is enhanced 5-14-fold in the presence of 2-mercaptoimidazoles such as ergothioneine, carbimazole (3-methyl-2-mercaptoimidazole-1-carboxylate), methimazole (2-mercapto-1-methylimidazole) and 2-mercaptoimidazole but only slightly by thiourea and dimethylthiourea. Activity is proportional to carnosine concentration and to mercaptoimidazole concentration at a fixed concentration of the second component. A variety of imidazoles closely related to carnosine and anserine are inactive, even after addition of transition metal ions. Activity is moderately increased above the pKa of the carnosine imidazole ring (pH 7.2, 7.5 and 8.0) versus below the pKa (pH 6.5 and 6.8). Activity is slightly increased by addition of copper or cobalt ions but not by addition of ferrous or ferric ions. Activity is decreased by Chelex 100 pretreatment of phosphate buffer and stimulated when copper or cobalt ions are added to the chelated buffer but there is no significant stimulation by ferric ions. Catalase eliminates most activity but superoxide dismutase has little effect. We propose that metal-carnosine and metal-anserine complexes produce superoxide and also serve as superoxide dismutases with resultant accumulation of hydrogen peroxide. An unidentified radical produced from hydrogen peroxide subsequently bleaches RNO. From the biological distributions of carnosine, anserine and ergothioneine, we infer that deleterious effects are probably minimal under normal physiological circumstances due to tissue and cellular compartmentalization and to sequestration of these compounds and transition metal ions.


46.    Decker EA, Ivanov V, Zhu BZ and Frei B (2001). Inhibition of low-density lipoprotein oxidation by carnosine histidine. J Agric Food Chem. 49: 511-6. Department of Food Science, Chenoweth Laboratory, University of Massachusetts, Amherst 01003, USA. Carnosine is a beta-alanylhistidine dipeptide found in skeletal muscle and nervous tissue that has been reported to possess antioxidant activity. Carnosine is a potential dietary antioxidant because it is absorbed into plasma intact. This research investigated the ability of carnosine to inhibit the oxidation of low-density lipoprotein (LDL) in comparison to its constituent amino acid, histidine. Carnosine (3 microM) inhibited Cu2+-promoted LDL (20 of protein/mL) oxidation at carnosine/copper ratios as low as 1:1, as determined by loss of tryptophan fluorescence and formation of conjugated dienes. Carnosine (6 microM) lost its ability to inhibit conjugated diene formation and tryptophan oxidation after 2 and 4 h of incubation, respectively, of LDL with 3 microM Cu2+. Compared to controls, histidine (3 microM) inhibited tryptophan oxidation and conjugated diene formation 36 and 58%, respectively, compared to 21 and 0% for carnosine (3 microM) after 3 h of oxidation. Histidine was more effective at inhibiting copper-promoted formation of carbonyls on bovine serum albumin than carnosine, but carnosine was more effective at inhibiting copper-induced ascorbic acid oxidation than histidine. Neither carnosine nor histidine was a strong inhibitor of 2,2'-azobis(2-amidinopropane) dihydrochloride-promoted oxidation of LDL, indicating that their main antioxidant mechanism is through copper chelation.


47.    Trombley PQ, Horning MS and Blakemore LJ (2000). Interactions between carnosine and zinc and copper: implications for neuromodulation and neuroprotection. Biochemistry (Mosc). 65: 807-16. Biomedical Research Facility, Department of Biological Science, Florida State University, Tallahassee, Florida 32306-4340, USA. This review examines interactions in the mammalian central nervous system (CNS) between carnosine and the endogenous transition metals zinc and copper. Although the relationship between these substances may be applicable to other brain regions, the focus is on the olfactory system where these substances may have special significance. Carnosine is not only highly concentrated in the olfactory system, but it is also contained in neurons (in contrast to glia cells in most of the brain) and has many features of a neurotransmitter. Whereas the function of carnosine in the CNS is not well understood, we review evidence that suggests that it may act as both a neuromodulator and a neuroprotective agent. Although zinc and/or copper are found in many neuronal pathways in the brain, the concentrations of zinc and copper in the olfactory bulb (the target of afferent input from sensory neurons in the nose) are among the highest in the CNS. Included in the multitude of physiological roles that zinc and copper play in the CNS is modulation of neuronal excitability. However, zinc and copper also have been implicated in a variety of neurologic conditions including Alzheimer's disease, Parkinson's disease, stroke, and seizures. Here we review the modulatory effects that carnosine can have on zinc and copper's abilities to influence neuronal excitability and to exert neurotoxic effects in the olfactory system. Other aspects of carnosine in the CNS are reviewed elsewhere in this issue.


48.    Trombley PQ, Horning MS and Blakemore LJ (1998). Carnosine modulates zinc and copper effects on amino acid receptors and synaptic transmission. Neuroreport. 9: 3503-7. Department of Biological Science, Florida State University, Tallahassee 32306-4340, USA. Carnosine is a dipeptide which is highly concentrated in mammalian olfactory sensory neurons along with zinc and/or copper, and glutamate. Although carnosine has been proposed as a neurotransmitter or neuromodulator, no specific function for carnosine has been identified. We used whole-cell current- and voltage-clamp recording to examine the direct effects and neuromodulatory actions of carnosine on rat olfactory bulb neurons in primary culture. Carnosine did not evoke a membrane current or affect currents evoked by glutamate, GABA or glycine. Copper and zinc inhibited NMDA and GABA receptor-mediated currents and inhibited synaptic transmission. Carnosine prevented the actions of copper and reduced the effects of zinc. These results suggest that carnosine may indirectly influence neuronal excitability by modulating the effects of zinc and copper.


49.    Severina IS and Busygina OG (1992). [The role of carnosine in the function of soluble of guanylate cyclase]. Biokhimiia. 57: 1330-6. The effect of carnosine on activation of human platelet soluble guanylate cyclase has been studied in 105,000 g supernatants and partially purified haem-deficient enzyme preparations. In the 105,000 g supernatant carnosine (1 mM) inhibited (by about 70%) the enzyme activation caused by sodium nitroprusside. In partially purified haem-deficient guanylate cyclase preparations the inhibition of enzyme activation by sodium nitroprusside was 86%; further addition of carnosine had no effect on the enzyme activity. The strength of the activating effect of protoporphyrin IX on partially purified haem-deficient guanylate cyclase did not differ from that for the 105,000 g supernatant; this stimulating effect did not change after carnosine addition. A conclusion is drawn that the inhibiting effect of carnosine on the ability of guanylate cyclase to be activated by sodium nitroprusside is due to the dipeptide interaction with the guanylate cyclase haem.


50.    Severina IS (1992). Soluble guanylate cyclase of platelets: function and regulation in normal and pathological states. Adv Enzyme Regul. 32: 35-56. Institute of Biological and Medical Chemistry, U.S.S.R. Academy of Medical Sciences, Moscow. Chromatography of 105,000 x g supernatants of human and rat platelets on DEAE-cellulose yielded identical elution profiles containing 2 protein fractions (peaks I and II). Only peak II was found to possess guanylate cyclase activity. In the spectrum of the 105,000 x g supernatant of human platelets the absorption maximum was specified at 410 nm (the Soret band) which disappeared from the spectrum of the active protein fraction (peak II) but was detected in the nonactive fraction (peak I). The enzyme preparation was obtained in the heme-deficient form. In the experiments with rat platelets, the Soret band was absent from the corresponding spectra and the enzyme was not activated by sodium nitroprusside; i.e., in soluble guanylate cyclase of rat platelets, unlike the generally accepted notion, the heme is not a prosthetic group of the enzyme. It was shown that carnosine (beta-alanyl-L-histidine), a water-soluble antioxidant, inhibits guanylate cyclase activation by sodium nitroprusside. This inhibitory effect is caused by the interaction of carnosine with the guanylate cyclase heme and can be used for evaluating the degree of saturation of the enzyme with the heme. ADP-induced aggregation of human platelets (donors) is accompanied by a fall in the basal guanylate cyclase activity (with Mg2+) and the enhancement of the enzyme stimulation with sodium nitroprusside, protoporphyrin IX, arachidonic acid and L-arginine with simultaneous cGMP elevation in platelets. A hypothetic scheme of the regulatory role of cGMP in platelet aggregation is proposed. In the experiments with the acute myocardial ischemia of rats, 15 min after the surgery a sharp fall in the platelet guanylate cyclase activity accompanied by a decrease in the enzyme activity in the ischemic zone of the left ventricle of heart took place. The results provided evidence of the high sensitivity of platelet guanylate cyclase to pathological changes occurring in the myocardium at the earliest stages of the development of pathology.


51.    Severina IS (1994). [Soluble platelet guanylate cyclase: significance of heme in regulating enzymatic activity and the role of the enzyme in platelet aggregation]. Biokhimiia. 59: 325-39. The lability of the bond between the protein molecule of human platelet guanylate cyclase and heme (the prosthetic group of the enzyme) has been established. It was shown that soluble rat platelet guanylate cyclase exists in these cells originally in a heme-deficient form. The data obtained suggest that in contrast with the generally accepted view, heme is not the prosthetic group of this enzyme. The water-soluble antioxidant carnosine (beta-alanyl-L-histidine) inhibits the guanylate cyclase activation by sodium nitroprusside. This inhibitory effect is caused by carnosine interaction with the guanylate cyclase heme and can be used for evaluating the degree of the heme deficiency of the enzyme. Analysis of the mechanism of guanylate cyclase activation by nitroso complexes of some transient metals (Fe, Co, Cr) differing in the degree of NO oxidation demonstrated that the essential requirement for the realization of the hypotensive effect of these compounds is the activation of guanylate cyclase solely via a heme-dependent mechanism. The ADP-induced aggregation of human platelets (donors) is accompanied by enhanced stimulation of guanylate cyclase by various activators with a simultaneous increase in the intraplatelet cGMP level. This stimulation occurs irrespective of the involvement of the guanylate cyclase heme in the mechanism of enzyme regulation. It is concluded that guanylate cyclase acts via a negative feedback mechanism to control over platelet aggregation and mediates a signal to deaggregation. A hypothetic scheme for the regulatory role of cGMP in platelet aggregation is proposed.


52.    Severina IS (1995). [Soluble forms of guanylate cyclases: mechanism of activation by nitrogen oxide and role in platelet aggregation]. Vestn Ross Akad Med Nauk. 41-6. The paper gives data on the role of heme in the functioning soluble forms of guanylate cyclase (of human platelets, rat heart and platelets), on the mechanism of nitrogen oxide-induced heme-dependent activation of enzymes, on the role of platelet guanylate cyclase in the regulation of human platelet aggregation/disaggregation and on the mechanism of antihypertensive and antiaggregatory action of enzyme activators. The instability of relationships of the protein molecule of human platelet guanylate cyclase and heme (regarded as a prosthetic group of the enzyme) results in heme loss during purification of the enzyme and preparation of a heme-deficient agent having a drastically reduced ability to sodium nitroprusside activation. Soluble rat platelet guanylate cyclase was found to be present in these cell originally in a heme-deficient form, it was not activated by sodium nitroprusside and, unlike the routine concepts, heme is not a moiety of this enzyme molecule. The water soluble antioxidant carnosine (beta-alanyl-L-histidine) inhibits sodium nitroprusside activation of guanylate cyclase by interacting with the heme of enzyme of the NO group of nitroprusside and may be useful to reveal the degree of htmt saturation of guanylate cyclase. The study of the mechanism of activation of guanylate cyclase by nitroso complexes of transition metals (Fe, Cr, Co) showed that their realization of antihypertensive effects required only heme-dependent activation of the enzyme. ADF-induced aggregation of human (donor) platelets is followed by stimulation of guanylate cyclase by various activators (despite heme involvement in the mechanism of activation) with concurrent elevations of platelet cGMP levels.(ABSTRACT TRUNCATED AT 250 WORDS)


53.    Snimoniia GV, Tatishvili NI, Shiliia D, Bakanidze NT and Khachidze MV (1992). [The effect of carnosine on the activity of Na,K,ATPase: prospective uses in clinical cardiology]. Biokhimiia. 57: 1343-7. The effects of carnosine on erythrocyte membrane Na,K-ATPase and isolated enzyme in vitro as well as on membrane Na,K-ATPase activity and lipid peroxidation (LPO) in chronic heart failure (CHF) and acute myocardial infarction (AMI) have been studied. CHF and AMI have been shown to be associated with significant inhibition of the erythrocyte membrane Na,K-ATPase activity and LPO activation. Marked activation of erythrocyte membrane Na,K-ATPase by carnosine in comparison with the isolated enzyme has been established. The ability of carnosine to induce Na,K-ATPase activation and prevent membrane depolarization indicates that the dipeptide may be a useful tool in the pathogenetic therapy of CFH and AMI.


54.    Kurella EG, Tyulina OV and Boldyrev AA (1999). Oxidative resistance of Na/K-ATPase. Cell Mol Neurobiol. 19: 133-40. Laboratory of Clinical Neurochemistry, Institute of Neurology, Russian Academy of Medical Sciences, Moscow, Russia. 1. Oxidative modification of Na/K-ATPase from brain and kidney has been studied. Brain enzyme has been found to be more sensitive than kidney enzyme to inhibition by both H2O2 and NaOCl. 2. The inhibition of Na/K-ATPase correlates well with the decrease in a number of SH groups, suggesting that the latter belong mainly to ATPase protein and are essential for the enzyme activity. We suggest that the differences in the number, location, and accessibility of SH groups in Na/K-ATPase isozymes predict their oxidative stability. 3. The hydrophilic natural antioxidant carnosine, the hydrophobic natural antioxidant alpha-tocopherol, and the synthetic antioxidant ionol as well as the ferrous ion chelating agent deferoxamine were found to protect Na/K-ATPase from oxidation by different concentrations of H2O2. The data suggest that these antioxidants are effective due to their ability to neutralize or to prevent formation of hydroxyl radicals.


55.    Prokopieva VD, Bohan NA, Johnson P, Abe H and Boldyrev AA (2000). Effects of carnosine and related compounds on the stability and morphology of erythrocytes from alcoholics. Alcohol Alcohol. 35: 44-8. Mental Health Research Institute, Medical Academy of Sciences of Russia, Tomsk, Russia. The effects of carnosine and related compounds on erythrocytes from alcoholics were studied. In their presence, erythrocytes showed an increased ability to resist haemolysis and showed a more normal morphology, with carnosine and N-acetyl-carnosine being the most effective compounds. These beneficial properties of the dipeptides do not appear to be directly related to their antioxidant or buffering properties.


56.    Boldyrev AA (1993). Does carnosine possess direct antioxidant activity? Int J Biochem. 25: 1101-7. Department of Biochemistry, Moscow State University, Russia. 1. A brief review of development of ideas of the antioxidant activity of carnosine and related compounds is presented. 2. An analysis of the behaviour of carnosine in different models of free radical chain reactions shows that carnosine is a potent hydrophilic antioxidant of a direct non-enzymatic action. 3. It is characteristic of the higher activity of interaction with active hydroxyl radical. 4. However the known biological effects of carnosine cannot be explained only by its anti-oxidant properties.


57.    Boldyrev AA, Dudina EI, Dupin AM, Chasovnikova LV, Formaziuk VE, Sergienko VI, Mal'tseva VV, Stvolinskii SL, Tiulina OV and Kurella EG (1993). [A comparison of the antioxidative activity of carnosine by using chemical and biological models]. Biull Eksp Biol Med. 115: 607-9. The difference in the efficiency of carnosine as an antioxidant was found to be explained both by the source of carnosine and the specificity of models used to achieve visualization. Commercial carnosine samples were contaminated with compound (s) absorbing at 255-332 nm. At the same time they possessed better antioxidant activity in the models with Fe2-induced peroxidation process. In the case of chemical models for generation of active forms of oxygen (several modifications of the Fenton reaction) or during burst of superoxide generation by leucocytes, the antioxidant effect of carnosine did not depend of the source of the compound under study.


58.    Boldyrev AA, Koldobski A, Kurella E, Maltseva V and Stvolinski S (1993). Natural histidine-containing dipeptide carnosine as a potent hydrophilic antioxidant with membrane stabilizing function. A biomedical aspect. Mol Chem Neuropathol. 19: 185-92. Department of Biochemistry, Moscow State University, Russia. A review on the distribution and biological effects of carnosine and a hypothesis for its biological mechanisms of action are presented. Carnosine and its structural and functional relative, anserine, were found in skeletal muscles at the beginning of the century. Their effects on muscle-working capacity, on the stability of membrane-bound enzymes, as well as their potent immunomodulating property, could not be explained by their pH-buffering capacity or formation of the secondary metabolites histidine and beta-alanine alone. This article suggests that the basis for the biological activities of carnosine and relative compounds is their potent antioxidant and membrane-protecting activity. The plausible chemical mechanism of this activity is discussed, and data regarding the usage of carnosine as a drug for treatment of immunodeficiency are summarized.


59.    Pavlov AR, Revina AA, Dupin AM, Boldyrev AA and Yaropolov AI (1993). The mechanism of interaction of carnosine with superoxide radicals in water solutions. Biochim Biophys Acta. 1157: 304-12. A.N. Bach Institute of Biochemistry, USSR Academy of Science, Moscow. The antiradical activity and the radiation stability of carnosine in water solutions was studied by the pulse radiolysis technique with spectrophotometric registration of absorbance. The transient spectra were recorded in the range 245-670 nm during 2 x 10(-6)-20 s after the pulse using a flow system for continuous change and saturation of the samples by different gases. Also, the spectra of the stable products of radiolysis were studied. The results obtained give evidence that carnosine in water solutions in the presence of oxygen behaves like a multifunctional antioxidant. Even at low concentrations, dipeptide forms a charge-transfer complex (Car ... O2-., lambda max = 265 nm) with the superoxide radical which changes the reactivity of O2-.. The absorbance band of the complex was shifted towards lower energy as compared to superoxide radical lambda max = 255 nm). The interaction of carnosine with OH-radicals proceeding at very high rate and resulting in the formation of a stable product suggested another type of dipeptide activity. The kinetic mechanism of the interaction of carnosine with products of radiolysis of water in aerobic conditions is discussed.


60.    Hipkiss AR, Preston JE, Himswoth DT, Worthington VC and Abbot NJ (1997). Protective effects of carnosine against malondialdehyde-induced toxicity towards cultured rat brain endothelial cells. Neurosci Lett. 238: 135-8. Molecular Biology and Biophysics Group, King's College London, Strand, UK. Malondialdehyde (MDA) is a deleterious end-product of lipid peroxidation. The naturally-occurring dipeptide carnosine (beta-alanyl-L-histidine) is found in brain and innervated tissues at concentrations up to 20 mM. Recent studies have shown that carnosine can protect proteins against cross-linking mediated by aldehyde-containing sugars and glycolytic intermediates. Here we have investigated whether carnosine is protective against malondialdehyde-induced protein damage and cellular toxicity. The results show that carnosine can (1) protect cultured rat brain endothelial cells against MDA-induced toxicity and (2) inhibit MDA-induced protein modification (formation of cross-links and carbonyl groups).


61.    Hipkiss AR, Preston JE, Himsworth DT, Worthington VC, Keown M, Michaelis J, Lawrence J, Mateen A, Allende L, Eagles PA and Abbott NJ (1998). Pluripotent protective effects of carnosine, a naturally occurring dipeptide. Ann N Y Acad Sci. 854: 37-53. Molecular Biology and Biophysics Group, King's College London, Strand, United Kingdom. Carnosine is a naturally occurring dipeptide (beta-alanyl-L-histidine) found in brain, innervated tissues, and the lens at concentrations up to 20 mM in humans. In 1994 it was shown that carnosine could delay senescence of cultured human fibroblasts. Evidence will be presented to suggest that carnosine, in addition to antioxidant and oxygen free-radical scavenging activities, also reacts with deleterious aldehydes to protect susceptible macromolecules. Our studies show that, in vitro, carnosine inhibits nonenzymic glycosylation and cross-linking of proteins induced by reactive aldehydes (aldose and ketose sugars, certain triose glycolytic intermediates and malondialdehyde (MDA), a lipid peroxidation product). Additionally we show that carnosine inhibits formation of MDA-induced protein-associated advanced glycosylation end products (AGEs) and formation of DNA-protein cross-links induced by acetaldehyde and formaldehyde. At the cellular level 20 mM carnosine protected cultured human fibroblasts and lymphocytes, CHO cells, and cultured rat brain endothelial cells against the toxic effects of formaldehyde, acetaldehyde and MDA, and AGEs formed by a lysine/deoxyribose mixture. Interestingly, carnosine protected cultured rat brain endothelial cells against amyloid peptide toxicity. We propose that carnosine (which is remarkably nontoxic) or related structures should be explored for possible intervention in pathologies that involve deleterious aldehydes, for example, secondary diabetic complications, inflammatory phenomena, alcoholic liver disease, and possibly Alzheimer's disease.


62.    Hipkiss AR and Chana H (1998). Carnosine protects proteins against methylglyoxal-mediated modifications. Biochem Biophys Res Commun. 248: 28-32. Molecular Biology and Biophysics Group, King's College London, United Kingdom. Methylglyoxal (MG) (pyruvaldehyde) is an endogenous metabolite which is present in increased concentrations in diabetics and implicated in formation of advanced glycosylation end-products (AGEs) and secondary diabetic complications. Carnosine (beta-alanyl-L-histidine) is normally present in long-lived tissues at concentrations up to 20 mM in humans. Previous studies showed that carnosine can protect proteins against aldehyde-containing cross-linking agents such as aldose and ketose hexose and triose sugars, and malon-dialdehyde, the lipid peroxidation product. Here we examine whether carnosine can protect protein exposed to MG. Our results show that carnosine readily reacts with MG thereby inhibiting MG-mediated protein modification as revealed electrophoretically. We also investigated whether carnosine could intervene when proteins were exposed to an MG-induced AGE (i.e. lysine incubated with MG). Our results show that carnosine can inhibit protein modification induced by a lysine-MG-AGE; this suggests a second intervention site for carnosine and emphasizes its potential as a possible non-toxic modulator of diabetic complications.


63.    Hipkiss AR (2000). Carnosine and protein carbonyl groups: a possible relationship. Biochemistry (Mosc). 65: 771-8. Division of Biomolecular Sciences, GKT School of Biomedical Sciences, King's College London, London SE1 1UL, UK. Carnosine has been shown to react with low-molecular-weight aldehydes and ketones and has been proposed as a naturally occurring anti-glycating agent. It is suggested here that carnosine can also react with ("carnosinylate") proteins bearing carbonyl groups, and evidence supporting this idea is presented. Accumulation of protein carbonyl groups is associated with cellular ageing resulting from the effects of reactive oxygen species, reducing sugars, and other reactive aldehydes and ketones. Carnosine has been shown to delay senescence and promote formation of a more juvenile phenotype in cultured human fibroblasts. It is speculated that carnosine may intracellularly suppress the deleterious effects of protein carbonyls by reacting with them to form protein-carbonyl-carnosine adducts, i.e., "carnosinylated" proteins. Various fates of the carnosinylated proteins are discussed including formation of inert lipofuscin and proteolysis via proteosome and RAGE activities. It is proposed that the anti-ageing and rejuvenating effects of carnosine are more readily explainable by its ability to react with protein carbonyls than its well-documented antioxidant activity.


64.    Hipkiss AR (2004). Is carnosine a naturally occurring suppressor of oxidative damage in olfactory neurones? Rejuvenation Res. 7: 253-5. Centre for Experimental Therapeutics, William Harvey Research Institute, Barts' and the London School of Medicine and Dentistry, London, United Kingdom. Ghanbari et al. recently showed that neurones from olfactory lobes of Alzheimer's patients exhibit oxidative stress and it is well known that olfactory dysfunction frequently accompanies neurodegeneration. The olfactory lobe is normally enriched in carnosine, a relatively non-toxic (and sometimes abundant) dipeptide which possesses functions (anti-oxidant, antiglycator, scavenger of zinc and copper ions, toxic aldehydes and protein carbonyls) that are likely to suppress oxidative stress. It is suggested that carnosine's therapeutic potential should be explored in olfactory tissue. Should the peptide prove beneficial, olfactory carnosine administration could provide a direct route to compromised tissue, avoiding serum carnosinases.


65.    Hyland P, Duggan O, Hipkiss A, Barnett C and Barnett Y (2000). The effects of carnosine on oxidative DNA damage levels and in vitro lifespan in human peripheral blood derived CD4+T cell clones. Mech Ageing Dev. 121: 203-15. Cancer and Ageing Research Group, University of Ulster, Northern Ireland BT52 1SA, Coleraine, UK. Carnosine (beta-alanyl-L-histidine), an abundant naturally-occurring dipeptide has been shown to exhibit anti-ageing properties towards cultured cells, possibly due in part to its antioxidant/free radical scavenging abilities. In this paper the results of an investigation on the effects of carnosine, at the physiological concentration of 20 mM, on oxidative DNA damage levels and in vitro lifespan in peripheral blood derived human CD4+ T cell clones are reported. Under the culture conditions used (20% O(2)) long term culture with carnosine resulted in a significant increase in the lifespan of a clone derived from a healthy young subject. No such extension was observed when a T cell clone from a healthy old SENIEUR donor was similarly cultured. Culture with carnosine from the midpoint of each clone's lifespan did not have any effect on longevity, independent of donor age. Oxidative DNA damage levels were measured in the clones at various points in their lifespans. Carnosine acted as a weak antioxidant, with levels of oxidative DNA damage being lower in T cells grown long term in the presence of carnosine. The possibility that carnosine might confer anti-ageing effects to T cells under physiological oxygen tensions would appear to be worthy of further investigation.


66.    Tabakman R, Jiang H, Levine RA, Kohen R and Lazarovici P (2004). Apoptotic characteristics of cell death and the neuroprotective effect of homocarnosine on pheochromocytoma PC12 cells exposed to ischemia. J Neurosci Res. 75: 499-507. Department of Pharmacology and Experimental Therapeutics, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel. We recently improved an in vitro ischemic model, using PC12 neuronal cultures exposed to oxygen-glucose deprivation (OGD) for 3 hr in a special device, followed by 18 hr of reoxygenation. The cell death induced in this ischemic model was evaluated by a series of markers: lactate dehydrogenase (LDH) release, caspase-3 activation, presence of cyclin D1, cytochrome c leakage from the mitochondria, BAX cellular redistribution, cleavage of poly (ADP-ribose) polymerase (PARP) to an 85-kDa apoptotic fragment, and DNA fragmentation. The OGD insult, in the absence of reoxygenation, caused a strong activation of the mitogen-activated protein kinase (MAPK) isoforms extracellular regulated kinase (ERK), c-Jun NH2-terminal kinase (JNK), and stress-activated protein kinase (SAPK), also known as p-38. The detection of apoptotic markers and activation of MAPKs during the ischemic insult strongly suggest that apoptosis plays an important role in the PC12 cell death. Homocarnosine, a neuroprotective histidine dipeptide, present in high concentrations in the brain, was found to provide neuroprotection, as expressed by a 40% reduction in LDH release and caspase-3 activity at 1 mM. Homocarnosine reduced OGD activation of ERK 1, ERK 2, JNK 1, and JNK 2 by 40%, 46%, 55%, and 30%, respectively. These results suggest that apoptosis is an important characteristic of OGD-induced neuronal death and that antioxidants, such as homocarnosine, may prevent OGD-induced neuronal death by inhibiting the apoptotic process and/or in relation to the differential attenuation of activity of MAPKs.


67.    Tabakman R, Lazarovici P and Kohen R (2002). Neuroprotective effects of carnosine and homocarnosine on pheochromocytoma PC12 cells exposed to ischemia. J Neurosci Res. 68: 463-9. Department of Pharmacology and Experimental Therapeutics, Hebrew University of Jerusalem, Jerusalem, Israel. The development of neuroprotective drugs against ischemic insults is hampered by the lack of pharmacological in vitro models. We developed an ischemic model using PC12 cell cultures exposed to oxygen-glucose-deprivation (OGD) followed by reoxygenation (18 hr) under regular atmospheric oxygen level. The toxicity induced in this model, that is partially caused by generation of reactive oxygen species (ROS), was measured morphologically as well as by the release of lactate dehydrogenase (LDH) and the prostaglandin PGE(2) from the cells. Carnosine and homocarnosine, histidine dipeptides antioxidants, found in high concentration in the brain, have been suggested to provide neuroprotection. Using the OGD model we found that 5 mM carnosine and 1 mM homocarnosine provided maximal neuroprotection of about 50% against OGD insult. This neuroprotective effect was similar to that of a known antioxidant, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (tempol), and was not observed in a serum-deprivation toxicity model of PC12 cells, indicating that carnosine and homocarnosine may act as antioxidant-neuroprotective agents in the brain. Our ischemic model may provide a useful tool for investigating the mechanisms involved in the neuroprotection afforded by histidine dipeptides.


68.    Dolgikh VT and Rusakov VV (1992). [The use of carnosine for reducing the post-resuscitation damage to the heart following acute fatal blood loss]. Anesteziol Reanimatol. 56-9. The experiments on random-bred male rats have established that 4 and 6 min clinical death of acute blood loss initiated lipid peroxidation processes (LPO), causing biomembrane damage, enhanced adenyl nucleotide catabolism, activated glycolysis and glycogenolysis in the heart muscle and caused cardiac arrhythmias. Carnosine at a dose 25 mg/kg administered together with pumped blood enhanced resuscitation efficacy and reduced considerably lethality in the early rehabilitation period. A favourable effect of carnosine is associated with its ability to restrict LPO processes, inhibit glycolysis and glycogenolysis and create optimal conditions for the functioning of membrane-located lipid-dependent enzymes.


69.    Dolgikh VT, Rusakov VV, Korpacheva OV and Sudakova AN (1992). Pathogenesis and pharmacorrection of early postresuscitation cardiac arrhythmia. Resuscitation. 23: 179-91. Division of Pathophysiology, Medical Institute, Omsk, Russia. Effect of acute lethal blood loss on character and frequency of cardiac arrhythmias in postresuscitation period has been studied. Experiments were carried out on mongrel male rats resuscitated after 4- and 6-min clinical death caused by acute blood loss. Electric cardiac instability was found in early postresuscitation period. Pacemaker migration, paroxysmal ventricular tachycardia, blockades and extrasystole that lead to ventricular fibrillation were observed in 20 percent of cases. Supported by correlative analysis it has been established that the main arrhythmogenic factors are abundance of catecholamines, free fatty acids, dienic conjugates, lactate and inhibition of Ca dependent ATPase. Antiarrhythmogenic effects of antihypoxant gutimin, the beta-adrenoreceptor blocker inderal, antioxidant oxypiridin-6 were noticed after their separate administration before clinical death. The same effect of carnosine and phosphocreatine administered during resuscitation also was noticed.


70.    Prokop'eva VD, Laptev BI and Afanas'ev SA (1992). [The protective effect of carnosine in hypoxia and reoxygenation of the isolated rat heart]. Biokhimiia. 57: 1389-92. The effect of carnosine (15 mM) on the contractile activity of isolated rat hearts contracting in an isotonic regime (37 degrees C at a 5 Hz stimulation frequency) has been studied. Carnosine added to the perfusing solution had no effect on the contractile activity either in hypoxia or during reoxygenation but decreased it with a simultaneous increase in the coronary flow during reoxygenation. Carnosine inhibited by 60% the lactate dehydrogenase release from cardiac cells. A conclusion is drawn that the protective effect of carnosine is due to its membrane-stabilizing action which is implemented during inhibition of peroxidation of membrane lipids.


71.    Rusakov VV and Dolgikh VT (1992). [Effects of carnosine on systemic hemodynamics and myocardial metabolism in rats in the early postresuscitation period]. Biull Eksp Biol Med. 113: 358-60. It was demonstrated in experiments on male rats that acute lethal blood loss and subsequent resuscitation after 4- and 6-min clinical death induce lipid peroxidation processes, decreased antioxidant enzyme activity, cause activation of anaerobic glycolysis in the myocardium. This metabolic heart impairment causes hemodynamic instability in postresuscitation period. 25 mg/kg of carnosine injected during resuscitation decreased functional-metabolic heart impairments and hemodynamic disarrangement as well as early postresuscitation lethality. The authors attribute positive carnosine effect to its significant antioxidant activity.


72.    Rusakov VV, Dolgikh VT and Korpacheva OV (1993). [The membrane-protective effect of carnosine in the post-resuscitation period after acute lethal blood loss]. Vopr Med Khim. 39: 26-8. Activation of serum enzymes in male rats was detected during the postresuscitation period after 4-6-min clinical death as a result of membrane destruction. Increase in the rate of lipid peroxidation and impairments of energy metabolism in the myocardium were responsible for destruction of cardiomyocyte biomembranes. Administration of carnosine (25 mg/kg body weight) simultaneously with compensation for blood loss obviated the membrane lipid bilayer destruction and contributed to the development of the optimal conditions for membrane-bound enzymes.


73.    Sdvigova AG, Panasenko OM, Luk'iashchenko VI, Sergienko VI and Lopukhin Iu M (1993). [Correction of lipoprotein lipid peroxidation in experimental atherosclerosis with polyunsaturated fatty acids combined with antioxidants]. Vopr Med Khim. 39: 30-3. Atherosclerotic lesion of the aorta and lipid peroxidation (LPO) in blood and in lipoproteins produced in hepatocytes were studied in rabbits with experimental atherosclerosis maintained on a diet enriched in polyunsaturated fatty acids containing in corn oil (2 ml/kg daily during 30 days) and antioxidants alpha-tocopherol and carnosine (2.5 mg/kg and 50 mg/kg, respectively, daily during 30 days). This diet exhibited a hypocholesterolemic effect accompanied by approximately a 10-fold decrease of the impaired aortic area, as well as lowered content of 2-thiobarbituric acid-positive LPO products occurring in blood and, especially, in apoB lipoproteins. The antioxidant-containing diet decreased distinctly the content of LPO products both in the liver tissue homogenate and lipoprotein fraction (d < 1.065 g/cm3) produced by hepatocytes during 30-min perfusion of liver tissue. The findings suggest that the diet enriched in polyunsaturated fatty acids and antioxidants contributed to a decrease of LPO products content in the blood serum and apoB lipoproteins as well as to the inhibition of lipoprotein oxidation during their synthesis in liver cells; the diet may be recommended for the prophylaxis and treatment of atherosclerosis.


74.    Julia P, Young HH, Buckberg GD, Kofsky ER and Bugyi HI (1991). Studies of myocardial protection in the immature heart. IV. Improved tolerance of immature myocardium to hypoxia and ischemia by intravenous metabolic support. J Thorac Cardiovasc Surg. 101: 23-32. University of California, Los Angeles School of Medicine, Department of Surgery. Thirteen immature puppies (2 to 4 kg) underwent 1 hour of acute hypoxia (oxygen tension 25 to 30 mm Hg), followed by 45 minutes of normothermic global ischemia on total vented bypass with normal blood reperfusion. Ventricular function was assessed by inscribing Starling function curves and measuring stroke work indices before hypoxia and after reperfusion. Seven puppies (control) received normal saline infusion at 4 ml/kg/hr. Six other puppies received a 4 ml/kg/hr intravenous infusion of glutamate/aspartate, glucose-insulin-potassium, mercaptopropionyl glycine, carnitine, and catalase during hypoxia and reperfusion. In control hearts, acute hypoxia depleted myocardial glutamate and aspartate by 52% (p less than 0.05 versus prehypoxia) and 48% (p less than 0.05 versus prehypoxia) and caused severe hemodynamic deterioration (55% decrease of stroke work index) (p less than 0.05 versus prehypoxia); three of seven (43%) required premature institution of bypass. Postischemic left ventricular function recovered to only 40% of control levels (p less than 0.05 versus prehypoxia). In contrast, intravenous metabolic infusions maintained tissue glutamate (p less than 0.05 versus control group) and aspartate (p less than 0.05 versus control group) in treated hearts during hypoxia and allowed cardiac index to rise 20% (p less than 0.05 versus prehypoxia); all treated hearts tolerated 1 hour of hypoxia, and stroke work recovered 70% (p less than 0.05 versus control group) of stroke work index after subsequent ischemia. Impaired tolerance of immature hearts to acute hypoxia and subsequent ischemia is due to substrate depletion. This impairment can be reduced by intravenous metabolic support during hypoxia and reperfusion and leads to improved recovery of postischemic function.


75.    Stvolinsky SL and Dobrota D (2000). Anti-ischemic activity of carnosine. Biochemistry (Mosc). 65: 849-55. Laboratory of Clinical Neurochemistry, Institute of Neurology, Russian Academy of Medical Sciences, Moscow, 123367 Russia. This review summarizes the data on anti-ischemic activity of carnosine. The pronounced anti-ischemic effects of carnosine in the brain and heart are due to the combination of antioxidant and membrane-protecting activity, proton buffering capacity, formation of complexes with transition metals, and regulation of macrophage function. In experimental cerebral ischemia, carnosine decreases mortality and is beneficial for neurological conditions of the animals. In cardiac ischemia, carnosine protects cardiomyocytes from damage and improves contractility of the heart. The data indicate that carnosine can be used as an anti-ischemic drug.


76.    Lee JW, Miyawaki H, Bobst EV, Hester JD, Ashraf M and Bobst AM (1999). Improved functional recovery of ischemic rat hearts due to singlet oxygen scavengers histidine and carnosine. J Mol Cell Cardiol. 31: 113-21. Department of Chemistry, University of Cincinnati, OH 45221, USA. There is increasing evidence that reactive oxygen species (ROS) contribute to post-ischemic reperfusion injury, but determination of the specific ROS involved has proven elusive. In the present study electron paramagnetic resonance (EPR) spectroscopy was used in vitro to measure the relative quenching of singlet oxygen (1O2) by histidine and carnosine (beta-alanyl-L-histidine) utilizing the hindered secondary amine 2,2,6,6-tetramethyl-4-piperidone HCl (4-oxo-TEMP). The relative effect of histidine and carnosine on functional recovery of isolated perfused rat hearts was also studied. Functional recovery was measured by left ventricular developed pressure (LVDP), first derivative of left ventricular pressure (dP/dt), heart rate (HR) and coronary flow (CF). EPR measurements and Stern-Volmer plots showed that 400 microM carnosine quenched 1O2 twice as effectively as equimolar histidine in vitro. Moreover, 10 mM histidine improved functional recovery of isolated rat hearts significantly more than 1 mM histidine. Furthermore, 1 mM carnosine improved functional recovery significantly more than equimolar histidine and as effectively as 10 mM histidine. Experiments with 1 mM mannitol, a known hydroxyl radical scavenger, did not show an improvement in functional recovery relative to control hearts, thereby decreasing the likelihood that hydroxyl radicals are the major damaging species. On the other hand, the correlation between improved functional recovery of isolated rat hearts with histidine and carnosine and their relative 1O2 quenching effectiveness in vitro provides indirect evidence for 1O2 as ROS participating in reperfusion injury.


77.    Yoshikawa T, Naito Y and Kondo M (1993). Antioxidant therapy in digestive diseases. J Nutr Sci Vitaminol (Tokyo). 39 Suppl: S35-41. First Department of Medicine, Kyoto Prefectural University of Medicine, Japan. This paper reviewed the recent advance in the antioxidant therapy for digestive diseases. Many reports have supported that lipid peroxidation mediated by oxygen radicals is implicated in the pathogenesis of gastric mucosal injury, intestinal damage, acute pancreatitis, and liver injury, and several kinds of antioxidant, which are divided into the preventive antioxidant and chain-breaking antioxidant, are effective in the treatment of these diseases. A new therapeutic approach using synthesized antioxidants, such as zinc-carnosine chelate compound and ebselen, has been also proposed in these fields.


78.    Naumova OV, Goncharenko EN and Deev LI (1992). [The effect of carnosine on the liver enzyme system in the irradiated body]. Biokhimiia. 57: 1373-7. The effect of carnosine on post-radioactive changes in lipid peroxidation (LPO) products in blood serum and cytochrome P-450 content in liver microsomes has been studied. Per os administration of carnosine 24 hours prior to irradiation in a minimal lethal dose (7 Gr) markedly decreases the post-radioactive accumulation of LPO products in rat blood serum one hour after irradiation and fully restores the post-radioactive decrease in the cytochrome P-450 content in rat liver microsomes on day 5 after irradiation. Besides, the ability of carnosine to prevent the post-radioactive decline in the activity of UDP-glucuronyl transferase. Another key enzyme of the liver detoxifying system, has been demonstrated. The data obtained testify to the ability of carnosine to provide effective protection against post-radioactive intensification of LPO in irradiated organisms.


79.    Chan WK, Decker EA, Chow CK and Boissonneault GA (1994). Effect of dietary carnosine on plasma and tissue antioxidant concentrations and on lipid oxidation in rat skeletal muscle. Lipids. 29: 461-6. Department of Animal Sciences, University of Massachusetts, Amherst 01003. The effect of dietary carnosine supplementation on plasma and tissue carnosine and alpha-tocopherol concentrations and on the formation of thiobarbituric acid reactive substances (TBARS) in rat skeletal muscle homogenates was evaluated. Plasma, heart, liver and hind leg muscle was obtained from rats fed basal semipurified diets or basal diets containing carnosine (0.0875%), alpha-tocopheryl acetate (50 ppm), or carnosine (0.0875%) plus alpha-tocopheryl acetate (50 ppm). Dietary carnosine supplementation did not increase carnosine concentrations in heart, liver and skeletal muscle. Dietary supplementation with both carnosine and alpha-tocopherol increased carnosine concentrations in liver 1.56, 1.51- and 1.51-fold as compared with diets lacking carnosine, alpha-tocopherol or both carnosine and alpha-tocopherol, respectively. Dietary supplementation with both carnosine and alpha-tocopherol also increased alpha-tocopherol concentrations in heart and liver 1-38-fold and 1.68-fold, respectively, as compared to supplementation with alpha-tocopherol alone. Dietary supplementation with carnosine, alpha-tocopherol or both carnosine and alpha-tocopherol was effective in decreasing the formation of TBARS in rat skeletal muscle homogenate, with dietary alpha-tocopherol and alpha-tocopherol plus carnosine being more effective than dietary carnosine alone. The data suggest that dietary supplementation with carnosine and alpha-tocopherol modulates some tissue carnosine and alpha-tocopherol concentrations and the formation of TBARS in rat skeletal muscle homogenates.


80.    Chan KM and Decker EA (1994). Endogenous skeletal muscle antioxidants. Crit Rev Food Sci Nutr. 34: 403-26. Chenoweth Laboratory, Department of Food Science, University of Massachusetts, Amherst, MA. Skeletal muscle is susceptible to oxidative deterioration due to a combination of lipid oxidation catalysts and membrane lipid systems that are high in unsaturated fatty acids. To prevent or delay oxidation reactions, several endogenous antioxidant systems are found in muscle tissue. These include alpha-tocopherol, histidine-containing dipeptides, and antioxidant enzymes such as glutathione peroxidase, superoxide dismutase, and catalase. The contribution of alpha-tocopherol to the oxidative stability of skeletal muscle is largely influenced by diet. Dietary supplementation of tocopherol has been shown to increase muscle alpha-tocopherol concentrations and inhibit both lipid oxidation and color deterioration. Dietary selenium supplementation has also been shown to increase the oxidative stability of muscle presumably by increasing the activity of glutathione peroxidase. The oxidative stability of skeletal muscle is also influenced by the histidine-containing dipeptides, carnosine and anserine. Whereas carnosine and anserine are affected by diet less than alpha-tocopherol and glutathione peroxidase, their concentrations vary widely with species and muscle type. In pigs, beef, and turkey muscle, carnosine concentrations are greater than anserine, while the opposite is true in rabbit, salmon, and chicken muscle. Anserine and carnosine are found in greater concentrations in muscle high in white fibers, with chicken white muscle containing over fivefold more anserine and carnosine than red muscle. Anserine and carnosine are thought to inhibit lipid oxidation by a combination of free radical scavenging and metal chelation.


81.    Quinn PJ, Boldyrev AA and Formazuyk VE (1992). Carnosine: its properties, functions and potential therapeutic applications. Mol Aspects Med. 13: 379-444. Biochemistry Department, King's College London, U.K. Carnosine and related dipeptides such as anserine are naturally-occurring histidine-containing compounds. They are found in several tissues most notably in muscle where they represent an appreciable fraction of the total water-soluble nitrogen-containing compounds. The biological role of these dipeptides are conjectural but they are believed to act as cytosolic buffering agents. Numerous studies have demonstrated, both at the tissue and organelle level, that they possess strong and specific antioxidant properties. Carnosine and related dipeptides have been shown to prevent peroxidation of model membrane systems leading to the suggestion that they represent water-soluble counterparts to lipid-soluble antioxidants such as alpha-tocopherol in protecting cell membranes from oxidative damage. Other roles ascribed to these dipeptides include actions as neurotransmitters, modulation of enzymic activities and chelation of heavy metals. Many claims have been made in respect of therapeutic actions of carnosine and histidine-containing dipeptides. These include antihypertensive effects, actions as immunomodulating agents, wound healing and antineoplastic effects. Many of these claims have not been convincingly documented nor subject to rigorous clinical evaluation. Nevertheless, there are examples where studies have shown considerable promise. One is the treatment of senile cataract in dogs and another is in acceleration of healing of surface wounds and burns to the skin. It is clear from this review that many of the effects of these histidine-containing dipeptides, especially in regard to claims for their therapeutic effects, need to be subjected to critical experimental and clinical examination. Several applications do, however, show clear evidence of being useful therapeutic agents.


82.    Reeve VE, Bosnic M and Rozinova E (1993). Carnosine (beta-alanylhistidine) protects from the suppression of contact hypersensitivity by ultraviolet B (280-320 nm) radiation or by cis urocanic acid. Immunology. 78: 99-104. Department of Veterinary Pathology, University of Sydney, Australia. Carnosine is a naturally occurring histidine-containing dipeptide in mammalian tissues for which a physiological role has not been defined. It has antioxidant properties, but has also been shown to be related metabolically to histidine and histamine, and to have immunopotentiating properties in vivo. It is shown here that carnosine presented topically or in the diet, potentiated the contact hypersensitivity reaction in hairless mice. Carnosine also prevented the systemic suppression of this reaction following exposure of the dorsal skin to ultraviolet B (UVB) radiation. Furthermore, carnosine prevented the systemic suppression caused by a topically applied lotion containing cis urocanic acid, indicating that it may act in competition with this UVB photoproduct which is believed to initiate many of the suppressive effects of UVB radiation.


83.    Hintz HF (1994). Nutrition and equine performance. J Nutr. 124: 2723S-2729S. Cornell University, Ithaca, NY 14853-4801. Some aspects of energy, protein and vitamin E nutrition of the performance horse are discussed. The amount, dietary source and time of ingestion of energy before exercise can influence performance. In 1989 the National Research Council (NRC) increased their estimates of energy required by racehorses. Recent studies indicate that the increase was reasonable. Many factors, however, can influence energy requirements. Therefore, the best measure would be body weight and composition of the horse. A proper balance of soluble carbohydrate, fiber, fat and protein is essential. Some guidelines are presented. The amount and type energy source given before exercise can influence level of plasma glucose and free fatty acids during exercise, but the effects of these changes in the concentration of metabolites remains to be determined. There is no evidence that increased dietary concentrations of protein are needed and, in fact, may impair performance. Supplemental histidine (to enhance carnosine levels) or carnitine appear to be of limited value for horses fed conventional diets. Dietary concentrations of vitamin E less than the 80 IU/kg recommended by NRC seem to adequately protect against exercise-induced peroxidation. The NRC value may be justified on the basis of immune response, but further studies are needed. Vitamin E has been shown to be involved with familial equine degenerative myeloencephalopathy and may be involved with equine motor neuron disease, a condition considered to be similar to amyotrophic lateral sclerosis in humans.


84.    Shohami E, Gati I, Beit-Yannai E, Trembovler V and Kohen R (1999). Closed head injury in the rat induces whole body oxidative stress: overall reducing antioxidant profile. J Neurotrauma. 16: 365-76. Department of Pharmacology, Hebrew University of Jerusalem, Israel. Traumatic injury to the brain triggers the accumulation of harmful mediators, including highly toxic reactive oxygen species (ROS). Endogenous defense mechanism against ROS is provided by low molecular weight antioxidants (LMWA), reflected in the reducing power of the tissue, which can be measured by cyclic voltammetry (CV). CV records biological peak potential (type of scavenger), and anodic current intensity (scavenger concentration). The effect of closed head injury (CHI) on the reducing power of various organs was studied. Water and lipid soluble extracts were prepared from the brain, heart, lung, kidney, intestine, skin, and liver of control and traumatized rats (1 and 24 h after injury) and total LMWA was determined. Ascorbic acid, uric acid, alpha-tocopherol, carotene and ubiquinol-10 were also identified by HPLC. The dynamic changes in LMWA levels indicate that the whole body responds to CHI. For example, transient reduction in LMWA (p<0.01) in the heart, kidney, lung and liver at 1 h suggests their consumption, probably due to interaction with locally produced ROS. However, in some tissues (e.g., skin) there was an increase (p<0.01), arguing for recruitment of higher than normal levels of LMWA to neutralize the ROS. alpha-Tocopherol levels in the brain, liver, lung, skin, and kidney were significantly reduced (p<0.01) even up to 24 h. We conclude that although the injury was delivered over the left cerebral hemisphere, the whole body appeared to be under oxidative stress, within 24 h after brain injury.


85.    Hirsch JD, Grillo M and Margolis FL (1978). Ligand binding studies in the mouse olfactory bulb: identification and characterization of a L-[3H]carnosine binding site. Brain Res. 158: 407-22. Binding sites for the dipeptide L-carnosine (beta-alanyl-L-histidine) have been detected in membranes prepared from mouse olfactory bulbs. The binding of L-[3H]-carnosine was saturable, reversible and stereospecific and had a Kd of about 770 nM. The stereospecific binding of L-carnosine represented about 30% of the total binding at pH 6.8, and decreased markedly with increasing pH. Binding was stimulated by calcium, unaffected by zinc, magnesium or manganese and inhibited by sodium and potassium. Carnosine binding was sensitive to trypsin and phospholipases A and C, but not to neuraminidase. Nystatin and filipin, which interact with membrane lipids, also interferred with binding. Some peptide analogues of carnosine were potent inhibitors of binding, but a variety of drugs serving as potent inhibitors in other binding systems had no effect on carnosine binding. Carnosine binding to mouse olfactory bulb membranes was 15-fold higher than that seen in membranes prepared from cerebral hemispheres, 5-fold higher than that seen in membranes prepared from cerebral hemispheres, 5-fold higher than in cerebellum membranes and 3-fold higher than in membranes from spinal medulla and the olfactory tubercle-lateral olfactory tract area. Binding sites for 6 other radiolabeled receptor ligands were also detected in bulb membranes. Peripheral deafferentation of the olfactory bulbs by intranasal irrigation with ZnSO4 led to a loss greater than 90% of the L-[3H]carnosine binding in 4--5 days with much smaller losses in binding of the other 6 ligands over a 180-day observation period. This initial loss of carnosine binding after denervation was due to a loss of binding site stereo-specificity followed by a loss of binding sites. The characteristics of the carnosine binding site in olfactory bulb fulfil 6 of the 7 criteria considered relevant for a functional receptor.


86.    De Marchis S, Modena C, Peretto P, Giffard C and Fasolo A (2000). Carnosine-like immunoreactivity in the central nervous system of rats during postnatal development. J Comp Neurol. 426: 378-90. Dipartimento di Biologia Animale e dell'Uomo, 10123 Torino, Italy. In the nervous system of adult rodents, the aminoacylhistidine dipeptides (carnosine and/or homocarnosine) have been shown to be expressed in three main populations of cells: the mature olfactory receptor neurons, a subset of glial cells, and the neuroblasts of the rostral migratory stream. The current study analyzed the distribution of these dipeptides during postnatal development within the rat brain and spinal cord focusing on their pattern of appearance in the glial cells. Double staining methods using antibodies against carnosine and some markers specific for immature (vimentin) and mature (glial fibrillary acidic protein and Rip) glial cell types were used. Glial immunostaining for the aminoacylhistidine dipeptides appears starting from postnatal day 6 and reaches the final distribution in 3-week-old animals. The occurrence of carnosine-like immunoreactivity in astrocytes lags behind that in oligodendrocytes suggesting that, as previously demonstrated by in vitro studies, oligodendrocytes are also able to synthesize carnosine and/or homocarnosine in vivo. Furthermore, the spatiotemporal patterns observed support the hypothesis that the production of these dipeptides coincides with the final stages of glia differentiation. In addition, a strong carnosine-like immunoreactivity is transiently seen in a small population of cells localized in the hypothalamus and in the subfornical organ from birth to postnatal day 21. In these cells, carnosine-like immunoreactivity was not colocalized with any of the glial specific markers used. Moreover, no evidence for colocalization of carnosine and gonadotropin-releasing hormone (GnRH) has been observed.


87.    Horning MS, Blakemore LJ and Trombley PQ (2000). Endogenous mechanisms of neuroprotection: role of zinc, copper, and carnosine. Brain Res. 852: 56-61. Biomedical Research Facility, Department of Biological Science, Florida State University, Tallahassee 32306-4340, USA. Zinc and copper are endogenous transition metals that can be synaptically released during neuronal activity. Synaptically released zinc and copper probably function to modulate neuronal excitability under normal conditions. However, zinc and copper also can be neurotoxic, and it has been proposed that they may contribute to the neuropathology associated with a variety of conditions, such as Alzheimer's disease, stroke, and seizures. Recently, we demonstrated that carnosine, a dipeptide expressed in glial cells throughout the brain as well as in neuronal pathways of the visual and olfactory systems, can modulate the effects of zinc and copper on neuronal excitability. This result led us to hypothesize that carnosine may modulate the neurotoxic effects of zinc and copper as well. Our results demonstrate that carnosine can rescue neurons from zinc- and copper-mediated neurotoxicity and suggest that one function of carnosine may be as an endogenous neuroprotective agent.


88.    Hoffmann AM, Bakardjiev A and Bauer K (1996). Carnosine-synthesis in cultures of rat glial cells is restricted to oligodendrocytes and carnosine uptake to astrocytes. Neurosci Lett. 215: 29-32. Max-Planck-Institut fur experimentelle Endokrinologie, Hannover, Germany. Cultures of glial cells consisting predominantly of oligodendrocytes and astrocytes were prepared to study whether the biosynthesis of carnosine (beta-Ala-His) and the cellular uptake of this dipeptide are processes which are associated with a specific cell type. Uptake of the radiolabeled precursor beta-alanine was observed in both cultures. Synthesis of radiolabeled carnosine, however, was only observed in oligodendrocyte cultures prepared from rat brain and spinal cord. During oligodendrocyte cultivation we observed a significant increase in the rate of carnosine synthesis which correlates with the differentiation of these cells as revealed by immunostaining with antibodies against oligodendrocyte markers. Carnosine synthesis was not observed in astroglia cell cultures that were depleted of residual O2-A progenitor cells and oligodendrocytes by antibody mediated complement cell killing. Contrary to the synthesis, carnosine was found to be taken up effectively only by astrocytes but not by oligodendrocytes.


89.    Baslow MH, Suckow RF, Berg MJ, Marks N, Saito M and Bhakoo KK (2001). Differential expression of carnosine, homocarnosine and N-acetyl-L-histidine hydrolytic activities in cultured rat macroglial cells. J Mol Neurosci. 17: 351-9. Nathan S. Kline Institute for Psychiatric Research, Center for Neurochemistry, Orangeburg, NY 10962, USA. N-acetyl-L-histidine (NAH) and N-acetyl-L-aspartate (NAA) are representatives of two series of substances that are synthesized by neurons and other cells in the vertebrate central nervous system (CNS). Histidine containing homologs of NAH are beta-alanyl-L-histidine or carnosine (Carn) and gamma-aminobutyrl-L-histidine or homocarnosine (Hcarn). A homolog of NAA is N-acetylaspartylglutamate (NAAG). These substances belong to a unique group of osmolytes in that they are synthesized in cells that may not to be able to hydrolyze them, and are released in a regulated fashion to a second compartment where they can be rapidly hydrolyzed. In this investigation, the catabolic activities for NAH, Carn, and Hcarn in cultured macroglial cells and neurons have been measured, and the second compartment for NAH and Hcarn has been identified only with astrocytes. In addition, oligodendrocytes can only hydrolyze Carn, although Carn can also be hydrolyzed by astrocytes. Thus, astrocytes express hydrolytic activity against all three substrates, but oligodendrocytes can only act on Carn. The cellular separation of these hydrolytic enzyme activities, and the possible nature of the enzymes involved are discussed.


90.    Bonfanti L, Peretto P, De Marchis S and Fasolo A (1999). Carnosine-related dipeptides in the mammalian brain. Prog Neurobiol. 59: 333-53. Dipartimento di Morfofisiologia Veterinaria, Universita degli Studi di Torino, Italy. Carnosine and structurally related dipeptides are a group of histidine-containing molecules widely distributed in vertebrate organisms and particularly abundant in muscle and nervous tissue. Although many theories have been proposed, the biological function(s) of these compounds in the nervous system remains enigmatic. The purpose of this article is to review the distribution of carnosine-related dipeptides in the mammalian brain, with particular reference to some cell populations wherein these molecules have been demonstrated to occur very recently. The high expression of carnosine in the mammalian olfactory receptor neurons led to infer that this dipeptide could play a role as a neurotransmitter/modulator in olfaction. This prediction, which has not yet been fully demonstrated, does not explain the localization of carnosine-related dipeptides in other cell types, such as glial and ependymal cells. A recent demonstration of high carnosine-like immunoreactivity in the subependymal layer of rodents, an area of the forebrain which shares with the olfactory neuroepithelium the occurrence of continuous neurogenesis during adulthood, supports the hypothesis that carnosine-related dipeptides could be implicated in some forms of structural plasticity. However, the particular distribution of these molecules in the subependymal layer, along with their expression in glial/ependymal cell populations, suggests that they are not directly linked to cell migration or cell renewal. In the absence of a unified theory about the role of carnosine-related dipeptides in the nervous system, some common features shared by different cell populations of the mammalian brain which contain these molecules are discussed.


91.    Bakardjiev A (1998). Carnosine and beta-alanine release is stimulated by glutamatergic receptors in cultured rat oligodendrocytes. Glia. 24: 346-51. Max-Planck-Institut fur experimentelle Endokrinologie, Hannover, Germany. Oligodendrocytes obtained from rat brain 0-2 A progenitor cells and differentiated in culture take up beta-alanine and synthesize carnosine (beta-Ala-His). The present study was designed to determine whether carnosine and beta-alanine are released from such cultures in response to some stimuli. An evoked release of these substances was not observed when the cells were incubated with 1 mM glutamate or 0.3 mM kainate. Addition of 0.1 mM cyclothiazide (CTZ) to the corresponding stimulus was accompanied by a distinct peak of release consisting of both carnosine and beta-alanine. The efflux was blocked completely in the case of kainate and to 80% in the case of glutamate when 50 microM 6,7-dinitroquinoxaline-2,3 (1H,4H)-dion (DNQX) was added to the cells at the same time as the receptor agonist. An increase of the efflux was observed in the presence of Zn2+. This effect was concentration-dependent. Total substitution of NaCl in the efflux medium by LiCl caused only a partial reduction of the release. GABA or 55 mM KCl showed only negligible effect. A large release of carnosine and beta-alanine was observed when oligodendrocyte cultures were treated with Ca2+ ionophore A 23187. These results suggest that oligodendrocytes exhibit a glutamate receptor-mediated release of carnosine and beta-alanine. The release is dependent on elevated intracellular Ca2+ concentration.


92.    Sunderman FW, Jr. (2001). Nasal toxicity, carcinogenicity, and olfactory uptake of metals. Ann Clin Lab Sci. 31: 3-24. Department of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont, USA. Occupational exposures to inhalation of certain metal dusts or aerosols can cause loss of olfactory acuity, atrophy of the nasal mucosa, mucosal ulcers, perforated nasal septum, or sinonasal cancer. Anosmia and hyposmia have been observed in workers exposed to Ni- or Cd-containing dusts in alkaline battery factories, nickel refineries, and cadmium industries. Ulcers of the nasal mucosa and perforated nasal septum have been reported in workers exposed to Cr(VI) in chromate production and chrome plating, or to As(III) in arsenic smelters. Atrophy of the olfactory epithelium has been observed in rodents following inhalation of NiSO4 or alphaNi3S2. Cancers of the nose and nasal sinuses have been reported in workers exposed to Ni compounds in nickel refining, cutlery factories, and alkaline battery manufacture, or to Cr(VI) in chromate production and chrome plating. In animals, several metals (eg, Al, Cd, Co, Hg, Mn, Ni, Zn) have been shown to pass via olfactory receptor neurons from the nasal lumen through the cribriform plate to the olfactory bulb. Some metals (eg, Mn, Ni, Zn) can cross synapses in the olfactory bulb and migrate via secondary olfactory neurons to distant nuclei of the brain. After nasal instillation of a metal-containing solution, transport of the metal via olfactory axons can occur rapidly, within hours or a few days (eg, Mn), or slowly over days or weeks (eg, Ni). The olfactory bulb tends to accumulate certain metals (eg, Al, Bi, Cu, Mn, Zn) with greater avidity than other regions of the brain. The molecular mechanisms responsible for metal translocation in olfactory neurons and deposition in the olfactory bulb are unclear, but complexation by metal-binding molecules such as carnosine (beta-alanyl-L-histidine) may be involved.


93.    Petroff OA, Hyder F, Mattson RH and Rothman DL (1999). Topiramate increases brain GABA, homocarnosine, and pyrrolidinone in patients with epilepsy. Neurology. 52: 473-8. Department of Neurology, Yale University, New Haven, CT 06520-8018, USA. OBJECTIVE: To measure the effects of topiramate on brain gamma-aminobutyric acid (GABA) in patients with epilepsy. BACKGROUND: Topiramate is a new antiepileptic medication with multiple putative mechanisms of action. In a recent meta-analysis of the newer antiepileptic drugs, topiramate was the most potent. Homocarnosine and pyrrolidinone are important metabolites of GABA with antiepileptic actions. METHODS: In vivo measurements of GABA, homocarnosine, and pyrrolidinone were made of a 14-cm3 volume in the occipital cortex using 1H spectroscopy with a 2.1-Tesla magnetic resonance spectrometer and an 8-cm surface coil. Twelve patients (eight women) with refractory complex partial seizures were studied while using topiramate. Nine epilepsy-free, drug-free volunteers served as control subjects. RESULTS: Topiramate increased mean brain GABA, homocarnosine, and pyrrolidinone concentrations in all patients. In paired measurements, brain GABA increased by 0.7 micromol/g (SD 0.3, n 7, 95% CI 0.4 to 1.0, p < 0.01). Homocarnosine increased by 0.5 micromol/g (SD 0.2, n 7, 95% CI 0.3 to 0.7, p < 0.001). Pyrrolidinone increased by 0.21 micromol/g (SD 0.06, n 7, 95% CI 0.16 to 0.27, p < 0.01). In two additional patients, GABA, homocarnosine, and pyrrolidinone increased after they were switched from vigabatrin to topiramate. CONCLUSIONS: Topiramate increased brain GABA, homocarnosine, and pyrrolidinone to levels that could contribute to its potent antiepileptic action in patients with complex partial seizures.


94.    Petroff OA, Hyder F, Rothman DL and Mattson RH (2000). Effects of gabapentin on brain GABA, homocarnosine, and pyrrolidinone in epilepsy patients. Epilepsia. 41: 675-80. Department of Neurology, Yale University, New Haven, Connecticut, USA. SUMMARY: PURPOSE: Gabapentin (GBP) was introduced as an antiepileptic drug (AED) and has been used in the management of neuropathic pain. We reported that daily dosing increased brain gamma-aminobutyric acid (GABA) in patients with epilepsy. This study was designed to determine how rapidly brain GABA and the GABA metabolites, homocarnosine and pyrrolidinone, increase in response to the first dose of GBP. METHODS: In vivo measurements of GABA, homocarnosine, and pyrrolidinone were made of a 14-cc volume in the occipital cortex by using a 1H spectroscopy with a 2.1-Tesla magnetic resonance spectrometer and an 8-cm surface coil. Six patients (four women) were studied serially after the first oral dose (1,200 mg) of GBP. Five patients (three women) taking a standard daily dose (range, 1,200-2,000 mg) of GBP were rechallenged with a single high dose (2,400 mg). RESULTS: The first dose of GBP increased median brain GABA by 1.3 mM (range, 0.4-1.8 mM) within 1 h. Homocarnosine and pyrrolidinone did not change significantly by 5 h. Daily GBP therapy increased GABA (0.5 mM; 95% CI, 0.2-0.9), homocarnosine (0.3 mM; 95% CI, 0.2-0.4), and pyrrolidinone (0.10 mM; 95% CI, 0.06-0.14). Rechallenging patients taking GBP daily increased median brain GABA by 0.4 mM (range, 0.3-0.5) within 1 h. CONCLUSIONS: GBP promptly elevates brain GABA and presumably offers partial protection against further seizures within hours of the first oral dose. Patients may expect to experience the anticonvulsant effects of increased homocarnosine and pyrrolidinone with daily therapy.


95.    Petroff OA, Mattson RH, Behar KL, Hyder F and Rothman DL (1998). Vigabatrin increases human brain homocarnosine and improves seizure control. Ann Neurol. 44: 948-52. Department of Neurology, Yale University, New Haven, CT 06520-8018, USA. Homocarnosine, a dipeptide of gamma-aminobutyric acid (GABA) and histidine, is thought to be an inhibitory neuromodulator synthesized in subclasses of GABAergic neurons. Homocarnosine is present in human brain in greater amounts (0.4-1.0 micromol/g) than in other animals. The antiepileptic drug vigabatrin increases human cerebrospinal fluid homocarnosine linearly with daily dose. By using 1H nuclear magnetic resonance spectroscopy, serial occipital lobe GABA and homocarnosine concentrations were measured in 11 patients started on vigabatrin. Daily low-dose (2 g) vigabatrin increased both homocarnosine and GABA. Larger doses of vigabatrin (4 g) further increased homocarnosine but changed GABA levels minimally. Seizure control improved with increasing homocarnosine and GABA concentrations. Patients whose seizure control improved with the addition of vigabatrin had higher mean homocarnosine, but the same mean GABA concentrations, than those whose seizure control did not improve. Increased homocarnosine may contribute to improved seizure control.


96.    Petroff OA, Hyder F, Collins T, Mattson RH and Rothman DL (1999). Acute effects of vigabatrin on brain GABA and homocarnosine in patients with complex partial seizures. Epilepsia. 40: 958-64. Department of Neurology, Yale University, New Haven, Connecticut 06520-8018, USA. PURPOSE: The acute, subacute, and chronic effects of vigabatrin (VGB) were studied in patients with refractory complex partial seizures. VGB increases human brain gamma-aminobutyric acid (GABA) and the related metabolites, homocarnosine and 2-pyrrolidinone. METHODS: In vivo measurements of GABA and homocarnosine were made of a 14-cc volume in the occipital cortex by using 1H spectroscopy with a 2.1-Tesla magnetic resonance spectrometer and an 8-cm surface coil. Six patients (three women) were studied serially during the initiation and maintenance of VGB as adjunct therapy. RESULTS: The first, 3 g dose of VGB increased brain GABA by 2.0 micromol/g within 81 min of oral administration. After 2 h, median edited GABA remained essentially the same for 2 days. The response to the second, 3-g dose of VGB given at 48 h was considerably less than that to the first dose, with a median increase of 0.5 micromol/g within 72 min. After 2-3 months, rechallenging patients taking 1.5-g VGB twice daily with 6 g increased GABA by 0.4 micromol/g within 87 min. Homocarnosine increased more gradually than GABA to above-normal levels after a week of VGB therapy. CONCLUSIONS: VGB promptly elevates brain GABA and presumably offers partial protection against further seizures within hours of the first oral dose. Once-a-day dosing is sufficient to increase GABA. Patients may be expected to experience the effects of increased homocarnosine within 1 week.


97.    Goddard AW, Mason GF, Almai A, Rothman DL, Behar KL, Petroff OA, Charney DS and Krystal JH (2001). Reductions in occipital cortex GABA levels in panic disorder detected with 1h-magnetic resonance spectroscopy. Arch Gen Psychiatry. 58: 556-61. Yale Anxiety Clinic, Yale Department of Psychiatry, 100 York St, Room 2J, New Haven, CT 06511, USA. BACKGROUND: There is preclinical evidence and indirect clinical evidence implicating gamma-aminobutyric acid (GABA) in the pathophysiology and treatment of human panic disorder. Specifically, deficits in GABA neuronal function have been associated with anxiogenesis, whereas enhancement of GABA function tends to be anxiolytic. Although reported peripheral GABA levels (eg, in cerebrospinal fluid and plasma) have been within reference limits in panic disorder, thus far there has been no direct assessment of brain GABA levels in this disorder. The purpose of the present work was to determine whether cortical GABA levels are abnormally low in patients with panic disorder. METHODS: Total occipital cortical GABA levels (GABA plus homocarnosine) were assessed in 14 unmedicated patients with panic disorder who did not have major depression and 14 retrospectively age- and sex-matched control subjects using spatially localized (1)H-magnetic resonance spectroscopy. All patients met DSM-IV criteria for a principal current diagnosis of panic disorder with or without agoraphobia. RESULTS: Patients with panic disorder had a 22% reduction in total occipital cortex GABA concentration (GABA plus homocarnosine) compared with controls. This finding was present in 12 of 14 patient-control pairs and was not solely accounted for by medication history. There were no significant correlations between occipital cortex GABA levels and measures of illness or state anxiety. CONCLUSIONS: Panic disorder is associated with reductions in total occipital cortex GABA levels. This abnormality might contribute to the pathophysiology of panic disorder.


98.    Pubill D, Verdaguer E, Sureda FX, Camins A, Pallas M, Camarasa J and Escubedo E (2002). Carnosine prevents methamphetamine-induced gliosis but not dopamine terminal loss in rats. Eur J Pharmacol. 448: 165-8. Unitat de Farmacological i Farmacognosia, Facultat de Farmacia, Universitat de Barcelona, Avgda. Diagonal 643, 08028 Barcelona, Spain. The neuroprotective effect of carnosine, an endogenous antioxidant, was examined against methamphetamine-induced neurotoxicity in rats. Carnosine pretreatment had no effect on dopamine terminal loss induced by methamphetamine (assessed by [3H]1-(2-[diphenylmethoxy]ethyl)-4-[3-phenylpropyl]piperazine([3H]GBR 12935) binding) but prevented microgliosis (increase in [3H]1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinolinecarboxami de ([3H]PK 11195) binding) in striatum. The 27-kDa heat-shock protein (HSP27) expression was used as indicator of astroglial stress. Methamphetamine treatment induced the expression of HSP27 in striatum and hippocampus, which was inhibited by carnosine, indicating a protective effect. Carnosine had no effect on methamphetamine-induced hyperthermia. Thus, carnosine prevents the microgliosis in striatum (where we did not detect loss of serotonergic terminals by [3H]paroxetine binding) and the expression of HSP27 in all the areas, but fails to prevent methamphetamine-induced loss of dopamine reuptake sites. Therefore, carnosine inhibits only some of the consequences of methamphetamine neurotoxicity, where reactive oxygen species play an important role.


99.    Gallant S, Kukley M, Stvolinsky S, Bulygina E and Boldyrev A (2000). Effect of carnosine on rats under experimental brain ischemia. Tohoku J Exp Med. 191: 85-99. Zoetic Neurosciences Ltd., England, UK. The effect of dietary carnosine on the behavioral and biochemical characteristics of rats under experimental ischemia was studied. Carnosine was shown to improve the animals orientation and learning in "Open Field" and "T-Maze" tests, and this effect was accompanied with an increase in glutamate binding to N-methyl-D-aspartate (NMDA) receptors in brain synaptosomes. Long-term brain ischemia induced by both sides' occlusion of common carotid arteries resulted in 55% mortality of experimental rats, and those who survived were characterized by partial suppression of orientation in T-maze. In the group of rats treated with carnosine, mortality after ischemic attack was decreased (from 55% to 17%) and most of the learning parameters were kept at the pre-ischemic level. Monoamine oxidase B (MAO B) activity in brain of the carnosine treated rats was not changed by ischemia significantly (compared to that of ischemic untreated rats) but NMDA binding to brain synaptosomal membranes being increased by ischemic attack was significantly suppressed and reached the level characteristic of normal brain. The suggestion was made that carnosine possesses a dual effect on NMDA receptors resulting in increase in their amount after long-term treatment but decrease the capacity to bind NMDA after ischemic attack.


©Wise Young PhD, MD

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