Wise Young
10-02-2001, 12:27 AM
Journal of Neurochemistry, Vol. 76, No. 5, 2001 1395-1403
© 2001 International Society for Neurochemistry
Nicotine protects against arachidonic-acid-induced caspase activation, cytochrome c release and apoptosis of cultured spinal cord neurons
Rosario Garrido*, Mark P. Mattson, Bernhard Hennig and Michal Toborek*
* Department of Surgery, University of Kentucky Medical Center, Lexington, Kentucky, USA
Laboratory of Neurosciences, National Institute of Aging, Baltimore, Maryland, USA
Department of Animal Sciences, University of Kentucky, Lexington, Kentucky, USA
Address correspondence and reprint requests to Dr Michal Toborek, Department of Surgery, Division of Neurosurgery, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY 40536, USA. E-mail: mjtobo00@pop.uky.edu
Hydrolysis of membrane phospholipids of spinal cord neurons is one of the first events initiated in spinal cord trauma. In this process, free fatty acids, and in particular arachidonic acid, are released. Exposure of spinal cord neurons to free arachidonic acid can compromise cell survival and initiate apoptotic cell death. In order to determine potential mechanisms of apoptosis induced by arachidonic acid, activation of caspases -3, -8, and -9, as well as the release of cytochrome c into the cytoplasm were measured in cultured spinal cord neurons exposed to 10 µM of this fatty acid. In addition, because nicotine can exert a variety of neuroprotective effects, we hypothesized that it can prevent arachidonic acid induced apoptosis of spinal cord neurons. To study this hypothesis, spinal cord neurons were pretreated with nicotine (10 µM for 2 h) before arachidonic acid exposure and caspase activation as well as markers of apoptotic cell death were studied. Treatment of spinal cord neurons with arachidonic acid for up to 24 h significantly increased cytoplasmic levels of cytochrome c, induced caspase activation and induced DNA laddering, a hallmark of apoptotic cell death. Nicotine pretreatment markedly attenuated all these effects. In addition, antagonist studies suggest that the 7 nicotinic receptor is primarily responsible for these anti-apoptotic effects of nicotine. These results indicate that nicotine can exert potent neuroprotective effects by inhibiting arachidonic acid induced apoptotic cascades of spinal cord neurons.
Key Words: cell death - free fatty acids - neuroprotection - nicotine - spinal cord trauma
Abbreviations used: HNE, 4-hydroxynonenal; MAPK, mitogen-activated protein kinase; MEM, modified Eagle's medium; NF-B, necrosis factor kappa B; NO, nitric oxide; NOS, neuronal nitric oxide synthase; nNOS, neuronal nitric oxide synthase; PBS, phosphate-buffered saline
© 2001 International Society for Neurochemistry
Nicotine protects against arachidonic-acid-induced caspase activation, cytochrome c release and apoptosis of cultured spinal cord neurons
Rosario Garrido*, Mark P. Mattson, Bernhard Hennig and Michal Toborek*
* Department of Surgery, University of Kentucky Medical Center, Lexington, Kentucky, USA
Laboratory of Neurosciences, National Institute of Aging, Baltimore, Maryland, USA
Department of Animal Sciences, University of Kentucky, Lexington, Kentucky, USA
Address correspondence and reprint requests to Dr Michal Toborek, Department of Surgery, Division of Neurosurgery, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY 40536, USA. E-mail: mjtobo00@pop.uky.edu
Hydrolysis of membrane phospholipids of spinal cord neurons is one of the first events initiated in spinal cord trauma. In this process, free fatty acids, and in particular arachidonic acid, are released. Exposure of spinal cord neurons to free arachidonic acid can compromise cell survival and initiate apoptotic cell death. In order to determine potential mechanisms of apoptosis induced by arachidonic acid, activation of caspases -3, -8, and -9, as well as the release of cytochrome c into the cytoplasm were measured in cultured spinal cord neurons exposed to 10 µM of this fatty acid. In addition, because nicotine can exert a variety of neuroprotective effects, we hypothesized that it can prevent arachidonic acid induced apoptosis of spinal cord neurons. To study this hypothesis, spinal cord neurons were pretreated with nicotine (10 µM for 2 h) before arachidonic acid exposure and caspase activation as well as markers of apoptotic cell death were studied. Treatment of spinal cord neurons with arachidonic acid for up to 24 h significantly increased cytoplasmic levels of cytochrome c, induced caspase activation and induced DNA laddering, a hallmark of apoptotic cell death. Nicotine pretreatment markedly attenuated all these effects. In addition, antagonist studies suggest that the 7 nicotinic receptor is primarily responsible for these anti-apoptotic effects of nicotine. These results indicate that nicotine can exert potent neuroprotective effects by inhibiting arachidonic acid induced apoptotic cascades of spinal cord neurons.
Key Words: cell death - free fatty acids - neuroprotection - nicotine - spinal cord trauma
Abbreviations used: HNE, 4-hydroxynonenal; MAPK, mitogen-activated protein kinase; MEM, modified Eagle's medium; NF-B, necrosis factor kappa B; NO, nitric oxide; NOS, neuronal nitric oxide synthase; nNOS, neuronal nitric oxide synthase; PBS, phosphate-buffered saline