Inosine Promotes Nerve Growth

BOSTON, Apr. 19, 2011 /NewsRelease/ - By combining two molecular therapies-each known to promote some recovery on its own-the researchers achieved more nerve growth along with a greater recovery of motor function than with either treatment alone. One therapy, inosine, is really a naturally-present molecule that promotes nerve growth; the other is NEP1-40, an agent that counteracts natural inhibitors of nerve growth.

After the acute treatment window closes, the only real effective treatment for stroke is physical/occupational therapy. Now scientists from Children’s Hospital Boston report a two-pronged molecular therapy leading to significant recovery of skilled motor function inside a rat model of stroke. Their findings are reported April 20 in the Journal of Neuroscience.

“When you put these two together, you get much stronger growth of new circuits than either one alone, and very striking functional improvements,” says senior author Larry Benowitz, Ph.D., of the Children’s Department of Neurosurgery.

Strokes in humans often damage the motor cortex somewhere of the brain, interfering with skilled motor functions about the opposite side from the body. Led by Laila Zai, Ph.D., a postdoctoral fellow in Benowitz’s lab and also the study’s first author, the researchers modeled this scenario by inducing strokes somewhere of the rats’ brains-specifically in a part of the motor cortex that controls forelimb movement. They then examined the rats’ ability to perform a skilled reaching task-retrieving food-with the forelimb on the opposite side.

After Three or four weeks, rats given both inosine and NEP1-40 could perform the task-which required coordinated movements from the paw and digits-with success equivalent to those before the stroke. Benowitz likens the complexity of the task to a person eating with utensils or operating a joystick.

Benowitz has three issued U.S. patents and several U.S. and foreign patent applications pending for that use of inosine to treat stroke, spinal cord injury and traumatic brain injury, along with a pending patent application for the inosine/NEP1-40 combined treatment of CNS injury. Earlier studies from his lab, including one published in 2002 and the other published last year, indicated that inosine encourages nerve fibers to grow from the uninjured side of the brain into parts of the spinal cord that have lost nerve fibers because of stroke. This compensatory rewiring of neural circuits was matched by functional improvements. A separate 2007 study from the University of Cambridge also discovered that inosine promotes recovery of skilled motor function following traumatic brain injury in rats.