Stroke can occur when a brain blood vessel becomes blocked, preventing nearby tissue from getting essential nutrients. When brain tissue is deprived of oxygen and nutrients, it begins to die. Once this occurs, repair mechanisms, such as axonal sprouting, are activated as the brain attempts to overcome the damage. During axonal sprouting, healthy neurons send out new projections ("sprouts") that re-establish some of the connections lost or damaged during the stroke and form new ones, resulting in partial recovery. Before this study, it was unknown what triggered axonal sprouting. Previous studies suggested that GDF10 was involved in the early stages of axonal sprouting, but its exact role in the process was unclear. S. Thomas Carmichael, M.D., Ph.D., and his colleagues at the David Geffen School of Medicine at the University of California Los Angeles took a closer look at GDF10 to identify how it may contribute to axonal sprouting.

It has been widely believed that mechanisms of brain repair are similar to those that occur during development. Dr. Carmichael's team conducted comprehensive analyses to compare the effects of GDF10 on genes related to stroke repair with genes involved in development and learning and memory, processes that result in connections forming between neurons. Surprisingly, there was little similarity. The findings revealed that GDF10 affected entirely different genes following stroke than those involved in development or learning and memory. "We found that regeneration is a unique program in the brain that occurs after injury. It is not simply Development 2.0, using the same mechanisms that take place when the nervous system is forming," said Dr. Carmichael.

His group also found that GDF10 may be important for functional recovery after stroke. They treated mouse models of stroke with GDF10 and had the animals perform various motor tasks to test recovery. The results suggested that increasing levels of GDF10 were associated with significantly faster recovery after stroke. When the researchers blocked GDF10, the animals did not perform as well on the motor tasks, suggesting the repair mechanisms were impaired—and that the natural levels of GDF10 in the brain represent a signal for recovery.

Publishing their findings in Nature Neuroscience , scientists supported by the National Institute of Neurological Disorders and Stroke (NINDS) have discovered the molecule believed to be a major key to the brain's repair mechanism after it has suffered a stroke. The molecule is called growth and differentiation factor 10 (GDF10):The study included both animal and human models and tissue. They were able to watch the effects of GDF10 on axons. What they discovered was that numerous neurons grew and even more importantly, they may have debunked a long-held belief about the brain's recovery process post-injury.While much more research still lies ahead these scientists had some promising, early results using GDF10:

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