Exercise can stimulate injured neurons to regenerate their axons, which are the primary transmission lines of the nervous system, according to a study published June 1 in the print edition of the Proceedings of the National Academy of Sciences, and the last week of May in the early online edition.
"Our experiments show that the nervous system responds to injury in the same way that it responds to activity that creates or eliminates connections needed for brain cells to communicate with one another," said Jeffery L. Twiss, head of Nemours neuroscience research lab and corresponding author of the study, titled "Voluntary Exercise Increases Axonal Regeneration From Sensory Neurons."
"In time, our further understanding of the mechanisms behind this process could aid research into new treatments for brain diseases that affect the lives of millions of Americans," Twiss said.
Neuronal activity enhances synaptic plasticity, with new connections forming between frequently used neural pathways. The term "synaptic plasticity" refers to the ability to maintain or improve synapse function. Twiss' team and a group of researchers from UCLA, under the leadership of Fernando Gómez-Pinilla, found that this plasticity can affect the ability of nerves to regenerate.
Previous research from the UCLA laboratory of Gómez-Pinilla, professor of neurosurgery and physiological science, has shown that following exercise, neurotrophin levels increase in the brain and spinal cord. Neurotrophins, growth factors that promote neuron survival, positively regulate synaptic plasticity underlying high-order neural processes such as learning and memory, and walking. This research clearly demonstrates that managed physical activity can be a realistic therapy to promote functional recovery after brain and spinal cord injury.
To investigate how exercise-induced changes in neurotrophins affect synaptic plasticity, Twiss and Gómez-Pinilla's groups examined the growth of sensory neurons from rats that had access to running wheels for zero, three or seven days.