STANFORD, Calif. - The central nervous system, made up of the brain and spinal cord, never forgets a slight. Somehow, nerve cells lose the ability to regenerate: witness actor Christopher Reeve's paralysis after his horse threw him at a jump. To find a cure for such injuries, scientists must understand why nerve cells lose the ability to grow back. They know that these cells - called neurons - stop regenerating because a signal tells them to slow down during development. The problem is, scientists haven't known much about that signal.
Now, a team of Stanford University Medical Center researchers have identified the mechanism and some key cells involved in controlling regeneration. It turns out that the signal to slow down doesn't come from the neurons themselves, but from an outside source. The signal's effects appear to be permanent. The findings, published in the June 7 issue of Science, outline what may be a new avenue to explore in the search for brain-damage and paralysis treatments, the researchers say.
Messages move through the average neuron like tributaries flowing into a river. The tributaries are called dendrites, and they flow into the axon, the river itself, which in turn can share messages with dendrites further downstream.
When Reeve fell from his horse, neurons that weren't killed outright may have had their axons chopped in half, disconnecting them from the network. "This is the core problem in neural degenerative diseases, especially things like spinal cord injury. Axons that get cut don't grow past the site of the injury back to normal connections in the brain," said Jeffrey Goldberg, lead author of the paper and senior graduate student in the lab of Ben A. Barres, MD, PhD, associate professor of neurobiology and developmental biology. "When a person is paralyzed, that's permanent," he said.
Left to their own devices, neurons in the central nervous system grow back so slowly that they oPage: 1 2 3 Related biology news :1
Contact: Amy Adams
Stanford University Medical Center
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