nd nerve fibers, which may be why we have developed careful controls that tell cells to stop making new connections. The crowded central nervous system has ways to say ‘OK, we’re done’ to keep nerves from sprouting willy-nilly and making inappropriate connections. But in gaining the ability to crowd nerves close together, we have given up flexibility - the ability to heal after injury.”
“If you sever your finger, it can be surgically reattached, and nerve fibers typically grow back so that you can use your finger again,” says Schnaar. “In contrast, the injured brain and spinal cord are rocky terrain for nerve fiber growth,” he says. “Finding ways to smooth that road might help the nerve fibers to regrow.”
Several molecules in the spinal cord are known to stop nerve fibers from growing. Schnaar refers to these molecules as axon regeneration inhibitors, or simply ARIs.
“Treatments that eliminate ARIs might allow the nerve ends to regain their natural regenerative abilities as they do in the periphery and improve recovery,” says Schnaar.
The researchers looked at the boundary between the spinal cord and the periphery to see if they could coax a nerve end to grow out of the inhibitory spinal cord into a more permissive environment that contains fewer ARIs. They chose to mimic the injury commonly seen in motorcycle accidents, called brachial plexus avulsion, because it involves nerves at the boundary between the spinal cord and periphery.
The researchers surgically severed nerves that normally extend from the spinal cord to the shoulder of anesthetized rats. They then transplanted a nerve from the hind leg of the same animal into the spinal cord to reconnect the injured nerve ends.
To coax the injured nerve ends to grow fibers and connect to the transplanted nerve, they used an implanted pump to bathe the area with one of three different enzymes known to destroy ARIs. Four weeks after transplantatiPage: 1 2 3 4 Related medicine news :1
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