For nerves to communicate with each other or another cell type, such as a muscle cell, they reach out with an arm or extension called an axon. Much like the telephone lines that line roadways, these arms require proper insulation, called myelin, composed mostly of lipids and some proteins.
Axons that transmit quick messages such as telling legs to walk need a lot of insulation. Sensory nerves such as those on the fingertips that prompt retraction from a hot stovetop need less.
"In any given nerve, some axons are wrapped heavily by myelin," Dr. Mei says. "It's based on nerve function. For example, if the nerve needs more speed in conducting a signal or information, like motor nerves, they would be wrapped more."
In fact, erbin is enriched in regions with a lot of myelinated axons, such as the sciatic nerve, which runs down the lower back into the legs, the researchers found.
Dr. Mei also is exploring the role of neuregulin 1 in cell talk in the brain. He and collaborators have identified a sort of a sort of check and balance for brain cell activity managed by neuregulin-1 in the area of the brain where complex reasoning and decisions about appropriate social behavior occur. They showed that neuregulin-1 and another receptor, ErbB4, help keep a healthy balance between excitation and inhibition of brain cells.
Their studies published in Neuron in 2007 showed neuregulin-1 and ErbB4, promote inhibition at the site of inhibitory synapses in the brain by increasing release of GABA, a major inhibitory neurotransmitter.
In 2000, the researchers showed the pair also are at excitatory synapses, communication points between neurons where the neurotransmitter glutamate excites cells to action. Here, neuregulin-1 and ErbB4 suppress excitation.
These findings have implications for conditions such as schizophrenia and seizures, where cell talk is out of control.
|Contact: Toni Baker|
Medical College of Georgia