In a study published in the June 3rd issue of the journal Nature, a team led by UCSD professor of biology Nicholas Spitzer shows that manipulating the electrical activity of developing nerve cells can alter the type of neurotransmitter--chemicals that carry information between nerve cells at junctions called "synapses"--they produce. A review paper discussing these results will appear in July in Trends in Neurosciences. The results are important because scientists had long believed that the different kinds of neurotransmitters used by different nerve cells were genetically programmed into the cell.
"If you were to ask neuroscientists what learning is in cellular and molecular terms, none would have said it is the changing identity of neurotransmitters," says Spitzer. "That would have been heresy because everyone thought neurotransmitter identity was genetically programmed. Our results show that by altering neural activity, you can change the identity of the neurotransmitter a particular cell produces, raising the possibility that disorders caused by problems with neurotransmitters could be treated by modifying neural activity."
In the study, the UCSD group increased or decreased the electrical activity in frog embryonic spinal nerve cells by altering the current through nerve cell membranes with drugs or by genetic manipulation. They found that increases in activity increased the levels of neurotransmitters that inhibit the activity of nerve cells across the synapse and decreased the levels of neurotransmitters that stimulate nerve cells. Decreasing electrical activity had the opposite effect.