| RESEARCH |
Jonathan V. Sweedler, professor of chemistry at the University of Illinois, Urbana-Champaign, is trying to identify previously unknown catabolites of neurotransmitters. "You want a fairly information-rich analytical technique," Sweedler told C&EN. "We're using a very selective detector, using a UV excitation wavelength that only looks for certain types of compounds and is effective for things like indolamines and catecholamines, which happen to be neurotransmitters of interest." His group uses capillary electrophoresis coupled with laser-induced fluorescence (CE-LIF) detection to study the serotonin content in identified neurons in the marine snails Aplysia californica and Pleurobranchaea californica. Sweedler likes to use these simple marine invertebrates because they have a relatively small number--approximately 10,000--of neurons, which are physiologically well defined. In one example, Sweedler and his collaborators used CE-LIF to study the difference between feeding and quiescence in Pleurobranchaea. Serotonin levels track the feeding threshold, Sweedler said. The snails were paired according to size and starved for about a month. Then one of the slugs in each pair was fed. The hungry animals had a fourfold higher serotonin level in one particular neuron, the metacerebral cell. Sweedler and his coworkers have also been able to identify new catabolites in the sea snails. They found that sometimes nitric oxide causes the formation of serotonin dimers. So far, Sweedler doesn't know how often this dimer forms or what its function is. Sweedler also identified serotonin sulfate catabolites with unknown function. He speculates they may play a role in regulating global serotonin levels in the brain. |
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