Quantitative Analysis by Reverse Phase High Performance Liquid Chromatography of 5-Hydroxytryptamine in the Central Nervous System of the Red Swamp Crayfish, Procambarus clarkii.

The concentrations of 5-hydroxytryptamine (5-HT) in central nervous organs of the red swamp crayfish, Procambarus clarkii, were determined by reverse phase high performance liquid chromatography (RPHPLC) with electrochemical detection. The quantity ranged between 54 and 168 pg/mg wet weight of tissue. The amount is highest in the brain, followed in decreasing order by the thoracic ganglia, subesophageal ganglion, eyestalks, and abdominal nerve cord. Significant increases in the levels of 5-HT in the eyestalks, brain, subesophageal ganglion, and thoracic ganglia occurred in crayfish exposed for three days to continuous light on a white background, whereas the 5-HT levels in these tissues decreased in crayfish kept in darkness. Electrical stimulation of central nervous organs in vitro produced significant decreases in the levels of 5-HT. Fenfluramine (5-HT releaser), 5,6-DHT (5-HT neurotoxin), and reserpine (5-HT depletor) induced significant decreases in the 5-HT levels in the portions of the central nervous system tested.