3,4-methylenedioxymethamphetamine (MDMA)-induced release of endogenous serotonin from the rat dorsal raphe nucleus in vitro: Effects of fluoxetine and tryptophan.

The serotonin releasing action of 3,4-methylenedioxymethamphetamine on slices of dorsal raphe nucleus from rat was investigated. The slices were maintained in a gas-liquid interface perfusion chamber used for electrophysiological recording. Microdialysis probes designed for use on the slice surface were employed to measure the release of endogenous serotonin which was determined using liquid chromatography with electrochemical detection. Three minute duration exposure of the slices to 100 micromolar 3,4-methylenedioxymethamphetamine caused a long lasting release of endogenous serotonin. Fluoxetine, a serotonin transport inhibitor, reduced the amount of serotonin release. Tryptophan added to the perfusion solution increased both the duration and amount of serotonin released. These results further support earlier work on the mechanism of 3,4-methylenedioxymethamphetamine induced inhibition of serotonin neuronal firing.