The molecular mechanism of "ecstasy" [3,4-methylenedioxy-methamphetamine (MDMA)]: serotonin transporters are targets for MDMA-induced serotonin release.

MDMA (ecstasy) acts on serotonin transporters in both the plasma membrane and secretory vesicles. In plasma membrane vesicles from human platelets, MDMA inhibits serotonin transport and imipramine binding by directly interacting with the sodium-dependent serotonin transporter, and it stimulates serotonin efflux in a stereo-specific, sodium-dependent, and imipramine-sensitive manner via transporter-mediated exchange. In vesicles from bovine adrenal chromaffin granules containing the vesicular biogenic amine transporter, MDMA inhibits ATP-dependent serotonin accumulation and stimulates efflux by dissipating the transmembrane pH difference and directly interacting with the vesicular transporter.

Study at a glance

Abstract

MDMA ("ecstasy") has been widely reported as a drug of abuse and as a neurotoxin. This report describes the mechanism of MDMA action at serotonin transporters from plasma membranes and secretory vesicles. MDMA stimulates serotonin efflux from both types of membrane vesicle. In plasma membrane vesicles isolated from human platelets, MDMA inhibits serotonin transport and [3H]imipramine binding by direct interaction with the Na(+)-dependent serotonin transporter. MDMA stimulates radiolabel efflux from plasma membrane vesicles preloaded with [3H]serotonin in a stereo-specific, Na(+)-dependent, and imipramine-sensitive manner characteristic of transporter-mediated exchange. In membrane vesicles isolated from bovine adrenal chromaffin granules, which contain the vesicular biogenic amine transporter, MDMA inhibits ATP-dependent [3H]serotonin accumulation and stimulates efflux of previously accumulated [3H]serotonin. Stimulation of vesicular [3H]serotonin efflux is due to dissipation of the transmembrane pH difference generated by ATP hydrolysis and to direct interaction with the vesicular amine transporter.