Antagonism of the neurotoxicity due to a single administration of methylenedioxymethamphetamine.

The role of transmitter release in the serotonergic neurotoxicity of methylenedioxymethamphetamine (MDMA) was examined using treatments altering MDMA-induced release or its consequences. The long-term decrease in 5-HT concentrations and tryptophan hydroxylase activity produced by MDMA was antagonized by depletion of vesicular monoamines with reserpine or interruption of monoamine synthesis with the decarboxylase inhibitor, monofluoromethyl DOPA (dihydroxyphenylalanine). Similar results were achieved by selectively inhibiting dopamine synthesis with alpha-methyl-p-tyrosine or through bilateral lesions of the substantia nigra with 6-hydroxydopamine. The dopamine receptor antagonist haloperidol was also effective in this regard. Although these results strongly implicate dopamine release in the long-term neurochemical effects of MDMA, protection was also provided by selective 5-HT2 antagonists indicating that the neurotoxicity is dependent upon the release of both dopamine and 5-HT.