Effects of ritanserin on the 3,4-methylenedioxymethamphetamine-induced decrease in striatal serotonin concentration and on the increase in striatal neurotensin and dynorphin A concentrations.

The concentration of serotonin (5-HT) measured in rat striatum was reduced to 75% of control 1 week after a single subcutaneous administration of dl-3,4-methylenedioxymethamphetamine (MDMA, 20 mg/kg). This decrease was prevented by pretreating the animals with ritanserin. Eighteen hours after MDMA (20 mg/kg), striatal concentrations of neurotensin-like immunoreactivity (NTLI) and of dynorphin A-like immunoreactivity (DLI) were increased to 250 and 487% of control, respectively, but ritanserin failed to prevent these changes. This study supports a role for 5-HT2 receptors in the mechanism by which a single high dose of MDMA induces neuronal damage to the serotonergic system, but not the MDMA-induced increase in central NTLI and DLI concentrations.