Our results indicate specific binding sites for MDMA exist in the rat brain. Studies performed in our laboratory have indicated that ( + )-MDMA is a potent releaser of serotonin in vitro (Schmidt and Lovenberg, unpublished observations) while in vivo,a single dose of MDMA reduces striatal serotonin levels for up to 7 days after a single dose (Schmidt et al., unpublished observations). This latter effect is indicative of serotonergic neurotoxicity and can be blocked by coadministration of citalopram, a serotonergic reuptake inhibitor. Interestingly, citalopram did not antagonize the binding of [3H](+-)-MDMA in the current study and in vitro uptake studies performed using striatal synaptosomes indicate that [3H](+-)-MDMA is probably not concentrated in nerve terminals (data not shown). The results suggest MDMA may possess a number of pharmacological activities in the mammalian CNS.
