MDMA in adolescent male rats: decreased serotonin in the amygdala and behavioral effects in the elevated plus-maze test.

Long-term behavioral consequences of the neurotoxicity produced by 3,4-methylenedioxymethamphetamine (MDMA) in the adolescent rat are still mostly unknown. Here, adolescent male rats (postnatal day 45 PND [45]) were exposed to 10 mg/kg of MDMA, intraperitoneally, every 2 h for 6 h. Controls were given 0.9% saline in the same protocol. Ten days after exposure, the behavioral effects of MDMA were assessed in the elevated plus-maze (n = 6 per group). After behavioral testing, animals were sacrificed and the amygdalae were dissected and processed for HPLC determination of dopamine (DA), serotonin (5-HT), and metabolites. Results showed a significant decrease in the 5-HT content (P < 0.05), but no significant alterations in DA or its metabolites. Behavioral observation in the elevated plus-maze showed a decreased number of entries in the unprotected arms (P < 0.05), which were correlated to the number of entries and time spent in the central platform. Rearing was also decreased (P < 0.05). No differences were observed in head dips, grooming, or number of entries in the protected arms of the apparatus. Therefore, we conclude that, as in the adult rat, exposure to MDMA in the adolescent rat is associated to long-term depletion of the 5-HT content and increased anxiety-like behavior.