Age differences in (+)3,4-methylenedioxymethamphetamine (MDMA)-induced conditioned taste aversions and monoamine levels

Adolescence is a life stage characterized by developmental changes (both biological and behavioral) that may interact with the effects of drug administration. This was assessed in the present experiments in which adolescent and adult rats were compared in their ability to acquire taste aversions induced by (±)3,4-methylenedioxymethamphetamine (MDMA; 0, 1.0, 1.8 or 3.2 mg/kg) utilizing doses that are commonly self-administered by human users. Further, monoamine and metabolite levels in discrete brain regions were quantified using HPLC-ECD in order to determine if adolescent animals displayed a different neurochemical profile than do adult animals after being exposed to subcutaneous low doses of MDMA. Adolescent rats displayed less robust MDMA-induced taste aversions than adults during acquisition and on a final two-bottle aversion test. MDMA at these doses had no consistent effect on monoamine levels, and age was the predominant factor in predicting relative levels of monoamines and their metabolites (adolescent < adult). Given that drug abuse vulnerability is thought to be a function of the balance between the drug's rewarding and aversive effects, the relative insensitivity of adolescents to MDMA's aversive effects may be important to understanding abuse potential in this specific population.