Reinforcing Effects of MDMA (‘Ecstasy’) in Drug-Naive and Cocaine-Trained Rats

MDMA (ecstasy) is a common illegal drug among European adolescents who are typically inexperienced with hard drugs like cocaine. In rats, the reinforcing effect of intravenously self-administered MDMA did not differ between drug-naive animals and those previously trained with cocaine. MDMA sensitized rats to its own rate-increasing effect but not to that of cocaine. No carryover of cocaine's reinforcing effect to MDMA was observed, indicating that MDMA and cocaine produce distinct interoceptive stimuli in rats.

Study at a glance

Abstract

3,4-Methylenedioxymethamphetamine (MDMA; ‘ecstasy’) is one of the most prevalent illegal drugs of abuse among European adolescents, a population not generally experienced with respect to ‘hard’ drugs such as cocaine. We, therefore, determined the reinforcing effect of intravenously self-administered MDMA in a fixed ratio 1 time-out 150 s schedule of reinforcement in rats that were truly drug naive and compared it to cocaine-trained rats. The reinforcing effect of MDMA [0.032–10 mg/(kg·injection)] did not differ between drug-naive rats and cocaine-trained ones. MDMA sensitized the animals to its own rate-increasing effect but not to that of cocaine. When MDMA was tested after cocaine, there was no carryover of cocaine’s reinforcing effect to that of MDMA, suggesting that MDMA and cocaine produce distinct interoceptive stimuli in rats.