Effects of MDMA exposure on the conditioned place preference produced by other drugs of abuse

Rationale: MDMA is a serotonergic neurotoxin but few pre-clinical studies have found long-term behavioural consequences. As human users of MDMA are polydrug users, it is important to investigate whether the behavioural effects of other drugs are modulated by prior exposure to MDMA. Objectives: This study investigated whether pretreatment with a multiple high dose regimen of MDMA altered the rewarding effects of other drugs of abuse. Methods: Adult male Lister Hooded rats (n=10/ group) were pretreated with 10 mg/kg MDMA or 1 ml/kg saline vehicle IP every 2 h for 6 h. Fourteen days later, conditioned place preference (CPP) to d-amphetamine (3 mg/kg), cocaine (20 mg/kg), ethanol (2.0 g/kg), heroin (0.5 mg/kg), or MDMA (10 mg/kg) was assessed. Results: In general, MDMA pretreatment had no effect on drug reward or habituation to the place conditioning apparatus. However, in contrast to saline pretreated rats, those animals receiving MDMA failed to show CPP after ethanol. Conclusion: MDMA pretreatment reduced the rewarding properties of ethanol. This finding may represent a functional consequence of MDMA-induced neurotoxicity. By extrapolation, human users of MDMA may be exposed to an increase in risks associated with alcohol abuse.