Conditioning following repeated exposure to MDMA in rats: Role in the maintenance of MDMA self-administration.

Abstract

There has been some controversy in the literature concerning the ability of +/-3,4 methylenedioxymethamphetamine (MDMA) to reinforce operant responding in rats. In the present study, operant responding maintained by intravenous MDMA infusions increased when the fixed ratio schedule was increased from 1 to 5, decreased when saline was substituted for MDMA, and increased again when MDMA was reintroduced. During self-administration training, each infusion of MDMA was paired with the illumination of a light stimulus. The role of the continued presentation of this drug-associated stimulus in operant responding was measured in groups of rats that had received comparable exposure (average 19 daily test sessions) to MDMA during training. When either the light stimulus or the drug infusion was omitted, operant responding decreased gradually over the 15-day test period following training. When both the light stimulus and the MDMA infusion were omitted, there was a dramatic decrease in operant responding that persisted for the entire 15-day test period. These findings suggest that cues associated with MDMA develop conditioned properties that might contribute to drug taking.

Differential changes in mesolimbic dopamine following contingent and non-contingent MDMA self-administration in mice

“…Hence, a decline in its reinforcing properties has been observed in monkeys self-administering the drug for 18 months (Fantegrossi et al 2004). However, in rats self-administering high doses of MDMA (0.25-1.0 mg/kg per infusion), no reduction in reinforcing effects was apparent (Schenk et al 2003;Daniela et al 2004Daniela et al , 2006. Thus, there are still no clear data as to whether self-administered MDMA produces changes in reward-related behavior.…”

MDMA Self-Administration in Laboratory Animals: A Summary of the Literature and Proposal for Future Research

“…If so, this would explain the apparent resistance to extinction that we had informally observed. This was formally tested [67] by first providing substantial self-administration experience to a group of rats. The influence of the continued presentation of a light stimulus that had been associated with self-administered MDMA infusions on lever pressing behavior was measured.…”

Interactions between 3,4-Methylenedioxymethamphetamine and Ethanol in Humans and Rodents

“…There is also evidence that the interoceptive stimuli produced by MDMA in rats are different from those of other psychostimulants, at least from cocaine [33] . There is some proof that MDMA self-administration can be tied to environmental cues such as a light signal or increased ambient temperature [30,[34][35][36] . Cornish et al [34] showed, in the rat, that a relatively warm temperature (30 ° C) increased MDMA self-administration as compared to a lower temperature (21 ° C).…”

“…Cornish et al [34] showed, in the rat, that a relatively warm temperature (30 ° C) increased MDMA self-administration as compared to a lower temperature (21 ° C). In the approach reported by Daniela et al [35] , self-administration training was based on pairing an infusion with a light stimulus. Omitting the light stimulus in the selfadministering rats resulted in a gradual decrease in operant responding.…”