Attenuation of the disruptive effects of (+/-)3,4-methylenedioxymethamphetamine and cocaine on delayed matching-to-sample performance with D1 versus D2 antagonists.

Evidence suggests that acute exposure to (+/-)3,4-methylenedioxymethamphetamine (MDMA) produces qualitatively similar effects on recognition task performance as other stimulant-type drugs. The current study examined whether there was a similar neurochemical basis to these memory effects by examining the effects of a D1 receptor antagonist (SCH23390) and D2 antagonist (eticlopride) on MDMA- or cocaine-induced impairments in delayed matching-to-sample performance in rats. At low doses it was shown that eticlopride was ineffective in antagonizing either MDMA or cocaine's effects, and at higher doses exacerbated their effects. In contrast, the D1 receptor antagonist SCH23390 was only able to significantly attenuate the disruption caused by MDMA, but not cocaine's effects. Therefore, although present evidence suggests that the effect of acute MDMA on memory-task performance may be related to its effects at D1 receptor sites, there may be differences between MDMA and cocaine in the precise neurochemical pathways involved despite their having similar cognitive effects.