MDMA (Ecstasy) substitutes for the ethanol discriminative cue in HAD but not LAD rats

Selectively bred high- and low-alcohol-drinking (HAD/LAD) rats were trained to discriminate the interoceptive stimuli produced by IP-administered 600 mg/kg ethanol (10% w/v in a two-lever, food-motivated operant task. Once criterion discrimination was attained, animals were tested with 3.0, 1.5, 1.0, and 0.5 mg/kg MDMA. Although no differences in alcohol discrimination were observed between the HAD and LAD animals, the HAD line was significantly more sensitive than the LAD line to the effects of MDMA. These results provide additional information to the growing body of evidence suggesting serotonergic mediation of some of the behavioral effects of ethanol.