Heat increases 3,4-methylenedioxymethamphetamine self-administration and social effects in rats.

3,4-Methylenedioxymethamphetamine (MDMA, "Ecstasy") is a drug frequently used under hot conditions in nightclubs. In rats tested in the social interaction paradigm, greater prosocial effects of MDMA (5.0 mg/kg) were seen at a hot temperature (30 degrees C) relative to normal laboratory temperature (21 degrees C). In the intravenous drug self-administration paradigm, hot temperature (30 degrees C) increased the number of MDMA infusions (0.1, 0.3 or 1.0 mg/kg/infusion) self-administered by rats. Hot temperatures thus appear to affect both the social and reinforcing effects of MDMA.