Behavioral profile of 3,4-methylenedioxy-methamphetamine (MDMA) in agonistic encounters between male mice.

1. The effects of acute administration of 3, 4-methylenedioxymethamphetamine (MDMA), a synthetic amphetamine derivative (0.5-20 mg/kg, i.p.) on agonistic behavior elicited by isolation in male mice were examined. 2. Individually housed mice were exposed to anosmic "standard opponents" 30 min after MDMA injection, and the encounters were videotaped and evaluated using an ethologically based analysis. 3. MDMA (5-20 mg/kg) exhibited a behavioral profile characterized by a reduction of aggression (threat and attack) without a concomitant increase of immobility, accompanied by a decrease of social investigation and a increment of exploration from a distance, avoidance/flee and defense/submission behaviors. 4. This ethopharmacological profile might suggest an anxiogenic-like activity of MDMA in albino male mice.