Acute and subchronic effects of methylenedioxymethamphetamine [(+/-)MDMA] on locomotion and serotonin syndrome behavior in the rat.

Specific behaviors comprising the serotonin syndrome (low body posture, forepaw treading, headweaving) and the autonomic signs of piloerection and salivation were determined and analyzed with locomotor activity in response to MDMA at three doses (2.5, 5.0, and 7.5 mg/kg). All behaviors were dose-responsive. Serotonin syndrome behaviors increased in both intensity and duration of response with increasing doses. In contrast, locomotion varied only in intensity. Subchronic injections, in the same group of animals, permitted an analysis of acute vs. subchronic effects on these same behaviors. Both the serotonin syndrome and locomotor behaviors were augmented on subsequent testing, indicating that, (+/-)MDMA, like amphetamine, is capable of producing behavioral sensitization.