Studies on the effect of MDMA ('ecstasy') on the body temperature of rats housed at different ambient room temperatures

1 3,4-Methylenedioxymethamphetamine ( MDMA, 'ecstasy') administration to rats produces hyperthermia if they are housed in normal or warm ambient room temperature ( Ta) conditions ( >= 20 degrees C), but hypothermia when in cool conditions (T-a <= 17 degrees C). We have now investigated some of the mechanisms involved. 2 MDMA ( 5 mg kg(-1) i. p.) produced a rapid decrease in rectal temperature in rats at Ta 15 degrees C. This response was blocked by pretreatment with the dopamine D-2 receptor antagonist remoxipride ( 10 mg kg (-1) i. p.), but unaltered by pretreatment with the D-1 antagonist SCH23390 ( 1.1 mg kg(-1) i. p.). 3 MDMA ( 5 mg kg(-1)) did not alter the tail temperature of rats at T-a 15 degrees C, but decreased the tail temperature of rats at T-a 30 degrees C. 4 A neurotoxic dose of MDMA ( three doses of 5 mg kg(-1) given 3 h apart) decreased cortical and hippocampal 5-HT content by approximately 30% 7 days later. This lesion did not influence the rise in tail temperature when rats were moved from T-a 20 degrees C to 30 degrees C compared to nonlesioned controls, but did result in a lower tail temperature than that of controls when they were returned to T-a 24 degrees C. 5 Acute administration of MDMA ( 5 mg kg(-1)) to MDMA-lesioned rats produced a sustained decrease in tail temperature in rats housed at T-a 30 degrees C compared to nonlesioned controls. 6 These data suggest that the thermoregulatory problems previously observed in MDMA-lesioned rats housed at T-a 30 degrees C result, partially, from their inability to lose heat by vasodilation of the tail, a major heat-loss organ in this species.