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

In rats, MDMA (ecstasy) causes hyperthermia at normal or warm room temperatures but hypothermia in cool conditions. At 15°C, MDMA rapidly lowered rectal temperature; this effect was blocked by a dopamine D2 receptor antagonist but not a D1 antagonist. A neurotoxic MDMA regimen reduced serotonin in the brain by about 30% after a week. This serotonin lesion did not affect tail temperature increases when rats moved from 20°C to 30°C, but led to lower tail temperatures when returned to 24°C. Acute MDMA in lesioned rats at 30°C caused a sustained drop in tail temperature. The findings suggest that thermoregulatory problems in MDMA-lesioned rats stem partly from impaired heat loss through the tail, a key heat-loss organ.

Study at a glance

Abstract

3,4‐Methylenedioxymethamphetamine (MDMA, ‘ecstasy’) administration to rats produces hyperthermia if they are housed in normal or warm ambient room temperature ( T a ) conditions (20°C), but hypothermia when in cool conditions ( T a 17°C). We have now investigated some of the mechanisms involved. MDMA (5 mg kg −1 i.p.) produced a rapid decrease in rectal temperature in rats at T a 15°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.). MDMA (5 mg kg −1 ) did not alter the tail temperature of rats at T a 15°C, but decreased the tail temperature of rats at T a 30°C. 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°C to 30°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°C. 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°C compared to nonlesioned controls. These data suggest that the thermoregulatory problems previously observed in MDMA‐lesioned rats housed at T a 30°C result, partially, from their inability to lose heat by vasodilation of the tail, a major heat‐loss organ in this species. British Journal of Pharmacology (2005) 146 , 306–312. doi: 10.1038/sj.bjp.0706318