Elevation of ambient room temperature has differential effects on MDMA-induced 5-HT and dopamine release in striatum and nucleus accumbens of rats

Abstract

3,4-Methylenedioxymethamphetamine (MDMA) produces acute dopamine and 5-HT release in rat brain and a hyperthermic response, which is dependent on the ambient room temperature in which the animal is housed. We examined the effect of ambient room temperature (20 and 30°C) on MDMA-induced dopamine and 5-HT efflux in the striatum and shell of nucleus accumbens (NAc) of freely moving rats by using microdialysis. Locomotor activity and rectal temperature were also evaluated. In the NAc, MDMA (2.5 or 5 mg/kg, i.p.) produced a substantial increase in extracellular dopamine, which was more marked at 30°C. 5-HT release was also increased by MDMA given at 30°C. In contrast, MDMA-induced extracellular dopamine and 5-HT increases in the striatum were unaffected by ambient temperature. At 20°C room temperature, MDMA did not modify the rectal temperature but at 30°C it produced a rapid and sustained hyperthermia. MDMA at 20°C room temperature produced a two-fold increase in activity compared with saline-treated controls. The MDMA-induced increase in locomotor activity was more marked at 30°C due to a decrease in the activity of the saline-treated controls at this high ambient temperature. These results show that high ambient temperature enhances MDMA-induced locomotor activity and monoamine release in the shell of NAc, a region involved in the incentive motivational properties of drugs of abuse, and suggest that the rewarding effects of MDMA may be more pronounced at high ambient temperature. © 2005 Nature Publishing Group All rights reserved.