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Small changes in ambient temperature cause large changes in 3,4-methylenedioxymethamphetamine (MDMA)-induced
1University of Chicago, Department of Pharmacological and Physiological Sciences, Chicago, Illinois 60637, USA.
Abstract:
The amphetamine derivative 3,4-methylenedioxymethamphetamine (MDMA) is a drug of abuse and has been shown to be neurotoxic to 5-HT terminals in many species. MDMA-engendered neurotoxicity has been shown to be affected by both ambient temperature and core body temperature. We now report that small (2 degreesC) changes in ambient temperature produce changes in core temperature in MDMA-treated rats, but the same changes in ambient temperature do not affect core temperature of saline-treated animals. Furthermore, increases in core temperature of MDMA-treated animals increase neurotoxicity. Rats were given MDMA (20 or 40 mg/kg) or saline and placed in an ambient temperature of 20, 22, 24, 26, 28, or 30 degreesC using a novel temperature measurement apparatus that controls ambient temperature +/-0.5 degrees C. Two weeks after MDMA treatment, the rats were killed, and regional 5-HT and 5-hydroxyindole acetic acid levels were analyzed as a measure of neurotoxicity. Rats treated with MDMA at 20 and 22 degrees C showed a hypothermic core temperature response. Treatment with MDMA at 28 and 30 degreesC produced a hyperthermic response. At ambient temperatures of 20-24 degrees C, neurotoxicity was not observed in the frontal cortex, somatosensory cortex, hippocampus, or striatum. At ambient temperatures of 26-30 degrees C, neurotoxicity was seen and correlated with core temperature in all regions examined. These data indicate that ambient temperature has a significant affect on MDMA neurotoxicity, core temperature, and thermoregulation in rats. This finding has implications on both the temperature dependence of the mechanism of MDMA neurotoxicity and human use because fatal hyperthermia is associated with MDMA use in humans.
Insights
Ambient temperature significantly impacts 3,4-methylenedioxymethamphetamine (MDMA) neurotoxicity in rats. Higher temperatures increase MDMA
Area of Science:
- Neuroscience
- Pharmacology
- Toxicology
Background:
- 3,4-methylenedioxymethamphetamine (MDMA) is a drug of abuse known to cause neurotoxicity to serotonin (5-HT) terminals.
- Previous research indicates that ambient and core body temperature influence MDMA-induced neurotoxicity.
Purpose of the Study:
- To investigate the effect of ambient temperature on MDMA neurotoxicity and thermoregulation in rats.
- To determine the relationship between core body temperature changes and MDMA neurotoxicity across different ambient temperatures.
Main Methods:
- Rats were administered MDMA (20 or 40 mg/kg) or saline and exposed to controlled ambient temperatures (20-30°C).
- Core body temperature was monitored, and neurotoxicity was assessed by measuring 5-HT and 5-hydroxyindole acetic acid levels in brain regions two weeks post-treatment.
Main Results:
- MDMA treatment at lower ambient temperatures (20-22°C) induced hypothermia, while higher temperatures (28-30°C) caused hyperthermia.
- Neurotoxicity was not observed at ambient temperatures of 20-24°C.
- At ambient temperatures of 26-30°C, MDMA-induced neurotoxicity was evident and correlated with elevated core body temperature.
Conclusions:
- Ambient temperature significantly modulates MDMA neurotoxicity and thermoregulation in rats.
- Increased core body temperature exacerbates MDMA neurotoxicity.
- Findings suggest implications for understanding MDMA's mechanism of action and the risks of hyperthermia associated with human MDMA use.