MDMA (ecstasy) dose-dependently increased body temperature and decreased serotonin levels in heart tissue of rats. The drug altered cardiac metabolites, increasing carnitine while decreasing choline, with no change in other energy-related compounds. These effects suggest MDMA disrupts energy regulation in heart tissue, potentially shifting metabolism toward fatty acid use, and affects cardiovascular serotonergic signaling.
Repeated low doses of MDMA (2.5 mg/kg) caused mild anxiety-like behavior in rats one day after exposure, but this effect was confounded by reduced movement and did not persist at 15 days. Higher doses (5 mg/kg) did not produce anxiety-like behavior. Sucrose preference, a measure of anhedonia, increased over time and was unaffected by MDMA or sex. Brain analysis showed reduced serotonin levels in the nucleus accumbens one day after both MDMA doses, but not in the prefrontal cortex or dorsal hippocampus. These transient effects suggest that low-dose MDMA used clinically may be tolerated without limiting therapeutic benefit.