Recreational use of the synthetic cathinones mephedrone (4-MMC) and MDPV is increasing, with reports of severe symptoms and deaths, but laboratory research on their effects is limited. In male Wistar rats, MDPV and methamphetamine produced a biphasic pattern of voluntary wheel running—higher activity at low doses and lower activity at the highest dose—while 4-MMC and MDMA caused dose-dependent reductions in activity. These results mirror the drugs' known effects on dopamine and serotonin neurotransmission, suggesting MDPV acts as a typical stimulant and 4-MMC resembles the entactogen MDMA, which may predict different abuse patterns and toxicities.
In rats, high ambient temperature (30°C) increases the acquisition of intravenous self-administration of MDMA more than low temperature (20°C). Initially, MDMA caused similar hypothermia in both temperature groups, but this effect diminished over training in the hot group. Activity levels, initially lower in the hot group, became similar by the end of training. When temperature conditions were swapped, rats trained in the hot condition increased MDMA intake under cold, while those trained in the cold modestly decreased intake under hot. Rats with higher MDMA intake showed blunted hypothermia after non-contingent MDMA. High temperature alone raised brain reward thresholds, and MDMA lowered thresholds below baseline only at low temperature. The findings suggest that high temperature enhances MDMA self-administration acquisition through an aversive effect rather than thermoregulatory motivation.