Female rats readily learn to self-administer the stimulants mephedrone, methylone, and MDMA, with mephedrone-trained animals taking significantly more drug infusions than the other groups. When the dose was varied under fixed-ratio or progressive-ratio schedules, all three drugs showed similar potency within each training group. Mephedrone-trained rats continued to take more of any drug during dose substitution, suggesting lasting effects of the initial training drug. Abuse liability of these compounds is predicted to be similar in experienced stimulant users but may differ if one is the first drug used.
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.