Behavioral Effects of 4-CMC and 4-MeO-PVP in DBA/2J Mice After Acute and Intermittent Administration and Following Withdrawal from Intermittent 14-Day Treatment

Synthetic cathinones appeared on the market in the 2000s as new psychoactive substances and gained significant prevalence among drug abusers. Cathinones produce psychostimulant and empathogenic effects by enhancing dopaminergic, noradrenergic, and serotoninergic neurotransmission in the brain, and those which potently and selectively enhance dopaminergic transmission are considered to have higher abuse potential. The present study examines the behavioral effects related to psychostimulant properties, abuse potential, and addiction in DBA/2J mice of two cathinones with different profile of action on monoamine system, 4-chloromethcathinone (4-CMC), and 4-methoxy-pyrrolidinopentiophenone (4-MeO-PVP). 4-CMC and 4-MeO-PVP increase spontaneous locomotor activity after acute treatment and produce behavioral sensitization after 7-day intermittent treatment, which is a common feature of drugs of abuse. 4-MeO-PVP, but not 4-CMC, produces conditioned place preference after 4 days, indicating its rewarding properties. Finally, the ability of 4-CMC and 4-MeO-PVP to induce withdrawal symptoms after discontinuation from 14-day treatment was assessed using a battery of tests for behavioral markers of depression in mice: a tail suspension test, a forced swim test, measuring despair, and a sucrose preference test, measuring anhedonia. None of the three tests revealed increased depressive symptoms. Moreover, neither spontaneous locomotor activity nor motor performance on a rotarod was impaired after 14-day treatment with the tested compounds. These results indicate that 14-day treatment of mice with 4-CMC or 4-MeO-PVP does not induce significant withdrawal symptoms after cessation, nor significant impairment of dopaminergic circuitry resulting in motor impairment. The current study shows that 4-CMC and 4-MeO-PVP produce abuse-related behavioral changes in mice, which are more pronounced after more dopamine-selective 4-MeO-PVP.