Binge-like Acquisition of α-pyrrolidinopentiophenone (α-PVP) Self-Administration in Female Rats
The synthetic cathinone -pyrrolidinopentiophenone (-PVP) has been associated with violent and/or bizarre public behavior in users. Association of such behavior with extended binges of drug use motivates additional investigation, particularly since a prior study found that half of male rats experience a binge of exceptionally high intake, followed by sustained lower levels of self-administration during the acquisition of intravenous self-administration (IVSA) of a closely related drug, 3,4-methylenedioxypyrovalerone. The binge-like acquisition pattern appeared to be novel for rat IVSA, thus the present study was designed to determine if this effect generalizes to IVSA of -PVP in female rats. Female Wistar rats were trained in IVSA of -PVP (0.05 mg/kg/inf) in experimental chambers that contained an activity wheel. Groups of animals were trained with the wheels fixed (No-Wheel group), fixed for the initial 5 days of acquisition or free to move throughout acquisition (Wheel group). The groups were next subjected to a wheel-access switch and then all animals to dose-substitution (0.0125-0.3 mg/kg/inf) with the wheels alternately fixed and free to move. Approximately half of the rats initiated their IVSA pattern with a binge day of exceptionally high levels of drug intake, independent of wheel access condition. Wheel activity was much lower in the No-Wheel group in the wheel switch post-acquisition. Dose-effect curves were similar for wheel-access training groups, for binge/no binge phenotypic subgroups and were not altered with wheel access during the dose-substitution. This confirms the high reinforcer efficacy of -PVP in female rats and the accompanying devaluation of wheel activity as a naturalistic reward.