Large individual differences were observed in the level of self-administration when MDPV was available under an FR5, but not PR, schedule of reinforcement. A history of responding for cocaine, but not food, inhibited the development of high levels of MDPV intake. ResultsĪ subset of rats responding for MDPV developed high levels of MDPV intake. Dose-response curves for MDPV were generated under FR5 and progressive ratio (PR) schedules of reinforcement. After 20 sessions, the cocaine- and food-history rats responded for MDPV for 20 additional sessions. Methodsįemale Sprague Dawley rats initially responded for MDPV (0.032 mg/kg/infusion), cocaine (0.32 mg/kg/infusion), or food (45-mg grain pellet) under fixed ratio (FR) 1 and FR5 schedules of reinforcement. ObjectivesĬharacterize the reinforcing potency and effectiveness of MDPV in female rats to determine whether (1) a subset of females also develop high levels of MDPV self-administration (i.e., a high-responder phenotype) and (2) the degree to which the high-responder phenotype is influenced by various reinforcement histories (i.e., responding for cocaine or food). A subset of male rats that self-administer 3,4-methylenedioxypyrovalerone (MDPV) have unusually high levels of drug intake however, factor(s) that influence this behavior (e.g., reinforcement history and sex) are unknown.

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