Sensitization to the locomotor stimulant effects of "bath salt" constituents, 4-methylmethcathinone (4-MMC) and 3,4-methylenedioxypyrovalerone (MDPV), in male Sprague-Dawley rats.

Background: Synthetic cathinones, 4-methylmethcathinone (4-MMC) and 3,4-methylenedioxypyrovalerone (MDPV), serve as a substrate or blocker at monoaminergic transporters, respectively, and produce locomotor stimulant effects in rodents. The present study investigated in rats the effects of repeated exposure to 4-MMC, MDPV, or mixtures of the two on the induction of locomotor sensitization and expression of cross-sensitization to cocaine.

Methods: Seventy-two male Sprague-Dawley rats received daily intraperitoneal injections of saline, MDPV (0.