Locomotor response to novelty does not predict cocaine place preference conditioning in rats.

Previous studies have demonstrated that rats showing a strong locomotor response to a novel environment have a greater locomotor response to psychostimulant drugs and more rapidly acquire intravenous self-administration of amphetamine. In this report, we examined whether these high-responder (HR) rats would develop place-preference conditioning with cocaine more readily than low-responder (LR) rats. Neither group of rats developed conditioned place preference for cocaine, 2.5 mg/kg, intraperitoneally (IP). Both groups of rats developed conditioned place preference for cocaine, 5.0 and 15 mg/kg, IP. However, we could not find any evidence of enhanced conditioning in the HR rats. HR rats did show a greater locomotor response to cocaine, 15 mg/kg, IP, and the locomotor response of HR and LR rats to cocaine correlated with their response to a novel environment. We conclude that using the place-preference procedure, HR and LR rats do not differ in the rewarding effect of cocaine.