The Short-Term and Long-Term Effects of Stressors on the Acquisition of Cocaine-Induced Conditioned Place Preference

Abstract

The short-term and long-term modulating effects of exposure to stressors on the acquisition of cocaine-induced conditioned place preference (CPP) were examined in this study. Unconditioned foot shock was used immediately before each conditioning of cocaine-induced CPP to study the short-term modulating effect of stress on the acquisition of cocaine-induced CPP. Nonetheless, a combined stress procedure was used 4 weeks prior to the cocaine-induced CPP to examine the long-term effect of stress on the acquisition of this memory. We found that foot shock stressor did not acutely affect cocaine-induced CPP as extremely low (2.5 mg/kg/conditioning) or high (10 mg/kg/conditioning) dose of cocaine was used as conditioning dosage. In contrast, foot shock stress significantly decreased cocaine (5 mg/kg/conditioning)-induced CPP. Interestingly, a combined unconditioned foot shock and restraint in water stressor drastically increased cocaine (5 mg/kg/conditioning)-induced CPP. The implication of the latter result is that pre-exposure to a potent stressor may enhance the appetitive effect of cocaine in a long-term manner.