Interaction of noncontingent cocaine and contingent drug-paired stimuli on cocaine reinstatement.

Both noncontingent cocaine and the presentation of cocaine-paired external stimuli will reinstate cocaine-appropriate operant responding. However, the interaction of noncontingent cocaine and cocaine-paired stimuli in producing reinstatement has not been extensively examined. In the present study, the ability of noncontingent cocaine alone, the combination of noncontingent cocaine + contingent cocaine-paired lights + tone and contingent lights + tone alone to produce reinstatement were examined. No cocaine dose (3, 10, 17 mg/kg) produced significant reinstatement in the absence of cocaine-paired lights + tone. When responding also resulted in lights + tone presentation, all doses of cocaine produced similar, significant reinstatement. Finally, when only response contingent lights + tone were presented, none of the groups showed significant reinstatement. These findings indicate that in isolation, noncontingent cocaine alone and cocaine-paired external stimuli may be insufficient to engender significant levels of reinstatement, but when presented together produce robust reinstatement. The results highlight the important interaction between drug administration and drug-paired environmental stimuli in the reinstatement model.