Renewal of cocaine seeking using social and nonsocial contextual stimuli

Rationale: Various nonsocial cues have been used as stimuli to examine the contextual control of drug seeking behavior, but little is known about the role of social stimuli. Objectives: This study determined if renewal of cocaine seeking is differentially controlled using a context consisting of either a social peer and/or house light illumination. Methods: In Experiment 1, male and female rats trained to self-administer cocaine in the presence of a same-sex social peer and house light illumination (context A). Following self-administration, rats were randomly assigned to either an AAA (control) or ABA (renewal) group for extinction. For AAA rats, extinction consisted of the same context A as self-administration; for ABA rats, extinction occurred without the peer or house light (context B). Following extinction, renewal of cocaine seeking occurred by testing the peer alone, house light alone, and the peer + house light combination. Experiment 2 was conducted to ensure that the house light alone was sufficiently salient to produce renewal. Results: Both experiments showed that rats acquired cocaine self-administration and extinguished lever pressing. In Experiment 1, the ABA group renewed cocaine seeking to the peer and peer + house light, but not to the house light alone. In Experiment 2, ABA rats renewed cocaine seeking to the house light alone, indicating it was sufficiently salient to produce renewal. The AAA group did not show renewal in either experiment. Conclusion: Social peers serve as powerful stimuli that can overshadow nonsocial visual stimuli in the renewal of cocaine seeking.