The interactive effects of environmental enrichment and extinction interventions in attenuating cue-elicited cocaine-seeking behavior in rats

Cues associated with cocaine can elicit craving and relapse. Attempts have been made to employ extinction therapy, which is aimed at attenuating the incentive motivational effects of cocaine cues, as a treatment for cocaine addiction; however, this approach has been largely unsuccessful perhaps due to the inability to extinguish all cues associated with cocaine use while in a clinic. Recently, environmental enrichment (EE) during abstinence has been proposed as a strategy to attenuate cue-elicited cocaine craving. The present study used an animal model to examine whether the utility of extinction toward attenuating cue-elicited cocaine-seeking behavior could be enhanced by also providing EE. All rats were trained to self-administer cocaine while housed in isolated conditions and then subsequently underwent 17 days of forced abstinence, during which they were either housed in pairs or under EE and they either received daily 1-h extinction sessions or similar handling without exposure to the self-administration environment. Following this intervention period, all rats were tested for cue-elicited cocaine-seeking behavior. To examine whether effects of these interventions persist, all rats were subsequently single-housed for an additional 7-day forced abstinence period, followed by a second test for cue-elicited cocaine-seeking behavior. We found that although daily extinction training and EE each attenuated subsequent cue-elicited cocaine-seeking behavior, the combined treatment of extinction training + EE completely prevented it. However, once these interventions were discontinued, their protective effects diminished. These findings suggest that combining behavioral therapy approaches may improve outcomes; however, future work is needed to improve the longevity of these strategies beyond their implementation.