Long- vs short-access cocaine alters behavioral inhibition for cocaine in male rats.

Abstract

Impulsivity and behavioral inhibition are measures commonly associated with substance misuse, particularly cocaine use disorder. However, patterns of impulsive behaviors have been shown to differ based on cocaine use history and level of cocaine dependence. Extended cocaine access, which more closely models neural and behavioral changes that take place during the development of problematic cocaine use, has been shown to decrease behavioral inhibition in comparison to limited cocaine access. However, previous preclinical studies investigating these relationships have been mostly correlational and only utilize non-drug rewards. This study aims to utilize a differential rates of low reinforcement (DRL) schedule to investigate the impact of extended access to cocaine on behavioral inhibition toward a cocaine reinforcer. Male Sprague Dawley rats first self-administered intravenous cocaine infusions on a DRL schedule of reinforcement before being split into two groups: one given 6-h extended cocaine access (LgA) and one given 1-h short cocaine access (ShA) for 10 daily sessions. Following a washout period, the rats were placed back on DRL cocaine self-administration sessions. Results revealed that LgA rats showed impaired performance on the behavioral inhibition measure during the DRL self-administration sessions compared to baseline DRL performance and compared to ShA post-access behavioral inhibition measures. These results indicate that extended cocaine access impairs an organism's behavioral inhibition toward future cocaine use, indicating that those individuals with a history of heavy cocaine use will have impaired behavioral inhibition toward future cocaine use.