Persistent inflammation does not promote aversion-resistant binge-like alcohol drinking in rats

Background: Chronic pain is a leading cause of disability, significantly decreases quality of life, and is highly co-morbid with substance use disorders, including alcohol use disorder (AUD). This is due, in part, to the pain-relieving effects of alcohol acting as a potential driving force for the progression and maintenance of AUD. Despite a substantial body of historic, anecdotal, clinical, and epidemiological evidence supporting the analgesic efficacy of alcohol, few preclinical studies have investigated the effects of pain on volitional alcohol drinking. Further, no studies to date have investigated aversion-resistant drinking in the context of persistent pain. Methods: To address this gap in the literature, the current study combined quinine adulteration with the drinking in the dark (DID) model of binge-like alcohol drinking to assess the effects of complete Freund's adjuvant (CFA)-induced persistent inflammation on aversion-resistant binge-like alcohol drinking in female and male Long Evans rats. Results: Consistent with previous findings from our laboratory, CFA did not affect binge-like alcohol drinking in either sex, although female rats did consume greater levels of alcohol during baseline and post-CFA DID sessions. Similarly, CFA did not affect quinine adulterated binge-like alcohol drinking in either sex. Conclusions: This study is the first to investigate the impact of persistent inflammation on aversion-resistant alcohol drinking. Although we found no effects of CFA on quinine adulterated binge-like alcohol drinking, these findings provide the groundwork for future investigations into this otherwise unstudied aspect of the pain-alcohol relationship.