Sex Differences in Aversion-Resistant Ethanol Intake in Mice

Abstract

Abstract Aims Compulsive ethanol intake, characterized by persistent consumption despite negative consequences, is an addictive behavior identified by the DSM-5 as a central criterion in diagnosing alcohol use disorders (AUD). Epidemiological data suggest that females transition from recreational alcohol use to AUD more rapidly than males. Because of this potential sex difference in the etiology of AUD, it is critical to assess addictive behaviors such as compulsive intake in both males and females in preclinical studies. Methods We used the model of aversion-resistant ethanol consumption to assess compulsive-like ethanol intake. In these experiments, C57BL6/J mice were first provided with continuous access two-bottle choice between water and ethanol to establish baseline intake. Ethanol solution was then adulterated with increasing concentrations of the bitter tastant quinine hydrochloride. Animals that consume ethanol solution despite its pairing with this negative stimulus are thought to be exhibiting compulsive-like behavior. Results We found that higher concentrations of quinine were required to suppress ethanol consumption in female mice relative to males. We found no effect of estrous cycle phase on baseline ethanol intake or on quinine-adulterated ethanol intake in females. Conclusions Collectively, these data suggest that females exhibit a higher degree of aversion-resistance than male mice. Because we observed no effect of estrous cycle phase, it is likely that the presence of threshold levels of estradiol or progesterone, as opposed to their natural fluctuation across the estrous cycle, mediates increased aversion-resistance in females. Alternatively, or in combination, developmental effects of sex hormones could contribute to aversion-resistant ethanol intake.