Automated home-cage sipper devices reveal age and sex differences in ethanol consumption patterns

Abstract

BackgroundAlcohol consumption and alcohol use disorder (AUD) are influenced by circadian rhythms. Alcohol-related behaviors and circadian rhythms differ with age and sex, but little preclinical research has compared circadian patterns of ethanol consumption across ages and sexes. Cost-effective tools are becoming widely available that could elucidate these patterns, including open-source, Arduino-based home-cage sipper devices. We hypothesized these devices would reveal age- and sex-specific patterns of ethanol and water consumption and ethanol-induced changes in overall fluid consumption rhythms. MethodsWe used Arduino-based home-cage sipper devices in a continuous-access two-bottle choice (2BC) paradigm with water and ethanol (10% v/v) for 14 days to measure drinking patterns of male and female adolescent (3-week), young adult (6-week), and mature adult (18-week) C57BL/6J mice. Grams per kilogram (g/kg) fluid consumption were manually recorded at the beginning of each dark cycle, while sipper devices continuously recorded drinking. ResultsManually collected 2BC data confirmed greater ethanol consumption in females of all age groups as well as stepwise decreases in total fluid consumption with age in ethanol-exposed females and in both sexes in the water-only groups. Correlations of manually recorded versus sipper count data were strong and significant for ethanol, but modest for water, suggesting fluid differences in drinking microstructure. Blood ethanol concentrations were significantly correlated with sipper data, indicating sipper devices accurately determine temporal ethanol consumption. Sipper devices uncovered subtle differences in circadian rhythms by age, group, and ethanol exposure, including minor phase advancement in ethanol consumption with age in females, but delay in males, as well as a female-specific phase delay and weaker amplitude in total fluid consumption across age groups with ethanol exposure. ConclusionsWe show these devices capture circadian patterns of ethanol drinking behavior that differ by age, sex, and ethanol exposure inaccessible by manual 2BC measurements alone. Future studies may examine older age groups and further dissect circadian drinking patterns by age and sex and their molecular mechanisms relevant to AUD pathogenesis.