Acute alcohol exposure dose-dependently alleviates social avoidance in adolescent mice and inhibits social investigation in adult mice

Background. Motivations for alcohol consumption often focus on ethanol’s purported prosocial effects: social enhancement and reduction of socially focused anxiety. Despite substantial research supporting prosocial effects, contrary research exists demonstrating alcohol-elicited antisocial and asocial behaviours. Additionally, evidence typically fails to delineate whether alcohol-induced prosocial effects are due to alcohol expectancies or pharmacological actions of ethanol. Studies exploring ethanol’s pharmacological effects on social behaviour and factors that modulate apparent contradictory prosocial versus asocial effects are lacking. Objectives. This study investigated whether factors of age, ethanol dose and social fear modulate ethanol-induced pharmacological effects on sociability and social anxiety–like avoidance. Methods. Experiments examined the acute effects of ethanol doses (0, 0.25, 0.8, 1.6 g/kg; i.p.) in adult (10-week-old) and adolescent (PND 31–33) C57BL/6J male mice on social interaction using a social fear conditioning paradigm. Control experiments assessed whether ethanol-induced effects were social-specific. Results. In adult mice, no specific effects of ethanol on social avoidance were observed at any dose. However, high-dose ethanol (1.6 g/kg) suppressed social approach in all adult mice. In contrast, low-dose ethanol (0.25 g/kg) alleviated social avoidance in adolescent mice and no social suppression was observed at higher ethanol doses. Thus, higher doses of ethanol impair social behaviour in adult mice, whereas lower doses specifically alleviate social anxiety–like avoidance in adolescent mice. Conclusions. Age, dose and social fear are critical modulators of acute ethanol-induced pharmacological effects on social behaviour. Inconsistencies in ethanol-induced social consequences appear at least partly mediated by pharmacological interactions—not solely alcohol expectancies.