Differences in the social consequences of ethanol emerge during the course of adolescence in rats: social facilitation, social inhibition, and anxiolysis.

The present experiments explored social consequences of ethanol during adolescence by examining dose-dependent ethanol-induced social facilitation and inhibition in a non-anxiogenic (familiar) environment, and ethanol-related anxiolysis in an anxiogenic (unfamiliar) environment in early (P28) and late (P42) adolescent rats. Pronounced age-related differences in the social consequences of ethanol emerged during the course of adolescence, with early adolescents being uniquely sensitive to activating effects of low doses of ethanol when tested in the familiar context in terms of play fighting-an adolescent-characteristic form of social interactions, but conversely less sensitive than late adolescents to ethanol-associated social suppression when tested at higher ethanol doses in this context. Early adolescents were also less sensitive than late adolescents to the anxiolytic effects of ethanol revealed in the unfamiliar test situation, when indexed in terms of increases in social investigation and the ethanol-induced transformation of social avoidance into social preference. Anti-anxiety properties of ethanol were found to be sex-dependent in older animals, with late adolescent females being more sensitive to ethanol anxiolysis than their male counterparts. Considerable ontogenetic differences in the social consequences of ethanol are evident even within the adolescent period, with early adolescence being a time of particularly pronounced adolescent-typical sensitivities to ethanol. (c) 2006 Wiley Periodicals, Inc. Dev Psyshobiol 48: 146-161, 2006.