Social Interaction With an Alcohol-Intoxicated or Cocaine-Injected Peer Selectively Alters Social Behaviors and Drinking in Adolescent Male and Female Rats.

Abstract

Drinking alcohol is facilitated by social interactions with peers, especially during adolescence. The importance of peer social influences during adolescence on alcohol and substance use has recently received more attention. We have shown that social interaction with an alcohol-intoxicated peer influences adolescent alcohol drinking differently in male and female rats using the demonstrator-observer paradigm. The present set of experiments analyzed the social interaction session to determine changes in social behaviors and subsequent alcohol drinking in adolescent male and female rats. Specifically, in Experiment 1, we determined whether specific social behaviors were altered during interaction with an alcohol-intoxicated demonstrator administered 1.5g/kg ethanol (EtOH) and assessed changes in EtOH intake in adolescent observers. Experiment 2 examined changes in voluntary saccharin consumption to determine whether social interaction with an alcohol-intoxicated demonstrator administered 1.5g/kg EtOH altered consumption of a palatable solution. In Experiment 3, we administered saline, and a low (5mg/kg) or high (20mg/kg) dose of cocaine to the demonstrator and assessed changes in the adolescent observers to determine whether social interaction with a "drugged" peer altered social behaviors and voluntary EtOH intake. We showed that social interaction with an alcohol-intoxicated demonstrator administered 1.5g/kg EtOH (i) decreased social play and increased social investigation and social contact in adolescent male and female observers, (ii) did not alter nonsocial behaviors, (iii) did not alter saccharin consumption, and (iv) increased voluntary EtOH intake in adolescent female but not male observers. When the peer was injected with cocaine, (i) social play was dose-dependently decreased, (ii) there were no changes in other social or nonsocial behaviors, and (iii) voluntary EtOH intake in adolescent male and female observers was unaffected. The present results are consistent and extend our previous work, showing that social interaction with an alcohol-intoxicated peer selectively alters social behaviors and alcohol drinking in adolescent rats. Females appear to be more sensitive to the elevating effects of social interaction on voluntary EtOH consumption.