Molecular substrates of social avoidance seen following prenatal ethanol exposure and its reversal by social enrichment.

Prenatal ethanol exposure is associated with, and is a risk factor for, developmental disorders with abnormal social behaviors, including autism spectrum disorders. We hypothesize that the specific effects of ethanol on social behavior are defined by the timing of the exposure as well as subsequent changes in brain regions such as the amygdala and ventral striatum. We recently reported that in utero ethanol exposure on gestational day 12 alters social behaviors of weanling [postnatal day (P) 28], adolescent (P42), and young adult (P75) rats. Male, but not female, offspring of the ethanol-exposed dams showed significant decreases in social investigation (sniffing of a social partner), contact behavior (grooming or crawling over/under the partner), and play fighting (following, chasing, nape attacks, or pinning) at all ages tested with maximal effects at P28 and P42. Furthermore, ethanol-exposed males and females showed evidence of social avoidance at P42 and P75. The present study sought to test whether a form of social enrichment could normalize any of the social deficits and what the molecular mechanisms of such effects might be. We found that housing rats with nonmanipulated control rats normalized the social avoidance phenotype normally seen when they are housed with sex-matched prenatal ethanol-exposed littermates. There was no mitigation of the other ethanol-induced behavioral deficits. Conversely, male control-treated rats housed with nonlittermates showed deficits in play fighting, social investigation and contact behavior. Molecular analyses of the amygdala and ventral striatum of adolescent rats following fetal ethanol exposure indicated several specific neurotransmitter systems and pathways that might underlie the social avoidance phenotype as well as its reversal.