Determining the neuronal ensembles underlying sex-specific social impairments following adolescent intermittent ethanol exposure.

Binge drinking during adolescence can have behavioral and neurobiological consequences. We have previously found that adolescent intermittent ethanol (AIE) exposure produces sex-specific social alterations indexed via decreases of social investigation and/or social preference in rats. The prelimbic cortex (PrL) regulates social interaction, and alterations within the PrL resulting from AIE may contribute to social alterations. The current study sought to determine whether AIE-induced PrL dysfunction underlies decreases in social interaction evident in adulthood. We first examined social interaction-induced neuronal activation of the PrL and several other regions of interest (ROIs) implicated in social interaction. Adolescent male and female cFos-LacZ rats were exposed to water (control) or ethanol (4 g/kg, 25% v/v) via intragastric gavage every other day between postnatal day (P) 25 and 45 (total 11 exposures). Since cFos-LacZ rats express β-galactosidase (β-gal) as a proxy for Fos, activated cells that express of β-gal can be inactivated by Daun02. In most ROIs, expression of β-gal was elevated in socially tested adult rats relative to home cage controls, regardless of sex. However, decreased social interaction-induced β-gal expression in AIE-exposed rats relative to controls was evident only in the PrL of males. A separate cohort underwent PrL cannulation surgery in adulthood and was subjected to Daun02-induced inactivation. Inactivation of PrL ensembles previously activated by social interaction reduced social investigation in control males, with no changes evident in AIE-exposed males or females. These findings highlight the role of the PrL in male social investigation and suggest an AIE-associated dysfunction of the PrL that may contribute to reduced social investigation following adolescent ethanol exposure.