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

Abstract

Binge drinking during adolescence can have behavioral and neurobiological consequences. We have previously found that adolescent intermittent ethanol (AIE) exposure produces a sex-specific social impairment in rats. The prelimbic cortex (PrL) regulates social behavior, and alterations within the PrL resulting from AIE may contribute to social impairments. The current study sought to determine whether AIE-induced PrL dysfunction underlies social deficits in adulthood. We first examined social stimulus-induced neuronal activation of the PrL and several other regions of interest implicated in social behavior. 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 cFos, activated cells that express of β-gal can be inactivated by Daun02. β-gal expression in most ROIs was elevated in socially tested adult rats relative to home cage controls, regardless of sex. However, differences in social stimulus-induced β-gal expression between controls and AIE-exposed rats was evident only in the PrL of males. A separate cohort underwent PrL cannulation surgery in adulthood and were subjected to Daun02-induced inactivation. Inactivation of PrL ensembles previously activated by a social stimulus led to a reduction of social behavior in control males, with no changes evident in AIE-exposed males or females. These findings highlight the role of the PrL in male social behavior and suggest an AIE-associated dysfunction of the PrL may contribute to social deficits following adolescent ethanol exposure.

Prelimbic cortex perineuronal net expression and social behavior: Impact of adolescent intermittent ethanol exposure

“…We previously found differential activation of the PrL between water- and AIE-exposed males (Towner et al, 2023), however, in the current study, β-gal+ cell counts in the PrL were similar in water-exposed and AIE-exposed males. This discrepancy between the two studies is likely due to methodological differences.…”

“…If these activated PV interneurons contribute to social deficits it is therefore not surprising that differences in WFA and β-gal colocalization were absent in females. The role of the PrL in regulating social investigation may be sex-specific, a possibility supported by our previous findings of PrL inactivation reducing social investigation in male rats but not their female counterparts (Towner et al, 2023). Similarly, chemogenetic inhibition of the basolateral amygdala to PrL circuit has been found to reduce social investigation in males but not females (Przybysz et al, 2023).…”

“…1B-D). Brain tissue was collected from adult males and female rats exposed to either water or AIE, with all animals exposed to social partners for 60 minutes, with AIE-exposed males demonstrating social deficits indexed via significant decreases in social investigation (see: Towner et al, 2023). A 2 (adolescent exposure) X 2 (sex) ANOVA of the number of WFA+ cells revealed a significant adolescent exposure by sex interaction, F (1,47) = 5.01, p < 0.05.…”

“…To determine whether AIE leads to an upregulation of PNN expression in the PrL, we conducted histology on tissue generated in a previous study (Towner et al, 2023). This experiment used a 2 adolescent exposure (water, AIE) x 2 sex (male, female) design with 10 – 14 LacZ+ animals per group.…”

“…Our lab has repeatedly found that AIE exposure induces social deficits specifically in male rats, with no changes evident in females (Dannenhoffer et al, 2018; Towner et al, 2022a; Varlinskaya et al, 2020; Varlinskaya et al, 2014). We recently identified socially evoked neuronal activity within the prelimbic cortex (PrL) was lower in AIE-exposed males compared to water-exposed controls (Towner et al, 2023). To determine whether this altered activation state was functionally related to AIE-induced social deficits, we used a pharmacogenetic approach that allows inactivation of previously activated PrL neuronal ensembles with Daun02 in cFos-LacZ rats.…”