Adolescent Alcohol Induced Reductions in Choline Acetyltransferase Expression: Association with Sex and Behavioral Flexibility

<span style="font-weight: 400;"> </span><span style="font-weight: 400;">3.3 million adolescents aged 12-20 report binge alcohol consumption in the past month, according to the 2023 National Survey on Drug Use and Health (NSDUH). Preclinical work has shown that adolescent binge alcohol consumption is known to reduce choline acetyltransferase positive (ChAT+) neuron quantities within the basal forebrain, leading to reduced behavioral flexibility and adaptive decision making in adulthood. Previous studies have not yet investigated sex specific differences within adolescent alcohol induced ChAT+ reductions. Additionally, no studies have assessed functional connectivity and basal forebrain ChAT+ reductions due to binge adolescent alcohol exposure in the same individuals. To fill this gap, our lab exposed both male and female Sprague Dawley rats to AIE. Specifically, from postnatal day (P)25-54, adolescent rats received ethanol or water (5 g/kg) via gavage technique, on a 2-day-ON/2-day-OFF regimen. At adulthood (~P65), the rats were trained for 4 weeks using a Pavlovian conditioned approach. They additionally underwent a 2-week attentional set shifting task (ASST). Post behavioral training, the rats&nbsp; underwent resting state functional magnetic resonance imaging (fMRI) using a 9.4T magnet for a whole-brain analysis. Immunohistochemical analysis was then performed on basal forebrain slices, focusing on the medial septal (MS) nuclei to visualize ChAT+ density. Within ASST collapsed across sex, AIE did not significantly alter the total trials required for initial acquisition.&nbsp; Within reversal 1, AIE rats showed significant alterations in active, prepotent, and subsequent errors (p &lt; 0.05). Reversal 2 showed significant alterations in total trials as well as prepotent, initial errors ( p&lt; 0.05) active, regressive, and subsequent errors (p &lt; 0.001). Our analysis of ChAT+ quantities revealed a highly significant effect of condition on neuron count, reinforcing previous literature (p &lt; 0.001). Additionally, we identified a novel and significant interaction between sex by exposure (p = 0.04). While the main effect of sex was only marginally significant (p = 0.078), the stronger sex by exposure interaction suggests that there are sex-specific factors that play a key role in shaping the neurobiological effects of adolescent alcohol exposure. Ultimately, these findings highlight a path for the development of sex-specific interventions.</span>