Chronic Alcohol Drinking Drives Sex-Specific Differences in Affective Behavior and Medial Prefrontal Cortex Activity in CRF1:Cre:tdTomato Transgenic Rats

Abstract

In 2021, 131 million adult Americans reported drinking alcohol in the last month, despite the well-known consequences of alcohol consumption. While alcohol use disorders are associated with both mood and chronic pain disorders, the relationship between alcohol drinking and affective and nociceptive behaviors remains unclear. Corticotropin releasing factor receptor-1 (CRF1) has been implicated in alcohol drinking, affective states, and pain sensitivity; often in a sex-dependent manner. In order to probe the effects of alcohol drinking on activity of CRF1+ cells and to also test the hypothesis that alcohol drinking is associated with both basal and subsequent affective and nociceptive readouts, we put male and female CRF1:cre:tdTomato rats through a battery of behavioral tests before and after intermittent access to alcohol. Following baseline testing, rats began alcohol (or water) drinking. Females consumed more alcohol in the first week, but there was no effect of sex on overall alcohol intake. Following 3-4 weeks of drinking, behavioral tests were repeated. Alcohol drinking decreased mechanical sensitivity, but no other effects of alcohol drinking were observed between experimental groups. Individual alcohol intake correlated with affective behavior in both sexes but only correlated with thermal sensitivity in males. There were no main effects of alcohol drinking or sex on CRF1+ neuronal activity in the medial prefrontal cortex but final session alcohol intake correlated with activity in CRF1+ neurons in the infralimbic subregion. Together, our results suggest complex interplay between affective state, alcohol drinking, and the role of prefrontal CRF1+ neurons in mediating these behaviors.SIGNIFICANCE STATEMENTDespite alcohol use being extremely comorbid with mood and pain disorders, there is still a limited understanding of the interaction and directionality between the them. To investigate this problem, rats were tested for affective behavior before and after being allowed to drink alcohol for 6 weeks. While baseline behavior did not predict subsequent intake, alcohol intake predicted subsequent affective behavior on an individual subject basis. These findings were accompanied by increased activity of the corticotropin releasing factor 1 containing neurons in the infralimbic region of the prefrontal cortex. Together, these findings reveal a new mechanism for understanding alcohol use.