Anxiety response and restraint-induced stress differentially affect ethanol intake in female adolescent rats

Abstract

Anxiety disorders are more likely to occur in women than in men, usually emerge during adolescence and exhibit high comorbidity with alcohol use disorders (AUD). Adolescents with high levels of anxiety or heightened reactivity to stress may be at-risk for developing AUD. An approach to analyze if high levels of inborn anxiety predict greater ethanol drinking is to assess the latter variable in subjects classified as high- or low-anxiety responders. The present study assessed ethanol drinking in adolescent, female Wistar, rats classified as high-, low- or average-anxiety responders and exposed or not to restraint stress (RS, Exp. 1). Classification was made through a multivariate index derived from testing anxiety responses in an elevated plus maze and a light-dark box tests. RS was applied after animals had been initiated to ethanol drinking. Intake of sweetened ethanol was unaffected by level of anxiety response. Adolescents with high levels of inborn anxiety exhibited significantly higher intake of unsweetened ethanol than counterparts with standard levels of anxiety, yet this effect was inhibited by RS exposure. Experiment 2 assessed FOS immunoreactivity after RS. Stress induced a significant increase in FOS immunoreactivity at the paraventricular nucleus, yet this effect was unaffected by level of anxiety response. Female adolescents with high levels of basal anxiety may be at-risk for exhibiting increased predisposition for ethanol intake and preference. The study also indicates that stress may exert differential effects on adolescent ethanol intake as a function of the level of anxiety response.

Keywords: Fos immunoreactivity; adolescents; anxiety; ethanol intake; stress.