Adolescent social stress increases anxiety-like behavior and ethanol consumption in adult male and female C57BL/6J mice

Abstract

Exposure to social stress is an important risk factor for comorbid affective disorders and problem alcohol use. To better understand mechanisms involved in social stress-induced affective disorder and alcohol use co-morbidity, we studied the effects of adolescent social stress on anxiety- and depression-like behaviors and binge-like ethanol consumption. Male and female C57BL/6J mice were exposed to chronic variable social stress (CVSS) or control conditions throughout adolescence (postnatal days, PND, 25-59) and then tested for anxiety-like behavior in the elevated plus maze and a novel open field environment, or depression-like behavior using the forced swim test on PND 64-66. Mice were then tested for binge-like ethanol consumption using the Drinking-in-the-Dark model. Male and female mice exposed to adolescent CVSS had increased adult anxiety-like behavior and increased locomotor adaptation to a novel environment. Further, CVSS mice consumed significantly more ethanol, but not saccharin, than controls. Despite group differences in both anxiety-like behavior and ethanol consumption, there was no relationship between these outcomes within individual mice. These data suggest that exposure to adolescent social stress is an important risk factor for later alcohol use and affective behaviors, but that social stress does not necessarily dictate co-morbidity of these outcomes.

Figure 1

Adolescent CVSS increased anxiety-like behavior in adult males and females. Data (mean ± SEM) represent (A) percent time spent on the open arms of the EPM, (B) number of closed arm entries on the EPM, (C) total distance traveled in the OFT, and (D) time spent immobile in the FST. Significant main effect of stress condition: **p < 0.01. (n = 9–15/group).

Figure 2

Adolescent CVSS increased binge-like ethanol consumption in adult males and females. Data (mean ± SEM) represent (A) ethanol consumption, (B) blood ethanol concentrations (BEC), and (C) saccharin consumption. Significant time x stress condition interaction: *p < 0.05. Significant sex x stress condition interaction: ^#p < 0.05. n = 9–15/group. Data for males and females are combined for ethanol and saccharin consumption.