Acute novel stressors modify ethanol intake of psychosocially stressed rats

Abstract

Psychosocial stressors are known to alter ingestion of ethanol in humans and experimental animals. We evaluated the effect of novel acute stressors on ethanol ingestion of male triad-housed rats. Based on behavioral and body weight assessments triad members were designated as dominant, subdominant or subordinate rats, housed in triads designated as aggressive or non-aggressive triads. The triad-housed, and a group of single-housed rats, were sequentially subjected to three stressors (novel open field arena, elevated plus maze, and modified resident–intruder test) at 1–2 week intervals. Ethanol intake was measured for 21-h before and after each stressor. Prior to stressor exposure, ethanol intake of the triad-housed rats was higher than that of single-housed rats. In triads overall intake of ethanol was lower in dominant compared to non-dominant rats. The modified resident–intruder test decreased ethanol intake in non-dominant rats in aggressive triads, but increased its intake in non-aggressive triads. Since in non-dominant rats this stressor also increased ethanol preference but not total fluid intake, its effect on ethanol intake was specific. In non-dominant rats ethanol intake and preference declined after the elevated plus maze stressor, without an effect on total fluid intake, but water intake was increased only in the subdominant rats. Compared to triad-housed rats, single-housed rats were more resilient to the novel stressors. It can be concluded that novel acute stressors have specific effects on ethanol intake that are dependent on the subject's psychosocial stress level.