The same stress has divergent effects on social versus asocial manifestations of anxiety-like behavior over time

Abstract

Stress may lead to augmented anxiety, which may, with time culminate in some form of anxiety disorder. Behavioral alterations related to increased anxiety can be broadly classified into two types–social, affecting interactions between individuals, and self-oriented, affecting the anxious individual only. While a growing body of literature now exists describing the effects of stress-induced anxiety on self-oriented behavior in animal models of anxiety disorders, the effects of such aberrant anxiety on social behavior has largely remained uncharacterized in these models. This study aims to fill this gap in our understanding by examining changes in social behavior following a single 2-hour episode of immobilization stress, which has been shown to cause delayed structural and functional changes in the amygdala. To this end, we examined social behavior, measured as active social interactions, anogenital sniffing, nose-to-nose contacts, allogrooming, actively following and crawling under, as well as self-oriented asocial behavior, manifested as self-grooming and rearing, in adult male rats. Stressed animals showed reduced social interaction 1 day after immobilization stress and this decrease was persistent for at least 10 days after stress. In contrast, individualistic behaviors were impaired only 10 days, but not 1 day later. Together, these results not only show that the same single episode of stress can elicit divergent effects on social and asocial measures of anxiety in the same animal, but also suggest that enhanced social anxiety soon after stress may also serve as an early indicator of its delayed behavioral effects.