Social experience during adolescence in female rats increases 50 kHz ultrasonic vocalizations in adulthood, without affecting anxiety‐like behavior

Abstract

Adolescents are highly motivated to engage in social interactions, and researchers have hypothesized that positive social relationships during adolescence can have long term, beneficial effects on stress reactivity and mental well‐being. Studies of laboratory rodents provide the opportunity to investigate the relationship between early social experiences and later behavioral and physiological responses to stressors. In this study, female Lister‐hooded rats (N = 12 per group) were either (a) provided with short, daily encounters (10 min/day) with a novel partner during mid‐adolescence (postnatal day 34–45; “social experience,” SE, subjects) or (b) underwent the same protocol with a familiar cagemate during mid‐adolescence (“control experience,” CE, subjects), or (c) were left undisturbed in the home cage (non‐handled “control,” C, subjects). When tested in adulthood, the groups did not differ in behavioral responses to novel environments (elevated plus maze, open field, and light‐dark box) or in behavioral and physiological (urinary corticosterone) responses to novel social partners. However, SE females emitted significantly more 50 kHz ultrasonic vocalizations than control subjects both before and after social separation from a familiar social partner, which is consistent with previous findings in male rats. Thus, enhanced adolescent social experience appears to have long‐term effects on vocal communication and could potentially modulate adult social relationships.

Suppression of ovarian hormones in adolescent rats has no effect on anxiety‐like behaviour or c‐fos activation in the amygdala

“…In the present study, control male and control female subjects did not differ in the amount of time spent in the exposed sections of each apparatus, which could potentially be explained by the handling that subjects received during adolescent testing. Adolescent handling has been shown to reduce later anxiety‐like behaviour, 87 whereas adolescent social interactions per se do not alter behavioural responses on these tasks 88 . The lack of sex differences in control subjects leaves open the possibility that the effects of suppressing the HPG axis might only be revealed following specific adolescent experiences.…”

Shaped by you: The effect of social partner on cortisol and behavior during adolescence in a female rodent

“…It has not yet been investigated in female guinea pigs whether cues from the social environment shape behavior and hormone profiles during adolescence. Existing studies which experimentally manipulate the social environment of female mammals during adolescence have been largely restricted to social stressors such as social isolation and social instability in laboratory rodents (Burke et al., 2017; Emmerson et al., 2020; McCormick et al., 2008; Rivera‐Irizarry et al., 2020; Romeo et al., 2016; Varlinskaya et al., 1999; Ver Hoeve et al., 2013).…”