Social instability stress in adolescent male rats reduces social interaction and social recognition performance and increases oxytocin receptor binding

Predictors of social instability stress effects on social interaction and anxiety in adolescent male rats

“…Consistent with our previous report (Hodges et al, ), in experiment 1, SS rats spent less time in social interaction with unfamiliar peers than did CTL rats when tested on PND 46, 24 hr after the last stressor exposure. In experiment 2, we investigated anogenital sniffing separately from other social interaction, and contrary to our prediction, SS and CTL rats spent equal amounts of time in anogenital sniffing.…”

“…A reduction in social interaction may indicate social anxiety and/or an altered behavioral repertoire rather than a reduction in the reward value of peers. In keeping with this possibility, we have found that adolescent SS rats spent more time investigating unfamiliar peers when the peers were confined behind wire mesh (thus, social approach rather than social interaction) despite a reduction in social interactions with unconfined peers (Hodges et al, ). Further, in a social conditioned place preference task, SS rats found social interactions with unfamiliar peers as rewarding as did CTL rats (Hodges et al, ).…”

“…In keeping with this possibility, we have found that adolescent SS rats spent more time investigating unfamiliar peers when the peers were confined behind wire mesh (thus, social approach rather than social interaction) despite a reduction in social interactions with unconfined peers (Hodges et al, ). Further, in a social conditioned place preference task, SS rats found social interactions with unfamiliar peers as rewarding as did CTL rats (Hodges et al, ). The pattern of greater Fos‐ir cell counts in the nucleus accumbens of SS rats compared with CTL rats may reflect a greater reward value of social interactions in SS rats.…”

“…Total time spent in social interaction during the 15 min test session for each rat was measured by an experimenter blind to the Stress Group conditions. Social interaction included social play, anogenital sniffing, allogroom, following, investigation, as defined in Cirulli, Terranova, and Laviola () and as in our previous research (Hodges et al, ). Social interaction test sessions were conducted in dim red light between 1 and 5 hr after the onset of the dark phase.…”

“…Thus, the quality of social relationships during the adolescent period may alter the developmental trajectory of brain regions involved in social behavior and thereby alter social behavior. We previously reported that SS rats had enhanced oxytocin receptor binding density in the lateral septum and nucleus accumbens compared with non‐stressed controls (Hodges et al, ). Oxytocin is a neuropeptide that acts on central receptors to regulate several aspects of social behavior, such as social interaction and social recognition (Dumais, Alonso, Bredewold, & Veenema, , 2016b; reviewed in Dumais & Veenema, ).…”