The effects of adolescent stress on adult social behavior and basolateral amygdala GABAergic neurons with perineuronal nets depend on prenatal stress history

Developmental stress is a well-established risk factor for mental health disorders, yet the neural mechanisms underlying these outcomes remain incompletely understood. Inhibitory brain networks, particularly within the amygdala, are disrupted by stress and implicated in stress-related psychopathologies. Using a rodent model, the current study investigated the isolated and combined effects of prenatal and adolescent stress on adult social interactions and GABAergic neurons surrounded by perineuronal nets (PNNs) in the basolateral amygdala (BLA). Male and female rats were exposed to chronic variable stressors (CVS) prenatally (PS), during adolescence (AS), or during both prenatal and adolescent periods (PS+AS). In adulthood, all animals were tested for social behavior with same-sex weight-matched partners, and brains were collected for identification of BLA inhibitory neurons (GAD67 staining) and PNNs (Wisteria Floribunda Agglutinin staining). For social behavior, AS alone robustly increased social investigation in adulthood relative to non-stressed (NS) controls and animals exposed to combined PS+AS. PS+AS subjects did not significantly differ from NS controls, suggesting that prenatal stress exposure prevented adolescent stress-induced increases in adult social investigation. An analogous data pattern was observed in the BLA. AS alone decreased the number GAD67+ neurons surrounded by PNNs (co-labeled) relative to NS controls and subjects exposed to combined PS+AS. When the percentage of total GAD67+ neurons co-labeled with PNNs was assessed, both PS alone and AS alone reduced the proportion of GAD67+ neurons surrounded by PNNs, whereas combined PS+AS had no effect. Overall, these data suggest that prenatal stress exposure prevents adolescent stress-induced disruptions to perineuronal nets surrounding inhibitory neurons in the BLA, potentially conferring resilience to adolescent stress-induced changes in inhibitory function and social behavior.