lsolation in the social environment,such as pair-bond disruption,is stressful and can induce various behavioral and neuralchemical changes in the distressed animal.We conducted a series of experiments to test the hypothesis that long-term pair-bond disruption affects neurochemicals and alters behavior in the monogamous prairie vole (Microtus ochrogaster).In behavior domain,disrupted males displayed higher levels of anxiety-like behaviors in the elevated plus maze and dark light box tests and depression-like behavior in the forced swim test than control males.Further,disrupted males showed an increased level of affiliative behaviors and a decreased level of aggressive behaviors compared to controls in the social affiliative test and resident-intruder tests.In neurochemicals domain,pair-bond disruption increased vasopressin (AVP),oxytocin (OT),corticotrophin releasing hormone (CRH),and tyrosine hydroxylase (TH) in the paraventricular nucleus of the hypothalamus (PVN) but not in SON.Together,our data suggest that pair-bond disruption not only alters anxiety-like,depression-like,and affiliative behaviors m a behavior-specific manner but also significantly increases cell densities in selected brain region highlighting a possible link between altered neurochemicals within the limbic system and behavioral changes in adult disrupted male prairie voles.