Effects of isolation after sexual experience on anxiety-like, depressive-like behaviors and affective states in male rats

Studies on social isolation have provided evidence for an enhanced anxiety-like phenotype, depressive-like symptoms and higher levels of 22-kHz ultrasonic vocalizations (USVs); whereas sexual experience could induce significant changes in affective states, decrease anxiety- and depressive-like responses. However, the behavioral and emotional alterations in male rats exposed to isolation after sexual experience remain poorly understood. Therefore, the present study examined anxiety- and depressive-like parameters, as well as USV emissions in male rats isolated for 1, 2, or 7 d following 1-week sexual (male-female paired housing) or social (male-male paired housing) interaction. Isolation for 1 d resulted in increased depressive-like symptoms, and 2-d isolation induced elevated anxiety-like behavior in sexually inexperienced rats, while rats with sexual experience exhibited comparable levels of emotionality at each isolation time. Moreover, isolated rats without sexual experience emitted less 22- and 50-kHz USVs, but sexually experienced rats exhibited similar affective states compared with control ones. These results suggested that prior sexual experience could have a modulatory effect on experimental rat emotional responses to isolation.