Postweaning Isolation Rearing Alters the Adult Social, Sexual Preference and Mating Behaviors of Male CD-1 Mice.

No study has comprehensively evaluated the effect of postweaning isolation on the social and sexual behaviors of a certain strain of rodents in ethology. The present study aims to explore how and to what extent isolation rearing after postweaning affects the social and sexual behaviors of male CD-1 mice in adulthood systematically. Male CD-1 mice were randomly assigned to two groups: isolation reared (IS, one mouse per cage, = 30) and group housed (GH, five mice per cage, = 15). The mice underwent isolation rearing from postnatal day 23 to day 93. Then, social affiliation, recognition and memory were measured through selection task experiments. Social interaction under a home cage and novel environment were measured via resident-intruder and social interaction test, respectively. Furthermore, sexual preference, homosexual and heterosexual behaviors were measured. Our study found that postweaning isolation increased the social affiliation for conspecifics ( = 0.001), reduced social recognition ( = 0.042) and impaired social memory. As for social interaction, isolated mice showed a remarkably increased aggression toward the intruder male in a home cage or novelty environment. For instance, isolated mice presented a short attack latency ( < 0.001), high attack frequency ( < 0.001) and long attack duration ( < 0.001). In addition, isolated mice exhibited further social avoidance. Contrastingly, isolated mice displayed a reduced sexual preference for female (IS: 61.47 ± 13.80%, GH: 70.33 ± 10.06%, = 0.038). As for heterosexual behavior, isolated mice have a short mating duration ( = 0.002), long mounting latency ( = 0.002), and long intromission latency ( = 0.015). However, no association was observed between postweaning isolation and homosexual behavior in male CD-1 mouse. Postweaning isolation increased the social affiliation, impaired the social cognition and considerably increased the aggression in social interaction of adult male CD-1 mice. Postweaning isolation induced a decreased sexual preference for female in adulthood. Postweaning isolation extended the latency to mate, thereby reducing mating behavior. No association was observed between isolation and homosexual behavior.