Differential effects of oxytocin receptor antagonist on social rank and other social behavior in mice

Social rank within a group is essential for survival in many animals. Rank in the community helps to avoid unnecessary conflicts and establish stable relationships with others. Recently, oxytocin has received increasing attention for its function in social behavior. However, the causal relationship between oxytocin levels and social rank has remained unclear. Here, we examined the effects of intraperitoneal injection of the oxytocin receptor antagonist L-368-899 on (1) social rank, (2) sex preference, and (3) dyadic interaction in male mice. In the tube test, injection of the oxytocin receptor antagonist had no effect on first-place mice, but caused rank fluctuation of the social rank in second-place mice, suggesting that the function of oxytocin in the maintenance of the social rank is rank-dependent. Second, injection of the oxytocin receptor antagonist dose-dependently impaired the sex preference of the male mice, confirming that oxytocin is essential in sexual behavior. Third, injection of the oxytocin receptor antagonist had no effect on the dyadic interaction between the male mice, suggesting that oxytocin is not necessary in direct social interaction. Taken together, these results demonstrate that the role of the oxytocin in male mice is limited to a specific context of social behavior. Highlights The stable social rank of the male mice in their cages was clearly observed in the tube test. Administration of an oxytocin receptor antagonist to first-place mice caused no change in social rank. Administration of an oxytocin receptor antagonist to second-place mice caused changes in social rank in some groups. Sex preference, but not social and dyadic interactions, were impaired after the injection of the oxytocin receptor antagonist.