Urocortin 2 modulates aspects of social behaviour in mice.

Urocortin 2 (UCN2), a member of the corticotropin-releasing hormone family, is involved in the regulation of stress-related behaviours in rodents. To determine its physiological function we generated mice lacking UCN2 by applying a classical knockout strategy. We examined hypothalamus-pituitary-adrenocortical axis activity, anxiety- and depression-related behaviours without finding significant differences between mutant and wild-type littermates. Investigating social abilities we observed, that male, but not female, UCN2 knockout animals showed an altered social behaviour. Here we report that male UCN2 null mice showed more passive social interactions and reduced aggressiveness in comparison to wild-type animals. In conclusion, UCN2 seems to modulate aggressive behaviour in male mice. Furthermore, our findings provide additional evidence for previously reported sex-specific effects of UCN2.