Atp1a3‐ deficient heterozygous mice show lower rank in the hierarchy and altered social behavior

Atp1a3 is the Na‐pump alpha3 subunit gene expressed mainly in neurons of the brain. Atp1a3 ‐deficient heterozygous mice ( Atp1a3 +/− ) show altered neurotransmission and deficits of motor function after stress loading. To understand the function of Atp1a3 in a social hierarchy, we evaluated social behaviors (social interaction, aggression, social approach and social dominance) of Atp1a3 +/− and compared the rank and hierarchy structure between Atp1a3 +/− and wild‐type mice within a housing cage using the round‐robin tube test and barbering observations. Formation of a hierarchy decreases social conflict and promote social stability within the group. The hierarchical rank is a reflection of social dominance within a cage, which is heritable and can be regulated by specific genes in mice. Here we report: (1) The degree of social interaction but not aggression was lower in Atp1a3 +/− than wild‐type mice, and Atp1a3 +/− approached Atp1a3 +/− mice more frequently than wild type. (2) The frequency of barbering was lower in the Atp1a3 +/− group than in the wild‐type group, while no difference was observed in the mixed‐genotype housing condition. (3) Hierarchy formation was not different between Atp1a3 +/− and wild type. (4) Atp1a3 +/− showed a lower rank in the mixed‐genotype housing condition than that in the wild type, indicating that Atp1a3 regulates social dominance. In sum, Atp1a3 +/− showed unique social behavior characteristics of lower social interaction and preference to approach the same genotype mice and a lower ranking in the hierarchy.