Social status influences normal and pathological behaviors in mice, a role for dopamine and stress signaling

The rules leading to the emergence of a social organization and the role of social ranking on normal and pathological behaviors remain elusive. Here we show that groups of four genetically identical male mice rapidly form enduring social ranking determined by precedence test and the sharing of beneficial resources. Highest ranked individuals are more anxious, more social and display increased spatial working memory. Whereas differences in anxiety between individuals appear after rank attainment, the higher sociability of top-ranked mice preexist. These behavioral differences correlate with physiological change. The highest ranked mice display indeed lower bursting activity of VTA dopamine neurons. The same animals are less responsive to preclinical models of stress behavioral disorders involving changes of dopamine system. They display lower locomotor sensitization to cocaine and are more resilient to repeated social defeat. The ablation of stress-elicited glucocorticoid receptor gene in dopaminoceptive neurons that affects the same pathological models, upwards the ranking status of mutant individuals. Altogether, these results support a role for social ranking in patterning interindividual VTA dopaminergic activity, behavioral responses and susceptibility to stress-related psychopathologies.