title: Social context-dependent relationships between mouse dominance rank and plasma hormone levels.
abstract: The associations between social status and endogenous testosterone and corticosterone have been well-studied across taxa, including rodents. Dominant social status is typically associated with higher levels of circulating testosterone and lower levels of circulating corticosterone but findings are mixed and depend upon numerous contextual factors. Here, we determine that the social environment is a key modulator of these relationships in Mus musculus. In groups of outbred CD-1 mice living in stable dominance hierarchies, we found no evidence of simple linear associations between social rank and corticosterone or testosterone plasma levels. However, in social hierarchies with highly despotic alpha males that socially suppress other group members, testosterone levels in subordinate males were significantly lower than in alpha males. In less despotic hierarchies, where all animals engage in high rates of competitive interactions, subordinate males had significantly elevated testosterone compared to agonistically inhibited subordinates from despotic hierarchies. Subordinate males from highly despotic hierarchies also had elevated levels of corticosterone compared to alpha males. In pair-housed animals, the relationship was the opposite, with alpha males exhibiting elevated levels of corticosterone compared to subordinate males. Notably, subordinate males living in social hierarchies had significantly higher levels of plasma corticosterone than pair-housed subordinate males, suggesting that living in a large group is a more socially stressful experience for less dominant individuals. Our findings demonstrate the importance of considering social context when analyzing physiological data related to social behavior and using ethologically relevant behavioral paradigms to study the complex relationship between hormones and social behavior.
authors.affiliation: Department of Psychology, Columbia University, NY, New York 10027, USA.
authors.forename: Cait M
authors.initials: CM
authors.lastname: Williamson
authors.affiliation: Department of Psychology, Columbia University, NY, New York 10027, USA.
authors.forename: Won
authors.initials: W
authors.lastname: Lee
authors.affiliation: Department of Psychology, Barnard College, NY, New York 10027, USA.
authors.forename: Russell D
authors.initials: RD
authors.lastname: Romeo
authors.affiliation: Department of Psychology, Columbia University, NY, New York 10027, USA; Center for Integrative Animal Behavior, Columbia University, New York 10027, USA. Electronic address: jc3181@columbia.edu.
authors.forename: James P
authors.initials: JP
authors.lastname: Curley
mesh_terms: D000818:Animals; D003345:Corticosterone / Q000097:blood*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D012919:Social Behavior; D012930:Social Dominance; D013223:Statistics as Topic; D013739:Testosterone / Q000097:blood*; D013997:Time Factors
chemical_list: D013739:Testosterone; D003345:Corticosterone