A novel odor-mediated social exclusion model reveals behavioral effects distinct from social isolation in mice

Social exclusion, such as ostracism or being ignored within a group, causes severe psychological distress known as social pain. However, commonly used animal models of social stress, including social isolation and social defeat stress, do not fully reproduce the specific social context in which an individual is avoided while remaining within a social group. In the present study, we established a novel odor-mediated social exclusion paradigm and compared its behavioral and physical phenotypes with those produced by social isolation.

Mice were assigned to one of three experimental conditions: group-housed control, social exclusion, or social isolation. In the social exclusion condition, one mouse in each group-housed cage was topically treated with a depilatory cream to induce avoidance by cage mates. After 7 days of exposure, physical characteristics and behavioral responses were evaluated using a battery of behavioral tests.

Mice in the social exclusion group showed reduced body weight gain and decreased grip strength compared with control mice, whereas these changes were not evident in socially isolated mice. In behavioral tests, both stress groups exhibited reduced time spent in the center area of the open field. Notably, the two groups showed distinct locomotor patterns: mice subjected to social exclusion displayed reduced locomotor activity in the light/dark transition and open field tests, whereas socially isolated mice exhibited increased locomotion in the elevated plus maze test.

These findings indicate that odor-mediated social exclusion produces behavioral and physical phenotypes distinct from those induced by social isolation, primarily characterized by alterations in locomotor and exploratory behavior. This paradigm provides a useful experimental model for investigating the consequences of non-aggressive intragroup social stress, and may serve as a foundation for future studies examining its neurobiological and affective dimensions.