Social Dominance Alters Stress-Induced Neural Activity and Generates Individual Differences in Stress Vulnerability

Identifying the physiological and behavioral mechanisms that underlie stress vulnerability is a crucial step toward identifying novel targets for the prevention and treatment of stress-related disorders. Social status is a key environmental factor that contributes to individual variations in stress vulnerability. In particular, achieving a subordinate social status has been shown to produce susceptibility to anxiety-like and depressive-like behavior. In this project, our aim was to identify neural ensembles regulating how dominance status modulated stress-induced changes in avoidant behavior in male and female Syrian hamsters. Using a viral vector that codes for robust activity marker (RAM), we investigated whether stress-induced RAM expression in the infralimbic (IL) region of the prefrontal cortex and posteroventral medial amygdala (MePV) accounts for status-dependent variation in stress vulnerability. We found that dominant male and female hamsters showed differences in stress-induced neural activity in the IL and MePV compared to their subordinate counterparts. We found that latency to approach the light zone of a light/dark transition test predicted the acquisition of social dominance for females and this activity was positively associated with greater IL activation. We also showed that time spent in the dark zone of a light/dark transition test predicted the acquisition of a subordinate social status for males and was negatively associated with IL activity. Overall, we found several various experience-dependent changes in anxiety-like behaviors displayed in social avoidance, light/dark transition, and conditioned defeat tests. These findings suggest that social dominance alters stress-induced neural activity in the IL which underlies status-dependent differences in stress vulnerability.