Cellular Mechanisms by Which Social Status Alters Behavioral Responses to Stress

Understanding the cellular mechanisms that control resistance and vulnerability to stress is an important step toward identifying novel targets for the prevention and treatment of stress-related mental illness. Dominant and subordinate animals have been shown to exhibit different behavioral and physiological responses to stress, with dominants often showing stress resistance and subordinates showing stress vulnerability. We have previously found that dominant hamsters exhibit reduced social avoidance following social defeat stress compared to subordinate hamsters, although the extent to which stress resistance in dominants generalizes to non-social stressors is unknown. In this study dominant, subordinate, and control male Syrian hamsters were exposed to acute restraint stress for 30 minutes. In one cohort of animals, brains were collected for c-Fos immunohistochemistry following restraint stress. In a second cohort, blood samples were collected immediately following restraint and animals were tested for anxiety-like behavior in an open field arena 24 hours later. Preliminary data indicate that restrained animals exhibited increased plasma cortisol compared to non-restrained controls. Also, restraint stress increased the number of c-Fos-positive cells in several brain regions including the infralimbic cortex, prelimbic cortex, medial amygdala, and paraventricular nucleus of the hypothalamus. Analysis of c-Fos immunoreactivity, plasma cortisol, and anxiety-like behavior in dominant and subordinate animals is ongoing. This project will address whether resistance to social defeat stress in dominant hamsters generalizes to restraint stress and extend existing literature on the domain-general vs. domain-specific nature of stress resilience.