Document Type


Date of Award


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Terrence Deak


There is a growing body of evidence supporting the association between inflammation and major depressive disorder (MDD). One plausible mechanism for this association is sensitization of the immune response, possibly due to prior exposure to stressors. To investigate the validity of this hypothesis, a series of three complimentary cross-species studies was conducted. Study 1 examined the associations between circulating levels of inflammatory markers and in vitro immune reactivity with women’s history of recurrent MDD (rMDD) and their current symptoms of anhedonia. The potential moderating role of women’s history of childhood abuse was also examined. Study 2 and 3 focused on animal models of the influence of adolescent stress on LPS-induced changes in adult anhedonic behavior (Study 2) and inflammatory gene expression in brain areas associated with reward processing and stress (Study 3). Although there was no evidence of increased circulating or stimulated levels of inflammation among women’s history of rMDD in Study 1, current level of anhedonia was associated with increased stimulated levels of inflammatory markers. Results of Study 2 showed a marginally significant trend for the effect of adolescent stress exposure on anhedonia-like behavior in adult rats, such that rats subjected to an acute stressor in adolescence showed a decreased preference for palatable substance (sucrose) as adults. Finally, the results of Study 3 provided no support for altered neuroinflammatory response in the brain areas related to reward processing and stress based on the adolescent stress exposure. Overall, the findings highlight the importance for integration of interdisciplinary methodology in psychological studies, yield initial support for the role of the immune system in anhedonia and provide important directions for future research.

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