Date of Award

Spring 2013

Project Type

Dissertation

Program or Major

Psychology

Degree Name

Doctor of Philosophy

First Advisor

Robert Drugan

Abstract

Millions of Americans are suffering from depression each year, leading to a significant number of individuals who seek treatment for their ailment. However, fewer than 50 percent of depressed individuals fully recover using current methods. The comorbidity between depression and anxiety could be a contributing factor in the lower rates of recovery. The demonstrated correlation between anxiety and depression has led to the term "anxious depression," which is associated with difficulty in coping, a poorer rate of recovery, and more severe symptoms of depression. The purpose of this dissertation was to expand on an existing animal model of depression (intermittent swim stress) and its possible relationship to anxiety. In the intermittent swim stress (ISS) model, animals experienced 100, 5 second trials of cold water swim stress, and subsequent behavioral and cellular mechanisms were assessed. Behavioral measures incorporated animal models of anxiety (i.e., open field test and juvenile social exploration), while serotonergic and noradrenergic neurons were assessed at the dorsal raphe nucleus and locus coeruleus, respectively, through immunohistochemistry techniques. Results indicated ISS-induced deficits were noted for social exploration, but not with the open field test. No apparent cellular differences were revealed following the open field test, but this has yet to be investigated for juvenile social exploration. The anxiety effects produced by ISS support the trans-situational value of the model and also suggest ISS as a possible animal model of post-traumatic stress disorder. Future directions should assess cellular mechanisms following exposure to juvenile social exploration as well as explore the time course of the neural activity marker described in the experiments.

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