Date of Award


Degree Name

Doctor of Philosophy



First Advisor

Dr. Lisa E. Baker

Second Advisor

Dr. Alan D. Poling

Third Advisor

Dr. Cynthia J. Pietras

Fourth Advisor

Dr. Kathryn M. Potoczak


Models of depression, social separation, anhedonia, forced swim test


Animal models of depression have existed for decades, yet one that completely satisfies research objectives remains elusive. One proposed model is a social separation model of depression using mice, which involves group housing subsequently followed by separation and placement into individual housing. the present study investigated the proposed separation model using rats and two common tests of depressive-like behaviors, the forced swim test (FST) and the sucrose consumption test (SC). The current study also examined activity in an enriched environment (EEA) to determine its potential as a novel test of depression. Forty-six male and 43 female Sprague-Dawley weanlings were separated by sex and place in either single (IS) or paired housing (PD). Subjects were tested on EEA, FST, and SC. Half of the PD rats were then separated (SP) for two weeks. following separation, subjects in all conditions repeated testing on EEEA, FST, and SC. An overall main effect of housing condition on the FST was found, with IS subjects showing the highest immobility scores, SP having the next highest and PD having the lowest scores. however, significant differences between specific conditions were not found with post hoc tests. No effects of housing condition were found for EEA or SC. Sex effects were found for these measures, with females showing higher levels of activity and higher levels of sucrose consumption than males. These findings do not eliminate the potential of social separation as a model of depression in rats, but rather suggest alternative modifications to the model may be necessary. Suggestions for future investigations of this model, as well as implications of the sex differences found in the EEA and SC tests are discussed.


This dissertation is unavailable because permission has not been granted by the author. A print copy is available at the WMU Waldo Library in the General Stacks at call number: RC 9999.2.W387

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