Publication Date


Document Type


First Advisor

Grippo, Angela J.

Second Advisor

Matuszewich, Leslie

Degree Name

M.A. (Master of Arts)

Legacy Department

Department of Psychology


Chronic and acute stressors are implicated in mental illnesses such as depression, anxiety and posttraumatic disorder. These adulthood disorders may be influenced by stressor exposure during early life. However, controlled mild stressors are linked to the building of resiliency towards later intense stressors. Previously, rodent models have been used to investigate the resilience-promoting effects of early life stress inoculation protocols. For example, the presentation of mild stressors (such as an experimenter handling a rodent for brief periods of time) or exposure to environmental enrichment (such as a presenting a variety of items and activities in the home cage of a rodent) served as resilience builders, showing decreased negative outcomes both in behavioral and biological measures. However, these potential stress inoculation protocols have not been compared. The purpose of the proposed experiment was to test the potential difference in depressive and anxiety-like behaviors following exposure to either environmental enrichment or brief handling “stress” by an experimenter in a rodent model. This was accomplished by introducing female and male prairie voles to either environmental enrichment continuously or 10 seconds of cup handling daily for seven days or leaving animals unmanipulated during the early life period. After this period, the animals were exposed to a four-week social isolation period. Following social isolation, animals underwent behavioral tests of affective behaviors as validated dependent measures of the stress response. The present study hypothesized that handling would provide a greater reduction in the stress response following social isolation in comparison to both unmanipulated controls and environmentally enriched animals. The results revealed that environmental enrichment exposed group showed both decreased anxiety-like behavior, decreased depressive-like behavior, and increased depressive-like behavior with sex differences. Additionally, handling exposed animals exhibited increased anxiety-like behavior, decreased anxiety-like behavior, and decreased depressive-like behavior. The results demonstrated that environmental enrichment provided greater reduction in anxiety and depressive-like behaviors compared to handling. Opposite of initial predictions, early life handling did not foster resiliency and perhaps added to the negative consequences of social stress, as seen in the increase in anxiety and depressive-like behaviors. This research provided greater insight on the effectiveness of early life resiliency treatments as forms of protection against adulthood social stress. Further, the findings may better inform the appropriate timing of interventions to attenuate the probability of severe psychopathology development.


153 pages




Northern Illinois University

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