Publication Date

2016

Document Type

Dissertation/Thesis

First Advisor

Grippo, Angela J.

Degree Name

Ph.D. (Doctor of Philosophy)

Legacy Department

Department of Psychology

LCSH

Stress (Physiology); Stress (Psychology); Prairie vole--Effect of stress on

Abstract

The experience of stress can have profoundly negative effects on overall psychological and physiological health. It is also true that in social species, interactions with others can have the power to either ameliorate or potentiate these effects. As both stress levels and social interconnectedness rise within our world, it becomes imperative for science to better understand the interactions between stress and the social environment. In support of this goal, the purpose of the current study was to investigate whether a prior established bond between two social animals enhances the physiological and behavioral response to stress in a bonded partner that does not directly experience a stressor, but rather observes another animal directly experience the stressor in an extremely social species, the prairie vole (Microtus ochrogaster ). The current study also examined a possible neural mechanism that could mediate the vicarious stress response and allow for such a vicarious stress enhancement to occur. The focus of this investigation is the nonapeptide arginine vasopressin (AVP), which is one of several chemicals that are released when an organism experiences stress. This chemical helps an organism cope with a stressor assisting in the ultimate increase in heart rate, blood pressure, and the amount of energy available in the blood. These functions occur through stimulation of numerous subtypes of AVP receptors that are located throughout the body, performing various functions depending on the type and location of the receptor. Interestingly, this chemical has also been shown to play a vital role in other social and cognitive functions, such as enhancing bonding ability, and increasing social recognition and memory. It was hypothesized that AVP is released in organisms when they experience a stressor, even when the organism in question experiences the stressor indirectly, or vicariously, through observing another organism directly experience a stressor, and that if a prior bond exists between the two animals in question, the stress response in an observer animal will be elevated when compared to animals that are unknown to each other. Furthermore, we hypothesized that this enhancement of vicarious stress occurs because AVP that is released during the vicarious experience of stress inadvertently stimulates the AVP receptors in the brain that are responsible for "reminding" the observer animal about the prior established bond between the observer and the target. Therefore, when a prior bond exists between the two animals, the stress response of the observer is elevated due to the increased salience of the event, creating a positive feedback loop, ultimately resulting in a net increase in physiological arousal in the observer. Results of the current study failed to support either of these hypotheses however, with no statistically significant differences in any of the key dependent measures of stress response activation observed. However, secondary analyses provided evidence for no habituation and even a slight sensitization to the testing apparatus during the acclimation period of the experiment in this species, which is in stark contrast to other species of rodent. Because no habituation to the testing apparatus occurred, actual differences in stress response activation may have been obscured in the "noise" of novel stimulus stress. This information provides a framework for the future development of testing paradigms to address this issue, resulting in the ability to draw stronger conclusions. A better understanding of vicarious stress and possible mediating mechanisms might help to explain and prevent the spread of stress in dyadic relationships, as well as within other social groups. Extension of the current research will also provide a possible explanation (through individual variation of the specific AVP receptor studied) that may help to elucidate why some people are more susceptible to the negative effects of vicarious stress than others, and provide a possible pharmacological target that could be utilized to protect the stress experienced by one member of a dyadic relationship (i.e. depression, work stress) from harming those closest to them.

Comments

Advisors: Angela J. Grippo.||Committee members: Mitrick Johns; Leslie Matuszewich; Alan Rosenbaum; Brad Sagarin; Lin Shi; Douglas Wallace.||Includes bibliographical references.||Includes illustrations.

Extent

xii, 217 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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