Date of Award

8-7-2018

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Neuroscience Institute

First Advisor

Dr. Laura L. Carruth

Second Advisor

Dr. H. Elliott Albers

Third Advisor

Dr. Erin Tone

Fourth Advisor

Dr. Walter Wilczynski

Abstract

The detrimental effects of early life stress on brain development and behavior in adulthood are well known, but the effects of acute stressors experienced later in life on brain activation and adult behaviors, such as mate preference, are less understood. It is generally thought that acute stress, unlike chronic stress, leads to adaptive responses like encouraging reproduction over survival. The reverse, promoting survival over reproduction, occurs under chronic stress conditions. Physiological responses to stress are mediated by glucocorticoids receptors (GRs) and DNA methylation has been proposed as a mechanism by which stress, at any point in life, can lead to adaptive and maladaptive changes in the brain and in behavior. Corticosterone, a glucocorticoid steroid hormone, is thought to mediate variation in female partner preference when environmental conditions are not ideal. Female zebra finches choose their mates based in part on male song and it is unknown if female perception of song or preference for her mate is altered by stress.

We examined the effects of an ecologically relevant stressor (cold exposure) and a physiological stressor (oral corticosterone administration) experienced early in life to determine if they differentially alter HPA axis sensitivity and global DNA methylation in the brains of juvenile and adult zebra finches. We showed that both stressors resulted in blunting of the stress response in juveniles and adults, and in hypomethylation of the brains of juveniles only.

We investigated whether exposure to an acute stressor in adulthood alters female preference for their mate or for mate’s song. We found that acute stress decreased the strength of a female’s preference for her mate and her mate’s song. We also examined whether exposure to an acute stressor would alter a female’s typical pattern of neuronal activation, using an antibody to the immediate early gene ZENK, in auditory brain regions that might be involved in perceptual song processing. In addition, we investigated whether acute stress would increase GR quantity in auditory brain regions that might be involved in perceptual song processing. We demonstrated that acute stress decreased neuronal activation and increased GR immunoreactivity in all brain regions.

Available for download on Friday, July 10, 2020

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