Date of Award

1-1-2010

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Psychology

Program

Behavioral Neuroscience

Content Description

1 online resource (v, 92 pages) : illustrations (some color)

Dissertation/Thesis Chair

Christine K Wagner

Committee Members

Robert Rosellini, Bruce Svare

Keywords

estrogen receptor, hypothalamus, lordosis, progesterone receptor, sex difference, ventromedial nucleus, Progesterone, Hypothalamic hormones, Steroid hormones, Rats, Brain

Subject Categories

Biological Psychology

Abstract

Steroid induced gene transcription plays an important role in neural sex differences within many mammalian species. Steroid hormones actions within the developing brain have profound, permanent effects in the development of neurochemical processes and behaviors. Within the developing ventromedial nucleus of the hypothalamus (VMN), a potent transcription factor, the progesterone receptor (PR), is highly expressed within female rats. Furthermore, the regulation of PR within the developing VMN of the female rat is anatomically and developmentally specific. Typically, PR expression is highly dependent on the activity of estradiol acting at ERα. As such, circulating levels of estradiol act to induce PR within various brain regions that express estrogen receptors (ER), including the adult female VMN and the VMN of the male. However, in the postnatal female VMN, the regulation of PR seems to be independent of ERα activity such that PR is expressed in the relative absence of estradiol. In stark contrast, within the medial preoptic area of the same animals, PR is highly dependent on ER activity, suggesting that PR may be tightly regulated within the VMN of the neonatal female. These observations are intriguing as the VMN is critically important to female sexual behaviors and the possibility exists that PR is highly regulated in the developing VMN to facilitate the proper development of this vital brain area. Thus, this thesis tested the hypothesis that PR plays a role in the development of the VMN and female sexual behaviors inadulthood. Results demonstrate that blocking the actions of ER did not alter PR expression in the VMN, but significantly decreased PR in the MPN, suggesting that PR is regulated in the female VMN by an unknown factor. Chapters III and IV tested a possible role of PR in neural development, testing the hypothesis that PR can mediate a portent neurotrophic factor as well as female sexual behavior in adulthood. Results demonstrate that PR does not, play a role in these two behaviors and further studies are needed to find a functional role of PR within the development of the VMN.

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