Influence of the Pattern of Hormone Administration on Behavioral and Biochemical Responses to Estrogens

The pattern of estrogen administration has recently been recognized as an important factor in determining the biological response to the hormone. The experiments carried out in this dissertation have investigated a particular phenomenon by which two pulses of estradiol stimulate female sexual behavior much more effectively than a single pulse of the same total dose of the hormone. The influence of the temporal pattern of estrogen presentation on several aspects of estrogen action related to the stimulation of sexual receptivity was assessed. Ovariectomized female rats were found to be responsive to separate pulses of estradiol given at intervals ranging from 3-48 hours apart, and continued to display lordosis as late as 36 hours after the second estrogen exposure. The increased sensitivity to the pulsatile administration of estradiol may be a general characteristic of estrogen-stimulated responses. Neural progestin receptor levels were increased after separate pulses of estradiol as compared to a single pulse of the same total dose. The dose-response curve for this response was shifted approximately ten-fold by separate pulses. Exposure to estrogen did not alter the affinity or availability of neural cytosol estrogen receptors. Neural estrogen receptor processing was stimulated by both single and separate pulses of estradiol, however the extent of processing varied depending on the pattern of estrogen administration. Estrogen receptor processing in the medialbasal hypothalamus appeared to be more extensive after separate pulses than after a single injection. Finally, use of the experimental paradigm of administering estradiol pulses, rather than continuous exposure to the hormone, has led to the discovery of several neurochemical events which accompany the administration of estradiol. Experiments using anesthetics or alpha(,1)-noradrenergic blockers indicated that neural activity in the hypothalamus and/or noradrenergic input may be required during estrogen priming for the subsequent display of lordosis.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Psychology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Clark, Ann Stephanie

• Psychology, Physiological

Identifier

(UMI)AAI8521746

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/69656