Student Theses and Dissertations

Date of Award

1985

Document Type

Thesis

Degree Name

Doctor of Philosophy (PhD)

Abstract

A pathway connecting the preoptic region and the ventral midbrain regulates the performance of maternal behavior by female rats. There Is also evidence that the facllltatory action of estrogen on maternal behavior Is mediated via estrogen target cells In the medial preoptic region. Neither the anatomical elements that constitute this functional pathway nor the neuroendocrine events triggered by the estrogenic signal have been defined. The first set of studies described In this thesis (Chapter 2) employed a method combining steroid hormone autoradiography and fluorescent dye retrograde tracing to demonstrate that numerous estradlol-concentrating neurons In the medial preoptic region of the rat brain (especially those In the lateral portion of the medial preoptic nucleus. In the medial preoptic area, and In the ventral and caudal bed nucleus of the stria terminal Is) have projections to the ventral tegmental area and the midbrain central grey. These anatomical results are described In detail, and It Is proposed that the facllltatory effect of estrogen on maternal behavior may Involve alterations in function of preoptic estradlol-concentrating neurons that send their axons directly to the midbrain. A second set of experiments investigated the possibility that estrogen's action on maternal behavior may Involve Interactions with brain oxytocin systems. It Is demonstrated (Chapter 3) that 1. raised central levels of oxytocin can Induce short-latency maternal behavior In ovariectomized, estrogen-primed virgin rats 2. that this effect Is estrogen-dependent 3. that the effect Is sensitive to duration of test cage habituation 4. that treatment of 16-day pregnant, ovariectomized and hysterectomized estrogen-primed rats with antisera to oxytocin or an analog antagonist of oxytocin delays the short-latency onset of maternal behavior and 5. that Injection of oxytocin directly Into the ventral tegmental area produces shortlatency maternal behavior similar to that elicited In preceding experiments by Intracerebroventrlcular Injection. The final chapter (Chapter 4) considers the role of the ventral tegmental area In the regulation of maternal behavior.

Comments

A thesis submitted to the Faculty of the Rockefeller University in partial fulfillment of the requirements for the degree of Doctor of Philosophy

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