The studies described in this dissertation were designed to examine certain aspects of the neuronal networks controlling sexual receptivity facilitated by estradiol and progesterone in female guinea pigs. In particular, the first part of this thesis was designed to localize discrete sites within the mediobasal hypothalamus (MBH) where local activation by estradiol is sufficient to induce responsiveness to progesterone-facilitated sexual receptivity. Implants localized within the rostroventral ventrolateral hypothalamus (rostro-ventral VLH) were sufficient to induce responsiveness to progesterone. Using immunocytochemistry for progestin receptors, the same implants were found to induce progestin receptors within the same area. The second part of this thesis was focussed on the description of afferent connections to the rostro-ventral VLH, and the identification of some of these afferents as originating from estradiol-sensitive neurons. Using retrograde tracing techniques, afferents to the rostro-ventral VLH were observed throughout the forebrain and the midbrain, particularly within the medial preoptic nucleus, bed nucleus of the stria terminalis, anterior hypothalamus, amygdala, and lateral parabrachial nucleus. Using immunoreactivity to label neurons containing estrogen receptors, retrogradely labelled neurons were found is most areas highlighted by immunolabelling. Furthermore, within some areas, particularly within the medial preoptic nucleus, medial amygdala, and bed nucleus of the stria terminalis, retrogradely labelled neurons were also immunoreactive to estrogen receptors. The third part of this thesis was designed to study connections between estrogen receptor-rich hypothalamic areas. Interestingly, the results show that neurons within the estrogen receptor-poor ventromedial nucleus were connected to estrogen receptor-immunoreactive neurons in estrogen receptor-rich areas such as the rostro-ventral VLH, suggesting that this nucleus integrates estrogen-dependent hypothalamic functions. In conclusion, the present results point to a discrete part of the hypothalamus as a site of action for estradiol and progesterone in the facilitation of sexual receptivity. Furthermore, this area is connected to a network of estrogen-sensitive neurons integrating several sensory functions involved in the behavior. Finally, this estrogen-dependent function might be integrated with other estrogen-dependent functions at the level of the hypothalamus.
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:dissertations-8371 |
| Date | 01 January 1992 |
| Creators | Delville, Yvon |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Language | English |
| Detected Language | English |
| Type | text |
| Source | Doctoral Dissertations Available from Proquest |
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