The ovarian steroids, progesterone and estradiol, regulate luteinizing hormone synthesis and secretion during the estrous cycle of mature ewes. During the luteal phase of the cycle the ovarian steroids inhibit luteinizing hormone secretion. Luteinizing hormone is secreted from the pituitary when stimulated by the hypothalamic neuropeptide, gonadotropin-releasing hormone. Ovarian steroids can inhibit luteinizing hormone secretion indirectly, by decreasing the secretion of gonadotropin-releasing hormone or directly, by modulating the response of the pituitary to gonadotropin-releasing hormone. These studies have examined the direct control of pituitary luteinizing hormone secretion by using an in vivo model in which endogenous gonadotropin-releasing hormone (GnRH) release has been ablated and replaced with exogenous GnRH release at a constant frequency. Progesterone directly inhibited pituitary LH secretion in an estradiol-dependent manner and this may not require inhibition of pituitary LH synthesis. Progesterone inhibition of pituitary luteinizing hormone secretion is associated with enhanced progesterone binding by the pituitary.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/185816 |
| Date | January 1992 |
| Creators | Girmus, Ronald Leslie |
| Contributors | Wise, Mark E., Allen, Ronald E., Komm, Barry S., Guerriero, Vincent, Hoyer, Patricia B. |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | text, Dissertation-Reproduction (electronic) |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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