The control of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) secretion by a hypothalamic releasing peptide (GnRH) and the modulation of FSH and LH secretion by ovarian steroids has been demonstrated. There is increasing evidence that another ovarian factor, gonadostatin (GnS) may also contribute significantly to the control of gonadotropin (FSH and LH) secretion. GnS appears to contribute to the negative feedback on gonadotropin secretion, particularly FSH. The function of a separate factor in the negative feedback control of FSH may be to control, ultimately the number of follicles that develop and ovulate. / Examination of ovarian steroid feedback at physiological concentrations, demonstrated that steroids alone do not provide complete feedback control of FSH secretion. GnS is thought to be the additional factor that completes the negative feedback control of FSH release. Administration of GnS in the form of porcine follicular fluid (pFF) together with physiological levels of estradiol resulted in basal levels of serum FSH. / Steroids exert positive as well as negative feedback control of gonadotropin secretion. Basal and surge release of LH could be fully controlled with estradiol and progesterone alone (replaced to mimic normal changing levels). In contrast, neither basal nor surge secretion of FSH were controlled with steroids. The addition of GnS to a cyclic steroid regimen provided complete control of FSH secretion (both basal and surge) and suggests that GnS may play a significant role in the control of FSH secretion throughout the estrous cycle. / The response of dispersed pituitary cells to estradiol (with or without GnRH) is an enhancement of gonadotropin secretion, in contrast to suppression of gonadotropin secretion seen in vivo. The use of a perfused pituitary cell system allowed the cells to be pulsed with GnRH thereby producing the conditions thought to occur in vivo. Under conditions of pulsed GnRH stimulation the secretion of gonadotropins was dramatically suppressed by gonadostatin and to a small extent by estradiol. / These studies have suggested that gonadostatin may play a significant role in the negative feedback of FSH and to a lesser extent LH secretion. / Source: Dissertation Abstracts International, Volume: 42-12, Section: B, page: 4701. / Thesis (Ph.D.)--The Florida State University, 1982.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_74723 |
| Contributors | WILLIAMS, AARON TRENT., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 184 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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