The regulation of pituitary gonadotropin release by testicular steroids is well established and is part of the dynamic equilibrium maintained in the hypothalamo-hypophyseal-gonadal axis. A nonsteroidal testicular factor, GnS, may also contribute to the negative feedback regulation of FSH synthesis and release. The physiological role of this factor is the subject of these studies. / Since FSH contributes to normal spermatogenesis in the adult male rat, long-term suppression of serum FSH would diminish, at least quantitatively, normal spermatogenesis. Chronic administration of GnS in the form of porcine follicular fluid (pFF), significantly depresses serum FSH levels, but it also induces antibodies to the FSH-inhibiting activity. Thus, FSH suppression cannot be maintained long enough to effect changes in fertility. / Constant low levels of testosterone produced by Silastic capsules provide complete feedback control of FSH in the acute castrate. Testosterone prevents the postcastration increase in serum FSH which, in turn, prevents the early postcastration drop in pituitary FSH. Later postcastration elevations in pituitary FSH are also prevented. Although GnS suppresses serum and pituitary FSH by inhibiting release and synthesis, it is not needed in the acute castrate. / In the long-term castrate animal, testosterone alone only partially controls serum FSH while pituitary FSH levels are increased. GnS prevents the testosterone-induced accumulation of hypophyseal FSH and independently suppresses serum FSH. Thus, in the long-term castrate both testosterone and pFF are needed to suppress FSH levels. / Finally, evidence is presented that constant low levels of androgen, when administered via Silastic capsules, provide more effective feedback than the feedback provided by normal fluctuating androgen levels in the intact rat. / Source: Dissertation Abstracts International, Volume: 44-02, Section: B, page: 0423. / Thesis (Ph.D.)--The Florida State University, 1983.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_75057 |
| Contributors | MCRAE, CAROLYN JEAN., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 200 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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