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KMID : 0381219930250010001
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Journal of RIMSK
1993 Volume.25 No. 1 p.1 ~ p.17
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Direct Effect of Gonadotropin Releasing Hormone and Its Agonistic Analogs on Ovarian Functions
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Abstract
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Native GnRH is a hypothalamic decapeptide, which stimulates the release of pituitary gonadotrpins, while, GnRH agonist is produced from the structural modification of native GnRH molecules, which has increased biologic activity and longer
half-life
compared to native GnRH.
Continuous administration of GnRH or its agonistic analogs results in the paradoxical suppresion of gonadal function rather than stimulation.
By these hormonal effects, GnRH-agonist are widely used at present for the various clinical conditions in which suppresion of gonadal function is benificial, such as prostatic cancer and hyperphasia in men, and breast cancer precocious puberty,
endometriosis, leiomyoma and so on in women.
This effect is mostly explained by desensitization of gonadotropes of pituitary gland. But other 2 possible mechanisms, the is, LH-induced desensitization of gonadal cells and direct effect of GnRH and GnRH-agonist on gonadal cells can be
proposed
to
explain this effect.
This paper is presented to investigate the direct extrapituitary effect of GnRH and its agonist on ovarian functions, especially ovarian steroidogenesis
Survey of recent literatures concludes that human ovaries, especially granulosa cells of preovulatory follicles have specific high-affinity GnRH receptors, like rat ovaries. But direct effects of GnRH and its agonist on human ovarian functions
have
been
controversial in vivo and in vitro.
Presence of GnRH receptors on ovarian cell also suggests the production of GnRH or GnRH like peptides form human ovaries, and possible paracrine or autocrine actions of these locally produced petides in the ovary.
But definite condlusion about direct control of ovarian function by hypothalamic GnRH or locally produced GnRH-like peptide await resolution at present.
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KEYWORD
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