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KMID : 0360419940300010019
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Korean Journal of Pharmacology
1994 Volume.30 No. 1 p.19 ~ p.28
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Regulation of Luteinizing Hormone Release and Subunit mRNA by GnRH and Ovarian Steroids in Cultured Anterior Pituitary Cells
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Kim Chang-Mee
Park Il-Sun
Ryu Kyung-Ja
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Abstract
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The effects of gonadoropin-releasing hormone (GnRH) and ovarian steroid hormones on the release of luteinizing hormone (LH) and its subunit mRNA levels were investigated in anterior pituitary cells in culture. LH concentration was measured by a specific radioimmunoassay and mRNA levels of u and subunits by RNA slot blot hybridization assay. GnRH stimulated LH release in a dose-dependent manner from cultured pituitary cells. However, the basal LH release in the absence of GnRH was not changed during the course of 24h culture, strongly suggesting that release of LH is directly controlled by GnRH. The treatment of the pituitary cells with GnRH increased subunit mRNA levels in a dose-dependent manner, reaching the maximum with GnRH while no significant increase in subunit mRNA levels was observed after GnRH treatment. Estradiol did not augment GnRH-induced LH release while progesterone augmented GnRH-induced LH release in a dose-dependent manner at the level of pituitary. However, estradiol and progesterone increased basal and GnRH-induced subunit mRNA levels in a dose-dependent manner. The treatment of estrogen antagonist, LYI17018 blocked the effect of estradiol on GnRH-induced subunit mRNA levels in a dose-dependent manner while progesterone antagonist, Ru486 tended to block the effect of progesterone on GnRH-induced subunit mRNA levels. It is therefore suggested that GnRH Playa a major role in LH release and subunit biosynthesis by influencing the steady state subunit mRNA loves and ovarian steroid hormones modulate subunit biosynthesis via directly acting on pituitary gonadotropes.
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KEYWORD
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subunit, GnRH, Estrogen, Progesterone, Pituitary primary cell culture
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