title: Potentiation of luteinizing hormone release by estradiol at the level of the pituitary.
abstract: The objective of this study was to determine the influence of estradiol-17beta and/or progesterone on gonadotropon secretion at the level of the pituitary. Female rats in which the hypothalamo-hypophyseal connections had been permanently interrupted after castration served as the experimental model in which the effect of estradiol and/or progesterone on LH-RH-induced gonadotropin release was examined. In out experimental animals, LH secretion was readily activated by LH-RH administration. LH release was greatly augmented by the prior administration of estradiol benzoate (1 mug/kg b.w./day). Progesterone (5 mg/day) in the absence of estradiol did not modify the 10-min responese to LH-RH but reduced the enhancement of LH secretion caused by estradiol pretreatment. Our findings suggest that estradiol potentiated the releasing effect of LH-RH at the level of the gonadotroph, whereas progesterone interfered with the potentiation effect. Plasma levels of FSH were not significantly elevated above the basal value by the administration of LH-RH alone, or in combination with estradiol and/or progesterone.
mesh_terms: D000818:Animals; D002369:Castration; D004347:Drug Interactions; D004958:Estradiol / Q000494:pharmacology*; D004965:Estrogen Antagonists; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects; D007986:Luteinizing Hormone / Q000378:metabolism*; D010902:Pituitary Gland / Q000378:metabolism*; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D011374:Progesterone / Q000494:pharmacology*; D051381:Rats
chemical_list: D004965:Estrogen Antagonists; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone