Estradiol processing by pituitary cells in culture: an examination of the influences of various exposures to progesterone.
Dispersed, estradiol (E2)-treated pituitary cells were used to examine the cellular mechanisms underlying progesterone (P) suppression of GnRH-stimulated LH and FSH secretion. When cells were exposed to 10(-9) M E2 for 48 h prior to GnRH challenge, P (10(-7) M) treatment for the last 24 h suppressed gonadotroph responsiveness to GnRH for both LH and FSH secretion (gonadotropin released/intracellular stores of gonadotropin available for release). To determine if P acts by blocking E2 processing and/or uptake, we exposed cells to 2,4,6,7-3H-E2 +/- P and monitored the level and distribution of 3H-estrogens bound to estrogen receptors salt-extracted from nuclear pellets purified by sucrose density centrifugation. At 1, 4 and 24 h, P had no effect on the level of 3H-estrogen+receptor complexes or on the distribution of receptor-bound 3H-E2, 3H-estrone and 3H-estriol. The results indicate that chronic influences of P to suppress the responsiveness of E2-treated gonadotrophs to GnRH cannot be explained by alterations in estrogen receptor occupation as is the case in reproductive tract tissues.
Krey
L C
LC
Laboratory of Neuroendocrinology, Rockefeller University, New York, New York 10021.
Kamel
F
F
D000818:Animals; D002478:Cells, Cultured; D004958:Estradiol / Q000378:metabolism*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000502:physiology; D007986:Luteinizing Hormone / Q000378:metabolism; D010903:Pituitary Gland, Anterior / Q000187:drug effects* / Q000378:metabolism; D011374:Progesterone / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011960:Receptors, Estrogen / Q000378:metabolism; D013997:Time Factors; D014316:Tritium
D011960:Receptors, Estrogen; D014316:Tritium; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone