title: Actions of 17 beta-estradiol on gonadotropin release induced by drugs that activate intracellular signal transduction mechanisms in rat anterior pituitary cells.
abstract: We studied the effects of 17 beta-estradiol (E2) on luteinizing hormone (LH) and follicle-stimulating hormone (FSH) release induced by drugs that activate different intracellular signal transduction mechanisms in rat anterior pituitary cells. Cells were pretreated with E2 (6 x 10(-10) M) or diluent for 24 h. Then, both E2- and diluent-pretreated cells were incubated for 4 h with E2 or diluent, respectively, with or without drugs, and in the presence or absence of gonadotropin-releasing hormone (GnRH). Media were assayed for LH and FSH by radioimmunoassays. E2 treatment had no effect on basal FSH release, but occasionally stimulated basal LH release. Phospholipase C (PLC), L-alpha-1,2-dioctanoyl glycerol (C8), veratridine, 8-bromo-cyclic adenosine 3',5'-monophosphate (8-Br-cAMP), melittin (a phospholipase A2 [PLA2] activator), arachidonic acid, PLA2, and GnRH all stimulated LH and FSH release in both E2- and diluent-treated cells. E2 treatment increased both LH and FSH release induced by GnRH, PLC, C8, veratridine, and 8-Br-cAMP, but not by melittin, arachidonic acid, and PLA2. Neither C8, PLA2, nor arachidonic acid in combination with a maximal dose of GnRH had additive effects on either LH or FSH release, whereas melittin increased the maximal response to GnRH in both E2- and diluent-treated cells. The effects of veratridine and 8-Br-cAMP depended on dose of GnRH and presence or absence of E2. These results suggest that E2 augments stimulus-coupled gonadotropin release by interacting with the Ca2+-, and/or diacylglycerol-, and cAMP-activated pathways, but not with the arachidonic acid-activated pathway.
authors.affiliation: Department of Veterinary Biosciences, University of Illinois, Urbana 61801.
authors.forename: T C
authors.initials: TC
authors.lastname: Liu
authors.forename: G L
authors.initials: GL
authors.lastname: Jackson
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D004075:Diglycerides / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D006065:Gonadotropins, Pituitary / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000378:metabolism; D008555:Melitten / Q000494:pharmacology; D010741:Phospholipases A / Q000494:pharmacology; D054467:Phospholipases A2; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D010906:Pituitary Hormone-Releasing Hormones / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D015398:Signal Transduction / Q000187:drug effects*; D010738:Type C Phospholipases / Q000494:pharmacology; D014701:Veratridine / Q000494:pharmacology
chemical_list: D004075:Diglycerides; D006065:Gonadotropins, Pituitary; D010906:Pituitary Hormone-Releasing Hormones; C044295:1,2-dioctanoylglycerol; D008555:Melitten; D015124:8-Bromo Cyclic Adenosine Monophosphate; D004958:Estradiol; D014701:Veratridine; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D010741:Phospholipases A; D054467:Phospholipases A2; D010738:Type C Phospholipases