title: Gonadotropin-releasing hormone-stimulated phosphoinositide hydrolysis in the anterior pituitary. Modulation by protein kinase C but not by cyclic nucleotides.
abstract: Gonadotropin-releasing hormone (GnRH) produces a rapid and concentration-dependent hydrolysis of polyphosphoinositides in rat anterior pituitary cells in culture. Evaluation of the action of the decapeptide by measurement of [3H]-inositol phosphates and of prelabeled phosphoinositides demonstrated an effect on phosphatidylinositol-4,5-bis-phosphate and phosphatidylinositol-4-phosphate earlier than on phosphatidylinositol. The receptor antagonist [D-pGlu1,D-Phe2,D-Trp3,6]-luteinizing hormone-releasing hormone blocked the effect of GnRH on [3H]-inositol phosphate production. Protein kinase C activators attenuated GnRH-induced phosphoinositide hydrolysis, while neither cyclic AMP analogs nor cyclic GMP analogs were effective. These results indicate that phosphoinositide hydrolysis represents an important postreceptor transducing mechanism for GnRH action at the gonadotroph and that protein kinase C (but not cyclic nucleotides) may exert a negative feedback control on GnRH receptor-coupling mechanisms.
authors.affiliation: Department of Pharmacology, University of Catania, Italy.
authors.forename: M A
authors.initials: MA
authors.lastname: Sortino
authors.forename: W S
authors.initials: WS
authors.lastname: Evans
authors.forename: C
authors.initials: C
authors.lastname: Speciale
authors.forename: M O
authors.initials: MO
authors.lastname: Thorner
authors.forename: U
authors.initials: U
authors.lastname: Scapagnini
authors.forename: R M
authors.initials: RM
authors.lastname: MacLeod
authors.forename: P L
authors.initials: PL
authors.lastname: Canonico
mesh_terms: D000818:Animals; D001676:Biofeedback, Psychology; D002478:Cells, Cultured; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D006868:Hydrolysis; D007295:Inositol Phosphates / Q000096:biosynthesis; D007986:Luteinizing Hormone / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism*; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011966:Receptors, LHRH / Q000502:physiology
chemical_list: D007295:Inositol Phosphates; D010716:Phosphatidylinositols; D011966:Receptors, LHRH; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone