Facilitated calcium mobilization and inositol phosphate production in the priming effect of LH-releasing hormone in the rat.
The ability of LHRH to induce Ca2+ mobilization and production of inositol phosphates in rat anterior pituitary tissue in vitro was investigated in relation to the self-priming effect of LHRH. Prior exposure to LHRH (which caused a characteristic potentiation of subsequent secretory responses) specifically enhanced LHRH-induced inositol phosphate production and mobilization of intracellular Ca2+ stores. LHRH-induced influx of Ca2+ through dihydropyridine-sensitive Ca2+ channels was unaltered, as was ligand binding to LHRH receptors. These data suggest that a novel facilitation of signalling may occur in the phospho-inositide-Ca2+ mobilization response mechanism during LHRH priming, and that this may represent an important means of regulating cellular responsiveness in gonadotrophs.
Mitchell
R
R
MRC Brain Metabolism Unit, University Department of Pharmacology, Edinburgh.
Johnson
M
M
Ogier
S A
SA
Fink
G
G
D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism / Q000494:pharmacology*; D066298:In Vitro Techniques; D007295:Inositol Phosphates / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000378:metabolism; D010052:Ovariectomy; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D013403:Sugar Phosphates / Q000378:metabolism*
D007295:Inositol Phosphates; D013403:Sugar Phosphates; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D002118:Calcium