Pituitary adenylate cyclase-activating polypeptide increases [Ca2]i in rat gonadotrophs through an inositol trisphosphate-dependent mechanism

Article Article scientifique Article Pituitary adenylate cyclase-activating polypeptide increases [Ca2]i in rat gonadotrophs through an inositol trisphosphate-dependent mechanism eng 1994 author Rawlings Stephen Roy 28552 author Demaurex Nicolas 0000-0002-9933-6772 24642 author Schlegel Werner 26447 5680-5686 7907085 0021-9258 Pituitary adenylate cyclase-activating polypeptide (PACAP) increases cAMP production and stimulates hormone release from a variety of anterior pituitary cells. However, in anterior pituitary gonadotrophs PACAP stimulates oscillations in cytosolic free Ca2+ concentration ([Ca2+]i) that appear to be independent of cAMP. To study the mechanisms involved in this response, we used the patch-clamp technique to microperfuse various agents into single rat gonadotrophs while monitoring [Ca2+]i with microfluorometry. Extracellular application of PACAP to single gonadotrophs stimulated high amplitude (> 1 microM) oscillations in [Ca2+]i, which were blocked by intracellular application of GDP beta S (guanosine 5'-O-2-thiodiphosphate), indicating the involvement of a G-protein. To identify the intracellular messenger(s) involved, we microperfused gonadotrophs with cAMP, inositol 1,4,5-trisphosphate (Ins(1,4,5)P3), or heparin, an antagonist of the Ins(1,4,5)P3 receptor. A high concentration of cAMP (100 microM) had no significant effect on basal [Ca2+]i and did not alter the PACAP-stimulated Ca2+ response. Heparin, but not its inactive isoform, completely blocked the PACAP-stimulated increase in [Ca2+]i, while Ins(1,4,5)P3 stimulated oscillations in [Ca2+]i very similar to those observed in response to PACAP. These results strongly suggest that PACAP mobilizes Ca2+ through an Ins(1,4,5)P3-dependent mechanism. The fact that PACAP stimulates two signaling pathways in pituitary cells could substantially enhance the signaling potential of this hypothalamic peptide. Animals Calcium/metabolism Cells, Cultured Cyclic AMP/metabolism GTP-Binding Proteins/metabolism Inositol 1,4,5-Trisphosphate/metabolism Male Neuropeptides/antagonists & inhibitors/physiology Neurotransmitter Agents/antagonists & inhibitors/physiology Pituitary Adenylate Cyclase-Activating Polypeptide Pituitary Gland, Anterior/cytology/drug effects/metabolism Rats Rats, Sprague-Dawley Dewey 612 134 Département de physiologie cellulaire et métabolisme 21C false 168 Signaux intracellulaires 210 The Journal of biological chemistry 269 8 28ccf247-8e37-4b95-8135-d6de494c0acf Article (Published version) Public Pituitary adenylate cyclase-activating polypeptide increases [Ca2]i in rat gonadotrophs through an inositol trisphosphate-dependent mechanism.pdf 825837 application/pdf openAccess Faculté de médecine / Section de médecine fondamentale / Département de physiologie cellulaire et métabolisme

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Pituitary adenylate cyclase-activating polypeptide increases [Ca2]i in rat gonadotrophs through an inositol trisphosphate-dependent mechanism	The Journal of biological chemistry			1994	575	484

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Rawlings, Stephen Roy