Abstract
An in vitro superfusion system was used in an attempt to identify the cellular systems involved in the Ca2+ dependence of gonadotropin-releasing hormone (GnRH) actions in the frog, Rana pipiens. Superfusion with 5 microM A23187 (a calcium ionophore) or phorbol myristate acetate (an analog of diacylglycerides) caused marked increases in luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion. Exclusion of Ca2+ from the medium prevented the stimulatory effects of PMA. The potent stimulator of adenylate cyclase, forskolin, caused only slight stimulation of LH and FSH secretion, which was also prevented by removal of Ca2+. The cytoskeletal disruptive agents colchicine, nocodazole, and cytochalasin B, and the calmodulin inhibitors, trifluoperazine and pimozide, had no significant effects on the action of GnRH. Overall, these results indicate that the major mechanisms of Ca2+ involvement in the response to GnRH by the frog pituitary are similar to that of mammals, with the possible exceptions of lesser roles for calmodulin and the cytoskeleton in the frog. The study suggests that polyphosphatidyl-inositol-diacylglyceride metabolism may be critical in understanding the mechanism of GnRH action in frogs.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
