Tight Coupling of Gonadotropin-Releasing Hormone Receptor to Stimulated Phosphoinositide Turnover and Antigonadotropic Action in Granulosa Cells
作者:
Atsushi Imai,
Koji Iida,
Teruhiko Tamaya,
期刊:
Gynecologic and Obstetric Investigation
(Karger Available online 1992)
卷期:
Volume 33,
issue 1
页码: 36-41
ISSN:0378-7346
年代: 1992
DOI:10.1159/000294844
出版商: S. Karger AG
关键词: Gonadotropin-releasing hormone;Phosphoinositide;Granulosa cells
数据来源: Karger
摘要:
Gonadotropin-releasing hormone (Gn-RH) stimulates phosphoinositide turnover by binding to its specific receptor and suppresses gonadotropin-dependent maturation and steroidogenesis in granulosa cells. This study was undertaken to determine whether persistent receptor occupancy was necessary for Gn-RH to exert such actions on rat granulosa cells, or whether Gn-RH actions were continued by a first and transient stimulation by Gn-RH, using a competitive antagonist, antide. Gn-RH stimulated [32P]phosphate incorporation into phosphatidylinositol (Ptdlns), which could be terminated by displacement of previously bound Gn-RH from its receptor by antide and restarted by reoccupying the receptors with Gn-RH. Antide could prevent Gn-RH-stimulated Ptdlns radiolabelling whenever it was added to incubations. An identical effect of antide was observed also in the antifollicle-stimulating hormone (FSH) action of Gn-RH. FSH markedly stimulated aromatase activity, and Gn-RH caused a time- and dose-dependent inhibition of FSH action. Estrogen production was quenched by Gn-RH and restarted at a time when Gn-RH was removed from its receptor by antide. These two responses associated with the occupancy of Gn-RH receptor provide the evidence in favor of a tight coupling of stimulated Ptdlns turnover to suppression of aromatase activation. These data of required continued activation of receptor might exclude the possibility that hypothalamic Gn-RH participated in the control of steroidogenesis in the ovary.
点击下载:
PDF
(2558KB)
返 回