Stimulation of Intracellular Free Ca2+ by Luteinizing Hormone in Isolated Bovine Luteal Cells
The mechanisms by which gonadotropins regulate the development and function of the corpus luteum are not completely understoon. Cyclic AMP is recognized as the primary ‘second messenger’ of luteinizing hormone (LH) action in the corpus luteum. We have recently reported that gonadotropins also stimulate the accumulation of ‘second messengers’ derived from phospholipase C (PLC) catalysed hydrolysis of phosphatidylinositol 4,5-bisphosphate (Davis et al., 1986a,c, 1987). Hydrolysis of this phospholipid liberates diacylglycerol and inositol 1,4,5-trisphosphate (IP 3) which serve to activate protein kinase C (Nishizuka, 1986) and mobilize intracellular Ca2 (Berridge, 1984), respectively. This newly described ‘second messenger’ system may be responsible for regulating cellular growth, metabolism and secretion in hormone, growth factor and neurotransmitter responsive tissues. The present studies were performed to examine the effect of LH on intracellular Ca concentrations in isolated bovine luteal cells. LH-induced increases in the levels of IP3 and cAMP were correlated with increases in intracellular Ca2+.
KeywordsLuteinizing Hormone Granulosa Cell Corpus Luteum Luteal Cell Inositol Trisphosphate
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