Gonadotropin Action in Isolated Ovarian Luteal Cells: The Intermediate Role of Adenosine 3′, 5′ Cyclic Monophosphate in Hormonal Stimulation of Progesterone Synthesis
Recent studies in several endocrine target cells have revealed moderate to marked dissociations between steroidogenesis and cAMP formation during hormone action (1–3). In the corpus luteum, low concentrations of LH or hCG have been found to evoke full steroidogenic responses with little or no detectable change in cAMP formation (4). However, a rise in protein kinase activity has been observed in corpus luteum slices incubated with gonadotropin concentrations which produce a dose-related stimulation of progesterone synthesis, albeit in the absence of a discernible rise in cAMP (5). Such findings suggest that an increase in cAMP synthesis or turnover is stimulated by even the lowest doses of hCG that evoke a steroid response, and that measurement of this change should be possible under. appropriate experimental conditions. A similar dissociation between steroidogenesis and cAMP during hormone action in the testis and adrenal has been recently resolved by optimization of incubation conditions and detailed analysis of cAMP levels in hormone-stimulated Leydig cells and and adrenal fasciculata cells (6,7). To evaluate the role of cAMP during hormone action in ovarian luteal tissue, we have analyzed the relationships between cAMP production and binding to protein kinase receptors, and stimulation of progesterone synthesis in isolated luteal cells.
KeywordsCorpus Luteum cAMP Production Luteal Cell Progesterone Production cAMP Receptor Protein
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