Hormone-independent activation of adenylate cyclase in large steroidogenic ovine luteal cells does not result in increased progesterone secretion

Endocrinology
P B HoyerG D Niswender

Abstract

The role of cAMP in controlling steroidogenesis in small and large ovine luteal cells was examined. Corpora lutea collected from superovulated ewes (9-11 days postovulation) were dissociated, and the two cell types were purified by elutriation. Both cell types were incubated for 0.5, 1, 2, and 4 h at 37 C with ovine LH (100 ng/ml), cholera toxin (100 ng/ml), or forskolin (50 microM). At each time point, progesterone levels were measured in the medium. Adenylate cyclase activity and cAMP concentrations in the cells and incubation medium were also determined. Progesterone secretion by small cells was significantly stimulated by ovine LH (up to 7.3-fold), cholera toxin (up to 4.2-fold), and forskolin (up to 4.5-fold) during the 4-h incubation. Intracellular levels of cAMP were significantly elevated in the small cells by ovine LH (up to 2.5-fold) and forskolin (up to 5.6-fold). Accumulation of cAMP in medium after incubation of small cells was also significantly stimulated by ovine LH (up to 215-fold), cholera toxin (up to 93-fold), and forskolin (up to 1105-fold). Adenylate cyclase activity, however, was only significantly stimulated by cholera toxin (2.6-fold) and forskolin (3.8-fold). None of the treatments stimulated progester...Continue Reading

Citations

Apr 1, 1989·Molecular and Cellular Endocrinology·P B Hoyer, W Kong
Nov 1, 1993·The Journal of Steroid Biochemistry and Molecular Biology·A V Sirotkin, J Nitray
Oct 1, 1984·Proceedings of the National Academy of Sciences of the United States of America·M ShemeshJ F Strauss
Apr 13, 2010·Prostaglandins & Other Lipid Mediators·Y S WeemsC W Weems
Jun 1, 1992·Molecular and Cellular Endocrinology·S E NelsonM Hunzicker-Dunn
Mar 1, 1986·Journal of Dairy Science·M F Smith
Jan 5, 2000·Physiological Reviews·G D NiswenderE W McIntush

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