Regulation of the Corpus Luteum by Protein Kinase C. II. Inhibition of Lipoprotein-Stimulated Steroidogenesis by Prostaglandin F2α1

Open Access
Publisher Website
Google Scholar
Abstract
This study was designed to examine the antisteroidogenic action of prostaglandin (PG) F2α on ovine luteal cells in vitro. Purified populations of large and small steroidogenic luteal cells were treated with lipoproteins, luteinizing hormone (LH), and/or PGF2α. To investigate the involvement of the protein kinase C (PKC) pathway in hormone action, luteal cells were made PKC-deficient by treatment for 12 h with 1 μM phorbol-12-myristate-13-acetate. Progesterone production by nonstimulated large and LH-stimulated small luteal cells was significantly increased by treatment with high- and low-density lipoprotein (HDL, 5-fold increase; LDL, 2-fold increase). PGF2α inhibited (p < 0.0001) progesterone production by HDL-stimulated large luteal cells in a dose-dependent manner, with 60 nM causing maximal inhibition. No effect of PGF2α (20nM-20 μM) was found on production of progesterone by HDL-stimulated, PKC-deficient large cells or by LH- and HDL-stimulated small luteal cells. These results suggest that PGF2α has a direct antisteroidogenic effect on the large luteal cell that is mediated through the PKC second messenger pathway.