Effects of prostaglandins E2 and F2 alpha on progesterone metabolism by rat granulosa cells.

Rat granulosa cells were cultured with or without PGE2 and/or PGF2 alpha. Accumulation of endogenous progesterone and 20 alpha-hydroxy-4-pregnen-3-one was determined. Additionally, [4-14C]progesterone metabolism was assessed. PGE2 increased progesterone accumulation, in part, by decreasing progesterone catabolism to 20 alpha-reduced progestins. In contrast, PGF2 alpha stimulated 20 alpha-hydroxysteroid dehydrogenase activity, thus increasing progesterone catabolism. Combined treatment with PGE2 and PGF2 alpha augmented progesterone accumulation to levels above controls but below those attained with PGE2 alone. These data indicate that PGE2 and PGF2 alpha exert opposite effects on progesterone production and catabolism and that the ratio of PGE2 to PGF2 alpha in the local granulosa cell milieu may be of importance in determining overall progesterone output.