Biosynthesis of prostaglandins from arachidonic acid by the rat ovary

Biosynthesis of prostaglandins (PGs) from 14C-arachidonic acid was studied using homogenates of the ovaries from immature rats. In ascending order of metabolizing potency were, the ovaries from untreated rats, from rats treated with pregnant mare's serum gonadotropin (PMS), and from PMS-human chorionic gonadotropin (hCG) treated rats. Among the radioactive metabolites extracted, PGE2 and 6-keto PGF1 were purified and identified by silicic acid column-, thin layer-, reversed phase partition chromatographies, and radiogaschromatography. Production of PGE2 and 6-keto PGF1 was observed in homogenates of the ovaries of intact and PMS-hCG treated rats at conversion rates of 0.72; 0.43% and 7.62; 2.31%, but not by PMS treated rat ovaries. Treatment with PMS-hCG activated metabolism of arachidonic acid into radioactive metabolites including PGE2 and 6-keto PGF1 to a large extent. Accordingly, it is concluded that luteinizing hormone and hCG play a significant role in the biosynthesis of PGs by the rat ovarian follicle.