Prostaglandin Metabolism in the Ovine Corpus Luteum: Catabolism of Prostaglandin F2α (PGF2α) Coincides with Resistance of the Corpus Luteum to PGF2α

Abstract To examine possible mechanisms involved in resistance of the ovine corpus luteum to the luteolytic activity of prostaglandin (PG)F2α, the enzymatic activity of 15-hydroxyprostaglandin dehydrogenase (PGDH) and the quantity of mRNA encoding PGDH and cyclooxygenase (COX-2) were determined in ovine corpora lutea on Days 4 and 13 of the estrous cycle and Day 13 of pregnancy. The corpus luteum is resistant to the action of PGF2α on Days 4 of the estrous cycle and 13 of pregnancy while on Day 13 of the estrous cycle the corpus luteum is sensitive to the actions PGF2α. Enzymatic activity of PGDH, measured by rate of conversion of PGF2α to PGFM, was greater in corpora lutea on Day 4 of the estrous cycle (P < 0.05) and Day 13 of pregnancy (P < 0.05) than on Day 13 of the estrous cycle. Levels of mRNA encoding PGDH were also greater in corpora lutea on Day 4 of the estrous cycle (P < 0.01) and Day 13 of pregnancy (P < 0.01) than on Day 13 of the estrous cycle. Thus, during the early estrous cycle and early ...