Objective—To determine the effects of 2 conjugated linoleic acid (CLA) isomers (cis-9, trans-11 and trans-10, cis-12) on synthesis of prostaglandin (PG) E2 and F2 and expression of prostaglandin H synthase-2 (PGHS-2) of adult and fetal bovine endometrial epithelial cells in vitro. Sample—Primary cultures of endometrial epithelial cells obtained from 4 adult cows and 4 fetal bovine carcasses. Procedures—Cells were exposed to 0, 50, 100, or 200μM cis-9, trans-11 or trans-10, cis-12 CLA isomers for 24 hours. Culture media collected before and after 6 hours of stimulation of cells with phorbol 12-myristate 13-acetate were assayed to detect PGE2 and PGF2 via ELISA. After stimulation, cells were collected for western blot analysis to quantify PGHS-2. Results—Concentrations of PGF2 and PGE2 were significantly lower in culture media of adult and fetal endometrial epithelial cells exposed to any concentration of either CLA than they were in media of cells not exposed to CLAs. The trans-10, cis-12 CLA isomer seemed to decrease PG production more markedly than did the cis-9, trans-11 CLA isomer. Most concentrations of both CLAs significantly reduced culture media PGE2:PGF2 concentration ratios of cells. Exposure of cells to CLAs did not affect expression of PGHS-2 protein. Conclusions and Clinical Relevance—Results of this study indicated CLAs significantly decreased PGF2 and PGE2 concentrations and PGE2:PGF2 concentration ratios for cultures of adult and fetal endometrial epithelial cells with no apparent effect on PGHS-2 expression. Similar effects in cows could have effects on maternal recognition of pregnancy and immune function. (Am J Vet Res 2013;74:491–498)

Keywords