Altering n-3 to n-6 polyunsaturated fatty acid ratios affects prostaglandin production by ovine uterine endometrium

Abstract

Consumption of n-3 polyunsaturated fatty acids (PUFAs) is considered beneficial to health but effects on fertility remain uncertain. This study investigated the effect of n-3 PUFA supplementation on endometrial prostaglandin (PG) production. Ovine uterine endometrial cells were cultured to confluence in DMEM/F12 medium containing 10% foetal bovine serum. Stromal and epithelial cell populations were confirmed by immunocytochemistry. Cultures were supplemented with 0, 20 or 100μM of α-linolenic acid (ALA), stearidonic acid (SDA), eicosapentaenoic acid (EPA) with lipopolysaccharide (LPS) at 0 and 0.1μg/ml, or different combinations of EPA with arachidonic acid (AA) in serum-free medium for 24h. PGs were quantified using radioimmunoassay and PG-endoperoxide synthase (PTGS) isoforms, PGE and PGF synthase (microsomal PGES1 and PGFS) mRNAs by qPCR. LPS increased PGE2 production significantly without changing PGF2α production, causing increased PGE2:PGF2α ratios. ALA and SDA increased PGE2, PGF2α and PGE2:PGF2α ratios (P<0.05–0.01) while EPA alone did not affect PG generation. AA significantly stimulated PTGS1 and PTGS2 mRNA expression and PGE2 and PGF2α production (P<0.01). The stimulatory effect of AA was attenuated by up to 80% (P<0.05) when AA was combined with EPA. The PGE2:PGF2α ratio was not affected by AA or EPA alone, but increased when these two PUFAs were combined (P<0.05). SDA and EPA decreased PTGS1 mRNA expression (P<0.05) but did not alter PTGS2 expression. EPA and AA up-regulated mPGES1 expression (P<0.05) without affecting PGFS expression. Since AA is preferentially incorporated in uterine endometrium to produce 2-series PGs, alteration of PG production by EPA may affect many reproductive processes.