The Effects of EPA and DHA on the Uterine Inflammatory Response in Mares during In Vitro Culture of Endometrial Tissue

Abstract

Uterine inflammation is one of the causes of a poor uterine environment. This can result in early embryonic loss in the mare due to an inhibition of or an increased secretion of prostaglandin F2α (PGF2α ). Oxytocin binds to endometrial cell receptors to activate prostaglandin synthesis. Increased secretion or accumulation of PGF2α within the uterus due to uterine inflammation can cause luteolysis and result in early embryonic loss. Supplementation with polyunsaturated fatty acids (PUFAs) has been shown to influence prostaglandin production in many species, although the effects on the mare remain unknown. Equine endometrial biopsies were collected and used to establish endometrial epithelial cell and explant cultures to determine the release of PGF2α and PGFM in response to oxytocin stimulation. Endometrial explant cultures were used to determine the inhibitory effects of Atosiban, an oxytocin receptor antagonist, and Indomethacin, a cyclooxygenase –2 inhibitor, on PGF2α secretion. Endometrial explant cultures were challenged with oxytocin (250 nM) and PGF2α concentrations were measured over time. The effects of PUFAs on equine endometrial prostaglandin production were determined using endometrial biopsies harvested on day two of behavioral estrus. Equine endometrial cells were established and shown to replicate in culture and on a basement membrane matrix. Equine endometrial explants stimulated with oxytocin had increased secretion of PGF2α and PGE2 and the secretion of PGF2α was inhibited through an oxytocin receptor antagonist and Cox inhibition. Endometrial explants stimulated with lipopolysaccharide had increased secretion of PGF2α and PGE2, however oxytocin stimulated to a greater extent than LPS. Supplementation with PUFAs, specifically DHA, decreased the secretion of PGF2α and PGE2, however AA and EPA failed to influence this response. Expression of mRNA was not influenced by fatty acid supplementation, however was altered by stimulus. Therefore DHA influences the inflammatory response in vitro through mechanisms other than enzyme expression. Decreased PGF2α production associated with PUFA supplementation in vivo, creates a likely approach for decreasing early embryonic loss associated with post breeding inflammation commonly seen in the equine industry.