Effect of folic acid plus glycine supplement on uterine prostaglandin and endometrial granulocyte-macrophage colony-stimulating factor expression during early pregnancy in pigs

The objective was to determine the effects of folic acid+ glycine supplement on uterine metabolism of prostaglandin and mRNA expression of endometrial granulocyte-macrophage colony-stimulating factor (GM-CSF) in nulliparous (NYL) and multiparous Yorkshire-Landrace (YL) sows, and in multiparous Meishan-Landrace sows (ML). In each of these three groups, sows were randomly assigned to two treatments: 15 ppm folic acid + 0.6% glycine or no supplement. The dietary supplement was given from the estrus before mating to slaughter on Day 25 of pregnancy. At slaughter, endometrial tissue was collected to determine endometrial expression levels of GM-CSF mRNA, cyclooxygenase-1 (COX 1) and -2 (COX2) and to evaluate in vitro endometrial secretion of prostaglandin E-2 (PGE(2)) secretion. Allantoic fluid samples were also collected to determine the kconcentration of PGE(2), prostaglandin F-2alpha. (PGF(2alpha)), estradiol-17beta (E-2), progesterone( P-4), and transforming-growth factor-beta(2) (TGF-beta(2)). The allantoic contents of PGF(2alpha), E-2 and P-4,P- and endometrial in vitro secretion of PGE(2) were not significantly influenced by the folic acid + glycine supplement. The folic acid + glycine supplement tended (P < 0.07) to increase allantoic content of PGE(2) and TGF-beta(2) in all sows and increased (P < 0.05) endometrial expression of COX2, especially in NYL sows. The endometrial expression of COX1 was decreased (P < 0.05) by folic acid + glycine supplement, especially in multiparous YL sows. The allantoic contents of PGE2 and PGF(2alpha), were not significantly affected by sow type. However, NYL sows had higher (P < 0.05) endometrial in vitro secretion of PGE(2,) and allantoic content of P4 than multiparous YL and ML sows.