Abstract
Endometritis is one of the most important causes of infertility in mares. Mares may suffer from endometritis outside the breeding season; however, pathological condition is often undiagnosed in anestrus. The aim of this study was to examine whether the secretion profiles of prostaglandin F2α (PGF2α), prostaglandin E2 (PGE2), and a metabolite of prostacyclin I2 (6-keto-PGF1α) differ in endometrial tissue cultures of heavy draft mares in anestrus with endometritis compared to those without endometritis. The endometrial biopsies were collected from 51 heavy draft mares. Inclusion criteria for the control group were absence of endometritis confirmed by histology and no ovarian activity. Inclusion criteria for the experimental group were presence of endometritis showing polymorphonuclear cells and/or lymphocytes infiltration in endometrium and no ovarian activity. Retrospectively, 22 mares were enrolled in this study. The content of PGF2α (P < .05) and PGE2 (P < .001) in the culture medium was distinctly elevated in mares suffering from endometritis, compared to control mares. The relative mRNA abundance responsible for prostaglandins synthesis, that is, PGF2α synthase (PGFS; P < .01), PGE2 synthase (PGES; P < .01), and prostaglandin-endoperoxide synthase (PTGS2; P < .01), were also increased in endometrial tissue of mares with endometritis compared to control mares. The content of 6-keto-PGF1α (P < .0001) in endometrial tissue cultures from mares with endometritis was strikingly elevated compared to those without endometritis; however, plasma concentration of 6-keto-PGF1α was not significantly different between experimental and control groups. This leads to the conclusion that augmented endometrial secretion of PGF2α, PGE2, and 6-keto-PGF1α is associated with endometritis even in mares in anestrus.