This study aimed to evaluate the influence of ovarian steroids on equine endometrial epithelial and stromal cells, specifically i) prostaglandin (PG) production in a time-dependent manner, ii) specific PG synthases mRNA transcription and protein expression, and iii) cell proliferation. After passage I, cells were exposed to vehicle, oxytocin (OT, positive control, 10(-7) M), progesterone (P4, 10(-7) M), 17β estradiol (E2, 10(-9) M), or P4+E2 for 12, 24, 48, or 72 h. Following treatment, PG concentration was determined using the direct enzyme immunoassay (EIA) method. Alterations in PG synthases mRNA transcriptions, PG synthases protein expression, and cell proliferation in response to the treatments were determined after 24 h using real-time PCR, western blot, or 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide respectively. After 24 h, E2 and P4+E2 increased PGE2 and PGF2α secretion as well as specific prostaglandin-endoperoxide synthase-2 (PTGS2), PGE2 synthases (PGES), and PGF2α synthases (PGFS) expression in the epithelial cells (P<0.05). Additionally, E2 and P4+E2 increased PTGS2 expression in stromal cells after 24 h (P<0.05). In stromal cells, P4+E2 increased PGE2 production as well as PGES expression after 24 h (P<0.05). Both E2 and P4+E2 increased PGF2α production by stromal cells after 24 h (P<0.05). Ovarian steroids affected proliferation of stromal and epithelial cells during the 24-h incubation period (P<0.05). We provide evidence that ovarian steroids affect PG production in equine endometrial cells, upregulating PTGS2, PGES, and PGFS expression. Ovarian steroid-stimulated PG production could be an important mechanism occurring in the equine endometrium that is involved in the regulation of the estrous cycle and early pregnancy.
Keywords: endometrium; mare; ovarian steroids; prostaglandin.