Evidence for a PGF2a auto amplification system in the endometrium in mares.
In mares, prostaglandin F2a (PGF2a) secreted from the endometrium is a major luteolysin. Some domestic animals have an auto amplification system in which PGF2a can stimulate its own production. Here, we investigated whether this is also the case in mares. In an in vivo study, mares at the mid luteal phase (days 6 8 of estrous cycle) were injected i.m. with cloprostenol (250 ug) and blood samples were collected at fixed intervals until 72 h after treatment. Progesterone (P4) concentrations started decreasing 45 min after the injection and continued to decrease up to 24 h (P 0.05) In turn, 13,14 dihydro 15 keto PGF2a (PGFM) metabolite started to increase 4h after an injection and continued to increase up to 72 h (P 0.05) PGF receptor (PTGFR) mRNA expression in the endometrium was significantly higher in the late luteal phase than in the early and regressed luteal phases (P 0.05) In vitro, PGF2a significantly stimulated (P 0.05) PGF2a production by endometrial tissues and endometrial epithelial and stromal cells and significantly increased (P 0.05) the mRNA expression of prostaglandin endoperoxide synthase 2 (PTGS2) an enzyme involved in PGF2a synthesis in endometrial cell. These findings strongly suggest the existence of an endometrial PGF2a auto amplification system in mares.
Reproduction