Evidence for a PGF2α auto-amplification system in the endometrium in mares.

The research article explores the possibility of an auto-amplification system in mares, where prostaglandin F2α (PGF2α), a hormone secreted by the endometrium (inner lining of the uterus), can stimulate its own production. The study includes both in-vivo and in-vitro experiments investigating this system, and the findings indicate a strong potential of the existence of PGF2α auto-amplification in mares.

Study Design and Methodology

• The researchers conducted an in-vivo experiment where mares in the mid-luteal phase (days 6-8 of their estrous cycle) were injected with cloprostenol, a synthetic version of PGF2α. After the injection, the levels of progesterone (P4) and 13,14-dihydro-15-keto-PGF2α (PGFM, a metabolite of PGF2α) were measured over a 72-hour period.
• An in-vitro study was also performed where PGF2α was used to stimulate endometrial tissue and cells to track the production of PGF2α and prostaglandin-endoperoxide synthase-2 (PTGS2) enzyme that contributes to the synthesis of PGF2α.

Results and Findings

• The findings from the in-vivo study showed that progesterone levels started to decrease 45 minutes after constenol injection and continued to decrease up to 24 hours. Meanwhile, the PGFM metabolite started increasing 4 hours after the injection and continued to increase up to 72 hours.
• The researchers also found that the expression of prostaglandin F receptor (PTGFR) mRNA in the endometrium was notably higher in the late luteal phase compared to both the early and regressed phases, indicating an increased production of PGF2α during that period.
• In the in-vitro experiment, it was found that PGF2α notably stimulated the production of PGF2α by endometrial tissues and cells. It also increased the mRNA expression of PTGS2, the enzyme involved in PGF2α synthesis.
• These findings strongly suggest the existence of a PGF2α auto-amplification system in the endometrium of mares, where PGF2α stimulates its own production.