Sex-steroid receptors, prostaglandin E2 receptors, and cyclooxygenase in the equine cervix during estrus, diestrus and pregnancy: Gene expression and cellular localization.

This study investigates how certain hormones and enzymes present in the mare’s cervix fluctuate during different reproductive phases, with an emphasis on the transition period before giving birth. It specifically looks at estrogen receptors α (ESR1) and β (ESR2), progesterone receptor (PGR), prostaglandin E2 type 2 (PTGER2) and type 4 (PTGER4) receptors, and cyclooxygenase-1 (PTGS1) and -2 (PTGS2).

Research Objectives and Methods

• This research was aimed at studying the changes in gene expression related to reproductive hormones in the equine cervix. Specifically, the researchers monitored the changes during three different stages: estrus (when mares are ovulating), diestrus (the resting period between estrus), and late pregnancy.
• By using quantitative PCR (qPCR), they compared the expression of hormones and enzymes including estrogen receptors, progesterone receptor, prostaglandin E2 receptors, and cyclooxygenases.
• Immunohistochemistry – a technique for identifying specific proteins in tissue via staining – was applied to localize the above-mentioned receptors within the tissue.

Key Findings

• The researchers found that the mRNA expression of ESR1 and PGR was greater during estrus and diestrus than in late pregnancy. This indicated that these hormones were less active in later stages of pregnancy.
• The expression of PTGER2 was observed to be highest in the stroma (structural part of the cervix) during late pregnancy. PTGS1 and PTGS2 levels were also found to be higher in late pregnancy compared to the estrus stage, but not diestrus.
• Immunolabeling showed consistent detection of ESR1, ESR2, PGR, PTGER2, and PTGER4 receptors in various parts of the cervix and in all assessed stages.

Conclusion

• The changes in hormone and enzyme levels during late pregnancy are likely associated with the preparation of the cervix for the birthing process. This finding contributes to our understanding of equine reproductive health and potentially could inform improved veterinary practices for pregnancy and parturition in horses.