Luteinizing hormone and ovarian steroids affect in vitro prostaglandin production in the equine myometrium and endometrium.

This study explores how luteinizing hormone and ovarian steroids influence prostaglandin production within the myometrium and endometrium of mares. It discovered that these hormones affect the production of prostaglandins, key elements in the regulation of the oestrus cycle and establishment of pregnancy in horses.

Understanding the Study Objectives

• The study aims to understand how luteinizing hormone (LH) and ovarian steroids affect the production of prostaglandins (PGs), vital hormones in regulating the estrus cycle of mares, and establishing pregnancy.
• The focus is on understanding the impact of LH and ovarian steroids on specific myometrial and endometrial tissues related to PGE and PGF secretion.
• The researchers also aimed to evaluate how these hormones affect the transcription of specific genes responsible for prostaglandin synthesis, such as prostaglandin-endoperoxide synthase (PTGS2), PGE synthases (PGES), PGF synthases (PGFS), and PGI synthases (PGIS), in equine myometrial and endometrial explants (tissue samples).

Methodology and Approach

• Equine myometrial and endometrial tissues were collected during specific phases of the oestrus cycle: At the mid-luteal (n = 6) and follicular (n = 6) phases.
• These samples were then exposed to different substances, including a control (vehicle), arachidonic acid (positive control), LH, progesterone, and 17-β estradiol. This exposure occurred for 24 hours.
• After this time, the concentrations of PGF and PGE were determined through direct enzyme immunoassays, and any changes in PG synthase mRNA expression were identified using RT-qPCR.

Key Findings of the Study

• LH and progesterone increased PGE and PGF secretion in myometrial tissues during the mid-luteal phase. During the follicular phase, PG secretion was enhanced by LH and 17-β estradiol.
• In contrast, LH and 17-β estradiol increased PGE and PGF secretion in endometrial tissues during the mid-luteal phase, with 17-β estradiol enhancing PGE secretion during the follicular phase of the oestrus cycle.
• The results thus show that LH and ovarian steroids affect prostaglandin production in different ways, in equine myometrial and endometrial tissues, and also at the mRNA level.

Conclusion

• The research concludes that the equine myometrium can serve as an alternative source of prostaglandin production and plays a role in regulating uterus function during the oestrus cycle in mares.
• The effects of LH and ovarian steroids on prostaglandin production can potentially be key in better understanding and managing the reproductive processes in horses.