Effects of LH and PGF2alpha in equine dominant follicles observed by MDS.

The article explores the use of Microdialysis System (MDS) to investigate local hormonal secretion in pre-ovulatory follicles of mares. Results revealed that the Luteinizing Hormone (LH) stimulates theca interna cells and that Prostaglandin F2alpha (PGF2alpha) seems to play an intermediary role in inducing steroid hormone production and luteinization of follicular cells.

Investigation Tool – Microdialysis System (MDS)

• In this research, the scientists used a new method known as Microdialysis System, or MDS, to study the secretion of molecules between different populations of cells.
• Specifically, the researchers were interested in the process of hormonal secretion at the follicular wall, which has been poorly understood up to this point.

Studying Hormone Release from Pre-Ovulatory Follicles

• The team decided to focus on pre-ovulatory follicles in mares. To analyze them, follicles larger than 30 mm were isolated from the ovary and the follicular fluid was collected for a hormone assay.
• These fluids, collected from follicles of varying sizes – small, middle, and large – were then analyzed using EIA (Enzyme-Linked Immunosorbent Assay).

Role of Progesterone (P4), Androstenedione (A4), Estradiol (E2) and Prostaglandin F2alpha (PGF2alpha)

• The concentration levels of the hormones Progesterone (P4) and Prostaglandin F2alpha (PGF2alpha) were found to be similar across follicles of all sizes.
• The release of another hormone Androstenedione (A4) was observed in middle and large follicles, and the release of Estradiol (E2) was seen in middle-sized follicles, with its concentration higher in large follicles as compared to middle ones.

Effect of Infusion of LH and PGF2alpha

• The scientists then cut the follicular wall and incubated it for the Microdialysis System. On infusing the luteinizing hormone (LH), there was an observed increase in the release of P4 and A4 hormones. Notably, the release of PGF2alpha also saw a substantial increase following LH infusion.
• Moreover, when PGF2alpha was infused, the release of P4 and A4 increased, but there was no observed change in the release of E2.

Implications of the Study

• The results from this research suggest that in pre-ovulatory follicles, LH may stimulate theca interna cells – cells within the ovarian follicle that are involved in hormone production.
• Additionally, the research found that the PGF2alpha seems to play an intermediary role in inducing steroid hormone production and the luteinization of follicular cells. Luteinization refers to the process by which the ovarian follicles mature and release eggs.
• However, the mechanisms involved in the selection of large follicles for ovulation remain unclear and pose an ongoing challenge in reproductive research.