Characterization of matrix metalloproteinase-2 and matrix metalloproteinase-9 and their inhibitors in equine granulosa cells in vivo and in vitro.

The article investigates the role of matrix metalloproteinases (MMP) and their inhibitors (TIMP) in the evolution and atresia of follicles in horses. The study concluded that changes in the function of MMP-2 and MMP-9 may be necessary for tissue reshaping leading to ovulation in horses.

Research Methodology

• Horse granulosa cells and follicular fluid were collected from medium, large healthy, and atretic follicles and snap-frozen for in vivo studies or cultured for 48 hours for in vitro studies.
• Testing was conducted to determine the gene expression and protein enzyme activity of MMP-2 and MMP-9 and TIMP-1 and TIMP-2.
• Hormone concentrations were also measured for progesterone and estradiol, and follicle dynamics were used to classify follicles.

Findings and Analysis

• In vivo studies, increased MMP-2 and TIMP-2 expression was found in large preovulatory follicles, while TIMP-1 decreased.
• There was a noticeable decrease in the ratio of MMP-2:TIMP-2 expression in medium-healthy and large-preovulatory follicles, while the MMP-9:TIMP-1 ratio increased only in large-preovulatory follicles.
• Highest concentrations of estradiol were found in the fluid of large healthy and large preovulatory follicles. The least estradiol concentrations were found in medium-atretic follicles, both in vivo and in vitro.
• In healthy follicles, the follicle diameter was connected with estradiol concentration, the estradiol:progesterone ratio, MMP-9 and TIMP-1 expression, and MMP-2 and MMP-9 protein activity in vivo.
• In vitro studies found an increase in the MMP-9:TIMP-1 expression ratio in medium-healthy follicles and a decrease in TIMP-2 expression in large-preovulatory follicles.
• MMP-9 protein activity was decreased in large healthy follicle cell media samples compared to those from medium healthy follicles in in vitro studies.

Conclusions

• The results indicate that changes in the activities of MMP-2 and MMP-9 may be vital to tissue reorganization necessary for ovulation in a horse’s ovary.
• The balance between the matrix metalloproteinases and their inhibitors play a critical role in follicular development and atresia.
• The research provides potential indicators of follicular health and viability, such as hormone concentrations and MMP and TIMP ratios, that can be tracked in both in vivo and in vitro settings.