Caspase-3-mediated apoptosis and cell proliferation in the equine endometrium during the oestrous cycle.

This research examines the hormonal regulation of cell death and proliferation in the endometrium tissue of horses during the oestrous cycle, using markers for cell death (caspase-3) and proliferation (PCNA). The study links these findings to dynamic changes in the endometrium across the cycle, indicating potential implications for the underlying cellular processes involved in equine fertility.

Background and Aims

• The study aims to investigate the regulation of cell growth and death in the endometrium of horses. Specifically, the study examines endometrial cell proliferation through the expression of the proliferating cell nuclear antigen (PCNA), and cell death through the expression of active caspase-3 and the apoptotic phenotype visualised by DNA fragmentation.
• The study also seeks to understand the correlation between these cellular processes and the dynamic changes in the equine endometrium throughout the oestrous cycle.

Methodology

• The endometria sampled in the study were assigned to follicular and luteal phases based on observed ovarian structures and plasma progesterone levels.
• The prevalence of cell proliferation and active caspase-3-mediated apoptosis in both phases of the oestrous cycle was assessed.

Findings

• Key findings of the study include the observation that cell proliferation, measured through PCNA expression, was higher in the luteal phase than in the follicular phase. The highest PCNA activity was recorded in the luminal and glandular structures of the endometrium.
• Active caspase-3 expression indicating apoptosis was higher in luminal epithelial and deep glandular cells during the luteal phase as opposed to the follicular phase, where stromal cells exhibited greater active caspase-3 expression.
• A few apoptotic endometrial cells were detected by terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labelling (TUNEL); these cells were primarily found in luminal and glandular structures.
• The research also noted a simultaneous increase in DNA, cell proliferation, and protein synthesis in the endometrium during the mid-luteal phase. The researchers interpreted this as indicative of cell hyperplasia at the time when the histotroph (uterine secretion) is needed for eventual embryo nourishment.

Implications and Conclusion

• The findings suggest that endometrial cell death and proliferation during the equine oestrous cycle is hormone-dependent and contributes to the dynamic changes observed in the tissue over the cycle.
• This has potential importance for understanding the complex cellular processes underlying equine fertility and could inform future research efforts and potentially fertility treatments in horses.