Age-associated changes in granulosa cell transcript abundance in equine preovulatory follicles.

The research determines how age-related changes impact the abundance of gene transcript in granulosa cells of preovulatory follicles in horses, which could predict the viability of an oocyte.

Methods

• The study sourced granulosa cells from preovulatory follicles in three age groups of mares: Young (4-14 years), Mid-aged (15-19 years), and Old (20-27 years).
• A gene transcript abundance related to systemic and follicle-specific pathways was evaluated for each age group.

Results

• Gene transcript abundance for insulin receptors, adiponectin, and the peroxisome proliferating factor-γ was higher or tended to be higher in Mid-aged or Old mares compared to Young mares.
• Interleukin (IL)-6 transcript abundance was higher in Old mares compared to Young mares. Similarly, IL-6 signal transducer levels were elevated in Old mares compared to the other groups.
• Tumor necrosis factor (TNF) receptor superfamily member 1A expression was higher in Mid-aged mares compared to Young mares, while TNF-inducible gene 6 protein mRNA tended to decrease in Mid-aged mares compared to both Young and Old groups.
• Genes for LH (luteinizing hormone) receptor and steroidogenic acute regulatory protein were more abundant in Old mares compared to Mid-aged and Young mares, respectively.
• Both Young and Old mares exhibited higher mRNA for tissue-type plasminogen activator than Mid-aged mares. Thioredoxin-2 mRNA was higher in Old mares compared to the other groups.

Conclusions

• The research noticed age-related changes in mRNA of receptors for metabolic hormones, inflammatory processes, steroidogenic hormones, tissue remodelling, and mitochondrial function.
• These changes could contribute to modifications in follicular function and fertility as mares age.
• Discovering these RNA transcript abundance changes can aid in predicting and understanding age-related fertility changes in horses.