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

Age-related changes in follicle paracrine signalling are not defined, and follicular gene transcript abundance could predict oocyte viability. Granulosa cells from preovulatory follicles of mares considered Young (n=12; 4-14 years), Mid-aged (n=9; 15-19 years) and Old (n=14; 20-27 years) were evaluated for transcript abundance related to systemic and follicle-specific pathways. Gene transcript abundance for receptors of insulin, adiponectin and peroxisome proliferating factor-γ were higher or tended to be higher in Mid-aged or Old than Young mares. Transcript abundance for interleukin (IL)-6 was elevated in Old versus Young mares, and IL-6 signal transducer was elevated in Old versus younger groups. Expression of tumour necrosis factor (TNF) receptor superfamily member 1A was higher in Mid-aged than Young mares, whereas TNF-inducible gene 6 protein mRNA tended to decrease in Mid-aged versus Young and Old mares. Genes for LH receptor and steroidogenic acute regulatory protein tended to be increased in Old versus Mid-aged and Young mares, respectively. Young and Old mares had higher mRNA for tissue-type plasminogen activator than Mid-aged mares. Thioredoxin-2 mRNA was higher in Old than younger groups. We observed age-related changes in mRNA of receptors for metabolic hormones, inflammatory processes, steroidogenic hormones, tissue remodelling and mitochondrial function, which could contribute to and/or mark alterations in follicular function and fertility.