Irisin modulates granulosa cell function in chicken ovarian follicles: Effects on viability, gene expression, and progesterone secretion.

Irisin, a myokine/adipokine released during physical activity, has attracted attention for its regulatory effects on various physiological processes, including metabolism and reproduction. This study was performed to investigate the presence of fibronectin type III domain-containing protein 5 (FNDC5) in chicken granulosa cells (GCs) using immunocytochemistry and to assess the effect of irisin, the extracellular fragment of FNDC5, on these cells, which play a crucial role in progesterone (P4) production and follicle maturation. We measured cell viability, mRNA expression of the luteinising hormone receptor (LHR), the expression of steroidogenic genes (StAR, CYP11A1, and 3BHSD), and P4 secretion in GCs of chicken ovarian follicles. The results showed that irisin reduced the viability of all cultured GCs at different concentrations (0.5, 2.5, and 5 ng/mL). Real-time reverse transcription quantitative PCR demonstrated decreased expression of LHR and 3BHSD at 0.5 ng/mL irisin across GCs from preovulatory follicles of all stages (F3, F2 and F1), and elevated expression of StAR, 3BHSD, and LHR at 5 ng/mL in GCs from F1 follicles. Furthermore, irisin decreased P4 secretion from GCs isolated from F3 and F2 follicles, but increased the release of this hormone from F1 follicles at a 5 ng/mL concentration. These findings suggest that irisin may play a modulatory role in the maturation and ovulation of chicken ovarian follicles by influencing cell proliferation, gene expression, and hormone production depending on the dose and stage of follicle development.