Effect of irisin on ovarian phosphatidylinositol-3-kinase/protein kinase B signaling pathway and mitogen-activated protein kinase/extracellular signal-regulated kinase pathways of rats with polycystic ovary syndrome.

Objective: To investigate the independent effects of irisin on insulin resistance (IR) in ovary of polycystic ovary syndrome (PCOS) and explore possible pathways.

Methods: We established PCOS medel using Poretsky L's method, then PCOS rats were randomly divided into model group (M) and irisin group (I), and normal rats (N) were used as the control. Then rats in the group I were injected with recombinant irisin. Then the levels of circulating fasting blood glucose (FBG), fasting insulin (FINS), homeostasis model assessment of IR (HOMA-IR) and PI3K/AKT and MAPK/ERK pathways in each group were observed, as well as the effects of irisin on the levels of circulating HOMA-IR and PI3K/AKT and MAPK/ERK pathways in ovary of PCOS rats were evaluated.

Results: Compared with normal group, levels of FBG, FINS, and HOMA-IR of model group were significantly increased (p < 0.001, p < 0.001, and p < 0.001, respectively), levels of average optical density by IHC of p-PI3K, PI3K, p-AKT, and AKT (p = 0.015, p = 0.010, p = 0.005, and p = 0.009, respectively) and levels of mRNA concentration of PI3K and AKT (p = 0.001, and p = 0.005, respectively) were decreased, while the levels of average optical density of p-ERK, ERK (p = 0.011, and p = 0.013, respectively) and level of mRNA concentration of ERK (p < 0.001) were increased in ovary. After irisin intervention, compared with model group, levels of FBG, FINS, and HOMA-IR of rats in irisin group were significantly decreased (p = 0.001, p < 0.001, and p < 0.001, respectively), levels of average optical density by IHC of p-PI3K, PI3K, p-AKT, and AKT (p = 0.030, p = 0.024, p = 0.012, and p = 0.025, respectively) and levels of mRNA concentration of PI3K and AKT (p = 0.002, and p = 0.003, respectively) were significantly increased, while the levels of average optical density of p-ERK, ERK (p = 0.004, and p = 0.026, respectively) and level of mRNA concentration of ERK (p = 0.001) were significantly decreased.

Conclusion: Our study demonstrated that irisin could not only improve circulating insulin resistance, but may also improve ovarian IR through an increase in the activity of PI3K/AKT signaling and a decrease of MAPK/ERK signaling.