Serum irisin and its regulation by hyperinsulinemia in women with polycystic ovary syndrome

Irisin is an adipokine/myokine which could be connected with insulin sensitivity. Polycystic ovary syndrome (PCOS) is characterized by oligo- or anovulation, polycystic ovary, hyperandrogenism and insulin resistance. The aim of the present study was to determine the relationship between serum irisin concentration and insulin sensitivity (M-ffm) as well as the effect of insulin infusion on circulating irisin levels in PCOS women as compared with healthy controls. Seventy seven women were enrolled in the study - 57 with PCOS and 20 healthy controls matched for BMI and age. Hyperinsulinemic euglycemic clamps were performed in all of the study participants. The serum concentrations of irisin at baseline and after the clamp, as well as changes of serum irisin concentration in response to insulin supplied during the clamp (Delta irisin), were estimated. The mean serum concentrations of irisin at baseline and after hyperinsulinemia were higher in PCOS women in comparison to the control group (p=0.01; p=0.006, respectively). Insulin infusion resulted in a decrease of serum irisin concentration only in the PCOS group (p=0.007). In the control group, Delta irisin positively correlated with M-ffm (r=0.56, p=0.009). In the entire group, multiple regression analysis showed that Delta irisin (beta=0.70, p=0.0002), FFAs 60' during the clamp study beta=-0.22, p=0.01), SHBG (beta=0.54, p<0.0001) and the interaction between A irisin and PCOS (beta=-0.67, p=0.0004) were significantly associated with M-ffm. The higher serum irisin concentrations at baseline and in response to insulin infusion might be secondary to insulin resistant conditions in PCOS women.