Decreased Circulating MANF in Women with PCOS is Elevated by Metformin Therapy and is Inversely Correlated with Insulin Resistance and Hyperandrogenism.

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a novel neurotrophic factor. Although recent studies have suggested that MANF appeared to be associated with insulin resistance, the results have been inconsistent. The aim of our study was to determine the serum MANF levels in women with PCOS and controls, to investigate their relationship to insulin resistance, and to evaluate circulating MANF changes with metformin intervention in PCOS women. We conducted a series of cross-sectional and interventional studies in 90 newly diagnosed patients with PCOS and 60 age- and gender-matched controls. Oral glucose tolerance test and euglycemic-hyperinsulinemic clamps were performed to assess the glucose tolerance and insulin sensitivity. Forty-three women with PCOS were randomly assigned to six months of oral metformin therapy. Serum MANF levels were significantly lower in women with PCOS than in controls. Serum MANF levels were positively correlated with M-value and negatively correlated with body mass index (BMI), body fat percentage (FAT), homeostatic model assessment of insulin resistance (HOMA-IR), and free androgen index (FAI). Multivariate stepwise regression demonstrated that serum MANF levels were independently associated with M-value and FAI. After six months of metformin treatment, there was a significant increase in serum MANF levels in PCOS women. Serum MANF levels are decreased in women with PCOS, and are reversely related to insulin resistance and hyperandrogenism. Metformin treatment elevates serum MANF levels and alleviates insulin resistance and hyperandrogenism in PCOS women.