Fig. 2

Pathophysioly of insuline resistance. This figure illustrates the complex interactions underlying the pathophysiology of PCOS. Insulin resistance and the resulting hyperinsulinemia are responsible for the majority of the changes found in PCOS. Insulin resistance in PCOS does not occur in all tissues, but rather appears to be tissue-specific. Skeletal-muscle and adipose tissue become insulin resistance resulting in decrease glucose uptake and increased lipolysis, respectively, whereas the ovary, adrenal and liver remain insulin sensitive. In PCOS, hyperinsulinemia occurs as a compensatory response to insulin resistance. This resulting hyperinsulinemia has a stimulatory effect on the ovaries and adrenal glands that leads to enhanced androgen production by these organs. More specifically, excess insulin enhances androgen production in ovarian theca cells in response to luteinizing hormone (LH) stimulation, resulting in follicular arrest and anovulation. In contrast hyperinsulinemia acts to suppress hepatic production of sex hormone-binding globulin (SHBG), the primary binding protein for testosterone in the serum. Therefore, insuline resistance whith compensatory hyperinsulinemia results in hyperandrogenemia