Fig. 5

A hypothetical model illustrating the function of hyperandrogenism and NPY regulating granulosa cells. A In normal condition, NPY has no significant influence on proliferation nor apoptosis. B Hyperandrogenism reduces NPY content in granulosa cells and induces NPY2R and NPY5R contents in granulosa cells. Under hyperandrogenism, NPY does not affect proliferation but reduces apoptosis of granulosa cells in autocrine manner. NPY2R or NPY5R might be involved in NPY-reduced apoptosis. NPY may contribute to follicle developmental failure of PCOS