Molecular Mechanisms Of Primordial Follicle Assembly Regulated By Insulin In Mice

Insulin is a protein secreted by pancreatic β-cells. It plays an important role in the regulation of ovarian function. However, the specific molecular mechanism of its function remains largely unknown. This study aimed to assess the effect of insulin on mouse folliculogenesis using in vitro ovary culture model. The results demonstrated that insulin promoted the proliferation of ovarian granulosa cells in vitro, and thereby accelerated the progress of folliculogenesis (the percentage of oocytes in cyst declined from42.6%to29.3%); however, the percentage of apoptotic oocytes increased after insulin treatment. Further investigation indicated that cell apoptosis occurred mainly in germ cell cysts. After3days of insulin treatment, estrogen in the culture medium of mouse ovaries significantly increased (p<0.01), while low dose estrogen promoted primordial follicle assembly in vitro.In conclusion, insulin promoted folliculogenesis via facilitating germ cell apoptosis within the cysts and up-regulating estrogen level.