Insulin Reduces Reaction of Follicular Granulosa Cells to FSH Stimulation in Women with Obesity-Related Infertility during IVF

Abstract

Women with obesity usually need larger doses of FSH for ovarian stimulation, resulting in poor outcomes; however, the mechanism is still unclear. Objective: To investigate the molecular regulation of FSH receptor (FSHR) expression associated with obesity. Design: Case-control study to improve in vitro fertilization (IVF) outcomes. Patients: Women with obesity (82) and women who were overweight (457) undergoing IVF and 1790 age-matched controls with normal weight from our reproductive medicine center. Main Outcome Measures: FSHR expression was decreased in parallel with bodymass index (BMI),whereas the estradiol (E2) level on the human chorionic gonadotropin (hCG) trigger day was significantly lower. Results: FSHR expression in human granulosa cells (hGCs), both mRNA (P = 0.02) and protein (P = 0.001) levels, was decreased in women who were overweight or obese. Both insulin (P , 0.001) and glucose (P = 0.0017) levels were positively correlated with BMI in fasting blood and follicle fluids (FFs) but not with FFs leptin level. We treated human granulosa-like tumor cells (KGN) cells with insulin; E2 production was compromised; the level of phosphorylated (p)-protein kinase B (p-Akt2) decreased, whereas p-glycogen synthase kinase 3 (GSK3) increased; and there were similar changes in hGCs from women with obesity. Stimulated hGCs from women with obesity with compound 21 (CP21), an inhibitor of GSK3b, resulted in upregulated b-catenin activation and increased FSHR expression. CP21 also increased the expression of insulin receptor substrate 1 and phosphatidylinositol 3-kinase (PI3K), as well as p-Akt2.