Abstract: Objective： To study the effect of metformoin on the expression of insulin receptor substrate-1 （IRS-1） and extracellular signal-regulated kinase-2 （ERK-2） in ovarian granulosa cells of the patients with polycystic ovarian syndrome （PCOS）． Methods：Granulosa cells were collected from PCOS patients during IVF-ET. Those granulosa cells from non-PCOS patients during IVF-ET were used as control. After in vitro treated by metformin for 48 h, the cultured granulose cells were examined for IRS-1 and ERK-2 mRNA expression by real-time quantitative PCR. Results：The expression levels of IRS-1 and ERK-2 mRNAs in the granulosa cells of PCOS patients were higher than those in control group （Ｐ＜０．０５）. The level of IRS-1 mRNA was increased by metformoin treatment, while the level of ERK-2 mRNA was decreased（P＜0.05）. Conclusions：Metformoin may alleviate the pathological state of insulin resistance in ovarian of PCOS patients by decreasing the activity of MAPK insulin signaling pathway, which has a negative effect on PI3K pathway.

Key words: Polycystic ovary syndrome, Fertilization in vitro, Embryo transfer, Receptor, insulin, Extracellular signal-regulated MAP kinases