Abstract: Objective：To observe the expression of insulin receptor substrate-2 （IRS-2）on intrauterine growth retardation（IUGR），and to investigate molecular mechanisms for insulin resistance in IUGR rats. Methods：An IUGR animal model was established by protein malnutrition during pregnancy.Study the expression of IRS-2 by immunohistochemistry at newborn，at 3 weeks and 8 weeks respectively on control group fed with common diet and IUGR lowprotein diet group. Results：The level of protein of IRS-2 at newborn，3 weeks and 8 weeks of IUGR was significantly lower than that of control group respectively. Conclusion：IUGR can induce the obstacle of signal transduction and effecter molecule by impacting on IRS2，which might be one of the molecular mechanisms of IUGR with insulin resistance at adult.

Key words: Fetal growth retardation；Fetus/Embryology；Receptors, insulin；Rats；Animals, laboratory