Objective: To investigate effects of Dendrobium nobile Lindl. alkaloids (DNLA) on blood glucose and gene expression of insulin receptor substrate 2(IRS-2) and insulin-like growth factor 1(IGF-1) in liver of rats with diabetes. Method: Male Spragye-Dawley rats were fed with high-fat diet for 6 weeks. Then streptozotocin(STZ) 40 mg·kg-1 was injected intraperitoneally once to induce diabetic rat model. Diabetic rats were randomly divided into model group

metformin (metformin 100 mg·kg-1) and DNLA 20

40

80 mg·kg-1 group. And normal control group was fed with basal feed. After intragastric administration of metformin

DNLA and isopyknic distilled water daily for 4 weeks to rats of metformin group

DNLA group and normal control group respectively

the fasting plasma glucose (FPG) and fasting insulin (FINS) were determined

and homeostasis model assessment of insulin resistance (HOMA-IR) were calculated. The expressions of IRS-2 mRNA and IGF-1 mRNA in liver were determined by real time RT-PCR. Result: Compared with the normal control group

the levels of FPG

FINS

HOMA-IR were significantly increased (P<0.05). The FPG

FINS and HOMA-IR were significantly decreased in the metformin group and DNLA 40

80 mg·kg-1 group compared with those in the model group(P<0.05). Contents of IRS-2 mRNA and IGF-1 mRNA in model group were decreased; compared with model group

contents of IRS-2 mRNA and IGF-1 mRNA in the metformin group and DNLA 40

80 mg·kg-1 group were increased. Conclusion: DNLA can significantly decrease the levels of FPG of diabetic rats

and its mechanism may be related with enhancing the expressional levels of IRS-2 mRNA and IGF-1 mRNA in liver

improvement of insulin resistance.