Radix Astragali decreases the risk of insulin resistance in insulin-treated diabetic rats through lowering oxidative stress

Abstract

Objective Fluctuation of glucose levels is more likely to cause oxidative stress which contributes to the development of insulin resistance through activating c-Jun N-terminal kinase (JNK). Such antio xidants as vitamin C or vitamin E do not appear very helpful. Radix Astragali (RA) is an herbal medicine with antioxidative ability. The study was to explore whether RA would lower the risk of insulin resistance in diabetic rats. Methods Diabetic rats received RA, insulin or both RA and insulin after diabetes were induced in male Wistar rats. Serum levels of interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α), advanced glycation endproducts(AGEs) levels in kidney, the expression of insulin receptor (IR), insulin receptor substrate 1(IRS-1), p38 mitogen-activated protein kinase (MAPK), p-p38 MAPK, p-JNK, p-IRS-1 Ser307 , and p-IRS-1 Tyr612 in skeletal muscles were determined. Results Compared to diabetic rats treated with insulin, the diabetic rats treated with both insulin and RA demonstrated significantly lower levels of IL-6, TNF-α and AGEs (P<0.05), significantly lower activation of p-p38 MAPK and JNK (P<0.05), significantly higher expressions of IRS-1 (P<0.05), p-IRS-1 Tyr612, and significantly lower expression of p-IRS-1 Ser307 (P<0.05). Conclusions RA can lower the risk of insulin resistance through fighting oxidative stress in diabetic rats. Key words: ASTRAGALUS MEMBRANACEUS△/PD; Diabetes mellitus; Insulin resistance