Schisandra Chinensis Acidic Polysaccharide Improves the Insulin Resistance in Type 2 Diabetic Rats by Inhibiting Inflammation

摘要

Polysaccharide from Schisandra chinensis has the effect of lowering blood glucose and improving insulin resistance (IR). However, its underlying mechanism remains unclear. In this study, a rat model of type 2 diabetes (T2D) was created to explore whether S. chinensis acidic polysaccharide (SCAP) would improve the IR in T2D rats by inhibiting inflammation. A combination of a high-fat diet and low dose of streptozotocin (STZ, 30 mg/kg, intraperitoneally) were administered to rats for establishing the T2D model. Then, these T2D rats were orally administered with SCAP (25, 50, or 100 mg/kg) for 8 weeks. The results indicated that SCAP significantly lowered the fasting blood glucose, elevated the fasting insulin, and improved glucose tolerance. SCAP also decreased the serum interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), C-reactive protein (CRP), and nuclear factor-kappa B (NF-kappa B) levels, as well as their mRNA expression in the liver tissue. Further, SCAP significantly inhibited the upregulation of phosphorylated c-Jun N-terminal kinase (p-JNK) and NF-kappa B protein, and it increased phosphorylated insulin receptor substrate-1 (p-IRS-1), phosphorylated phosphatidylinositol 3-kinase (p-PI3K), and phosphorylated protein kinase B (p-AKT) protein expression levels significantly. These results suggest that SCAP improves the IR in T2D rats by inhibiting inflammation.