Tanshinone I alleviates insulin resistance in type 2 diabetes mellitus rats through IRS-1 pathway.

Tanshinone I from tanshen has been used in traditional Chinese medicine for treating cardiovascular diseases and inflammatory diseases. Given the link between inflammation and Type 2 diabetes mellitus (T2DM), we suspect that tanshinone I may have a beneficial effect on T2DM. This study was to investigate the potential effects of tanshinone I on T2DM and its underlying mechanism. T2DM was thus induced in Sprague-Dawley (SD) rats using streptozotocin (STZ) and high-fat diet. It was observed that T2DM rats had higher levels of total cholesterol (TC), nonesterified fatty acids (NEFAs), total triglyceride (TG) and total low density lipoprotein cholesterol (LDL-C) compared with normal, healthy SD rats. Treatment with tanshinone I decreased these levels and lowered blood glucose level in T2DM rats. In addition, enzyme-linked immunosorbent assay (ELISA) analysis showed that T2DM rats had elevated levels of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). Furthermore, Western blot analysis revealed that T2DM rats had enhanced nuclear translocation of NF-κB as well as elevated phosphorylation of Ser307 in IRS-1(insulin receptor substrate 1). Treatment by tanshinone I lowered the levels of IL-6 and TNF-α, decreased nuclear translocation of NF-κB as well as phosphorylation of Ser307 in IRS-1. These results demonstrated that tanshinone I could alleviate T2DM syndrome in rats.