Antidiabetic effects of pterostilbene through PI3K/Akt signal pathway in high fat diet and STZ-induced diabetic rats.

Pterostilbene (PTE) is a natural dimethylated analog of resveratrol, which exerts antioxidative, hypolipidemic and hypoglycemic effects; however, the underlying mechanism is not yet clear. In this study, we evaluated the effects of PTE on diabetic rats and clarified the underlying mechanism. Diabetes was induced in rats by streptozotocin (STZ) and a high-sugar and high-fat diet. Rats were then treated with PTE (20, 40 and 80 mg/kg/d) for 8 weeks. Oral glucose tolerance test (OGTT) was performed to measure the glycometabolism of the diabetic rats at the end of the treatment. Fasting blood glucose (FBG), fasting insulin (FINS) and lipid profile were determined using an automatic biochemistry analyzer and serum inflammatory factors were analyzed by enzyme-linked immunosorbent assay. Serum superoxide dismutase (SOD) and malondialdehyde (MDA) were also analyzed by spectrophotometry to evaluate the anti-oxidant effects. The expression of proteins of PPARγ and PI3K/Akt signaling pathway related proteins in adipose tissue of the diabetic rats was analyzed by Western blotting. PTE treatment significantly reduced weight loss, FBG, insulin resistance, serum lipid levels and inflammatory factors. PTE treatment also inhibited oxidative stress by decreasing MDA expression and increasing SOD expression. Simultaneously, PTE treatment significantly ameliorated morphological impairment of the pancreas in diabetic rats. Furthermore, PTE treatment significantly increased the protein expression of PPARγ, PI3K, p-Akt, GLUT4 and IRS-1 in adipose tissues of diabetic rats. This study suggests that PTE can exert antidiabetic effects via the PI3K/Akt signaling pathway.