Hypoglycemic effects of wheat bran alkyresorcinols in high-fat/high-sucrose diet and low-dose streptozotocin-induced type 2 diabetic male mice and protection of pancreatic β cells

Abstract

In the present study, the hypoglycemic effects of wheat bran alkyresorcinols (ARs) were investigated in type 2 diabetes mellitus (T2DM) mice induced by a high-fat/high-sucrose diet (HFSD) combined with low dose streptozotocin (STZ). After the consumption of 5 mg kg⁻¹ d⁻¹ acarbose (positive control) and different doses of wheat bran ARs (50, 200 and 500 mg kg⁻¹ d⁻¹) for 4 weeks, the fasting blood glucose (FBG) levels in T2DM mice were found to be reduced significantly (p < 0.05), and the effects of 200 and 500 mg kg⁻¹ d⁻¹ administration were better than that of 50 mg kg⁻¹ d⁻¹. The results of the oral glucose tolerance test (OGTT) also showed that both acarbose and AR administration significantly increased the glucose tolerance of the T2DM mice. Then, the fasting serum insulin levels (FINS) were significantly reduced by AR treatment, and the effect of 500 mg kg⁻¹ d⁻¹ AR administration was better than that of 5 mg kg⁻¹ d⁻¹ acarbose. The profile of plasma lipids was analyzed simultaneously, and the results showed that the contents of total cholesterol (TC), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-C) were significantly decreased, while the content of high-density lipoprotein cholesterol (HDL-C) was increased significantly after 200 and 500 mg kg⁻¹ d⁻¹ AR treatment (p < 0.05). Furthermore, 200 and 500 mg kg⁻¹ d⁻¹ ARs significantly increased the content of hepatic glycogen and the activity of glucokinase (p < 0.01) in T2DM mice. The relative mRNA levels of glucose transporter 2 (GLUT2) in the liver tissue were increased markedly in 200 and 500 mg kg⁻¹ d⁻¹ AR treatment groups (p < 0.01), and the relative mRNA levels of glucose transporter 4 (GLUT4) in the epididymal adipose tissue were increased significantly in all AR treatment groups, especially significantly higher than acarbose (p < 0.01). Histological analyses revealed that treatment with ARs exerted a protective role on pancreatic β-cells. The results indicated that ARs could be an effective hypoglycemic active ingredient in whole grain diets.