Influence of defatted flaxseed diet on insulin sensitivity, vascular permeability and lipid profile in a rat model of type 2 diabetes mellitus

Abstract

The impact of flaxseed (FSD) intake, a rich source of alpha linolenic acid (ALA), fiber and lignans, on the cardiovascular system is well documented. However, mechanisms by which flaxseed improve cardiovascular health are not clear. The aim of this study was to investigate the effects of dietary flaxseed on vascular permeability and endothelial function in streptozotocin-induced type 2 diabetes in rats. Type 2 diabetes mellitus (T2DM) was induced in male Sprague-Dawley rats by intraperitoneal injection of streptozotocin (35 mg/kg body weight) after short term feeding of high fructose diet. Diabetic rats were divided into three groups, one group fed standard diet, second group fed standard diet supplemented with defatted flaxseed powder (FSD), and third group received Metformin (200 mg/kg BW (body weight)) for 8 weeks. Fasting serum concentrations of glucose (FPG), insulin, vascular endothelial growth factor (VEGF), nitric oxide (NO), uric acid (UA) and lipid profile were measured. Vascular permeability index (VPI) was assessed at the end of experiment by quantifying the extravasation of albumin-bound Evans blue (EB) dye in the heart. Dietary FSD supplementation is comparable to Metformin in modulating blood lipid profiles, insulin and FPG levels. FSD intake was associated with significant reductions in serum insulin (-66%), glucose (-68%), VEGF levels (-66.8%) and UA (-63%), and NO (-37.5%) as compared to diabetic group without FSD supplementation. There were also improvements in lipid profile, vascular permeability index (VPI), insulin resistance and atherogenic indices in diabetic rats supplemented with flaxseed. These results suggest that dietary FSD supplementation may reduce the incidence of diabetic vascular complications through improvement of insulin sensitivity, vascular permeability and lipid profile. Key words: Diabetes mellitus, cardiovascular diseases, vascular permeability, endothelial dysfunction, insulin resistance, vascular endothelial growth factor, nitric oxide.