The Effect Of NO-1886 On Insulin Resistance-associated Factors In Type 2 Diabetic Minipig Model

Background and the aimInsulin resistance (IR) is a common feature and a contributing factor to T2DM. It is significant to develop potential drugs for reducing IR to the prevention and treatment T2DM. The novel compound NO-1886, an activator to lipoprotein lipase (LPL), has been proven to be highly effective in improving the chronic metabolic disorders of lipid and glucose, and in alleviating insulin resistance. However, the mechanism of NO-1886 on IR has not been elucidated. The aim of this study was to investigate the effects of NO-1886 on insulin resistance-associated factors such as glycogen synthase kinase-3 (GSK-3β), glucose transporter protein-4 (GLUT-4) and tumor necrosis factor-α(TNF-α) in type 2 diabetic minipig model induced by a high-fat/high-sucrose/high-cholesterol diet (HFSCD), and to explore the potential mechanisms of NO-1886 alleviating IR.Materials and methods1) Animal experiment. Fifteen male Guangxi Bama miniature pigs were randomized into three groups with similar body weight (5 in each) and fed with a control diet (CD) or high-fat/high-sucrose/high-cholesterol diet (HFSCD) or HFSCD supplemented with 1.0% NO-1886 (HFSCD+NO-1886) for 5 months. 2) Plasma biochemical assays. Fasting plasma glucose, insulin, triglyceride (TG) and free fatty acid(FFA) were measured at the end of each month. Insulin resistance and beta-cell function were estimated by oral glucose tolerant test (OGTT) at monthly intervals and insulin sensitive test at month 5. 3) Histopathology. Four-Λm-thick sections were prepared and routinely stained with hematoxylin and eosin (H&E) to examine the general histological changes in the cardiac muscle, skeletal muscle, liver, pancreas and kidney tissue, and periodic acid-Schiff (PAS) to identify changes in glycogen deposition in hepatic tissue. 4) The mRNA expression of GSK-3βand TNF-αin the kidney and liver were measured by real time PCR. 5) The protein expression of GSK-3β, GLUT-4, TNF-αwere measured by Western Blot and immunohistochemistry in the cardiac muscle, skeletal muscle, liver and kidney.Results The high-fat/high-sucrose/high-cholesterol diet induced Guangxi Bama-miniature pigs to appear glucose and lipid metabolic disorders including hyperglycemia, hyperinsulinemia and hyperlipoidemia, and pathological changes in these tissues, and reduced glycogen deposition in hepatic tissue. Moreover, HFSCD markedly increased the mRNA and protein expression of GSK-3βand TNF-αin the cardiac muscle, skeletal muscle, liver and kidney, and decreased the protein expression of GLUT-4 in the cardiac muscle and skeletal muscle compared with CD group. NO-1886 improved disorders of glucose and lipid metabolism and alleviated insulin resistance in minipig induced by HFSCD. NO-1886 decreased the mRNA and protein expression of GSK-3βand TNF-α, and increased the protein expression of GLUT-4 compared with HFSCD group.Conclusion1. NO-1886 improves disorders of glucose and lipid metabolism by reducing plasma glucose, insulin, TG and FFA level, and alleviates insulin resistance in type 2 diabetic minipig induced by high-fat/high-sucrose/high-cholesterol diet.2. High-fat/high-sucrose/high-cholesterol diet increases the mRNA and protein expression of GSK-3β, TNF-αin the cardiac muscle, liver, skeletal muscle and kidney whereas NO-1886 down-regulates the expression of GSK-3βand TNF-α, alleviates insulin resistance. 3. High-fat/high-sucrose/high-cholesterol diet decreases the protein expression of GLUT-4 in the cardiac muscle and skeletal muscle whereas NO-1886 up-regulates the expression of GLUT-4, alleviates insulin resistance. .