| Diabetes is a group of endocrinological metabolic diseases whose etiology and pathogenesis have not yet been fully understood, expressed as glucose, lipids and protein metabolism disorders and secondary water, electrolyte imbalance, which led to a series of complications. Large number of studies show that the occurrence and development of diabetes are closely related to obesity, in vivo oxidation and antioxidant level changes and magnesium deficiency. Previous studies showed that supplement of vitamin E (VE) or magnesium had benificial effects on diabetes, but no documents reported the impacts of prophylactic supplementation of VE or/and magnesium on metabolism of glucose and lipids, especially insulin signaling pathway markers in diabetes while the high risk of diabetes happened at the same time. This study is a new finding to previous studies and the aims are to observe the effects of preventive treatment of VE or/and magnesium on glucose and lipid metabolism, the insulin signaling pathway molecules in high fat and high glucose diet and streptozotocin-induced diabetic rats.Wistar rats were randomly assigned to six groups, all fed with high fat and glucose diets plus either 0.5 g/kg diet vitamin E (group E), 0.6 g/kg diet magnesium (group MM), 1.2 g/kg diet magnesium (group HM), 0.5 g/kg diet vitamin E plus 0.6 g/kg diet magnesium (group EMM), 0.5 g/kg diet vitamin E plus 1.2 g/kg diet magnesium (group EHM), or no supplement (group C). Four weeks treatment of different diets and an overnight empty stomach later, all rats were injected streptozotocin to provoke diabetes mellitus. The whole trial lasted eight weeks. Malondialdehyde (MDA) level, superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) activities were detected using enzyme-biochamical methods. Lymphocytes proliferative capacity was evaluated by MTT assay. Hemolytic degree of red blood cell were detected using hemolysis test. Total plasma cholesterol (TC), triglycerides, high density lipoprotein (HDL), and low density lipoprotein (LDL) were measured by automatic biochemistry analyzer. Blood viscosity was measured using cone viscometer. Histological changes of liver was examined by hematoxylin & eosin stain. mRNA expressions of insulin receptor and glucose transporter-4 (GLUT-4) of skeletal muscle were determined using quantitive real-time PCR. Insulin receptor substrate-1 (IRS-1) was detected by immunohistological method. Protein expression of AMP-activated protein kinase-α2 (AMPK-α2) was estimate by western blot. The serum concentration of insulin, interleukin-6 (IL-6), and tumor necrosis factor-α(TNF-α) were detected by radioimmunoassay; insulin resistance index was calculated by formula.Compared with C group, insulin resistance index wad inhibited in E, MM, EMM, EHM group, the decrease was 5.52 (P<0.05), 2.28, 3.29, and 2.65 respectively. The insulin level decreased in all treated group, and the best effect was found in EMM group (P<0.01). No statistical difference was observed in fasting blood glucose in each treated group compared with control group. Compared with 7.79 mmol/L of TC in control group, the decrease of each treated group was 4.72 mmol/L (P=0.004); 3.54 mmol/L (P=0.062); 1.36 mmol/L (P=0.436); 3.75 mmol/L (P=0.016); 3.49 mmol/L (P=0.050) in E, MM, HM, EMM, and EHM group, respectively. Compared with C group, the differences of middle and high shear rates blood viscosity were lower in each treated groups (all P <0.001); but no significant changes were observed in low shear rate blood viscosity. Liver index in E group descended (P=0.034) while thymus index decreased in M and EM group (P=0.045, 0.035 respectively) compared with C group; no significant changes were founded in heart and spleen index. For histological changes of liver, hepatocytes were tumescent and filled with fat vacuole of inequality of size. The cell nuclei was pulled to the side by fat vacuole, and fatty infiltration was seen in the liver as a whole in control group. Prophylactic treatment of VE and magnesium could improve this status and the helpful effect in combined use of VE and magnesium was better than VE or magnesium supplementation alone. Prophylactic supplementation of VE or VE combined magnesium could attenuate the MDA level in liver, the decrease in E, EMM, and EHM group was 8.98 (P<0.01), 7.84 (P<0.05), and 7.56 (P<0.05) respectively. No benifical effect on MDA was observed in respective supplementation of magnesium alone. The activity of GSH-PX elevated in HM, EMM, and EHM group (P<0.05). SOD activity elevated in each treated group(all P<0.05). No statistical difference was observed on lymphocyte proliferation capacity between control group and each treated group. Preventive supplementation of VE or/and magnesium attenuated hemolytic degree of red blood cell greatly (all P <0.05), the decrease in each group was:E, 0.19 (P=0.003); MM, 0.22 (P=0.001); HM, 0.17 (P=0.030); EMM, 0.25 (P=0.001); and EHM, 0.25 (P=0.001), respectively. The mRNA expression of insulin receptor and GLUT-4 in E, MM, HM, EMM and EHM diet increased (all P<0.05). IRS-1 elevated 1.30 in EMM group (P=0.006), although elevation were observed in other treated groups, but no significant differences were observed compared with control group. Protein expression of AMPK-α2 increased in all treated group (P<0.01), and the best effect was supposed in EMM group (P<0.001). No significant difference were found in serum level of IL-6 and TNF-αin five treated group compared with control group. Statistical analysis showed there was no interaction between VE and magnesium.In conclusion, the present study, at the first time, suggests that a preventive supplementation of VE or/and magnesium are beneficial to improve pathologic status of inslin resistance and lipid metabolism, the mechanism may be related to the inhibition of lipid peroxidation, increase of antioxidative level and up-regulation of insulin signaling pathway markers. The best effects were found in EMM group. This study provides a experimental basis for the preventive application of VE combined magnesium in crowd in the future.
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