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Abstract
This study determined the effects of α- and γ-tocopherol supplementation on metabolic control and oxidative stress in type 2 diabetic Otsuka Long–Evans Tokushima Fatty (OLETF) rats. Blood glucose, haemoglobin A1c (HbA1c), urinary protein, plasma free fatty acid, triacylglycerol and plasminogen activator inhibitor-1 (PAI-1) levels in OLETF rats were significantly higher than in non-diabetic control Long–Evans Tokushima Otsuka (LETO) rats. α-Tocopherol inhibited the increase in urinary protein, blood glucose, HbA1c and PAI-1 levels, but γ-tocopherol did not. Plasma and hepatic lipid peroxidation and hepatic steatosis were increased in OLETF rats. α-Tocopherol decreased lipid peroxidation. Mitochondrial reactive oxygen species production and uncoupling protein 2 (UCP2) expression were significantly increased in the heart and aorta of OLETF rats compared with LETO rats. Endothelial NO synthase and aortic nitrotyrosine were increased in OLETF rats. In contrast, the expression of phosphorylated vasodilator-stimulated phosphoprotein and glucose transporter 4 in the aorta was significantly decreased in OLETF rats. These abnormalities were reversed by α-tocopherol. These findings suggest that α-tocopherol may prevent cardiovascular tissues from oxidative stress and insulin signalling disorder resulting from diabetes mellitus.
| Abbreviations | ||
| COX | = | cytochrome oxidase |
| eNOS | = | endothelial NO synthase |
| FFA | = | free fatty acid |
| GLUT | = | glucose transporter |
| LETO | = | Long-Evans Tokushima Otsuka |
| OLETF | = | Otsuka-Long Evans Tokushima Fatty |
| pVASP | = | phosphorylated vasodilator-stimulated phosphoprotein |
| PAI-1 | = | plasminogen activator inhibitor-1 |
| ROS | = | reactive oxygen species |
| SOD | = | superoxide dismutase |
| UCP2 | = | Uncoupling protein 2. |
| Abbreviations | ||
| COX | = | cytochrome oxidase |
| eNOS | = | endothelial NO synthase |
| FFA | = | free fatty acid |
| GLUT | = | glucose transporter |
| LETO | = | Long-Evans Tokushima Otsuka |
| OLETF | = | Otsuka-Long Evans Tokushima Fatty |
| pVASP | = | phosphorylated vasodilator-stimulated phosphoprotein |
| PAI-1 | = | plasminogen activator inhibitor-1 |
| ROS | = | reactive oxygen species |
| SOD | = | superoxide dismutase |
| UCP2 | = | Uncoupling protein 2. |