$\omega-6$ 다중불포화지방을 섭취한 백서에서 비타민 E보충이 인슐린저항성과 산화적 스트레스에 미치는 영향

The Effect of Vitamin E Supplementation on Insulin Resistance and Oxidative Stress in Sprague Dawley Rats Fed High $\omega-6$ Polyunsaturated Fat Diet

Background : Excessive intakes of $\omega$6 polyunsaturated fatty acid (PUFA) can increase oxidative stress, which may increase insulin resistance and could be the cause of metabolic syndrome X such as diabetes mellitus. One of the ways to reduce oxidative stress is the consumption of antioxidants such as vitamin E. It is controversial that vitamin E intakes may alleviate insulin resistance. The purpose of the study was whether high vitamin E intake may influence whole body glucose disposal rate(GDR), glycogen deposites, triglyceride content, lipid peroxide levels and antioxidant enzyme activities in Sprague Dawley rats fed high $\omega$6 PUFA diest. Methods : Sprague Dawley rats were divided into three groups. The control group consumed chow diet. High and low vitamin E groups consumed 40% PUFA of total energy intakes. One kilogram of diet mixture contained 300IU of $\alpha$-tocopherol in high vitamin E group, while it had 30 IU in low vitamin E group. Diets were given for 8 weeks. After 7 were of diet consumption, indwelling catheters were inserted in carotid artery and jugular vein of all rats so that GDR could be measured in awake and unstressed state. Results : Daily PUFA intakes were lower in the control group than others. Daily vitamin E intake of high vitamin E group was about ten times higher than those of low vitamin E group and the control group(p<0.0001). $\alpha$-tocopherol content in lier was highest in the high vitamin E group. GDR of the control group was 24% higher than others, and vitamin E intakes did not affect GDR. Glycogen deposit of liver in the control group was significantly higher than others, and it was not altered by vitamin E supplementation. Muscle glycogne content showed a similar tendency as liver glycogen in different diet groups. Triglyceride deposit in muscle was not different among groups. Lipid peroxide content of liver in the high vitamin E group was lower than the low of glutathione peroxidase were lowered in low vitamin E group than others, however, those of superoxide dismutase and catalase were not different. Conclusions : High vitamin E intakes can decrease oxidative stress in rats fed high (())-6 PUFA diet, but they cannot alleviate insulin resistance. Thus, increased oxidative stress through high (())-6 PUFA diet may be minimal for influencing insulin resistance.