Effect of Long Term Supplementation of Vitamin E Attwo Different Doses on Lipid Peroxidation and Antioxidative Enzymes Activity During Aging in Rats

摘要

Vitamin E a biological lipid antioxidant has been reported to influence the aging process while antioxidative enzymes activity have been postulated to be affected with age. The aim of our study is to look at the changes in the Malondialdehyde (MDA) levels (the product of lipid peroxidation) in plasma and activities of erythrocyte antioxidative enzymes such as Glutathione Peroxidase (GPx), Catalase (Cat) and Superoxide Dismutase (SOD) in rats supplemented with two different doses of vitamin E during aging. Twenty-four Wistar rats aged 6 months, weighing 250-300 grams were divided into three groups. Control group was fed with basal diet, while treated groups were supplemented with -tocopherol at 60 and 120 mg kg 1 diet. The MDA levels and erythrocyte enzyme activities were determined every 10 weeks for 70 weeks. The results showed that MDA levels increased progressively until the rats were 16 months old (week 40) where it reached its peak value of 5.79?0.54 nmol mL-1. During subsequent 30 weeks, lower MDA levels were observed. This decrease in MDA levels was statistically significant compared to the peak value (p<0.05). In the treated groups, similar patterns were observed. However, the values attained were different. Rats supplemented with 60mg kg 1 diet of vitamin E had a significant lower peak value (5.53?0.49 nmol mL-1) compared to control. While those treated with 120 mg kg 1 diet of vitamin E attained a significantly higher peak value (7.72?0.43 nmol mL-1) as compared to control (p<0.05). GPx activity increased rapidly (p<0.05) until week 30 but subsequently the increase in activity was not as rapid. The group supplemented with 120-mg kg 1 diet showed a higher activity as compared to the lower dose and control group. Similarly, cat activity was found to decrease after 30 weeks, but supplementation with vitamin E did not cause significant changes in Cat activity compared to control group. Activity of SOD showed a different pattern, where its activity in control group peaked at week 40. Its activity initially reduced with vitamin E supplementation but increased significantly (p<0.05) after 40 weeks treatment. In conclusion, the study had shown that higher dose of vitamin E supplementation (120 mg kg 1 diet) generally increased the antioxidative enzymes as compared to the control however supplementation at lower dose (60mg kg 1 diet) reduced lipid peroxidation during aging in rats.