title: Effects of vitamin E supplementation on oxidative stress in streptozotocin induced diabetic rats: investigation of liver and plasma.
abstract: This experimental study was designed to investigate the effects of vitamin E supplementation, especially on lipid peroxidation and antioxidant status elements 3/4 namely, glutathione (GSH), CuZn superoxide dismutase (CuZn SOD), and glutathione peroxidase (GSH Px), both in blood and liver tissues of streptozotocin (STZ) diabetic rats. The extent to which blood can be used to reflect the oxidative stress of the liver is also investigated. In diabetic rats, plasma lipid peroxide values were not significantly different,from control,whereas erythrocyte CuZn SOD (p < 0.01), GSH Px (p < 0.001) activities and plasma vitamin E levels (p < 0.001), were significantly more elevated than controls. Vitamin E supplementation caused significant decreases of erythrocyte GSH level (p < 0.01) in control rats and of erythrocyte GSH Px activity (p < 0.05) in diabetic rats. Liver findings revealed significantly higher lipid peroxide (p < 0.001) and vitamin E (p < 0.01) levels and lower GSH (p < 0.001), CuZn SOD (p < 0.001) and GSH Px (p < 0.01) levels in diabetic rats. A decreased hepatic lipid peroxide level (p < 0.01) and increased vitamin E/lipid peroxide ratio (p < 0.001) were observed in vitamin E supplemented, diabetic rats. A vitamin E supplementation level which did not cause any increase in the concentration of the vitamin in the liver or blood, was sufficient to lower lipid peroxidation in the liver. Vitamin E/lipid peroxide ratio is suggested as an appropriate index to evaluate the efficiency of vitamin E activity,independent of tissue lipid values. Further, the antioxidant components GSH, GSH Px and CuZn SOD and the relationships among them, were affected differently in the liver and blood by diabetes or vitamin E supplementation.
authors.affiliation: Department of Biochemistry, Istanbul University Cerrahpaa Medical Faculty, Turkey. bbseven@superonline.com
authors.forename: Arzu
authors.initials: A
authors.lastname: Seven
authors.forename: Sava
authors.initials: S
authors.lastname: Guzel
authors.forename: Oktay
authors.initials: O
authors.lastname: Seymen
authors.forename: Sabiha
authors.initials: S
authors.lastname: Civelek
authors.forename: Murat
authors.initials: M
authors.lastname: Bolayirli
authors.forename: Murat
authors.initials: M
authors.lastname: Uncu
authors.forename: Gulden
authors.initials: G
authors.lastname: Burcak
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D005978:Glutathione / Q000097:blood; D005979:Glutathione Peroxidase / Q000097:blood; D015227:Lipid Peroxidation / Q000187:drug effects; D008099:Liver / Q000378:metabolism*; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D013482:Superoxide Dismutase / Q000097:blood; D014810:Vitamin E / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D014810:Vitamin E; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D005978:Glutathione