Beneficial effects of selected antioxdants in experimental diabetes
AbstractThe antioxidant effects of Vitamins C, E and N-acetyl-L-cysteine (N) on glucose disposal, reduced glutathione (GSH), malonyldialdehyde (MDA) and antioxidant enzymes glutathione peroxidase (GPX) and glutathione reductase (GRT) in the levels of streptozotocin-induced diabetic rats was investigated.
Glucose tolerance test (GTT) levels of untreated rats (group 1) were relatively elevated in STZ rats compared with rats fed antioxidant, supplemented diets, (Vit. C + E, group 3) and (N+C+E, group 4), although both antioxidant supplemented and untreated rats did not dispose off any appreciable quantity of glucose. A significant level (P<0.05) of GSH increase occurred in the red blood cells (RBCs) of diabetic rats on antioxidant supplement as compared with untreated diabetic rats. In contrast untreated diabetic rats (group 1) had significantly higher (P<0.05) MDA values of RBCs as compared with diabetic rats on supplementation of antioxidants (groups 2-4). The results of diabetic control rats showed that the concentrations of GSH-Px and GRT were increased as opposed to decreases in GSH levels suggesting that GSH regeneration by oxidized glutathione (GSSG) and the generation of NADP+ from NADPH is theoretically insufficient under diabetic conditions.
This study therefore demonstrates that the levels of membrane lipid peroxidation in antioxidant supplemented diabetic rats RBC may have been blocked by vitamins C and E and by the replenishment of cellular GSH by N-acetyl-L-cysteine (N).
KEY WORDS: Lipid peroxidation, antioxidants, diabetes mellitus.
Global Jnl of Pure and Applied Sciences Vol.10(4) 2004: 563-566