SERUM ANTIOXIDANT STATUS IN STREPTOZOTOCIN-INDUCED DIABETIC RAT

To determine whether decrease in serum antioxidants contributes to the increased oxidative stress, we measured the antioxidant activity (AOA ), total peroxyl radical-trapping antioxidant parameter (TRAP), and th eir component individual antioxidants in the serum of diabetic rats. A OA was assayed as the ability of serum to inhibit lipid autoxidation i n brain homogenates. TRAP was assayed as the ability to delay lipid pe roxidation induced by an azo initiator. Antioxidants measured were cer uloplasmin, unsaturated iron binding capacity (UIBC) and albumin as co mponents of AOA; and uric acid, protein sulfhydryl and alpha-tocophero l as components of TRAP. AOA was decreased markedly in the diabetics d ue to the decrease in ceruloplasmin, UIBC and albumin. On the other ha nd, the directly measured TRAP in the diabetics was unaltered. Uric ac id and alpha-tocopherol were increased in the diabetics. However, decr ease in unidentified scavengers offset the increase brought about by t hose antioxidants. These results suggest that the decreased metal bind ing capacity contributes to the increased oxidative stress in the diab etic rats.