Antioxidant effects of alpha tocopherol, ascorbic acid and L-methionine onlead induced oxidative stress to the liver, kidney and brain in rats

Lead exposure related oxidative stress has been incriminated, at least in p art. to its toxic effects in different organs. The present investigation wa s carried out to study the ameliorative effects of antioxidant (ascorbic ac id, alpha tocopherol or L-methionine) alone and antioxidant (alpha tocopher ol) plus a conventional chelator (CaNa2 EDTA) on some of the parameters ind icative of oxidative stress in the liver, kidney and brain in lead-exposed rats. Rats were given 0 (n = 6. healthy controls) or 1 mg of Pb-2 +/kg b.w (n = 30) as lead acetate solution in sterile normal saline ip for a period of 4 weeks. The ip injections were then withdrawn and lead exposed rats wer e randomly divided into five equal groups. six lead-exposed rats were given no treatment during the 5th week (Pb group) to serve as positive controls. The rest four groups received either ascorbic acid, alpha tocopherol or L- methionine in the 5th week at the daily dose of 100 mg/kg b.w orally or alp ha tocopherol as above plus CaNa2 EDTA at the rate of 110 mg/kg b.w twice a day ip for a period of 4 days. All the animals were sacrificed 1 day after the end of the experiment, and the liver, kidney and brain were quickly ex cised For the estimation of lead burden and alteration in the oxidative ind ices. Lead exposure for a period of 4 weeks followed by a period or 1 week to recover. resulted in significantly (P < 0.05) higher accumulation of lea d, associated with significant (P < 0.05) increases in lipid peroxide level in the liver and brain, and non-protein bound thiol contents in the brain. Changes in the superoxide dismutase and catalase activities in lead-expose d rats did not reach statistical (P < 0.05) significance. Treatment with an tioxidants alone resulted in reversal of oxidative stress without significa nt decline in tissue lead burden. Tissue specific changes, following lead e xposure and responses to the treatment with different antioxidants were rec orded in the parameters of oxidative damage viz. lipid peroxide level, anti oxidant enzymes and thiol contents. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.