α‐Tocopherol and α‐Lipoic Acid Enhance the Erythrocyte Antioxidant Defence in Cyclosporine A‐Treated Rats

The aim of this study was to determine the effects of dietary antioxidant supplementation with alpha-tocopherol and alpha-lipoic acid on cyclosporine A (cyclosporine)-induced alterations to erythrocyte and plasma redox balance. Rats were randomly assigned to either control, antioxidant (alpha-tocopherol 1000 IU/kg diet and alpha-lipoic acid 1.6 g/kg diet), cyclosporine (25 mg/kg/day), or cyclosporine + antioxidant treatments. Cyclosporine was administered for 7 days after an 8 week feeding period. Plasma was analysed for alpha-tocopherol, total antioxidant capacity, malondialdehyde, and creatinine. Erythrocytes were analysed for glutathione, methaemoglobin, superoxide dismutase, catalase, glutathione peroxidase, glucose-6-phosphate dehydrogenase, alpha-tocopherol and malondialdehye. Cyclosporine administration caused a significant decrease in superoxide dismutase activity (P<0.05 control versus cyclosporine) and this was improved by antioxidant supplementation (P<0.05 cyclosporine versus cyclosporine + antioxidant; P<0.05 control versus cyclosporine + antioxidant). Animals receiving cyclosporine and antioxidants showed significantly increased (P<0.05) catalase activity compared to both groups not receiving cyclosporine. Cyclosporine administration induced significant increases in plasma malondialdehyde and creatinine concentration (P<0.05 control versus cyclosporine). Antioxidant supplementation prevented the cyclosporine induced increase in plasma creatinine (P<0.05 cyclosporine versus cyclosporine + antioxidant; P>0.05 control versus cyclosporine + antioxidant), however, supplementation did not alter the cyclosporine induced increase in plasma malondialdehyde concentration (P>0.05 cyclosporine versus cyclosporine + antioxidant). Antioxidant supplementation resulted in significant increases (P<0.05) in plasma and erythrocyte alpha-tocopherol in both of the supplemented groups compared to non-supplemented groups. In conclusion, dietary supplementation with alpha-tocopherol and alpha-lipoic acid enhanced the erythrocyte antioxidant defence and reduced nephrotoxicity in cyclosporine treated animals.