Comparison of the effects of vitamin E and/or quercetin in attenuating chronic cyclosporine A-induced nephrotoxicity in male rats.

1. The aim of the present study was to investigate the effects of vitamin E and/or quercetin (Q) on renal function, oxygen radical concentrations in the kidney and some anti-oxidant enzyme activities in rats treated with cyclosporine A (CsA). 2. Groups of rats (270 +/- 15 g), on standard rat chow and water, received all their treatments by gavage for either 4 or 8 weeks. Control groups received either olive oil (0.5 mL) or 25% ethanol (0.5 mL) + olive oil (0.5 mL) per day as vehicle. All experimental groups received 25 mg CsA/kg per day in 0.5 mL olive oil. The vitamin E group received 100 mg vitamin E/kg per day in olive oil in addition to CsA treatment. The quercetin group received 15 mg of Q/kg per day in 0.5 mL of 25% ethanol in addition to CsA treatment. The vitamin E + quercetin group received the two anti-oxidants at the concentrations given in addition to CsA treatment. 3. Quercetin, at a concentration less than one-quarter of vitamin E, was more efficient in lowering blood urea nitrogen, serum creatinine and kidney malondialdehyde in CsA-treated rats. However, neither of the two anti-oxidants was able to normalize these analytes to control values after either 4 or 8 weeks treatment. 4. Quercetin (50 micromol/kg per day) elevated all renal anti-oxidant enzyme activities to values observed in the negative controls. However, vitamin E (232 micromol/kg per day) only normalized glutathione peroxidase activity at the end of either 4 or 8 weeks treatment. Combination treatment with the two anti-oxidants abolished all the ill-effects of CsA. 5. Combination treatment with the two anti-oxidants of renal transplant patients receiving CsA may be beneficial in ameliorating the chronic nephrotoxic effects of the important immunosuppressive drug CsA.