Quercetin protects against oxidative stress-related renal dysfunction by cadmium in rats

The aim of this study was to investigate the possible protective role of the dietary flavonoid quercetin on cadmium (Cd)-induced nephrotoxicity using biochemical and histopathological approaches. In experimental rats oral administration of CdCl₂ (5 mg/kg) for 4 weeks significantly induced renal damage which was evident from the increased levels of serum urea, uric acid and creatinine with a significant (p<0.05) decrease in creatinine clearance. Cd also significantly (p<0.05) decreased the levels of urea, uric acid and creatinine in urine. Cd-induced oxidative stress in kidney tissue was indicated by the increased levels of renal lipid peroxidation markers (thiobarbituric acid reactive substances and lipid hydroperoxides) and protein carbonyl content with a significant (p<0.05) decrease in non-enzymatic (total sulphydryl group, reduced glutathione, vitamin C and vitamin E) and enzymatic antioxidants (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR) and glucose 6-phosphate dehydrogenase (G6PD)). Moreover the kidneys of Cd-treated rats showed tubular necrosis, degeneration, dilation, desquamation, thickening of basement membrane and luminal cast formation. Quercetin treatment markedly attenuated the Cd-induced biochemical alterations in serum, urine and renal tissue. Quercetin also ameliorated the Cd-induced pathological changes when compared with Cd-alone-treated group. These data indicate that the natural dietary antioxidant quercetin might have protective effect against Cd-induced nephrotoxicity and oxidative stress in rats.