Renoprotective potential of quercetin in experimental diabetic nephropathy: assesing antiapoptotic and antioxidant effects

Aim: We investigated renoprotective and anti-apoptotic effects of quercetin, a potent bioflavonoid, by evaluating expression of apoptosis-regulatory genes that contribute to the kidney damage caused by diabetes in rats. Methods: Rats were divided into 4 groups; Control, STZ-induced diabetic, STZ-induced diabetic+Quercetin and Quercetin control. Values of fasting blood glucose, body weight and urine microalbuminuria measured. Immunohistochemistry was performed using bax, bcl-2, caspase-3 antibodies. For apoptosis detection, TUNEL method was applied. Advanced oxidation protein products (AOPP), protein carbonyl oxidation (PCO), malondialdehyde (MDA) and superoxide dismutase (SOD) activity were measured in homogenized kidney tissues. Results: Blood glucose and microalbuminuria levels were significantly decreased in quercetin-treated diabetic group compared to the untreated-diabetic group (p=0.020 and p=0.003; respectively). MDA, AOPP and PCO levels were significantly decreased (p=0.001, p=0.0001 and p=0.0005; respectively); however, SOD activity were found to increase in quercetin-treated diabetic group (p=0.005). Immunostaining of bcl-2, bax and caspase-3 was decreased compared to the untreated-diabetic group. Apoptotic cells especially increased in the kidney tubuli of untreated-diabetic group and on the contrary, a significant decrease was observed in the group that received a quercetin treatment (p=0.0001). Conclusion: Our results revealed that antiapoptotic effects of quercetin, which has predominantly antioxidant effects, may be useful in reducing effects of diabetic complications and preventing new complications