Resveratrol, a polyphenolic phytoalexin protects against cyclosporine-induced nephrotoxicity through nitric oxide dependent mechanism.

Cyclosporine A (CsA) is a potent and effective immunosuppressive agent, but its use is frequently accompanied by severe renal toxicity. The causes for the nephrotoxicity of CsA have not been fully elucidated. Intrarenal vasoconstriction induced by several different mediators, both in humans and experimental animals have been proposed. The present study was designed to investigate the possible protective effect of resveratrol on CsA-induced nephrotoxicity and to explore the possible mechanism involved in resveratrol's effect. Eight groups of rats were employed in this study, group 1 served as control, group 2 rats were treated with olive oil (vehicle for CsA), group 3 rats were treated with CsA (20 mg/kg, s.c. for 21 days), groups 4, 5 and 6 received CsA along with resveratrol (2, 5 and 10 mg/kg, p.o. 24 h before and 21 days concurrently), respectively, group 7 rats were treated with NOS inhibitor, L-NAME (10 mg/kg) along with resveratrol and CsA and group 8 rats received L-NAME along with CsA. CsA administration for 21 days resulted in a marked renal oxidative stress, significantly deranged the renal functions, reduced the tissue and urine nitrite levels and markedly altered the renal morphology. Treatment with resveratrol (5 and 10 mg/kg) significantly improved the renal dysfunction; tissue and urine total nitric oxide levels, renal oxidative stress and prevented the alterations in renal morphology. Concurrent administration of L-NAME blocked the protective effect of resveratrol indicating that resveratrol exerts its protective effect by releasing nitric oxide. These results clearly demonstrate the pivotal role of nitric oxide in etiology of CsA nephrotoxicity and indicate the renoprotective potential of resveratrol in CsA nephrotoxicity.