Rutin ameliorates renal fibrosis and proteinuria in 5/6-nephrectomized rats by anti-oxidation and inhibiting activation of TGFβ1-smad signaling.

OBJECTIVES Rutin, a polyphenolic flavonoid, was reported to have beneficial effect on drug induced nephropathy. The present study aimed to introduce 5/6 nephrectomized rat model to further evaluate its renal protective effect. METHODS Adult Wistar rats were induced to develop chronic renal failure through 5/6 nephrectomy (5/6 Nx). After that, animals were treated orally with saline, rutin at 15 and 45 mg/kg, and losartan (10 mg/kg) daily for 20 weeks; sham-operated animals were also involved as control. After treatment for 8 and 20 weeks, blood and urine samples were collected for biochemical examination; all the kidney remnants were collected for histological examination. The protein levels of TGF-β1, smad2 and phosphorylated-smad2 (p-smad2) in kidney were measured. Immunohistochemistry was used to analyze the expression of TGF-β1, fibronectin and collagen IV in kidney tissues. RESULTS Results suggested that rutin could reduce the proteinurea, blood urine nitrogen and blood creatinine in 5/6 Nx animals significantly, as well as oxidation stress in the kidney. By histological examination, rutin administration alleviated glomerular sclerosis scores and tubulointerstitial injuries in a dose-dependent manner (P<0.01). Immunohistochemistry also suggested rutin could reduce the expression of TGF-β1, fibronectin and collagen IV in kidney tissues. By western blot, we found the rutin could reduce the TGF-β1, p-smad2 expression in the kidney tissues of rats. CONCLUSIONS This study suggests that the rutin can improve renal function in 5/6 Nx rats effectively. Its effect may be due to its anti-oxidation and inhibiting TGFβ1-Smad signaling.