Objective: To investigate the effect of Kudiezi injection on renal tubulointerstitial fibrosis and the possible mechanisms. Method: Unilateral ureteral ligation was used to establish renal interstitial fibrosis models

and the Sprague-dawley rats were randomly divided into normal group

sham operation group

model group

valsartan (0.01 g · kg-1) group

Kudiezi low and high (0.15

0.30 g · kg-1) dose groups.At 7th and 14th day after the administration

the rats were sacrificed for blood samples and renal tissues.Serum creatinine (SCr) and blood urea nitrogen (BUN) levels were measured for renal function. Malondialdehyde(MDA) content and superoxide dismutase(SOD) activity were measured to reflect renal oxidative stress levels.Hematoxylin eosin(HE) and Masson staining were used to visualize renal fibrosis in each group. Immunohistochemical analysis was used to detect the expression of transforming growth factor-β1(TGF-β1)

phosphorylated-Smad2/3 (p-Smad2/3)

and bone morphogenetic protein-7(BMP-7). The expression levels of TGF-β1

Smad2

Smad3

BMP-7 and type I collagen(ColⅠ) mRNA in renal tissue were detected by reverse trconscription polymerase chain reaction (RT-PCR). Result: Kudiezi could decrease the level of serum creatinine in renal interstitial fibrosis rats

alleviate tubulointerstitial damage

reduce the relative area of renal interstitial collagen

down-regulate the content of MDA andthe expression of TGF-β1

p-Smad2/3

Col Ⅰ

and up-regulate the activity of SOD and the expression of BMP-7.As compared with Kudiezi low dose group

Kudiezi high dose (0.30 g · kg-1) group showed better effect and the difference was statistically significant (P<0.05). Conclusion: The protective effect of Kudiezi on renal interstitial fibrosis in rats might be related to the reduction of oxidative stress level and inhibition of TGF-β1/Smad/BMP-7 signaling pathway

thereby inhibiting the proliferation of extracellular matrix.