Abstract： Objective To explore the effect of Tongluo Yishen Formula on renal fibrosis and piezo1 in rats with unilateral ureteral obstruction(UUO).Methods Using UUO rats as the model,Tongluo Yishen Formula as the intervention method,and valsartan as the positive control substance,the drug was administered continuously for 14 days,to observe the changes in blood creatinine and urea nitrogen in rats.The method of hematoxylin-eosin(HE)staining was used to observe the pathological and morphological changes of kidneys in rats.The method of type Ⅲ collagen immunohistochemistry were used to evaluate the degree of renal interstitial fibrosis in rats.Immunofluorescence was used to detect CD34 for observing the changes of peritubular capillry(PTC)in kidneys.The methods of immunohistochemistry,Western blot,and RT-PCR were used to observe the changes in mRNA and protein expression of piezo1 and its downstream molecules.Results Compared with the sham group,creatinine and urea nitrogen levels in the model group were increased in serum(P<0.05).Compared with the model group,the serum creatinine(P<0.05)and urea nitrogen(P>0.05)in the valsartan group and the Tongluo Yishen Formula group were decreased.Compared with the sham group,the model group showed significant changes in renal interstitial fibrosis under microscope,with a significant decrease in PTC and an increase in piezo1 expression.After intervention with Tongluo Yishen Formula and valsartan,the degree of renal interstitial fibrosis in UUO rats were improved,with an increase in PTC and a decrease in piezo1 expression.Compared with the sham group,the expression of piezo1 protein in the model group was significantly increased(P<0.05),and both Tongluo Yishen Formula and valsartan intervention could reduce the expression of piezo1 protein(P<0.05).Compared with the sham group,the expression of PlGF in the renal tissue of the model group rats were increased(P<0.05).Compared with the model group,the expression of PlGF in the valsartan group and the Tongluo Yishen Formula group were increased(P<0.05).The receptor flt1 expression of PlGF in the model group were decreased compared with the sham group(P<0.05),while the expression level of flt1 were increased in the valsartan group and the Tongluo Yishen Formula group compared with the model group.Conclusion Tongluo Yishen Formula can significantly improve the progression of renal interstitial fibrosis in UUO rats.Its mechanism may be related to downregulating the expression of piezo1 protein,upregulating the expression of ADM,PlGF and their receptors flt1,alleviating PTC damage,and antagonizing renal interstitial fibrosis.