The male C57BL/6 mice (8 weeks old, 22-25 g body weight) used in this study were purchased from Dashuo Bio-Technique Co. Ltd. (Chengdu, China) and were maintained in 12 hr of light/12 hr of darkness. The mice were randomly divided into the following 4 groups (n = 8 per group): Sham, UUO, UUO with tectorigenin (20 mg/kg/day, dissolved in saline with 10% dimethyl sulfoxide [DMSO]) or irbesartan (IRB, a positive control, 20 mg/kg/day) treatment. After anesthesia with 1% pentobarbital, the left ureter was exposed through the lower left incision on the midline of the back and blocked by two-point ligation with 40 silk thread as previously described. The Sham-operated mice underwent the same operation but absence of ligation. The tectorigenin and IRB group were administered intraperitoneally with drug daily for 7 consecutive days since surgery. Sham-operated mice and UUO mice were received the equal volume of solvent.