Abstract: 【Abstract】Objective To investigate the effect and mechanism of the short peptide acetyl-Ser-Asp-Lys-Pro (AcSDKP) on renal interstitial fibrosis induced by unilateral ureteral obstruction in rats. Methods Thirty-six male Wistar rats were randomly divided into sham-operation group, unilateral ureteral obstruction (UUO) group, and UUO+AcSDKP treatment group. Animal model of rat renal interstitial fibrosis was established by unilateral ureteral ligation. Rats were sacrificed after the surgery for 3 or 14 days. Histological change of the obstructed kidney was observed by H-E staining. The protein expression and localization of transforming growth factor β1 (TGF-β1) and -smooth muscle actin ( -SMA) in renal tissues were detected by immunohistochemistry. The mRNA levels of TGF-β1 and -SMA were measured by reverse transcription- polymerase chain reaction. Results Compared with sham-operated group, rats in UUO group exhibited severe renal interstitial fibrosis and higher expression of TGF-β1 and -SMA (P＜0.05), while those in UUO+AcSDKP group demonstrated less renal interstitial fibrosis, and lower expression levels of TGF-β1 and -SMA (P＜0.05). Conclusions AcSDKP treatment improves renal interstitial fibrosis in rats by down-regulating TGF-β1 and -SMA expression.

Key words: Renal interstitial fibrosis, Transforming growth factor β1