OBJECTIVETo observe the anti-renal fibrosis effect of Paidu Baoshen Pill (PBP) on 5/6 nephrectomized rats and to explore its mechanism.

METHODSTotally 50 SD male healthy rats were randomly divided into the normal control group (n = 10), the sham-operation group (n = 10), and the nephrectomy model group (n = 30) according to the proportion of 1:1:3. Rats in the sham-operation group had their renal capsule isolated without nephrectomy. Rats in the nephrectomy model group had their kidneys 5/6 nephrectomized. Then 24 h urine was collected and 24 h urinary protein (24 h UP) detected. Serum blood urea nitrogen (BUN) and serum creatitine (SCr) were also tested. According to the SCr level 30 rats of the model group were further randomly divided into the model group, the PBP group, and the Niaoduqing Granule (NG) group, 10 in each group. Rats in the PBP group and the NG group were respectively administered with PBP (at the daily dose of 1.0 g/kg) and NG (at the daily dose of 3.33 g/kg) by gastrogavage (they were dissolved in distilled water). At the same time, 2 mL distilled water was administered by gastrogavage to rats in the normal control group, the sham-operation group, and the nephrectomy model group, once daily for 4 successive weeks. Mental conditions, activities, hair color, shape of stool, and the body weight were observed during administration. After 4 weeks, urine was collected to detect 24 h UP. Blood was sampled to detect SCr, BUN, transforming growth factor β1 (TGF-β1), type III procollagen (PC III), collagen type IV (Col IV), laminin (LN), and fibronectin (FN). After rats were killed, their left remnant renal tissues were collected for pathological examinations. The protein expression quantity of TGF-β1 and FN was detected by immunohistochemical method. mRNA expression levels of TGF-β1 and FN were detected using real time fluorescent quantitative PCR.

RESULTSThere was no statistical difference in the above indices between the normal control group and the sham-operation group (P > 0.05). Compared with the sham-operation group, rats' general condition was poorer in the model group, their body weight grew slower, and 24 h UP increased; serum levels of BUN, SCr, TGF-β1, PC III, Col IV, LN, and FN increased; the residual renal pathological lesion was serious; expression levels of TGF-β1, TGF-β1, mRNA, FN, and FN mRNA increased in the renal tissue (all P < 0.01). Compared with the model group, rats' general condition was better, their body weight grew faster, 24 h UP reduced (P < 0.05), blood levels of BUN and SCr decreased significantly (P < 0.01), serum levels of TGF-β1, PC III, CoL IV, LN, and FN decreased (P < 0.05, P < 0.01); the residual renal pathological lesion was attenuated in the PBP group and the NG group; expression levels of TGF-β1, TGF-β1, mRNA, FN, and FN mRNA decreased (P < 0.01). Compared with the NG group, blood levels of SCr and FN, and expression levels of FN and FN mRNA decreased more in the PBP group (P < 0.05).

CONCLUSIONSPBP had the effect of anti-renal fibro- sis in 5/6 nephrectomized rats. Down-regulating expression levels of TGF-β1, and FN from gene transcription and protein translation levels might be one of its mechanisms.