Abstract:Objective To investigate the regulatory effect of Qizhen Jiangtang Granule on the TGF-β1/Smad signaling pathway in rats with diabetic nephropathy and its mechanism of action in improving diabetic nephropathy. Methods A rat model of type 2 diabetic nephropathy was established by high-fat diet combined with intraperitoneal injection of streptozotocin, and after successful modeling, the rats were randomly divided into model group, metformin group, and low-, middle-, and high-dose Qizhen Jiangtang Granule groups, with 10 rats in each group. Another 10 normal rats were enrolled as normal control group. The drugs were given by gavage for 8 weeks, and then the levels of urinary α1 microglobulin, β2 microglobulin, and albumin. HE staining was used to observe the degree of renal tissue damage, and immunofluorescent staining was used to observe the expression of transforming growth factor beta 1 (TGF-β1) and transforming growth factor beta type Ⅰ receptor (TGF-βRⅠ) in renal tissue. RT-PCR was used to measure the mRNA expression of TGF-β1, TGF-βRⅠ, Smad3, and Smad7 in renal tissue, and Western blot was used to measure the protein expression of TGF-β1, TGF-βRⅠ, Smad3, p-Smad3, Smad7, and p-Smad7 in renal tissue. Results Compared with the normal control group, the model group had significant increases in the levels of urinary α1 microglobulin, β2 microglobulin, and albumin (P<0.05), marked renal tissue damage, and increases in the expression of TGF-β1 and TGF-βRⅠ, as well as significant increases in the mRNA expression of TGF-β1, TGF-βRⅠ, and Smad3 and the protein expression of TGF-β1, TGF-βRⅠ, Smad3, and p-Smad3 (P<0.05) and significant reductions in the mRNA expression of Smad7 and the protein expression of Smad7 and p-Smad7 (P<0.05). Compared with the model group, the Qizhen Jiangtang Granule groups had varying degrees of reversal in the above indices (P<0.05). Conclusion To a certain degree, Qizhen Jiangtang Granule can improve the degree of renal tissue damage in rats with diabetes, possibly by regulating the protein expression of the TGF-β1/Smad signaling pathway.