OBJECTIVETo explore whether there is phenotypic modulation of mesangial cells in streptozotocin (STZ) induced diabetic rats and study the effect of Tujian Mixture (TJM) on it.

METHODSSD rats were divided into the normal control group (NC group, n = 8), the unilateral nephrectomized control group (QC group, n = 8), the STZ induced diabetes mellitus with unilateral nephrectomy model group (DM group, n = 8), the Valsartan treated group (VT group, n = 8) and the TJM treated group (ZY group, n = 9), rats in the latter two groups were modeled as in the DM group and treated with Valsartan (20 mg/kg.d) and TJM (20 g/kg.d) respectively for 12 weeks. The expression of alpha-smooth muscle actin (alpha-SMA) and transforming growth factor-beta 1 (TGF-beta 1) in rats glomeruli were observed by immunohistochemistry assay, and the ratio of alpha-SMA and TGF-beta 1 positive area/total glomerule tuft area (SMA/GT and TGF/GT) were analyzed using computer-assisted image analysis software.

RESULTSIn the NC and the QC groups, only trace of alpha-SMA positive staining was found. But there was prominant alpha-SMA positive staining in glomeruli of the DM group, with SMA/GT and TGF/GT increased significantly (P < 0.01), and marked increase of 24 hrs proteinuria excretion (P < 0.01). As compared with the DM group, the three indexes were all significantly lower in the VT and ZY groups (P < 0.01), and the lowering of proteinuria was more significant in the ZY group than that in the VT group (P < 0.01).

CONCLUSIONThe expression of alpha-SMA in glomeruli in STZ induced diabetic rats with unilateral nephrectomy is pronounced, indicating that phenotypic modulation of mesangial cells involvement in the pathogenesis of diabetic nephropathy. TJM and Valsartan can reduce 24 hrs proteinuria excretion, inhibit the phenotypic modulation of mesangial cells and the expression of TGF-beta 1 in glomeruli of diabetic rats, and the effect of TJM is more potent than that of Valsartan in lowering urinary protein excretion.