摘要
Objective To investigate the role of transforming growth factor-131 （TGF-β1）/Smad4 pathway in development of renal fibrosis in streptozotocin （STZ）-induced diabetic nephropathy （DN） rats and explore its possible mechanism. Methods Male Wistar rats weighing 180-220 g were divided into 5 groups： group A （ normal control）, group B [ diabetes mellitus （DM） 2 weeks ], group C （ DM 4 weeks）, group D （ DM 8 weeks）, and group E （ DM 16 weeks）. Except for the normal control group, other groups were induced DM by single injection of STZ （55 mg/kg） respectively. Blood glucose level, serum creatinine, and 24-hour urine protein were examined. Expressions of TGF-β1 and Smad4 protein and mRNA in kidney were detected using immunohistochemical technique, Western blot, and real-time PCR. mRNA expressions of stromelysin-1 （ MMP-3 ）, tissue inhibitor of metalloproteinase-1 （ TIMP-1 ）, and collagen Ⅲ in kidney were also detected by real-time PCR. Results The levels of blood glucose, serum creatinine, and 24-hour urine protein in rats of group B, C, D, and E were higher than those of the control group. With the progression of renal fibrosis, the expressions of TGF-β1 and Smad4 protein and mRNA in kidney of diabetic rats elevated. In addition, the renal MMP-3 mRNA expression diminished in diabetic rats, while TIMP-1 and collagen Ⅲ mRNA increased. Conclusions In STZ-induced diabetic rats, the TGF-β1/Smad4 appears to play an important role in renal fibrosis of DN. The increased expression of TGF-β1 and Smad4 might result in the transcriptional regulation of downstream target genes of TGF-β1/Smad4 pathway, which contributes to the progression of renal fibrosis in diabetic rats.
