Effects of soybean isoflavones on Wnt/β-catenin and the TGF-β1 signaling pathway in renal tissue of type 2 diabetic rats

Abstract

To observe the effect of Soyisoflavones (SI) on the expression of Wnt/β-catenin signaling pathway elements, transforming growth factor-β (THGF-β) and its related proteins in the renal interstitia of diabetic nephropathic (DN) rats, 48 DN rats were randomly divided into 4 groups: DN model group (group DN), soybean isoflavone treatment group (group DA), DN model group + losartan treatment group (group DL), DN model group + soybean isoflavones combined with losartan treatment group (group SL). Each group comprised 12 rats. Twelve healthy Wistar rats were selected as normal controls (group N). After 12 weeks of continuous administration of soybean isoflavone or losartan or those two combined, the body weight of rats was recorded and serum urea nitrogen (BUN) and creatinine (Scr) were measured. The expression of Wnt4, β-catenin, and TGF-β1 proteins, as well as mRNA, in the renal interstitium were detected by immunohistochemistry and real-time quantitative PCR (FQ-PCR). In all the groups, Wnt4, β-catenin and TGF-β1 protein were only expressed in renal interstitial and renal tubular epithelial cells. There was no significant difference between group DA and group DL (P>0.05). FQ-PCR results showed that Wnt4, β-catenin and TGF-β1 mRNA were consistent with the expression of these proteins in the renal tissue of each group. Soy isoflavones can reduce 24-h urinary protein quantification, alleviate renal interstitial pathological damage, and regulate the expression of Wnt4, β-catenin and TGF-β1 in the renal interstitium. This suggests that soybean isoflavones could delay the process of renal interstitial fibrosis in DN rats by decreasing the expression of Wnt4, β-catenin and TGF-β1 in the renal interstitium, thus demonstrating that soybean isoflavones plus losartan have the best protective effects against diabetes-induced renal fibrosis.