RESUMEN
Objective To investigate the mechanism of Shenluotong inhibiting renal interstitial fibrosis by regulating NR3C2/SGK-1/Smad pathway. Methods A total of 48 Wistar rats were randomly divided into sham operation group, model group, Eplerenone group, and Shenluotong group (n = 12). Model group, Eplerenone group, and Shenluotong group used unilateral ureteral obstruction (UUO) method to establish rat renal interstitial fibrosis model. After the operation, the rats in the eplerenone group were treated with eplerenone at a dose of 100 mg/(kg∙d). Rats in the Shenluotong group were oral given Shenluotong decoction at a dose of 26 g/(kg∙d) and Sham operation group and model group were administrated equal volume of saline once daily for continuous 10 d. Laser confocal microscopy was used to detect mineralocorticoid receptor NR3C2 expression. The expressions of SGK-1, TGF-β1, Smad4, and Smad7 in renal tissues were detected by immunohistochemistry, Western Blot and Real time-PCR. Results In the sham operation group, NR3C2 was expressed in the cytoplasm of renal tubular epithelial cells and was not expressed in the nucleus. The expression of NR3C2 in the UUO rat was significantly up-regulated in cytoplasm and positive expression was observed in the nucleus. The expression of NR3C2 in the nucleus of cells in the Eplerenone group and Shenluotong group was significantly decreased when compared with the model group. Compared with the sham-operated group, the expression of SGK-1, TGF-β1, and Smad4 was significantly up-regulated and the expression of Smad7 was significantly decreased (P < 0.05, 0.01) in the other groups. Compared with model group, the expression range and intensity of TGF-β1 and Smad4 were significantly decreased in Eplerenone group and Shenluotong group (P < 0.05, 0.01), and the expression range and intensity of Smad7 were significantly increased (P < 0.01). Conclusion Shenluotong can inhibit renal interstitial fibrosis through blocking the activation of mineralocorticoid receptor, reducing the level of SGK-1, and regulating the Smads signal pathway to inhibit the overexpression of TGF-β1.
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Summary: The role of serum and glucocorticoid-induced kinase 1 (SGK1) pathway in the connective tissue growth factor (CTGF) expression was investigated in cultured human mesangial cells (HMCs) under high glucose. By using RT-PCR and Western blot, the effect of SGK1 on the CTGF expression in HMCs under high glucose was examined. Overexpression of active SGK1 in HMCs transfected with pIRES2-EGFP-S422D hSGK1 (SD) could increase the expression of phosphorylated SGK1 and CTGF as compared with HMCs groups transfected with pIRES2-EGFP (FP) under high glucose or normal glucose. Overexpression of inactive SGK1 in HMCs transfected with pIRES2-EGFP-K127N hSGK1 (KN) could decrease phosphorylated SGK1 and CTGF expression as compared with HMCs groups transfected with FP under high glucose. In conclusion, these results suggest that high glucose-induced CTGF expression is mediated through the active SGK1 in HMCs.