ABSTRACT
<p><b>OBJECTIVE</b>To observe the effect of Tripterygium glycosides (TG) on the expression of hypoxia-inducible factor-1α and endothelin-1 in the kidney of diabetic rats and explore the possible mechanism underlying the protective effect of TG against diabetic nephropathy.</p><p><b>METHODS</b>Sixty 8-week-old male SD rats were randomly divided into normal control group (n=10) and streptozotocin-induced diabetes mellitus (DM) model group (n=50). The diabetic model rats were then randomly divided into DM group, low-dose (8 mg/kg) and high-dose (16 mg/kg) TG treatment groups, and Irbesartan (50 mg/kg) treatment group. After 8 weeks, the levels of blood glucose (BG), 24-h urine protein (24 h Upro), serum creatinine (Scr) and blood urea nitrogen (BUN) were measured. The pathological changes in the renal tissues were examined by optical microscopy, and the mean glomerular area (MGA) and mean glomerular volume (MGV) were measured with pathological image analysis. Immunohistochemical and Western blotting were used to detect the expression of HIF-1α and ET-1 protein in the renal tissue, and their mRNA expressions were detected using real-time fluorescence quantitative PCR.</p><p><b>RESULTS</b>HIF-1α and ET-1 expression increased in the kidney of diabetic rats. Compared with the diabetic model rats, the rats receiving TG and Irbesartan treatment showed decreased levels of Scr, BUN, 24h Upro, MGA and MGV, improved renal histopathology, and reduced expression of HIF-1α and ET-1 mRNA and protein in the renal tissue. These changes were more obvious in high-dose TG treatment group. Correlation analysis showed that the expression of HIF-1α was positively correlated with that of ET-1, and they were both positively correlated with kidney weight index (KW/BW), 24 h Upro, MGA, and MGV.</p><p><b>CONCLUSION</b>HIF-1α and ET-1 are overexpressed in the kidney of diabetic rats. TG can improve kidney damage in diabetic rats and delay the development of diabetic nephropathy by inhibiting the HIF-1α and ET-1 expression.</p>
Subject(s)
Animals , Male , Rats , Biphenyl Compounds , Pharmacology , Blood Glucose , Blood Urea Nitrogen , Creatinine , Blood , Diabetes Mellitus, Experimental , Metabolism , Endothelin-1 , Metabolism , Glycosides , Pharmacology , Hypoxia-Inducible Factor 1, alpha Subunit , Metabolism , Kidney , Metabolism , Rats, Sprague-Dawley , Tetrazoles , Pharmacology , Tripterygium , ChemistryABSTRACT
The study is to explore the effect of total glucosides of paeony (TGP)on Wnt/β-catenin signal transduction pathway expression in kidney of diabetic rats, and discuss the protection of TGP in diabetic nephropathy and possible mechanism. Ninety male SD rats of 8 weeks age were randomly divided into normal control group (n = 10) and model group (n = 80). Rats of the normal control group were fed with regular diet, while rats of the model group were fed with high-fat high-sugar diet and 4 weeks later were given an intraperitoneal injection of 35 mg x kg(-1) streptozotocin (STZ). The successfully induced type 2 diabetic rat models were then randomly divided into DM group, three TGP (50, 100, 200 mg x kg(-1) x d(-1)) treatment group and tripterygium wilfordii glycosides (8 mg x kg(-1) x d(-1)) control group. Rats of DM group and each treatment group were given high-fat high-sugar diet. At week 14, the levels of blood sugar, 24 hour urine protein, serum creatinine and blood urea nitrogen were tested. The rats were then sacrificed. Renal pathological changes were examined. Renal tissue Wnt-1 and β-catenin expressions were detected by immunohistochemical assay. Wnt-1 mRNA and β-catenin mRNA expression was semi-quantified by RT-PCR. Wnt-1 protein and β-catenin protein expression was semi-quantified by Western blot. The Result show that Wnt-1 and β-catenin expression increased in kidney of high-fat high-sugar induced type 2 diabetic rats. Compared with diabetic group, the level of serum creatinine, blood urea nitrogen, 24 h urine protein, mean glomerular area and mean glomerular volume were decreased, renal histopathology were improved, expression of Wnt-1 and β-catenin mRNA and protein was reduced in TGP group. Tripterygium wilfordii glycosides had the similar effect. In conclusion, these results showed that Wnt/β-catenin abnormal activation in kidney of type 2 diabetic rats, TGP can improve kidney damage in diabetic rats and delay the development of diabetic nephropathy by inhibit the Wnt/β-catenin signaling pathway.