Protective effect of Icariin on the early stage of experimental diabetic nephropathy induced by streptozotocin via modulating transforming growth factor β1 and type IV collagen expression in rats

Ethnopharmacological relevance: Icariin is a major constituent of flavonoid isolated from the plant Herba epimedii, which is used as a traditional Chinese medicine to nourish the kidney and reinforce yang. Therefore, the pharmacological studied of its diabetic nephropathy effect was undertaken to validate its traditional use. Materials and methods: Diabetes was induced in male Sprague-Dawley rats by an injection of streptozotocin (40 mg/kg i.v.). Sustained blood glucose levels (>16.7 mmol/1) were considered as diabetic and selected for experimentation. Thirty rats were randomly divided into three groups: control, diabetic, diabetic + Icariin (80 mg/kg, i.g.) administered 8 weeks from 5th to 12th week. Experiment was carried out at the beginning of 13th week. All rats were anaesthetized and then were killed to remove kidneys. Blood glucose, serum creatinine (Cr), blood urea nitrogen (BUN), the activity of superoxide dismutase (SOD). malondialdehyde (MDA) and hydroxyproline (Hyp) in the kidney tissue were measured. Glomerular morphology was observed by light microscopy. Immunohistochemistry and Western blot were employed to determine the proteins levels of TGF-beta(1) and type IV collagen. Results: The enhancement of Cr and BUN was found in model group, which was significantly attenuated by treatment with Icariin. Meanwhile, elevated MDA and Hyp levels in renal tissue as well as decreased SOD activities in renal tissue were significantly remitted by Icariin. The renal pathological changes in Icariin treatment group were ameliorated. Furthermore, the Icariin decreased the expression of TGF-beta(1) and collagen IV protein. Conclusions: Icariin can evidently relieve renal damage in rats with diabetic nephropathy induced by STZ, which might be related to modulating the expression of collagen IV and TGF-beta(1) protein. (C) 2011 Elsevier Ireland Ltd. All rights reserved.