Total triterpene acids, isolated from Corni Fructus, ameliorate progression of renal damage in streptozotocin-induced diabetic rats

To investigate whether total triterpene acids (TTAs), isolated from Cornus Fructus, attenuates renal function by reducing oxidative stress and down-regulating the expression of transforming growth factor beta(1) (TGF-beta(1)). Diabetes was induced by an injection of streptozotocin (40 mg/kg intravenously). Thirty rats were randomly divided into three groups: control group, diabetic model group and TTAs treatment group (50 mg/kg, intragastrically) administrated for 8 weeks from 5th to 12th week. All rats were anaesthetized and then were killed to remove kidneys. The renal function and redox enzyme system parameters were tested. Glomerular morphology was observed by a light microscopy. Immunohistochemistry and Western blot assays were employed to determine the protein levels of TGF-beta(1). TTAs attenuated the levels of urinary protein, serum creatinine and blood urea nitrogen, although it did not significantly reduce the level of glucose. In addition, TTAs decreased the malondialdehyde while increased superoxide dismutase, catalase and glutathione peroxide activities in diabetic rats. The renal pathological changes in TTAs treatment group were ameliorated. Furthermore, TTAs also ameliorated the expression of TGF-beta(1). TTAs improved renal function via reducing oxidative stress and down-regulation the expression of TGF-beta(1) in diabetic rats.