Effect of catalpol on diabetic nephropathy in rats

Purpose: To investigate the effect of catalpol on diabetic nephropathy in rats. Methods: Male Sprague-Dawley rats were randomly divided into two groups and fed with normal pallet diet (NPD) or high-fat diet (HFD) for 4 weeks respectively. Then the HFD-fed rats were injected with 35 mg/kg streptozotocin (STZ) for establishing diabetic model. The diabetic rats were randomly divided into five groups: model group, model plus catalpol 30, 60, 120 mg/kg groups and model plus metformin 200 mg/kg group. The NPD-fed rats were randomly divided into two groups: normal control group and normal plus catalpol 60 mg/kg control group. After administration for 10 weeks, random blood glucose (RBG), glycated serum protein (GSP), 24 h urinary protein excretion (UPE), serum creatinine (Scr), blood urea nitrogen (BUN), and kidney weight index (KWI) were determined. The kidney pathological changes were evaluated by periodic acid-Schiff(PAS) staining. The concentrations of angiotensin II (Ang II), transforming growth factor-beta 1 (TGF-beta 1), connective tissue growth factor (CTGF), fibronectin (FN), collagen type IV (Col IV) in renal cortex were determined. Real time RT-PCR was used to detect the mRNA expressions of TGF-beta 1 and CTGF. Results: Catalpol could significantly reduce the KWI, improve the kidney function and pathological change, decrease the tissue level of Ang II, TGF-beta 1, CTGF, FN, Col IV. Catalpol could also down regulate the mRNA expressions of TGF-beta 1 and CTGF in renal cortex. Conclusion: Catalpol may have beneficial effects against diabetic nephropathy. The mechanisms may be related to reducing the extracellular matrix accumulation by restraining the expression of TGF-beta 1, CTGF and Ang II. (C) 2013 Elsevier GmbH. All rights reserved.