Effects of NADPH oxidase inhibitor on diabetic nephropathy in OLETF rats: The role of reducing oxidative stress in its protective property Soo Min Nam a , Mi Young Lee b , Jang Hyun Koh b , Jun Ho Park c , Jang Yel Shin b , Young Goo Shin b , Sang Baek Koh c , Eun Young Lee d , Choon Hee Chung b,e, * a Department of Internal Medicine, Sun General Hospital, Daejeon, Republic of Korea b Department of Internal Medicine, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea c Department of Preventive Medicine & Institute of Occupational Medicine, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea d Department of Internal Medicine, SoonChunHyang University College of Medicine, Cheonan, Republic of Korea e Institute of Lifelong Health, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea diabetes research and clinical practice 83 (2009) 176–182 article info Article history: Received 24 April 2008 Received in revised form 2 October 2008 Accepted 20 October 2008 Published on line 25 December 2008 Keywords: Apocynin Diabetic nephropathy NADPH oxidase Oxidative stress abstract Diabetic nephropathy is the most serious complication in diabetes mellitus. Oxidative stress via nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and vascular endothe- lial growth factor (VEGF) pathway play critical roles in the development of diabetic nephro- pathy. We evaluated the effects of apocynin, NADPH oxidase inhibitor on diabetic nephropathy in a type 2 diabetic rat model. Sixteen Otsuka Long Evans Tokushima Fatty (OLETF) rats and 9 Long Evans Tokushima Otsuka (LETO) were divided into the following three groups: LETO rats (n = 9), control OLETF rats (n = 7) and apocynin-treated OLETF rats (n = 9). We examined body weights, plasma glucose levels, urinary albumin–creatinine ratio (ACR) and protein–creatinine ratio (PCR). At 50 weeks, experimental rats were sacrificed and their kidneys were extracted for hematox- ylin eosin stain, immunohistochemical VEGF stain and VEGF mRNA real-time RT-PCR. To examine oxidative stress, we checked 24 h urinary 8-OHdG (8-hydroxy-2 0 -deoxyguanosine) and MDA (malondialdehyde). Urinary protein and albumin excretions were reduced after apocynin treatment, though apocynin could not significantly decrease serum glucose levels. There were improvements of glomerular and mesangial expansion in the apocynin-treated OLETF rats. Apocynin significantly decreased optical density of glomerular VEGF expression in immunohisto- chemical stain and reduced the concentration of 24 h urinary 8-OHdG and MDA. From these results, it was suggested that apocynin may have the potential to protect against diabetic nephropathy via amelioration of oxidative stress. # 2008 Elsevier Ireland Ltd. All rights reserved. * Corresponding author at: Department of Internal Medicine, Yonsei University Wonju College of Medicine, 162 Ilsan-Dong, Wonju 220-701, Republic of Korea. Tel.: +82 33 741 0506; fax: +82 33 731 5884. E-mail address: cchung@yonsei.ac.kr (C.H. Chung). Contents lists available at ScienceDirect Diabetes Research and Clinical Practice journal homepage: www.elsevier.com/locate/diabres 0168-8227/$ – see front matter # 2008 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.diabres.2008.10.007