Apocynin attenuates left ventricular remodeling in diabetic rabbits

// Jiuchun Qiu 1 , Jianping Zhao 1 , Jian Li 1 , Xue Liang 1 , Yajuan Yang 1 , Zhiwei Zhang 1 , Xiaowei Zhang 1 , Huaying Fu 1 , Panagiotis Korantzopoulos 2 , Gary Tse 3, 4 , Tong Liu 1 , Guangping Li 1 1 Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin, People’s Republic of China 2 First Department of Cardiology, University of Ioannina Medical School, Ioannina, Greece 3 Department of Medicine and Therapeutics, Chinese University of Hong Kong, Hong Kong, SAR, P.R. China 4 Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong, SAR, P.R. China Correspondence to: Tong Liu, email: liutongdoc@126.com Guangping Li, email: tjcardiol@126.com Keywords: left ventricular remodeling, diabetes mellitus, oxidative stress, apocynin, NADPH oxidase Received: December 23, 2016      Accepted: March 14, 2017      Published: March 27, 2017 ABSTRACT Introduction: Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases are responsible for the generation of reactive oxygen species, producing vascular and myocardial dysfunction in diabetes mellitus. However, the potential benefits of the NADPH oxidase inhibitor, apocynin, on left ventricular (LV) remodeling remain unknown. Results: In the diabetic group, interventricular septal thickness and left ventricular posterior wall thickness were markedly increased compared to control. These changes were accompanied by increased LV cardiomyocyte cross-sectional area and greater degree of interstitial fibrosis. NO, myeloperoxidase, and malonaldehyde levels in the serum were significantly increased Moreover, protein expression levels of rac1, nuclear factor-κB, transforming growth factor-β, p38, P-p38, and metalloproteinase-9 were also raised. Apocynin treatment prevented all of these structural, histological and biochemical changes and additionally increased superoxide dismutase levels. Methods: Thirty Japanese rabbits were randomized into three groups: control, alloxan-induced diabetes with and without apocynin treatment at 15 mg/kg/day for 8 weeks ( n = 10 for each group). Echocardiography was performed and hemodynamics were assessed by carotid and LV catheterization. LV cardiomyocyte cross-sectional area and interstitial fibrosis were evaluated by histology. Serum nitric oxide (NO), malonaldehyde, myeloperoxidase, superoxide dismutase (SOD) levels, and activity of LV tissue NADPH oxidases was assessed. Expression of proteins involved in pro-inflammatory and pro-fibrotic signaling were determined by Western blotting. Conclusions: Inhibition of NADPH oxidase using apocynin is an effective upstream therapy for preventing diabetes-induced adverse remodeling of the left ventricular myocardium.