Apocynin Ameliorates Pressure Overload-Induced Cardiac Remodeling by Inhibiting Oxidative Stress and Apoptosis
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Physiol. Res. 66: 741-752, 2017 Apocynin Ameliorates Pressure Overload-Induced Cardiac Remodeling by Inhibiting Oxidative Stress and Apoptosis J.-J. LIU1*, Y. LU2*, N.-N. PING3, X. LI1, Y.-X. LIN1, C.-F. LI4 * These authors contributed equally to this work as first authors. 1Department of Physiology and Pathophysiology, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi Province, China, 2Department of Pharmacology, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi Province, China, 3Shaanxi Blood Center, Xi'an, Shaanxi Province, China, 4Department of Obstetrics and Gynecology, The First Affiliated Hospital of Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi Province, China Received November 10, 2015 Accepted June 21, 2016 On-line October 26, 2016 Summary Key words Oxidative stress plays an important role in pressure overload- Apocynin • Cardiac remodeling • Angiotension II • NADPH induced cardiac remodeling. The purpose of this study was to oxidase • Reactive oxygen species • Apoptosis. determine whether apocynin, a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor, attenuates pressure Corresponding author overload-induced cardiac remodeling in rats. After abdominal C.-F. Li, Department of Obstetrics and Gynecology, The First aorta constriction, the surviving rats were randomly divided into Affiliated Hospital of Xi'an Jiaotong University Health Science four groups: sham group, abdominal aorta constriction group, Center, Xi'an 710061, Shaanxi Province, China. Fax: +86 29 apocynin group, captopril group. Left ventricular pathological 82657497. E-mail: [email protected] changes were studied using Masson’s trichrome staining. Metalloproteinase-2 (MMP-2) levels in the left ventricle were Introduction analyzed by western blot and gelatin zymography. Oxidative stress and apoptotic index were also examined in cardiomyocytes Heart failure (HF) is the end stage of various using dihydroethidium and terminal deoxynucleotidyl transferase kinds of cardiovascular diseases (CVD), which is a leading dUTP nick end labeling (TUNEL), respectively. Our results showed cause of morbidity and mortality in middle age and aged that abdominal aorta constriction significantly caused excess people (Greenberg et al. 2012, Al Suwaidi et al. 2012). collagen deposition and cardiac insult. Treatment with apocynin Cardiac remodeling has been suggested to be associated significantly inhibited deposition of collagen and reduced the level with poor prognosis in patients with cardiovascular of MMP-2. Furthermore, apocynin also decreased the NADPH disorders (Cohn et al. 2000, Gonzalez et al. 2011). oxidase activity, reactive oxygen species production and Cardiomyocyte hypertrophy, apoptosis, and subsequent cardiomyocyte apoptotic index. Interestingly, apocynin only fibroblast proliferation play critical roles in the process of inhibited NADPH oxidase activity without affecting its expression cardiac remodeling, which ultimately accelerates cardiac or the level of angiotension II in the left ventricle. In conclusion, fibrosis and contributes to cardiac dysfunction (Hassan et apocynin reduced collagen deposition, oxidative stress, and al. 2012, Mitra et al. 2013). inhibited apoptosis, ultimately ameliorating cardiac remodeling by The renin-angiotensin system (RAS) plays mechanisms that are independent of the renin-angiotensin an important role in the cardiac remodeling process and is system. involved in the pathogenesis of HF (Nagalingam et al. 2013). Growing evidence confirms that activation of the PHYSIOLOGICAL RESEARCH • ISSN 0862-8408 (print) • ISSN 1802-9973 (online) 2017 Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic Fax +420 241 062 164, e-mail: [email protected], www.biomed.cas.cz/physiolres 742 Liu et al. Vol. 66 RAS leads to a large generation of reactive oxygen species study, were supplied by the Experimental Animal Centre (ROS) that contribute to cardiomyocyte hypertrophy, of Xi’an Jiaotong University. The animals were housed apoptosis, and fibrosis in cardiac remodeling (Choudhary under controlled temperatures (20±5 °C), humidity et al. 2008). Captopril, as the earliest angiotensin (60-75 %), and light/dark cycles (12 h day/12 h night). All converting enzyme inhibitor (ACEI), exerts experimental procedures were in compliance with the cardioprotective effects by increasing tissue antioxidant Guide for the Care and Use of Laboratory Animals activity, scavenging different types of ROS, and then published by the National Institutes of Health (NIH decreasing the deposition of collagen, inflammatory publication No. 85-23, revised 1996). The animal protocols response and myocyte apoptosis, which ultimately were approved by the Animal Care and Use Committees of ameliorating cardiac remodeling (St John Sutton et al. Xi'an Jiaotong University. 1997, Li et al. 2015). Recent studies showed that ROS are produced by mitochondria, xanthine oxidases, cytochrome Induction of cardiac remodeling via abdominal aorta P450 reductase, and nicotinamide adenine dinucleotide constriction and drug administration phosphate (NADPH) oxidase (Bedard and Krause 2007). Abdominal aorta constriction was performed as Among these, NADPH oxidase is a primary source for described previously (Chen et al. 2010). Briefly, after ROS production at the presentation of CVD. NADPH being fasted for 12 h, rats (n=50) were anesthetized with oxidase contains phox units (gp91phox, p22phox, p40phox, pentobarbital sodium (45 mg/kg) by intraperitoneal p47phox, p67phox) and the small GTPase (Rac1 or Rac2) injection, and the aorta was dissected above the two renal (Cai et al. 2003, Jin et al. 2008, Lassegue and Griendling arteries. A silver clip (0.70 mm internal diameter) was 2010). ROS derived from NADPH oxidase play a vital role placed on the aorta abdominalis above the level of the left in pathophysiological conditions such as atrial fibrillation, renal arteries. 7 days after the surgical procedure, rats were myocardial infarction, and hypertension (Liu et al. 2012b, randomly divided into four groups: abdominal aorta Al-Rasheed et al. 2013, Cheng et al. 2014). Therefore, constriction group (AAC, n=7), apocynin (Apo) + AAC inhibition of this enzyme may be an attractive and potential group (Apo, 200 mg/kg/day, n=8), captopril (Cap) therapeutic target for the treatment of HF (Schwarzer et al. + AAC group (Cap, 75 mg/kg/day, n=8). The Sham group 2014). (n=10) was subjected to the same surgical procedure Apocynin (4-hydroxy-3-methoxy-acetophenone), without clip placement. All drugs were purchased from a constituent of the Himalayan herb Picrorhiza kurrooa Sigma (St Louis, MO, USA) and dissolved in drinking Royle (Scrophulariaceae) has been used as an inhibitor of water. The animals were sacrificed 8 weeks after surgery NADPH oxidase (Engels et al. 1992, Babior et al. 2002). and the hearts were collected for histological analysis Recent studies showed that apocynin can improve atrial (Fig. 1). fibrillation in hearts with infarction, and also has antihypertensive effects on spontaneously hypertensive rats Hemodynamic data analysis (Sovari et al. 2008, Ciarcia et al. 2010). We previously To examine the effect of Apo on cardiac function, reported that apocynin ameliorated pressure overload- we measured hemodynamics 8 week after abdominal aorta induced cardiac hypertrophy by reducing ROS production constriction. Animals were anesthetized with pentobarbital (Liu et al. 2010). However, it is not clear whether apocynin sodium (45 mg/kg) by intraperitoneal injection, and the can attenuate cardiac remodeling in rats with pressure right carotid arterial connected to pressure transducers was overload. Therefore, in the present study we investigated introduced into the left ventricle to measure heart rate whether apocynin might be able to attenuate cardiac (HR), systolic arterial pressure (SAP), left ventricular remodeling in Sprague-Dawley (SD) rats with pressure systolic pressure (LVSP), left ventricular end-diastolic overload. We also further explored the possible pressure (LVEDP) and maximum/minimum values of the mechanisms of action of apocynin for suppressing cardiac first derivative of left ventricular pressure (dp/dtmax and fibrosis. dp/dtmin). All data were recorded with PowerLab (AD Instruments) in all groups under a 30-minute steady- Material and Methods state condition. Animals Blood sampling and tissue preparation Adult male SD rats (8-10 week-old) used in this At the eighth week, all rats were anesthetized 2017 Apocynin Ameliorates Cardiac Remodeling by Inhibiting Oxidative Stress 743 with pentobarbital sodium by intraperitoneal injection. and sliced transversely from apex to base freeing the right Blood was drawn from the abdominal aorta, allowed to ventricular wall. The left ventricular wall was snap- clot, centrifuged at 5,000 x g for 10 min and the serum frozen in liquid nitrogen and store at -80 °C. The was stored at -80 °C for further analysis. Next, the whole angiotensin II (Ang II) activity (concentration) in tissue hearts from the rats were quickly removed, washed with and serum was analyzed using a commercial kit (Dong cold phosphate buffered saline (2.7 mM KCl, 137 mM Ya Radioimmunology Institute, Beijing, China) NaCl, 10 mM Na2HPO4, and 2 mM KH2PO4 at pH 7.4), following the manufacturer’s instructions. Fig. 1. The experimental groups used in the study. Rats (n=40) were anesthetized with pentobarbital sodium (45 mg/kg) by intraperitoneal injection, and a silver clip (0.70 mm internal diameter)