Original article NADPH oxidase inhibition prevents cocaine-induced up-regulation of xanthine oxidoreductase and cardiac dysfunction Marc Isabelle, Aurélia Vergeade, Fabienne Moritz, Brigitte Dautréaux, Jean-Paul Henry, Françoise Lallemand, Vincent Richard, Paul Mulder, Christian Thuillez, Christelle Monteil ⁎ Univ Rouen, Rouen, F-76183 France, INSERM U644, Rouen, F-76183, France Received 10 July 2006; received in revised form 10 November 2006; accepted 20 November 2006 Abstract Oxidative stress is involved in the pathogenesis of cocaine-induced cardiomyopathy. In the present study, we aimed to determine the enzymatic sources of reactive oxygen species (ROS) production, namely NADPH oxidase and xanthine oxidoreductase (XOR) in male Wistar rats treated for 7 days with cocaine (2×7.5 mg/kg/day, ip) or cocaine with a NADPH oxidase inhibitor (apocynin, 50 mg/kg/day, po) or a XOR inhibitor (allopurinol, 50 mg/kg/day, po). Cocaine-induced cardiac dysfunction is associated with an increase in NADPH oxidase and XOR activities (59% and 29%, respectively) and a decrease in catalase activity. Apocynin or allopurinol treatment prevents the cocaine-induced cardiac alteration by restoration of cardiac output, stroke volume and fractional shortening. This is associated with a reduction of the myocardial production of superoxide anions and an enhancement of catalase activity. Surprisingly, apocynin treatment prevents XOR up-regulation supporting the hypothesis that NADPH oxidase-derived ROS play a role in modulating ROS production by XOR. These data suggest that NADPH and xanthine oxidase act synergically to form myocardial ROS and clearly demonstrate that their inhibition may be critical in preventing the initiation and progression of cocaine-induced LV dysfunction. © 2006 Elsevier Inc. All rights reserved. Keywords: Cocaine; Oxidative stress; NADPH oxidase; Xanthine oxidase; Cardiac function; Reactive oxygen species 1. Introduction Cocaine consumption induces cardiovascular disorders associated with myocardial ischemia, arrhythmia, dilated cardiomyopathy and cardiac hypertrophy [1]. Although phar- macological actions of cocaine, such as the sympathomimetic and the anesthetic local effects must be considered, the role of oxidative stress is clearly demonstrated as an early triggering event of cocaine-induced cardiomyopathy [2–5]. ROS can be generated in the heart by several mechanisms after cocaine administration. They can be produced by autooxidation of catecholamines which are accumulated into myocardium, due to the interference of cocaine with mono- amine reuptake systems [6]. Catecholamines may also contrib- ute to the production of ROS through adrenergic stimulation [7–9]. Indeed, adrenoreceptors are G-protein-coupled receptors which can participate to activation of NADPH oxidase [10,11], a major source of induced ROS production in cardiovascular system. Moreover, NADPH oxidase generated ROS may play an important role in modulating ROS production by other enzymatic sources such as endothelial NOS [12] or xanthine oxidoreductase (XOR) [13]. XOR is a key enzyme in purine metabolism, but it is also known for its ability to produce ROS and to play an important role in the cardiovascular system. XOR exists in two alternative forms deriving from the same 150-kDa gene product, xanthine dehydrogenase (XDH) which predomi- nates in vivo and xanthine oxidase (XO). The conversion of XDH to XO form may occur either irreversibly after limited proteolysis leading to a 130 kDa product or reversibly by phosphorylation or thiol oxidation of the 150 kDa protein [14]. Within endothelial cells, a conversion of XO from XDH occurs after oxidative mechanisms, probably mediated by NADPH oxidase-generated ROS [13]. Journal of Molecular and Cellular Cardiology 42 (2007) 326 – 332 www.elsevier.com/locate/yjmcc ⁎ Corresponding author. INSERM U644, UFR de Médecine et de Pharmacie, 22 boulevard Gambetta, 76183 Rouen, France. Tel.: +33 2 35 14 84 75; fax: +33 2 35 14 83 65. E-mail address: christelle.monteil@univ-rouen.fr (C. Monteil). 0022-2828/$ - see front matter © 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.yjmcc.2006.11.011