www.elsevier.com/locate/brainres Available online at www.sciencedirect.com Research Report Brain infarct volume after permanent focal ischemia is not dependent on Nox2 expression Hyun Ah Kim, Vanessa H. Brait, Seyoung Lee, T. Michael De Silva, Henry Diep, Anja Eisenhardt, Grant R. Drummond, Christopher G. Sobey n Department of Pharmacology, Monash University, Wellington Road, Clayton, Victoria 3800, Australia article info Article history: Accepted 12 September 2012 Available online 18 September 2012 Keywords: Focal ischemia Middle cerebral artery occlusion NADPH oxidase Nox2 Permanent ischemia Reactive oxygen species abstract Reactive oxygen species (ROS) generated by Nox2 oxidase are reported to contribute to infarct damage following cerebral ischemia–reperfusion. Here we have examined for the first time the role of Nox2 expression in outcomes following permanent focal cerebral ischemia. Ischemia was induced by middle cerebral artery filament occlusion (MCAO) for 24 h in wild-type (WT) and Nox2 /y mice. Neurological deficit and the hanging wire test were assessed, and infarct and edema volumes were estimated using thionin-stained brain sections. Genetic deletion of Nox2 had no effect on any outcome measures at 24 h after permanent MCAO. Our data therefore suggest that ROS production by Nox2 oxidase activity plays no significant role in the pathophysiology of cerebral ischemia in the absence of reperfusion. & 2012 Elsevier B.V. All rights reserved. 1. Introduction Despite the high clinical prevalence of ischemic stroke, only one effective therapy exists. Intravenous administration of recom- binant tissue plasminogen activator (rt-PA) to restore cerebral perfusion within 4.5 h of the onset of acute ischemic stroke significantly improves clinical outcomes (Hacke et al., 2008). However, due to its narrow therapeutic window and the increased risk of intracranial hemorrhage associated with rt- PA treatment, there remains a significant unmet need for effective therapies to limit brain injury from acute ischemic stroke. It is well established that in cerebral ischemia and reperfu- sion there is the generation of excessive levels of cytotoxic reactive oxygen species (ROS) such as superoxide anions, hydroxyl radicals, and hydrogen peroxide (Chan, 2001). This situation, known as oxidative stress, results in direct and irreversible oxidative damage to macromolecules and it promotes vascular disease via inactivation of endothelial nitric oxide (Fo ¨ rstermann, 2010). Nox2 oxidase, the phagocy- tic isoform of the NADPH oxidase family of enzymes (Drummond et al., 2011), is thought to be a major source of ROS in the brain, its blood vessels, and in infiltrating leuko- cytes following ischemia and reperfusion, and its expression is increased by pro-inflammatory stimuli (Drummond et al., 2011; Kahles and Brandes, 2012). Pharmacological inhibition of Nox2 oxidase, or genetic deletion of its catalytic subunit, Nox2, is widely reported to attenuate the injury occurring 0006-8993/$ - see front matter & 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.brainres.2012.09.023 Abbreviations: MCA, middle cerebral artery; MCAO, middle cerebral artery occlusion; NADPH, reduced form of nicotinamide adenine dinucleotide phosphate; Nox, NADPH oxidase; Nox2 /y , NADPH oxidase 2-deficient; rCBF, regional cerebral blood flow; ROS, reactive oxygen species; rt-PA, recombinant tissue plasminogen activator; WT, wild type n Corresponding author. Fax: þ61 3 9905 5851. E-mail address: chris.sobey@monash.edu (C.G. Sobey). brainresearch 1483 (2012)105–111