Research Report Apocynin protects against global cerebral ischemia–reperfusion-induced oxidative stress and injury in the gerbil hippocampus Qun Wang a , Kenneth D. Tompkins a , Agnes Simonyi a , Ronald J. Korthuis b , Albert Y. Sun b , Grace Y. Sun a, ⁎ a Department of Biochemistry, M743 Medical Sciences Building, University of Missouri–Columbia, Columbia, MO 65212, USA b Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO 65212, USA ARTICLE INFO ABSTRACT Article history: Accepted 9 March 2006 Available online 2 May 2006 Increased production of reactive oxygen species (ROS) following cerebral ischemia– reperfusion (I/R) is an important underlying cause for neuronal injury leading to delayed neuronal death (DND). In this study, apocynin, a specific inhibitor for NADPH oxidase, was used to test whether suppression of ROS by the NADPH oxidase inhibitor can protect against ischemia-induced ROS generation and decrease DND. Global cerebral ischemia was induced in gerbils by a 5-min occlusion of bilateral common carotid arteries (CCA). Using measurement of 4-hydroxy-2-nonenal (HNE) as a marker for lipid peroxidation, apocynin (5 mg/kg body weight) injected i.p. 30 min prior to ischemia significantly attenuated the early increase in HNE in hippocampus measured at 3 h after I/R. Apocynin also protected against I/R-induced neuronal degeneration and DND, oxidative DNA damage, and glial cell activation. Taken together, the neuroprotective effects of apocynin against ROS production during early phase of I/R and subsequent I/R-induced neuronal damage provide strong evidence that inhibition of NADPH oxidase could be a promising therapeutic mechanism to protect against stroke damage in the brain. © 2006 Elsevier B.V. All rights reserved. Keywords: Apocynin NADPH oxidase Oxidative stress Cerebral ischemia–reperfusion Delayed neuronal death Glial activation 1. Introduction Oxidative stress is an important underlying factor in delayed neuronal death (DND) induced by global cerebral ischemia– reperfusion (I/R) (Chan, 2001; Kirino, 2000). The close relation- ship between cerebral ischemia and oxidative stress has generated considerable interest to develop antioxidant agents to combat the deleterious consequences of oxidative insults in ischemia and recirculation injury (Simonyi et al., 2005). There is evidence that the release of reactive oxygen species (ROS) and increase in lipid peroxidation can be detected at a very early time of I/R, e.g., 2–3 h after I/R and at a time without evidence of neuronal cell death (Candelario-Jalil et al., 2001; Wang et al., 2005). Although a number of studies have demonstrated an I/R-induced decrease in mitochondrial membrane potential and a subsequently release of cyto- chrome c, leading to activation of the apoptotic pathway that underlie neuronal cell death (Chan, 2001; Chan, 2004), the source of ROS produced under different phases of I/R has not been investigated in detail. NADPH oxidase is a multi-subunit enzyme complex present at the cell plasma membranes. This enzyme is BRAIN RESEARCH 1090 (2006) 182 – 189 ⁎ Corresponding author. Fax: +1 573 884 4597. E-mail address: Sung@health.missouri.edu (G.Y. Sun). 0006-8993/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.brainres.2006.03.060 available at www.sciencedirect.com www.elsevier.com/locate/brainres