Administration of apocynin in drinking water ameliorates transient cerebral ischemia-induced brain damage and behavioral deficits in mice

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Acute ischemic stroke is the third leading cause of death in developed countries and the most frequent cause of permanent disability in adults worldwide. Despite advances in the understanding of the pathophysiology of cerebral ischemia, therapeutic options remain limited. Inflammation following ischemic stroke is known to contribute to neurological injury. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) is well known as a major source for superoxide radical generation in leukocytes. Superoxide radicals play a significant role in brain ischemia-reperfusion (I/R) injury. Recently, several forms of this oxidase have been found in a variety of non-immune cells including neurons and glial cells. Apocynin is a NOX inhibitor that has been studied as a potential treatment in experimental stroke. The anti-inflammatory activity of apocynin has been demonstrated in a variety of cells and animal models of inflammation. Apocynin after metabolic conversion, inhibits the assembly of NADPH oxidase that is responsible for reactive oxygen species (ROS) production. In our study, apocynin was used to test whether suppression of ROS by the NADPH oxidase inhibitor can protect against ischemia-induced ROS generation. Focal cerebral ischemia was induced in mice (C57BL/6J male mice) that used a dietary preventative protocol in which apocynin was added into the drinking water so that animals received 50mg/kg dose each day for 5 days before surgery (Intraluminal filament MCAO). Mice used were subjected to 90-120 minutes of focal ischemia induced by MCAO followed by 24 hrs reperfusion. Drinking apocynin group prior to ischemia significantly attenuated infarct volume and improved functional outcome. The neuroprotective effects of apocynin against ROS production during early phase 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.