Abstract TP248: Nos Inhibitor Is An Effective Adjuvant To Reperfusion Therapy In Ischemic Stroke In Mice

Abstract

Background: Inhibition nitric oxide synthase (NOS) has been shown to paradoxically protect against ischemic brain injury by an unknown mechanism. Recently, we found that NOS inhibitor, N (gamma)-nitro-L-arginine methyl ester (L-NAME), protects primary cultures of endothelial cells and neurons against oxygen-glucose deprivation-reoxygenation injury by preventing NOS uncoupling. Thus, the objective of the present study was to demonstrate the effectiveness of locally administered L-NAME against ischemia-reperfusion (I-R) injury. Methods: Transient focal cerebral ischemia in male mice (C57Bl/6, 2-4 months) was achieved by filament method of MCAO with a 60 min occlusion. We employed a novel approach to inject L-NAME (1 mg/Kg dosages at a rate of 60 ug/minute) locally into the ischemic zone by threading a catheter up the middle cerebral artery. This was timed to the onset of reperfusion by rapidly followng the removal of the occlusion with silicon suture. Following 24-hour reperfusion, infarct size was determined by 2,3,5-Triphenyltetrazolium chloride (TTC) staining and neurological functioning was recorded employing standard neurological score (0-4 range) and Rotarod performance test. Results: Admnistration of FITC Dextran 40K and fluroscence microscopy of the brain slices 1 hour post-ischemia confirmed the effective delivery of injected L-NAME into ischemic tissue. Localized injection of L-NAME was protective against I-R injury and promoted significant recovery of neurological and motor function (Figure). Conclusion: NOS inhibition could serve as an adjuvant for reperfusion therapies of ischemic stroke.