title: Nox2 oxidase activity accounts for the oxidative stress and vasomotor dysfunction in mouse cerebral arteries following ischemic stroke.
abstract: OBJECTIVE
  Post-ischemic oxidative stress and vasomotor dysfunction in cerebral arteries may increase the likelihood of cognitive impairment and secondary stroke. However, the underlying mechanisms of post-stroke vascular abnormalities, as distinct from those causing primary brain injury, are poorly understood. We tested whether augmented superoxide-dependent dysfunction occurs in the mouse cerebral circulation following ischemia-reperfusion, and evaluated the role of Nox2 oxidase.
  
  
  METHODS
  Cerebral ischemia was induced in male C57Bl6/J wild-type (WT) and Nox2-deficient (Nox2(-/-)) mice by middle cerebral artery occlusion (MCAO; 0.5 h), followed by reperfusion (23.5 h). Superoxide production by MCA was measured by L-012-enhanced chemiluminescence. Nitric oxide (NO) function was assessed in cannulated and pressurized MCA via the vasoconstrictor response to N(ω)-nitro-L-arginine methyl ester (L-NAME; 100 µmol/L). Expression of Nox2, the nitration marker 3-nitrotyrosine, and leukocyte marker CD45 was assessed in cerebral arteries by Western blotting.
  
  
  RESULTS
  Following ischemia-reperfusion, superoxide production was markedly increased in the MCA of WT, but not Nox2(-/-) mice. In WT mice, L-NAME-induced constriction was reduced by ∼50% in ischemic MCA, whereas ischemia-reperfusion had no effect on responses to L-NAME in vessels from Nox2(-/-) mice. In ischemic MCA from WT mice, expression of Nox2 and 3-nitrotyrosine were ∼1.4-fold higher than in the contralateral MCA, or in ischemic or contralateral vessels from Nox2(-/-) mice. Vascular CD45 levels were unchanged by ischemia-reperfusion.
  
  
  CONCLUSIONS
  Excessive superoxide production, impaired NO function and nitrosative stress occur in mouse cerebral arteries after ischemia-reperfusion. These abnormalities appear to be exclusively due to increased activity of vascular Nox2 oxidase.
authors.affiliation: Department of Pharmacology, Monash University, Clayton, Victoria, Australia.
authors.forename: T Michael
authors.initials: TM
authors.lastname: De Silva
authors.forename: Vanessa H
authors.initials: VH
authors.lastname: Brait
authors.forename: Grant R
authors.initials: GR
authors.lastname: Drummond
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Sobey
authors.forename: Alyson A
authors.initials: AA
authors.lastname: Miller
mesh_terms: D000818:Animals; D002536:Cerebral Arteries / Q000378:metabolism*; D002560:Cerebrovascular Circulation; D003433:Crosses, Genetic; D007511:Ischemia; D017493:Leukocyte Common Antigens / Q000096:biosynthesis; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D020768:Middle Cerebral Artery / Q000378:metabolism / Q000473:pathology; D008954:Models, Biological; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism*; D018384:Oxidative Stress; D015427:Reperfusion Injury; D020521:Stroke / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: D008562:Membrane Glycoproteins; D013481:Superoxides; C002744:3-nitrotyrosine; D014443:Tyrosine; C488842:Cybb protein, mouse; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D017493:Leukocyte Common Antigens