Augmented Superoxide Production By Nox2-Containing NADPH Oxidase Causes Cerebral Artery Dysfunction During Hypercholesterolemia

作者：Miller Alyson A^*; De Silva Michael; Judkins Courtney P; Diep Henry; Drummond Grant R; Sobey Christopher G

来源：Stroke, 2010, 41(4): 784-789.

DOI：10.1161/STROKEAHA.109.575365

• cerebral arteries
• hypercholesterolemia
• NADPH-oxidase
• reactive oxygen species
• vasomotor function

Background and Purpose-We tested the hypothesis that elevated superoxide production by Nox2-NADPH oxidase occurs in cerebral arteries during hypercholesterolemia and causes decreased nitric oxide function.
Methods-Wild-type (WT), apolipoprotein E-deficient (ApoE(-/-)) and Nox2(-/-)/ApoE(-/-) mice were fed a high-fat diet for 7 to 14 weeks. Basal superoxide production by cerebral arteries was measured using L-012 (100 mu mol/L)-enhanced chemiluminescence. Nitric oxide function was assessed in isolated middle cerebral arteries through the constrictor response to N(omega)-nitro-L-arginine methyl ester (L-NAME; 100 mu mol/L). Western blotting was used to measure protein expression of Nox2, p47phox, endothelial nitric oxide synthase, and superoxide dismutases (1-3).
Results-Morphology of cerebral arteries was similar in WT and ApoE(-/-) mice. In ApoE(-/-), but not Nox2(-/-)/ApoE(-/-) mice, superoxide production by cerebral arteries was approximately 50% greater than in WT mice (P<0.05). Moreover, the magnitude of L-NAME-induced contractions of isolated middle cerebral arteries from ApoE(-/-) mice was <50% of that in WT mice (P<0.05), whereas in Nox2(-/-)/ApoE(-/-) mice, the contractile response was comparable to WT responses. In the presence of the superoxide scavenger, tempol (1 mmol/L), L-NAME-induced contractions of middle cerebral arteries were similar between WT and ApoE(-/-) mice. Expression of p47phox was approximately 2-fold higher in ApoE(-/-) versus WT mice, whereas Nox2, endothelial nitric oxide synthase, and superoxide dismutase isoforms were unchanged.
Conclusions-Elevated superoxide production and reduced basal nitric oxide-mediated relaxation occur in cerebral arteries of hypercholesterolemic mice even in the absence of lesions. These changes appear to be exclusively due to increased activity of Nox2-NADPH oxidase, possibly through increased expression of its regulatory subunit p47phox. (Stroke. 2010; 41: 784-789.)

• 出版日期2010-4