Jackman K A, Miller A A, De Silva T M, Crack P J, Drummond G R, Sobey C G
Department of Pharmacology, Monash University, Clayton, VIC, Australia.
Br J Pharmacol. 2009 Feb;156(4):680-8. doi: 10.1111/j.1476-5381.2008.00073.x. Epub 2009 Jan 23.
Reactive oxygen species (ROS) derived from Nox2-containing reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity is reportedly detrimental in cerebrovascular disease. However, ROS generation by other Nox isoforms may have a physiological role. No Nox2-selective inhibitors have yet been identified, and thus it is unclear whether isoform non-selective Nox inhibitors would necessarily improve outcome after stroke. We assessed the effect of apocynin on cerebrovascular ROS production and also on outcome following cerebral ischaemia when administered either before ischaemia or after cerebral reperfusion. The involvement of Nox2-containing NADPH oxidase in the effects of apocynin was assessed using Nox2(-/-) mice.
Transient cerebral ischaemia was induced by 0.5 h middle cerebral artery occlusion followed by 23.5 h reperfusion. Mice received apocynin (2.5 mg.kg(-1), i.p.) either 0.5 h before ischaemia or 1 h after reperfusion. In situ superoxide production after cerebral ischaemia-reperfusion was measured in brain sections of wild-type mice at 24 h using dihydroethidium fluorescence.
Treatment with apocynin 0.5 h before ischaemia reduced total infarct volume, neurological impairment and mortality in wild-type but not Nox2(-/-) mice. Conversely, treatment with apocynin 1 h after initiation of reperfusion had no protective effect. Cerebral ischaemia and reperfusion increased superoxide production in the brain at 24 h, and pretreatment but not posttreatment with apocynin reduced superoxide levels.
Apocynin improves outcome following stroke when administered before ischaemia in wild-type but not Nox2(-/-) mice.
据报道，含Nox2的还原型烟酰胺腺嘌呤二核苷酸磷酸（NADPH）氧化酶活性产生的活性氧（ROS）在脑血管疾病中具有有害作用。然而，其他Nox亚型产生的ROS可能具有生理作用。目前尚未鉴定出Nox2选择性抑制剂，因此尚不清楚亚型非选择性Nox抑制剂是否必然能改善中风后的预后。我们评估了芹菜素对脑血管ROS产生的影响，以及在脑缺血前或脑再灌注后给予芹菜素对脑缺血后预后的影响。使用Nox2基因敲除（Nox2(-/-)）小鼠评估含Nox2的NADPH氧化酶在芹菜素作用中的参与情况。
通过大脑中动脉闭塞0.5小时，随后再灌注23.5小时诱导短暂性脑缺血。小鼠在缺血前0.5小时或再灌注后1小时接受芹菜素（2.5 mg·kg(-1)，腹腔注射）。在24小时时使用二氢乙锭荧光法测量野生型小鼠脑切片中脑缺血再灌注后的原位超氧化物产生。
在缺血前0.5小时用芹菜素治疗可减少野生型小鼠而非Nox2(-/-)小鼠的总梗死体积、神经功能缺损和死亡率。相反，在再灌注开始后1小时用芹菜素治疗没有保护作用。脑缺血和再灌注在24小时时增加了脑中的超氧化物产生，芹菜素预处理而非后处理可降低超氧化物水平。
在野生型而非Nox2(-/-)小鼠中，缺血前给予芹菜素可改善中风后的预后。
