Pathophysiology and treatment for the acute phase of ischemic cerebrovascular disease

过氧亚硝酸盐已被证明是体内硝化的原因，而髓过氧化物酶（MPO）也可以在高NO2-水平的情况下催化蛋白质硝化。最近报道的MPO介导的酶失活或脂质过氧化表明MPO在各种病理条件下的作用。作为本项目的第一项研究，我们测量了MPO缺乏或野生型小鼠在2小时局灶性脑缺血再灌注后的硝基酪氨酸形成和梗死体积，以阐明MPO在缺血脑损伤中的作用。再灌注24h后，mpo缺陷小鼠的梗死面积明显大于野生型小鼠（81±20 mm3比52±13 mm3， p<0.01），梗死区硝基酪氨酸水平mpo缺陷小鼠明显高于野生型小鼠（13.4±6.1比9.8±4.4 μg/mg, p=0.13）。再灌注14h时，mpo缺陷小鼠的硝基酪氨酸水平明显高于野生型小鼠（3.3±2.9比1.4±0.4 μg/mg, p<0.05）。我们得出结论，MPO的缺失增加了体内缺血性神经元损伤，MPO介导的途径不是脑缺血再灌注中硝化反应的原因。此外，人们对溶栓的益处广泛感兴趣，但对再灌注损伤的关注却很少。本项目第二项研究的目的是评估永久性和短暂性局灶性缺血大鼠硝基酪氨酸形成和梗死面积的差异。在双侧颈总动脉永久性结扎的情况下，永久性或2小时阻断大脑中动脉分别诱导永久性（n=14）或短暂性（n=12）局灶性缺血。两种模型均在闭塞开始后24小时处死。短暂性局灶缺血时梗死笔区和梗死核心区硝基酪氨酸含量显著高于永久性局灶缺血时（p<0.01）。暂时性缺血时，脑皮层梗死面积（无论尾核还是全脑）均明显大于永久性缺血时（p<0.05），脑肿胀明显扩大。这些结果可能是由于再灌注导致超氧化物和一氧化氮的产生增加，并提示在治疗急性缺血性脑损伤时给予神经保护药物和溶栓药物的必要性。少

Peroxynitrite has been shown to be responsible for nitration in vivo, while myeloperoxidase (MPO) can also catalyze protein nitration in the presence of high NO2- levels. Recent reports of MPO-mediated enzyme inactivation or lipid peroxidation have suggested a role of MPO in various pathological conditions. As the first study in this project, we measured nitrotyrosine formation and infarct volume in MPO-deficient or wild-type mice subjected to 2-hour focal cerebral ischemia-reperfusion, to clarify the role of MPO in ischemia brain injury. Twenty-four hours after reperfusion, infarct volume in MPO-deficient mice was significantly larger than that in the wild- type mice (81±20 mm3 vs. 52±13 mm3; p<0.01), and nitrotyrosine levels in the infarct region showed a tendency to be higher in the MPO-deficient mice than in the wild-type mice (13.4±6.1 vs. 9.8±4.4 μg/mg; p=0.13). At 14 hours after reperfusion, the nitrotyrosine level was significantly higher in MPO-deficient mice, compared with th … More at in the wild-type mice (3.3±2.9 vs. 1.4±0.4 μg/mg; p<0.05). We conclude that the absence of MPO increases ischemic neuronal damage in vivo, and the MPO-mediated pathway is not responsible for the nitration reaction in cerebral ischemia-reperfusion.Furthermore, widespread interest in the benefit of thrombolysis has been discussed, but little attention has been paid to reperfusion injury. The purpose of the second study in this project is to evaluate the difference in nitrotyrosine formation and infarct volume between permanent and transient focal ischemia in rats. Permanent (n=14) or transient (n=12) focal ischemia was induced by permanent or 2-hour occlusion of the middle cerebral artery, respectively, with the permanent ligation of the bilateral common carotid arteries in Sprague-Dawley rats. All animals were killed at 24-hour after the start of occlusion in both models. The ratio of nitrotyrosine in the pen-infarct and core-of-infarct regions in transient focal ischemia was significantly higher than in permanent focal ischemia (p<0.01). Infarct volume in cortex, in neither caudoputamen nor whole brain, was significantly larger in transient ischemia than in permanent ischemia (p<0.05), with significant expansion of brain swelling. These results may be caused by the higher production of superoxide and nitric oxide owing to reperfusion, and suggest the necessity to administer neuroprotective drugs as well as thrombolytic agents in the treatment of acute ischemic cerebral damage. Less