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目的:观察重度局灶性脑缺血状态下大鼠顶叶皮质一氧化氮合酶(NOS)表达过程,探讨NOS阳性神经元表达与脑血流量的关系。方法:SD大鼠随机分为5组即正常对照组,假手术组,脑缺血1、6、24h组。线栓法建立大鼠脑缺血模型,多排螺旋CT灌注成像测量脑血流量,采用还原型尼克酰胺腺嘌呤二核苷酸黄递酶(NADPH-d)法,观察脑血流量低于20%正常值时顶叶皮质NOS表达。结果:与对照组比较,缺血1h组顶叶皮质NOS阳性神经元数量明显增多;与对照组及缺血1h组比较,缺血6h组顶叶皮质NOS阳性神经元数量明显下降;与对照组及缺血1h组比较,缺血24h组顶叶皮质NOS阳性神经元数量进一步减少并几乎消失,与脑缺血6h组比较,无显著差异。当血流量仅轻度下降时,顶叶皮质NOS阳性神经元表达并无明显变化。结论:缺血侧脑血流量低于正常值20%时,顶叶皮质NOS阳性神经元在缺血1h时显著增加,缺血6、24h急剧减少;缺血后NOS阳性神经元表达,不仅与缺血持续时间有关,还与缺血程度有关。
Objective: To observe the process of nitric oxide synthase (NOS) expression in parietal cortex of rats with severe focal cerebral ischemia and to explore the relationship between the expression of NOS positive neurons and cerebral blood flow. Methods: SD rats were randomly divided into 5 groups: normal control group, sham operation group, cerebral ischemia 1, 6, 24 h group. The rat model of cerebral ischemia was established by thread occlusion method. The cerebral blood flow was measured by multislice spiral CT perfusion imaging. The reduction of cerebral blood flow was observed by NADPH-d method NOS expression in parietal cortex at% normal. Results: Compared with the control group, the number of NOS positive neurons in the parietal lobe cortex increased significantly 1 h after ischemia; compared with the control group and the 1 h ischemia group, the number of NOS positive neurons in the parietal cortex significantly decreased 6 h after ischemia; Compared with ischemic 1h group, the number of NOS positive neurons in parietal cortex of ischemic 24h group decreased further and almost disappeared, which showed no significant difference compared with 6h cerebral ischemia group. There was no significant change in the expression of NOS positive neurons in the parietal cortex when the blood flow decreased only slightly. CONCLUSION: NOS positive neurons in the parietal cortex increase significantly at 1 h after ischemia and decrease sharply at 6 h and 24 h after ischemic cerebral blood flow is less than 20% of normal. The expression of NOS positive neurons after ischemia is not only correlated with Ischemia related to the duration, but also with the degree of ischemia.