脑缺血及再灌流早期大鼠大脑皮质一氧化氮合酶表达的变化

目的　探讨脑缺血和再灌流早期一氧化氮合酶 (NOS)表达的变化。方法　选用体重2 0 0～ 3 50 g的雄性 SD大鼠 3 6只随机分为 6组 :假手术组、单纯脑缺血 15min、2 0 min、3 0 min组以及脑缺血 15min再灌流 3 0 min和 2 4h组。采用 4血管脑缺血动物模型 ,到期动物行 4%多聚甲醛灌注固定 3 0～ 40 min,取脑并后固定 3～ 4h,连续冠状冰冻切片 ,片厚 40μm,NOS组化染色显示 NOS,镜下观察计数 NOS阳性神经元以进行半定量分析。结果　对照组大脑皮质有一定量阳性神经元分布 ;单纯脑缺血早期 NOS表达呈“单峰”变化 ;脑缺血 15min再灌流早期 NOS表达呈“双峰”变化。结论　脑缺血早期和脑缺血再灌流早期 NOS表达变化不同 ,这可能是再灌流加重缺血神经元损伤的原因

Changes of NO synthase expression in cerebral cortex areas during the early phase of cerebral ischemia and ischemic reperfusion in rats

ObjectiveTo explore the changes of nitric oxide synt hase (NOS) e xpression during the early phase of cerebral ischemia and ischemic reperfusion. MethodsThirty-six male SD rats(200~350 g) were randomly divi ded into 6 groups: Sham-operated group, 3 groups of cerebral ischemia for 15 mi n,2 0 min and 30 min,respectively, and 2 groups of ischemia-reperfusion(IR) for 30 min and 24 h. The four-vessel occlusion ischemic model was performed with the m ethod of Pulsinlli-Brierly in this experiment. Animals were killed by transcardiac perfusion for fixation(30~40 min), and then their brains were remo v ed and postfixed for 3~4 h. Brain sections were obtain by cryostat sectioning. N O S-positive neurons in cerebral cortex areas were observed by optical microscope and calculated and analyzed semi-quantitatively. ResultsOnly a few NOS-positive neurons were seen in cerebral cortex areas at control groups; NOS expression was the single peak change at cer ebral ischemia groups or the double peak change at IR groups. ConclusionThe early phase of cerebral ischemia differs from th at of IR in the changing of NOS expression,and the difference might be one of th e cause that reperfusion ameliorate ischemic neuronal lesion.