脑缺血及再灌流早期大鼠海马CA_1区一氧化氮合酶表达的变化

目的　探讨脑缺血和再灌流早期大鼠海马CA1区一氧化氮合酶 (NOS)表达的变化。方法　选用体重 2 0 0～ 35 0g的雄性SD大鼠随机分为 6组 :假手术对照组、单纯脑缺血 15min、2 0min、30min组以及脑缺血 15min再灌流 30min和 2 4h组 ,参照Pulsinelli-Brierley法制作全脑缺血动物模型。 4 %多聚甲醛灌注固定 30～ 4 0min ,取脑并后固定 3～ 4h ,连续冠状冰冻切片 ,片厚 4 0um ,NADPH -d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　对照组海马CA1区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 NOS expression in rats hippocampal CA1 areas during early phase of cerebral ischemia and ischemic reperfusion

Objective To explore the changes of NOS expression during the early phase of cerebral ischemia and ischemic reperfusion. Methods Male SD rats(200～350?g) were randomly divided into 6 groups: psuedo-operative control group, cerebral ischemia 15?min/20?min/30?min, cerebral ischemic 15?min reperfusion 30?min and 24?h groups. The four-vessel occlusion ischemic model was performed with the method of Pulsinlli-Brierly in this experiment. Animals that did not meet these criteria of the succeeding model were excluded. Animals were killed by transcardiac perfusion for fixation(30～40?min), and then their brains were removed and postfixed for 3~4h. Brain sections were obtained by cryostat sectioning. NOS-positive neurons in hippocampus CA1 areas were observed by optical microscope and calculated and analyzed semi-quantitatively.Results Only a few NOS-positive neurons were seen in hippocampus CA1 areas at control groups; NOS expression is the "single peak" change at cerebral ischemic groups or the "double peak" change at ischemic reperfusion groups.Conclusions The early phase of cerebral ischemia differs from that of ischemic reperfusion in the change of NOS expression. The present findings demonstrate that the difference might be one of the causes that result in reperfusion ameliorate ischemic neuronal lesion.