局灶性脑缺血再灌注时诱导型一氧化氮合酶在大鼠脑组织的分布特点

目的观察大鼠脑缺血再灌注时诱导型一氧化氮合酶（inducible nitric oxide synthase，iNOS）在脑组织的分布特点，及其在缺血性脑损伤中的作用。方法阻断大鼠大脑中动脉（middle cerebral artery，MCA）血流2h。再灌注3-120h制成脑缺血再灌注模型。苏木精-伊红染色评价缺血性脑损伤的组织学特点，免疫组织化学（immunohistochemistry，IHC）染色观察iNOS在脑组织的分布特点。结果再灌注12h组开始出现神经元不可逆变性，24h梗死形成。正常组和假手术组、再灌注3h组无iNOS阳性的细胞。再灌注12～120h过程中，脑组织iNOS阳性细胞在再灌注12h开始表达，24h达到高峰，后逐渐下降。再灌注12～120h各组与正常组、假手术组、3h组比较P〈0．01。再灌注各组与24h组比较P〈0．01。结论iNOS在脑缺血再灌注后12h开始表达，24h达高峰，后逐渐下降，其细胞定位以小胶质细胞为主。iNOS与脑缺血再灌注后期神经元损伤有明显关联。为临床早期使用iNOS抑制剂减少脑损害，提供了一定的参考价值。

The distributive characteristics of inducible nitric oxide synthase (INOS) in cerebraltissue of rats subjected to cerebral ischemia-reperfusion

Objective To observe the distributive characteristics of inducible nitric oxide synthase（iNOS） in cerebral tissue of rats subjected to cerebral Ischemia-reperfusion, and its role in ischemic brain damage. Methods The model of focal cerebral ischemia was made by occluding middle cerebral artery （ MCA ） for 2h and reperfusion for 3 ～120h. HE staining was used to investigate the histological features of ischemic cerebral damage, the immunohistochemieal method was used to observe the expression of iNOS in brain tissue in rats. Results The neurons presented irreversible degeneration at 12h of reperfusion. At 24h,the ischemic area in the preoptic area, striatum and cortex developed into infarct form iNOS positive cells were not detected in normal and sham-operated and 3h of reperfusion rats. At 12,24,48,72,120h of reperfusion, the number of iNOS positived cells appeared at 12h of reperfusion, then peaked at 24h of reperfusion, and then gradually decreased. Quantitation analysis reveals that the number of iNOS immunoreactive cells in the ipsilateral-isehemic area significantly decreased （ P 〈 0.01 ） at 48,72h, and 120h after MCA occlusion reperfusion compared with that of 24 after MCA occlusion reperfusion. Moreover, the number of Inos immunostaining cell in ischemic area significantly increased （ P 〈 0.01 ） at 24h after MCA occlusion compared with that of control groups. Conclusion iNOS expression appears at 12h of reperfusion, peaked at 24h of reperfusion and then decreased gradually, mainly expressed in activated mieroglias or macrophages, iNOS had a siginificancy correlation to neuron injury in the late phase of cerebral isehemia reperfusion. The study provides a certain referance value to use iNOS inhibitor in early phase of cerebral ischemic to decrease cerebral injury.