以往对缺血后脑内一氧化氮合成酶(NOS)表达变化的报道限于较晚的时间点上.由于缺血后海马神经元的死亡与再灌流早期的细胞内环境变化有关,因此缺血后海马内NOS表达的早期变化值得研究。实验选用体重200～300克的雄性SD大鼠,以Pnlsineui—Brierly四管闭塞模型缺血15分钟,于再灌流后0～2h、6h、12h、24h、3d、7d(n=3或4)分别给予4%多聚甲醛灌注固定,30min至40min灌完,后固定2h.假手术对照组于术后2h(n=3),6h(n=3);及正常对照组(n=4)按同样方法处理.冰冻冠状切片40μm,自海马灰质出现 In the past, the changes of the expression of nitric oxide synthase (NOS) in the brain after ischemia were limited to the later time points.As the death of hippocampal neurons after ischemia is related to the changes of intracellular environment in the early period of reperfusion, The early changes of NOS expression in hippocampus deserve to be studied. In the experiment, male Sprague-Dawley (SD) rats weighing 200-300 g were randomly divided into 4 groups: Pnlsineui-Brierly occlusion model for 15 minutes, and the rats were sacrificed at 0-2h, 6h, 12h, 24h, 3d and 7d after reperfusion (n = 3 or 4) (N = 3), 6h (n = 3); and normal control group (n = 4) after 2 hours of operation, Proceed in the same manner. Frozen coronal sections of 40 μm appear from the hippocampus gray matter