大鼠脑缺血时血与脑中一氧化氮、超氧化物歧化酶和丙二醛含量的变化

目的探讨一氧化氮（ＮＯ）、超氧化物歧化酶（ＳＯＤ）和丙二醛（ＭＤＡ）在急性脑缺血时血与脑中的含量变化及其作用。方法４６只Ｗｉｓｔａｒ大鼠分为假手术组和缺血组。假手术组颈部正中切口，分离两侧颈总动脉；缺血组，结扎大鼠双侧颈总动脉，对缺血不同时相血清、脑皮层和丘脑组织中的ＮＯ、ＳＯＤ和ＭＤＡ含量进行测定。结果大鼠脑缺血１０分钟血清、脑组织ＮＯ浓度增高，３０分钟血清和脑组织中ＮＯ浓度最高，于６０分钟血清和脑组织中ＮＯ浓度下降至脑缺血１０分钟时的水平；而缺血１８０分钟血清和脑组织中ＮＯ浓度最低，并于３６０分钟后血清和脑组织中ＮＯ浓度回升，且较对照组升高但无显著性差异（Ｐ＞０．０５）。脑缺血１０，３０与６０分钟大鼠血清、脑组织中ＮＯ显著高于对照组（Ｐ＜０．０１和Ｐ＜０．００１）。脑缺血３０，６０，１８０与３６０分钟，大鼠ＳＯＤ活力显著低于对照组（Ｐ＜０．０５，Ｐ＜０．０１和Ｐ＜０．００１）；而ＭＤＡ显著高于对照组（Ｐ＜０．０５，Ｐ＜０．０１和Ｐ＜０．００１）。结论脑缺血时间越长ＳＯＤ酶活力越低而ＭＤＡ含量越高，长时间将大量产生释放具有神经毒性及细胞毒性作用的ＮＯ，可引起神经元死亡及细胞和组织损伤。

Changes of nitric oxide,superoxide dismutase and malondialdehyde in the blood and brain of rats during cerebral ischemia

Objective To study the changes of nitric oxide(NO),superoxide dismutase (SOD) and malondialdehyde(MDA) in the blood and brain of rats during cerebral ischemia and their action mechanisms. Methods 46 Wistar rats were randomly divided into the ischemia and control groups.The ischemia model of rats was established by bilateral ligation of common carotid artery and the control group of rats was given sham operation.The No,SOD and MDA concentrations in the blood serum and different regions of the brain were measured in both control and ischemia groups at 10,30,60,180 and 360 min after the operation. Results In the ischemia groups,NO concentrations of the serum and brain tissue were significantly increased at 10,30 and 60 min as compared with that before the operation(P<001 and P<0001).The No concentrations in the serum and brain tissue of the ischemia rats began to increase within 10 min after the onset of cerebral ischemia and were highest at 30 min and then returned to the same level as that of 10 min at 60 min.However,at 180 min,the No level was the lowerst;then 360 min,it elevated again and was slightly higher than that of the control group(P>005).Significantly low SOD activity and high MDA level were observed in the ischemia group at 360 min.Conclusions The longer the ischemia,the lower the SOD activity and the higher the MDA content will be.The excessive production of NO which participates in lipid peroxidiation,might be cytotoxic and neurotoxic,is deleterious to the cerebral cells and brain function.