头部重点低温对缺血后再灌注时兔脑神经元转归的影响

EFFECTS OF SELECTIVE HEAD COOLING ON NEURONAL OUTCOME DURING POST ISCHEMIA REPERFUSION IN RABBITS

探讨头部重点低温（ＳＨＣ）能否改善受损兔脑神经元的转归，以及相应的生化机制。方法：采用“四血管”模式造成脑缺血３０ｍｉｎ，然后将１６８只新西兰兔随机分为三组，Ⅰ组为未缺血对照组；其余两组动物的３个亚组均在缺血３０ｍｉｎ后分别再灌注３０、１８０和３６０ｍｉｎ；Ⅱ组为常温再灌注组；Ⅲ组为ＳＨＣ治疗组，开始再灌注时实施ＳＨＣ（２８℃）。检测了脑组织中２１项生化指标的变化和采用计算机图像分析技术，将１２个脑区的神经元分为Ａ（正常）、Ｂ（轻伤）、Ｃ（重伤）和Ｄ（坏死）四类。采用ＳＰＳＳ作相关分析和ｔ检验。结果：与Ⅰ组相比，Ⅱ组Ａ类神经元所占百分比在再灌注时进行性下降，Ｂ、Ｃ类明显增多，Ｄ类则进行性增多（均Ｐ＜０．０１）；与Ⅱ组相比，Ⅲ组Ａ类进行性增多，Ｂ类也增多；Ｃ、Ｄ类减少（均Ｐ＜０．０１）；Ⅱ组与Ａ类改变相关的生化指标是ＶＩＰ、β－ＥＰ、ＰＧＩ２、Ｔ３、Ｔ４和Ｎａ＋－Ｋ＋ＡＴＰ酶；与Ｂ类是β－ＥＰ和ＴＸＢ２；与Ｃ类是Ｇｌｎ、ＴＸＢ２／ＰＧＩ２；与Ｄ类是Ｔ４、Ｎａ＋－Ｋ＋ＡＴＰ酶、Ｇｌｎ、Ｔ３和ＶＩＰ（Ｐ＜０．０５）。Ⅲ组Ｃａ２＋－Ｍｇ２＋ＡＴＰ酶与Ａ、Ｃ和Ｄ类变化相关（Ｐ＜０．０５）。结论：ＳＨＣ确能改善受损神经?

To determine whether SHC(selective head cooling) can change the neuronal outcome, and explore the biochemical mechanism of its effects during postischemic reperfusion in rabbits. Complete cerebral ischemia (CCI) was induced by the“four vessel model”for 30 minutes. 196 New Zealand rabbits were randomly allocated into three groups: group 1 served as non ischemic control, animals in three subgroups of other groups had reperfused lasting 30, 180 and 360 minutes respectively following CCI, group 2 served as postischemic normothermic reperfusion, group 3 treated with SHC(28℃, cooling was iniated at the beginning of reperfusion). The changes of 21 biochemical parameters in brain were determined, and histomorphological assessments of neuronal changes were observed. Neurons of 12 regions were differentiated respectively into type A (normal), type B (mild damaged), type C ( severely damaged ) and type D ( necrotic). Correlate analysis and t test was done using SPSS. As compared with Group Ⅰ, the percentage of type A neurons was stepwisely decreased, while that of type B, C, D neurons increased significantly in group Ⅱ( P < 0.01), As compared with Group Ⅱ, type A and B neurons increased while type C and D decreased in group Ⅲ ( P < 0.01). In the group Ⅱ, the parameters correlated with the changes of type A neuron are VIP, β EP, PGI 2, T 3 , T 4 and Na + K + ATPase, that of type B are β EP and TXB 2, that of type C are Gln, TXB 2 /PGI 2, that of type D are T 4, Na + K + ATPase , Gln, T 3, and VIP ( P < 0.05). The parameters correlated with the changes of type A、C and D all were Ca 2+ Mg 2+ ATPase in the group Ⅲ( P < 0.05). Our results suggested that the selective head cooling do improve the outcome of neuronal. The main processes involved in these effects were salvaging a great of mildly damaged. The main biochemical mechanisms of these beneficial effects included: promoting the recruitment of membrane function and curtailing off the state of hypermetablism.