深低温停循环下不同脑保护方法对海马区神经细胞凋亡及bcl-2、bax基因mRNA表达的影响

Effect of different cerebral protection methods under deep hypothermia circulatory arrest on neuron apoptosis and the expressions of mRNA of bcl- 2 and bax in hippocampus

目的:观察深低温停循环下给予不同脑保护方法后犬海马组织中神经细胞凋亡情况,探讨其对凋亡相关基因bcl-2和bax的mRNA表达的影响。方法:健康成年杂种犬(18～22kg)18只,随机分成3组,深低温停循环(deephypothermiacirculatoryarrest,DHCA)组(A组,对照组);DHCA+间断选择性顺行脑灌注(intermittentselectiveantegradecerebralperfusion,ISACP)组(B组);DHCA+逆行脑灌注(retrogradecerebralperfusion,RCP)组(C组)。术后取出海马组织,分别采用电镜和逆转录聚合酶链反应(RT-PCR)检测海马组织神经细胞凋亡情况及凋亡相关基因bcl-2和bax的mRNA表达情况。结果:电镜下,A组可见明显神经细胞凋亡改变,B、C两组仅见少量神经细胞凋亡改变。bcl-2mRNA在B组表达最高(P<0.01),C组表达明显高于A组(P<0.01);baxmRNA在A组表达最强(P<0.01),B组和C组间差异无显著性(P>0.05)。结论:DHCA下,给予ISACP或PCR两种脑保护方法都可以上调bcl-2mRNA的表达,但前者优于后者;两种脑保护方法也可以下调baxmRNA的表达,但二者间差异无显著性。

Objective To observe different methods of cerebral protection for the neuron apoptosis of hippocampus in dogs under deep hypothermia circulatory arrest and to investigate their effects on the mRNA expression of the apoptotic gene bcl-2 and bax. Methods Eighteen healthy adult dogs（18 - 22 kg）were randomly divided into three groups（6 dogs in each group）. The dogs in group A（control group）received deep hypothermia circulatory arrest（DHCA）. The dogs in group B received intermittent selective antegrade cerebral perfusion（ISACP） under DHCA. The dogs in group C received retrograde cerebral perfusion （PCP）under DHCA. After three procedures, the hippocampus tissues were removed immediately. The mRNA expression of bcl-2 and bax was detected by reverse transcription-polymerase chain reaction（RT-PCR）. Neuron apoptosis in the hippocampus tissues was examined under transmission electron microscopy（TEM） . Results The neuron apoptosis of hippocampus in group A was much more significant than that in group B and C. The level of expression of bax mRNA in group A was higher than that in group B and C （ P 〈 0. 01 ）, but there was no difference between group B and C （ P 〉 0. 05 ）. The level of bcl-2 mRNA expression in group C was much higher than that in group A, while that in group B was the highest among the three groups （ P 〈 0. 01 ） . Conclusions Both ISACP and PCP can up-regulate the expression of bcl-2 mRNA under DHCA, and ISACP is better. They can also down-regulate the expression of bax mRNA.