沙土鼠短暂性脑缺血后海马CA1区细胞凋亡及亚低温的影响

目的：研究沙土鼠短暂性脑缺血后海马ＣＡ１区细胞凋亡及亚低温的治疗作用。方法：阻断沙土鼠双侧颈总动脉２０分钟造成前脑缺血模型。实验动物被随机分为假手术组、缺血－再灌注组、亚低温治疗组。海马ＣＡ１区的迟发性神经元死亡（ＤＮＤ）过程通过序列光镜观察进行研究,原位末端标记（ＴＵＮＥＬ）法用来检测死凶的ＤＮＡ片断。结果：短暂性脑缺血后,海马ＣＡ１区锥体神经元于再灌注后２～７日死亡。死亡锥体神经元的序列光镜观察没有发现早期的凋亡样改变,ＤＮＡ 断化也发生在ＤＮＤ出现之后。亚低温处理动物再灌注后２～７日,海马ＣＡ１区缺血性神经元死亡较常温处理动物显著减轻,再灌注后３～７日,海马ＣＡ１区ＤＮＡ片断化也显著减少。结论：缺血后的亚低温治疗产生了神经保护作用,而抑制神经元ＤＮＡ片断化的出现可能是其保护机制之一。

Apoptosis in hippocampal CA1 neurons and effect of moderate hypothermia after transient forebrain ischemia in gerbils

Objective To explorethe neuronal apoptosis in the hippocampal CA 1 region and effect of moderate hypothermiaafter transient forebrain ischemia i n gerbils. MethodsTransient forebrain ischemia wasinduced by 20 minutes bilat eral carotid occlusion.All gerbils were randomly divided intosham operation gr oup,ischemiareperfusion group and moderate hypothermia group.Delayedneuronal death (DND) in hippocampal CA1 region was studied by means of sequential lightmicroscopy examination.Fragmented DNA of dead neurons was identified by termina ldeoxynucleotidyl transferase nick endlabeling (TUNEL). ResultsTransient for ebrainischemia induced neuronal death in hippocampal CA1 region on days 27 af terreperfusion.Sequential light microscopic study of dead pyramidal neurons sho wed thatearly chromatin changes of apoptosis were absent and DNA fragmentation occurred after thedevelopment of DND in the CA1 region.Ischemic neuronal injur y was significantly reducedin hypothermic animals on days 27 after reperfusio n compared to the normothermicanimals.TUNEL examination revealed that there wer e much less DNA fragmentations inmoderate hypothemia group than that of ischemi areperfusion group. ConclusionsModeratehypothermia in postischemic period ca n provide protective effects by inhibiting DNAfragmentation in neurons.