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目的研究脑缺血预处理对沙鼠前脑缺血再灌注后热休克蛋白70(HSP70)表达水平及动物学习记忆能力的影响。方法100只蒙古沙鼠随机分成假手术(Sham)组、前脑缺血再灌注(I/R)组、脑缺血预处理(IP)组,放线菌酮+脑缺血预处理(Cycloheximide+IP)组,每组25只。后3组参照Kirino法制备前脑缺血动物模型,Kitagawa法制备脑缺血预处理动物模型。再灌注后1、2、3d取各组动物脑组织行H-E染色,观察海马CA1区神经元形态变化;用TUNEL法检测神经细胞凋亡情况;用免疫组织化学和蛋白质印迹法检测HSP70的表达水平。再灌注后3、4、5、6、7d用4-PTT旱路迷宫法对沙鼠的学习记忆能力进行评定,各取均值。结果与Sham组比较,I/R组沙鼠海马CA1区存活神经元密度降低(P<0.05),神经细胞凋亡数量增多(P<0.05),HSP70表达量增加(P<0.05),学习记忆能力下降(P<0.05);与I/R组比较,IP组中沙鼠海马CA1区存活神经元密度增加(P<0.05),凋亡神经细胞数量回降(P<0.05),HSP70表达水平进一步增加(P<0.05),学习记忆能力得到改善(P<0.05);而Cycloheximide+IP组基本消除了IP组中的上述改变,神经细胞形态及密度,神经细胞凋亡数量,HSP70表达水平、学习记忆能力与I/R组相似。结论缺血预处理对脑缺血性损伤具有保护作用并可改善脑缺血后的学习记忆功能障碍。这可能是通过促进HSP70表达增加,启动内源性的神经保护机制而加强了对再次缺血损伤的保护作用。
Objective To investigate the effect of cerebral ischemic preconditioning on heat shock protein 70 (HSP70) expression and animal learning and memory in the forebrain after forebrain ischemia in gerbils. Methods One hundred Mongolian gerbils were randomly divided into Sham group, I / R group, IP group, cycloheximide group and Cycloheximide + IP) group, 25 in each group. After 3 groups, the animal model of forebrain ischemia was established by Kirino method, and the animal model of cerebral ischemic preconditioning was prepared by Kitagawa method. At 1, 2 and 3 days after reperfusion, the brain tissue of each group was subjected to HE staining to observe the morphological changes of neurons in CA1 area of hippocampus; the apoptosis of nerve cells was detected by TUNEL method; the expression of HSP70 was detected by immunohistochemistry and Western blotting . 3, 4, 5, 6 and 7 days after reperfusion, the learning and memory ability of gerbils was assessed by 4-PTT dry-road maze method. Results Compared with Sham group, the neurons density of hippocampal CA1 subfield in I / R group decreased (P <0.05), the number of apoptotic neurons increased (P <0.05) and the expression of HSP70 increased (P <0.05) (P <0.05). Compared with I / R group, the density of surviving neurons in hippocampal CA1 region increased (P <0.05), the number of apoptotic neurons decreased (P <0.05), the expression of HSP70 (P0.05). Cycloheximide + IP group basically eliminated the above changes in IP group, the morphology and density of nerve cells, the number of apoptotic nerve cells, the expression level of HSP70, Learning and memory ability and I / R group similar. Conclusion Ischemic preconditioning has a protective effect on cerebral ischemic injury and can improve learning and memory dysfunction after cerebral ischemia. This may be through the promotion of HSP70 expression increased, the initiation of endogenous neuroprotective mechanisms and enhance the protection of reperfusion injury.