新生鼠脑损伤性神经变性的电镜观察(英文)

Electron microscopic observation on neurodegeneration induced by brain injury in newborn rats

背景:由于儿童脑的发育尚未成熟,加上血脑屏障发育不完善,临床处理不当将影响其生长发育。对未成熟脑损伤性神经变性的进一步研究是十分必要的。目的:通过建立新生7dSD大鼠顶叶皮质脑挫伤动物模型,观察大鼠同侧顶叶皮质和海马神经细胞的超微结构。设计:完全随机对照实验。单位:上海交通大学医学院神经形态实验室和细胞生物学实验室以及中科院上海生理研究所电镜室。材料:实验于2002-10/2003-06在上海第二医科大学(现称上海交通大学医学院)解剖教研室神经形态实验室、细胞生物学实验室以及中科院上海生理研究所电镜室完成。19只新生7dSD大鼠,随机分为实验组15只、手术对照组2只和正常对照组2只。方法:实验组用自由落体脑外伤装置建立新生7dSD大鼠顶叶皮质脑挫伤动物模型。手术对照组除无自由落体重力锤撞击外,麻醉、头部皮肤切开等操作与实验组相同。正常对照组动物不做任何处理。经常规电镜处理,于透射电镜下观察细胞结构的变化。主要观察指标:各组大鼠同侧顶叶皮质和海马神经细胞超微结构观察。结果:19只大鼠均进入结果分析。①电镜下,实验组神经元有两种类型的形态改变。其一为神经元树突和胞体呈巨大膨胀,伴随着细胞器的改变。早期内质网池扩大,线粒体致密和浓缩。此后内质网空泡化,线粒体进行性肿、胀和空泡化,多聚核糖体从粗面内质网上解离,并散在于胞浆中,核的改变出现于胞浆改变明显之后。核染色质由簇状集聚于核膜下呈钟面排列到向中央积聚成轮廓不规则的团块。轴突基本正常。变化二为胞浆和胞核均浓缩,胞浆中有大小不等的空泡。②手术对照组和正常对照组同侧顶叶皮质和海马细胞均无异常改变。结论:脑损伤后脑细胞肿胀、胞浆和胞核均浓缩,对未成熟脑创伤性神经变性起十分重要的作用。

BACKGROUND： As a result of immature brain of children and their imperfect blood brain barrier, improper clinical treatment would affect growth and development of children. It is fully important to perform further investigation on immature brain injury induced neurodegeneration. OBJECTIVE： To observe the uhramicrostructure of neurons in homolateral parietal cortex and hippocampus in newborn 7-day SD rat with contusion of parietal cortex. DESIGN： Completely randomized controlled trial. SETTING： Laboratories of Nerve Morphology and Cytobiology, Medical College of Shanghai Jiaotong University; Electron Microscope Room of Institute for Physiology, Chinese Academy of Science. MATERIALS： The experiment was performed in Teaching and Research Section of Anatomy, Laboratories of Nerve Morphology and Cytobiology of Shanghai Second Medical University （Medical College of Shanghai Jiaotong University; Electron Microscope Room of Institute for Physiology of Chinese Academy of Science from October 2002 to June 2003. A total of 19 newborn 7-day SD rats were randomly divided into experimental group, operation control group and normal control group with 15, 2 and 2 in each group respectively. METHODS： In experimental group, free-fall device for brain injury was used for establishing model of contusion of parietal cortex in newborn 7- day SD rat. Anesthesia and scalp incision were conducted, without using free-fall device in operation control group. But above procedures were not carried out in normal control group. The changes of uhramicrostructure were observed under transmission electron microscope after routine treatment of electron microscopic samples. MAIN OUTCOME MEASURES： UI of neurons in homolateral parietal cortex and hippocampus. RESULTS： All the 19 rats entered results analysis. ① There were two sorts of morphological changes in neurons in experimental group. One was evident swelling of dendrites and bodies of neurons, accompanied with the changes of organelles. In the early stage, expansion of endoplasmic reticulum cisterna could be observed and mitochondria became compact and concentrated. Then, vacuolization of endoplasmic reticulum, progressive swelling and vacuolization of mitochondria, dissociation of polysomes from rough endoplasmic reticulum and scattering of them in cytoplasm could be seen. Changes of nucleolns presented after significant changes of cytoplasm. Nuclear chromatin clustered together under karyotheca and arranged as clockface, which were some masses with irregular contours gathering to the center. Axons were almost normal. The other was concentration of cytoplasm and nucleolus with vacuolizations of unequal size in cytoplasm. ② There was no abnormal change in neurons in homolateral parietal cortex and hippocampus both in operation control group and normal control group. CONCLUSION： Swelling of brain cell and concentration of cytoplasm and nucleolus after brain injury play important roles in brain injury-induced neurodegeneration of immature rats.