【作者】 吴春云；

【导师】 郭泽云； 于建云；

【作者基本信息】 昆明医学院 ， 人体解剖学与组织胚胎学， 2004， 硕士

【摘要】 目的：观察脑震荡(brain concussion，BC)大鼠轴索、髓鞘及多巴胺能神经元、神经纤维变化的规律，探讨BC大鼠认知行为障碍的特点及其与轴索、髓鞘和多巴胺能神经变化的关系，以了解脑震荡鼠认知行为障碍的神经生物学基础。方法：应用金属单摆打击装置复制大鼠BC模型，随机分为伤后1、2、4、8、16、24天组，共六个损伤组(每组n=12)。正常对照组(n=12)。用Morris水迷宫(Morris water maze，MWM)实验评价大鼠的学习记忆能力；用组织化学方法显示BC大鼠脑干轴索、髓鞘的变化；用鼠抗TH和鼠抗DBH单克隆抗体行免疫组化S-P法染色，联合标记以显示中脑黑质致密区、腹侧被盖区多巴胺神经元，基底节和前额叶皮质多巴胺神经纤维的变化。结果：8天组伤后1、2、3天大鼠隐匿平台逃避潜伏期与对照组相比显著延长(p＜0.05)。16、24天组行为学测试结果与对照组比较无显著性差异。BC后各组轴索均不同程度出现类似弥漫性轴索损伤(diffuse axonal injury，DAI)的病变，除24天组外，其他各损伤组与对照组比较均有显著性差异。病变以伤后2、4天组最重，8天后有所减轻，24天组基本恢复正常。髓鞘染色显示伤后各组均不同程度出现髓鞘肿胀、变性，与对照组比较均有显著性差异。病变以伤后2、4天组最重，8天后有所减轻，16、24天组明显减轻，但均未恢复到正常水平。中脑黑质致密区、腹侧被盖区、基底节免疫组化染色均显示，BC后1天组，TH免疫反应阳性显著高于对照组，4天组反应最强，8天后有所减弱，至24天，黑质致密区和基底节基本恢复正常，但腹侧被盖区仍高于对照组(p＜0.01)。前额叶皮质BC后2天组，TH免疫反应阳性纤维屠男医学脂研谈.研男空讼戈‘的密度和强弱显著高于对照组，4天组反应最强，8、16、24天组与4天组相比有所减弱，但比对照组仍显著增高。以上各部位免疫组化DBH反应均为阴性。结论:1.脑震荡后大鼠出现近期空间学习记忆功能障碍。2.脑震荡后大鼠脑干轴索和髓鞘均不同程度出现类似DAI的病理改变，与认知功能障碍有一定关系。3.脑震荡后黑质纹状体系统和中脑边缘皮质系统TH表达增高，推测TH早期增高可能是脑损伤后神经元一过性过度兴奋所致的神经递质紊乱，这种紊乱可能影响大鼠的认知功能。随后持续增高一段时间可能是多巴胺能神经元上调其合成能力的一种代偿反应，以增加多巴胺神经传递的效率。更多还原

【Abstract】 Objective: To observe the changes of axons, myelin sheath, dopaminergic neuron and nerve fiber, to study the feature of cognitive behavioral deficits in brain concussion(BC) rats, to explore the relationship between cognitive deficits and pathologic changes of axons, myelin sheath and dopaminergic system so as to know the neurobiologic mechanisms of cognitive behavioral deficits post BC in rats. Method : Animal model of concussive brain injury in rats was duplicated with a metallic pendulum-striker concussive device. Animals subjected BC were divided into 6 groups (n=12 in each group) :the group of 1d, 2d, 4d, 8d, 16d and 24d post-concussive injury. There were 12 normal rats acting as a control group. Learning and memory ability were assessed with Morris water maze(MWM) method. Histochemistry technique was used to show the morphological changes of axons and myelin sheath in brain stem. Tyrosine hydroxylase(TH) and dopamine-β-hydroxylase(DBH) levels were examined by immunohistochemistry S-P method in substantia nigra pars compact ( SNC) , ventral tegmental area (VTA), basal ganglia and prefrental cortex. Result: The escape latencies were longer statistically compared to the control group on days 1~3 post-concussion in 8d group (p< 0.05) . Within the 16 or 24d groups, MWM test was not significantly relative to the controls. The various morphological changes could be observed in all injured rats in the brain stem axons. With the exception of 24d group, all injured groups were different statistically compared to the controls. The damage of axons were more seriously at 2d and 4d groups than any other group. The severityof axonal lesion was attenuated after 8 days, and recovered in 24d group. The pathological changes could be finded in all injured rats in the brain stem myelin sheath. All BC groups were different significantly compared to the control group.The degeneration of the myelin sheath in 2d and 4d groups was more seriously .which could be relieved obviously in 16 and 24d groups. A increase in TH-immunoreaction(TH-IR) was observed significantly in the SNC, VTA and basal ganglia following 1 day post-concussive . The most significant change occured at 4d group. The expression of TH-IR had a descending tendency in 8d, 16d group compared to 4d group, and recovered in 24d group in SNC and basal ganglia, but the TH-IR still increased significantly relative to the control group in VTA. The density and intensity of the TH-IR in prefrontal cortex increased statistically in 2d, 4d groups post brain concussion. Though a descending tendency in TH-IR could be observed following 8, 16, 24d groups relative to 4d group , the density and intensity of TH-IR remained at a high level in prefrontal cortex compared to the control group (p< 0.01 ) . The immunologic reactions of DBHwere negative in all experiments. Conclusion: 1. Brain concussion injury has impaired effects on spacial learning and memory in rats in short term post-concussion. 2. The morphological pathological changes of the axons and myelin sheath were observed in BC brain stem similar to DAI, which may be correlated with cognitive behavioral deficits post brain concussion in rats. 3. The expression of TH-IR increased following BC. We speculate that the increase in TH in earlier period may be caused by neuronal transient overexcitation following post brain concussion , and the increase in TH remainded a period of time which may reflect a compensatory response of dopaminergic neurons to upregulate their synthesizing capacity in order to increase the efficiency of dopamine neurotransmission.更多还原