适度运动对周围神经损伤后脊髓突触可塑性变化的作用研究

发布时间：2018-05-04 05:18

本文选题：坐骨神经损伤 + 脊髓前角运动神经元　；参考：《第二军医大学》2015年博士论文

【摘要】：[研究背景]外周神经损伤后可导致中枢神经系统(CNS)环路发生广泛的变化。在全球每年成千上万例的外周神经损伤病例中,只有不到10%的病人可以完全地恢复功能。外周神经损伤后,在相应的运动神经元胞体以及树突周围所投射的突触会发生大量退行性改变,这种现象被称为“突触剥离”。一般来说,突触剥离是是不可逆的,即使外周轴突成功地发生了再生或者肌肉纤维的再支配效应发挥了作用。突触剥离,或者说突触的退行性改变,被公认为是临床上功能恢复差的重要原因。能影响突触剥离的治疗可以改善外周神经损伤后的功能恢复。在本实验中,我们主要是研究作为一种可能的治疗方法,适度运动在突触剥离和退行性改变中的作用及其机制。运动,对突触剥离有十分显著的作用。如果完全离断小鼠坐骨神经,同时让小鼠接受两周左右的适度跑步运动,突触剥离和退行的现象会发生消失。基于此项预实验研究,我们假设适度运动可以影响外周神经损伤后脊髓环路中的脊髓可塑性。我们在本研究中,就是想进一步探讨现象背后的机制,试图通过设计的实验来进一步阐述原理。突触剥离是很多神经退行性疾病早期的一个重要标志。在很多中枢神经系统退行性疾病中(诸如阿尔茨海默病、帕金森综合症、亨廷顿舞蹈症等),投射在中枢神经元周围的突触发生了广泛地剥离。这些突触退行性改变的机制已被大量研究,且提出了不少可能的理论。因此,诸如可以影响外周神经损伤后的突触剥离现象的适度运动作为一种类似的治疗方法,是否存在着和中枢神经系统神经元退行性改变相类似的机制呢?这都有待本实验的进一步研究。[目的](1)观测坐骨神经横断损伤后,投射在脊髓前角运动神经元周围突触的表达情况；设计各实验组,探讨坐骨神经损伤后,适度运动对突触剥离现象及突触退行性改变的影响；(2)选取不同基因型小鼠,分别是野生型小鼠(WT)、运动神经元脑源性神经营养因子(BDNF)敲除型(BDNF KO)小鼠,观察BDNF在运动对坐骨神经横断伤后突触恢复再生过程中的具体作用及相关机制；(3)选取不同基因型小鼠,分别是野生型小鼠(WT)、RNA结合蛋白ZBP-1敲除型(ZBP1 KO)小鼠,观察ZBP1在运动对坐骨神经横断伤后突触恢复再生过程中的具体作用；[方法] (1)建立小鼠坐骨神经横断伤模型；(2)向小鼠腓肠肌和胫骨前肌注射荧光标记的霍乱毒素以逆行标记运动神经元；(3)比较不同组小鼠术后脊髓前角运动神经元周围投射的突触的表达情况(分别是完整的野生型小鼠、坐骨神经损伤+不运动组、坐骨神经损伤+持续两周跑步运动组),取L3-L5段脊髓行行系统连续冰冻切片；(4)比较不同组小鼠术后脊髓前角运动神经元周围投射的突触的表达情况(分别是完整的野生型WT小鼠、BDNF KO组、WT坐骨神经损伤+不运动组、WT坐骨神经损伤+持续两周跑步运动组、]BDNF KO坐骨神经损伤+不运动组、BDNF KO坐骨神经损伤+持续两周跑步运动组),取L3-L5段脊髓行行系统连续冰冻切片；(5)比较不同组小鼠术后脊髓前角运动神经元周围投射的突触的表达情况(分别是完整的野生型WT小鼠、ZBP1 KO组、WT坐骨神经损伤+不运动组、WT坐骨神经损伤+持续两周跑步运动组、ZBP1 KO坐骨神经损伤+不运动组、ZBP1 KO坐骨神经损伤+持续两周跑步运动组),取L3-L5段脊髓行行系统连续冰冻切片；[结果] (1)外周神经损伤后,投射在运动神经元周围的突触数目会显著性下降,突触会发生较大程度的剥离和退行性的改变；适度运动,可以使外周神经损伤后的运动神经元周围投射的突触修复再生,从而抑制外周神经损伤后脊髓背角运动神经元周围突触剥离和退行；(2)缺乏BDNF,适度跑步运动不能促进损伤的运动神经元周围的突触修复再生；神经元性的BDNF在受损伤的运动神经元周围突触修复再生发挥重要作用；胶质源性的BDNF也参与了受损运动神经元周围突触修复再生过程；(3)初级感觉神经元DRG中轴突蛋白ZBP-1的合成与运输参与了适度运动对投射在损伤运动神经元周围的突触剥离的影响；在RNA结合蛋白ZBP-1基因敲除小鼠上,运动不能导致受损伤运动神经元周围投射的突触修复再生；BDNF结合特异性TrkB受体激活下游信号转导通路在适度运动对外周神经离断损伤后脊髓突触修复再生过程中发挥了十分重要的作用；[结论]外周神经损伤后,投射于脊髓背角运动神经元周围的突触发生了显著性的剥离和退行性改变。适度运动可以使投射于外周神经损伤后运动神经元周围的突触大量修复再生；神经元脑源性神经营养因子(BDNF)是突触修复再生中的一个必须具备的分子,这种作用很有可能是BDNF与其TrkB受体结合激活下游信号转导通路以及通过合成RNA结合蛋白ZBP-1来实现的。以上这些研究结果均为临床上治疗周围神经损伤病人、加速患者的功能恢复提供了一定的理论依据。
[Abstract]:In this study , we hypothesized that moderate exercise can affect the spinal cord plasticity in the spinal cord after peripheral nerve injury .
To investigate the effects of moderate exercise on synaptic cleft and synaptic degeneration following sciatic nerve injury .
( 2 ) To observe the specific effects of BDNF in the regeneration of synaptic recovery after the sciatic nerve transection and the related mechanism in mice with different genotypes ( WT ) , brain - derived neurotrophic factor ( BDNF ) knockout ( BDNF KO ) mice , respectively .
( 3 ) The mice of different genotypes were selected as wild type mouse ( WT ) , RNA binding protein ZBP - 1 knockout type ( ZBP1 KO ) mice , and the specific effect of ZBP1 in the regeneration process of synaptic recovery after sciatic nerve transection injury was observed .
Methods : ( 1 ) To establish a model of sciatic nerve transection injury in mice ;
( 2 ) injecting a fluorescent labeled cholera toxin into the muscle and the anterior tibial muscle of the mouse to reversely sign the motor neuron ;
( 3 ) To compare the expression of synaptic transmission around the spinal cord anterior horn motor neurons in different group of mice ( complete wild type mouse , sciatic nerve injury + non - sports group , sciatic nerve injury + continuous two weeks running group ) , and take L3 - L5 spinal column system continuous freezing section ;
( 4 ) To compare the expression of synaptic expression around the spinal cord anterior horn motor neurons in different groups of mice ( complete wild type WT mice , BDNF KO group , WT sciatic nerve injury + non - exercise group , WT sciatic nerve injury + continuous two weeks running exercise group , BDNF KO sciatic nerve injury + non - sports group , BDNF KO sciatic nerve injury + continuous two weeks running exercise group ) , taking L3 - L5 segment spinal column system continuous freezing section ;
( 5 ) To compare the expression of synaptic transmission around the spinal cord anterior horn motor neurons in different groups of mice ( complete wild type WT mice , ZBP1 KO group , WT sciatic nerve injury + non - sports group , WT sciatic nerve injury + continuous two weeks running group , ZBP1 KO sciatic nerve injury + non - sports group , ZBP1 KO sciatic nerve injury + continuous two weeks running exercise group ) , taking L3 - L5 segment spinal column system continuous freezing section ;
Results : ( 1 ) After the peripheral nerve injury , the number of synaptic projections projected around the motor neurons decreased significantly , and there was a greater degree of exfoliation and degeneration of the synaptic potential .
moderate exercise can regenerate the synaptic repair around the motor neuron after peripheral nerve injury so as to inhibit synaptic exfoliation and retrogression around the motor neurons of the spinal dorsal horn after peripheral nerve injury ;
( 2 ) Lack of BDNF , moderate running does not promote the regeneration of synaptic repair around the injured motor neuron ;
The neuronal BDNF plays an important role in the regeneration of synaptic repair around the injured motor neuron ;
BDNF is also involved in the regeneration process of synaptic repair around damaged motor neurons .
( 3 ) The synthesis and transport of the axons protein ZBP - 1 in the DRG of primary sensory neurons were involved in the effects of moderate exercise on synaptic exfoliation around the injured motor neurons ;
In RNA - binding protein ZBP - 1 knockout mice , the movement could not lead to the regeneration of synaptic repair around the injured motor neurons ;
BDNF - specific TrkB receptor - activated downstream signal transduction pathway plays a very important role in the regeneration of synaptic cleft in the spinal cord after moderate exercise .
Conclusion After the peripheral nerve injury , there was a significant change of exfoliation and degeneration around the motor neurons in the dorsal horn of the spinal cord . Moderate exercise could regenerate the synaptic mass around the motor neuron after the peripheral nerve injury .
The neurotrophic factor ( BDNF ) is a necessary molecule in the regeneration of synaptic repair , which is likely to be achieved by combining BDNF with its TrkB receptor to activate the downstream signal transduction pathway and by synthesizing RNA binding protein ZBP - 1 . All of these findings provide a theoretical basis for clinical treatment of patients with peripheral nerve injury and accelerating the functional recovery of patients .

【学位授予单位】：第二军医大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：R745

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