运动对小鼠脊髓前角运动神经元树突结构可塑性的影响

HRP—CB标记结合sholl分析方法分析研究5、13、24月龄三个年龄组C57BL/6J小鼠脊髓前角α—运动神经元树突结构的可塑性变化,以及不同时间的长期适量运动(跑转笼)对运动神经元树突结构可塑性变化的可能作用。以同年龄对照组心重/体重比率均值的二倍标准差(X+2SD)做为运动有效标准。结果在三个年龄对照组中,老年鼠(对照组Ⅱ)神经元树突野缩小,树突分支数和总长度明显减少(P<0.05),以远离胞体的分支丢失为主。经过8和19个月运动训练后,脊髓前角运动神经元树突野扩大,分支数和树突总长度明显增加(P<0.01),甚至超过青年对照,以近胞体分支的增生更明显。结果表明,长期的适量运动能够延缓衰老过程中小鼠脊髓前角运动神经元树突的丢失,促进树突的可塑性增生。     

小鼠脊髓前角运动神经元的分离、培养和鉴定

目的:探讨一种分离小鼠脊髓前角运动神经元的方法,为运动神经元相关的研究提供依据。方法:分离13 d的C57BL/6胎鼠脊髓,利用Optiprep分离液经密度梯度离心获得脊髓前角运动神经元,培养后观察神经元细胞形态的变化,免疫荧光双标法对分离运动神经元的纯度进行判定。结果:将分离到的运动神经元进行培养,能够观察到典型的神经元细胞形态及轴突生长。免疫荧光双标证明培养的细胞为运动神经元细胞,纯度约95%。结论:Optiprep分离液用于小鼠运动神经元的分离,可获得良好的分选效果。Optiprep分离液可用于运动神经元相关的研究。     

急性马尾神经压迫后脊髓前角运动神经元细胞凋亡相关蛋白的表达规律

BACKGROUND: Cauda equina syndrome often induces skin hypoesthesia in the perineal area, poor urine-stool control, and impairs male function. After peripheral nerve fiber injury, apoptosis of neurons appeared. This is associated with the nature of the injury, the types of neurons, the species of animals, the age, and the distance between neurons. OBJECTIVE: To explore the motor neuron apoptosis and expression of apoptosis-associated protein in the anterior horn of the spinal cord after acute cauda equina compression.  METHODS: A total of 27 canines were randomly divided into three groups. In the compression and control groups, models of cauda equina compression were established. In the normal group, no models were established. Compression group received water sac compression for 4, 8, 12, 24, 48, 72 and 168 hours, with three models in each group. In the control group, only water sac was implanted, but water was not injected. Terminal deoxynucleotidyl transferase TdT-mediated biotin dUTP nick end-labeling assay was used to detect the apoptosis of neurons in the anterior horn of the spinal cord. Bcl-2, Bax and Caspase-3 protein expressions were measured by immunohistochemical staining (strept avidin-biotin complex). Gray values of positive cells of Bax, Bcl-2 and Caspase-3 protein expressions were detected using Qwin550Cw image collection and analysis system. RESULTS AND CONCLUSION: The apoptosis of motor neuron occurred in the compression groups. At 12 hours of compression, positive cells were detected, and the number of positive cells reached a peak at 72 hours. Bax and Bcl-2 protein expression was small in the normal group. Caspase-3 protein expression was not detected in the normal and control groups. Bax and Bcl-2 protein expression was significantly increased at 8 hours, peaked at 72 hours and reduced to a normal level at 168 hours. The increased range of Bax protein expression was bigger than that of Bcl-2. Caspase-3 protein began to express at 12 hours, peaked at 72 hours and reduced to a low level at 168 hours. Bax and Caspase-3 protein expression peaked at 72 hours, and Bcl-2 protein expression was not obviously increased. These findings verified that after acute cauda equina compression, the apoptosis of neurons occurred in the anterior horn of the spinal cord. Bax and Bcl-2 protein expression showed an antagonistic action. In the Bax/Bcl-2 complex, Bax protein in a high expression promoted apoptosis, induced Caspase-3 protein expression, and neuronal apoptosis.      

大鼠坐骨神经损伤后脊髓前角神经元死亡数量的研究

目的：研究周围神经损伤后，脊髓前角运动神经元胞体的死亡数量变化。方法：选择10只正常SD大鼠，先计算两侧的脊髓前角运动神经元胞体数量是否对称；再选择35只SD大鼠，切断并原位吻合其右侧坐骨神经，左侧不作任何处理、作为对照，于术后不同时间取L4～6节段脊髓作HE染色，计算脊髓前角运动神经元胞体数量的变化。结果：正常SD大鼠两侧的脊髓前角运动神经元胞体数量呈对称分布；右侧坐骨神经损伤后，其脊髓前角运动神经元胞体数量较左侧减少。结论：大鼠坐骨神经损伤后，脊髓前角运动神经元的胞体有死亡，其死亡具有一定的时间特征。     

Selective loss of alpha motor neurons with sparing of gamma motor neurons and spinal cord cholinergic neurons in a mouse model of spinal muscular atrophy

Spinal muscular atrophy (SMA) is a neuromuscular disease characterised primarily by loss of lower motor neurons from the ventral grey horn of the spinal cord and proximal muscle atrophy. Recent experiments utilising mouse models of SMA have demonstrated that not all motor neurons are equally susceptible to the disease, revealing that other populations of neurons can also be affected. Here, we have extended investigations of selective vulnerability of neuronal populations in the spinal cord of SMA mice to include comparative assessments of alpha motor neuron (α‐MN) and gamma motor neuron (γ‐MN) pools, as well as other populations of cholinergic neurons. Immunohistochemical analyses of late‐symptomatic SMA mouse spinal cord revealed that numbers of α‐MNs were significantly reduced at all levels of the spinal cord compared with controls, whereas numbers of γ‐MNs remained stable. Likewise, the average size of α‐MN cell somata was decreased in SMA mice with no change occurring in γ‐MNs. Evaluation of other pools of spinal cord cholinergic neurons revealed that pre‐ganglionic sympathetic neurons, central canal cluster interneurons, partition interneurons and preganglionic autonomic dorsal commissural nucleus neuron numbers all remained unaffected in SMA mice. Taken together, these findings indicate that α‐MNs are uniquely vulnerable among cholinergic neuron populations in the SMA mouse spinal cord, with γ‐MNs and other cholinergic neuronal populations being largely spared.     

大鼠周围神经移植修复后脊髓前角运动神经元变化的动态观察

目的　观察大鼠移植神经远侧吻合口再通术后脊髓前角细胞形态及功能变化,为长段神经移植后行远侧吻合口再通术提供理论支持。 方法　实验采用SD大鼠120只,随机分为6组,分别为：(1)神经单纯切断组;(2)神经切断缝合组;(3)神经移植修复组;(4)游离神经移植修复后远侧缝合口切除组;(5)游离神经移植修复后远侧缝合口切除再缝合组; (6)假手术组。术后1、2、4、8、12和16周取出脊髓腰膨大,进行组织学观察和免疫组化检测。 结果　实验组术后1周胞浆轻度水肿,线粒体肿胀,空泡化。术后2~4周,神经元超微结构的改变明显加重,术后4~8周进入恢复期。第3组术后1周,BDNF在运动神经元内表达开始增加,2周达到了高峰,8周下降。NGF的表达在术后2周开始上升, 8周达到高峰,之后持续下降。第5组BDNF的表达在术后8~16周期间呈上升趋势,NGF的表达在术后8周一直维持平稳状态,而对照组各时间段无明显变化。 结论　长段神经移植修复术后,适时行远侧吻合口切除重新吻合,既去除了远侧吻合口的瘢痕,同时再次激活神经元功能的状态,有利于功能恢复。     

The pattern of distribution of serotoninergic fibers in the anterior horn of the chick spinal cord

Summary The pattern of distribution of serotonin positive fibers in the motor nuclei of the chick spinal cord was examined immunohistochemically by using an antiserum against serotonin. A dense aggregation of serotoninergic fibers was located around anterior horn cells in the cervical spinal cord. In the brachial spinal cord, serotoninergic fibers were densely aggregated in the medial motor column and in the parts of the lateral motor column. There were two regions of serotonin immunoreactivity in the lateral motor column of the brachial spinal cord; one located in the ventromedial regions where a dense aggregation of serotoninergic fibers was found, and the reminder of the lateral motor column where only a few serotoninergic fibers were observed. The region containing a dense cluster of serotoninergic fibres around profiles of motoneuron somata and proximal dendrites appears to correspond to motor neuron pools of flexor muscles. In the thoracic spinal cord a high density of serotoninergic fibers was found in the motor nucleus. In the lumbosacral spinal cord (segments LS1–LS8) serotoninergic fibers were not observed in the medial motor column. However, there were five regions in the lateral motor column, where a high density of serotoninergic fibers was found. These very likely correspond to motor neuron pools of muscles which extend the hip joint.     

高压氧前处理脊髓损伤大鼠前角运动神经元的凋亡*☆

背景：脊髓损伤后难以修复,损伤后保护残存的神经元是促进神经再生的关键。 目的：验证高压氧预处理可以通过抑制早期的细胞凋亡来保护脊髓前角运动神经元。 方法：随机将26只雄性Wistar大鼠等分成模型组和实验组。实验组在给予高压氧5 d后与模型组同时制作脊髓T9~10全横断模型。 结果与结论：尼氏染色显示脊髓T9~T10全横断后8 h及1 d,脊髓前角的浓染的细胞多见,与模型组相比,实验组脊髓前角浓染的细胞较少。TUNEL染色也显示脊髓T9~T10全横断后脊髓损伤后8 h~1 d,2组大鼠脊髓前角内均可见大量的凋亡神经元,3 d时凋亡神经元数量减少。相比于模型组,高压氧预处理8 h,1 d后大鼠脊髓前角凋亡神经元较少(P < 0.05,        P < 0.01)。说明高压氧预处理能对脊髓损伤后前角运动神经元起保护作用。       

Somatotopic organization of lumbar muscle-innervating neurons in the ventral horn of the rat spinal cord

The ventral horn of the rat spinal cord was investigated with respect to the somatotopic organization of the motor neurons that innervate the lumbar muscles. Neurotracer 1,1′‐dioctadecyl‐3,3,3′,3′‐tetramethylindocarbocyanine perchlorate (DiI) was applied to specific sites in lumbar muscles. Spinal cord segments at L1 through L4 levels were cut into 40‐μm serial transverse sections. Labeled neurons were located in the ventromedial nucleus (VM) and lateromedial nucleus (LM) nuclei of Rexed’s lamina IX. Motor neurons innervating the m. interspinales lumborum and m. multifidus were without exception present in the VM, whereas all motor neurons innervating the m. rectus abdominis were present in the LM. Forty percent of motor neurons innervating the m. quadratus lumborum were present in the VM and the other 60% were in the LM. Although most of the motor neurons innervating the m. psoas major were present in the LM, a few labeled neurons existed in the VM. These results suggest that the border zone demarcating the areas of innervation of the dorsal and ventral rami of spinal nerves crosses the m. quadratus lumborum.     

睾酮对小鼠坐骨神经损伤后脊髓前角运动神经元的保护作用

目的探讨睾酮对坐骨神经损伤后脊髓运动神经元的保护作用。方法12只性成熟C57雄性小鼠随机分为:芝麻油对照组(n=6)和睾酮实验组(n=6)。采用单侧坐骨神经切断损伤模型,手术后分别隔日皮下注射芝麻油和睾酮。两周后通过尼氏染色统计腰骶髓坐骨神经损伤侧的前角运动神经元数量和截面积。结果睾酮实验组腰骶髓前角运动神经元状态要好于芝麻油对照组,胞体饱满,突起较多。神经元数量和平均截面积明显大于芝麻油对照组(P0.01)。结论坐骨神经损伤后,睾酮对支配该神经的运动神经元具有明显的保护作用,增加存活运动神经元的数量和截面积。     

GABA-immunoreactive neurons in the dorsal horn of the rat spinal cord

An antiserum to GABA was used on semithin resin-embedded sections of rat dorsal horn. Immunoreactive neurons were evenly distributed throughout laminae I-III and constituted between 24 and 33% of the total neuronal population within three laminae. Fifty Golgi-stained cells in lamina II were tested with the antiserum. Most of the islet cells examined were immunoreactive, although some small islet cells were not. None of the 14 stalked cells tested was immunoreactive. These results provide further evidence that the stalked and islet cells of lamina II form two distinct functional classes and suggest that the islet cells function as inhibitory interneurons.     

Four subtypes of motor neurons exhibiting mutually exclusive firing patterns in the spinal ventral horn

Motor neurons (MNs) communications are thought to occur primarily through spike bursts and regularly firing action potential trains. Reports of both burst and nonburst firing MNs suggest that these neurons may regularly fire in a variety of controlled output patterns with unique characteristics. Based on the cellular response to somatic current injection in these neurons, four distinct MN subtypes are identified from the spinal ventral horn. Approximately 42% of MNs exhibited regular firing, with minimal current injection (rheobase) exhibited a short latency, and with stronger current intensities exhibited significant spike frequency adaptation (SFA). Another 30% of MNs exhibited delayed onset at rheobase with a weakly-adapting firing pattern as stimulation increased. The remaining 18% and 10% of MNs exhibited transient firing patterns or exhibited irregular firing patterns when strongly depolarized, respectively. Our results provide a basis for improvement in the classification and study of MNs.