小鼠脊髓损伤后Nogo-A的免疫组织化学研究

目的研究小鼠脊髓损伤后Nogo-A的表达情况。方法 C57小鼠分为脊髓损伤组、假手术组和正常对照组,每组均在损伤后不同时间点（损伤后1 h,12 h,24 h）取材,然后行Nogo-A免疫组织化学染色。结果 Nogo-A明显表达于神经元胞体及其突起形成的神经纤维。随着损伤后存活时间的延长,Nogo-A阳性细胞数量和免疫反应强度均逐渐升高。结论脊髓损伤后24 h内Nogo-A在神经元的表达逐渐升高,导致神经再生困难。     

Mitochondrial health and muscle plasticity after spinal cord injury

European Journal of Applied Physiology - Mitochondria are responsible for aerobic respiration and large-scale ATP production in almost all cells of the body. Their function is decreased in many...     

Extensive spontaneous plasticity of corticospinal projections after primate spinal cord injury

Although axonal regeneration after CNS injury is limited, partial injury is frequently accompanied by extensive functional recovery. To investigate mechanisms underlying spontaneous recovery after incomplete spinal cord injury, we administered C7 spinal cord hemisections to adult rhesus monkeys and analyzed behavioral, electrophysiological and anatomical adaptations. We found marked spontaneous plasticity of corticospinal projections, with reconstitution of fully 60% of pre-lesion axon density arising from sprouting of spinal cord midline-crossing axons. This extensive anatomical recovery was associated with improvement in coordinated muscle recruitment, hand function and locomotion. These findings identify what may be the most extensive natural recovery of mammalian axonal projections after nervous system injury observed to date, highlighting an important role for primate models in translational disease research.     

Low-frequency H-reflex depression in trained human soleus after spinal cord injury

After spinal cord injury (SCI), widespread reorganization occurs within spinal reflex systems. Regular muscle activity may influence reorganization of spinal circuitry after SCI. The purpose of this study is to investigate the effects of long-term soleus training on H-reflex depression in humans after SCI. Seven subjects with acute (<7 weeks) SCI (AC group) underwent testing of H-reflex depression at several frequencies of repetitive stimulation. Eight subjects (including 3 from AC) stimulated one soleus muscle daily, leaving the other leg as an untrained within-subject control. Trained limb H-reflexes were assessed during year 1 (TR1) and year 2 (TR2) of training. Untrained limbs were tested during year 2 (UN). H-reflex amplitude was lower at 1, 2 and 5 Hz than at 0.1 or 0.2 Hz (p < 0.05). The pattern of depression differed between AC and UN (p < 0.05), but not between TR2 and UN (p > 0.05) despite significant adaptations in torque and fatigue resistance (p < 0.05). Three subjects who began training very early after SCI retained H-reflex post activation depression, suggesting that early intervention of daily muscular activity may be important.     

Structural and functional denervation of human detrusor after spinal cord injury

The bladder receives an extensive nerve supply that is predominantly cholinergic, but several putative transmitters are present, some of which are colocalized. Previous studies have shown increased levels of sensory nerves, reduced inhibitory transmitters, and structural and functional changes in the excitatory input in unstable bladder conditions. The present study compared the end-organ nerve supply to the bladder in spinal cord injury (SCI) with uninjured controls. Acetylcholinesterase histochemistry and double-label immunofluorescence were used to investigate neurotransmitter content, with confocal laser scanning microscopy to assess colocalization. Organ bath studies provided functional correlates for the structural changes in the excitatory innervation. Control samples had dense innervation of the detrusor containing a diverse range of transmitters. Hyperreflexic SCI samples showed patchy denervation, and areflexic SCI samples were diffusely denervated. Vasoactive intestinal polypeptide-, neuropeptide Y-, neuronal nitric oxide synthase-, and galanin-immunoreactive nerve fibers were reduced from frequent or moderately frequent to infrequent or very infrequent in SCI. Calcitonin gene-related peptide-immunoreactive fibers were infrequent in controls and SCI samples. Patterns of colocalization were unchanged, but significantly fewer fibers expressed more than one transmitter. The subepithelial plexus was markedly reduced and several of the smaller coarse nerve trunks showed no immunoreactivity to the transmitters assessed. There was no reduction in sensitivity to electrical field stimulation of intrinsic nerves in SCI, but the maximum force generated by each milligram of bladder tissue and the peak force as a proportion of the maximum carbachol contraction were significantly reduced and the responses were protracted. There was no significant functional atropine-resistant neuromuscular transmission in controls or SCI. The reported findings have clinical implications in the management of chronic SCI and development of new treatments.     

Musculoskeletal plasticity after acute spinal cord injury: effects of long-term neuromuscular electrical stimulation training

Maintaining the physiologic integrity of paralyzed limbs may be critical for those with spinal cord injury (SCI) to be viable candidates for a future cure. No long-term intervention has been tested to attempt to prevent the severe musculoskeletal deterioration that occurs after SCI. The purposes of this study were to determine whether a long-term neuromuscular electrical stimulation training program can preserve the physiological properties of the plantar flexor muscles (peak torque, fatigue index, torque-time integral, and contractile speed) as well as influence distal tibia trabecular bone mineral density (BMD). Subjects began unilateral plantar flexion electrical stimulation training within 6 wk after SCI while the untrained leg served as a control. Mean compliance for the 2-yr training program was 83%. Mean estimated compressive loads delivered to the tibia were approximately 1-1.5 times body weight. The training protocol yielded significant trained versus untrained limb differences for torque (+24%), torque-time integral (+27%), fatigue index (+50%), torque rise time (+45%), and between-twitch fusion (+15%). These between-limb differences were even greater when measured at the end of a repetitive stimulation protocol (125 contractions). Peripheral quantitative computed tomography revealed 31% higher distal tibia trabecular BMD in trained limbs than in untrained limbs. The intervention used in this study was sufficient to limit many of the deleterious muscular and skeletal adaptations that normally occur after SCI. Importantly, this method of load delivery was feasible and may serve as the basis for an intervention to preserve the musculoskeletal properties of individuals with SCI.     

骨髓间充质干细胞移植对脊髓损伤后轴突再生及Nogo-A蛋白表达的影响

正脊髓损伤(spinal cord injury,SCI)可导致患者损伤平面以下运动、感觉、反射及二便功能障碍,给家庭及社会造成严重的负担,目前尚无确切治疗方法。随着干细胞科学的飞速发展,干细胞移植有望成为治疗SCI的一种全新手段~([1])。但干细胞移植后对轴突生长的影响研究较少,而轴突再生对SCI后神经功能恢复起着至关重要的作用。现对骨髓间充质干细胞(bone marrow mesenchymal cells,BMSCs)移植治疗对轴突再生及Nogo-A蛋白表达的影响进行综述,探讨BMSCs移植治疗对促     

大鼠脊髓发育及损伤后NIDD mRNA表达的实验研究

目的：探讨在大鼠发育过程中及急性脊髓损伤后脊髓组织中NIDD （nNOS-interacting DHHC domain-containing protein with dendritic mRNA）mRNA的表达变化及意义。方法：采用改良Allen＇s打击法，咬除T8-10椎板后，造成大鼠脊髓损伤模型，致伤量为10×10g·cm；借助实时荧光定量PCR、原位杂交与免疫荧光结合的方法，定量、定位研究发育过程中及脊髓损伤后早期大鼠脊髓组织中NIDD mRNA与nNOS mRNA表达的时间和空间分布特征。结果：大鼠发育过程中，胚胎16d的大鼠脊髓中可见NIDD mRNA的高表达，在生后1d，与nNOS共表达于尚未分化成熟的前角，在白质也见NIDD的阳性信号。成年后呈低表达；nNOS mRNA于生后1～3d出现表达高峰；脊髓损伤后NIDD mRNA表达明显增多，在8h到达高峰，分布于脊髓前角、中间带、中央管周围及后角nNOS阳性的神经元，7d恢复至正常水平；nNOS mRNA在损伤后8h达到高峰，1d降低至正常水平。而且，在脊髓损伤后NIDD mRNA与nNOS mRNA二者表达呈正相关。结论：胎鼠脊髓中，NIDD高表达于nNOS阳性细胞，提示其在脊髓组织的发育成熟过程中的作用可能与nNOS相关。脊髓损伤后脊髓组织中NIDD与nNOS表达增多，提示在脊髓损伤的病理过程中，NIDD可能通过调节nNOS的细胞亚定位及活性而发挥一定的生物学作用。     

选择性线粒体分裂抑制剂抑制大鼠急性脊髓损伤后的细胞凋亡

目的 检测mdivi-1预处理对大鼠急性脊髓损伤(ASCI)后线粒体膜电位,凋亡诱导因子(AIF)释放及细胞凋亡的影响.方法 大鼠随机分为:假手术组(Sham组)、单纯脊髓损伤组(SCI组)、二甲基亚砜预处理组(DMSO组),mdivi-1预处理组(mdivi-1组).采用Allen's方法制备ASCI模型.JC-1标记法检测线粒体膜电位(MMP),Western blot方法检测线粒体及细胞核内AIF,TUNEL法检测细胞凋亡.结果 与Sham组相比,SCI组线粒体中AIF先降低后升高,最低点是8h(P＜0.01),而细胞核中AIF却呈相反趋势(P＜0.01),术后8 h MMP明显降低(P＜0.01),凋亡细胞数目明显增多(P＜0.01).与SCI 8 h组相比,mdivi-1组MMP明显升高(P＜0.01),线粒体中AIF明显增多(P＜0.01),细胞核中AIF明显降低(P＜0.01),凋亡细胞数目明显减少(P＜0.01).结论 Mdivi-1具有保护大鼠ASCI后MMP,抑制线粒体中AIF的释放和细胞凋亡的作用.     

Synaptic plasticity modulates the spontaneous recovery of locomotion after spinal cord hemisection

Several evidences have demonstrated that adult mammals could achieve a wide range of spontaneous sensory-motor recovery after spinal cord injury by means of various forms of neuroplasticity. In this study we evaluated the possibility that after low-thoracic spinal cord hemisection in the adult rat, significant hindlimb locomotor recovery could occur, and that this recovery may be driven, at least in part, by mechanisms of synaptic plasticity. In order to address these issues, we measured the expression levels of synapsin-I and brain-derived neurotrophic factor by Western blotting, at various time points after hemisection and correlated them with the motor performance on a grid walk test. Regression analysis showed that the expression of synapsin-I was strongly correlated with the spontaneous recovery of hindlimb locomotion (R=0.78). Conversely, neither the expression levels of synapsin-I nor the locomotor recovery were associated with the expression of brain-derived neurotrophic factor. Overall results indicate that after spinal cord hemisection, substantial recovery of hindlimb locomotion could occur spontaneously, and that synaptic plasticity within spinal circuitries below the level of the lesion, could be an important mechanism involved in these processes.     

Up-regulation of GAP-43 and growth of axons in rat spinal cord after compression injury

Summary The growth-associated protein-43 (GAP-43) is an axonal phosphoprotein which is expressed at high levels during development and is reinduced by regeneration in the PNS. Consequently it is believed to be a key molecule in the regulation of axonal growth. However, injury to the CNS does not result in significant regeneration and this has been suggested to correlate with a failure of central neurons to up-regulate GAP-43 after axotomy. We have examined a model of spinal cord injury which is unique in two respects; first dural integrity is maintained by compression of the cord with smooth forceps (thus excluding connective tissue elements) and, secondly, considerable axonal growth has been reported through the resulting lesion. Our previous studies have shown that GAP-43 is extensively distributed in the rat spinal cord (see accompanying paper), but here we have used anti-GAP-43 antiserum at a dilution which did not yield any immunostaining in normal cord. However, supranormal levels of GAP-43 were detected in cell bodies and axons around the lesion within four days of compression injury. Double immunostaining with the RT97 monoclonal antibody indicated that a small subpopulation of neurons local to the site of compression were axotomized and expressed GAP-43 and phosphorylated neurofilament epitopes in their cell bodies. Although damage to long axon tracts was extensive, there was no evidence of regeneration in white matter. On the other hand cavities which formed in grey matter provided an environment for axonal elongation. Immunolabelling with markers for astrocytes and endothelial cells was used to evaluate the interaction of elongating axons with endogenous CNS cell types. Sprouting axons, identified by the presence of elevated levels of GAP-43, did not appear to grow in contact with astrocytes but preliminary evidence suggested that newly formed capillaries provided an appropriate substrate.     

大剂量甲基强的松龙对大鼠急性损伤脊髓Nogo-A表达量影响的研究

目的：研究大剂量甲基强的松龙对急性脊髓损伤大鼠脊髓Nogo-A蛋白表达量的影响。方法：采用allen’s打击方法，将大鼠分为正常组、急性脊髓损伤组（对照组）和急性脊髓损伤＋大剂量MP组，损伤大鼠Tg-T10节段，分别于术后3、7、14d取受损节段大鼠脊髓，运用Western-blot方法测定各时相点Nogo-A表达量及其变化，并以HE染色和免疫组化染色对受损脊髓进行形态学观察。结果：Nogo-A蛋白在各组大鼠脊髓组织中均呈阳性表达，损伤后对照组与MP组各个时相点Nogo-A表达均显著高于正常组（P〈0.05），7d时最高，后逐渐下降，但14d的表达量仍高于正常组。其中大剂量MP组与对照组在各个时间点的表达量具有显著差异（P〈0．05），MP组在各个时间点的表达量显著低于对照组。结论：Nogo-A是SCI后脊髓神经纤维再生的主要抑制因子，大剂量MP对Nogo-A的表达具有明显的抑制作用。     

大鼠脊髓胶质瘢痕形成的规律*

背景：脊髓损伤后治疗不理想的原因是脊髓组织的囊变和胶质瘢痕的形成,因此,明确胶质瘢痕的发生发展规律具有重要意义。 目的：观察大鼠脊髓损伤后脊髓胶质瘢痕形成的空间分布、时间规律,以及轴突变化特征。 方法：采用改良Allen重物坠落法建立SD大鼠脊髓损伤模型,分别于损伤后1 d,3 d,5 d,1周,2周,4周,6周,8周,10周,12周取材。以正常饲养的大鼠作对照。 结果与结论：大鼠脊髓损伤后4周开始出现致密瘢痕增生,之后瘢痕厚度平稳下降,至损伤后10周形成光滑的囊腔壁,囊腔内无胶质纤维酸性蛋白阳性星形胶质细胞,损伤区囊腔周围的胶质瘢痕内可见密集肥大的星形胶质细胞,未见神经丝蛋白阳性轴突位于囊腔内。提示脊髓损伤后4周胶质瘢痕厚度达到高峰,囊腔与残存轴突之间开始形成机械屏障,损伤后10周瘢痕厚度趋于稳定。      

壳聚糖材料在脊髓损伤后神经再生的研究与作用

背景：组织工程支架材料壳聚糖能复合多种种子细胞和神经因子,维持受损组织正常的解剖结构,防止胶质瘢痕挤压,对脊髓损伤后神经再生具有重要的意义。 目的：介绍壳聚糖材料在修复脊髓损伤后神经再生领域的研究现状。 方法：由第一作者检索1990至2012年 PubMed数据库、CNKI数据库及万方数据库有关壳聚糖材料特性、壳聚糖导管移植治疗脊髓损伤的相关文献。 结果与结论：壳聚糖具有良好的物理、化学性能,并且具有良好的生物相容性、生物降解性,免疫抗原性小和无毒性等特殊生物医学特性,与嗅鞘细胞、骨髓间充质干细胞及神经干细胞具有良好的亲和性。壳聚糖材料制备的神经导管、支架能在脊髓损伤后桥接神经断端,维持神经再生的正常解剖结构,提供种子细胞及细胞因子载体,为损伤后神经再生提供良好的微环境,但目前对于壳聚糖导管的研究仍不够全面,仍有很多问题待解决。     

Some features of the stretch reflex after spinal cord injury

The object of the investigation was to study correlation between the state of the spinal reflex apparatus in spinal patients and the presence or absence of clonus. The magnitude of the electrical response of the soleus muscle to passive dorsiflexion of the angle at different speeds was studied. Clonus took place in 10 patients (group 1) and was absent in another 12 patients (group 2). Ten healthy subjects served as the control group. A considerable difference was found in the curves of distribution of magnitude of the responses for the different groups of subjects. Characteristically the patients of group 1 showed a shift of the model to the right, but the patients of group 2 showed a shift to the left compared with the mode to healthy subjects. The same pattern was found regardless of the angular velocity studied. The threshold velocity in the patients of group 2 was significantly higher than normal, whereas in the patients of group 1 it was close to normal. Activity in the calf muscles and ability to move about or even to walk were observed in most patients of group 1 but in only a few patients of group 2. It is suggested that the presence of clonus corresponds to a more normal state of the spinal reflex apparatus and to better clinical indices than in patients without clonus.Institute for Problems in Information Transmission, Academy of Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR, V. S. Rusinov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 87, No. 3, pp. 207–209, March, 1979.     

脊髓压迫性损伤大鼠海马和脊髓内BDNF的表达变化

目的探讨脑源性神经营养因子(BDNF)在脊髓压迫性损伤后的表达变化及作用。方法用自行设计的方法制作脊髓压迫模型,免疫荧光检测BDNF在星形胶质细胞、神经元和上下行轴突的表达;WB检测BDNF在大鼠海马及脊髓的表达。结果随着时间延长,受损部位的BDNF+-GFAP荧光强度逐渐增强;BDNF+-Tuj1荧光强度逐渐减弱;受损部位相邻上下段的BDNF+-NF200比受损部位的明显增强。海马和脊髓受损中心相邻的上、下段的BDNF蛋白表达在损伤后1d达到峰值,然后逐渐下降(P0.05);而脊髓受损中心的BDNF蛋白表达逐渐下降(P0.05)。结论脊髓损伤后,BDNF的表达下调,随伤后时间呈一定规律变化,是引起受损部位神经元表达下降的原因之一。     

Response characteristics of spinal cord dorsal horn neurons in chronic allodynic rats after spinal cord injury

The physiological mechanisms of chronic pain in patients with spinal cord injury (SCI) are poorly understood. In the present study, we explored response characteristics of dorsal horn neurons of spinally injured rats exhibiting chronic pain (pain-like response to innocuous mechanical and cold stimulation). Several abnormalities were found in the distribution and response characteristics of dorsal horn neurons in chronic allodynic rats. First, 17% of the recorded neurons (vs. 0% in control animals) had no receptive field. Most of these units were located at or close to the lesioned spinal segment, and they discharged spontaneously at high frequencies. Allodynic rats also showed a significant decrease in the proportion of low-threshold (LT) neurons and an increase in the proportion of wide dynamic range (WDR) neurons. The rate of spontaneous activity of high-threshold (HT) neurons was significantly higher in allodynic compared with control rats. Moreover, HT neurons in allodynic animals showed increased neuronal responses to mechanical stimulation. WDR neurons responded with higher discharge rates to innocuous von Frey hair stimulation in allodynic compared with control rats. The percentage of WDR and HT neurons showing afterdischarges to noxious pinch was also significantly increased in the allodynic rats. The proportion of WDR and HT neurons responding to innocuous cold stimulation respectively increased from 53 and 25% in control rats to 91 and 75% in allodynic animals. These results suggest that the chronic pain-like behaviors in spinally injured rats may be generated and maintained by abnormalities in dorsal horn neurons.     

Limited minocycline neuroprotection after balloon-compression spinal cord injury in the rat

Minocycline (MC), a second-generation tetracycline and anti-inflammatory agent reportedly provides neuroprotection following CNS injury. The objective of this study was to examine the neuroprotective effects of short and long-term MC treatment using balloon-compression spinal cord injury (SCI) in the rat. Rats subjected to SCI were treated with MC for 1 day (1DMC group; total dose 180 mg/kg) or 5 days (5DMC group; total dose 450 mg/kg) or placebo. The effects of MC treatment on locomotor recovery (BBB scale) and spinal cord white and gray matter sparing were evaluated for up to 28 days. Morphometric analysis showed that while MC treatment spared spinal cord white and gray matter rostral to the lesion epicenter in both, 1DMC and 5DMC groups, sparing of white and gray matter areas was not observed caudal to the traumatic lesion. In addition, MC treatment had no effect on final locomotor recovery. Limited improvement of spinal cord post-compression consequences raises questions about the neuroprotection efficiency of MC treatment following compression SCI in the rat.