一氧化氮在脊髓损伤中的作用

一氧化氮(NO)是兼有细胞间第二信使物质和细胞毒性作用的气体物质。近来发现其在脊髓创伤性损害中具有重要作用。文章从NO的神经生物学作用入手,结合有关最近研究资料,对脊髓损伤区NO浓度的变化,及对神经元的影响等予以综述。     

Necrostatin-1在小鼠脊髓损伤后继发性损伤中的作用

目的 探讨Necrostatin-1(Nec-1)在小鼠脊髓损伤后继发性损伤中的作用及机制。方法 将168只健康成年雌性LCR小鼠随机分为4组:对照组（48只）、脊髓损伤组（48只）、溶剂组（36只,鞘内注射4 μl二甲基亚砜）和治疗组[36只,鞘内注射4 μl Nec-1（4 mmol/L）]。采用血管夹钳夹小鼠脊髓建立脊髓损伤模型。伤后6、12、24、48 h采用免疫印迹法检测脊髓组织受体相互作用蛋白（RIP）1、3的表达;伤后24 h采用免疫共沉淀法评估RIP1和RIP3的相互作用;伤后24 h检测脊髓组织丙二醛（MDA）和活性氧簇（ROS）水平,电镜观察小鼠脊髓组织神经元线粒体损伤情况。结果 伤后48 h内,小鼠脊髓RIP1表达水平无明显变化;伤后6 h,小鼠脊髓RIP3表达水平明显增高,持续到伤后48 h。伤后24 h,治疗组和溶剂组RIP1和RIP3的表达水平均无明显差异;正常脊髓组织RIP1和RIP3相互作用较弱,脊髓损伤后RIP1和RIP3相互作用加强,而Nec-1显著抑制RIP1和RIP3相互作用。伤后24 h,脊髓神经元线粒体不同程度受损,而治疗组小鼠脊髓神经元线粒体结构保存相对较好。伤后24 h,脊髓组织MDA和ROS含量明显升高,而Nec-1能明显减少小鼠脊髓MDA和ROS含量。结论 小鼠脊髓损伤后,Nec-1通过抑制RIP1和RIP3的相互作用,进而抑制程序性坏死,减轻脊髓继发性损伤。Nec-1能降低ROS产物,减轻氧化应激损伤,保护线粒体功能。     

TNF在脊髓损伤中的研究进展

肿瘤坏死因子(TNF)作为一种前炎性介质,在炎症和免疫反应中起重要作用。脊髓损伤(SCI)后TNF活性增加,参与炎症和损伤级联反应,加剧伤区缺血缺氧,进而激活小胶质细胞、星型胶质细胞和巨噬细胞,诱发轴突损伤和变性;同时,TNF及其家族成员FasL作为死亡配体可分别与其受体TNFR和Fas结合,触发凋亡信号转导,激活caspase,导致神经细胞凋亡,从而加剧继发性脊髓损害。SCI后抑制TNF活性,调控炎症反应,可减轻继发性脊髓损害,有助于损伤脊髓功能的恢复。     

铁死亡在脊髓损伤中的作用及研究进展

<正>脊髓损伤(spinal cord injury,SCI)是一种严重致残和致命的临床疾病,并伴随着沉重的经济负担。在过去的30年中,全球SCI的发病率持续增长。据报道,全球创伤性SCI的总体发病率为每10万人10.5例,即全球每年约有768,473例创伤性SCI发生,其中48.8%需要手术干预^[1]。     

星形胶质细胞在脊髓损伤中的研究进展

<正>近年来,脊髓损伤(spinal cord injury,SCI)的发病率在我国乃至世界呈明显上升趋势。脊髓损伤后的神经再生问题,一直是科研人员和临床工作者研究的一个重点和难点。脊髓损伤后,阻碍轴突再生的主要的因素是小胶质细胞激活、星形胶质细胞(astrocyte,AS)增殖活化和胶质瘢痕的形成[1]。而AS的增殖活化后并分泌多种细胞外基质共同形成神经胶质瘢痕是抑制脊髓损伤修复的最主要障碍。最近研究显示,星     

脊髓继发性损伤的实验与临床研究

脊髓伤分原发伤与继发伤。一部分脊髓伤,解剖上未横断,伤后当时无截瘫,但由于继发血液循环障碍,出现脊髓缺血、出血及中心性坏死,使脊髓内重要结构产生继发性的不可逆性损害,导致完全截瘫的不良后果。本文报道犬、小白鼠的实验性脊髓伤早期病理改变,并以23例继发性脊髓伤的分析,探讨脊髓继发性损伤的发生机理。实验提示早期应用钙通道阻断剂尼维地平,有利于改善脊髓缺血引起的继发性脊髓损害。     

脊髓继发性损伤的实验与临床研究

脊髓伤分原发伤与继发伤，一部分脊髓伤，解剖上未横断，伤后当时无截瘫，但由于继发血液循环障碍，出现脊髓缺血、出血、中心性坏死。使脊髓内重要结构产生继发性的不可逆性损害，导致完全截瘫的不良后果。本文报道犬、大白鼠的实验性脊髓伤早期病理改变，并从２３例继发性脊髓伤的分析，探讨脊髓继发性损伤的发生机理。实验提示早期应用钙通道阻断剂尼维地平，有利于改善脊髓缺血引起的继发性脊髓损害。     

白细胞介素-10在脊髓损伤中的研究进展

一、白细胞介素-10(IL-10)概述 IL-10是一种免疫调节因子,人类内源IL-10产生的主要细胞是巨噬细胞和单核细胞.     

脊髓损伤机制研究进展

脊髓损伤（SCI）是导致残疾的重要原因，每年100万人群中有20～40例的发生率，给病人和家庭带来沉重的经济，社会和精神负担。SCI后引起的功能下降主要由原发性和继发性损伤共同造成。 1原发性损伤 原发损伤部位的机械力量直接剪切神经细胞和内皮细胞的胞膜，由于灰质区柔软并富于血管，首先在这些区域形成出血坏死灶。     

脊髓损伤机制研究进展

脊髓损伤(SCI)是导致残疾的重要原因,每年100万人群中有20～40例的发生率,给病人和家庭带来沉重的经济,社会和精神负担.SCI后引起的功能下降主要由原发性和继发性损伤共同造成.     

脊髓缺血再灌注损伤时血清及脊髓组织一氧化氮水平的动态变化及意义

目的 观察一氧化氮(NO)在脊髓缺血再灌注损伤(SCIRI)时血清及脊髓组织中的变化,探讨其在SCIRI中的意义. 方法 采用Zivin法建立家兔SCIRI模型,动态观察NO在血清和脊髓组织中的表达. 结果 血清NO在缺血再灌注(IRI)组缺血末期明显上升,IRI后2 h达到峰值,与缺血前比较差异有统计学意义(P<0.05),IRI后6 h、12 h明显降低,与缺血前及Sham组比较差异有统计学意义(P<0.05);脊髓组织中NO在缺血末期明显升高并达到峰值,缺血再灌注后2h、6 h逐渐下降,与Sham组比较差异有统计学意义(P<0.05),缺血再灌注后12 h下降到Sham组水平. 结论 NO在SCIRI后血清和脊髓组织中表达增高,可能在SCIRI病理过程神经元损伤与修复中发挥一定作用.     

Expression of nitric oxide synthase in the spinal cord after selective brachial plexus injury

BACKGROUND: Some researches showed that motoneurons in spinal cord anterior horn wound die following brachial plexus injury, but the concrete mechanism of motoneurons death remains unclear. OBJECTIVE: To observe the expression of nitric oxide synthase (NOS) and survival of C7 motoneurons in spinal cord of rats after selective brachial plexus injury. DESIGN: A randomized controlled animal experiment. SETTING:Department of Anatomy, Sun Yet-sen Medical College, Sun Yet-sen University. MATERIALS: Totally 35 adult healthy male Sprague-Dawley rats with the body mass of 200-300 g were provided by Experimental Animal Center, Sun Yet-sen Medical College, Sun Yat-sen University. The rats were divided into control group (n =5) and experimental group(n =30) by random number table method, and the experimental group was divided into three injury subgroups: anterior root avulsion group, dorsal root transection group and spinal cord hemisection group, 10 rats in each group. There were horse anti-neuronal NOS (nNOS) polycolonal antibody (Sigma company) and nicotina mideadeninedinucleotide phosphate (NADPH-d) (Sigma Company). METHODS: The experiment was performed at Department of Anatomy, Sun Yet-sen Medical College, Sun Yet-sen University between September 2004 and April 2005. ①After anesthetizing the rats, the spinous process of second thoracic vertebra as a marker, the vertebra was exposed from C5 to T1 and the lamina of vertebra was unclenched, and spinal dura mater was carved to expose the spinal nerve dorsal roots of C5-T1. The right ventral root of C7 was avulsed, and the residual root was removed in anterior root avulsion group. The right ventral root of C7 was avulsed and the right dorsal roots of brachial plexus (C5-T1) were cut off in dorsal root transection group. In spinal cord hemisection group, the hemisection between the C5 and C6 spinal segment on right side and avulsion of right ventral root of C7 were made. In the control group, the vertebra from C5 to T1 was unclenched and the skin of wound was sutured. ②Three weeks after operation, behavior of rats was observed. The rats were killed after anesthesia. The C7 segment of spinal cord was removed and treated with NADPH-d staining, neutral red counterstaining and NOS immunohistochemistry staining to detect the expression of NOS. MAIN OUTCOME MEASURES: The expression of NOS and survival of C7 motoneurons in spinal cord of rats 3 weeks after operation. RESULTS: Among the 35 included rats, 3 rats died 2 weeks following operation, so totally 32 rats were involved in the result analysis. ①NADPH-d positive neurons of in anterior horn of C7 in the three groups: The NADPH-d positive neurons could be found in anterior horn of C7 in the three groups. The percentage of that in anterior root avulsion group to that of non-injury side of spinal cord was(20.98±2.65)%, (29.43±6.81)% in dorsal root transection group and (31.74±6.80)% in spinal cord hemisection group. There was significant difference among the three injury groups(F =5.135，P =0.016). There was significant difference in anterior root avulsion group with dorsal root transection group and spinal cord hemisection group (t =2.562，3.167，P < 0.05). There was no significant difference between the dorsal root transection group and spinal cord hemisection group (P =0.534). ②survival rate of motoneurons in anterior horn of C7: There were dead motoneurons in the three injury groups, the percentages of surviving motoneurons to that of non-injured side of spinal cord were (69.22±4.04)%，(62.01±3.82)% and (56.74±6.86)%, respectively. There were significant differences among the three groups (F =9.508，P =0.002). The anterior root avulsion group was significantly different from the other two groups(t =2.764，4.587，P < 0.05). There was no significant difference between the dorsal root transection group and spinal cord hemisection group(P =0.073). CONCLUSION: The selective brachial plexus injury can induce the up-regulation of NOS expression in motorneurons of spinal cord anterior horn and block descending pathway of cortex to cause the more significant up-regulation of NOS and low survival rate in motoneurons. It indicates that descending pathway of cortex can inhibit the NOS expression in motorneurons of spinal cord anterior horn, and the high NOS expression might induce the death of motorneurons in spinal cord anterior horn.     

Ruxolitinib attenuates secondary injury after traumatic spinal cord injury

Excessive inflammation post-traumatic spinal cord injury(SCI)induces microglial activation,which leads to prolonged neurological dysfunction.However,the mechanism underlying microglial activation-induced neuroinflammation remains poorly understood.Ruxolitinib(RUX),a selective inhibitor of JAK1/2,was recently reported to inhibit inflammatory storms caused by SARS-CoV-2 in the lung.However,its role in disrupting inflammation post-SCI has not been confirmed.In this study,microglia were treated with RUX for 24 hours and then activated with interferon-γfor 6 hours.The results showed that interferon-γ-induced phosphorylation of JAK and STAT in microglia was inhibited,and the mRNA expression levels of pro-inflammatory cytokines tumor necrosis factor-α,interleukin-1β,interleukin-6,and cell proliferation marker Ki67 were reduced.In further in vivo experiments,a mouse model of spinal cord injury was treated intragastrically with RUX for 3 successive days,and the findings suggest that RUX can inhibit microglial proliferation by inhibiting the interferon-γ/JAK/STAT pathway.Moreover,microglia treated with RUX centripetally migrated toward injured foci,remaining limited and compacted within the glial scar,which resulted in axon preservation and less demyelination.Moreover,the protein expression levels of tumor necrosis factor-α,interleukin-1β,and interleukin-6 were reduced.The neuromotor function of SCI mice also recovered.These findings suggest that RUX can inhibit neuroinflammation through inhibiting the interferon-γ/JAK/STAT pathway,thereby reducing secondary injury after SCI and producing neuroprotective effects.     

一氧化氮合酶抑制剂对脊髓损伤后运动功能的影响

目的观察诱导型和神经型一氧化氮合酶(iNOS,nNOS)抑制剂对大鼠脊髓损伤(SCI)后运动功能的影响和机理。方法大鼠脊髓压迫伤后分别给予iNOS和nNOS抑制剂—氨基胍(AG)和7-硝基吲唑(7-NI)进行治疗,24h后用分光光度法测定组织中一氧化氮(NO)含量和一氧化氮合酶(NOS)活性,72h后用流式细胞仪检测神经细胞凋亡情况,4周后用电生理和动物行为学等指标评价运动功能的恢复情况。结果AG和7-NI均可以抑制组织中的NO含量,并使NOS活性下降,同时降低神经细胞的凋亡比率,对运动功能的恢复前者优于后者。结论脊髓损伤后应用NOS抑制剂可以使伤后运动功能得到改善,AG的作用似乎更明显,提示iNOS活性变化可能对脊髓损伤的恢复更具决定作用。     

Minocycline targets multiple secondary injury mechanisms in traumatic spinal cord injury

Minocycline hydrochloride (MH), a semi-synthetic tetracycline derivative, is a clinically available antibi-otic and anti-inflammatory drug that also exhibits potent neuroprotective activities. It has been shown to target multiple secondary injury mechanisms in spinal cord injury, via its anti-inflammatory, anti-oxidant, and anti-apoptotic properties.The secondary injury mechanisms that MH can potentially target include inflammation, free radicals and oxidative stress, glutamate excitotoxicity, calcium influx, mitochondrial dysfunction, ischemia, hemorrhage, and edema. This review discusses the potential mechanisms of the multifaceted actions of MH. Its anti-inflammatory and neuroprotective effects are partially achieved through conserved mechanisms such as modulation of p38 mitogen-activated protein kinase (MAPK) and phos-phoinositide 3-kinase (PI3K)/Akt signaling pathways as well as inhibition of matrix metalloproteinases (MMPs). Additionally, MH can directly inhibit calcium influx through the N-methyl-D-aspartate (NMDA) receptors, mitochondrial calcium uptake, poly(ADP-ribose) polymerase-1 (PARP-1) enzymatic activity, and iron toxicity. It can also directly scavenge free radicals. Because it can target many secondary injury mechanisms, MH treatment holds great promise for reducing tissue damage and promoting functional re-covery following spinal cord injury.     

Immunization with A91 peptide or copolymer-1 reduces the production of nitric oxide and inducible nitric oxide synthase gene expression after spinal cord injury

Immunization with neurally derived peptides (INDP) boosts the action of an autoreactive immune response that has been shown to induce neuroprotection in several neurodegenerative diseases, especially after spinal cord (SC) injury. This strategy provides an environment that promotes neuronal survival and tissue preservation. The mechanisms by which this autoreactive response exerts its protective effects is not totally understood at the moment. A recent study showed that INDP reduces lipid peroxidation. Lipid peroxidation is a neurodegenerative phenomenon caused by the increased production of reactive nitrogen species such as nitric oxide (NO). It is possible that INDP could be interfering with NO production. To test this hypothesis, we examined the effect of INDP on the amount of NO produced by glial cells when cocultured with autoreactive T cells. We also evaluated the amount of NO and the expression of the inducible form of nitric oxide synthase (iNOS) at the injury site of SC-injured animals. The neural-derived peptides A91 and Cop-1 were used to immunize mice and rats with SC injury. In vitro studies showed that INDP significantly reduces the production of NO by glial cells. This observation was substantiated by in vivo experiments demonstrating that INDP decreases the amount of NO and iNOS gene expression at the site of injury. The present study provides substantial evidence on the inhibitory effect of INDP on NO production, helpingour understanding of the mechanisms through which protective autoimmunity promotes neuroprotection.     

Neuroprotective and neurodestructive functions of nitric oxide after spinal cord hemisection

Nitric oxide (NO) may subserve different functions in different central neurons subjected to axotomy. The difference may depend on whether the neurons basally express neuronal nitric oxide synthase (nNOS), a biosynthetic enzyme of NO. This is supported by our previous finding that suggests the differential role of NO in neurons of nucleus dorsalis (ND) and red nucleus (RN) which have different basal expression of nNOS. This study aimed to establish firmly the functions of NO, as revealed by nNOS immunoreactivity and nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) histochemistry, by the administration of endogenous NO donor, l-arginine (l-arg), and NOS inhibitor, l-N(G)-nitroarginine methyl ester (l-NAME). To relate the role of NO to glutamate receptors (GluR), the distributions of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) and N-methyl-d-aspartate receptor (NMDAR) in the two nuclei were revealed by immunohistochemical techniques. nNOS immunoreactivity was void in ND neurons, but expressed weakly in the RN normally. It was induced in ipsilateral ND neurons and upregulated on both sides of RN after spinal cord hemisection. Neuronal loss in the ipsilateral ND was augmented by l-arg, but reduced by l-NAME. In the contralateral RN, l-arg attenuated neuronal loss. NMDAR1 was present in most neurons in ND. After axotomy, some NMDAR1 immunoreactive neurons of the ipsilateral ND were induced to express NOS, whereas RN neurons showed strong staining for NMDAR1 and all the AMPA subunits. Most of the NOS-positive neurons in the RN were coexistent with GluR2 in normal rats and those subjected to axotomy. The present data demonstrated that NO exerted neurodestructive function in the non-NOS-containing ND neurons characterized by NMDAR as the predominant glutamate receptor. NO might be beneficial to the NOS-containing RN neurons. This could be attributed to the presence of GluR2. Possible diverse synthesizing pathways of NO in two different central nuclei were suggested from the observation that NOS was colocalized with NADPH-d in ND neurons, but not in RN neurons.     

Neuronal nitric oxide synthase immunoreactivity in the spinal cord in amyotrophic lateral sclerosis

We investigated the spinal cords of 15 patients with sporadic amyotrophic lateral sclerosis (ALS) immunohistochemically using an anti-human neuronal nitric oxide synthase (nNOS) antibody to examine whether there is increased nNOS immunoreactivity in anterior horn neurons. Specimens from 16 patients without any neurological disease served as controls. In the controls, nNOS immunoreactivity of large anterior horn neurons was detected in 10 out of 16 cases. However, there were few nNOS-positive neurons, and most of large anterior horn neurons were spared. In the ALS patients, the mean number of nNOS-positive anterior horn neurons per transverse section of L4 and L5 was significantly larger (16.2 +/- 10.9) than that in the controls (7.0 +/- 9.2) (P < 0.0001). Moreover, 41.4% of large anterior horn neurons in ALS showed nNOS immunoreactivity in remarkable contrast to 7.6% in the controls. All ALS patients, whether showing mild, moderate or severe depletion of anterior horn neurons, displayed a higher percentage of nNOS-positive anterior horn neurons than the control patients showing nNOS immunoreactivity (P < 0.01). Most of the remaining anterior horn neurons in ALS showed more intense nNOS immunoreactivity on the surface of the neurons and their neuronal processes compared with the controls. Degenerated anterior horn neurons frequently demonstrated more intense nNOS immunoreactivity on the surface of the neurons than normal-appearing neurons. Some anterior horn cells displayed nNOS immunoreactivity in the somata. Dot-like nNOS deposits on anterior horn neurons were also positively immunoreactive with anti-synaptophysin antibody. Thus, increased nNOS expression is located mainly at the synaptic sites on the anterior horn neurons in sporadic ALS, which may be related to the degeneration of anterior horn neurons in this disease. Further studies are needed to determine whether the increased nNOS immunoreactivity plays a neuroprotective or neurotoxic role in the anterior horn neurons, and to show nitric oxide production in ALS.     

Function of microglia and macrophages in secondary damage after spinal cord injury

Spinal cord injury （SCI） is a devastating type of neurological trauma with limited therapeutic op- portunities. The pathophysiology of SCI involves primary and secondary mechanisms of injury. Among all the secondary injury mechanisms, the inflammatory response is the major contrib- utor and results in expansion of the lesion and further loss of neurologic function. Meanwhile, the inflammation directly and indirectly dominates the outcomes of SCI, including not only pain and motor dysfunction, but also preventingneuronal regeneration. Microglia and macrophages play very important roles in secondary injury. Microglia reside in spinal parenchyma and survey the microenvironment through the signals of injury or infection. Macrophages are derived from monocytes recruited to injured sites from the peripheral circulation. Activated resident microglia and monocyte-derived macrophages induce and magnify immune and inflammatory responses not only by means of their secretory moleculesand phagocytosis, but also through their influence on astrocytes, oligodendrocytes and demyelination. In this review, we focus on the roles of mi- croglia and macrophages in secondary injury and how they contribute to the sequelae of SCI.     

Spatiotemporal expression of inducible nitric oxide synthase and cyclooxygenase 2 in the spinal cord during early stage sciatic nerve crush injury

BACKGROUND: Previous studies have shown that inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) participate in inflammatory immune responses and neuropathic pain following peripheral nerve injury. However, few reports have addressed time-dependent expression of iNOS and COX-2 following peripheral nerve injury. OBJECTIVE: To investigate spatiotemporal expression of iNOS and COX-2 during early stage sciatic nerve crush injury.DESIGN, TIME AND SETTING: The randomized, controlled, animal experiment was performed at the Laboratory of Applied Anatomy, Department of Human Anatomy and Neurobiology, Central South University, China from September 2006 to September 2007.MATERIALS: Mouse anti-rat iNOS monoclonal antibody and goat anti-rat COX-2 monoclonal antibody (Transduction Laboratory, USA), as well as biotinylated rabbit anti-mouse lgG and biotinylated rabbit anti-goat IgG (Santa Cruz Biotechnology, USA) were used in the present study.METHODS: A total of 48 healthy, adult, Sprague Dawley rats were randomly assigned to three groups. In the model group (n = 32), crush injury to the right sciatic nerve was established using an artery clamp. The model group was further assigned to four subgroups according to survival time (6,12, 24, and 72 hours), respectively (n = 8). Sham surgery (n = 8) and normal control (n = 8) groups were also established.MAIN OUTCOME MEASURES: iNOS and COX-2 expression was detected in the L4-6 spinal cord with immunohistochemistry. Gray values of iNOS- and COX-2-postive cells in the anterior horn and posterior horn of spinal cord, as well as quantification of iNOS- and COX-2-positive cells in the anterior horn of spinal cord, were measured.RESULTS: iNOS and COX-2 expression gradually increased in the anterior horn and posterior horn of the spinal cord on the damaged side over time from 6 hours following sciatic nerve injury (P＜0.05) and peaked at 72 hours. Simultaneously, the number of iNOS- and COX-2-positive cells similarly increased in the anterior horn of spinal cord on the damaged side (P＜ 0.05).CONCLUSION: iNOS and COX-2 expression increased in the spinal cord during early stage sciatic nerve crush, which suggested that iNOS and COX-2 participate in occurrence and development of inflammatory immune responses following peripheral nerve injury.