脊髓损伤后一氧化氮含量及一氧化氮合酶活性的变化与脊髓水肿的关系

目的 :为了探讨脊髓损伤后一氧化氮 (NO)含量及其合酶 (NOS)活性与脊髓水肿的关系。方法 :测定不同程度脊髓损伤后NO含量及NOS活性的变化 ,同时测定脊髓组织含水量。结果 :随着损伤程度的增加 ,NO含量及NOS活性均增加 ,脊髓组织水肿增加。结论 :脊髓损伤后NO含量及NOS活性增加 ,与脊髓组织的水肿密切相关 ,提示NO参与了脊髓伤后的病理生理改变。     

急性脊髓损伤后诱生型一氧化氮合酶的表达、分布及作用

目的：研究大鼠急性脊髓损伤（spinal cord injury,SCI)后不同时间脊髓内诱生型一氧化氮合酶（inducble nitric oxide synthase,iNOS)的表达及其在不同类型细胞中的分布、血清中一氧化氮（nitric oxide,NO)含量的变化及iNOS特异性抑制剂氨基胍（aminoguanidine,AG)对大鼠后肢功能的影响。方法：Allen′s模型致伤后，分别于损伤后1、2、3、5、7d取伤段脊髓，作蛋白质印迹分析。在SCI后3d，用免疫荧光和免疫组化顺序标记方法分析iNOS在脊髓神经元、小胶质细胞和星形细胞中的表达与分布。应用比色法测定SCI后血清硝酸盐和亚硝酸盐的含量。观察腹腔注射20mg/kg、200mg/kg AG后SCI大鼠后肢功能的变化。结果：SCI后1d可见iNOS表达，3d达高峰，7d明显降低。在SCI后，神经元、星形细胞和小胶质细胞中均可iNOS表达，其中以神经元表达为主。SCI后血清硝酸盐和亚硝酸盐的含量于伤后1h和3-7d时出现两个高峰。损伤后腹腔注射20mg/kg、200mg/kg AG均能显著抑制血清硝酸盐和亚硝酸盐含量的升高，同时大鼠后肢功能显著恢复。结论：SCI后脊髓内iNOS表达增高，并分布在以神经元为主的多种细胞中。iNOS产生的NO加重了继发性脊髓损伤，对iNOS的抑制可能有助于脊髓损伤后神经功能的恢复。     

丙戊酸对大鼠急性脊髓损伤后氧化应激的影响

[目的]探讨丙戊酸(VPA)对大鼠脊髓损伤(SCI)后氧化应激的影响。[方法]72只雄性SD大鼠随机分为3组:假手术组(C组)、损伤组(SCI组)和丙戊酸保护组(VPA组)。采用改良的Allen法制作脊髓损伤动物模型。VPA组术后即刻及其后每12 h皮下注射VPA 300 mg/kg至取材;C组和SCI组在相应时间点注射等体积的生理盐水。大鼠在伤后24、48、72 h和1周先行后肢运动功能BBB评分,随后处死取材。通过石蜡切片HE染色观察脊髓组织病理变化,并用免疫组化法检测诱导型一氧化氮合酶(iNOS)的表达;通过化学比色法测定脊髓组织中丙二醛(MDA)和谷胱甘肽过氧化物酶(GSH-Px)的含量。[结果]BBB评分显示C组运动功能未受影响,VPA组的BBB评分均高于SCI组,两者相比在伤后48、72 h和1周差异有显著性(P<0.01)。HE染色示C组脊髓组织形态正常,VPA组各时间点的病理变化与SCI组相比没有明显改善。C组偶见或未见iNOS阳性表达细胞。与C组相比,SCI组和VPA组的iNOS表达均明显增加(P<0.05),在伤后72 h达高峰,但VPA组的iNOS表达在各时间点均明显低于SCI组(P<0.05)。SCI组和VPA组脊髓组织的MDA含量明显高于C组,而GSH-Px活性明显低于C组(P<0.05),VPA组和SCI组相比较,MDA含量在各时间点均明显下降,GSH-Px活性均明显升高(P<0.05)。[结论]VPA通过减轻SCI所诱导的氧化应激,从而对SCI发挥保护作用。     

烧伤大鼠小肠组织中两型一氧化氮合酶变化的观察

目的 研究烧伤后大鼠小肠组织中两型一氧化氮合酶的变化及与一氧化氮(NO)的关系。方法 采用30％TB-SAⅢ度烧伤大鼠模型,分别检测了小肠组织中NO含量及原生型NOS(cNOS)和诱导型NOS(iNOS)的活性,并分析了NO的变化规律及其与两型NOS之间的关系。结果 烧伤后小肠组中iNOS活性大幅上升,与NO的变化趋势一致,二者呈显著正相关(P<0.01),而cNOS活性呈下降趋势,与NO相关不显著(P<0.05)。结论 烧伤后小肠组织中NO的变化主要受iN-OS活性影响,iNOS活性上升,cNOS活性下降可能与烧伤后胃肠道病理变化密切相关。     

大鼠脊髓损伤后诱导型一氧化氮合酶基因表达变化的实验研究

目的探讨大鼠脊髓损伤后诱导型一氧化氮合酶(iNOS)mRNA表达的变化规律.方法SD大鼠48只,随机分为8组,采用Allen's脊髓损伤打击模型,以逆转录-聚合酶链反应(RT-PCR)法测定伤段脊髓组织iNOS mRNA表达情况.结果iNOS mRNA在脊髓损伤前即有表达,损伤后早期无明显变化,伤后72h开始升高,1周时达到高峰.结论脊髓继发性损害的持续时间可能大于传统观念,针对继发性损害所作的治疗应持续至脊髓损伤后较长的一段时间.     

大鼠脊髓损伤后一氧化氮合酶基因表达的变化

目的　探讨大鼠脊髓损伤后3种类型一氧化氮合酶（NOS）mRNA表达的变化规律。方法　成年SD大鼠36只,随机分为种类6组,每组6只大鼠。建立大鼠脊髓压迫伤模型,以逆转录-聚合酶链反应（RT-PCR）法测定伤段脊髓组织神经型（nNOS）、诱导型（iNOS）及内皮型（eNOS）一氧化氮合酶的mRNA表达情况。结果　脊髓压迫伤后nNOSmRNA及NOSRNA表达增强,伤后6h达到高峰0.633±0.012、1.236±0.207;iNOSmRNA表达亦增高,但在伤后24h才达到高峰1.043±0.049。结论　脊髓损伤后NOSmRNA的表达增强,但不同类型的NOSmRNA变化规律不同,增强或抑制不同NOSmRNA的表达可能减轻脊髓继发性损伤。     

一氧化氮(NO)在脊髓缺血再灌注损伤中作用的实验研究

目的　研究一氧化氮 (NO)在脊髓缺血再灌注损伤中的作用。方法　夹闭大鼠腹主动脉制成缺血再灌注模型 ,随机分成L -NAME组和再灌注组 ,L -NAME组每日腹腔注射一氧化氮合酶(NOS)非特异性抑制剂L -硝基精氨酸甲酯 (L -NAME) 10mg/kg体重 ,两周时取大鼠脊髓做NOS免疫组织化学染色、组织学及超微病理观察。结果　脊髓缺血再灌注后前角运动神经元出现固有型一氧化氮合酶 (cNOS)阳性表达 ,同时伴随前角运动神经元损伤 ;应用L -NAME后可减少cNOS的异常表达 ,减轻前角运动神经元损伤。结论　局部组织中NO产生增多可能是脊髓再灌注损伤的机制之一。     

神经病理性疼痛大鼠脊髓背角一氧化氮合酶各亚型的表达及活性变化

目的 比较神经病理性疼痛大鼠模型脊髓背角中神经型(nNOS),诱导型(iNOS)和内皮型(eNOS)三种一氧化氮合酶(NOS)的表达及活性变化.方法 雌性SD大鼠20只,150～200 g,随机均分为坐骨神经保留性损伤(SNI)组和对照组.SNI组大鼠于左后肢制备SNI模型,对照组大鼠暴露坐骨神经后立即缝合手术切口.术后观测疼痛的变化,于术后第14天断头处死大鼠,截取L4～6段脊髓,分离左右侧脊髓,于-80℃储存.SNI组和对照组各取5只大鼠脊髓,RT-PCR技术扩增nNOS、eNOS和iNOS片段,以β-actin作为内参照,比较SNI组与对照组NOS表达的相对差异.取两组另外5只大鼠脊髓冰上迅速匀浆,均取40 μg的蛋白,分别检测组成型NOS(cNOS,即nNOS和eNOS)和iNOS的活性.结果 SNI组手术侧nNOS、iNOS的mRNA表达均高于SNI组非手术侧和对照组手术侧(P<0.05),而eNOS的表达在SNI组手术侧、非手术侧和对照组手术侧之间差异并无统计学意义.NOS亚型催化活性检测显示SNI组手术侧iNOS和cNOS的活性均高于SNI组非手术侧和对照组手术侧(P<0.05).结论 神经病理性疼痛大鼠模型脊髓背角中iNOS的表达及其合成NO的活性均增加,可能促进了疼痛的发生,nNOS在疼痛中可能具有较强的调节能力.     

氨基胍对脊髓损伤后诱导性一氧化氮合酶表达的影响

目的　探讨氨基胍 (AG)对脊髓损伤后诱导性一氧化氮合酶 (iNOS)表达变化的影响及机制。方法　用Nystrom法 (锤重 3 5 g ,10min)制成大鼠脊髓损伤的动物模型 ,采用免疫组织化学技术和同位素标记方法检测脊髓组织iNOS蛋白及iNOS活性在脊髓损伤及应用AG后的变化。结果　脊髓未损伤时无iNOS表达 ;损伤后出现表达上调且表达量与伤后时间呈正相关 ,损伤后 2 4hiNOS蛋白及活性分别为 2 2 .60± 2 .3 6、0 .97± 0 .0 7;应用AG后两者出现抑制性改变为 17.40±2 .0 7、0 .5 2± 0 .0 3 (P <0 .0 1)。结论　iNOS是脊髓继发性损伤中可明显影响神经功能的重要因子 ,通过应用AG可明显抑制脊髓损伤后iNOS的高表达并降低其对神经组织的破坏作用。     

脊髓损损后一氧化氮合酶活性变化的动态观察及其基因表达

目的：观察一氧化氮合酶在脊髓损伤中的变化及其机制。方法：用液压致伤装置造成大鼠脊髓中、重度损伤，伤后不同时间分别测量损伤区NOS活性。结果：显示脊髓损伤后早期NOS活性一过性升高，而后又迅速降低，其升高、降低幅度与损伤严重程度相一致，提示一氧化氮参与继发性脊损伤病理过程NOSmRNA原位杂交法，发现脊髓中度损伤后30minNOSmRNA的表达水平没有明显变化。结论：提示脊髓损伤早期NOS活性增高主要由于刺激因素如钙离子等使没有发挥活性的NOS激活，使酶蛋白总量增加引起的。     

Acute molecular perturbation of inducible nitric oxide synthase with an antisense approach enhances neuronal preservation and functional recovery after contusive spinal cord injury

Abstract Inducible nitric oxide synthase (iNOS) is a key mediator of inflammation and oxidative stress produced during pathological conditions, including neurodegenerative diseases and central nervous system (CNS) injury. iNOS is responsible for the formation of high levels of nitric oxide (NO). The production of highly reactive and cytotoxic NO species, such as peroxynitrite, plays an important role in secondary tissue damage. We have previously demonstrated that acute administration of iNOS antisense oligonucleotides (ASOs) 3?h after moderate contusive spinal cord injury (SCI) potently inhibits iNOS-mediated increases in NO levels, leading to reduced blood-spinal cord barrier permeability, decreased neutrophil accumulation, and less neuronal cell death. In the current study we investigated if iNOS ASOs could also provide long-term (10-week) histological and behavioral improvements after moderate thoracic T8 contusive SCI. Adult rats were randomly assigned to three groups (n=10/group): SCI alone, SCI and mixed base control oligonucleotides (MBOs), or SCI and iNOS ASOs (200?nM). Oligonucleotides were administered by spinal superfusion 3?h after injury. Behavioral analysis (Basso-Beattie-Bresnahan [BBB] score and subscore) was employed weekly for 10 weeks post-SCI. Although animals treated with iNOS ASOs demonstrated no significant differences in BBB scores compared to controls, subscore analysis revealed a significant improvement in foot positioning, trunk stability, and tail clearance. Histologically, while no gross improvement in preserved white and gray matter was observed, greater numbers of surviving neurons were present adjacent to the lesion site in iNOS ASO-treated animals than controls. These results support the effectiveness of targeting iNOS acutely as a therapeutic approach after SCI.     

Changes in nitric oxide synthase expression in young and adult rats after spinal cord injury

OBJECTIVE: To examine the clinical meaning of the changes in nitric oxide synthase (NOS) expression and activity after spinal cord injury (SCI) according to the age of the experiment animal. MATERIAL AND METHOD: Ten 5- and 16-week-old Sprague-Dawley rats were laminectomized at T10 and SCI induced at this level using a New York impactor. Outcome measures to assess SCI utilized the Basso-Beatti-Bresnahan scale to quantitate hind limb motor dysfunction as a functional outcome measure. NOS isoforms (nNOS, neuronal NOS; iNOS, inducible NOS; and eNOS, endothelial NOS) were also immunolocalized in sections of control and spinal cord injury in the two sample groups using specific monoclonal antibodies. Student's t-test evaluated the difference between the young and adult rats, and P<0.05 was considered as significant value. RESULT: As the expression of nNOS on the spinal gray matter of the adult rat decreased, eNOS activity increased. Different from the adult rat, expression of the nNOS in the young rat was maintained until 1 day after SCI, and compared with the adult rat; eNOS activity was increased in the vessels from the damaged gray matter area after 7 days of SCI. iNOS expression was maintained until the 7th day of SCI on the adult rat, but iNOS expression after 7 days of SCI on young rat decreased. The young rat showed relatively less motor disability on the hind limb when compared with the adult rat, and had a rapid recovery. CONCLUSION: Neural protective eNOS activity increased after SCI in the young rat, and neural destructive iNOS expression was more remarkable in the adult rat.     

Improved functional outcome after spinal cord injury in iNOS-deficient mice

STUDY DESIGN: Functional outcome was evaluated following experimental compression-type spinal cord injury (SCI) in wild-type mice and knockout mice, lacking the inducible nitric oxide synthase (iNOS) gene. OBJECTIVES: To evaluate the role of the nitric oxide generating enzyme iNOS in SCI. METHODS: The experimental animals were subjected to an extradural compression of the thoracic spinal cord. Functional outcome was studied during the first 2 weeks post-injury using a scoring system for assessment of hind limb motor function. RESULTS: Injury resulted in initial paraplegia followed by gradual improvement of motor function in most cases. Mice lacking the iNOS gene (iNOS-/-) clearly tended to have a better functional outcome than wild-type mice. The difference was significant on day 14 after injury. CONCLUSION: In accordance with a few earlier experimental studies, showing beneficial effects of pharmacological iNOS inhibition, the present report would indicate a destructive influence of iNOS following spinal cord trauma.     

Anti-apoptotic effect of insulin in the control of cell death and neurologic deficit after acute spinal cord injury in rats

Recent studies confirmed that the new cell survival signal pathway of Insulin-PI3K-Akt exerted cyto-protective actions involving anti-apoptosis. This study was undertaken to investigate the potential neuroprotective effects of insulin in the pathogenesis of spinal cord injury (SCI) and evaluate its therapeutic effects in adult rats. SCI was produced by extradural compression using modified Allen's stall with damage energy of 40 g-cm force. One group of rats was subjected to SCI in combination with the administration of recombinant human insulin dissolved in 50% glucose solution at the dose of 1 IU/kg day, for 7 days. At the same time, another group of rats was subjected to SCI in combination with the administration of an equal volume of sterile saline solution. Functional recovery was evaluated using open-field walking, inclined plane tests, and motor evoked potentials (MEPs) during the first 14 days post-trauma. Levels of protein for B-cell lymphoma/leukemia-2 gene (Bcl-2), Caspase-3, inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) were quantified in the injured spinal cord by Western blot analysis. Neuronal apoptosis was detected by TUNEL, and spinal cord blood flow (SCBF) was measured by laser-Doppler flowmetry (LDF). Ultimately, the data established the effectiveness of insulin treatment in improving neurologic recovery, increasing the expression of anti-apoptotic bcl-2 proteins, inhibiting caspase-3 expression decreasing neuronal apoptosis, reducing the expression of proinflammatory cytokines iNOS and COX-2, and ameliorating microcirculation of injured spinal cord after moderate contusive SCI in rats. In sum, this study reported the beneficial effects of insulin in the treatment of SCI, with the suggestion that insulin should be considered as a potential therapeutic agent.     

Protective effects of extract of Ginkgo biloba (EGb 761) on nerve cells after spinal cord injury in rats

STUDY DESIGN: An experimental animal model was used to assess spinal cord injury following lateral hemitransection at thoracic spinal cord level. OBJECTIVE: To determine whether extract of Ginkgo biloba (EGb) could have a neuroprotective effect in spinal cord injury (SCI) in rats. SETTING: Department of Biological Sciences and Biotechnology, Tsinghua University, China. METHODS: A total of 72 adult rats were divided randomly into three groups: the EGb group, normal saline (NS) group, and sham operation group (sham group). After thoracic spinal cord hemitransection was performed at the level of the 9th thoracic vertebra (T9), rats in the EGb group were given 100 mg/kg EGb 761 daily, while rats in the NS group received NS. The rats in the sham group only underwent laminectomy without spinal cord hemitransection. At various time points after surgery, thoracic spinal cords were sampled and sliced for histochemistry, immunohistochemistry of inducible nitric oxide synthase (iNOS), and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) of apoptotic cells. RESULTS: Myelin staining showed that the area of cavities was small and the demyelinated zones were limited at and around the injury site of the spinal cord in the EGb group, while the area of cavities was large and the demyelinated zones were serious in the NS group. Nissl staining showed that the ratio of bilateral ventral horn neurons (transection side/uninjured side) in the EGb group was higher than that in the NS group (P<0.05). The apoptotic index and the percentage of iNOS-positive cells were lower in the EGb group than in the NS group. Furthermore, the percentage of iNOS-positive cells positively correlated with the apoptotic index (r( 2)=0.729, P<0.01) after SCI. CONCLUSION: This study demonstrated that EGb 761 could inhibit iNOS expression and have neuroprotective effect by preventing nerve cells from apoptosis after SCI in rats.     

Gene expression of inducible nitric oxide synthase in injured spinal cord tissue

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Neurogenesin-1基因促进脊髓损伤后功能修复的实验研究

目的 探讨Neurogenesin-1(Ng1)基因对脊髓损伤后功能恢复的影响.方法 将36只大鼠随机分为实验组和对照组,每组18只.采用改良Allen法制备大鼠胸10脊髓损伤模型后,通过Alzet微泵分别向实验组和对照组持续转染入Ng1重组质粒和空白质粒.术后各时间点BBB评分系统监测大鼠运动功能恢复情况,并于术后第2周和第4周时分别取材,应用神经细胞特异性免疫荧光双标染色和组织学观察Ng1基因对内源性神经干细胞分化的影响以及脊髓组织病理变化情况.结果 自损伤后1周起实验组大鼠的BBB评分明显高于对照组.组织学观察实验组脊髓形态恢复较好逐渐趋于正常.实验组脊髓组织中新分化的神经元细胞数较对照组明显增多,同时新分化的星型胶质细胞数显著减少.结论 Ng1基因能够诱导脊髓损伤后内源性神经干细胞分化为神经元,促进脊髓运动功能的修复.