诱导型一氧化氮合酶反义核酸对脊髓损伤后神经功能的影响

目的　观察诱导型一氧化氮合酶反义核酸 (ASODN iNOS)对大鼠脊髓损伤 (SCI)后神经功能恢复的影响。方法　设计并合成ASODN iNOS ,微量注入大鼠蛛网膜下腔后制备成脊髓压迫伤动物模型 ,伤后 6h用逆转录 聚合酶链反应 (RT PCR)检测iNOSmRNA表达变化 ,2 4h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 ,4周后用电生理、动物行为学和病理学等指标评价神经功能的恢复情况。对照组为正常组、损伤对照组和无义核酸对照组 (NSODN)。结果　SCI后组织中存在iNOS的表达 ,应用ASODN iNOS可以抑制相应酶的表达 ,并可以降低组织中的NO含量和NOS活性 ,改善神经传导功能 ,与损伤对照相比差异有显著性 ,NSODN没有上述作用。结论　脊髓损伤后应用iNOS反义核酸可以使伤后神经功能得到改善。     

Sildenafil improves epicenter vascular perfusion but not hindlimb functional recovery after contusive spinal cord injury in mice

Nitric oxide (NO) is an important regulator of vasodilation and angiogenesis in the central nervous system (CNS). Signaling initiated by the membrane receptor CD47 antagonizes vasodilation and angiogenesis by inhibiting synthesis of cyclic guanosine monophosphate (cGMP). We recently found that deletion of CD47 led to significant functional locomotor improvements, enhanced angiogenesis, and increased epicenter microvascular perfusion in mice after moderate contusive spinal cord injury (SCI). We tested the hypothesis that improving NO/cGMP signaling within the spinal cord immediately after injury would increase microvascular perfusion, angiogenesis, and functional recovery, with an acute, 7-day administration of the cGMP phosphodiesterase 5 (PDE5) inhibitor sildenafil. PDE5 expression is localized within spinal cord microvascular endothelial cells and smooth muscle cells. While PDE5 antagonism has been shown to increase angiogenesis in a rat embolic stroke model, sildenafil had no significant effect on angiogenesis at 7 days post-injury after murine contusive SCI. Sildenafil treatment increased cGMP concentrations within the spinal cord and improved epicenter microvascular perfusion. Basso Mouse Scale (BMS) and Treadscan analyses revealed that sildenafil treatment had no functional consequence on hindlimb locomotor recovery. These data support the hypothesis that acutely improving microvascular perfusion within the injury epicenter by itself is an insufficient strategy for improving functional deficits following contusive SCI.     

Temporal and segmental distribution of constitutive and inducible nitric oxide synthases after traumatic spinal cord injury: effect of aminoguanidine treatment

Nitric oxide (NO) has been shown to play an important role in the pathophysiology of traumatic brain injury (TBI) and cerebral ischemia. However, its contribution to the pathogenesis of traumatic spinal cord injury (SCI) remains to be clarified. This study determined the time course of constitutive and inducible nitric oxide synthases (cNOS and iNOS, respectively) after SCI. Rats underwent moderate SCI at T10 using the NYU impactor device and were allowed to survive for 3, 6, or 24 h and 3 days after SCI (n = 5 in each group). For the determination of enzymatic activities, spinal cords were dissected into five segments, including levels rostral and caudal (remote) to the injury site. Other rats were perfusion fixed for the immunohistochemical localization of iNOS protein levels. cNOS activity was significantly decreased at 3 and 6 h within the traumatized T10 segment and at 3, 6, and 24 h at the rostral (T9) level (p < 0.05). Rostral (T8) and caudal (T11, T12) to the injury site cNOS activity was also decreased at 3 h after injury (p < 0.05). However, cNOS activity returned to control levels within 6 h at T8, T11 and T12 and at one day at T10 and T9 segments. iNOS enzymatic activity was elevated at all time points tested (p < 0.05), with the most robust increase observed at 24 h. Immunostaining for iNOS at 24 h revealed that a significant cellular source of iNOS protein appeared to be invading polymorphonuclear leukocytes (PMNLs). To assess the functional consequences of iNOS inhibition, aminoguanidine treatment was initiated 5 min after SCI and rats tested using the BBB open field locomotor score. Treated rats demonstrated significantly improved hindlimb function up to 7 weeks after SCI. Histopathological analysis of contusion volume showed that aminoguanidine treatment decreased lesion volume by 37% (p < 0.05). In conclusion, these results indicate that (1) cNOS and iNOS activities are regionally and temporally affected after moderate SCI, (2) the early accumulation of PMNLs are a potentially significant source of NO-induced cytotoxic products, and (3) acute aminoguanidine treatment significantly improves functional and histopathological outcome after SCI.     

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.     

Social and environmental enrichment improves sensory and motor recovery after severe contusive spinal cord injury in the rat

Neuropathic pain and motor dysfunction are difficult problems following spinal cord injury (SCI). Social and environmental enrichment (SEE), which models much of the clinical rehabilitation environment for post-SCI persons, is the focus of the current investigation which examines the effects of multiple-housing and the addition of climbing spaces, improved bedding and crawl toys on the sensory and motor recovery following a severe contusive SCI. Efficacy was determined with sensory testing, open-field motor behavioral testing, lesion volume analysis and quantification of brain-derived neurotrophic factor (BDNF) in the lumbar spinal cord with and without SEE provided during the recovery period. Sensory and motor testing were performed weekly for 12 weeks following SCI. SEE significantly and permanently reversed cutaneous allodynia, but not thermal hyperalgesia, to near normal levels. The gross locomotor performance (BBB [Basso, Beattie, and Bresnahan] motor scores) significantly improved about two points. In addition, the BBB subscale scores were significantly improved nearly seven points by the end of the study. SEE also significantly improved foot rotation to normal levels and reduced gridwalk footfall errors nearly 50%, but had no effect on stride length or base of support dysfunctions. SEE significantly increased the total volume of a thoracic segment of cord encompassing the injury site at 12 weeks, by reducing cavitation and increasing both the volume of grey and white matter spared, compared to SCI alone. When BDNF levels were examined in the injured lumbar spinal cord, SEE significantly returned BDNF levels to near-normal. These data suggest that immediate use of SEE after contusive SCI is able to improve overall spinal cell survival and prevent much of the sensory and motor dysfunction that accompanies contusive SCI.     

Post-traumatic moderate systemic hypothermia reduces TUNEL positive cells following spinal cord injury in rat

STUDY DESIGN: A standardized animal model of contusive spinal cord injury (SCI) with incomplete paraplegia was used to test the hypothesis that moderate systemic hypothermia reduces neural cell death. Terminal deoxynucleotidyl transferase [TdT]-mediated deoxyuridine triphosphate [dUTP] nick-end labeling (TUNEL) staining was used as a marker of apoptosis or cell damage. OBJECTIVE: To determine whether or not moderate hypothermia could have a neuroprotective effect in neural cell death following spinal cord injury in rats. SETTING: Kagawa Medical University, Japan. METHODS: Male Sprague-Dawley (SD) rats (n=39) weighing on average 300 g (280-320 g) were used to prepare SCI models. After receiving contusive injury at T11/12, rats were killed at 24 h, 72 h, or 7 days after injury. The spinal cord was removed en bloc and of examined at five segments: 5 and 10 mm rostral to the center of injury, center of injury, and 5 and 10 mm caudal to the center of injury. Rats that received hypothermia (32 degrees C/4 h) were killed at the same time points as those that received normothermia (37 degrees C/3 h). The specimens were stained with hematoxylin and eosin, and subjected to in situ nick-end labeling (TUNEL), a specific method for visualizing cell death in the spinal cord. RESULTS: At 24 h postinjury, TUNEL positive cells (TPC) decreased significantly 10 mm rostral to center of injury in hypothermic animals compared to the normothermia group. At 72 h post-SCI, TPC also decreased significantly at 5 mm rostral, and 5 and 10 mm caudal to the lesion center compared to normothermic animals. At 7 days postinjury, a significant decrease of TPC was observed at the 5 mm rostral and 5 mm caudal sites compared to normothermic animals. CONCLUSION: These results indicate that systemic hypothermia has a neuroprotective effect following SCI by attenuating post-traumatic TPC.     

芬苯达唑对大鼠脊髓损伤后免疫反应和运动功能恢复的影响

目的：观察芬苯达唑对脊髓损伤大鼠的CD45R阳性B细胞、IgG免疫反应以及运动功能恢复的影响。方法将75只成年雌性SD大鼠随机分为假手术组、模型对照组和芬苯达唑组,每组25例。假手术组、模型对照组术前4周给予常规啮齿动物饲料喂食（含18%蛋白质的饲料）,芬苯达唑组术前4周给予加入芬苯达唑的常规啮齿动物饲料喂食。用Allen法构建脊髓损伤模型,分别于术后第1、7、14、21、28天行Basso?Beatti?Bresnahan（BBB）运动功能评估,利用免疫组化检测损伤部位脊髓组织中IgG的表达水平,利用免疫荧光检测脊髓损伤部位CD45R阳性B细胞的信号水平。结果脊髓损伤后,模型对照组和芬苯达唑组的BBB评分均显著低于假手术组（均P＜0.05）,随着时间的延长,两组的BBB运动评分均逐渐有所恢复,但仍低于假手术组;脊髓损伤后第1天,模型对照组与芬苯达唑组的BBB运动评分分别为（3.10±0.29）分、（3.23±0.48）分,差异尚无统计学意义;而在脊髓损伤后的第7、14、21、28天,芬苯达唑组的BBB评分均高于模型对照组,差异均有统计学意义（均P＜0.05）。免疫组化检查证实损伤部位脊髓标本的IgG水平显著升高,第7天开始,芬苯达唑组各个时间点的IgG免疫反应水平均低于模型对照组,差异均有统计学意义（均P＜0.05）。免疫荧光检查证实脊髓损伤后损伤部位脊髓节段CD45R阳性B细胞信号水平显著升高,第7天开始,芬苯达唑组各个时间点脊髓损伤部位的CD45R阳性B细胞的信号水平均低于模型对照组,差异均有统计学意义（均P＜0.05）。结论芬苯达唑预处理可降低脊髓组织中IgG的表达水平及脊髓损伤部位的CD45R阳性B细胞的信号水平,促进脊髓损伤后的神经功能恢复。     

Diffusion tensor imaging predicts hyperacute spinal cord injury severity

Experimental strategies that focus on ventral white matter (VWM) preservation during the hyperacute phase hold great potential for our improved understanding of functional recovery following traumatic spinal cord injury (SCI). Critical comparisons of human SCI to rapidly accumulating data derived from rodent models are limited by a basic lack of in vivo measures of subclinical pathophysiologic changes and white matter damage in the spinal cord. Spinal cord edema and intraparenchymal hemorrhage demonstrated with routine MR sequences have limited value for predicting functional outcomes in SCI animal models and in human patients. We recently demonstrated that in vivo derived diffusion tensor imaging (DTI) parameters are sensitive and specific biomarkers for spinal cord white matter damage. In this study, non-invasive in vivo DTI was utilized to evaluate the white matter of C57BL/6 mice 3 h after mild (0.3 mm), moderate (0.6 mm), or severe (0.9 mm) contusive SCI. In the hyperacute phase, relative anisotropy maps provided excellent gray-white matter contrast in all degrees of injury. In vivo DTI-derived measurements of axial diffusion differentiated between mild, moderate, and severe contusive SCI with good histological correlation. Cross-sectional regional measurements of white matter injury severity between dorsal columns and VWM varied with increasing cord displacement in a pattern consistent with spinal cord viscoelastic properties.     

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。     

Systemically administered interleukin-10 reduces tumor necrosis factor-alpha production and significantly improves functional recovery following traumatic spinal cord injury in rats.

In these studies, we examined the neuroprotective effects of the potent antiinflammatory cytokine interleukin-10 (IL-10) following spinal cord injury (SCI). Neuroprotection was assessed by using behavioral and morphological end points. We hypothesized that injury-induced inflammation contributes to the resulting neuropathology and subsequent loss of function. Therefore, by attenuating injury-induced inflammation, we should promote functional recovery. The New York University device was used to induce moderate SCI and study the resulting inflammatory response and functional consequences of inhibiting this response in rats. We determined that SCI induces the expression of tumor necrosis factor-alpha (TNF-alpha) in the spinal cord and by SCI-activated monocytes isolated from the peripheral circulation. IL-10 (5.0 microg) administered 30 minutes after-injury significantly reduced the expression of TNF-alpha protein in the spinal cord and in vitro by SCI-activated monocytes. Next, we investigated whether IL-10 would improve functional recovery after SCI. Randomized, double-blinded studies demonstrated that a single injection of IL-10 significantly improves hind limb motor function 2 months after injury, as determined by the Basso, Beattie and Bresnahan (BBB) open-field behavioral test. IL-10-treated animals had a mean BBB score of 18.0+/-0.5 (SEM, n = 9) compared with a score of 12.9+/-0.6 (SEM, n = 9) for the saline-treated controls. Morphological analysis demonstrated that IL-10 reduces lesion volume by approximately 49% 2 months after injury. These data suggest that acute administration of IL-10 reduces TNF-alpha synthesis in the spinal cord and by activated macrophages, is neuroprotective, and promotes functional recovery following SCI.     

Behavioral and histological characterization of unilateral cervical spinal cord contusion injury in rats

Most experimental studies of spinal cord injury (SCI) in rats damage the thoracic cord, with the consequent functional loss being due to interruption of long tracts connecting the caudal spinal cord to the rostral nervous system. Less work has been done evaluating injury to the cervical cord, even though it is the most common level of human SCI. In addition to the long tracts, the cervical spinal cord contains the sensory and motor neurons responsible for upper extremity function. The purpose of this study was to further develop a rat model of cervical spinal cord contusion injury using a modified NYU/MASCIS weight drop device. Mild (6.25 mm) and moderate (12.5 mm) C5 unilateral injuries were produced. Behavioral recovery was examined using a grooming test, a paw preference test, a walkway test (The Catwalk), and a horizontal ladder test. Histological outcome measures included sparing at the lesion epicenter, sparing throughout the extent of the lesion, quantification of myelin loss rostral and caudal to the lesion, and motor neuron counts. Compared to controls, animals receiving SCI exhibited injury severity-specific deficits in forelimb, locomotor, and hindlimb function persisting for 6-weeks post-SCI. Histological analysis revealed ipsilateral containment of the injury, and differentiation between groups on all measures except motor neuron counts. This model has many advantages: (1) minimal animal care requirements post-SCI, (2) within subject controls, (3) functional loss involves primarily the ipsilateral forelimb, and (4) it is a behavioral and histological model for both gray and white matter damage caused by contusive SCI.     

Histopathological and behavioral characterization of a novel cervical spinal cord displacement contusion injury in the rat

Cervical contusive trauma accounts for the majority, of human spinal cord injury (SCI), yet experimental use of cervical contusion injury models has been limited. Considering that (1) the different ways of injuring the spinal cord (compression, contusion, and transection) induce very different processes of tissue damage and (2) the architecture of the spinal cord is not uniform, it is important to use a model that is more clinically applicable to human SCI. Therefore, in the current study we have developed a rat model of contusive, cervical SCI using the Electromagnetic Spinal Cord Injury Device (ESCID) developed at Ohio State University (OSU) to induce injury by spinal cord displacement. We used the device to perform mild, moderate and severe injuries (0.80, 0.95, and 1.1 mm displacements, respectively) with a single, brief displacement of <20 msec upon the exposed dorsal surface of the C5 cervical spinal cord of female (180-200 g) Fischer rats. Characterization of the model involved the analysis of the temporal histopathological progression of the injury over 9 weeks using histochemical stains to analyze white and gray mater integrity and immunohistochemistry to examine cellular changes and physiological responses within the injured spinal cord. Accompanying the histological analysis was a comprehensive determination of the behavioral functionality of the animals using a battery of motor tests. Characterization of this novel model is presented to enable and encourage its future use in the design and experimental testing of therapeutic strategies that may be used for human 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.     

中性粒细胞在急性脊髓损伤中作用的实验研究

目的：观察中性粒细胞在脊髓压迫伤中的局部聚集情况及其可能的作用。方法：采用压迫法致大鼠脊髓中度损伤，实验动物分正常大鼠损伤组、低白细胞血症大鼠损伤组和假手术组。观察伤后1、3、6、12、24h伤段脊髓髓过氧化物酶(MPO)活性，记录双下肢运动诱发电位(MEP)，应用斜板试验评价大鼠的运动功能。结果：脊髓压迫伤后1h MPO活性开始升高，3h达到高峰。低白细胞血症组伤后3hMPO活性较对照组明显降低，脊髓运动功能的改善较对照组明显。结论：脊髓损伤后局部中性粒细胞聚集增加，可能参与脊髓继发性损伤。     

Neural circuitry of the adult rat central nervous system after spinal cord injury: a study using fast blue and the Bartha strain of pseudorabies virus

The distribution of retrogradely and transneuronally labeled neurons in the adult rat brain and spinal cord after contusive mid-thoracic spinal cord injury (SCI) was studied using Fast Blue (FB) and the Bartha strain of pseudorabies virus (PRV), respectively. When FB was injected into the distal spinal cord at 2 days after graded SCI at the 10th vertebral level, labeled neurons were consistently found 7 days later in supraspinal areas that normally project to the spinal cord. The number of FB-labeled neurons decreased as the injury severity increased. An inverse correlation between the number of FB-labeled neurons and injury severity was seen in most investigated brain nuclei with coefficient of correlations (r) ranging from -0.84 in the red nucleus to -0.92 in the raphe nuclei. The coefficient of correlation was relatively poor in the motor cortex (r = -0.63), where a mild injury (6.25 g.cm) resulted in a 99% damage of the corticospinal tract. Such a prominent difference between the corticospinal tract and other descending pathways can be related to the difference in location of these pathways within the adult rat spinal cord. When PRV was injected into the right sciatic nerve one month after the injury, labeled cells were consistently identified 5 days later in the spinal cord rostral to the injury and in certain supraspinal regions that regulate autonomic outflow. In these nuclei, the distribution and number of PRV-labeled neurons markedly decreased after SCI as compared to the control group. In contrast, PRV-labeled neurons were inconsistently found in the supraspinal nuclei that contribute to somatic motor outflow in normal controls and no labeling was observed in these nuclei after injury. These results demonstrate that (1) a proportion of neural network across the injured spinal cord has been spared after acute contusive SCI, (2) the proportion of spared axons of a particular pathway is closely correlated to the injury severity and the position of that pathway, and (3) the transneuronal labeling method using PRV may provide a unique approach to investigate multi-synaptic neural circuitry of the central autonomic control after SCI, but its application to the somatic motor system is limited.     

慢病毒介导的脑红蛋白体内基因转染对兔损伤脊髓的作用

【摘要】　目的：观察慢病毒介导脑红蛋白（Ngb）体内基因转染兔损伤的脊髓组织后对后肢运动功能的影响,探讨其作用机制。方法：用球囊压迫法制成兔脊髓损伤（ＳＣＩ）模型96只,随机分为对照组（A组）、生理盐水组（B组）、空载体组（C组）和Ngb慢病毒组（D组）,每组动物24只,A组SCI后无治疗;B组SCI后向脊髓内注射生理盐水;C组SCI后向脊髓内注射空病毒;D组SCI后向脊髓内注射Ngb重组慢病毒。各组分别在1、3、7、14、21d采用BBB运动功能评分系统检测兔后肢运动功能情况;观察损伤脊髓组织内标记荧光的表达;Real-time PCR和Western blot检测Ngb mRNA及其相应蛋白的表达情况,生化方法检测丙二醛（MDA）和一氧化氮（NO）水平。结果：损伤后14d和21d,D组BBB评分明显高于其他3组（P<0.05）,但A、B及C组之间比较无差异（P＞0.05）;C组和D组兔损伤部位脊髓组织均有GFP表达的绿色荧光信号;损伤后7d、14d和21d,D组的Ngb表达与其他3组比较明显增强（P<0.05）;损伤后7d、14d和21d,D组损伤脊髓组织中MDA、NO含量明显低于其他3组（P<0.05）。结论：慢病毒介导脑红蛋白（Ngb）体内基因转染可使Ngb高表达,可能是通过减轻继发性SCI,从而促进SCI后后肢运动功能的恢复。     

低剂量他克莫司治疗大鼠急性脊髓损伤的实验研究

目的：探讨低剂量他克莫司（tacrolimus，又名FK506）对大鼠急性脊髓损伤是否具有神经保护作用。方法：雄性Wistar大鼠72只，随机分为假手术组（12只）、损伤组（30只）和FK506治疗组（30只）。采用Allen’s打击法致伤大鼠T10脊髓，假手术组仅做椎板切除术。FK506治疗组在脊髓损伤后5min一次性经尾静脉注射FK5060．3mg／kg，其余两组以相同方法给予等量生理盐水。致伤后30min、6h、24h、48h、72h取伤段脊髓组织行病理观察及原位末端标记法（TUNEL）检测神经细胞凋亡，伤后1、3、7、14、21d行脊髓功能BBB评分和斜板实验。结果：伤后3、7、14、21d，FK506治疗组斜板实验和BBB评分明显优于损伤组，两组间比较差异有显著性（P〈0．05）；伤后各时间点FK506治疗组脊髓损伤区出血坏死较损伤组轻；伤后6、24、48、72h神经细胞凋亡FK506治疗组较损伤组明显减少，两组间比较差异有显著性（P〈0．05）。结论：在大鼠急性脊髓损伤后早期应用低剂量他克莫司（0．3mg/kg）治疗对神经具有保护作用，可减少神经细胞凋亡，减轻脊髓继发性损伤，促进脊髓功能恢复。