大鼠脊髓急性损务后神经细胞凋亡及相关基因表达

目的：研究脊髓急性损伤后神经细胞的凋亡及相关基因的表达,方法：大鼠脊髓（T8、T9）经中度压迫损伤后,分别在30min,2h,4h,8h,24h,48h,72h,7d,14d和21d处死取材（各间组n=4)。应用HE染色、免疫组化及凋亡细胞原位未端标记法对脊髓组织进行标记。结果：损伤4h后,在损伤段及邻近段可见末端标记阳性神经元,损伤段灰质中阳性细菌数8h达高峰,24h白质中阳性胶质细胞数量达高峰。相邻节段阳性细胞数72h达高峰。损伤后P53及Bax大量表达,而Bcl-2仅少量表达。结论：脊髓损伤后神经细胞的凋亡发损伤期的重要病理变化。     

脊髓急性损伤后神经细胞凋亡的时相和空间分布特点

目的 研究脊髓急性损伤后神经细胞的凋亡及其时相和空间特点。方法 大鼠脊髓（T8,9）经中度压迫损伤后,分别在30min、2h、4h、8h、24h、48h、72h、7d、14d、和21d处死取材（n=4)。应用HE、Nissl染色及凋亡细胞原位末端标记法对脊髓组织进行标记。结果 损伤4h后,在损伤段及邻近段可见末端标记阳性神经细胞,损伤段灰质中阳性细胞数8h达高峰,24h白质中阳性胶质细胞数量达高峰。相邻节段阳性细胞数量在72h达高峰。阳性细胞以白质中胶质细胞为主,主要分布于相邻节段。结论 脊髓损伤后神经细胞凋亡是继发损伤期的重要病理变化,并有其时相和空间分布特点。     

大鼠急性脊髓损伤后细胞凋亡的时空分布特点

目的：研究急性脊髓损伤后神经细胞凋亡的分布特别及其意义。方法：Wistar雌性大白鼠54只，使用改良Alien法制作急性脊髓损伤模型，分别于术后l、4、8、24、72h、7、14及2ld处死取材(每时间点n=6)。应用HE染色及凋亡细胞原位末端标记法(TUNEL)对脊髓组织进行标记。结果：损伤后4h，在损伤段及邻近段可见末端标记的阳性神经细胞，损伤段灰质中阳性细胞数24h达高峰，72h白质中阳性胶质细胞数量达高峰。相邻节段阳性细胞数量在72h达高峰。灰质中神经元及胶质细胞均有阳性表达，但以胶质细胞为主。结论：脊髓损伤后神经细胞凋亡是继发损伤期的重要病理变化，并有其时相和空间分布特点.     

兔脊髓冲击伤后神经细胞Bcl-2及Bax基因表达与原位末端标记法检测凋亡的比较

目的 检测兔脊髓冲击伤后早期神经细胞Bcl-2及Bax基因表达,并与原位末端标记检测的基因断裂作比较,评价两者在检测脊髓神经细胞的凋亡方面的意义和一致性.方法 建立50只T9,10段脊髓损伤的兔脊髓冲击伤模型,随机分为5组(n=10),分别在伤后4、12、24、48、72 h不同时间点,分别取各组脊髓组织检测Bax、Bcl-2的表达,并与原位末端标记检测细胞凋亡进行比较,另取10只家兔作对照组.结果 Bax在伤后4h呈阳性表达,表达高峰在伤后24～48 h,Bcl-2在伤后12h呈阳性表达,表达高峰亦在伤后24～48 h,而但表达强度始终弱于Bax;TUNEL检测的基因断裂的变化趋势与Bax趋势相似.结论 兔脊髓冲击伤后早期促进凋亡因子表达占主导,而保护性因子的表达相对不足,基因断裂,促进脊髓神经细胞凋亡.     

大鼠急性脊髓损伤后Caspase-3、Cathepsin B的表达

[目的]研究大鼠急性脊髓损伤后Caspase-3、Cathepsin B的表达,并初步探讨Caspase-3、Cathepsin B在脊髓损伤后表达的意义.[方法]将78只成年健康SD大鼠按Nystrom法建立大鼠脊髓(T8 、T9)急性压迫损伤模型, HE染色观察脊髓组织病理学变化,免疫组化测定各时间点Cathepsin B、Caspase-3 的表达变化,原位末端脱氧核糖核酸转移酶介导的脱氧尿苷三磷酸(dUTP) 标记法(TUNEL 法) 检测神经细胞的凋亡水平.[结果]免疫组化结果显示正常及假手术组大鼠脊髓神经细胞中Caspase-3,Cathepsin B,TUNEL阳性细胞较少;在脊髓损伤后3 d Cathepsin B阳性细胞数明显增多,5 d达高峰,7 d未见明显衰减.Caspase-3阳性细胞数在脊髓损伤后8 h明显增多,3 d达高峰,7 d表达减弱.TUNEL阳性细胞数也在8 h明显增多,3 d达高峰,7 d表达减弱.Cathepsin B阳性细胞形态及表达的部位均与Caspase-3阳性细胞、TUNEL阳性细胞差别较大.[结论]Caspase-3参与了脊髓损伤细胞凋亡的调节,Cathepsin B则可能通过炎性细胞为媒介参与了脊髓继发性损伤.     

bcl-2和bax基因与细胞凋亡的关系及在脊髓损伤中的作用

目的探讨bcl2和bax基因与细胞凋亡的关系及在脊髓损伤中的作用。方法采用Allen法挫伤大鼠T10节段脊髓,随机分为7组,其中6组为实验组,1组为对照组,每组在SCI后2、4、8、24h、3、7d取材,每一时间点4只。免疫组织化学法检测bax和bcl2基因表达,采用原位末端标记法检测凋亡细胞。结果正常组大鼠脊髓中未见凋亡细胞。实验组在损伤2h出现阳性细胞,伤后8h阳性细胞数目达高峰为84.53±8.00,以后逐渐减少。bax基因表达的高峰也在伤后8h为0.311±0.012,说明bax基因促进了细胞的凋亡,而此时bcl2基因开始出现表达增多,至伤后24h表达达高峰,之后缓慢降低,而与此相对应的是细胞凋亡开始逐渐减少(P<0.01)。结论凋亡相关基因bax与bcl2可能参与了脊髓继发性损伤,细胞凋亡在脊髓继发性损伤过程中起着关键性作用。     

甲基强的松龙对大鼠脊髓损伤后神经细胞凋亡的影响及其机理

目的研究甲基强的松龙(MP)对大鼠横断性脊髓损伤(SCI)后神经细胞凋亡的影响及其作用机理.方法60只成年Wistar大鼠随机分成正常对照组、脊髓损伤组和MP治疗组,每组20只,MP治疗组在横断T10脊髓组织后30min经尾静脉给予MP治疗,损伤组和对照组未予任何治疗.MP治疗组和脊髓损伤组大鼠于脊髓损伤后8h、24h、3d和1周取材,采用透射电镜、TUNEL染色观察细胞凋亡情况,采用免疫组织化学染色观察Fas、半胱氨酸蛋白酶(caspase)-8和caspase-3在SCI前后的变化情况,采用改良Tarlov评分方法观察大鼠后肢运动功能.结果SCI后24h大鼠后肢运动功能逐渐恢复,MP治疗组大鼠的后肢运动功能恢复优于损伤组,7d后尤其明显.TUNEL染色和电镜检查证实SCI后8h即有凋亡细胞出现,其中既有神经元也有胶质细胞3d凋亡细胞数达到高峰;7d仍有凋亡细胞存在,但已明显减少;各时间点治疗组凋亡细胞数量明显少于损伤组(P＜0.05).治疗组和损伤组在SCI后8h可以检测到少量的Fas和caspase-8阳性神经元及胶质细胞,Fas和caspase-8的表达在SCI后3d达到高峰,7d表达下降,各时间点治疗组的Fas和caspase-8灰度值明显大于损伤组,二者有显著性差异(P＜0.05).治疗组和损伤组caspase-3的表达在SCI后8h均逐渐增加(与对照组相比),7d达到高峰,治疗组灰度值大于损伤组,但二者无显著性差异.结论MP能抑制大鼠脊髓横断性脊髓损伤后的神经细胞凋亡,但不能推迟细胞凋亡出现的高峰时间;MP抑制细胞凋亡的途径可能通过非特异性抑制Fas和caspase-8的表达来实现.     

大剂量甲基强的松龙对大鼠急性脊髓损伤后神经细胞Bcl-2表达及细胞凋亡的影响

目的：观察大剂量甲基强的松龙（MP）治疗对大鼠急性脊髓损伤（ASCI）后神经细胞凋亡及凋亡基因Bcl-2的影响。方法：选取48只雌性SD大鼠随机等分为2组,对照组与治疗组,按Nystrom法制备大鼠急性脊髓损伤模型。治疗组伤后30min经腹膜腔注入MP30mg／kg,以后每小时腹膜腔注入MP5．4mg／kg,维持24h;对照组应用生理盐水替代MP,处理方法同治疗组。两组分别于伤后4、8h及1、3、7、14d灌注固定后取材。免疫组织化学检测损伤段脊髓内Bcl-2蛋白表达,TUNEL检测细胞凋亡,染色结果应用图像分析仪进行半定量分析。结果：大鼠ASCI后4h即可见脊髓内TUNEL阳性细胞,8h表达达高峰,此后表达量逐渐下降,14d时仍可见少量阳性细胞。凋亡相关蛋白Bcl-2在伤后4h即可见表达,伤后1d达高峰,伤后14d仍有表达,与对照组相比,治疗组伤后8h、1d和3d时凋亡细胞数减少有统计学意义,伤后8h和1d Bcl-2蛋白表达增高有统计学意义。结论：大剂量甲基强的松龙治疗可抑制大鼠ASCI后神经细胞凋亡,并增加凋亡相关蛋白Bcl-2的表达：     

脊髓损伤后凋亡调控基因Bcl-2、Bax的表达及意义

目的:观察探讨大白鼠脊髓损伤后细胞凋亡及调控基因Bcl-2、-Bax的表达及意义.方法:28只SD大鼠随机分为7组,Allen‘s法致伤脊髓,于术后4、8、24、48、72、168h采集脊髓标本,1组作为对照组,分别行HE染色、TUNEL染色和免疫组化技术检测Bcl-2、Bax的表达.结果:TUNEL染色显示有神经元和胶质细胞凋亡.Bcl-2在术后4h开始出现阳性表达,24h达高峰.Bax术后4h出现阳性表达,8h时达高峰.结论:脊髓损伤后存在神经元和胶质细胞的凋亡,Bcl-2、Bax基因对调控细胞凋亡可能具有重要作用.     

牵张性脊髓损伤后神经细胞中Caspase-3表达及其作用的实验研究

目的:观察大鼠牵张性脊髓损伤后脊髓神经细胞中半胱氨酸天冬氨酶3(Caspase-3)的表达及其在神经细胞凋亡中的作用。方法:大鼠脊髓T13~L2经牵张损伤,皮层体感诱发电位监测P1-N1波幅下降至术前波幅70%后维持10m in,分别于术后6h、1、4、7、14、21d处死取材。采用流式细胞仪、原位末端脱氧核苷酸转移酶介导的生物素脱氧尿嘧啶核苷酸缺口末端标记法(TUNEL法)、免疫组织化学检测等方法观察大鼠脊髓神经细胞中Caspase-3表达变化及神经细胞凋亡情况,测定Caspase-3活性。结果:脊髓损伤后神经细胞凋亡率、TUNEL阳性细胞数、Caspase-3免疫组织化学阳性表达及Caspase-3活性测定均较空白对照组及椎板切除组显著升高(P<0.05或0.01),前三项指标改变趋势大致相同,均为术后7d达高峰,而Caspase-3活性则术后4d达高峰。结论:大鼠牵张性脊髓损伤后神经细胞中Caspase-3表达增高、Caspase-3活性增强,是检测神经细胞凋亡的早期生物学指标,对认识脊髓损伤机制具有一定的意义。     

大鼠脊髓急性损伤后bax和bcl—2的表达

目的：检测大鼠脊髓损伤后凋亡相关基因的表达,以探讨神经细胞凋亡的分子机制。方法：大鼠脊髓（T8．9）经中度压迫损伤后,分别在30min、2h、4h、8h、24h、48h和72h处死取材（n=6)。主要应用免疫组化及原位杂交技术对脊髓组织进行标记,以检测bcl-2和bax的表达。结果：损伤4h后bax蛋白大量表达,而bcl-2蛋白仅有少量表达,bcl-2 mRNA未见表达。结论：脊髓损伤后凋亡基因bax大量表达,并可能在神经细胞的凋亡过程中起重要作用。     

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.     

Microglia inhibition is a target of mild hypothermic treatment after the spinal cord injury

STUDY DESIGN: A basic study using a spinal cord injury (SCI) model in rats. OBJECTIVES: The effect of mild hypothermic treatment on histological changes and motor function after a rat spinal cord compression injury was assessed. METHODS: Mild spinal cord compression was performed at the eleventh thoracic vertebral level by a 20 g weight for 20 min. Rats in the mild hypothermic model were kept at a body temperature of 33 degrees C and rats in the normothermic group were kept at 37 degrees C for 1 h from beginning of compression. Motor function was evaluated by measuring the frequency of standing. Microglia were stained by isolectin B4 and observed in the compressed portion of the spinal cord. The amount of tumor necrosis factor-alpha (TNF-alpha) in the compressed spinal cord was measured by the ELISA method. RESULTS: In the normothermic rats, microglia proliferated up to 72 h after the compression. Proliferation was substantially inhibited at 48 and 72 h after compression in the hypothermic rats. The motor function of the hypothermic rats improved at 48 and 72 h after the compression, whereas no improvement was seen in the normothermic rats. The amount of TNF-alpha in the compressed portion of the spinal cord was lower in hypothermic rats compared with normothermic rats throughout the experiment. CONCLUSIONS: These results suggest that hypothermic treatment is effective for the amelioration of delayed motor dysfunction via inhibition of microglial inflammatory responses.     

Optimal treatment timing to attenuate neuronal apoptosis via Bcl-2 gene transfer in vitro and in vivo

Although Bcl-2 gene transfer can rescue cells from neuronal apoptosis, the temporal relationship between treatment initiation time and effectiveness is unknown. The purpose of present study is to investigate the optimal treatment timing of Bcl-2 gene transfer in saving cells after neural insults. Bcl-2 gene transfer was mediated by recombinant adenovirus carrying human bcl-2 oncogene (Adv-Bcl-2). Adenovirus carrying beta-galactosidase gene (Adv-Bgal) served as a control. A serum withdrawal model of NSC-19 cell culture was used to induce apoptosis in vitro. At various time points before or after serum withdrawal, the motor neuron cells (NSC-19 cells) were infected with either Adv-Bcl-2 or Adv-Bgal. At 72 h after serum withdrawal, the number of apoptotic cells and DNA fragmentation were examined to evaluate the effect of Bcl-2 gene transfer. A weight-drop spinal cord injury model in rats was used as in vivo model. At various time points before or after experimental spinal injury, virus solution, including Adv-Bcl-2 or Adv-Bgal, was injected at the spinal cord in injured rats. The degree of cord injury was measured at 72 h after injury. TUNEL staining was performed to count cells that have undergone DNA damage in sections. Bcl-2 protein overexpression was confirmed by immunostaining both in vitro and in vivo model. In vitro, Adv-Bcl-2 infection produced a less prominent DNA laddering pattern. Adv-Bcl-2 infection between 24 h before and 4 h after serum withdrawal significantly reduced the apoptotic cell death. In vivo Adv-Bcl-2 injection immediately after injury effectively suppressed the injury lesion by blocking DNA fragmentation and irreversible cellular injury. Our data demonstrate that earlier initiation of Bcl-2 gene transfer can produce improved neural cell rescue following neural insults. These results stress important temporal considerations in future gene therapy strategies for spinal cord injury.     

bcl-xL基因转染对脊髓损伤半胱氨酸蛋白酶-3表达的影响

目的 探讨bcl—xL基因转染对大鼠脊髓损伤Caspase-3表达的影响和对神经细胞的保护作用。方法 制备大鼠胸段脊髓T8,9压迫损伤模型，随机分为2组：对照组．bcl—xL组，将阳离子脂质体质粒混合后直接注入大鼠损伤脊髓，伤后1、3和7d利用半定量逆转录-聚合酶链式反应（RT—PCR）和免疫组织化学检测bcl—xL和Caspase-3表达情况；TUNEL法检测细胞凋亡，观察对神经细胞的保护作用。结果 与对照组相比，bcl—xL组各时间段Caspase-3表达明显降低（P〈0．05），TUNEL阳性凋亡的神经细胞明显减少（P〈0．05）。结论 外源性bcl—xL基因体内转染在损伤脊髓的过度表达可减少脊髓不完全性损伤后凋亡，可能与其下调Caspase-3的有关。     

大鼠脊髓三种不同损伤后神经细胞凋亡的实验比较

目的了解三种不同脊髓机械性损伤对继发性神经细胞凋亡的影响。方法采用脊髓挫伤、持续性占位、脊髓横断三种大鼠损伤模型,在伤后1、4、7d观察损伤断面神经细胞凋亡现象。结果脊髓挫伤组:灰质三个时间组的凋亡指数波动明显,灰质中凋亡指数4d时最高;白质中凋亡细胞除背侧束外腹侧束也存在;另外细胞凋亡以少突胶质细胞凋亡为主。脊髓持续性占位损伤组:灰质、白质细胞凋亡指数在4d和7d组中差异无显著性意义(P>0.05),白质凋亡细胞在受压的背侧束、外侧束为主。脊髓横断损伤组:灰质、白质在三个时间组中均有大量凋亡细胞。结论大鼠脊髓损伤后神经细胞虽然存在主动死亡(细胞凋亡)方式,但凋亡在时间和部位上与损伤类型、损伤部位、损伤程度有关。     

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。     

Evidence for a neural source of acute accumulation of serotonin in platelets in the injured spinal cord of rats. An experimental study using 5,6-dihydroxytryptamine treatment

It was found previously that large numbers of platelets showing high serotonin (5-hydroxytryptamine; 5-HT) immunoreactivity appeared in hemostatic plugs at the traumatized cord segment in the acute phase of a trauma. In order to determine the origin of 5-HT in the platelets, we investigated the 5-HT immunoreactivity of platelets accumulating in hemostatic plugs at the traumatized spinal cord segment at 5 minutes after injury. This investigation was carried out by light and electron microscopic immunohistochemistry in rat spinal cord pretreated with 5,6-dihydroxytryptamine (5,6-DHT). The hemorrhagic lesion formed at the neural 5-HT-depleted spinal cord segment was completely 5-HT immunonegative, while platelets in lesions in cord segments of control animals or rostral to the injection site of 5,6-DHT in experimental animals where neural 5-HT was not depleted were 5-HT immunoreactive. The results strongly suggest that a significant amount of 5-HT is released from neural elements at the injury site and is transiently incorporated into the platelets in situ.     

慢性脊髓压迫及减压后运动诱发电位及病理学改变

目的探讨脊髓慢性压迫及减压后神经病理学及运动诱发电位(MEP)的变化.方法选用 54只SD大鼠,随机分为对照组,轻、中、重压迫组和减压组.应用磁刺激MEP各组行30 min、6 h和1、2、4周动态观察.用HE染色观察脊髓的组织学变化.结果轻度压迫组MEP潜伏期在损伤后30 min及6 h比术前分别延长0.29倍和0.32倍,至4周恢复,与术前相比,伤后30 min和6 h中度压迫组MEP潜伏期延长0.83倍和0.88倍,重度组延长1.14倍和1.22倍,减压后MEP潜伏期分别缩短了0.21倍和0.23倍.结论轻和中度压迫组的病变是可逆的,而重度压迫导致神经细胞和运动功能的不可逆改变.MEP能反映脊髓受损程度,可作为评价减压效果的客观指标.