蛇毒神经生长因子对大鼠脊髓损伤后Caspase-3表达影响

目的 探讨大鼠脊髓损伤后应用蛇毒神经生长因子对Caspase-3表达的影响.方法 将55只成年SD雄性大鼠随机分为蛇毒神经生长因子组（A组）、生理盐水组（B组）、假手术组（C组）,按改良Allen打击法建立大鼠脊髓不完全损伤模型,通过动物神经运动功能BBB评分评价神经损伤程度及神经功能恢复情况;脊髓损伤后不同时间点（6 h、1 d、3 d、7 d、14 d）取材,HE染色观察损伤脊髓组织病理变化,免疫组化染色检测Caspase-3阳性细胞的表达,来比较分析两组的差异性.结果 HE染色镜检发现脊髓组织病理学改变A组明显轻于B组;BBB评分A组相对B明显提高,差异有显著性意义（P〈0.05）.A组和B组均发现凋亡细胞及Caspase-3表达,神经细胞凋亡指数及Caspase-3表达均为B组〉A组（P〈0.05）.结论蛇毒神经生长因子能抑制大鼠脊髓损伤后Caspase-3表达及细胞凋亡,能改善脊髓损伤后的功能表现.     

蛇毒神经生长因子对大鼠坐骨神经损伤功能修复的时效作用研究

为研究蛇毒神经生长因子 ( SNGF)对大鼠坐骨神经损伤的修复的时效作用 ,作者应用 Wistar大鼠 5 0只建立大鼠坐骨神经钳夹损伤模型 ,随机分为单纯损伤组、生理盐水对照组、SNGF治疗用药 1 4、 2 1、 2 8天组 ,每组 1 0只。 SNGF治疗各组按实验模型制备处理后 ,即刻在损伤神经周围肌肉注射 SNGF ( 90 0 Bu/kg) ,以后每天肌注 1次 ,连续给药 1 4、 2 1和 2 8天 ,而生理盐水对照组每天肌注等量生理盐水。结果通过展爪反射观察到 ,1 4天组术后 1 1天开始恢复 ,平均恢复时间 1 6天 ;2 1天组术后 1 1天开始恢复 ,平均恢复时间 1 5天 ;2 8天…     

三七总皂苷对脊髓损伤大鼠运动功能恢复的作用

目的：探讨三七总皂苷对大鼠脊髓损伤（SCI）后运动功能恢复的作用。方法：正常SD大鼠随机分为5组（n=8）：正常对照组（Normal）、假手术组（Sham）、脊髓损伤（SCI）和脊髓损伤+三七总皂苷组（PNS）（n=8）。所有大鼠分别在造模前及造模后第1、3、7、14、21和28天接受运动功能评分（BBB）和运动诱发电位（MEP）检查,观察大鼠后肢运动功能的恢复情况。结果：造模后,Sham组、PNS组、SCI组BBB评分低于正常;MEP波幅低于正常;潜伏期较正常延长。PNS组与同期SCI组比较,第7、14、21、28天的BBB评分差异有统计学意义（P<0.05）;第7天、14天、21天、28天,MEP检查波幅（Amp）和潜伏期（Lat）组内有显著差异,并且与同期SCI组比较差异有统计学意义（P<0.05）。结论：三七总皂苷可促进大鼠SCI后运动功能的恢复。     

神经生长因子对大鼠视觉诱发电位的影响

目的和方法：本研究主要通过电生理方法,测定经CS2所致视神经损害的大鼠在治疗前后视觉诱发电位的变化,以证实神经生长因子对受损神经的治疗效果。结果：大鼠视神经损伤模型经神经生长因子治疗20d后,模式反转诱发电位和闪光诱发电位的潜伏期与对照组相比均有明显的缩短,并有量－效关系。结论：神经生长因子能明显改善视神经传导功能,提示神经生长因子对视神经损伤有一定的治疗作用。     

不同训练方法对大鼠骨折后脊髓功能恢复的影响

摘要 目的：分析不同训练方法对大鼠骨折后脊髓功能恢复的影响。方法：随机选取40只Sprague Dawley (SD)大鼠,建立骨折合并脊髓损伤模型,另取10只大鼠作为正常组。将建模成功的SD大鼠随机分为模型组、减重平板训练组、游泳训练组和转笼训练组。分别于损伤前和损伤后对大鼠的运动功能进行评测;术后35 d对大鼠的运动诱发电位（(motor evoked potentials, MEP）、脑源性神经生长因子（brain-derived neuotrophyic factor, BDNF）、神经元特异性烯醇化酶（neuron-specific enolase, NSE）和脊髓组织Cleaved Caspase-3表达量、肌纤维横截面积和直径进行评测。结果：损伤后,手术组大鼠运动功能评分均降低;经不同方式训练后,大鼠的运动功能评分均上升,14 d～35 d数据差异有统计学意义（P＜0.05）。术后35 d,与模型组相比,训练组大鼠运动诱发电位潜伏期均缩短,波幅、BDNF和NSE表达量、肌纤维横截面积和直径均增大,Cleaved Caspase-3表达量均降低,14 d～35 d数据差异有统计学意义（P＜0.05）。其中,减重平板训练组各指标检测结果最优。结论：三种训练方式均可促进大鼠骨折后脊髓功能恢复,其中减重平板训练组恢复效果＞游泳训练组＞转笼训练组。     

急性脊髓损伤后大鼠电刺激运动诱发电位的变化

目的：比较不同程度脊髓损伤（SCI）与运动诱发电位（MEP）变化之间的关系,探索MEP检查在SCI早期诊断及预后中的价值。方法：27只雄性SD大鼠以改良Allen‘s打击法致伤T8－T9脊髓,按打击冲量随机分为空白对照组（n=5),SCI A组（50gcf,n=8),SCI B组（70gcf,n=8)和SCI C组（100gcf,n=6),采用单极经皮层电刺激,分别于损伤前、伤后即刻、15min、30min、1h、3h和6h连续观察scMEP变化,并计算脊髓出血坏死区域占脊髓横截面积的比率。结果：对照组MEP无显著改变,SCI A组和SCI B组动物MEP早成份波幅立即减低或消失,以后有所恢复,晚成份波消失后未再出现。SCI C组动物除2只大鼠SCI后MEP仍有所恢复外,其余动物再未出现MEP波。脊髓损伤随打击冲量增大而增加,与伤后1h scMEP最大波幅呈显著相关（r=-0.821)。结论：SCI后scMEP的变化程度与打击冲量和脊髓病理损伤面积相关,提示scMEP可以作为一种脊髓功能检测的客观指标。     

诱发电位评价脑组织血流量的实验研究

目的：观察实验性大鼠脑损伤后不同时相点大脑皮层体感诱发电位（sensorysomaticevoked potentials,ssep)和局部血流量（regional cerebral blood flow,rCBF)的变化。方法：用流体冲击装置制作中度脑损伤模型SYD4200型神经诱发电位诊断系统监测皮层体感诱发电位,氢清除测定大脑局部血流量。结果：中度脑损伤后rCBF明显低于伤前和正常对照组;大脑皮层体感诱发电位的潜伏期明显延长。结论：SEP的变化与脑血流量有着一定的关系,一定程度上SEP的变化可反映脑损伤后血流量的变化。     

骨髓间充质干细胞经BDNF基因修饰后移植治疗大鼠半横断脊髓损伤的电生理研究

目的采用电生理的研究方法,观察脑源性神经营养因子(BDNF)基因修饰的骨髓间充质干细胞对脊髓损伤的修复作用。方法随机将大鼠分成3组:空白组10只(只切除椎板,暴露脊髓硬脊膜);SCI组10只;SCI术后细胞移植组10只;从以上三组大鼠随机抽取8只于细胞移植后1 d、7 d、14 d、21 d、30 d、60 d进行SEP(皮层体感诱发电位)、MEP(运动诱发电位)等电生理检测技术,并观察大鼠的运动评分恢复程度。结果细胞移植4d后,大鼠饮食和活动开始增加;后肢变化过程如下:损伤后1~4 d损伤侧后肢迟缓性瘫痪,拖地行走,损伤对侧后肢由损伤初期的运动减弱逐渐恢复,损伤后5~9 d损伤侧后肢痉挛性瘫痪;10~14 d损伤侧下肢恢复少量活动,损伤对侧后肢恢复至较损伤前稍弱的状态;15~21 d损伤侧后肢活动能力较之前有明显改善,至30 d损伤侧后肢活动能力及肌张力恢复程度最明显,30 d以后无更明显改善。免疫组化发现损伤处诱导标记的骨髓间充质干细胞存活,行为学观察发现细胞移植改善了损伤大鼠运动能力。结论骨髓间充质干细胞经BDNF基因修饰后可以促进脊髓损伤大鼠的神经再生及部分传导功能恢复。     

神经生长因子对PC12细胞脂多糖损伤的保护作用及其机制

目的：细胞水平研究神经生长因子（NGF）对大鼠嗜铬细胞瘤细胞株（PC12细胞）脂多糖（LPS）损伤后的保护作用以及核转录因子（NF-κB）的活性影响,探讨药物作用机制。方法：PC12细胞常规培养后,建立LPS损伤模型,随后MTT观察不同浓度的LPS对PC12细胞损伤及NGF对LPS损伤的保护作用,同时用倒置显微镜和荧光显微镜下观察细胞状态,最后RT-PCR检测NF-κB的含量。结果：①PC12细胞LPS损伤有浓度梯度,随着LPS浓度的增加,PC12细胞的存活率不断下降;LPS损伤的同时加入不同浓度NGF,LPS损伤均有明显的改善。②显微镜观察显示PC12细胞形态学上的改变,表明NGF对LPS损伤有保护作用。③RT-PCR结果显示,LPS损伤细胞的NF-κB的相对表达量明显高于正常对照细胞,而药物治疗组的NF-κB表达量则接近于正常细胞。结论：目前,神经生长因子在脑内炎症后的细胞修复作用报道甚少,而本实验研究神经生长因子对PC12细胞LPS损伤起到保护作用,尤其是损伤后再修复作用,且其作用机制可能与NF-κB信号通路的调控有关。     

人参皂甙Rd通过调节SNI大鼠背根神经节钠、钾电流抑制痛敏

目的：观察人参皂甙Rd（ginsenoside Rd）对大鼠坐骨神经分支选择性损伤（spared sciatic nerve injury,SNI）引起的痛敏的影响及其作用机制。方法：坐骨神经分支选择性损伤术后7天,观察腹腔注射不同浓度人参皂甙Rd后大鼠后足的机械性缩足反应阈值（paw withdrawl mechanical threshold,PWMT）的变化;在术后7天,急性分离并取出大鼠腰4和腰5段背根节,对整节DRG上的中小型神经元运用全细胞膜片钳技术进行记录。结果：坐骨神经分支选择性损伤术后7天,大鼠出现明显的机械性痛敏,腹腔注射5 mg/ml和10 mg/ml的人参皂甙Rd能剂量依赖性的翻转大鼠机械性痛敏;坐骨神经分支选择性损伤能明显地增大SNI大鼠DRG中小型神经元上的钠电流以及减小电压依赖性钾电流,而100μM人参皂甙Rd能有效翻转该钠、钾电流的变化。结论：人参皂甙Rd能有效地改善坐骨神经分支选择性损伤引起的机械性痛敏,其机制可能与人参皂甙Rd明显地调节SNI大鼠DRG中小型神经元上的电压依赖性钠、钾电流有关。     

Whole-body vibration therapy does not improve the peripheral nerve regeneration in experimental model

Objectives:Whole-body vibration (WBV) is commonly used to improve motor function, balance and functional performance, but its effects on the body are not fully understood. The main objective was to evaluate the morphometric and functional effects of WBV in an experimental nerve regeneration model.Methods:Wistar rats were submitted to unilateral sciatic nerve crush and treated with WBV (4-5 weeks), started at 3 or 10 days after injury. Functional performances were weekly assessed by sciatic functional index, horizontal ladder rung walking and narrow beam tests. Nerve histomorphometry analysis was assessed at the end of the protocol.Results:Injured groups, sedentary and WBV started at 3 days, had similar functional deficits. WBV, regardless of the start time, did not alter the histomorphometry parameters in the regeneration process.Conclusions:The earlier therapy did not change the expected and natural recovery after the nerve lesion, but when the WBV starts later it seems to impair function parameter of recovery.     

Lack of physiological stimulation induces decreased proteolytic activity in nerve terminals

The effect of optic nerve transsection on proteolytic degradation of axonally transported proteins in the superior colliculus of the rabbit was studied. Proteolysis of labeled proteins was determined in vitro in small pieces of the superior colliculus. Within 2 hours after sectioning the optic nerve there was a decreased degradation of slowly transported labeled proteins in the nerve terminals in the superior colliculus.Special Issue dedicated to Prof. Holger Hydén.     

Physical properties and biocompatibility of a porous chitosan-based fiber-reinforced conduit for nerve regeneration

Porous fiber-reinforced chitosan nerve conduits were fabricated from chitosan yarns and a chitosan solution by combining an industrial braiding method with a mold casting/lyophilization technique. The conduits were permeable to molecules ranging in molecular size from 180 Da (glucose) to 66,200 Da (BSA). The compressive load of the reinforced conduits was significantly higher than that of a non-reinforced control conduit at equal levels of strain. The tensile strength of the reinforced conduits was also increased from 0.41 ± 0.17 to 3.69 ± 0.64 MPa. An in vitro cytotoxicity test showed the conduits were not cytotoxic to Neuro-2a cells. Preliminary in vivo implantation testing indicated that the conduits were compatible with the surrounding tissue. Aijun Wang and Qiang Ao contributed equally to this work.     

Induction of the high-affinity nerve growth factor receptor on embryonic chicken sensory nerve cells by elevated potassium

Culture medium with elevated K⁺ has been shown to enhance the survival of neurons isolated from several different regions of the nervous system. Nerve growth factor binds to binding sites on sensory and sympathetic neurons through two sites, one of high-affinity (K _d13×10^–11 M) and the other of low-affinity (K _d22×10^–9 M). Equilibrium binding data generated on dissociated cells derived from E9 chicken embryo dorsal root ganglia, has shown that there is a two-fold increase in the number of high affinity (type I) receptors, with no effect on the affinity, when cells are incubated for 2 hours in buffer containing 59 mM K⁺. There does not appear to be a significant change in the affinity or the number of low-affinity binding sites. This two-fold increase in type I receptors is dependent on temperature, Ca²⁺, and active protein synthesis. There does not appear to be an intracellular pool of the type I receptor sufficient to account for this increase. The induction is not observed on sensory nerve cells cultured in 59 mM K⁺ for 24 hours, either in the presence or absence of nerve growth factor. Additionally, the induction in the number of type I receptors requires that both nerve growth factor and K⁺ be present simultaneously. Taken in total, this data suggests that there may be a critical period in which the sensory neurons require nerve growth factor exposure to respond. Evidence is presented which indicates that nerve growth factor responsive cells are able to elicit neurites after an acute exposure to nerve growth factor of as little as 4 hours. Finally, there is an approximate two-fold decrease in the concentration of nerve growth factor needed to elicit maximal fiber outgrowth, consistent with the two-fold increase in the number of type I receptors.Abbreviations NGF nerve growth factor - 7S NGF the high molecular weight form of NGF - NGF the -subunit of 7S NGF - ¹²⁵I-NGF ¹²⁵I-labeled NGF - mNGF–_rAb polyclonal rabbit IgG raised against mouse NGF - DRG dorsal root ganglia - K_d the equilibrium dissociation constant - N the maximal number of binding sites for the ligand NGF - NGFR the biologically relevant receptor through which the neurite outgrowth and neuron survival are mediated - GBS Gey's balanced salts - HKGBS high K⁺ GBS - PBG phosphate buffered GBS - HKPBG high K⁺ PBG - CFHKPBG Ca⁺² free high K⁺ PBG - PBG-cyt c PBG containing 2 mg/ml cytochrome c - HKPBG-cyt c HKPBG containing 2 mg/ml cytochrome c - AbU antibody unit - BU biological unit PBS, phosphate buffered saline - HKPBS high K⁺ PBS Special Issue dedicated to Dr. E. M. Shooter and Dr. S. Varon.     

The effect of phloretin on single potassium channels in myelinated nerve

The effect of phloretin, a dipolar organic compound, on single potassium channel currents of myelinateed nerve fibres of Xenopus laevis has been investigated, using inside-out patches prepared by the method of Jonas et al. (1989). The I channel, a potential dependent K channel with intermediate deactivation kinetics, was reversibly blocked by 20 µM phloretin applied on the inside; the block was strongest at negative membrane potentials and less pronounced at positive potentials. Phloretin shifted the curve relating open probability to membrane potential towards more positive potentials and reduced its slope and maximum. This confirms previous findings on the effect of phloretin on the voltage dependence of the fast macroscopic K conductance. Single channel conductance and deactivation kinetics were not altered by phloretin. Offprint requests to: Correspondence to: H. Meves     

Stability of periodic travelling wave solutions of a nerve conduction equation

Summary Nagumo's nerve conduction equation has travelling wave solutions of pulse type and periodic wave type. We consider the stability of the latter ones. We denote byL(c) the minimum spatial period of a periodic travelling wave solution whose propagation speed isc. It is shown that this travelling wave solution is unstable ifL′(c)<0.     

Forelimb muscle activity following nerve graft repair of ventral roots in the rat cervical spinal cord

Current research on the cellular mechanisms of nerve regeneration suggests the application of nerve growth factors at the repair sites to be beneficial. To test the effectiveness of this approach, we performed transections of the C6 and C7 ventral rootlets from their original sites in the spinal cord of 18 rats. We investigated the electrophysiological changes in three groups of rats operated on by different repair strategies. Six rats comprised the control group (G1). In the other 12 rats, 24 rootlets were implanted into the spinal cord by means of an intercostal nerve graft through the pia mater immediately after transection. Six rats (G2) had fibrin glue applied at the incision. The last 6 rats (G3) had grafts with acidic fibroblast growth factor (aFGF) added to the fibrin glue. The rats' functional recovery was evaluated electrophysiologically at 6 weeks and 6 months after the operation. Needle electromyography showed profound fibrillation potentials (Daube's scoring system) in the deltoid, biceps, and triceps of the operated forelimbs in all groups 6 weeks after the operation. After 6 months, there was a significant decrease in the amount of fibrillation potentials in all groups (G1, G2 and G3, p < 0.0001, 0.0001, 0.0009, respectively, generalized estimating equation, repeated measures) and a significantly high probability for motor units present in sampled muscles of G2 and G3 as compared to G1 (log odds ratio in G2 = 51.8316, G3 = 57.4262, generalized estimating equation). We conclude that several cervical roots can regenerate through intercostal nerve grafts applied using fibrin glue. Adding aFGF may increase the efficacy of sprouting.     

Wnt信号通路及相关神经因子对神经再生的影响

脑缺血可造成神经元损伤,影响神经功能。有关神经因子可诱导神经干细胞在一定条件下增殖分化成新的神经细胞,这些新的细胞在缺血性脑损伤后参与神经功能的修复。本文详细介绍了Wnt信号通路中相关蛋白的作用机制和Wnt信号通路对神经再生的影响,以及神经源性因子和促神经发生相关因子对于神经发生的影响。