Expression pattern of Nogo‐A,MAG, and NgR in regenerating urodele spinal cord

Background: The mammalian central nervous system is incapable of substantial axon regeneration after injury partially due to the presence of myelin‐associated inhibitory molecules including Nogo‐A and myelin associated glycoprotein (MAG). In contrast, axolotl salamanders are capable of considerable axon regrowth during spinal cord regeneration. Results: Here, we show that Nogo‐A and MAG, and their receptor, Nogo receptor (NgR), are present in the axolotl genome and are broadly expressed in the central nervous system (CNS) during development, adulthood, and importantly, during regeneration. Furthermore, we show that Nogo‐A and NgR are co‐expressed in Sox2 positive neural progenitor cells. Conclusions: These expression patterns suggest myelin‐associated proteins are permissive for neural development and regeneration in axolotls. Developmental Dynamics 242:847–860, 2013. © 2013 Wiley Periodicals, Inc.     

定量检测神经生长抑制因子及受体在脑梗死大鼠脑组织中的表达

目的观察神经生长抑制因子(Nogo-A)及其受体(NgR)在脑梗死大鼠不同时间点表达的变化规律。方法将80只SD大鼠制成易脑卒中型肾血管性高血压大鼠模型后,随机分为脑梗死组和对照组(各40只),脑梗死组大鼠施行右侧大脑中动脉闭塞术,用免疫组织化学法和荧光定量RT-PCR法检测术后第1、2、4和8周脑梗死灶周围Nogo-A及NgR mRNA表达的变化规律。结果免疫组织化学显示脑梗死组Nogo-A和NgR含量在病灶周围先呈逐渐上升趋势,第4周达到高峰,较对照组显著升高(P<0.05),Nogo-A在第8周降低,与对照组无显著性差异(P>0.05);而NgR略微下降,但仍高于对照组(P<0.01)。荧光定量RT-PCR显示脑梗死组Nogo-A与NgRmRNA表达均先上升,在第4周达到高峰,与对照组差异有显著性意义(P<0.01),第8周Nogo-A mRNA表达下降仍高于对照组(P<0.01);NgR mRNA表达在第8周时与对照组无显著性差异(P>0.05)。结论脑梗死损伤可使梗死灶周围组织中Nogo-A及NgR表达增加,可能与脑梗死后神经再生障碍有关。     

三维球体间充质干细胞移植对大鼠缺血再灌注损伤脑组织Nogo-A及NgR表达的影响

目的 探讨胎盘来源间充质干细胞移植对脑缺血再灌注后大鼠脑组织Nogo—A及其受体NgR的mRNA及蛋白表达的影响及意义。方法 实验动物随机分为假手术组(Sham组)及模型组,模型组再分为治疗组(MSCs组)以及溶剂对照组(Vehicle组),应用线栓法制备大鼠大脑中动脉缺血模型,缺血2h后拔除鱼线再灌注,1d后MSCs组注射间充质干细胞,Vehicle组注射等量培养基溶液,移植后1d,3d,7d应用RT-PCR法检测mRNA表达水平;Western blot法检测蛋白表达水平。结果 与Vehicle组相比,MSCs组大鼠7d神经运动功能有明显改善(P<0.05);MSCs组1,3,7dmRNA及蛋白水平均较Vehicle组降低(P<0.05)。结论 胎盘间充质干细胞移植可以改善脑缺血再灌注后神经运动功能,其机制可能与下调脑组织Nogo—A及其受体NgR水平有关。     

Nogo receptor antagonizes p75NTR-dependent motor neuron death

The Nogo-66 receptor (NgR) plays a critical role in restricting axon regeneration in the central nervous system. This inhibitory action is in part mediated by a neuronal receptor complex containing p75NTR, a multifunctional receptor also well known to trigger cell death upon binding to neurotrophins such as NGF. In the present study, we show that Pep4 and NEP1-40, which are two peptides derived from the Nogo-66 sequence that modulate NgR-mediated neurite outgrowth inhibition, prevent NGF-stimulated p75NTR-dependent death of cultured embryonic motor neurons. They also confer protection on spinal cord motor neurons after neonatal sciatic nerve axotomy. These findings demonstrate an as-yet-unknown function of NgR in maintaining neuronal survival that may be relevant for motor neuron development and degeneration.     

电针对脊髓损伤大鼠 Nogo/NgR 信号通路相关因子基因表达的影响

目的观察电针对脊髓损伤大鼠Nogo/NgR信号通路相关因子基因表达变化,探讨电针治疗脊髓损伤的可能作用机制。方法大鼠随机分为模型组、电针组、阻断剂组、电针+阻断剂组、假手术组,用改良Allen’s撞击法制备T10脊髓损伤模型,分别于治疗后1、7、14 d对各组大鼠进行BBB功能评分;在7、14 d于损伤处提取脊髓组织,以蛋白印迹法(Western blot)测定各组大鼠脊髓组织中Nogo-A、NgR、LINGO-1蛋白的表达变化,实时荧光定量PCR测定Nogo-A、NgR、LINGO-1 mRNA的表达变化。结果脊髓损伤后,造模大鼠1 d后BBB评分均为0分;治疗7、14 d后,各治疗组BBB评分均明显高于模型组(P0.05),且电针+阻断剂组优于电针组、阻断剂组(P0.05)。与假手术组比较,同时间点模型组各基因表达均明显提高(P0.05);与模型组比较,各治疗组基因表达明显下降(P0.05);电针+阻断剂阻组与电针组比较,同时间点LINGO-1基因表达有显著差异(P0.05)。结论 Nogo/NgR信号通路在脊髓损伤后神经的再生与修复过程中起着关键作用,电针通过抑制Nogo/NgR信号通路而对脊髓损伤大鼠起治疗作用。     

Nogo—A及NgR在墨西哥钝口螈脑组织中的表达及意义

目的探讨勿动蛋白A（Nogo．A）及勿动蛋白受体（NgR）在正常墨西哥钝VI螈及其中脑胆碱能神经元损伤后脑组织中的表达。方法以正常墨西哥钝口螈脑组织和中脑胆碱能神经元损伤后第3、7、14、21天脑组织作为研究对象,采用免疫荧光技术观察正常墨西哥钝口螈脑组织中Nogo—A及NgR的表达;分别用荧光定量PCR和蛋白质印迹法（WB法）检测正常墨西哥钝口螈和损伤组脑组织中Nogo—A及NgR的mRNA含量和蛋白含量的变化。结果正常墨西哥钝口螈脑组织中存在Nogo．A及NgR的表达,在墨西哥钝口螈中脑胆碱能神经元损伤后（注入AF64A）第3天,中脑乙酰胆碱转移酶（CHAT）阳性细胞数明显减少,与正常组比较差异有统计学意义（P〈0．01）,损伤后第7、14、21天均有ChAT、5-溴脱氧尿嘧啶核苷（BrdU）双阳性细胞,且随时间的延长而增加。中脑胆碱能神经元损伤后第3、7、14、21天脑组织中,Nogo．A的mRNA和蛋白水平的表达量与正常组比较差异均无统计学意义;而NgR的mRNA和蛋白水平的表达量均下降,与正常组比较差异有统计学意义（P〈0．05）。结论中枢神经系统损伤后的再生可能与NgR表达量的下降有关。     

Nogo基因及其受体与缺氧缺血性脑白质损伤的研究

早产儿脑损伤问题是围产期医学的热点问题。早产儿脑损伤多表现为脑白质的损伤,白质损伤也可累及皮质。早产儿脑白质损伤与少突胶质细胞的缺氧缺血易损性有关。研究发现3种中枢神经髓鞘来源的主要髓磷脂相关轴突生长抑制物:髓磷脂相关抑制物(Nogo-A,myelin-associated inhibitors Nogo)、髓鞘相关糖蛋白(myelin-associated glycoprotein,MAG)、少突胶质细胞髓鞘糖蛋白(oligodendrocyte-myelin glycoprotein,OMgp)。Nogo-A、MAG和OMgp可能通过与神经元上的一个共同受体Nogo-66受体(NgR)结合并传导信号级联反应,抑制神经元轴突的生长。通过RNA干扰下调NgR的表达,理论上可以同时减轻这3个髓磷脂相关抑制因子的作用,在缺氧缺血脑损伤后减少神经元的凋亡,促进神经轴突再生,具有很好的应用前景。     

慢性脑缺血大鼠Nogo-A和NgR表达的变化

目的 探讨大鼠海马区Nogo-A和NgR表达在慢性脑缺血的不同时间点的动态变化.方法 大鼠随机分为假手术组、15、30和60 d模型组;采用双侧颈总动脉永久结扎建立慢性脑缺血模型;Morris水迷宫试验检测行为学变化;免疫组化染色检测Nogo-A和NgR的表达变化.结果 Nogo-A和NgR免疫反应阳性细胞数模型组比假手术组均增多(P＜0.01),与行为学改善基本相符.结论 慢性脑缺血造成Nogo-A和NgR表达持续升高可能是成年哺乳动物损伤后神经再生障碍的重要原因之一.     

Nogo-A及其受体NgR的研究进展

中枢神经系统的神经元是一群高度分化的细胞,其损伤后修复与再生是非常困难和复杂的。Nogo是最近研究发现的在中枢神经系统损伤后具有再生抑制作用的因子。Nogo基因的表达产物有3种:Nogo-A、Nogo-B、Nogo-C,其中,Nogo-A的抑制作用越来越受到研究者的重视,成为当前神经再生研究领域的热点。现就Nogo-A及其受体的结构、分布、作用机制及有关最新研究进展做一简单综述。     

Spatiotemporal expression of Nogo-66 receptor after focal cerebral ischemia

NgR, the receptor for the neurite outgrowth inhibitor Nogo-66, plays a critical role in the plasticity and regeneration of the nervous system after injury such as ischemic stroke. In the present study, we used immunohistochemistry to investigate the regional expression of NgR in rat brain following middle cerebral artery occlusion (MCAO). NgR protein expression was not observed in the center of the lesion, but was elevated in the marginal zone compared with control and sham-operated rats. The cerebral cortex and hippocampus (CA1, CA2, and CA3) showed the greatest expression of NgR. Furthermore, NgR expression was higher in the ipsilesional hemisphere than on the control side in the same coronal section. Although time-dependent changes in NgR expression across brain regions had their own characteristics, the overall trend complied with the following rules: NgR expression changes with time showed two peaks and one trough; the ifrst peak in expression appeared between 1 and 3 days after MCAO; expression declined at 5 days; and the second peak occurred at 28 days.