Treatment of transected peripheral nerves with artemin improved motor neuron regeneration,but did not reduce nerve injury-induced pain behaviour

Incomplete recovery of function and neuropathic pain are common problems after peripheral nerve injury. To develop new treatment strategies for peripheral nerve injuries we investigated whether the neurotrophic factor artemin could improve outcome after sciatic nerve injuries in rats. Artemin is a member of the glial cell line-derived neurotrophic factor (GDNF) family and exerts neuroprotective effects on sensory neurons as well as influencing behavioural thermal sensitivity. We additionally evaluated if fibrin sealant, which is sometimes used as a nerve glue, had any effects on neuropathic pain-related behaviour. After the sciatic nerve had been transected, 30 animals were randomised to one of three groups: treatment with a fibrin sealant that contained artemin in conjunction with sutures; fibrin sealant with no artemin (sham) in conjunction with sutures; or sutures alone (n=10 in each group). Motor function, sensory function, and autotomy were evaluated from 1 to 12 weeks after injury. Retrograde flourogold tracing 12 weeks after injury showed that the addition of artemin increased the number of regenerating motor neurons. However, it did not improve their performance, as measured by the Sciatic Function Index, compared with sham or suture alone. Animals treated with artemin had a non-significant increase in motor nerve conduction velocity compared with sham. However, artemin did not reverse nerve injury-induced pain behaviour such as cold or heat hypersensitivity. Fibrin sealant in itself did not ameliorate motor performance, or regeneration of motor neurons, or give rise to nerve injury-induced pain behaviour. The results indicate that artemin is of value as a treatment for peripheral nerve injuries, although the effects were limited. As the artemin high-affinity receptor GFRα-3 is present in Schwann cells and not in motor neurons, the effect on motor neuron axon regeneration may result from an indirect effect through Schwann cells in the injured nerve.     

Ret和GDNF蛋白在先天性巨结肠中的表达

目的:探讨Ret和GDNF蛋白二者表达与先天性巨结肠(HD)的关系。方法:对我院2002年至2006年手术切除的经病理诊断为HD的标本52例进行免疫组化Ret和GDNF染色,显微镜下观察。结果:52例HD扩张段Ret和GDNF蛋白均阳性表达,狭窄段均为阴性表达。结论:HD的发生与Ret和GDNF蛋白缺失有关,活检中检测两种蛋白可以提高HD的诊断准确率,减少误诊发生。     

Marked dopaminergic cell loss subsequent to developmental, intranigral expression of glial cell line-derived neurotrophic factor

Glial cell line-derived neurotrophic factor (GDNF) shows potent neuroprotective as well as neurorestorative actions on the adult neurons impacted in animal models of Parkinson's disease (PD). Long-term pharmaco-physiological effects of GDNF on developing dopaminergic (DA) neurons have not yet been explored because of technical difficulties in producing prolonged cell type-specific delivery of this neurotrophic factor in mammalian embryonic brain. The current studies used our previously characterized 9.0-kb tyrosine hydroxylase promoter to produce transgenic mice with neuronal cell type-specific expression of GDNF in substantia nigra pars compacta (SNc) and locus coeruleus (LC). These mice were used to test the parsimonious hypothesis that increased developmental expression of GDNF in SNc and LC would significantly enhance the number of postmitotic adult neurons. To our surprise, adult transgenic mice carrying the TH9.0kb-GDNF hybrid gene showed dramatic reductions in both the numbers and the volumes of SNc-DA and LC-noradrenergic (NA) neurons by quantitative morphometric analysis. The decrease in the number of DA neurons was apparent as early as postnatal day 2, the period before the major naturally occurring apoptotic cell death in midbrain. Aged transgenic mice exhibited no further significant deficits in motor behaviors. These data suggest that continuous, early developmental GDNF expression exerts physiological effects on newly differentiated, immature dopamine neurons that differ from those observed on more mature and adult DA neurons. Further elucidation of the mechanisms underlying differential GDNF actions will greatly improve the pharmacological efficacy of GDNF in fetal neural transplantation as well as adult neuronal gene therapy in PD patients.     

脑溢安对脑出血大鼠脑内GDNF蛋白及mRNA表达的影响

目的观察脑出血模型大鼠脑内胶质细胞源性神经营养因子（GDNF）蛋白和mRNA的分布及中药脑溢安对其影响。方法通过微量注射器向苍白球注入Ⅶ型胶原酶0．4u建立脑出血模型。用免疫组织化学方法和原住杂交法分别观察脑出血后2h，6h，1d，4d，7d，14d共6个时间点GDNF蛋白及mRNA的表达变化，以阳性细胞计数作为观察指标。结果脑出血后2hGDNF蛋白主要表达于血肿周围的星型胶质细胞，6h表达开始增高，1d达高峰，以后逐渐降低，GDNF蛋白到第7天基本恢复到正常水平，14d后GDNF阳性细胞消失；在1d，4d两个时间点上，两组阳性细胞计数比较差异有显著性（P〈0．05）；而GDNF mRNA主要表达于神经元，1d后达高峰，7d后两者的表达水平继续下降但仍高于正常，14d后降至基础水平，在6h，1d，4d三个时间点上，两组阳性细胞计数比较差异有显著性（P〈0．01）。结论脑溢安可促进脑出血后GDNF蛋白及mRNA的表达。     

Recombinant adeno-associated virus vector expressing glial cell line-derived neurotrophic factor reduces ischemia-induced damage

To explore the potential of using the recombinant adeno-associated viral (rAAV) vector, expressing glial cell line-derived neurotrophic factor (GDNF) as the gene therapy for stroke, we injected rAAV vectors expressing GDNF (rAAV-GDNF) into the cortex of rats which had been experiencing transient bilateral common carotid artery ligation and right middle cerebral artery ligation for 90 min. GDNF levels in cortical tissues of rAAV-GDNF-injected animals were significantly higher than in the control animals injected with rAAV-expressing lacZ (rAAV-lacZ), indicating that rAAV can deliver and express the GDNF gene in cortical tissues. Triphenyltetrazolium chloride tissue stain analysis revealed that the rAAV-delivered GDNF gene could rescue the brain tissues from ischemia-induced injury. Cortical tissues which received rAAV-GDNF injections had both significantly smaller total volumes of infarction and smaller areas of infarction on each brain slice than those which were injected with rAAV-lacZ. An in situ labeling analysis demonstrated significantly less apoptotic cells in cortical tissues rescued by rAAV-GDNF, indicating prevention of apoptosis as the mechanism of cortical cell protection. Moreover, immunohistochemistry staining of Neu-N indicated that the rescued brain tissues contained the same number of Neu-N-positive neuronal cells as contralateral undamaged brain tissues. This provides strong evidence that cortical neuronal cells can be rescued by GDNF gene therapy. Indeed, these findings show that the rAAV is a potential delivery vector of GDNF gene for the therapy of stroke.     

维甲酸和联合应用神经营养因子对新生大鼠神经干细胞分化的影响

目的研究全反式维甲酸（ATRA）及联合应用神经营养因子（BDNF，GDNF）对体外培养的神经干细胞（NSCs）分化的影响。方法取新生SD大鼠的前脑室下带（SVZ）区，按NSCs的常规培养方法分离、培养。用免疫细胞化学法鉴定巢蛋白（nestin）、微管相关蛋白-2（MAP-2）、胶质原纤维酸性蛋白（GFAP）的表达，以此来观察ATRA、BDNF、GDNF单独或联合应用对次代神经球细胞分化的作用。结果原代及次代神经球均显示nestin阳性，并可分化为MAP-2阳性神经元样细胞及GFAP阳性胶质细胞样细胞。1μmol／LATRA可促进NSCs分化为MAP-2阳性细胞的比例达（29．14±5．00）％，显著高于对照组的（7．19±1．21）％，差异有高度统计学意义（P〈0．001）。ATRA联合应用10ng／ml的BDNF或GDNF，与单独使用ATRA比较，并不显著提高NSCs分化为MAP-2阳性细胞的比例。结论ATRA可促进神经干细胞向神经元方向分化，ATRA联合应用BDNF或GDNF无明显的协同作用。     

微囊化牛视网膜色素上皮细胞体外BDNF及GDNF分泌特性的研究

目的检测体外培养的牛视网膜色素上皮细胞（retinal pigment epithelium，RPE）脑源性神经营养因子（brain derived neurotrophic factor，BDNF）及胶质源性神经营养因子（glial cell line-derived neurotrophic factor，GDNF）分泌特点，并观察微囊包裹对细胞存活率及BDNF和GDNF分泌的影响。方法原代培养牛RPE，用高压静电成囊装置制备海藻酸钠-多聚赖氨酸-海藻酸钠微囊化细胞，台盼兰染色法检测囊内细胞活性，ELISA法检测BDNF及GDNF分泌量。结果原代及传代后RPE上清液中在基础状态下就能够检测到BDNF和GDNF，传代后两者的分泌量较原代无显著差异。微囊化细胞BDNF和GDNF分泌量在1-5 d与未微囊化细胞相比显著降低（P〈0.01），而6-8 d两组无显著差异。囊内活细胞数及BDNF和GDNF分泌量在体外培养的第14天至第21天趋于稳定。结论RPE基础状态下就能够分泌少量BDNF和GDNF，且不受传代及微囊包裹的影响。体外培养21 d后仍检测到囊内细胞的存活及BDNF和GDNF的分泌。牛RPE是一种具有一定前景的帕金森病细胞移植的供体。     

人GDNF基因的克隆

目的：克隆可表达人胶质细胞源性神经营养因子的基因。方法：从脑胶质细胞瘤患者术后的脑瘤组织中提取总ＲＮＡ，以ＲＴＰＣＲ方法扩增出了一段约５５８ｂｐ的ｃＤＮＡ片段，将这一片段克隆于ｐＵＣ１８载体中，进行全序列分析。结果：证实该研究所克隆的ｃＤＮＡ是编码正确的人ＧＤＮＦ基因。与发表于ＧｅｎｅＢａｎｋ上的序列相比，发现该研究克隆的基因有一段７８ｂｐ的核苷酸序列缺失，但不影响密码子的阅读框。结论：克隆到了编码正确的人ＧＤＮＦ的ｃＤＮＡ全序列，对帕金森病基因治疗的基础研究及临床应用具有重要意义。     

GDNF cDNA在神经及非神经细胞系中的表达

目的：研究重组GDNFcDNA在神经及非神经细胞系中的表达。方法：重组克隆，基因转染及RT－PCR。结果：CV1及SH－SY-5Y细胞中无GDNF内源性表达，转基因后出现GDNF表达条带。NG108－15细胞有GDNF的内源性表达，转基因后表达条带增强。结论：重组GDNFcDNA在神经及非神经细胞系中均有较强表达，提示以此制备的工程细胞在Parkinson’s病基因治疗中可能具有重要作用。     

Development of pontine noradrenergic A5 neurons requires brain-derived neurotrophic factor

Pontine noradrenergic A5 neurons play a pivotal role in maturation and regulation of the brainstem respiratory rhythm-generating network. Analysis of newborn brain-derived neurotrophic factor (BDNF)-null mice revealed a marked loss of tyrosine hydroxylase-positive A5 neurons compared to wildtype controls that was rescued by null mutation of the proapoptotic gene Bax. In cultures of the A5 region from E12.5 rat embryos, BDNF significantly increased the number and branching of tyrosine hydroxylase-positive neurons. Immunoneutralization of endogenous glial cell line-derived neurotrophic factor partially inhibited the BDNF-dependent increase in the number of tyrosine hydroxylase-positive cells without affecting neurite number. The A5 nucleus is the first brainstem cell group identified at which BDNF is required in vivo for development of neurons critical for cardiorespiratory control.