Guidance of acetylcholinesterase-containing fibres by target tissue in co-cultured brain slices

Slices of various brain regions were prepared from newborn and from 7-day old rats and co-cultured in different combinations. In the majority of co-cultures of septal and hippocampal slices, acetylcholinesterase-positive fibres originating in the septal nuclei invaded the adjacent hippocampal slice. A similar pattern of hippocampal ingrowth by acetylcholinesterase-positive fibres occurred with slices prepared from the nucleus basalis of Meynert and from spinal cord. Septal neurones also projected to cortical slices, an effect which even occurred in the presence of their natural target tissue. In contrast to these massive projections to brain areas which in situ receive cholinergic inputs, no significant acetylcholinesterase-positive fibre ingrowth was observed in tissues which lack major cholinergic afferents in situ (hypothalamus, substantia nigra and cerebellum). These results indicate that under our culture conditions, acetylcholinesterase-positive fibres selectively invade cholinergic target areas. This effect is independent of the brain area from which the cholinergic neurones were derived.     

NGF对哮喘小鼠气道阻力和肺组织Akt/PKB表达的影响

目的探讨NGF介导的Akt/PKB信号转导通路在哮喘小鼠发病中的作用。方法BALB/c小鼠30只,按随机数字表法随机分为正常对照组、哮喘组、NGF阻断组。利用An iRes2005肺功能仪测小鼠气道阻力,运用免疫组织化学方法测定Akt/PKB的组织表达,M etamoph图像分析系统对结果进行分析。结果哮喘小鼠吸气阻力和呼气阻力明显高于正常组小鼠(P<0.01),NGF阻断组小鼠吸气阻力和呼气阻力明显低于哮喘组。免疫组织化学染色结果显示哮喘组Akt/PKB在肺组织炎性细胞的表达及AK t/PKB阳性炎症细胞数明显多于正常对照组(P<0.05),而NGF阻断组则明显低于哮喘组(P<0.05)。结论NGF介导哮喘气道高反应和炎症反应,Akt/PKB参与了哮喘发病中NGF介导的信号传导。     

Some studies on the mechanism of action of antibodies to nerve growth factor.

The effects of antibodies to the nerve growth factor from mouse salivary gland were examined in vitro and in vivo. Treatment of explants of receptive ganglia with antibody and complement did not produce cell damage as judged by the ability of the tissue to respond to nerve growth factor. New-born mice experimentally depleted of or genetically deficient in key complement components were susceptible to the action of the antiserum.These results show that the effect of the antibody is independent of complement and are consistent with the view that it acts by neutralization of endogenous nerve growth factor.     

Molecular basis of congenital insensitivity to pain with anhidrosis (CIPA): Mutations and polymorphisms in TRKA (NTRK1) gene encoding the receptor tyrosine kinase for nerve growth factor

Congenital insensitivity to pain with anhidrosis (CIPA), also referred to as hereditary sensory and autonomic neuropathy type IV (HSAN‐IV), is an autosomal recessive hereditary disorder characterized by recurrent episodic fever, anhidrosis (inability to sweat), absence of reaction to noxious stimuli, self‐mutilating behavior, and mental retardation. The TRKA (NTRK1) gene located on chromosome 1 (1q21‐q22), consists of 17 exons and spans at least 23 kb. TRKA encodes the receptor tyrosine kinase (RTK) for nerve growth factor (NGF) and is the gene responsible for CIPA. Defects in NGF signal transduction at the TRKA receptor lead to failure to support survival of sympathetic ganglion neurons and nociceptive sensory neurons derived from the neural crest. Thirty‐seven different TRKA mutations, identified in patients in various countries, including nine frameshift, seven nonsense, seven splice, and 14 missense mutations, are distributed in an extracellular domain involved in NGF binding, as well as in the intracellular signal‐transduction domain. Extensive analysis of CIPA mutations and associated intragenic polymorphisms should facilitate detection of CIPA mutations and aid in the diagnosis and genetic counseling of this painless but severe genetic disorder with devastating complications. In addition, naturally occurring TRKA missense mutations with loss of function provide considerable insight into the structure–function relationship in the RTK family. Further, molecular pathology of CIPA would provide unique opportunities to explore critical roles of the autonomic sympathetic nervous system as well as peripheral sensory nervous system that transmit noxious stimuli in humans. Hum Mutat 18:462–471, 2001. © 2001 Wiley‐Liss, Inc.     

大鼠脊髓损伤后NGF及其受体TrkA在运动神经元及神经胶质细胞表达的变化

为探讨脊髓损伤后运动神经元及神经胶质细胞内神经生长因子(NGF)及其高亲和力受体(TrkA)表达的变化,用改良Allen重击法损伤SCI组动物T12脊髓,按伤后存活时间再将动物分为脊髓损1 d组、2 d组和5 d组。各组动物的脊髓切片经ABC法免疫组织化学染色,用光镜观察TrkA及NGF在脊髓前角运动神经元表达的变化和胶质纤维酸性蛋白(GFAP)及NGF免疫反应阳性胶质细胞的反应性增生程度,并进行图像分析。结果显示:脊髓损伤后前角运动神经元TrkA及NGF的表达随脊髓损伤后动物存活时间的延长逐渐上调;脊髓白质和灰质内尤其是皮质脊髓束内GFAP及NGF阳性胶质细胞明显增生;与此同时,室管膜细胞内亦可见明显的NGF免疫反应产物。上述结果表明,脊髓损伤可刺激脊髓前角运动神经元表达TrkA及NGF,通过自分泌维持受损神经元的存活;损伤部位反应性增生的胶质细胞亦可产生NGF,通过旁分泌作用于脊髓前角运动神经元或皮质脊髓束的轴突末梢,以维持运动神经元的存活及促进皮质脊髓束的再生;适时补充外源性神经营养素或改变损伤局部的微环境将有利于受损脊髓的修复和再生。     

Substance P and somatostatin metabolism in sympathetic and special sensory ganglia in vitro

Mechanisms regulating the content of the putative peptide transmitters, substance P and somatostatin, were examined in several neuronal populations in culture. Substance P levels increased more than 25-fold within 48 h in sympathetic neurons in the explanted rat superior cervical ganglion, and remained elevated for 4 weeks. Identity of the peptide was authenticated by combined high pressure liquid chromatography-radioimmunoassay. Veratridine prevented the increase of substance P in vitro, and tetrodotoxin blocked the veratridine effect, suggesting that sodium ion influx and membrane depolarization prevent peptide elevation. Veratridine (or potassium)-induced membrane depolarization released substance P into the culture medium through a calcium-dependent process. Consequently, at least some veratridine effects are attributable to release and subsequent depletion of ganglion peptide. However, the inhibitory effects of veratridine were far greater than could be accounted for by the quantity of peptide released, suggesting a separate influence on net synthesis (synthesis less catabolism) of substance P. Viewed in conjunction with previous in vivo studies, our observations suggest that trans-synaptic impulses, through the mediation of postsynaptic sodium flux, release substance P from sympathetic neurons and also regulate intracellular peptide metabolism. To determine whether the processes regulating substance P in sympathetic neurons reflect generalized mechanisms, a different peptide, somatostatin, was examined in sympathetic neurons; moreover, substance P was examined in a different neuronal population, special sensory neurons in the nodose ganglion. Substance P levels increased significantly in both sympathetic and sensory neurons after explantation, and somatostatin levels increased in sympathetic neurons. In each instance, the increase was dependent upon the presence of the calcium ions. Moreover, these increases were all prevented by veratridine, in a tetrodotoxin-sensitive manner. Our observations suggest that common regulatory mechanisms govern peptide transmitter metabolism in diverse neuronal populations.     

神经生长因子对穹窿海马伞切割后海马自体神经干细胞增殖和向神经元分化的影响

目的 探讨切割穹窿海马伞及脑室给予神经生长因子(NGF)后,对大鼠海马自体神经干细胞增殖和分化为神经元的影响.方法 12只SD大鼠,随机分成给药组和对照组,每组6只,切割右侧穹窿海马伞,两组切割后即时及第2d、4d向侧脑室分别注射NGF和人工脑脊液, 并在术后第3～7d每日腹腔注射2次BrdU.于术后28d灌注取脑、冷冻切片,行BrdU/NF-200免疫荧光双标检测.结果 海马齿状回内BrdU阳性细胞数,给药组和对照组切割侧明显多于正常侧,给药组切割侧和正常侧分别多于对照组切割侧和正常侧;海马齿状回内的BrdU/NF-200双标神经元数,给药组切割侧最多,给药组正常侧和对照组切割侧较少,而对照组正常侧则无.结论 切割穹窿海马伞后,可致大鼠海马齿状回自体神经干细胞增殖加快并向神经元分化,脑室施加 NGF可促进其增殖和分化.     

Caudal end of the rat spinal dorsal horn

We have previously demonstrated that the transformation of the caudal spinal cord through the conus medullaris to the filum terminale takes place in three steps. In the conus medullaris the twin layers of CGRP-immunoreactive and IB4-labeled primary afferent fibers as well as the translucent portion of the superficial dorsal horn equivalent to the substantia gelatinosa discontinue before the complete removal of the dorsal horn. Parallel with these changes VGLUT1-immunoreactive myelinated primary afferent fibers arborize not only in the deep layers but also in the entire extension of the remaining dorsal horn, while scattered CGRP fibers still remains at the margin of and deep in the dorsal horn. PKCgamma-immunoreactive dorsal horn neurons discontinue parallel with the disappearance of the IB4-labeled nerve fibers. These observations suggest that in the dorsal horn certain neurons are linked to the substantia gelatinosa, while others are substantia gelatinosa-independent neurons.     

NGF对局灶性脑缺血再灌注大鼠海马CREB表达的上调作用

目的探讨外源性神经生长因子(NGF)对局灶性脑缺血再灌注大鼠海马CREB和磷酸化的CREB(p-CREB)表达的影响。方法用线栓法阻塞大鼠大脑中动脉制作局灶性脑缺血再灌注模型,应用免疫组织化学、W estern B loting和图像分析方法检测大鼠海马CA1区CREB和磷酸化CREB表达。结果假手术组海马CA1区CREB有明显表达,缺血再灌注组CA1区表达较假手术组减少,NGF组CA1区的CREB表达多于缺血再灌注组(P<0.05)。假手术组海马CA1区p-CREB表达很少,缺血再灌注组p-CREB表达多于假手术组,NGF组p-CREB表达多于缺血再灌注组(P<0.05)。结论NGF上调海马CREB和p-CREB的表达,对缺血神经元起保护作用,CREB和p-CREB参与NGF对缺血神经元的保护作用机制。