Expression patterns of erythropoietin and its receptor in the developing spinal cord and dorsal root ganglia

Recombinant human erythropoietin (EPO) is neuroprotective in animal models of adult spinal cord injury, and reduces apoptosis in adult dorsal root ganglia after spinal nerve crush. The present work demonstrates that spinal cord and dorsal root ganglia share dynamic expression patterns of EPO and its receptor (EPOR) during development. C57Bl mice from embryonic days (E) 8 (E8) to E19 were studied. In spinal cord and dorsal root ganglia, EPOR expression in all precursor cells preceded the expression of EPO in subsets of neurons. On E11, EPO-immunoreactive spinal motoneurons and ganglionic sensory neurons resided adjacent to EPOR-expressing radial glial cells and satellite cells, respectively. From E12 onwards, EPOR-immunoreactivity decreased in radial glial cells and, transiently, in satellite cells. Simultaneously, large-scale apoptosis of motoneurons and sensory neurons started, and subsets of neurons were labelled by antibodies against EPOR. Viable neurons expressed EPO and EPOR. Up to E12.5, apoptotic cells were EPOR-immunopositive, but variably EPO-immunonegative or EPO-immunopositive. Thereafter, EPO-immunonegative and EPOR-immunopositive apoptotic cells predominated. Our findings suggest that EPO-mediated neuron-glial and, later, neuron–neuronal interactions promote the differentiation and/or the survival of subsets of neurons and glial cells in central as well as in peripheral parts of the embryonic nervous system. Correspondingly, expression of phospho-Akt-1/protein-kinase B extensively overlapped expression sites of EPO and EPOR, but was absent from apoptotic cells. Identified other sites of EPO and/or EPOR expression include radial glial cells that transform to astrocytes, cells of the floor plate and notochord as well as neural crest-derived boundary cap cells at motor exit points and cells of the primary sympathetic chain.     

The immunocytochemical distribution of seven peptides in the spinal cord and dorsal root ganglia of horse and pig

Summary The distribution of calcitonin gene-related peptide (CGRP), enkephalin, galanin, neuropeptide Y (NPY), somatostatin, tachykinins and vasoactive intestinal polypeptide (VIP) was compared in cervical, thoracic, lumbar and sacral segmental levels of spinal cord and dorsal root ganglia of horse and pig.In both species, immunoreactivity for the peptides under study was observed at all segmental levels of the spinal cord. Peptide-immunoreactive fibres were generally concentrated in laminae I–III, the region around the central canal, and in the autonomic nuclei. A general increase in the number of immunoreactive nerve fibres was noted in the lumbosacral segments of the spinal cord, which was particularly exaggerated in the case of VIP immunoreactivity. In the horse, some CGRP-, somatostatin- or tachykinin-immunoreactive cell bodies were present in the dorsal horn. In the pig, cells immunoreactive for somatostatin, enkephalin or NPY were noted in a similar location.In the ventral horn most motoneurones were CGRP-immunoreactive in both species. However, in pig many other cell types were CGRP-immunoreactive not only in the ventral horn, but also in laminae V–VI of the dorsal horn.With the exception of enkephalin and NPY immunoreactivity, which was not seen in pig dorsal root ganglia, all peptides studied were localised to neuronal cell bodies and/or fibres in the dorsal root ganglia. In both species, immunolabelled cell bodies were observed in ganglia from cervical, thoracic, lumbar and sacral levels, with the exception of VIP-immunoreactive cells that were detected only in the lumbosacral ganglia. Numerous CGRP- and tachykinin-immunoreactive cell bodies were visualised in both species, while the cells immunolabelled with other peptide antisera were much lower in number.In both species, immunostaining of serial sections revealed that a subset of CGRP-immunoreactive cells co-expressed tachykinin, galanin or somatostatin immunoreactivity. In the horse some enkephalin-immunoreactive cells were also CGRP positive and occasionally combinations of three peptides, e.g. CGRP, tachykinin and galanin or CGRP, tachykinin and enkephalin were identified.The results obtained suggest that the overall pattern of distribution of peptide immunoreactivities is in general agreement with that so far described in other mammals, although some species variations have been observed, particularly regarding the presence of immunoreactive cell bodies in the dorsal horn of the spinal cord.     

大鼠桡神经钳夹伤后背根节和脊髓nNOS免疫阳性神经元的变化

目的研究大鼠桡神经钳夹伤后背根神经节(DRG)和脊髓nNOS免疫阳性神经元的变化,探讨NO是否参与大鼠桡神经钳夹伤后的DRG和脊髓水平的痛觉调制。方法用辣根过氧化物酶追踪大鼠桡神经的由来;大鼠桡神经钳夹伤结合免疫组化法,研究桡神经钳夹伤后DRG鄄和脊髓的nNOS免疫阳性结构变化。结果(1)大鼠桡神经的组成范围在C5～T1;(2)大鼠桡神经钳夹伤后,DRG内nNOS免疫阳性神经元的变化难以分析:脊髓后角nNOS免疫阳性结构数量减少、免疫强度下降。结论大鼠桡神经钳夹伤后,脊髓nNOS免疫阳性结构发生可塑性变化,NO在桡神经钳夹伤后的痛觉调制中有一定的作用。     

Regulatory expression of Neurensin-1 in the spinal motor neurons after mouse sciatic nerve injury

Axonal regeneration after crush injury of the sciatic nerve has been intensely studied for the elucidation of molecular and cellular mechanisms. Neurite extension factor1 (Nrsn1) is a unique membranous protein that has a microtubule-binding domain and is specifically expressed in neurons. Our studies have shown that Nrsn1 is localized particularly in actively extending neurites, thus playing a role in membrane transport to the growing distal ends of extending neurites. To elucidate the possible role of Nrsn1 during peripheral axonal regeneration, we examined the expression of Nrsn1 mRNA by in situ hybridization and Nrsn1 localization by immunocytochemistry, using a mouse model. The results revealed that during the early phase of axonal regeneration of motor nerves, Nrsn1 mRNA is upregulated in the injured motor neuron. Nrsn1 is localized in the cell bodies of motor neurons and at the growing distal ends of regenerating axons. These results indicate that Nrsn1 plays an active role in axonal regeneration as well as in embryonic development.     

Microvascularization of the human central and peripheral nervous system: A new microcomputed tomography method

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The effects of gallamine on field and dorsal root potentials produced by antidromic stimulation of motor fibres in the frog spinal cord

Summary The effects of gallamine on the intraspinal field potentials and the dorsal root potentials produced by antidromic stimulation of motor fibres were studied in the isolated frog spinal cord preparation. After gallamine (10^-3 M), the duration of the negative field potential produced by antidromic activation of motoneurons (N₁ response) was increased often without changing its amplitude. This resulted in an increased passive spread of the antidromic action potential towards the dorsal dendritic regions, where afferent fibres terminate.In the untreated spinal cord, stimulation of motor axons produced a late negative dorsal root potential (VR-DRP) which was depressed after gallamine administration. Abolition of the VR-DRP was frequently associated with the appearance of a short latency, conducted response, in the dorsal roots (EVR-DRP). The earliest component of the EVR-DRP had a latency ranging between 0.5 and 2.5 ms measured after the peak of the N₁ response recorded at the motor nucleus. Such a brief latency of the EVR-DRP suggests that this response results from electrical interaction between motoneurons and afferent fibres. After gallamine, the primary afferent depolarization produced by orthodromic stimulation of sensory nerves facilitates the EVR-DRP without necessarily increasing the amplitude or duration of the N₁ response. Also, gallamine appears to increase directly the excitability of the afferent fibre terminal arborizations.The nature of the electrical interaction between motoneuron dendrites and afferent fibre terminal arborizations is discussed in terms of two hypotheses: interaction by current flows and by electrical coupling.     

坐骨神经火器性断裂伤后腰脊髓及脊神经节内微循环损伤特点

目的 :研究坐骨神经火器性断裂伤后脊髓和脊神经节内微循环的变化特点。方法 :通过 5 3式滑膛枪建立兔坐骨神经火器性断裂伤模型 ,在伤后第 1、3、7、15、3 0天取材。采用伊文思兰 (Evan’sblue ,EB)示踪、光电镜观察、组织含水量测定等方法检测脊髓、脊神经节内微循环变化特点。结果 :坐骨神经火器性断裂伤后 ,脊髓及脊神经节内微循环受到破坏 ,表现为内皮细胞变性、坏死及脱落 ,对EB的通透性明显增高 ,组织含水量增高 ,3天达高峰 ,脊神经节损伤较脊髓严重 ;伤后 3 0天腰脊髓、脊神经节内微循环的通透性仍高于正常。结论 :脊神经节及脊髓内微循环受到破坏是坐骨神经火器性断裂伤的重要特征之一 ,脊神经节损伤较脊髓严重     

Radiologic anatomy of the spinal dorsal horn at the cervical level (anatomic-MRI correlations)

The spinal dorsal horn is known for its important functional role in the field of transmission and modulation of sensory afferents. Because of this, the dorsal horn represents a target for numerous analgesic and antispastic procedures. Thus, it would be interesting to develop imaging dedicated to this spinal structure. The purpose of this study was to investigate the radiologic anatomy of the cervical dorsal horn by magnetic resonance imaging (MRI) (1.5T). The first step consisted in the validation of the anatomic information provided by MRI on 5 human cadavers. A spin-echo sequence (T2, 2000/45) enabled the demonstration of good correlations between histologic sections and axial MRI slices performed at the corresponding cervical levels. The second step was the <相似文献   

Toxoplasmosis of the spinal cord in an immunocompromised patient: case report and review of the literature

We, herein, describe an HIV-positive patient with toxoplasmosis of the spinal cord. We also carried out a comprehensive literature review of this topic, with emphasis on the diagnostic tools and therapeutic approach.     

Effects of nociceptin and analogues of nociceptin upon spontaneous dorsal root activity recorded from an in vitro preparation of rat spinal cord

The 17 amino acid peptide nociceptin has been implicated in pain modulation in the central nervous system. The effects of bath applied nociceptin, and some analogues of nociceptin, upon spontaneous lumbar dorsal root activity have been investigated in an isolated preparation of rat spinal cord. Nociceptin was found to reversibly depress spontaneous dorsal root activity at concentrations of 1.0 μM and 10.0 μM (IC₅₀ 2.0 μM), whereas acetyl-nociceptin at concentrations up to 10 μM had no detectable effect. Omission of the last four amino acids (nociceptin 1–13), increased the potency of the effect upon dorsal root activity by approximately 100-fold (IC₅₀ 30 nM), but activity was lost when only the first seven amino acids of the nociceptin molecule (nociceptin 1–7) were tested.     

腺病毒介导的神经营养素-3基因能够在大鼠脊髓前角运动神经元内过表达神经营养素-3

目的观察腺病毒介导的神经营养素-3(NT-3)基因在发出坐骨神经传出纤维的大鼠脊髓前角运动神经元的过表达。方法在坐骨神经内直接注射含有绿色荧光蛋白(GFP)基因(报告基因)的NT-3基因重组腺病毒(Ad-NT-3-GFP),7d后应用免疫荧光组织化学染色技术,在荧光显微镜下观察脊髓前角运动神经元的NT-3过表达。结果 GFP表达组(对照组)和NT-3加GFP表达组两组动物的L4和L5脊髓段横切片上,有绿色荧光蛋白阳性标记的细胞。在NT-3加GFP表达组,还可以观察到NT-3阳性标记的细胞,这种细胞能与绿色荧光蛋白阳性标记的细胞重合,是过表达NT-3的前角运动神经元。与GFP表达组的前角运动神经元形态比较,NT-3加GFP表达组的过表达NT-3的前角运动神经元呈现更富有分支的突起。结论腺病毒介导的NT-3基因能够在发出坐骨神经传出纤维的大鼠脊髓前角运动神经元内过表达NT-3,这为下一歩应用NT-3基因治疗策略修复实验性脊髓损伤提供初歩的实验资料。     

Electrophysiological properties of sympathetic preganglionic neurons in the cat spinal cord in vitro

Intracellular recordings were obtained from sympathetic preganglionic neurons of the intermedio-lateral nucleus of the adult cat in slices of upper thoracic spinal cord maintained in vitro. The neurons were identified by their antidromic responses to stimulation of various ipsilateral sites. Sites from which antidromic responses could be evoked were the white ramus, the ventral root, the ventral root exit zone, the white matter between the latter and the outer edge of the tip of the ventral horn, the lateral edge of the ventral horn. Resting membrane potential was –61.3±1.6 mV (mean±SEM), input resistance 67.5±3.7 M, time constant 11.5±1.2 ms. The amplitude of the action potential generated by antidromic or direct stimulation was 77.4±2.3 mV. Threshold for direct spikes was 18.2±1.8 mV. The action potential had an average duration of 3.03±0.16 ms. It showed a prominent hump on the falling phase. The action potential had a tetrodotoxin (TTX)-sensitive and a TTX-resistant component. The latter was abolished by cobalt.Tetraethylammonium, cesium and barium prolonged the action potential duration which acquired a plateau-shape. A prolonged after-hyperpolarization (AHP) followed the sympathetic preganglionic neuron spike. Following a single spike, AHP duration and peak amplitude were 2.8±0.3 s and 16.6±0.7 mV, respectively. The AHP was abolished by cesium or barium, but enhanced by tetraethylammonium. An AHP followed the TTX-resistant spike. EPSPs and IPSPs could be generated by focal stimulation. The EPSP triggered spikes when threshold (15.0±2.0 mV) was reached. The slice of the thoracic spinal cord provides a useful experimental preparation for analysis of cellular properties and synaptic mechanisms of the sympathetic preganglionic neuron.     

An analysis of response properties of spinal cord dorsal horn neurones to nonnoxious and noxious stimuli in the spinal rat

Summary Electrophysiological properties of neurones in the spinal cord dorsal horn were studied in decerebrated, immobilized spinal rats. Extracellular recordings were performed at the thoraco-lumbar junction level. Each track was systematically located by extracellular injection of pontamine sky blue. According to their responses to mechanical peripheral stimuli, cells were classified in four classes: Class 1 cells: Cells activated only by nonnoxious stimuli. They were divided into — 1A: hair movement and/or touch and 1B: hair movement and/or touch and pressure or pressure only. Class 2 cells: Cells driven by both nonnoxious and noxious stimuli, divided into — 2A: hair movement and/or touch, pressure, pinch and/or pin-prick, and 2B: pressure, pinch and/or pin-prick. Class 3 cells: Cells only activated by noxious stimuli (pinch and/or pin-prick). Class 4 cells: Cells responding to joint movement or pressure on deep tissues.Peripheral transcutaneous or sural nerve stimulation clearly showed that class 1 cells were activated only by A fiber input while 68% of classes 2 and 3 cells received A and C input. Histological examination indicated that cells driven only by noxious input were located either in the deepest part or in the marginal zone (lamina I) of the dorsal horn. Nevertheless, some lamina I cells were also driven by both nonnoxious and noxious stimuli. In addition, there is a great deal of overlap between class 1 and class 2 cells. This fact was confirmed by considering the wide distribution in the dorsal horn of cells receiving A and C input. However, spinal organization of the different classes of cells consists of a preferential distribution rather than a strict lamination. This study indicates that properties of dorsal horn interneurones in the rat have a high degree of similarity with those previously described in other species (cat and monkey).This work was supported by the C.N.R.S. (E.R.A. 237).     

Vascular permeability changes in tumours of the peripheral nervous system

Summary Vascular permeability changes were examined in 34 tumours of the peripheral nervous system by immunohistochemical demonstration of serum proteins as endogenous tracers. The blood-tumour barrier was impaired in the reticular (Antoni type B) portions of neurinomas (Schwannomas) and in cutaneous neurofibromas but was similar to the normal blood-nerve barrier in fibrillary (Antoni type A) neurinomas, in most neurofibromas, in ganglioneuromas and in anaplastic tumours. These differences in permeability are discussed in relation to aspects of pathological tumour vascularization, the histogenesis of microcystic changes, and systemic therapeutic approaches.Presented at the International Symposium on Advances in Neuro-Oncology, Sanremo, 1990     

Heterosynaptic modulation of the dorsal root potential in the turtle spinal cord in vitro

In the somatosensory system, the flow of sensory information is regulated at early stages by presynaptic inhibition. Recent findings have shown that the mechanisms generating the primary afferent depolarization (PAD) associated with presynaptic inhibition are complex, with some components mediated by a non-spiking mechanism. How sensory inputs carried by neighbouring afferent fibres interact to regulate the generation of PAD, and thus presynaptic inhibition, is poorly known. Here, we investigated the interaction between neighbouring primary afferents for the generation of PAD in an in vitro preparation of the turtle spinal cord. To monitor PAD we recorded the dorsal root potential (DRP), while the simultaneous cord dorsum potential (CDP) was recorded to assess the population postsynaptic response. We found that the DRP and the CDP evoked by a primary afferent test stimulus was greatly reduced by a conditioning activation of neighbouring primary afferents. This depression had early and late components, mediated in part by GABA_A and GABA_B receptors, since they were reduced by bicuculline and SCH 50911 respectively. However, with the selective stimulation of C and Aδ fibres in the presence of TTX, the early and late depression of the DRP was replaced by facilitation of the GABAergic and glutamatergic components of the TTX-resistant DRP. Our findings suggest a subtle lateral excitatory interaction between primary afferents for the generation of PAD mediated by a non-spiking mechanism that may contribute to shaping of information transmitted by C and Aδ fibres in a spatially confined scale in analogy with the retina and olfactory bulb.     

The perineuronal glial tissue of spinal ganglia. Quantitative changes in the rabbit from youth to extremely advanced age

The volumes of the nerve cell bodies and those of the enveloping satellite cell sheaths from spinal ganglia were determined by morphometric methods applied to electron micrographs in young, adult, old and very old rabbits. The mean volume of the nerve cell bodies increased progressively with age; this is probably related to the increase with age of the body size of the rabbits studied. The mean volume of the satellite cell sheaths did not differ significantly in young, adult and old animals, but was significantly smaller in very old animals. It is extremely unlikely that this marked reduction in the volume of the satellite cell sheath is the result of a pathological process. The mean value of the volume ratio between the satellite cell sheaths and the related nerve cell bodies did not differ significantly in young and adult animals, but was significantly smaller in old and very old animals. This ratio was particularly low in very old animals. Our analysis showed that in each age group the volume of the satellite cell sheath is linearly related to the volume of the related nerve cell body. This result suggests that in rabbit spinal ganglia the quantitative relations between glial and nervous tissue are tightly controlled throughout life. It is suggested that ganglionic neurons release signals to influence and control the volume of their associated glial tissue. Since satellite cells have important support roles for the neurons they surround, it is likely that the marked reduction in the volume of perineuronal sheaths in the extremely advanced age is accompanied by a reduction of those roles, with negative consequences for neuronal activity. C. Martinelli and P. Sartori contributed equally to this paper.     

A case of angioimmunoblastic lymphadenopathy with involvement of the nervous system

Summary A case of angioimmunoblastic lymphadenopathy with a short survival time is reported. At autopsy there was generalized lymphadenopathy with the characteristic histological pattern and widespread involvement of many organs including the meninges and the peripheral nervous system. The relation to morphologically comparable diseases of the nervous system with a suspected viral aetiology is discussed.     

The perikaryal surface of spinal ganglion neurons: differences between domains in contact with satellite cells and in contact with the extracellular matrix

 The perikaryal surface of spinal ganglion neurons undergoes dynamic changes throughout life. In particular, numerous slender projections develop and retract continuously from this surface. We showed previously that the outgrowth of these projections, while an intrinsic property of spinal ganglion neurons, is also influenced by the surrounding microenvironment. Since the latter consists of satellite cells and the extracellular matrix, we sought to determine the relative contributions of each of these components to the outgrowth of perikaryal projections. To this end, we took advantage of a little known characteristic of the satellite cell sheaths: in the rabbit, these sheaths can exhibit gaps that leave the nerve cell body surface directly exposed to the extracellular matrix. We compared the surface domains covered by satellite cells with those in direct contact with the extracellular matrix. We found that the perikaryal projections are abundant in the former domains but are absent in the latter. We also found that the perineuronal extracellular matrix of rabbit spinal ganglia contains laminin and fibronectin, two glycoproteins that have been reported to promote the growth of axonal processes from sensory ganglion neurons. Laminin and fibronectin were also present at the level of the gaps in the satellite cell sheath. These results: (1) provide additional evidence that environmental factors influence the outgrowth of perikaryal projections from spinal ganglion neurons; (2) suggest that satellite cells permit the outgrowth of these projections; (3) suggest that in the spinal ganglia of adult rabbits the perineuronal extracellular matrix is not in itself able to promote the outgrowth of these projections. This study provides a further example of the influence that supporting neuroglial cells have on sensory ganglion neurons. Accepted: 30 July 1998     

C1型尼曼-匹克症小鼠脊髓胶质细胞的活性变化

目的通过观察C1型尼曼-匹克症小鼠不同脊髓节段星形胶质细胞和小胶质细胞的活性变化,探讨Npc1基因突变对脊髓发育的影响。方法 Npc1~(+/-)小鼠交配繁殖产生Npc~(1-/-)(n=3)和Npc1~(+/+)小鼠(n=3),PCR检测新生小鼠的基因型;选取35日龄的Npc1~(-/-)和Npc1~(+/+)小鼠,采用免疫荧光方法观察对比脊髓不同节段(颈、胸、腰、骶)星形胶质细胞和小胶质细胞的活性变化。采用免疫双染色检测胶质细胞中炎性因子的表达情况,采用免疫印迹方法检测白细胞介素-1β(IL-1β)、SMI31和磷酸化的tau蛋白表达情况。结果在35日龄Npc1~(-/-)小鼠脊髓的各个节段,其背角和腹角的星形胶质细胞和小胶质细胞的活性均明显增强(P0.05),并伴随细胞炎性因子IL-1β表达量的显著增加;同时,脊髓神经丝蛋白和骨架蛋白tau蛋白发生超磷酸化。结论 Npc1基因突变引起脊髓神经胶质细胞发生病理性变化,可能是脊髓神经元病理性损伤的重要原因。