Myelin Gangliosides: An Unusual Pattern in the Avian Central Nervous System

Abstract: Gangliosides were isolated from purified myelin obtained from brain and spinal cord of mature chickens and pigeons. Total concentrations were approximately two- to fivefold greater than for previously reported mammalian species, and their patterns also differed in containing significantly more sialosylgalactosylceramide (G_M4). The latter comprised one-third to one-fourth of total myelin ganglioside, approximately equivalent to G_M1 (II³NeuNAc-GgOse₄Cer). As in mammals, G_M4 of avian CNS appeared to be localized in myelin. Fatty acids of this ganglioside included both the hydroxy- and unsubstituted types. and, long-chain bases were almost entirely C₁₈. Ganglioside G_M1 split into two closely migrating bands on TLC, the slower of which resembled mammalian G_M1 in having stearate as the main fatty acid with a measurable amount (10%) of C₂₀-sphingosine; the faster band had predominantly longer-chain fatty acids and very little C₂₀-sphingosine.     

Characterization and Regional Distribution of Individual Gangliosides in Goldfish Central Nervous System

Gangliosides were partially purified from goldfish brain and fractionated by DEAE Fractogel column chromatography. Each fraction was then analyzed by HPTLC and also by HPLC after conversion of the gangliosides to 2,4-dinitrophenylhydrazides. The tetrasialoganglioside GQ1c was found to constitute more than 50% of the total gangliosides. Gangliosides in smaller quantities were also tentatively identified. These included GT1b, GT1c, GT2, GT3, GD1a, and several others. By using this information, the amounts of individual gangliosides in various regions of goldfish central nervous system were compared. Although all areas of brain examined contained similar concentrations of gangliosides, with GQ1c as the predominant component, retina and optic nerve contained significantly lower concentrations of GQ1c, and GM3 was the major component.     

Glycolipid-Enriched Caveolae and Caveolae-Like Domains in the Nervous System

Abstract: Recent years have been characterized by a booming interest in research on caveolae and caveolae-like membrane domains. The interest in this subject grew further, when their involvement in fundamental membrane-associated events, such as signal transmission and lipid/protein sorting, was postulated. Substantial progress has been reached in understanding the biological role of membrane domains in eukaryotic cells. The neuron, however, which perhaps represents one of the greatest challenges to research on membrane traffic and function, has only been partially investigated. The purpose of the present review is to survey this issue in the nervous system. We confine ourselves to the presence of membrane domains in the nervous system and discuss this in the context of three facts: first, glycolipids are peculiarly enriched in both caveolae and caveolae-like domains and are particularly abundant in the nervous system; second, the neuron is characterized by a basic dual polarity, similar in this respect to other polarized cells, where the role of glycolipid-enriched domains for lipid/protein sorting has been better ascertained; and third, neurons evolved from, and are related to, simpler eukaryotic cells, allowing us to find analogies with more investigated nonneuronal cells.     

P2 Protein in Oligodendrocytes and Myelin of the Rabbit Central Nervous System

P2 protein, a myelin-specific protein, was detected immunocytochemically and biochemically in rabbit central nervous system (CNS) myelin. P2 protein was synthesized by rabbit oligodendrocytes and was present in varying amounts throughout the rabbit CNS. Comparison of P2 and myelin basic protein (MBP) stained sections revealed that P2 antiserum did not stain all myelin sheaths within the rabbit CNS. The proportion of myelin sheaths stained by P2 antiserum and the amount of P2 detected biochemically were greater in more caudal regions of the rabbit CNS. The highest concentration of P2 protein was found in rabbit spinal cord myelin, where P2 antiserum stained the majority of myelin sheaths. P2 protein was barely detectable biochemically in myelin isolated from frontal cortex, and in sections of frontal cortex only occasional myelin sheaths reacted with P2 antiserum. These results suggest the the regional variations in the amount of P2 protein are dut to regional differences in the number of myelin sheaths that contain P2 protein. P2 protein was detected immunocytochemically and biochemically in rabbit sciatic nerve myelin. Immunocytochemically, P2 antiserum only stained a portion of the myelin sheaths present. The myelin sheaths not reacting with P2 antiserum had small diameters and represented less than 10% of the total myelinated fibers.     

Composition and Metabolism of Gangliosides in Rat Peripheral Nervous System During Development

Abstract: Ganglioside composition of rat trigeminal nerve was studied during development in order to understand the changes that occur as a result of cellular differentiation in the nerve. The ganglioside composition of the trigeminal nerve was entirely different from that of brain. The major gangliosides in adult trigeminal nerve were GM₃, GD₃, and LM₁ (sialosyl-lactoneotetraosylceramide or sialosylparagloboside). The structure of LM₁ and other gangliosides was established by enzymatic degradation and by analysis of the products of acid hydrolysis. At 2 days after birth, when the Schwann cells were immature, GM₃ and GD₃ were the major gangliosides in the nerve, 50 and 18 mol %, respectively. As the nerve developed and Schwann cells proliferated and myelinated the axons, the mol % of GM₃ and GD₃ reduced and that of LM₁ steadily increased. Polysialogangliosides did not change drastically with nerve development. The rate of deposition of LM₁ in the nerve with age was very similar to that of myelin marker lipids, cerebrosides, and sulfatides; thus, deposition appears to be localized mainly in the rat nerve myelin. LM₁ also had long-chain fatty acids 22:0 and 24:0, which are not usually found in CNS gangliosides. The ganglioside pattern of the rat trigeminal nerve was very similar to that of rat sciatic nerve, but was different from that of rabbit and chicken sciatic nerve. The activity of the two key enzymes involved in the metabolism of GM₃, viz., CMP-N-acetylneuraminic acid:lactosylceramide sialyltransferase and UDP-N-acetylgalactosamine:GM₃-N-acetylgalactosaminyltransferase, was also studied during development of the nerve and brain. The developmental profiles of both enzymes were consistent with the amounts of GM₃ present in the nerve.     

Immunochemical Identification of 2', 3'-Cyclic Nucleotide 3'-Phosphodiesterase in Central and Peripheral Nervous System Myelin, the Wolfgram Protein Fraction, and Bovine Oligodendrocytes

Abstract: Myelin proteins and the total Wolfgram protein fraction were isolated from the CNS of several mammalian species and characterized with rabbit anti-bovine 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNP) antisera after sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electrophoretic transfer to nitrocellulose membranes. The corresponding CNP proteins cross-reacted across all species examined, suggesting that the CNP amino acid sequence was fairly well conserved in all six species. The same corresponding proteins were also identified immunochemically in the crude total Wolfgram protein fraction in the region of the W1 myelin protein, thus further supporting and extending two different previous reports indicating a relationship between CNP and the W1 protein. In addition to these CNS enzyme sources, peripheral nervous system CNP (rabbit and rat sciatic nerve) was also recognized by these same rabbit anti-bovine (CNS) CNP antisera. CNP was also detected in freshly isolated delipidated bovine oligodendrocyte membranes. These results suggest that rabbit anti-bovine CNP antisera may be of use in localization and structural studies of this enzyme in several different species and will permit clear identification of CNP in oligodendrocytes and their isolated membrane fractions.     

Tumor Necrosis Factor-related Apoptosis-inducing Ligand (TRAIL) Signaling and Cell Death in the Immature Central Nervous System after Hypoxia-Ischemia and Inflammation

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a member of the TNF family. The interaction of TRAIL with death receptor 4 (DR4) and DR5 can trigger apoptotic cell death. The aim of this study was to investigate the role of TRAIL signaling in neonatal hypoxia-ischemia (HI). Using a neonatal mouse model of HI, mRNA, and protein expression of TRAIL, DR5 and the TRAIL decoy receptors osteoprotegerin (OPG), mDcTRAILR1, and mDcTRAILR2 were determined. In vitro, mRNA expression of these genes was measured in primary neurons and oligodendrocyte progenitor cells (OPCs) after inflammatory cytokine (TNF-α/IFN-γ) treatment and/or oxygen and glucose deprivation (OGD). The toxicity of these various paradigms was also measured. The expression of TRAIL, DR5, OPG, and mDcTRAILR2 was significantly increased after HI. In vitro, inflammatory cytokines and OGD treatment significantly induced mRNAs for TRAIL, DR5, OPG, and mDcTRAILR2 in primary neurons and of TRAIL and OPG in OPCs. TRAIL protein was expressed primarily in microglia and astroglia, whereas DR5 co-localized with neurons and OPCs in vivo. OGD enhanced TNF-α/IFN-γ toxicity in both neuronal and OPC cultures. Recombinant TRAIL exerted toxicity alone or in combination with OGD and TNF-α/IFN-γ in primary neurons but not in OPC cultures. The marked increases in the expression of TRAIL and its receptors after cytokine exposure and OGD in primary neurons and OPCs were similar to those found in our animal model of neonatal HI. The toxicity of TRAIL in primary neurons suggests that TRAIL signaling participates in neonatal brain injury after inflammation and HI.     

中枢神经系统神经胶质细胞对神经病理性疼痛的调节作用

神经病理性疼痛是一种临床的常见疾病,严重影响了患者及家属的生活质量,给社会带来了沉重的负担。神经病理性疼痛的发病机制及有效治疗仍在探索中。中枢神经系统内有三种胶质细胞,包括小胶质细胞、星形胶质细胞以及少突胶质细胞。近来有研究发现,这三种胶质细胞可通过活化、产生和释放细胞因子等途径参与神经病理性疼痛的调节。探索神经胶质细胞的多种复杂功能或作用机制来充分认识胶质细胞的特点,为今后神经病理性疼痛的临床治疗提供新的思路。本文通过研究小胶质细胞、星形胶质细胞以及少突胶质细胞的特点及其对神经病理性疼痛的影响,并分析中枢神经系统胶质细胞与疼痛治疗之间的相关性,旨在总结神经病理性疼痛的发生和发展过程中小胶质细胞、星状胶质细胞及少突胶质细胞的调节作用。     

Characterization and Biosynthesis of Cyclic-AMP-Binding Proteins in the Rat Central Nervous System

Cyclic-AMP-binding proteins in membrane and soluble fractions from rat forebrain were compared; membrane fractions included smooth and rough microsomes and a plasma membrane fraction enriched in synaptic membranes. Protein fractions were treated with 8-azido-[32P]cyclic AMP and ultraviolet irradiation to covalently tag cyclic-AMP-binding proteins. Labeled proteins were then analyzed by two-dimensional gel electrophoresis (2DGE) and fluorography. The soluble CNS proteins contained two major cyclic-AMP-binding species at 48K (48K 5.5 and 48K 5.45), differing slightly in their isoelectric points. Another protein was seen at 54K (54K 5.3) adjacent to the beta-tubulin subunits in the 2D electrophoretogram. The analysis of the smooth microsome and plasma membrane fractions differed from the soluble fraction in that there were two cyclic-AMP-binding proteins adjacent to the beta-tubulin region (54K 5.3 and 52K 5.3) differing slightly in apparent molecular weight. The membrane fractions also contained a cyclic-AMP-binding protein at 54K 5.8. The 52K 5.3 and 54K 5.8 species were unique to the membrane fractions. The rough microsomes did not contain detectable amounts of cyclic-AMP-binding proteins. Free polysomes were isolated from brain tissue, and translation products were analyzed by cyclic AMP affinity chromatography and immunopurification with antibodies to the brain specific type II regulatory subunit. The translation products that were found to bind cyclic AMP Sepharose are as follows: 48K 5.5, 48K 5.45, 52K 5.3, and 54K 5.8. These species comigrated with proteins that were photoaffinity-labeled in cytosol and membrane fractions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cytokine-Induced Inflammation in the Central Nervous System Revisited

Cytokines play an essential role as mediators of the immune response. They usually function as part of a network of interactive signals that either activate, enhance, or inhibit the ensuing reaction. An important contribution of this cytokine cascade is the induction of an inflammatory response that recruits and activates subsets of leukocytes that function as effector cells in the response to the sensitizing antigen. Proinflammatory cytokines activate endothelial cells (EC) to express adhesion molecules and induce the release of members of the chemokine family, thus focusing and directing the inflammatory response to sites of antigen recognition. However, the vasculature of the central nervous system (CNS) is highly specialized and restricts the access of components of the immune system to the CNS compartment. In this review, we address the question as to whether endothelial cells in the CNS respond differently to specific cytokines known to induce either a proinflammatory effect or a regulatory effect in systemic vascular beds.     

A Novel Gelsolin Isoform Expressed by Oligodendrocytes in the Central Nervous System

Abstract: Two isoforms of the Ca²⁺-sensitive, actin-binding protein gelsolin have been identified thus far; one is an intracellular protein, cytoplasmic gelsolin, and the other is a secretory protein called plasma gelsolin. Gelsolin expression in the mammalian CNS appears to be localized mainly to oligodendrocytes where it is presumed that the cytoplasmic isoform predominates. Here, we show that oligodendrocytes not only contain cytoplasmic gelsolin, but they also express a novel gelsolin isoform that we have named gelsolin-3. Cytoplasmic gelsolin, plasma gelsolin, and gelsolin-3 arise by alternative splicing from the same gene. The N-terminal amino acid sequence unique to gelsolin-3 is shown to be encoded by a single exon in a region previously thought to be an intron in the human gelsolin gene. In situ hybridization analysis confirmed that gelsolin-3 mRNA is localized primarily to oligodendrocytes in rat brain. In other tissues, gelsolin-3 shows a more restricted pattern of expression than cytoplasmic gelsolin. These data support the view that the gelsolin isoforms have differential roles in the regulation of the actin cytoskeleton.     

TRPV1通道在中枢神经系统中的功能

TRPV1（transient receptor potential vanilloid 1）是在机体广泛分布的非选择性阳离子通道,能被氢离子、高温以及其它内源性和外源性配体激活.其在外周神经系统中主要参与伤害性高温的感受以及痛觉过敏等生理机制.TRPV1在中枢神经系统中功能的研究进展主要体现在突触传递,体温调节,痛觉的调制和细胞凋亡等方面.TRPV1的激活降低突触前谷氨酸的释放及增强已存在的突触后AMPA受体的作用,从而增强了突触传递效能.外周的TRPV1通过激活能够抑制血管的收缩和生热作用,从而抑制体温的升高,当TRPV1被阻断时就发生体温过高,而TRPV1体温调节的中枢作用机制可能是通过直接作用于体温调节中枢.脑干的痛觉调制环路的激活TRPV1可以引起谷氨酸盐的释放,进而激活突触后I类mGlu受体以及NMDA受体,从而起到镇痛的功能.另外近年发现TRPV1在中枢也参与呕吐、呼吸、心率及血压的调节.     

Gangliosides of Human Cerebral Astrocytomas

Abstract: Ganglioside content and composition were examined in a series of 25 human gliomas, which were graded histologically by the criteria of Kerno-han. The concentration of total gangliosides (lpid-bound sialic acid [LBSA]) was decreased with respect to normal brain tissue in nearly all tumors and the extent of reduction correlated with the stage of tumor anaplasia. The distribution of individual gangliosides was altered in glial tumor tissue with an increase in proportion of the structurally simple gangliosides and reduction of polysialogangliosides. The most consistent and significant difference was the elevation of proportion of ganglioside GD3 from 4–5% of total LBSA in normal brain to 20% in the astrocytoma grade IV. The proportions of gangliosides GM2 and GD2 were also found to be elevated in all grades of the tumors. The simplification of ganglioside composition seems to be associated with transformation of the astrocyte with the accumulation of the simpler gangliosides, since the changes resemble those reported with in vitro transformation rather than those of analyses of preparations of purified glial cells.     

Myelin Gangliosides of Human Peripheral Nervous System: An Enrichment of GM1 in the Motor Nerve Myelin Isolated from Cauda Equina

Myelins of the PNS were isolated from human motor and sensory nerves of cauda equina, and their ganglioside compositions were compared. The predominant ganglioside in the human PNS myelins, both from motor and sensory nerves, was LM1 (sialosylneolactotetraosylceramide). Sialosyl-nLc6Cer and disialosyl-nLc4Cer, GD3, GM3, and GD1b were detected as common components of the two nerve myelins. Furthermore, it was revealed that the motor nerve myelin contained GM1 (about 15% of total gangliosides), whereas sensory nerve myelin contained only a trace amount of GM1 (less than 5%), by TLC analyses together with TLC immunostaining using anti-GM1 antibody. As for the disialoganglioside fraction, the content of GD1a, as well as that of GM1, differed in motor and sensory nerves. Thus, the different contents of the ganglioseries gangliosides in human motor and sensory nerve myelins were demonstrated.     

In Vivo and In Vitro Expression of Gangliosides in Chick Retina Müller Cells

The expression of gangliosides of the lactosylceramide (LC) and of the gangliotetraosylceramide (GTC) series on the surface of cells from the chick neural retina was investigated by double-color indirect immunofluorescence. GD3 was assumed to be representative of LC and was detected using a specific monoclonal antibody. GM1 was assumed to be representative of GTC and was detected using the binding of cholera toxin followed by the binding of cholera toxin antibodies. The expression of polysialosylated GTC (polysialosyl-GTC) was detected using the cholera toxin-cholera toxin antibody experimental approach, after conversion of polysialosyl-GTC to GM1 by treatment of the cells with neuraminidase. In retinas from 6-day-old embryos (R6), most cells (approximately 80%) expressed GD3 but not GTC. After culturing for 7 days, (R6+7), the expression of GTC was found confined to neuron-like cells; flat cells derived from Müller cells expressed GD3 but were negative for GTC expression. On the other hand, postmitotic Müller cells obtained from 13-day-old embryo (R13) or 1-day-old hatched chick retina (RP1) expressed GD3, GM1, and polysialosyl-GTC but were unable to maintain the expression of these GTCs when kept in culture for several days. According to these results, retinal cells can be defined on the basis of their ganglioside expression as follows: (a) retinoblasts, by the expression of GD3; (b) postmitotic neuronal cells, by the expression of GTC; and (c) postmitotic Müller cells, by the expression of GD3 and GTC.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cytokine Gene Expression Within the Central Nervous System

1. The identification of cytokine genes expressed in the central nervous system is critical to understanding the immune network in various diseases of brain, such as infection, degeneration, and malignancy.2. Expression of cytokine genes in human astrocytoma cell lines and in fresh brain specimens was studied by the reverse-transcribed/polymerase chain reaction method.3. The correlation between clinical malignancy and cytokine gene expression within malignant glioma was examined, especially regarding the relevancy of inhibitory cytokines, such as transforming growth factor- and interleukin-10.     

The Presence of Phospholipase D In Rat Central Nervous System Axolemma

An axolemma-enriched fraction prepared from a purified myelinated axon fraction isolated from rat CNS was found to contain phospholipase D at a specific activity similar to that of a microsomal fraction isolated from whole brain. There was a concomitant threefold enrichment in the specific activity of phospholipase D and acetylcholinesterase in the axolemma-enriched fraction compared with the specific activities of these enzymes in the starting white matter whole homogenate. This axonal phospholipase D may be involved in remodeling of phospholipid, which in turn may affect axonal functions such as ion translocation.     

Gangliosides in Human Fetal Brain

The ganglioside concentration and composition were determined in 42 human fetal brains from gestational week 10 to 22, a period that is morphologically characterized by rapid neuroblast proliferation and migration. The ganglioside concentration was constant during this period, approximately 1 mumol of ganglioside sialic acid/g of fresh tissue weight. At gestational week 10 the ganglioside pattern was dominated by gangliosides of the ganglio b series, with the major ganglioside being GT1b, contributing 40% of total ganglioside sialic acid, whereas GD1b and GD3 contributed only 15 and 10%, respectively. The proportion of b series ganglioside decreased to gestational week 22, with the most pronounced relative reduction affecting GD3, but also GT1b and GD1b to a lesser extent. The ganglioside GQ1b increased in content from gestational week 10 and peaked around week 16. The proportion of GD1a increased markedly between gestational week 12 and 14 and slowly between week 14 and 18 and then increased rapidly from week 20. Ganglioside GM1 underwent a similar change. Gangliosides of the lacto series contributed 6-10% of ganglioside sialic acid between gestational week 10 and 15, and thereafter the proportion slowly decreased. 3'-isoLM1 decreased rapidly in content from gestational week 10 (20 nmol/g of fresh weight) to week 22 (less than 0.5 nmol/g of fresh weight), whereas the gangliosides of the neolacto series (3'-LM1 and 3',8'-LD1) showed a slower and less marked decline in level. The biological significance of the ganglioside changes is discussed.     

In Vitro Retina as an Experimental Model of the Central Nervous System

Abstract Methods are described for isolating adult rabbit retina and maintaining it in a medium designed to resemble CSF. Morphologic, metabolic, and electrophysiologic measurements obtained on the in vitro retinas showed that they remained in a nearly physiological state for at least 8 h, and even after 2 days in vitro they still exhibited a high level of metabolic activity and electrical responsiveness to light. Physiological activity was modified by photic stimulation, and data are presented to document changes in metabolism in response to the changes in function. The isolated retina appears to offer a number of unusual advantages for studying relationships between function and metabolism in organized mammalian central nervous tissue