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Sample records for anterograde axonal transport

  1. Calsyntenin-1 shelters APP from proteolytic processing during anterograde axonal transport

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    Martin Steuble

    2012-06-01

    Endocytosis of amyloid-β precursor protein (APP is thought to represent the major source of substrate for the production of the amyloidogenic Aβ peptide by the β-secretase BACE1. The irreversible nature of proteolytic cleavage implies the existence of an efficient replenishment route for APP from its sites of synthesis to the cell surface. We recently found that APP exits the trans-Golgi network in intimate association with calsyntenin-1, a transmembrane cargo-docking protein for Kinesin-1-mediated vesicular transport. Here we characterized the function of calsyntenin-1 in neuronal APP transport using selective immunoisolation of intracellular trafficking organelles, immunocytochemistry, live-imaging, and RNAi. We found that APP is co-transported with calsyntenin-1 along axons to early endosomes in the central region of growth cones in carriers that exclude the α-secretase ADAM10. Intriguingly, calsyntenin-1/APP organelles contained BACE1, suggesting premature cleavage of APP along its anterograde path. However, we found that APP contained in calsyntenin-1/APP organelles was stable. We further analyzed vesicular trafficking of APP in cultured hippocampal neurons, in which calsyntenin-1 was reduced by RNAi. We found a markedly increased co-localization of APP and ADAM10 in axons and growth cones, along with increased proteolytic processing of APP and Aβ secretion in these neurons. This suggested that the reduced capacity for calsyntenin-1-dependent APP transport resulted in mis-sorting of APP into additional axonal carriers and, therefore, the premature encounter of unprotected APP with its ectodomain proteases. In combination, our results characterize calsyntenin-1/APP organelles as carriers for sheltered anterograde axonal transport of APP.

  2. Dynamics of mitochondrial transport in axons

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    Robert Francis Niescier

    2016-05-01

    Full Text Available The polarized structure and long neurites of neurons pose a unique challenge for proper mitochondrial distribution. It is widely accepted that mitochondria move from the cell body to axon ends and vice versa; however, we have found that mitochondria originating from the axon ends moving in the retrograde direction never reach to the cell body, and only a limited number of mitochondria moving in the anterograde direction from the cell body arrive at the axon ends of mouse hippocampal neurons. Furthermore, we have derived a mathematical formula using the Fokker-Planck equation to characterize features of mitochondrial transport, and the equation could determine altered mitochondrial transport in axons overexpressing parkin. Our analysis will provide new insights into the dynamics of mitochondrial transport in axons of normal and unhealthy neurons.

  3. Dynamics of Mitochondrial Transport in Axons.

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    Niescier, Robert F; Kwak, Sang Kyu; Joo, Se Hun; Chang, Karen T; Min, Kyung-Tai

    2016-01-01

    The polarized structure and long neurites of neurons pose a unique challenge for proper mitochondrial distribution. It is widely accepted that mitochondria move from the cell body to axon ends and vice versa; however, we have found that mitochondria originating from the axon ends moving in the retrograde direction never reach to the cell body, and only a limited number of mitochondria moving in the anterograde direction from the cell body arrive at the axon ends of mouse hippocampal neurons. Furthermore, we have derived a mathematical formula using the Fokker-Planck equation to characterize features of mitochondrial transport, and the equation could determine altered mitochondrial transport in axons overexpressing parkin. Our analysis will provide new insights into the dynamics of mitochondrial transport in axons of normal and unhealthy neurons. PMID:27242435

  4. Oxidative stress inhibits axonal transport: implications for neurodegenerative diseases

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    Fang Cheng

    2012-06-01

    Full Text Available Abstract Background Reactive oxygen species (ROS released by microglia and other inflammatory cells can cause axonal degeneration. A reduction in axonal transport has also been implicated as a cause of axonal dystrophies and neurodegeneration, but there is a paucity of experimental data concerning the effects of ROS on axonal transport. We used live cell imaging to examine the effects of hydrogen peroxide on the axonal transport of mitochondria and Golgi-derived vesicles in cultured rat hippocampal neurons. Results Hydrogen peroxide rapidly inhibited axonal transport, hours before any detectable changes in mitochondrial morphology or signs of axonal degeneration. Mitochondrial transport was affected earlier and was more severely inhibited than the transport of Golgi-derived vesicles. Anterograde vesicle transport was more susceptible to peroxide inhibition than retrograde transport. Axonal transport partially recovered following removal of hydrogen peroxide and local application of hydrogen peroxide inhibited transport, suggesting that the effects were not simply a result of nerve cell death. Sodium azide, an ATP synthesis blocker, had similar effects on axonal transport, suggesting that ATP depletion may contribute to the transport inhibition due to hydrogen peroxide. Conclusions These results indicate that inhibition of axonal transport is an early consequence of exposure to ROS and may contribute to subsequent axonal degeneration.

  5. Axonal transport of ribonucleoprotein particles (vaults).

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    Li, J Y; Volknandt, W; Dahlstrom, A; Herrmann, C; Blasi, J; Das, B; Zimmermann, H

    1999-01-01

    RNA was previously shown to be transported into both dendritic and axonal compartments of nerve cells, presumably involving a ribonucleoprotein particle. In order to reveal potential mechanisms of transport we investigated the axonal transport of the major vault protein of the electric ray Torpedo marmorata. This protein is the major protein component of a ribonucleoprotein particle (vault) carrying a non-translatable RNA and has a wide distribution in the animal kingdom. It is highly enriched in the cholinergic electromotor neurons and similar in size to synaptic vesicles. The axonal transport of vaults was investigated by immunofluorescence, using the anti-vault protein antibody as marker, and cytofluorimetric scanning, and was compared to that of the synaptic vesicle membrane protein SV2 and of the beta-subunit of the F1-ATPase as a marker for mitochondria. Following a crush significant axonal accumulation of SV2 proximal to the crush could first be observed after 1 h, that of mitochondria after 3 h and that of vaults after 6 h, although weekly fluorescent traces of accumulations of vault protein were observed in the confocal microscope as early as 3 h. Within the time-period investigated (up to 72 h) the accumulation of all markers increased continuously. Retrograde accumulations also occurred, and the immunofluorescence for the retrograde component, indicating recycling, was weaker than that for the anterograde component, suggesting that more than half of the vaults are degraded within the nerve terminal. High resolution immunofluorescence revealed a granular structure-in accordance with the biochemical characteristics of vaults. Of interest was the observation that the increase of vault immunoreactivity proximal to the crush accelerated with time after crushing, while that of SV2-containing particles appeared to decelerate, indicating that the crush procedure with time may have induced perikaryal alterations in the production and subsequent export to the axon

  6. Anterograde transport blockade precedes deficits in retrograde transport in the visual projection of the DBA/2J mouse model of glaucoma

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    Christine M Dengler-Crish

    2014-09-01

    Full Text Available Axonal transport deficits have been reported as an early pathology in several neurodegenerative disorders, including glaucoma. However, the progression and mechanisms of these deficits are poorly understood. Previous work suggests that anterograde transport is affected earlier and to a larger degree than retrograde transport, yet this has never been examined directly in vivo. Using combined anterograde and retrograde tract tracing methods, we examined the time-course of anterograde and retrograde transport deficits in the retinofugal projection in pre-glaucomatous (3 month-old and glaucomatous (9-13 month old DBA/2J mice. DBA/2J-Gpnmb+ mice were used as a control strain and were shown to have similar retinal ganglion cell densities as C57BL/6J control mice—a strain commonly investigated in the field of vision research. Using cholera toxin-B injections into the eye and FluoroGold injections into the superior colliculus (SC, we were able to measure anterograde and retrograde transport in the primary visual projection. In DBA/2J, anterograde transport from the retina to superior colliculus (SC was decreased by 69% in the 9-10 month-old age group, while retrograde transport was only reduced by 23% from levels seen in pre-glaucomatous mice. Despite this minor reduction, retrograde transport remained largely intact in these glaucomatous age groups until 13-months of age. These findings indicate that axonal transport deficits occur in semi-functional axons that are still connected to their brain targets. Structural persistence as determined by presence of estrogen-related receptor beta label in the superficial SC was maintained beyond time-points where reductions in retrograde transport occurred, also supporting that transport deficits may be due to physiological or functional abnormalities as opposed to overt structural loss.

  7. The genetics of axonal transport and axonal transport disorders.

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    Jason E Duncan

    2006-09-01

    Full Text Available Neurons are specialized cells with a complex architecture that includes elaborate dendritic branches and a long, narrow axon that extends from the cell body to the synaptic terminal. The organized transport of essential biological materials throughout the neuron is required to support its growth, function, and viability. In this review, we focus on insights that have emerged from the genetic analysis of long-distance axonal transport between the cell body and the synaptic terminal. We also discuss recent genetic evidence that supports the hypothesis that disruptions in axonal transport may cause or dramatically contribute to neurodegenerative diseases.

  8. Neurofilament Polymer Transport in Axons

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    Yan, Yanping; Brown, Anthony

    2005-01-01

    Neurofilament proteins are known to be transported along axons by slow axonal transport, but the form in which they move is controversial. In previous studies on cultured rat sympathetic neurons, we found that green fluorescent protein-tagged neurofilament proteins move predominantly in the form of filamentous structures, and we proposed that these structures are single neurofilament polymers. In the present study, we have tested this hypothesis by using a rapid perfusion technique to capture...

  9. KIF4 Mediates Anterograde Translocation and Positioning of Ribosomal Constituents to Axons*S⃞

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    Bisbal, Mariano; Wojnacki, José; Peretti, Diego; Ropolo, Andrea; Sesma, Juliana; Jausoro, Ignacio; Cáceres, Alfredo

    2009-01-01

    In this study, we have used a combination of biochemical and molecular biology techniques to demonstrate that the C-terminal tail domain of KIF4 directly interacts with P0, a major protein component of ribosomes. Besides, in dorsal root ganglion neurons, KIF4 and P0, as well as other ribosomal constituents, colocalize in clusters distributed along axons and neuritic tips. RNA interference suppression of KIF4 or expression of KIF4 variants lacking the tail domain or mut...

  10. Mitochondrial Transport and Docking in Axons

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    Cai, Qian; Sheng, Zu-Hang

    2009-01-01

    Proper transport and distribution of mitochondria in axons and at synapses are critical for the normal physiology of neurons. Mitochondria in axons display distinct motility patterns and undergo saltatory and bidirectional movement, where mitochondria frequently stop, start moving again, and change direction. While approximately one-third of axonal mitochondria are mobile in mature neurons, a large proportion remains stationary. Their net movement is significantly influenced by recruitment to...

  11. Ndel1-derived peptides modulate bidirectional transport of injected beads in the squid giant axon

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    Michal Segal

    2012-01-01

    Bidirectional transport is a key issue in cellular biology. It requires coordination between microtubule-associated molecular motors that work in opposing directions. The major retrograde and anterograde motors involved in bidirectional transport are cytoplasmic dynein and conventional kinesin, respectively. It is clear that failures in molecular motor activity bear severe consequences, especially in the nervous system. Neuronal migration may be impaired during brain development, and impaired molecular motor activity in the adult is one of the hallmarks of neurodegenerative diseases leading to neuronal cell death. The mechanisms that regulate or coordinate kinesin and dynein activity to generate bidirectional transport of the same cargo are of utmost importance. We examined how Ndel1, a cytoplasmic dynein binding protein, may regulate non-vesicular bidirectional transport. Soluble Ndel1 protein, Ndel1-derived peptides or control proteins were mixed with fluorescent beads, injected into the squid giant axon, and the bead movements were recorded using time-lapse microscopy. Automated tracking allowed for extraction and unbiased analysis of a large data set. Beads moved in both directions with a clear bias to the anterograde direction. Velocities were distributed over a broad range and were typically slower than those associated with fast vesicle transport. Ironically, the main effect of Ndel1 and its derived peptides was an enhancement of anterograde motion. We propose that they may function primarily by inhibition of dynein-dependent resistance, which suggests that both dynein and kinesin motors may remain engaged with microtubules during bidirectional transport.

  12. Axonal transport of enzymes and labeled proteins in experimental axonopathy induced by p-bromophenylacetylurea

    International Nuclear Information System (INIS)

    Axonal transport was studied by several techniques in the sciatic nerves of adult male Sprague-Dawley rats with neuropathy induced by treatment with p-bromophenylacetylurea (BPAU) in dimethylsulfoxide solution. Control rats were treated with solvent alone. BPAU, 200 mg/kg, induced severe muscle weakness in the hindlimbs, beginning after a latent period of 1 week and progressing to near total paralysis by 2 weeks. Axonal transport of the endogenous transmitter enzymes, acetylcholinesterase, dopamine-β-hydroxylase and choline acetyltransferase, was normal at both 2 and 15 days after administration of BPAU, as judged by the accumulation of enzyme activity above and below a set of double ligatures on the sciatic nerve. The velocity of fast anterograde transport of [35S]methionine labeled protein was also unaffected by BPAU. However, 4 abnormalities of transport were detected in BPAU treated rats. These abnormalities are discussed. (Auth.)

  13. Peripheral prostaglandin E2 prolongs the sensitization of nociceptive dorsal root ganglion neurons possibly by facilitating the synthesis and anterograde axonal trafficking of EP4 receptors.

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    St-Jacques, Bruno; Ma, Weiya

    2014-11-01

    Prostaglandin E2 (PGE2), a well-known pain mediator enriched in inflamed tissues, plays a pivotal role in the genesis of chronic pain conditions such as inflammatory and neuropathic pain. PGE2-prolonged sensitization of nociceptive dorsal root ganglion (DRG) neurons (nociceptors) may contribute to the transition from acute to chronic pain. However, the underlying cellular mechanisms are poorly understood. In this study, we tested the hypothesis that facilitating synthesis and anterograde axonal trafficking of EP receptors contribute to PGE2-prolonged nociceptor sensitization. Intraplantar (i.pl.) injection of a stabilized PGE2 analog, 16,16 dimethyl PGE2 (dmPGE2), in a dose- and time-dependent manner, not only elicited primary tactile allodynia which lasted for 1d, but also prolonged tactile allodynia evoked by a subsequent i.pl. injection of dmPGE2 from 1d to 4d. Moreover, the duration of tactile allodynia was progressively prolonged following multiple sequential i.pl. injections of dmPGE2. Co-injection of the selective EP1 or EP4 receptor antagonist, the inhibitors of cAMP, PKA, PKC, PKCε or PLC as well as an interleukin-6 (IL-6) neutralizing antiserum differentially blocked primary tactile allodynia elicited by the 1st dmPGE2 and the prolonged tactile allodynia evoked by the 2nd dmPGE2, suggesting the involvement of these signaling events in dmPGE2-induced nociceptor activation and sensitization. Co-injection of a selective COX2 inhibitor or two EP4 antagonists prevented or shortened inflammagen-prolonged nociceptor sensitization. I.pl. injection of dmPGE2 or carrageenan time-dependently increased EP4 levels in L4-6 DRG neurons and peripheral nerves. EP4 was expressed in almost half of IB4-binding nociceptors of L4-6 DRG. Taken together, our data suggest that stimulating the synthesis and anterograde axonal trafficking to increase EP4 availability at the axonal terminals of nociceptors is likely a novel mechanism underlying PGE2-prolonged nociceptor

  14. Dynamics of oligodendrocyte responses to anterograde axonal (Wallerian) and terminal degeneration in normal and TNF-transgenic mice

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    Drøjdahl, Nina; Fenger, Christina; Nielsen, Helle H;

    2004-01-01

    larger levels in the TNF-transgenics. At 5 days after axonal transection, numbers of oligodendrocytes and myelin basic protein (MBP) mRNA expression in the denervated dentate gyrus in TNF-transgenic mice had increased to the same extent as in nontransgenic littermates. At this time, transgenics showed a...

  15. Anterograde Amnesia

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    Serap Erdogan

    2010-08-01

    Full Text Available Memory can be divided into two categories (i.e. short term memory and long term memory according to time span. Information at our long term memory that can be remembered with conscious effort are placed in declarative memory. Information that can not be remembered conciously are placed in nondeclarative memory. The definition of anterograde amnesia is inability to generate new memories after the event causing amnesia. Episodic and semantic memories are usually unaffected among patients’ who had such amnesia. Anterograde amnesia could mostly result from head trauma but in some cases the cause could be serebrovascular events, Wernicke-Korsakoff Syndrome, santral nervous system enfections, anoxia or various substances. Medial temporal lobe and medial diencephalon are two brain regions mainly related with this condition. Medial temporal lobe is consisted of hippocampus, amygdala, parahippocampal cortex, perirhinal cortex and entorhinal cortex. Hypothalamus, thalamus, mamillary bodies and several thalamic nucleases compose medial diencephalon. Fornix and rarely serebellum damage may also play role in the development of anterograde amnesia. After the famous H.M case, who had anterograde amnesia after an epileptic surgery operation, hippocampus has been placed in the focus of memory researches. In the literature there are several reports evaluating brain tissues of amnesic patients at postmortem stage. Postmortem histological evaluations consistently revealed hippocampal neuronal loss among these patients’ brain tissues. Benzodiazepines usually cause short term anterograde amnesia. Benzodiazepine receptors are allosteric modulatory sites on gamma-aminobutyric acid-A (GABA-A receptors. GABA-A receptors composed of five subunits and anterograde amnesia emerges by means of alfa 1 subunit. Anterograde amnesia has been suggested to occur by the blocking of long term potentiation in hippocampus and piriform cortex. For the treatment of the anterograde

  16. Synaptic Democracy and Vesicular Transport in Axons

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    Bressloff, Paul C.; Levien, Ethan

    2015-04-01

    Synaptic democracy concerns the general problem of how regions of an axon or dendrite far from the cell body (soma) of a neuron can play an effective role in neuronal function. For example, stimulated synapses far from the soma are unlikely to influence the firing of a neuron unless some sort of active dendritic processing occurs. Analogously, the motor-driven transport of newly synthesized proteins from the soma to presynaptic targets along the axon tends to favor the delivery of resources to proximal synapses. Both of these phenomena reflect fundamental limitations of transport processes based on a localized source. In this Letter, we show that a more democratic distribution of proteins along an axon can be achieved by making the transport process less efficient. This involves two components: bidirectional or "stop-and-go" motor transport (which can be modeled in terms of advection-diffusion), and reversible interactions between motor-cargo complexes and synaptic targets. Both of these features have recently been observed experimentally. Our model suggests that, just as in human societies, there needs to be a balance between "efficiency" and "equality".

  17. Disruption of mitochondrial DNA replication in Drosophila increases mitochondrial fast axonal transport in vivo.

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    Rehan M Baqri

    Full Text Available Mutations in mitochondrial DNA polymerase (pol gamma cause several progressive human diseases including Parkinson's disease, Alper's syndrome, and progressive external ophthalmoplegia. At the cellular level, disruption of pol gamma leads to depletion of mtDNA, disrupts the mitochondrial respiratory chain, and increases susceptibility to oxidative stress. Although recent studies have intensified focus on the role of mtDNA in neuronal diseases, the changes that take place in mitochondrial biogenesis and mitochondrial axonal transport when mtDNA replication is disrupted are unknown. Using high-speed confocal microscopy, electron microscopy and biochemical approaches, we report that mutations in pol gamma deplete mtDNA levels and lead to an increase in mitochondrial density in Drosophila proximal nerves and muscles, without a noticeable increase in mitochondrial fragmentation. Furthermore, there is a rise in flux of bidirectional mitochondrial axonal transport, albeit with slower kinesin-based anterograde transport. In contrast, flux of synaptic vesicle precursors was modestly decreased in pol gamma-alpha mutants. Our data indicate that disruption of mtDNA replication does not hinder mitochondrial biogenesis, increases mitochondrial axonal transport, and raises the question of whether high levels of circulating mtDNA-deficient mitochondria are beneficial or deleterious in mtDNA diseases.

  18. Completely assembled virus particles detected by transmission electron microscopy in proximal and mid-axons of neurons infected with herpes simplex virus type 1, herpes simplex virus type 2 and pseudorabies virus

    International Nuclear Information System (INIS)

    The morphology of alphaherpesviruses during anterograde axonal transport from the neuron cell body towards the axon terminus is controversial. Reports suggest that transport of herpes simplex virus type 1 (HSV-1) nucleocapsids and envelope proteins occurs in separate compartments and that complete virions form at varicosities or axon termini (subassembly transport model), while transport of a related alphaherpesvirus, pseudorabies virus (PRV) occurs as enveloped capsids in vesicles (assembled transport model). Transmission electron microscopy of proximal and mid-axons of primary superior cervical ganglion (SCG) neurons was used to compare anterograde axonal transport of HSV-1, HSV-2 and PRV. SCG cell bodies were infected with HSV-1 NS and 17, HSV-2 2.12 and PRV Becker. Fully assembled virus particles were detected intracellularly within vesicles in proximal and mid-axons adjacent to microtubules after infection with each virus, indicating that assembled virions are transported anterograde within axons for all three alphaherpesviruses.

  19. Peri-Golgi vesicles contain retrograde but not anterograde proteins consistent with the cisternal progression model of intra-Golgi transport

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    José A Martínez-Menárguez; Prekeris, Rytis; Oorschot, Viola M J; Scheller, Richard; Slot, Jan W.; Geuze, Hans J.; Klumperman, Judith

    2001-01-01

    A cisternal progression mode of intra-Golgi transport requires that Golgi resident proteins recycle by peri-Golgi vesicles, whereas the alternative model of vesicular transport predicts anterograde cargo proteins to be present in such vesicles. We have used quantitative immuno-EM on NRK cells to distinguish peri-Golgi vesicles from other vesicles in the Golgi region. We found significant levels of the Golgi resident enzyme mannosidase II and the transport machinery proteins giantin, KDEL-rece...

  20. Coordinating gene expression and axon assembly to control axon growth: potential role of GSK3 signaling

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    Fengquan Zhou

    2012-02-01

    Full Text Available Axon growth requires coordinated regulation of gene expression in the neuronal soma, anterograde transport of synthesized raw materials along the axon, and assembly of cytoskeleton and membranes in the nerve growth cone. Glycogen synthase kinase 3 (GSK3 signaling has recently been shown to play key roles in regulation of axonal transport and cytoskeletal assembly during axon growth. GSK3 signaling is also known to regulate gene expression via controlling the functions of many transcription factors, suggesting that GSK3 may be an important regulator of gene transcription supporting axon growth. Here we will review signaling pathways that control local axon assembly at the growth cone and gene expression in the soma during developmental or regenerative axon growth and discuss the potential involvement of GSK3 signaling in these processes, with a particular focus on how GSK3 signaling modulates the function of axon growth-associated transcription factors.

  1. Microglial reactivity correlates to the density and the myelination of the anterogradely degenerating axons and terminals following perforant path denervation of the mouse fascia dentata

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    Jensen, M B; Hegelund, I V; Rom Poulsen, Frantz;

    1999-01-01

    Transection of the entorhino-dentate perforant path is a well known model for lesion-induced axonal sprouting and glial reactions in the rat. In this study, we have characterized the microglial reaction in the dentate molecular layer of the SJL/J and C57Bl/6 mouse. The morphological transformatio...

  2. A Bovine Herpesvirus Type 1 Mutant Virus Specifying a Carboxyl-Terminal Truncation of Glycoprotein E Is Defective in Anterograde Neuronal Transport in Rabbits and Calves▿ †

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    Liu, Z. F.; M.C.S. Brum; Doster, A.; Jones, C.; Chowdhury, S I

    2008-01-01

    Bovine herpesvirus type 1 (BHV-1) is an important component of the bovine respiratory disease complex (BRDC) in cattle. The ability of BHV-1 to transport anterogradely from neuronal cell bodies in trigeminal ganglia (TG) to nerve ending in the noses and corneas of infected cattle following reactivation from latency plays a significant role in the pathogenesis of BRDC and maintenance of BHV-1 in the cattle population. We have constructed a BHV-1 bacterial artificial chromosome (BAC) clone by i...

  3. In vivo imaging of axonal transport using MRI: aging and Alzheimer's disease

    International Nuclear Information System (INIS)

    MRI using manganese as a trans-synaptic axonal tracing agent can unveil dynamics of axonal transport in living subjects. We use this technology to test the hypotheses if impaired axonal transport is a significant pathophysiological process in aging and early Alzheimer's disease (AD) and in part accounting for ''selective vulnerability'' of projection neurons in AD. To allow quantitative assessment of axonal transport in vivo, we developed voxel-based statistical mapping technology as well as a tracer kinetic modeling method based on mass transport for manganese-enhanced MRI to estimate axonal transport rates in aging rats and AD transgenic mice. These techniques demonstrated manganese-enhanced signal changes in axonal projections of the olfactory tract and decreased axonal transport rates in rodent models of aging and AD. Altered axonal transport may be a critical pathophysiological process in aging and AD. Manganese-enhanced MRI provides exciting opportunities for the investigations of altered axonal transport in AD and related disorders. (orig.)

  4. DBZ regulates cortical cell positioning and neurite development by sustaining the anterograde transport of Lis1 and DISC1 through control of Ndel1 dual-phosphorylation.

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    Okamoto, Masayuki; Iguchi, Tokuichi; Hattori, Tsuyoshi; Matsuzaki, Shinsuke; Koyama, Yoshihisa; Taniguchi, Manabu; Komada, Munekazu; Xie, Min-Jue; Yagi, Hideshi; Shimizu, Shoko; Konishi, Yoshiyuki; Omi, Minoru; Yoshimi, Tomohiko; Tachibana, Taro; Fujieda, Shigeharu; Katayama, Taiichi; Ito, Akira; Hirotsune, Shinji; Tohyama, Masaya; Sato, Makoto

    2015-02-18

    Cell positioning and neuronal network formation are crucial for proper brain function. Disrupted-in-Schizophrenia 1 (DISC1) is anterogradely transported to the neurite tips, together with Lis1, and functions in neurite extension via suppression of GSK3β activity. Then, transported Lis1 is retrogradely transported and functions in cell migration. Here, we show that DISC1-binding zinc finger protein (DBZ), together with DISC1, regulates mouse cortical cell positioning and neurite development in vivo. DBZ hindered Ndel1 phosphorylation at threonine 219 and serine 251. DBZ depletion or expression of a double-phosphorylated mimetic form of Ndel1 impaired the transport of Lis1 and DISC1 to the neurite tips and hampered microtubule elongation. Moreover, application of DISC1 or a GSK3β inhibitor rescued the impairments caused by DBZ insufficiency or double-phosphorylated Ndel1 expression. We concluded that DBZ controls cell positioning and neurite development by interfering with Ndel1 from disproportionate phosphorylation, which is critical for appropriate anterograde transport of the DISC1-complex. PMID:25698733

  5. Slowing of the axonal transport of neurofilament proteins during development

    International Nuclear Information System (INIS)

    We examined age-dependent changes in neurofilament transport in motor axons of the rat sciatic nerve. SDS-PAGE and gel fluorography confirmed that the distribution of labeled neurofilament triplet protein coincides with the major slow component a (SCa) wave in these neurons. The velocity of neurofilament transport was calculated on the basis of the location of the 50th percentile of radioactivity in this wave 33 days after motor neurons were labeled by the intraspinal administration of [3H]leucine and [3H]lysine. Overall, the velocity fell from 1.95 mm/day at 3 weeks of age to 1.12 mm/day at 20 weeks. Between 3 and 10 weeks, it fell at a 6-fold higher rate (0.096 mm/day/week) than between 10 and 20 weeks (0.016 mm/day/week). We also found a marked change in the shape of the slow component wave during development. It appeared to consist of several overlapping peaks moving at slightly different velocities in animals 10 weeks of age or less as compared to a single slower moving peak at 20 weeks. We propose that the velocity of slow axonal transport reflects the level of maturation of the neuron, and that the presence of several overlapping peaks of transported radioactivity in the sciatic nerve of younger animals reflects the presence of several populations of motor axons at different stages of development. We also discuss the relationship between changes in the velocity of neurofilament transport and alterations in the composition of the cytoskeleton that occur as the axon grows in caliber during postnatal development

  6. Axonal Transport Impairment in Chemotherapy-Induced Peripheral Neuropathy

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    Gabriella Nicolini

    2015-08-01

    Full Text Available Chemotherapy-Induced Peripheral Neuropathy (CIPN is a dose-limiting side effect of several antineoplastic drugs which significantly reduces patients’ quality of life. Although different molecular mechanisms have been investigated, CIPN pathobiology has not been clarified yet. It has largely been recognized that Dorsal Root Ganglia are the main targets of chemotherapy and that the longest nerves are the most damaged, together with fast axonal transport. Indeed, this bidirectional cargo-specific transport has a pivotal role in neuronal function and its impairment is involved in several neurodegenerative and neurodevelopmental diseases. Literature data demonstrate that, despite different mechanisms of action, all antineoplastic agents impair the axonal trafficking to some extent and the severity of the neuropathy correlates with the degree of damage on this bidirectional transport. In this paper, we will examine the effect of the main old and new chemotherapeutic drug categories on axonal transport, with the aim of clarifying their potential mechanisms of action, and, if possible, of identifying neuroprotective strategies, based on the knowledge of the alterations induced by each drugs.

  7. Tau phosphorylation affects its axonal transport and degradation

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    Rodríguez-Martín, Teresa; Cuchillo-Ibáñez, Inmaculada; Noble, Wendy; Nyenya, Fanon; Anderton, Brian H; Hanger, Diane P.

    2013-01-01

    Phosphorylated forms of microtubule-associated protein tau accumulate in neurofibrillary tangles in Alzheimer's disease. To investigate the effects of specific phosphorylated tau residues on its function, wild type or phosphomutant tau was expressed in cells. Elevated tau phosphorylation decreased its microtubule binding and bundling, and increased the number of motile tau particles, without affecting axonal transport kinetics. In contrast, reducing tau phosphorylation enhanced the amount of ...

  8. Automated kymograph analysis for profiling axonal transport of secretory granules.

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    Mukherjee, Amit; Jenkins, Brian; Fang, Cheng; Radke, Richard J; Banker, Gary; Roysam, Badrinath

    2011-06-01

    This paper describes an automated method to profile the velocity patterns of small organelles (BDNF granules) being transported along a selected section of axon of a cultured neuron imaged by time-lapse fluorescence microscopy. Instead of directly detecting the granules as in conventional tracking, the proposed method starts by generating a two-dimensional spatio-temporal map (kymograph) of the granule traffic along an axon segment. Temporal sharpening during the kymograph creation helps to highlight granule movements while suppressing clutter due to stationary granules. A voting algorithm defined over orientation distribution functions is used to refine the locations and velocities of the granules. The refined kymograph is analyzed using an algorithm inspired from the minimum set cover framework to generate multiple motion trajectories of granule transport paths. The proposed method is computationally efficient, robust to significant levels of noise and clutter, and can be used to capture and quantify trends in transport patterns quickly and accurately. When evaluated on a collection of image sequences, the proposed method was found to detect granule movement events with 94% recall rate and 82% precision compared to a time-consuming manual analysis. Further, we present a study to evaluate the efficacy of velocity profiling by analyzing the impact of oxidative stress on granule transport in which the fully automated analysis correctly reproduced the biological conclusion generated by manual analysis. PMID:21330183

  9. Distal retinal ganglion cell axon transport loss and activation of p38 MAPK stress pathway following VEGF-A antagonism.

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    Foxton, R; Osborne, A; Martin, K R; Ng, Y-S; Shima, D T

    2016-01-01

    There is increasing evidence that VEGF-A antagonists may be detrimental to neuronal health following ocular administration. Here we investigated firstly the effects of VEGF-A neutralization on retinal neuronal survival in the Ins2(Akita) diabetic and JR5558 spontaneous choroidal neovascularization (CNV) mice, and then looked at potential mechanisms contributing to cell death. We detected elevated apoptosis in the ganglion cell layer in both these models following VEGF-A antagonism, indicating that even when vascular pathologies respond to treatment, neurons are still vulnerable to reduced VEGF-A levels. We observed that retinal ganglion cells (RGCs) seemed to be the cells most susceptible to VEGF-A antagonism, so we looked at anterograde transport in these cells, due to their long axons requiring optimal protein and organelle trafficking. Using cholera toxin B-subunit tracer studies, we found a distal reduction in transport in the superior colliculus following VEGF-A neutralization, which occurred prior to net RGC loss. This phenomenon of distal transport loss has been described as a feature of early pathological changes in glaucoma, Alzheimer's and Parkinson's disease models. Furthermore, we observed increased phosphorylation of p38 MAPK and downstream Hsp27 stress pathway signaling in the retinas from these experiments, potentially providing a mechanistic explanation for our findings. These experiments further highlight the possible risks of using VEGF-A antagonists to treat ocular neovascular disease, and suggest that VEGF-A may contribute to the maintenance and function of axonal transport in neurons of the retina. PMID:27148685

  10. In vivo imaging of axonal transport using MRI: aging and Alzheimer's disease

    Energy Technology Data Exchange (ETDEWEB)

    Minoshima, Satoshi [University of Washington, Departments of Radiology and Bioengineering, 1959 N.E. Pacific Street, RR215, Box 357115, Seattle, WA (United States); Cross, Donna [University of Washington, Department of Radiology, 1959 N.E. Pacific Street, RR215, Box 357115, Seattle, WA (United States)

    2008-03-15

    MRI using manganese as a trans-synaptic axonal tracing agent can unveil dynamics of axonal transport in living subjects. We use this technology to test the hypotheses if impaired axonal transport is a significant pathophysiological process in aging and early Alzheimer's disease (AD) and in part accounting for ''selective vulnerability'' of projection neurons in AD. To allow quantitative assessment of axonal transport in vivo, we developed voxel-based statistical mapping technology as well as a tracer kinetic modeling method based on mass transport for manganese-enhanced MRI to estimate axonal transport rates in aging rats and AD transgenic mice. These techniques demonstrated manganese-enhanced signal changes in axonal projections of the olfactory tract and decreased axonal transport rates in rodent models of aging and AD. Altered axonal transport may be a critical pathophysiological process in aging and AD. Manganese-enhanced MRI provides exciting opportunities for the investigations of altered axonal transport in AD and related disorders. (orig.)

  11. Regeneration of motor axons in the rat sciatic nerve studied by labeling with axonally transported radioactive proteins

    International Nuclear Information System (INIS)

    Labeling regenerating axons with axonally transported radioactive proteins provides information about the location of the entire range of axons from the fastest growing ones to those which are trapped in the scar. This technique has been used to study the regeneration of motor axons in the rat sciatic nerve after a crush lesion. From 2 to 14 days after the crush the lumbar spinal cord was exposed by laminectomy and multiple injections of [3H]proline were made stereotactically in the ventral horn. Twenty-four hours later the nerves were removed and the distribution of radioactivity along the nerve was measured by liquid scintillation counting. There was a peak of radioactivity in the regenerating axons distal to the crush due to an accumulation of label in the tips of these axons. After a delay of 3.2 +- 0.2 (S.E.) days, this peak advanced down the nerve at a rate of 3.0 +- 0.1 (S.E.) mm/day. The leading edge of this peak, which marks the location of the endings of the most rapidly growing labeled fibers, moved down the nerve at a rate of 4.4 +- 0.2 mm/day after a delay of 2.1 +- 0.2 days; this is the same time course as that of the most rapidly regenerating sensory axons in the rat sciatic nerve, measured by the pinch test. Another peak of radioactivity at the crush site, presumed to represent the ends of unregenerated axons or misdirected sprouts, declined rapidly during the first week, and more slowly thereafter. (Auth.)

  12. Axonal Transport Proteomics Reveals Mobilization of Translation Machinery to the Lesion Site in Injured Sciatic Nerve*

    OpenAIRE

    Michaelevski, Izhak; Medzihradszky, Katalin F.; Lynn, Aenoch; Burlingame, Alma L.; Fainzilber, Mike

    2009-01-01

    Investigations of the molecular mechanisms underlying responses to nerve injury have highlighted the importance of axonal transport systems. To obtain a comprehensive view of the protein ensembles associated with axonal transport in injured axons, we analyzed the protein compositions of axoplasm concentrated at ligatures following crush injury of rat sciatic nerve. LC-MS/MS analyses of iTRAQ-labeled peptides from axoplasm distal and proximal to the ligation sites revealed protein ensembles tr...

  13. Axonal transport of proteoglycans to the goldfish optic tectum

    International Nuclear Information System (INIS)

    The study addressed the question of whether 35SO4 labeled molecules that have been delivered to the goldfish optic nerve terminals by rapid axonal transport include soluble proteoglycans. For analysis, tectal homogenates were subfractionated into a soluble fraction (soluble after centrifugation at 105,000 g), a lysis fraction (soluble after treatment with hypotonic buffer followed by centrifugation at 105,000 g) and a final 105,000 g pellet fraction. The soluble fraction contained 25.7% of incorporated radioactivity and upon DEAE chromatography was resolved into a fraction of sulfated glycoproteins eluting at 0-0.32 M NaCl and containing 39.5% of total soluble label and a fraction eluting at 0.32-0.60 M NaCl containing 53.9% of soluble label. This latter fraction was included on columns of Sepharose CL-6B with or without 4 M guanidine and after pronase digestion was found to have 51% of its radioactivity contained in the glycosaminoglycans (GAGs) heparan sulfate and chondroitin (4 or 6) sulfate in the ratio of 70% to 30%. Mobility of both intact proteoglycans and constituent GAGs on Sepharose CL-6B indicated a size distribution that is smaller than has been observed for proteoglycans and GAGs from cultured neuronal cell lines. Similar analysis of lysis fraction, containing 11.5% of incorporated 35SO4, showed a mixture of heparan sulfate and chondroitin sulfate containing proteoglycans, apparent free heparan sulfate and few, if any, sulfated glycoproteins. Overall, the results support the hypothesis that soluble proteoglycans are among the molecules axonally transported in the visual system

  14. DIRECT MEASUREMENT OF FAST AXONAL ORGANELLE TRANSPORT IN THE SCIATIC NERVE OF RATS TREATED WITH ACRYLAMIDE

    Science.gov (United States)

    The effects of acrylamide on fast axonal transport have been measured primarily using the indirect methods of isotope or enzyme accumulation. e report the first direct evaluation of the effects of sub-chronic acrylamide dosing (150, 300 or 500 mg/kg total dose) on the fast axonal...

  15. RETROGRADE AXONAL TRANSPORT OF PHOSPHOINOSITIDES AFTER INTRANEURAL INJECTION OF [3H]MYO-INOSITOL INTO THE RAT SCIATIC NERVE

    Science.gov (United States)

    Although autoradiography has demonstrated local incorporation of [3H]inositol into axonal phospholipids after intraneural injection (Gould, 1976; Gould et at., 1987b), retrograde axonal transport of phosphatidylinositol has only been demonstrated after injection of lipid precurso...

  16. In vivo axonal transport deficits in a mouse model of fronto-temporal dementia

    Directory of Open Access Journals (Sweden)

    Tabassum Majid

    2014-01-01

    Discussion: In our study, we identified the presence of age-dependent axonal transport deficits beginning at 3 months of age in rTg4510 mice. We correlated these deficits at 3 months to the presence of hyperphosphorylated tau in the brain and the presence within the olfactory epithelium. We observed tau pathology not only in the soma of these neurons but also within the axons and processes of these neurons. Our characterization of axonal transport in this tauopathy model provides a functional time point that can be used for future therapeutic interventions.

  17. Alterations in axonal transport motor proteins in sporadic and experimental Parkinson’s disease

    OpenAIRE

    Chu, Yaping; Morfini, Gerardo A.; Langhamer, Lori B.; He, Yinzhen; Brady, Scott T.; KORDOWER, JEFFREY H.

    2012-01-01

    The progressive loss of the nigrostriatal pathway is a distinguishing feature of Parkinson’s disease. As terminal field loss seems to precede cell body loss, we tested whether alterations of axonal transport motor proteins would be early features in Parkinson’s disease. There was a decline in axonal transport motor proteins in sporadic Parkinson’s disease that preceded other well-known nigral cell-related pathology such as phenotypic downregulation of dopamine. Reductions in conventional kine...

  18. Quantification of Retrograde Axonal Transport in the Rat Optic Nerve by Fluorogold Spectrometry

    OpenAIRE

    van Oterendorp, Christian; Sgouris, Stavros; Bach, Michael; Martin, Gottfried; Biermann, Julia; Jordan, Jens F.; Lagrèze, Wolf A

    2012-01-01

    Purpose Disturbed axonal transport is an important pathogenic factor in many neurodegenerative diseases, such as glaucoma, an eye disease characterised by progressive atrophy of the optic nerve. Quantification of retrograde axonal transport in the optic nerve usually requires labour intensive histochemical techniques or expensive equipment for in vivo imaging. Here, we report on a robust alternative method using Fluorogold (FG) as tracer, which is spectrometrically quantified in retinal tissu...

  19. Neurofilament subunit (NFL) head domain phosphorylation regulates axonal transport of neurofilaments.

    LENUS (Irish Health Repository)

    Yates, Darran M

    2009-04-01

    Neurofilaments are the intermediate filaments of neurons and are synthesised in neuronal cell bodies and then transported through axons. Neurofilament light chain (NFL) is a principal component of neurofilaments, and phosphorylation of NFL head domain is believed to regulate the assembly of neurofilaments. However, the role that NFL phosphorylation has on transport of neurofilaments is poorly understood. To address this issue, we monitored axonal transport of phosphorylation mutants of NFL. We mutated four known phosphorylation sites in NFL head domain to either preclude phosphorylation, or mimic permanent phosphorylation. Mutation to preclude phosphorylation had no effect on transport but mutation of three sites to mimic permanent phosphorylation inhibited transport. Mutation of all four sites together to mimic permanent phosphorylation proved especially potent at inhibiting transport and also disrupted neurofilament assembly. Our results suggest that NFL head domain phosphorylation is a regulator of neurofilament axonal transport.

  20. Axonal transport and incorporation of radioactivity after injection of N-[3H]acetyl-D-mannosamine into rat mesencephalon

    International Nuclear Information System (INIS)

    A study has been performed to demonstrate the possibility of incorporation of sialic acid into nerve endings of the rubrospinal tract after antegrade axonal transport. Young adult rats received injections of N-[3H]acetyl-D-mannosamine into the red nucleus and axonal transport of the tritiated compounds along the axons of afferent and efferent connections of the red nucleus was studied and the transported material was analysed. Light microscopic autoradiography and biochemical methods were used. (Auth./C.F.)

  1. Effects of p-xylene inhalation on axonal transport in the rat retinal ganglion cells

    International Nuclear Information System (INIS)

    Although the solvent xylene is suspected of producing nervous system dysfunction in animals and humans, little is known regarding the neurochemical consequences of xylene inhalation. The intent of this study was to determine the effect of intermittent, acute, and subchronic p-xylene exposure on the axonal transport of proteins and glycoproteins within the rat retinofugal tract. A number of different exposure regimens were tested ranging from 50 ppm for a single 6-hr exposure to 1600 ppm 6 hr/day, 5 days/week, for a total of 8 exposure days. Immediately following removal from the inhalation chambers rats were injected intraocularly with [35S]methionine and [3H]fucose (to label retinal proteins and glycoproteins, respectively) and the axonal transport of labeled macromolecules to axons (optic nerve and optic tract) and nerve endings (lateral geniculate body and superior colliculus) was examined 20 hr after precursor injection. Only relatively severe exposure regimens (i.e., 800 or 1600 ppm 6 hr/day, 5 days/week, for 1.5 weeks) produced significant reductions in axonal transport; there was a moderate reduction in the axonal transport of 35S-labeled proteins in the 800-ppm-treated group which was more widespread in the 1600 ppm-treated group. Transport of 3H-labeled glycoproteins was less affected. Assessment of retinal metabolism immediately after isotope injection indicated that the rate of precursor uptake was not reduced in either treatment group. Furthermore, rapid transport was still substantially reduced in animals exposed to 1600 ppm p-xylene and allowed a 13-day withdrawal period. These data indicate that p-xylene inhalation decreases rapid axonal transport supplied to the projections of the rat retinal ganglion cells immediately after cessation of inhalation exposure and that this decreased transport is still apparent 13 days after the last exposure

  2. Tri-partite complex for axonal transport drug delivery achieves pharmacological effect

    Directory of Open Access Journals (Sweden)

    Frederickson Martyn

    2010-01-01

    Full Text Available Abstract Background Targeted delivery of pharmaceutical agents into selected populations of CNS (Central Nervous System neurons is an extremely compelling goal. Currently, systemic methods are generally used for delivery of pain medications, anti-virals for treatment of dermatomal infections, anti-spasmodics, and neuroprotectants. Systemic side effects or undesirable effects on parts of the CNS that are not involved in the pathology limit efficacy and limit clinical utility for many classes of pharmaceuticals. Axonal transport from the periphery offers a possible selective route, but there has been little progress towards design of agents that can accomplish targeted delivery via this intraneural route. To achieve this goal, we developed a tripartite molecular construction concept involving an axonal transport facilitator molecule, a polymer linker, and a large number of drug molecules conjugated to the linker, then sought to evaluate its neurobiology and pharmacological behavior. Results We developed chemical synthesis methodologies for assembling these tripartite complexes using a variety of axonal transport facilitators including nerve growth factor, wheat germ agglutinin, and synthetic facilitators derived from phage display work. Loading of up to 100 drug molecules per complex was achieved. Conjugation methods were used that allowed the drugs to be released in active form inside the cell body after transport. Intramuscular and intradermal injection proved effective for introducing pharmacologically effective doses into selected populations of CNS neurons. Pharmacological efficacy with gabapentin in a paw withdrawal latency model revealed a ten fold increase in half life and a 300 fold decrease in necessary dose relative to systemic administration for gabapentin when the drug was delivered by axonal transport using the tripartite vehicle. Conclusion Specific targeting of selected subpopulations of CNS neurons for drug delivery by axonal

  3. Reduced axonal transport in Parkinson's disease cybrid neurites is restored by light therapy

    Directory of Open Access Journals (Sweden)

    De Taboada Luis

    2009-06-01

    Full Text Available Abstract Background It has been hypothesized that reduced axonal transport contributes to the degeneration of neuronal processes in Parkinson's disease (PD. Mitochondria supply the adenosine triphosphate (ATP needed to support axonal transport and contribute to many other cellular functions essential for the survival of neuronal cells. Furthermore, mitochondria in PD tissues are metabolically and functionally compromised. To address this hypothesis, we measured the velocity of mitochondrial movement in human transmitochondrial cybrid "cytoplasmic hybrid" neuronal cells bearing mitochondrial DNA from patients with sporadic PD and disease-free age-matched volunteer controls (CNT. The absorption of low level, near-infrared laser light by components of the mitochondrial electron transport chain (mtETC enhances mitochondrial metabolism, stimulates oxidative phosphorylation and improves redox capacity. PD and CNT cybrid neuronal cells were exposed to near-infrared laser light to determine if the velocity of mitochondrial movement can be restored by low level light therapy (LLLT. Axonal transport of labeled mitochondria was documented by time lapse microscopy in dopaminergic PD and CNT cybrid neuronal cells before and after illumination with an 810 nm diode laser (50 mW/cm2 for 40 seconds. Oxygen utilization and assembly of mtETC complexes were also determined. Results The velocity of mitochondrial movement in PD cybrid neuronal cells (0.175 +/- 0.005 SEM was significantly reduced (p Conclusion The results from this study support our proposal that axonal transport is reduced in sporadic PD and that a single, brief treatment with near-infrared light can restore axonal transport to control levels. These results are the first demonstration that LLLT can increase axonal transport in model human dopaminergic neuronal cells and they suggest that LLLT could be developed as a novel treatment to improve neuronal function in patients with PD.

  4. Improvement of cobalt-transport in axons by complexing agents.

    Science.gov (United States)

    Gallyas, F; Lénárd, L; Lázár, G

    1978-09-01

    The use of the cobalt technique is limited by the fact that cobaltous ions travel within axons for a shorter distance than do other intracellular markers. In the present experiments different organic cobaltous complexes were tested in the rat's sciatic nerve. Cobaltous complexes containing ornithine, threonine, lysine or Girard's reagent travelled two or three times further than did the cobaltous ions alone. Using the lysine complex in the frog's visual system, very fine terminals were observed which have never been demonstrated with other techniques. The possible use of other metal complexes as intracellular markers are also discussed. PMID:19605220

  5. Effect of MSH/ACTH peptides on fast axonal transport in intact and regenerating sciatic nerves

    International Nuclear Information System (INIS)

    Fast axonal transport was examined in intact rats treated with ACTH 4-10 or ACTH 4-9 (ORG 2766), hypophysectomized rats, adrenalectomized rats, and in ACTH 4-10 treated rats with crushed regenerating sciatic nerves by injecting 3H-leucine into the ventral horn region of the spinal cord. The distance traveled by the transported activity along the sciatic nerve and the rate of fast axonal transport were not significantly altered as a result of treatment with ACTH 4-10, ACTH 4-9 (ORG 2766), hypophysectomy, or adrenalectomy. Treatment with ACTH 4-9 (ORG 2766) at concentrations of 1 μg/Kg /day and 10 μg/Kg/day caused significant reductions (62% and 64% respectively) in the crest height of the fast axonal transport curve as compared to 0.9% saline treated control animals. No significant differences were found in comparing the distance, rate, slope, or crest height of ACTH 4-10 treated animals with crushed regenerating (7 or 14d) sciatic nerves to control animals. In the group of animals in days, the amount of radiolabeled activity was significantly increased in the ACTH 4-10 treated animals as compared to control animals. The results indicate that during regeneration the peptide acts to prolong the initially high levels of synthetic activity which occur in regenerating axons

  6. LOCALLY SYNTHESIZED PHOSPHATIDYCHOLINE, BUT NOT PROTEIN, UNDERGOES RAPID RETROGRADE AXONAL TRANSPORT IN THE RAT SCIATIC NERVE

    Science.gov (United States)

    Retrograde axonal transport of phosphatidylcholine (PC) in the sciatic nerve has been demonstrated only after injection of lipid precursors into the cell body regions (Armstrong et al. 1985). icroinjection of [methyl-3H]choline into the sciatic nerve results in extensive incorpor...

  7. Fast axonal transport of labeled proteins in motoneurons of exercise-trained rats

    International Nuclear Information System (INIS)

    In this study, the fast orthograde axonal transport of radiolabeled proteins was measured to determine the effects of endurance-running training on transport velocity and amounts of transported proteins in rat sciatic motoneurons. Female rats were subjected to a progressive running-training program for 10-12 wk. Twenty-four hours after the last training session, rats underwent right L4-L5 dorsal root ganglionectomy. The next day, 20 microCi of [3H]leucine was injected bilaterally in the vicinity of the motoneuronal cell bodies supplying the sciatic nerve, to study axonal transport parameters. Results showed that peak and average transport velocities of labeled proteins were significantly (P less than 0.05) increased by 22 and 29%, respectively, in the deafferented nerves of the runners as compared with controls. Moreover, the amount of total transported protein-bound radioactivity was increased in both left (40%) and right (37%) sciatic nerves of the runners. An exhaustive exercise session reduced (P less than 0.05) peak displacement (8%) and total transported protein-bound radioactivity (36%) in the sciatic nerves of control rats, whereas no changes were noticed in trained animals. The data suggest that chronic endurance running induces significant adaptations in the fast axonal transport of labeled proteins

  8. A comparative quantitative assessment of axonal and dendritic mRNA transport in maturing hippocampal neurons.

    Directory of Open Access Journals (Sweden)

    Gunja K Pathak

    Full Text Available Translation of mRNA in axons and dendrites enables a rapid supply of proteins to specific sites of localization within the neuron. Distinct mRNA-containing cargoes, including granules and mitochondrial mRNA, are transported within neuronal projections. The distributions of these cargoes appear to change during neuronal development, but details on the dynamics of mRNA transport during these transitions remain to be elucidated. For this study, we have developed imaging and image processing methods to quantify several transport parameters that can define the dynamics of RNA transport and localization. Using these methods, we characterized the transport of mitochondrial and non-mitochondrial mRNA in differentiated axons and dendrites of cultured hippocampal neurons varying in developmental maturity. Our results suggest differences in the transport profiles of mitochondrial and non-mitochondrial mRNA, and differences in transport parameters at different time points, and between axons and dendrites. Furthermore, within the non-mitochondrial mRNA pool, we observed two distinct populations that differed in their fluorescence intensity and velocity. The net axonal velocity of the brighter pool was highest at day 7 (0.002±0.001 µm/s, mean ± SEM, raising the possibility of a presynaptic requirement for mRNA during early stages of synapse formation. In contrast, the net dendritic velocity of the brighter pool increased steadily as neurons matured, with a significant difference between day 12 (0.0013±0.0006 µm/s and day 4 (-0.003±0.001 µm/s suggesting a postsynaptic role for mRNAs in more mature neurons. The dim population showed similar trends, though velocities were two orders of magnitude higher than of the bright particles. This study provides a baseline for further studies on mRNA transport, and has important implications for the regulation of neuronal plasticity during neuronal development and in response to neuronal injury.

  9. The myriad roles of Miro in the nervous system: axonal transport of mitochondria and beyond

    OpenAIRE

    Lee, Kyu-Sun; Lu, Bingwei

    2014-01-01

    Mitochondrial rho GTPase (Miro) is a mitochondrial outer membrane protein containing two GTPase domains and two helix-loop-helix Ca2+-binding domains called EF hands. Pioneering genetic studies in Drosophila first revealed a key function of Miro in regulating the axonal transport of mitochondria, during which Miro forms a multi-protein transport complex with Milton and Kinesin heavy chain (KHC) to link trafficking mitochondria with the microtubule (MT) cytoskeleton. Recent studies showed that...

  10. The Myriad Roles of Miro in the Nervous System: Axonal Transport of Mitochondria and Beyond

    OpenAIRE

    Bingwei Lu

    2014-01-01

    Mitochondrial rho GTPase (Miro) is a mitochondrial outer membrane protein containing two GTPase domains and two helix-loop-helix Ca2+-binding domains called EF hands. Pioneering genetic studies in Drosophila first revealed a key function of Miro in regulating the axonal transport of mitochondria, during which Miro forms a multi-protein transport complex with Milton and Kinesin heavy chain (KHC) to link trafficking mitochondria with the microtubule cytoskeleton. Recent studies showed that thro...

  11. Non-Cell-Autonomous Regulation of Retrograde Motoneuronal Axonal Transport in an SBMA Mouse Model

    Science.gov (United States)

    Halievski, Katherine; Kemp, Michael Q.; Breedlove, S. Marc; Miller, Kyle E.

    2016-01-01

    Abstract Defects in axonal transport are seen in motoneuronal diseases, but how that impairment comes about is not well understood. In spinal bulbar muscular atrophy (SBMA), a disorder linked to a CAG/polyglutamine repeat expansion in the androgen receptor (AR) gene, the disease-causing AR disrupts axonal transport by acting in both a cell-autonomous fashion in the motoneurons themselves, and in a non-cell-autonomous fashion in muscle. The non-cell-autonomous mechanism is suggested by data from a unique “myogenic” transgenic (TG) mouse model in which an AR transgene expressed exclusively in skeletal muscle fibers triggers an androgen-dependent SBMA phenotype, including defects in retrograde transport. However, motoneurons in this TG model retain the endogenous AR gene, leaving open the possibility that impairments in transport in this model also depend on ARs in the motoneurons themselves. To test whether non-cell-autonomous mechanisms alone can perturb retrograde transport, we generated male TG mice in which the endogenous AR allele has the testicular feminization mutation (Tfm) and, consequently, is nonfunctional. Males carrying the Tfm allele alone show no deficits in motor function or axonal transport, with or without testosterone treatment. However, when Tfm males carrying the myogenic transgene (Tfm/TG) are treated with testosterone, they develop impaired motor function and defects in retrograde transport, having fewer retrogradely labeled motoneurons and deficits in endosomal flux based on time-lapse video microscopy of living axons. These findings demonstrate that non-cell-autonomous disease mechanisms originating in muscle are sufficient to induce defects in retrograde transport in motoneurons. PMID:27517091

  12. Membrane turnover and receptor trafficking in regenerating axons.

    Science.gov (United States)

    Hausott, Barbara; Klimaschewski, Lars

    2016-02-01

    Peripheral axonal regeneration requires surface-expanding membrane addition. The continuous incorporation of new membranes into the axolemma allows the pushing force of elongating microtubules to drive axonal growth cones forwards. Hence, a constant supply of membranes and cytoskeletal building blocks is required, often for many weeks. In human peripheral nerves, axonal tips may be more than 1 m away from the neuronal cell body. Therefore, in the initial phase of regeneration, membranes are derived from pre-existing vesicles or synthesised locally. Only later stages of axonal regeneration are supported by membranes and proteins synthesised in neuronal cell bodies, considering that the fastest anterograde transport mechanisms deliver cargo at 20 cm/day. Whereas endocytosis and exocytosis of membrane vesicles are balanced in intact axons, membrane incorporation exceeds membrane retrieval during regeneration to compensate for the loss of membranes distal to the lesion site. Physiological membrane turnover rates will not be established before the completion of target reinnervation. In this review, the current knowledge on membrane traffic in axonal outgrowth is summarised, with a focus on endosomal vesicles as the providers of membranes and carriers of growth factor receptors required for initiating signalling pathways to promote the elongation and branching of regenerating axons in lesioned peripheral nerves. PMID:26222895

  13. 4S RNA is transported axonally in normal and regenerating axons of the sciatic nerves of rats

    International Nuclear Information System (INIS)

    Experiments were designed to determine if following injection of [3H]uridine into the lumbar spinal cord of the rat, [3H]RNA could be demonstrated within axons of the sciatic nerve, and if 4S RNA is the predominant predominant RNA species present in these axons. (Auth.)

  14. Assessment of retinal ganglion cell damage in glaucomatous optic neuropathy: Axon transport, injury and soma loss.

    Science.gov (United States)

    Nuschke, Andrea C; Farrell, Spring R; Levesque, Julie M; Chauhan, Balwantray C

    2015-12-01

    Glaucoma is a disease characterized by progressive axonal pathology and death of retinal ganglion cells (RGCs), which causes structural changes in the optic nerve head and irreversible vision loss. Several experimental models of glaucomatous optic neuropathy (GON) have been developed, primarily in non-human primates and, more recently and commonly, in rodents. These models provide important research tools to study the mechanisms underlying glaucomatous damage. Moreover, experimental GON provides the ability to quantify and monitor risk factors leading to RGC loss such as the level of intraocular pressure, axonal health and the RGC population. Using these experimental models we are able to gain a better understanding of GON, which allows for the development of potential neuroprotective strategies. Here we review the advantages and disadvantages of the relevant and most often utilized methods for evaluating axonal degeneration and RGC loss in GON. Axonal pathology in GON includes functional disruption of axonal transport (AT) and structural degeneration. Horseradish peroxidase (HRP), rhodamine-B-isothiocyanate (RITC) and cholera toxin-B (CTB) fluorescent conjugates have proven to be effective reporters of AT. Also, immunohistochemistry (IHC) for endogenous AT-associated proteins is often used as an indicator of AT function. Similarly, structural degeneration of axons in GON can be investigated via changes in the activity and expression of key axonal enzymes and structural proteins. Assessment of axonal degeneration can be measured by direct quantification of axons, qualitative grading, or a combination of both methods. RGC loss is the most frequently quantified variable in studies of experimental GON. Retrograde tracers can be used to quantify RGC populations in rodents via application to the superior colliculus (SC). In addition, in situ IHC for RGC-specific proteins is a common method of RGC quantification used in many studies. Recently, transgenic mouse models

  15. Pharmacological characterization of axonally transported (125I)-alpha-bungatoxin binding sites in rat sciatic nerve

    International Nuclear Information System (INIS)

    The authors attempt to label the putative receptors as they are axonally transported in peripheral nerves. With the use of an innovative autoradiographic technique, this approach as enabled the investigation of the pharmacological properties of the toxin-binding site interaction. The tissue sections from adult male rat sciatic nerves were incubated for 60 min at room temperature in phosphate buffer saline containing 2 nM I 125-alpha-BuTX with or without displacer. A bright field micrograph as well as dark field autoradiograph is illustrated of a ligated (12 hr.) rat sciatic nerve section incubated with I 125-alpha-BuTX. If one presumes that axonally transported I 125-alpha-BuTX binding sites correspond to receptors whose destination is the presynaptic membrane, then the data presented in this study may provide a pharmacological basis for differentiating pre- and postsynaptic sites of action of cholinergic drugs on the mammalian neuromuscular junction

  16. Axon Transport and Neuropathy: Relevant Perspectives on the Etiopathogenesis of Familial Dysautonomia.

    Science.gov (United States)

    Tourtellotte, Warren G

    2016-03-01

    Peripheral neuropathies are highly prevalent and are most often associated with chronic disease, side effects from chemotherapy, or toxic-metabolic abnormalities. Neuropathies are less commonly caused by genetic mutations, but studies of the normal function of mutated proteins have identified particular vulnerabilities that often implicate mitochondrial dynamics and axon transport mechanisms. Hereditary sensory and autonomic neuropathies are a group of phenotypically related diseases caused by monogenic mutations that primarily affect sympathetic and sensory neurons. Here, I review evidence to indicate that many genetic neuropathies are caused by abnormalities in axon transport. Moreover, in hereditary sensory and autonomic neuropathies. There may be specific convergence on gene mutations that disrupt nerve growth factor signaling, upon which sympathetic and sensory neurons critically depend. PMID:26724390

  17. Berberine Attenuates Axonal Transport Impairment and Axonopathy Induced by Calyculin A in N2a Cells

    OpenAIRE

    Xiaofeng Liu; Jie Zhou; Morad Dirhem Naji Abid; Huanhuan Yan; Hao Huang; Limin Wan; Zuohua Feng; Juan Chen

    2014-01-01

    Berberine is a primary component of the most functional extracts of Coptidis rhizome used in traditional Chinese medicine for centuries. Recent reports indicate that Berberine has the potential to prevent and treat Alzheimer's disease (AD). The previous studies reported that Calyculin A (CA) impaired the axonal transport in neuroblastoma-2a (N2a) cells. Berberine attenuated tau hyperphosphorylation and cytotoxicity induced by CA. Our study aimed at investigating the effects of Berberine on th...

  18. Analysis of axonal transport and molecular chaperones during neurodegeneration in drosophila

    OpenAIRE

    Sinadinos, Christopher

    2010-01-01

    Neuronal dysfunction and cell death occurs during neurodegeneration. Animal models that express human disease genes and show neurodegenerative-like pathologies are widely used to study particular molecular systems in early neurodegenerative changes. Axonal transport (AT) is perturbed in several prevalent neurodegenerative diseases. The development of a Huntington’s Disease (HD) model in Drosophila melanogaster larvae is described, in which disease gene expression is directed to motor neurons ...

  19. Release of axonally transported material from an in vitro amphibian sciatic nerve preparation

    International Nuclear Information System (INIS)

    The rapid axonal transport of a pulse of [35S]methionine-labelled material was used to study the release of transported material from amphibian nerve maintained in vitro. Following creation of a moving pulse of activity in a dorsal root ganglion-sciatic nerve preparation, the ganglion was removed and the nerve placed in a three-compartment tray, the section of nerve in the middle compartment containing no truncated branches (unbranched section). All three compartments were filled with a saline solution that in some studies contained nonradioactive methionine (1.0 mmol/L). Analysis of studies in which nonradioactive methionine was absent revealed that labelled material appeared in the bathing solution of the end compartments that contained truncated branches, but not in the solution of the middle (unbranched) compartment. The quantity of label released in the branched compartments was approximately 6% of that remaining in the corresponding section of nerve following an 18-20 h incubation period. However, when nonradioactive methionine was present, all compartments showed an additional activity in the bathing solution of approximately 10% of that remaining in the nerve. In another study in which a position-sensitive detector of ionizing radiation was used to monitor progress of the pulse, it was found that activity did not enter the bathing solution of a compartment prior to the pulse of activity. It is concluded that in the absence of methionine from the bathing solution, axonally transported material is released only from regions of nerve that contain severed axons; however, the presence of methionine allows transported material to be released from nerve containing intact axons. Ultrafiltration studies and thin-layer chromatography revealed the majority of material released to be of low-molecular weight (less than 30,000 daltons) and not free [35S]methionine

  20. Quantification of retrograde axonal transport in the rat optic nerve by fluorogold spectrometry.

    Directory of Open Access Journals (Sweden)

    Christian van Oterendorp

    Full Text Available PURPOSE: Disturbed axonal transport is an important pathogenic factor in many neurodegenerative diseases, such as glaucoma, an eye disease characterised by progressive atrophy of the optic nerve. Quantification of retrograde axonal transport in the optic nerve usually requires labour intensive histochemical techniques or expensive equipment for in vivo imaging. Here, we report on a robust alternative method using Fluorogold (FG as tracer, which is spectrometrically quantified in retinal tissue lysate. METHODS: To determine parameters reflecting the relative FG content of a sample FG was dissolved in retinal lysates at different concentrations and spectra were obtained. For validation in vivo FG was injected uni- or bilaterally into the superior colliculus (SC of Sprague Dawley rats. The retinal lysate was analysed after 3, 5 and 7 days to determine the time course of FG accumulation in the retina (n = 15. In subsequent experiments axona transport was impaired by optic nerve crush (n = 3, laser-induced ocular hypertension (n = 5 or colchicine treatment to the SC (n = 10. RESULTS: Spectrometry at 370 nm excitation revealed two emission peaks at 430 and 610 nm. We devised a formula to calculate the relative FG content (c(FG, from the emission spectrum. c(FG is proportional to the real FG concentration as it corrects for variations of retinal protein concentration in the lysate. After SC injection, c(FG monotonously increases with time (p = 0.002. Optic nerve axonal damage caused a significant decrease of c(FG (crush p = 0.029; hypertension p = 0.025; colchicine p = 0.006. Lysates are amenable to subsequent protein analysis. CONCLUSIONS: Spectrometrical FG detection in retinal lysates allows for quantitative assessment of retrograde axonal transport using standard laboratory equipment. It is faster than histochemical techniques and may also complement morphological in vivo analyses.

  1. Demyelination induces transport of ribosome-containing vesicles from glia to axons: evidence from animal models and MS patient brains.

    Science.gov (United States)

    Shakhbazau, Antos; Schenk, Geert J; Hay, Curtis; Kawasoe, Jean; Klaver, Roel; Yong, V Wee; Geurts, Jeroen J G; van Minnen, Jan

    2016-06-01

    Glial cells were previously proven capable of trafficking polyribosomes to injured axons. However, the occurrence of such transfer in the general pathological context, such as demyelination-related diseases, needs further evidence. Since this may be a yet unidentified universal contributor to axonal survival, we study putative glia-axonal ribosome transport in response to demyelination in animal models and patients in both peripheral and central nervous system. In the PNS we investigate whether demyelination in a rodent model has the potential to induce ribosome transfer. We also probe the glia-axonal ribosome supply by implantation of transgenic Schwann cells engineered to produce fluorescent ribosomes in the same demyelination model. We furthermore examine the presence of axonal ribosomes in mouse experimental autoimmune encephalomyelitis (EAE), a well-established model for multiple sclerosis (MS), and in human MS autopsy brain material. We provide evidence for increased axonal ribosome content in a pharmacologically demyelinated sciatic nerve, and demonstrate that at least part of these ribosomes originate in the transgenic Schwann cells. In the CNS one of the hallmarks of MS is demyelination, which is associated with severe disruption of oligodendrocyte-axon interaction. Here, we provide evidence that axons from spinal cords of EAE mice, and in the MS human brain contain an elevated amount of axonal ribosomes compared to controls. Our data provide evidence that increased axonal ribosome content in pathological axons is at least partly due to glia-to-axon transfer of ribosomes, and that demyelination in the PNS and in the CNS is one of the triggers capable to initiate this process. PMID:27115494

  2. Speciifc effects of c-Jun NH2-terminal kinase-interacting protein 1 in neuronal axons

    Institute of Scientific and Technical Information of China (English)

    Shu Tang; Qiang Wen; Xiao-jian Zhang; Quan-cheng Kan

    2016-01-01

    c-Jun NH2-terminal kinase (JNK)-interacting protein 3 plays an important role in brain-derived neurotrophic factor/tropomyosin-related kinase B (TrkB) anterograde axonal transport. It remains unclear whether JNK-interacting protein 1 mediates similar effects, or whether JNK-interacting protein 1 affects the regulation of TrkB anterograde axonal transport. In this study, we isolated rat embryonic hippocampus and cultured hippocampal neuronsin vitro. Coimmunoprecipitation results demonstrated that JNK-interacting protein 1 formed TrkB com-plexesin vitro andin vivo. Immunocytochemistry results showed that when JNK-interacting protein 1 was highly expressed, the distribution of TrkB gradually increased in axon terminals. However, the distribution of TrkB reduced in axon terminals after knocking out JNK-interact-ing protein 1. In addition, there were differences in distribution of TrkB after JNK-interacting protein 1 was knocked out compared with not. However, knockout of JNK-interacting protein 1 did not affect the distribution of TrkB in dendrites. These ifndings conifrm that JNK-inter-acting protein 1 can interact with TrkB in neuronal cells, and can regulate the transport of TrkB in axons, but not in dendrites.

  3. Axonal Transport and Neurodegeneration: How Marine Drugs Can Be Used for the Development of Therapeutics

    Science.gov (United States)

    White, Joseph A.; Banerjee, Rupkatha; Gunawardena, Shermali

    2016-01-01

    Unlike virtually any other cells in the human body, neurons are tasked with the unique problem of transporting important factors from sites of synthesis at the cell bodies, across enormous distances, along narrow-caliber projections, to distally located nerve terminals in order to maintain cell viability. As a result, axonal transport is a highly regulated process whereby necessary cargoes of all types are packaged and shipped from one end of the neuron to the other. Interruptions in this finely tuned transport have been linked to many neurodegenerative disorders including Alzheimer’s (AD), Huntington’s disease (HD), and amyotrophic lateral sclerosis (ALS) suggesting that this pathway is likely perturbed early in disease progression. Therefore, developing therapeutics targeted at modifying transport defects could potentially avert disease progression. In this review, we examine a variety of potential compounds identified from marine aquatic species that affect the axonal transport pathway. These compounds have been shown to function in microtubule (MT) assembly and maintenance, motor protein control, and in the regulation of protein degradation pathways, such as the autophagy-lysosome processes, which are defective in many degenerative diseases. Therefore, marine compounds have great potential in developing effective treatment strategies aimed at early defects which, over time, will restore transport and prevent cell death. PMID:27213408

  4. Miro, MCU, and calcium: bridging our understanding of mitochondrial movement in axons

    Directory of Open Access Journals (Sweden)

    Karen Chang

    2013-09-01

    Full Text Available Neurons are extremely polarized structures with long axons and dendrites, which require proper distribution of mitochondria and maintenance of mitochondrial dynamics for neuronal functions and survival. Indeed, recent studies show that various neurological disorders are linked to mitochondrial transport in neurons. Mitochondrial anterograde transport is believed to deliver metabolic energy to synaptic terminals where energy demands are high, while mitochondrial retrograde transport is required to repair or remove damaged mitochondria in axons. It has been suggested that Ca2+ plays a key role in regulating mitochondrial transport by altering the configuration of mitochondrial protein, miro. However, molecular mechanisms that regulate mitochondrial transport in neurons still are not well characterized. In this review, we will discuss the roles of miro in mitochondrial transport and how the recently identified components of the mitochondrial calcium uniporter add to our current model of mitochondrial mobility regulation.

  5. Riluzole protects against glutamate-induced slowing of neurofilament axonal transport.

    LENUS (Irish Health Repository)

    Stevenson, Alison

    2009-04-24

    Riluzole is the only drug approved for the treatment of amyotrophic lateral sclerosis (ALS) but its precise mode of action is not properly understood. Damage to axonal transport of neurofilaments is believed to be part of the pathogenic mechanism in ALS and this has been linked to defective glutamate handling and increased phosphorylation of neurofilament side-arm domains. Here, we show that riluzole protects against glutamate-induced slowing of neurofilament transport. Protection is associated with decreased neurofilament side-arm phosphorylation and inhibition of the activities of two neurofilament kinases, ERK and p38 that are activated in ALS. Thus, the anti-glutamatergic properties of riluzole include protection against glutamate-induced changes to neurofilament phosphorylation and transport.

  6. Axonal transport of cadmium in the olfactory nerve of the pike

    International Nuclear Information System (INIS)

    109Cd2+ was applied in the olfactory chambers of pikes (Esox lucius) and the dynamics of the axoplasmic flow of the metal was determined in the olfactory nerves by gamma spectrometry and autoradiography. The results showed that the 109Cd2+ is transported at a constant rate along the olfactory nerves. The profile of the 109Cd2+ in the nerves showed a wave front of transported metal followed by a saddle region. When the nasal chambers were washed 2 hr after application of the 109Cd2+ well-defined transport peaks for the metal were seen in the olfactory axons. The maximal velocity for the transport of 109Cd2+, which corresponds to the movement of the wave front, was 2.38±0.10 mm/hr (mean±S.E.) at the experimental temperature (10 deg. C). The average velocity for the transport of the 109Cd2+, which corresponds to the peak apex movement of the wave, was 2.18±0.05 mm/hr (mean ±S.E.) at 10 deg. C. The tranported 109Cd2+ was strongly accumulated in the anterior parts of the olfactory bulbs, whereas in other brain areas the levels of the metal remained low. Autoradiography of a pike exposed to 109Cd2+ via the water showed a strong labelling in the receptor-cell-containing olfactory rosettes, whereas other structures in the olfactory chambers were only weakly labelled. The accumulation and axonal transport in the olfactory neurons may be noxious and constitute an important component in the toxicology of cadmium in fish, and this may apply also to some other heavy metals. (author)

  7. The Myriad Roles of Miro in the Nervous System: Axonal Transport of Mitochondria and Beyond

    Directory of Open Access Journals (Sweden)

    Bingwei Lu

    2014-10-01

    Full Text Available Mitochondrial rho GTPase (Miro is a mitochondrial outer membrane protein containing two GTPase domains and two helix-loop-helix Ca2+-binding domains called EF hands. Pioneering genetic studies in Drosophila first revealed a key function of Miro in regulating the axonal transport of mitochondria, during which Miro forms a multi-protein transport complex with Milton and Kinesin heavy chain (KHC to link trafficking mitochondria with the microtubule cytoskeleton. Recent studies showed that through binding to the EF hands of Miro and causing conformational changes of Miro and alteration of protein-protein interactions within the transport complex, Ca2+ can alter the engagement of mitochondria with the microtubule (MT/kinesin network, offering one mechanism to match mitochondrial distribution with neuronal activity. Despite the importance of the Miro/Milton/Kinesin complex in regulating mitochondrial transport in metazoans, not all components of the transport complex are conserved in lower organisms, and transport-independent functions of Miro are emerging. Here we review the diverse functions of the evolutionarily conserved Miro proteins that are relevant to the development, maintenance, and functioning of the nervous system and discuss the potential contribution of Miro dysfunction to the pathogenesis of diseases of the nervous system.

  8. Quantitative measurements and modeling of cargo–motor interactions during fast transport in the living axon

    International Nuclear Information System (INIS)

    The kinesins have long been known to drive microtubule-based transport of sub-cellular components, yet the mechanisms of their attachment to cargo remain a mystery. Several different cargo-receptors have been proposed based on their in vitro binding affinities to kinesin-1. Only two of these—phosphatidyl inositol, a negatively charged lipid, and the carboxyl terminus of the amyloid precursor protein (APP-C), a trans-membrane protein—have been reported to mediate motility in living systems. A major question is how these many different cargo, receptors and motors interact to produce the complex choreography of vesicular transport within living cells. Here we describe an experimental assay that identifies cargo–motor receptors by their ability to recruit active motors and drive transport of exogenous cargo towards the synapse in living axons. Cargo is engineered by derivatizing the surface of polystyrene fluorescent nanospheres (100 nm diameter) with charged residues or with synthetic peptides derived from candidate motor receptor proteins, all designed to display a terminal COOH group. After injection into the squid giant axon, particle movements are imaged by laser-scanning confocal time-lapse microscopy. In this report we compare the motility of negatively charged beads with APP-C beads in the presence of glycine-conjugated non-motile beads using new strategies to measure bead movements. The ensuing quantitative analysis of time-lapse digital sequences reveals detailed information about bead movements: instantaneous and maximum velocities, run lengths, pause frequencies and pause durations. These measurements provide parameters for a mathematical model that predicts the spatiotemporal evolution of distribution of the two different types of bead cargo in the axon. The results reveal that negatively charged beads differ from APP-C beads in velocity and dispersion, and predict that at long time points APP-C will achieve greater progress towards the presynaptic

  9. A hereditary spastic paraplegia mutation in kinesin-1A/KIF5A disrupts neurofilament transport

    Directory of Open Access Journals (Sweden)

    Brown Anthony

    2010-11-01

    Full Text Available Abstract Background Hereditary spastic paraplegias are a group of neurological disorders characterized by progressive distal degeneration of the longest ascending and descending axons in the spinal cord, leading to lower limb spasticity and weakness. One of the dominantly inherited forms of this disease (spastic gait type 10, or SPG10 is caused by point mutations in kinesin-1A (also known as KIF5A, which is thought to be an anterograde motor for neurofilaments. Results We investigated the effect of an SPG10 mutation in kinesin-1A (N256S-kinesin-1A on neurofilament transport in cultured mouse cortical neurons using live-cell fluorescent imaging. N256S-kinesin-1A decreased both anterograde and retrograde neurofilament transport flux by decreasing the frequency of anterograde and retrograde movements. Anterograde velocity was not affected, whereas retrograde velocity actually increased. Conclusions These data reveal subtle complexities to the functional interdependence of the anterograde and retrograde neurofilament motors and they also raise the possibility that anterograde and retrograde neurofilament transport may be disrupted in patients with SPG10.

  10. Acrylamide Retards the Slow Axonal Transport of Neurofilaments in Rat Cultured Dorsal Root Ganglia Neurons and the Corresponding Mechanisms.

    Science.gov (United States)

    An, Lihong; Li, Guozhen; Si, Jiliang; Zhang, Cuili; Han, Xiaoying; Wang, Shuo; Jiang, Lulu; Xie, Keqin

    2016-05-01

    Chronic acrylamide (ACR) exposure induces peripheral-central axonopathy in occupational workers and laboratory animals, but the underlying mechanisms remain unclear. In this study, we first investigated the effects of ACR on slow axonal transport of neurofilaments in cultured rat dorsal root ganglia (DRG) neurons through live-cell imaging approach. Then for the underlying mechanisms exploration, the protein level of neurofilament subunits, motor proteins kinesin and dynein, and dynamitin subunit of dynactin in DRG neurons were assessed by western blotting and the concentrations of ATP was detected using ATP Assay Kit. The results showed that ACR treatment results in a dose-dependent decrease of slow axonal transport of neurofilaments. Furthermore, ACR intoxication significantly increases the protein levels of the three neurofilament subunits (NF-L, NF-M, NF-H), kinesin, dynein, and dynamitin subunit of dynactin in DRG neurons. In addition, ATP level decreased significantly in ACR-treated DRG neurons. Our findings indicate that ACR exposure retards slow axonal transport of NF-M, and suggest that the increase of neurofilament cargoes, motor proteins, dynamitin of dynactin, and the inadequate ATP supply contribute to the ACR-induced retardation of slow axonal transport. PMID:26721510

  11. EFFECTS OF HYPOTHERMIA ON THE IN VIVO MEASUREMENT OF RAPID AXONAL TRANSPORT IN THE RAT: A CAUTIONARY NOTE

    Science.gov (United States)

    Rapid axonal transport of glycoproteins was examined in the retinofugal projections of hypothermic and normothermic adult male Long-Evans hooded rats previously receiving intraocular injections of (3H)fucose. The amount of retinal fucosylation appeared normal in the hypothermic a...

  12. Axonal transport of rubidium and thallium in the olfactory nerve of mice

    International Nuclear Information System (INIS)

    Following intranasal administration of radioactive 86Rb+ and 201Tl+ in mice, we observed this direct transport via the olfactory nerve pathway. The 86RbCl and 201TlCl solutions were administered to two groups of mice, the unilateral intranasal and intravenous administration groups. After sacrifice, their heads were divided into the right and left side, which were then subdivided into seven parts; the nasal mucosa and brain regions were separated. Following the unilateral intranasal administration, uptake after 6 h by the olfactory bulb was significantly higher on the ipsilateral side (86Rb, 0.7 %dose; 201Tl, 0.5 %dose) than on the contralateral side (86Rb, 0.08 %dose; 201Tl, 0.15 %dose). Moreover, the 86Rb and 201Tl that accumulated in the olfactory bulb were gradually transported to other brain regions of the olfactory tract, the telencephalon and the diencephalon on the side corresponding to the nostril used for administration. Significant differences were observed between the right and left side of the brain regions 6 and 12 h after administration. Further, 201Tl autoradiography clearly showed striped patterns of dense accumulation, localized in the region around the glomerular layer and granule cell layer of the olfactory bulb and around the olfactory cortex. These results provide clear evidence of axonal transport via the olfactory nerve pathway, from nasal cavity to the olfactory bulb, as well as to the olfactory cortex through the synaptic junctions. The olfactory transport of the 86Rb+ and 201Tl+ is thought to represent the behavior of K+ in the olfactory system

  13. Increased slow transport in axons of regenerating newt limbs after a nerve conditioning lesion made prior to amputation

    International Nuclear Information System (INIS)

    The first part of this study shows that axonal density is constant in the limb stump of the next proximal to the area of traumatic nerve degeneration caused by limb amputation. The results of the second part of this work reveal that a nerve conditioning lesion made two weeks prior to amputation is associated with accelerated limb regeneration and that this accelerated limb regeneration is accompanied by an earlier arrival of axons. This is the first demonstration of naturally occurring limb regeneration being enhanced. In this study SCb cytoskeletal proteins were identified and measured using SDS-PAGE and liquid scintillation counting. Proteins were measured at 7, 14, 21, and 28 days after 35S-methionine injection and the normal rate of SCb transport determined to be 0.19 mm/day. A single axotomy does not enhance the rate of SCb transport but does increase the amount of labeled SCb proteins that are transported. When a conditioning lesion is employed prior to limb amputation and SCb proteins are measured at 7, 14, and 21 days after injection, there is a twofold acceleration in the rate of SCb transport and an increase in the amount of SCb proteins transported in conditioned axons

  14. Endosome-mediated retrograde axonal transport of P2X3 receptor signals in primary sensory neurons

    Institute of Scientific and Technical Information of China (English)

    Xu-Qiao Chen; BinWang; Chengbiao Wu; Jin Pan; Bo Yuan; Yuan-Yuan Su; Xing-Yu Jiang; Xu Zhang; Lan Bao

    2012-01-01

    Neurotrophins and their receptors adopt signaling endosomes to transmit retrograde signals.However,the mechanisms of retrograde signaling for other ligand/receptor systems are poorly understood.Here,we report that the signals of the purinergic (P)2X3 receptor,an ATP-gated ion channel are retrogradely transported in dorsal root ganglion (DRG) neuron axons.We found that Rab5,a small GTPase,controls the early sorting of P2X3 receptors into endosomes,while Rab7 mediates the fast retrograde transport of P2X3 receptors.Intraplantar injection and axonal application into the microfluidic chamber of α,β-methylene-ATP (α,β-MeATP),a P2X selective agonist,enhanced the endocytosis and retrograde transport of P2X3 receptors.The α,β-MeATP-induced Ca2+ influx activated a pathway comprised of protein kinase C,rat sarcoma viral oncogene and extracellular signal-regulated protein kinase (ERK),which associated with endocytic P2X3 receptors to form signaling endosomes.Disruption of the lipid rafts abolished the α,β-MeATP-induced ERK phosphorylation,endocytosis and retrograde transport of P2X3 receptors.Furthermore,treatment of peripheral axons with α,β-MeATP increased the activation level of ERK and cAMP response element-binding protein in the cell bodies of DRG neurons and enhanced neuronal excitability.Impairment of either microtubule-based axonal transport in vivo or dynein function in vitro blocked α,β-MeATP-induced retrograde signals.These results indicate that P2X3 receptor-activated signals are transmitted via retrogradely transported endosomes in primary sensory neurons and provide a novel signaling mechanism for ligand-gated channels.

  15. BODY TEMPERATURE-DEPENDENT AND INDEPENDENT ACTIONS OF CHLORDIMEFORM ON VISUAL EVOKED POTENTIALS AND AXONAL TRANSPORT IN OPTIC SYSTEM OF RAT

    Science.gov (United States)

    Pattern reversal evoked potentials (PREPs), flash evoked potentials (FEPs), optic nerve axonal transport, and body temperature were measured in hooded rats treated with either saline or the formamidine insecticide/acaricide, chlordimeform (CDM). Rats receiving CDM had low body te...

  16. Difference in trafficking of brain-derived neurotrophic factor between axons and dendrites of cortical neurons, revealed by live-cell imaging

    Directory of Open Access Journals (Sweden)

    Kohara Keigo

    2005-06-01

    Full Text Available Abstract Background Brain-derived neurotrophic factor (BDNF, which is sorted into a regulated secretory pathway of neurons, is supposed to act retrogradely through dendrites on presynaptic neurons or anterogradely through axons on postsynaptic neurons. Depending on which is the case, the pattern and direction of trafficking of BDNF in dendrites and axons are expected to be different. To address this issue, we analyzed movements of green fluorescent protein (GFP-tagged BDNF in axons and dendrites of living cortical neurons by time-lapse imaging. In part of the experiments, the expression of BDNF tagged with cyan fluorescent protein (CFP was compared with that of nerve growth factor (NGF tagged with yellow fluorescent protein (YFP, to see whether fluorescent protein-tagged BDNF is expressed in a manner specific to this neurotrophin. Results We found that BDNF tagged with GFP or CFP was expressed in a punctated manner in dendrites and axons in about two-thirds of neurons into which plasmid cDNAs had been injected, while NGF tagged with GFP or YFP was diffusely expressed even in dendrites in about 70% of the plasmid-injected neurons. In neurons in which BDNF-GFP was expressed as vesicular puncta in axons, 59 and 23% of the puncta were moving rapidly in the anterograde and retrograde directions, respectively. On the other hand, 64% of BDNF-GFP puncta in dendrites did not move at all or fluttered back and forth within a short distance. The rest of the puncta in dendrites were moving relatively smoothly in either direction, but their mean velocity of transport, 0.47 ± 0.23 (SD μm/s, was slower than that of the moving puncta in axons (0.73 ± 0.26 μm/s. Conclusion The present results show that the pattern and velocity of the trafficking of fluorescence protein-tagged BDNF are different between axons and dendrites, and suggest that the anterograde transport in axons may be the dominant stream of BDNF to release sites.

  17. The RNA binding and transport proteins staufen and fragile X mental retardation protein are expressed by rat primary afferent neurons and localize to peripheral and central axons.

    Science.gov (United States)

    Price, T J; Flores, C M; Cervero, F; Hargreaves, K M

    2006-09-15

    Neuronal proteins have been traditionally viewed as being derived solely from the soma; however, accumulating evidence indicates that dendritic and axonal sites are capable of a more autonomous role in terms of new protein synthesis. Such extra-somal translation allows for more rapid, on-demand regulation of neuronal structure and function than would otherwise be possible. While mechanisms of dendritic RNA transport have been elucidated, it remains unclear how RNA is trafficked into the axon for this purpose. Primary afferent neurons of the dorsal root (DRG) and trigeminal (TG) ganglia have among the longest axons in the neuraxis and such axonal protein synthesis would be advantageous, given the greater time involved for protein trafficking to occur via axonal transport. Therefore, we hypothesized that these primary sensory neurons might express proteins involved in RNA transport. Rat DRG and TG neurons expressed staufen (stau) 1 and 2 (detected at the mRNA level) and stau2 and fragile x mental retardation protein (FMRP; detected at the protein level). Stau2 mRNA was also detected in human TG neurons. Stau2 and FMRP protein were localized to the sciatic nerve and dorsal roots by immunohistochemistry and to dorsal roots by Western blot. Stau2 and FMRP immunoreactivities colocalized with transient receptor potential channel type 1 immunoreactivity in sensory axons of the sciatic nerve and dorsal root, suggesting that these proteins are being transported into the peripheral and central terminals of nociceptive sensory axons. Based on these findings, we propose that stau2 and FMRP proteins are attractive candidates to subserve RNA transport in sensory neurons, linking somal transcriptional events to axonal translation. PMID:16809002

  18. Concentration dependence of rapid axonal transport: a study of the transport kinetics of [35S]methionine-labeled protein in postganglionic sympathetic fibers of the bullfrog

    International Nuclear Information System (INIS)

    The kinetics of transport of radiolabeled proteins in sympathetic axons of the bullfrog sciatic nerve were examined after injection of [35S]methionine into the S9 sympathetic ganglion. Under resting conditions at 20 degrees C, the fastest moving material was carried distally at 5.7 +/- 0.3 mm/hr. Various manipulations of temperature in the proximal part of the nerve were used to alter the amount of protein transported into the distal region, which was always kept at 20 degrees C. The velocity in this test region was found to increase to over 9 mm/hr when material that had accumulated at a cold block for 4 hr was released by rewarming. This acceleration was transient, and base line velocity was regained after 2 hr. In order to increase the local concentration of transported protein by a second method, the proximal part of several nerves was warmed to 28 degrees C. Maximal transport velocity in the 20 degrees C test region rose to 6.2 +/- 0.12 mm/hr. To decrease the local concentration of transported protein, the proximal part of other nerves was cooled to 15 degrees C. Maximal transport velocity in the 20 degrees C test region fell to 4.7 +/- 0.7 mm/hr. We conclude that there is a small but real tendency for the velocity of rapid axonal transport in this neural system to be positively related to the availability of material suitable for transport

  19. Anterograde episodic memory in Korsakoff syndrome.

    Science.gov (United States)

    Fama, Rosemary; Pitel, Anne-Lise; Sullivan, Edith V

    2012-06-01

    A profound anterograde memory deficit for information, regardless of the nature of the material, is the hallmark of Korsakoff syndrome, an amnesic condition resulting from severe thiamine (vitamin B1) deficiency. Since the late nineteenth century when the Russian physician, S. S. Korsakoff, initially described this syndrome associated with "polyneuropathy," the observed global amnesia has been a primary focus of neuroscience and neuropsychology. In this review we highlight the historical studies that examined anterograde episodic memory processes in KS, present a timeline and evidence supporting the myriad theories proffered to account for this memory dysfunction, and summarize what is known about the neuroanatomical correlates and neural systems presumed affected in KS. Rigorous study of KS amnesia and associated memory disorders of other etiologies provide evidence for distinct mnemonic component processes and neural networks imperative for normal declarative and nondeclarative memory abilities and for mnemonic processes spared in KS, from whence emerged the appreciation that memory is not a unitary function. Debate continues regarding the qualitative and quantitative differences between KS and other amnesias and what brain regions and neural pathways are necessary and sufficient to produce KS amnesia. PMID:22644546

  20. Outsourcing CREB translation to axons to survive

    OpenAIRE

    Lin, Andrew C; Holt, Christine E.

    2008-01-01

    Nerve growth factor induces sensory neuron survival via retrograde signalling from the axon to the cell body. Local translation of the transcription factor CREB in the axon, followed by its transport to the nucleus, is involved in this process.

  1. NDE1 and GSK3β Associate with TRAK1 and Regulate Axonal Mitochondrial Motility: Identification of Cyclic AMP as a Novel Modulator of Axonal Mitochondrial Trafficking.

    Science.gov (United States)

    Ogawa, Fumiaki; Murphy, Laura C; Malavasi, Elise L V; O'Sullivan, Shane T; Torrance, Helen S; Porteous, David J; Millar, J Kirsty

    2016-05-18

    Mitochondria are essential for neuronal function, providing the energy required to power neurotransmission, and fulfilling many important additional roles. In neurons, mitochondria must be efficiently transported to sites, including synapses, where their functions are required. Neurons, with their highly elongated morphology, are consequently extremely sensitive to defective mitochondrial trafficking which can lead to neuronal ill-health/death. We recently demonstrated that DISC1 associates with mitochondrial trafficking complexes where it associates with the core kinesin and dynein adaptor molecule TRAK1. We now show that the DISC1 interactors NDE1 and GSK3β also associate robustly with TRAK1 and demonstrate that NDE1 promotes retrograde axonal mitochondrial movement. GSK3β is known to modulate axonal mitochondrial motility, although reports of its actual effect are conflicting. We show that, in our system, GSK3β promotes anterograde mitochondrial transport. Finally, we investigated the influence of cAMP elevation upon mitochondrial motility, and found a striking increase in mitochondrial motility and retrograde movement. DISC1, NDE1, and GSK3β are implicated as risk factors for major mental illness. Our demonstration that they function together within mitochondrial trafficking complexes suggests that defective mitochondrial transport may be a contributory disease mechanism in some cases of psychiatric disorder. PMID:26815013

  2. Rabies virus glycoprotein pseudotyping of lentiviral vectors enables retrograde axonal transport and access to the nervous system after peripheral delivery.

    Science.gov (United States)

    Mazarakis, N D; Azzouz, M; Rohll, J B; Ellard, F M; Wilkes, F J; Olsen, A L; Carter, E E; Barber, R D; Baban, D F; Kingsman, S M; Kingsman, A J; O'Malley, K; Mitrophanous, K A

    2001-09-15

    In this report it is demonstrated for the first time that rabies-G envelope of the rabies virus is sufficient to confer retrograde axonal transport to a heterologous virus/vector. After delivery of rabies-G pseudotyped equine infectious anaemia virus (EIAV) based vectors encoding a marker gene to the rat striatum, neurons in regions distal from but projecting to the injection site, such as the dopaminergic neurons of the substantia nigra pars compacta, become transduced. This retrograde transport to appropriate distal neurons was also demonstrated after delivery to substantia nigra, hippocampus and spinal cord and did not occur when vesicular stomatitis virus glycoprotein (VSV-G) pseudotyped vectors were delivered to these sites. In addition, peripheral administration of rabies-G pseudotyped vectors to the rat gastrocnemius muscle leads to gene transfer in motoneurons of lumbar spinal cord. In contrast the same vector pseudotyped with VSV-G transduced muscle cells surrounding the injection site, but did not result in expression in any cells in the spinal cord. Long-term expression was observed after gene transfer in the nervous system and a minimal immune response which, together with the possibility of non-invasive administration, greatly extends the utility of lentiviral vectors for gene therapy of human neurological disease. PMID:11590128

  3. Axon Degeneration Gated by Retrograde Activation of Somatic Pro-apoptotic Signaling.

    Science.gov (United States)

    Simon, David J; Pitts, Jason; Hertz, Nicholas T; Yang, Jing; Yamagishi, Yuya; Olsen, Olav; Tešić Mark, Milica; Molina, Henrik; Tessier-Lavigne, Marc

    2016-02-25

    During development, sensory axons compete for limiting neurotrophic support, and local neurotrophin insufficiency triggers caspase-dependent axon degeneration. The signaling driving axon degeneration upon local deprivation is proposed to reside within axons. Our results instead support a model in which, despite the apoptotic machinery being present in axons, the cell body is an active participant in gating axonal caspase activation and axon degeneration. Loss of trophic support in axons initiates retrograde activation of a somatic pro-apoptotic pathway, which, in turn, is required for distal axon degeneration via an anterograde pro-degenerative factor. At a molecular level, the cell body is the convergence point of two signaling pathways whose integrated action drives upregulation of pro-apoptotic Puma, which, unexpectedly, is confined to the cell body. Puma then overcomes inhibition by pro-survival Bcl-xL and Bcl-w and initiates the anterograde pro-degenerative program, highlighting the role of the cell body as an arbiter of large-scale axon removal. PMID:26898330

  4. Analysis of the apparent biphasic axonal transport kinetics of fucosylated glycoproteins

    International Nuclear Information System (INIS)

    Following intraocular injection of [3H]fucose, the accumulation of transported radioactivity arriving at the superior colliculus peaks within a few hours and decays with a time course of hours. Then, over a period of several days, radioactivity again accumulates at the superior colliculus and then decays with a half-life of days. Such data have been interpreted as evidence for both a group of rapidly released, rapidly transported glycoproteins (first peak) and a group of slowly released but rapidly transported glycoproteins (second peak). This supposition was investigated by studying in more detail the metabolism of some individual fucosylated proteins in both the retina and superior colliculus. It was noted that much of the radioactivity incorporated in fucosylated glycoproteins at the retina was rapidly metabolized, while the remainder of the fucosylated moieties had a metabolic half-life on the order of days. In other experiments [35S]methionine was injected intraocularly, the metabolism in the retina was examined and a study was made of the kinetics of transport to the superior colliculus of the peptide backbone of these same individual proteins. In contrast to the two waves of accumulation of radioactivity from [3H]fucose, accumulation of radioactivity of the peptide backbone of the same glycoproteins was monophasic. The author's explanation of these data involves the presence of two types of fucose moieties on the peptides. One group of fucose moieties is labile and is lost from the peptide backbone over a period of hours. Other fucose moieties are approximately as metabolically stable as the peptide backbones to which they are attached. The actual peptide backbones of the glycoproteins are committed to rapid transport over a period of several days

  5. In vivo labelling and axonal transport of monoamine oxidase in the rat basal ganglia using radioactive pargyline

    International Nuclear Information System (INIS)

    The enzyme monoamine oxidase was labelled in the rat striatum or substantia nigra with locally injected radioactive pargyline. The binding was prevented by a pretreatment with non-radioactive pargyline, or with a combination of clorgyline and deprenyl. Most of the MAO labelled with 3H-pargyline was of the B-type, but also some MAO-A was labelled, as shown in rats pretreated with clorgyline or deprenyl separately. Seven days after the injection of (3H)-pargyline into the striatum a significant labelling was observed in the substantia nigra. This labelling was clorgyline sensitive, indicating type A MAO, and was not present when striatal neurons were destroyed with kainic acid. Labelling of the striatum following 3H-pargyline injection into the substantia nigra was also less in kainate intoxicated striata. Damage of nigral dopamine neurons with 6-hydroxydopmaine did not influence the distribution of the label. Thus by using 3H-pargyline, specific labelling and axonal transport of type A MAO in striatal neurons projecting to the substantia nigra was demonstrated. (Author)

  6. Mechanism underlying the anterograde transport of the influenza A virus transmembrane proteins and genome in host cytoplasm%甲型流感病毒蛋白和遗传物质在宿主细胞质内顺向转运过程及其机制

    Institute of Scientific and Technical Information of China (English)

    池晓娟; 王松; 黄一帆; 陈吉龙

    2012-01-01

    流感病毒的蛋白和基因组在宿主细胞内能否正确地转运到相关部位,直接影响到病毒颗粒的形态发生.流感病毒跨膜蛋白(HA、NA和M2)主要通过宿主细胞的运输膜泡实现转运,而宿主细胞的蛋白转运机器参与了这一过程.新合成的流感病毒核糖核蛋白复合物(vRNPs)出核后,通过与活化的Rab 11相结合,聚集于邻近微管组织中心(MTOC)的胞内体.然后以运输小膜泡的形式,沿着MTOC的微管网络向细胞膜方向转运.跨膜蛋白和基因组在细胞质内的转运受一些宿主因子的调控,如ARHGAP21和小G蛋白Cdc42能够调节NA蛋白向细胞膜转运,Rab11协助vRNPs从MTOC向细胞膜转运.文中主要讨论新合成的流感病毒跨膜蛋白和遗传物质在宿主细胞质内的顺向转运(Anterograde transport)过程与调控.%Influenza virus assembly requires the completion of viral protein and vRNP transport to the assembly site at the plasma membrane. Therefore, efficient regulation of intracellular transport of the viral proteins and vRNPs to the surface of the host cell is especially important for virus morphogenesis. Influenza A virus uses the machineries of host cells to transport its own components including ribonucleoproteins (vRNPs) and three transmembrane proteins hemagglutinin (HA), neuraminidase (NA) and matrix 2 protein (M2). It has been shown that newly synthesized vRNPs are associated with active form of Rab 11 and accumulate at recycling endosomes adjacent to the microtubule organizing center (MTOC) following nuclear export. Subsequently, they are transported along the microtubule network toward the plasma membranes in cargo vesicles. The viral transmembrane proteins are translated on the rough endoplasmic reticulum and transported to the virus assembly site at the plasma membrane. It has been found that several host factors such as ARHGAP21 and GTPase Cdc42 are involved in regulation of intracellular trafficking of influenza A virus

  7. A temporal variation in nonneuronal protein synthesis in dorsal root ganglia and nerve and its significance to studies of axonal transport

    International Nuclear Information System (INIS)

    Protein synthesis and fast axonal transport were studied in vitro using dorsal root ganglia (DRG)-sciatic nerve preparations from the amphibian Xenopus laevis. It was observed that the rate of incorporation of [3H]leucine into protein in DRG and isolated segments of nerve began to increase 9 to 11 h after killing the animal, attaining at 13 to 17 h a maximum of 5- to 10-times preincrease (less than 9 h) values. At the same time as an increase in the rate of incorporation began, synthesis commenced in DRG and nerve exposed to cycloheximide (125 micrograms/ml). Whereas cycloheximide reduced fast axonal transport to 1 to 3% of control values in preparations maintained 20 to 24 h in vitro, cycloheximide reduced incorporation in DRG to only 80% of control values. N-terminal labeling studies showed that both the increased incorporation and cycloheximide-insensitive incorporation resulted from protein synthesis. Autoradiographic and incorporation studies indicated that nonneuronal cells situated in the ganglion capsule and perineural sheath of the nerve were responsible for both the increased incorporation and cycloheximide-insensitive synthesis. The findings have implications for the study of axonal transport

  8. Axonal sprouting regulates myelin basic protein gene expression in denervated mouse hippocampus

    DEFF Research Database (Denmark)

    Jensen, M B; Poulsen, F R; Finsen, B

    2000-01-01

    radiatum of CA3 and the dentate hilus, which display axonal sprouting but no degenerative changes or microglial activation, and (2) the outer part of the molecular layer of the fascia dentata, and in stratum moleculare of CA3 and stratum lacunosum-moleculare of CA1, areas that display dense anterograde...

  9. Sorting of Dendritic and Axonal Vesicles at the Pre-axonal Exclusion Zone

    Directory of Open Access Journals (Sweden)

    Ginny G. Farías

    2015-11-01

    Full Text Available Polarized sorting of newly synthesized proteins to the somatodendritic and axonal domains of neurons occurs by selective incorporation into distinct populations of vesicular transport carriers. An unresolved issue is how the vesicles themselves are sorted to their corresponding neuronal domains. Previous studies concluded that the axon initial segment (AIS is an actin-based filter that selectively prevents passage of somatodendritic vesicles into the axon. We find, however, that most somatodendritic vesicles fail to enter the axon at a more proximal region in the axon hillock, herein referred to as the pre-axonal exclusion zone (PAEZ. Forced coupling of a somatodendritic cargo protein to an axonally directed kinesin is sufficient to drive transport of whole somatodendritic vesicles through the PAEZ toward the distal axon. Based on these findings, we propose that polarized sorting of transport vesicles occurs at the PAEZ and depends on the ability of the vesicles to acquire an appropriately directed microtubule motor.

  10. Effects of proton irradiation of the lumbar intumescence on intra-axonal transport of acetylcholine and cholinergic enzymes in rat sciatic nerve

    International Nuclear Information System (INIS)

    The content and intra-axonal transport of acetylcholine (ACh) and the cholinergic enzymes cholineacetyl-transferase (CAT) and ACh-esterase (AChE) in sciatic nerve were investigated in rats following single dose proton irradiation of the lumbar intumescence of the spinal cord with 60 Gy or 200 Gy. One, 7 or 30 days after irradiation nerve-crush operations were performed 12 hours before killing and the levels of ACh and enzyme activities in nerve segments relative to the crushes were estimated by biologic (ACh) to chemical (enzyme) methods. The results indicate that alterations in intra-neuronal dynamics of ACh and related enzymes are not a major cause for the development of neurologic symptoms of the motor system after irradiation, and that descending myelinated axons are of minor importance for the regulation of cholinergic substances in rat motor nerves. (Auth.)

  11. A Model of Anterograde Oxygenated Lung Blood Flow in Acardia.

    Science.gov (United States)

    Marinakis, Sotirios; Burki, Marco; Abdel-Sayed, Saad; von Segesser, Ludwig Karl

    2016-01-01

    In extreme situations such as hyperacute rejection of heart transplant or major heart trauma, heart explantation and extracorporeal membrane oxygenation (ECMO) hemodynamic support might be the only means for survival. In our previous model of acardia, pulmonary artery (PA) was clamped and did not receive any anterograde blood flow. A model of anterograde PA perfusion might be necessary to avoid ischemic pulmonary damage in prolonged ECMO in acardia. The aim of this study was to describe the surgical technique and to determine the feasibility of an anterograde lung perfusion in acardia through the anastomosis of the right internal mammary artery (RIMA) to the PA. A venoarterial cardiopulmonary bypass was established in three pigs (72 ± 2.6 kg) by the transjugular insertion to the caval axis of a double-staged cannula with carotid artery return. Heart was excised and ECMO was established as previously reported. Right internal mammary artery was harvested and after measurement of its output (93.3 ± 5.8 ml/min, representing 2.17% ± 0.15% of total pump flow), it was anastomosed to PA. Right internal mammary artery anastomosis to PA is a feasible, safe, and easy to perform maneuver assuring an anterograde lung perfusion in acardia. PMID:27442854

  12. Axonal tubulin and axonal microtubules: biochemical evidence for cold stability

    OpenAIRE

    1984-01-01

    Nerve extracts containing tubulin labeled by axonal transport were analyzed by electrophoresis and differential extraction. We found that a substantial fraction of the tubulin in the axons of the retinal ganglion cell of guinea pigs is not solubilized by conventional methods for preparation of microtubules from whole brain. In two-dimensional polyacrylamide gel electrophoresis this cold-insoluble tubulin was biochemically distinct from tubulin obtained from whole brain microtubules prepared b...

  13. Isolation and analyses of axonal ribonucleoprotein complexes.

    Science.gov (United States)

    Doron-Mandel, Ella; Alber, Stefanie; Oses, Juan A; Medzihradszky, Katalin F; Burlingame, Alma L; Fainzilber, Mike; Twiss, Jeffery L; Lee, Seung Joon

    2016-01-01

    Cytoskeleton-dependent RNA transport and local translation in axons are gaining increased attention as key processes in the maintenance and functioning of neurons. Specific axonal transcripts have been found to play roles in many aspects of axonal physiology including axon guidance, axon survival, axon to soma communication, injury response and regeneration. This axonal transcriptome requires long-range transport that is achieved by motor proteins carrying transcripts as messenger ribonucleoprotein (mRNP) complexes along microtubules. Other than transport, the mRNP complex plays a major role in the generation, maintenance, and regulation of the axonal transcriptome. Identification of axonal RNA-binding proteins (RBPs) and analyses of the dynamics of their mRNPs are of high interest to the field. Here, we describe methods for the study of interactions between RNA and proteins in axons. First, we describe a protocol for identifying binding proteins for an RNA of interest by using RNA affinity chromatography. Subsequently, we discuss immunoprecipitation (IP) methods allowing the dissection of protein-RNA and protein-protein interactions in mRNPs under various physiological conditions. PMID:26794529

  14. Connections of the lateral reticular nucleus to the lateral vestibular nucleus in the rat. An anterograde tracing study with Phaseolus vulgaris leucoagglutinin

    NARCIS (Netherlands)

    T.J.H. Ruigrok (Tom); M. Cella (Massimo); J. Voogd

    1995-01-01

    textabstractEfferent projections from the lateral reticular nucleus in the rat were investigated with anterograde transport of Phaseolus vulgaris leucoagglutinin. Besides the well known mossy fibre connections to the cerebellar cortex and collaterals to the cerebellar nuclei, a substantial bilateral

  15. Neurofilament spacing, phosphorylation, and axon diameter in regenerating and uninjured lamprey axons.

    Science.gov (United States)

    Pijak, D S; Hall, G F; Tenicki, P J; Boulos, A S; Lurie, D I; Selzer, M E

    1996-05-13

    uncut GRAs but were also highly phosphorylated. Thus, in the lamprey, NF phosphorylation may not control axon diameter directly through electrorepulsive charges that increase NF sidearm extension and NF spacing. It is possible that phosphorylation of NFs normally influences axon diameter through indirect mechanisms, such as the slowing of NF transport and the formation of a stationary cytoskeletal lattice, as has been proposed by others. Such a mechanism could be overridden during regeneration, when a more compact, phosphorylated NF backbone might add mechanical stiffness that promotes the advance of the neurite tip within a restricted central nervous system environment. PMID:8744444

  16. Neural Correlate of Anterograde Amnesia in Wernicke-Korsakoff Syndrome.

    Science.gov (United States)

    Nahum, Louis; Pignat, Jean-Michel; Bouzerda-Wahlen, Aurélie; Gabriel, Damien; Liverani, Maria Chiara; Lazeyras, François; Ptak, Radek; Richiardi, Jonas; Haller, Sven; Thorens, Gabriel; Zullino, Daniele F; Guggisberg, Adrian G; Schnider, Armin

    2015-09-01

    The neural correlate of anterograde amnesia in Wernicke-Korsakoff syndrome (WKS) is still debated. While the capacity to learn new information has been associated with integrity of the medial temporal lobe (MTL), previous studies indicated that the WKS is associated with diencephalic lesions, mainly in the mammillary bodies and anterior or dorsomedial thalamic nuclei. The present study tested the hypothesis that amnesia in WKS is associated with a disrupted neural circuit between diencephalic and hippocampal structures. High-density evoked potentials were recorded in four severely amnesic patients with chronic WKS, in five patients with chronic alcoholism without WKS, and in ten age matched controls. Participants performed a continuous recognition task of pictures previously shown to induce a left medial temporal lobe dependent positive potential between 250 and 350 ms. In addition, the integrity of the fornix was assessed using diffusion tensor imaging (DTI). WKS, but not alcoholic patients without WKS, showed absence of the early, left MTL dependent positive potential following immediate picture repetitions. DTI indicated disruption of the fornix, which connects diencephalic and hippocampal structures. The findings support an interpretation of anterograde amnesia in WKS as a consequence of a disconnection between diencephalic and MTL structures with deficient contribution of the MTL to rapid consolidation. PMID:25148770

  17. A surviving intact branch stabilizes remaining axon architecture after injury as revealed by in vivo imaging in the mouse spinal cord.

    Science.gov (United States)

    Lorenzana, Ariana O; Lee, Jae K; Mui, Matthew; Chang, Amy; Zheng, Binhai

    2015-05-20

    The complex morphology of axons presents a challenge in understanding axonal responses to injury and disease. By in vivo two-photon imaging of spinal dorsal column sensory axons, we systematically examined the effect of injury location relative to the main bifurcation point on axon degeneration and regeneration following highly localized laser injuries. Retrograde but not anterograde degeneration was strongly blocked at the bifurcation point at both the acute and subacute phases. Eliminating either the ascending or descending branch led to a poor regenerative response, while eliminating both led to a strong regenerative response. Thus, a surviving intact branch suppresses both retrograde degeneration and regeneration of the injured branch, thereby preserving the remaining axon architecture. Regenerating axons exhibited a dynamic pattern with alternating phases of regeneration and pruning over a chronic period. In vivo imaging continues to reveal new insights on axonal responses to injury in the mammalian spinal cord. PMID:25937174

  18. Localization of Axonal Motor Molecules Machinery in Neurodegenerative Disorders

    Directory of Open Access Journals (Sweden)

    Fulvio Florenzano

    2012-04-01

    Full Text Available Axonal transport and neuronal survival depend critically on active transport and axon integrity both for supplying materials and communication to different domains of the cell body. All these actions are executed through cytoskeleton, transport and regulatory elements that appear to be disrupted in neurodegenerative diseases. Motor-driven transport both supplies and clears distal cellular portions with proteins and organelles. This transport is especially relevant in projection and motor neurons, which have long axons to reach the farthest nerve endings. Thus, any disturbance of axonal transport may have severe consequences for neuronal function and survival. A growing body of literature indicates the presence of alterations to the motor molecules machinery, not only in expression levels and phosphorylation, but also in their subcellular distribution within populations of neurons, which are selectively affected in the course of neurodegenerative diseases. The implications of this altered subcellular localization and how this affects axon survival and neuronal death still remain poorly understood, although several hypotheses have been suggested. Furthermore, cytoskeleton and transport element localization can be selectively disrupted in some disorders suggesting that specific loss of the axonal functionality could be a primary hallmark of the disorder. This can lead to axon degeneration and neuronal death either directly, through the functional absence of essential axonal proteins, or indirectly, through failures in communication among different cellular domains. This review compares the localization of cytoskeleton and transport elements in some neurodegenerative disorders to ask what aspects may be essential for axon survival and neuronal death.

  19. Computing along the axon

    Institute of Scientific and Technical Information of China (English)

    Chen Haiming; Tseren-Onolt Ishdorj; Gheorghe Pǎun

    2007-01-01

    A special form of spiking neural P systems, called axon P systems, corresponding to the activity of Ranvier nodes of neuron axon, is considered and a class of SN-like P systems where the computation is done along the axon is introduced and their language generative power is investigated.

  20. Giant Axon Formation in Mice Lacking Kell, XK, or Kell and XK

    Science.gov (United States)

    Zhu, Xiang; Cho, Eun-Sook; Sha, Quan; Peng, Jianbin; Oksov, Yelena; Kam, Siok Yuen; Ho, Mengfatt; Walker, Ruth H.; Lee, Soohee

    2015-01-01

    McLeod neuroacanthocytosis syndrome (MLS) is a rare X-linked multisystem disease caused by XK gene mutations and characterized by hematological and neurological abnormalities. XK, a putative membrane transporter, is expressed ubiquitously and is covalently linked to Kell, an endothelin-3-converting enzyme (ECE-3). Absence of XK results in reduction of Kell at sites where both proteins are coexpressed. To elucidate the functional roles of XK, Kell, and the XK–Kell complex associated with pathogenesis in MLS, we studied the pathology of the spinal cord, anterior roots, sciatic nerve, and skeletal muscle from knockout mouse models, using Kel−/−, Xk−/−, Kel−/−Xk−/−, and wild-type mice aged 6 to 18 months. A striking finding was that giant axons were frequently associated with paranodal demyelination. The pathology suggests probable anterograde progression from the spinal cord to the sciatic nerve. The neuropathological abnormalities were found in all three genotypes, but were more marked in the double-knockout Kel−/−Xk−/− mice than in either Kel−/− or Xk−/− mice. Skeletal muscles from Xk−/− and Kel−/−Xk−/− mice showed mild abnormalities, but those from Kel−/− mice were similar to the wild type. The more marked neuropathological abnormalities in Kel−/−Xk−/− mice suggest a possible functional association between XK and Kell in nonerythroid tissues. PMID:24405768

  1. Connections of the lateral reticular nucleus to the lateral vestibular nucleus in the rat. An anterograde tracing study with Phaseolus vulgaris leucoagglutinin

    OpenAIRE

    Ruigrok, Tom; Cella, Massimo; Voogd, J.

    1995-01-01

    textabstractEfferent projections from the lateral reticular nucleus in the rat were investigated with anterograde transport of Phaseolus vulgaris leucoagglutinin. Besides the well known mossy fibre connections to the cerebellar cortex and collaterals to the cerebellar nuclei, a substantial bilateral projection to the lateral vestibular nucleus was found. Terminal arborizations found within this nucleus appeared to detach from the reticulocerebellar fibres in the cerebellar white matter and en...

  2. Axonal transport of labelled proteins and increased functional activity in sciatic nerve of the frog Rana hexadactyla in vitro

    International Nuclear Information System (INIS)

    In vitro speed of fast moving labelled protein fraction was investigated in the lumbar 8 nerve of R.hexadactyla during normal and electrical stimulation conditions. 3H-leucine labelled oroteins moved in a proximo-distal direction at a speed of 144 mm/day at 25 deg C. No change was observed in the rate of proteins transported in stimulated nerves but the amount of protein bound radioactivity increased over stimulation. In ligature experiments, amount of labelled proteins accumulating at a ligature was higher in stimulated nerves. Electrical stimulation of nerve resulted in an increase in protein synthetic rate in the respective ganglion. (author)

  3. A sinister cause of anterograde amnesia: painless aortic dissection.

    Science.gov (United States)

    April, Michael D; Fossum, Kurt; Hounshell, Charles; Stolper, Katherine; Spear, Leigh; Semelrath, Kevin

    2015-07-01

    Aortic dissection is a frequently devastating diagnosis classically associated with severe chest pain.We present a case of painless aortic dissection with anterograde amnesia. An 84-year-old man was brought to the emergency department by ambulance, when his wife noted that he developed acute onset complete loss of short-term memory. Medical history was notable for a 4.5-cm fusiform thoracic aortic root aneurysm. On arrival,he denied pain or syncope.On examination, he was mildly hypotensive(110/59 mm Hg); and there were no murmurs, pulse deficits, or focal neurologic deficits. During his stay, he developed left flank pain. Chest radiography demonstrated subtle mediastinal widening and obscuration of the aortic knob compared with previous films. Computed tomography revealed an extensive intimal flap consistent with an aortic dissection involving the sinus of Valsalva and left renal artery. The patient subsequently developed acute onset chest pain after which he became unresponsive. Echocardiography demonstrated tamponade physiology.The family decided to transition to comfort care measures, and the patient died soon after.We identified 7 other cases in the literature of aortic dissection cases with presentations consistent with transient global amnesia,5 of which without neurologic deficits and 3 of which without pain. This case highlights the imperative of a thorough history and high index of suspicion for this catastrophic diagnosis in patients with transient global amnesia who otherwise might be expected to have an excellent prognosis and little need for diagnostic work-up. PMID:25649752

  4. Biotinylated dextran amine anterograde tracing of the canine corticospinal tract

    Institute of Scientific and Technical Information of China (English)

    Xiao Han; Guangming Lv; Huiqun Wu; Dafeng Ji; Zhou Sun; Yaofu Li; Lemin Tang

    2012-01-01

    In this study, biotinylated dextran amine (BDA) was microinjected into the left cortical motor area of the canine brain. Fluorescence microscopy results showed that a large amount of BDA-labeled pyramidal cells were visible in the left cortical motor area after injection. In the left medulla oblongata, the BDA-labeled corticospinal tract was evenly distributed, with green fluorescence that had a clear boundary with the surrounding tissue. The BDA-positive corticospinal tract entered into the right lateral funiculus of the spinal cord and descended into the posterior part of the right lateral funiculus, close to the posterior horn, from cervical to sacral segments. There was a small amount of green fluorescence in the sacral segment. The distribution of BDA labeling in the canine central nervous system was consistent with the course of the corticospinal tract. Fluorescence labeling for BDA gradually diminished with time after injection. Our findings indicate that the BDA anterograde tracing technique can be used to visualize the localization and trajectory of the corticospinal tract in the canine central nervous system.

  5. Motor Axon Pathfinding

    OpenAIRE

    Bonanomi, Dario; Pfaff, Samuel L

    2010-01-01

    Motor neurons are functionally related, but represent a diverse collection of cells that show strict preferences for specific axon pathways during embryonic development. In this article, we describe the ligands and receptors that guide motor axons as they extend toward their peripheral muscle targets. Motor neurons share similar guidance molecules with many other neuronal types, thus one challenge in the field of axon guidance has been to understand how the vast complexity of brain connection...

  6. Defective lysosomal proteolysis and axonal transport are early pathogenic events that worsen with age leading to increased APP metabolism and synaptic Abeta in transgenic APP/PS1 hippocampus

    Directory of Open Access Journals (Sweden)

    Torres Manuel

    2012-11-01

    Full Text Available Abstract Background Axonal pathology might constitute one of the earliest manifestations of Alzheimer disease. Axonal dystrophies were observed in Alzheimer’s patients and transgenic models at early ages. These axonal dystrophies could reflect the disruption of axonal transport and the accumulation of multiple vesicles at local points. It has been also proposed that dystrophies might interfere with normal intracellular proteolysis. In this work, we have investigated the progression of the hippocampal pathology and the possible implication in Abeta production in young (6 months and aged (18 months PS1(M146L/APP(751sl transgenic mice. Results Our data demonstrated the existence of a progressive, age-dependent, formation of axonal dystrophies, mainly located in contact with congophilic Abeta deposition, which exhibited tau and neurofilament hyperphosphorylation. This progressive pathology was paralleled with decreased expression of the motor proteins kinesin and dynein. Furthermore, we also observed an early decrease in the activity of cathepsins B and D, progressing to a deep inhibition of these lysosomal proteases at late ages. This lysosomal impairment could be responsible for the accumulation of LC3-II and ubiquitinated proteins within axonal dystrophies. We have also investigated the repercussion of these deficiencies on the APP metabolism. Our data demonstrated the existence of an increase in the amyloidogenic pathway, which was reflected by the accumulation of hAPPfl, C99 fragment, intracellular Abeta in parallel with an increase in BACE and gamma-secretase activities. In vitro experiments, using APPswe transfected N2a cells, demonstrated that any imbalance on the proteolytic systems reproduced the in vivo alterations in APP metabolism. Finally, our data also demonstrated that Abeta peptides were preferentially accumulated in isolated synaptosomes. Conclusion A progressive age-dependent cytoskeletal pathology along with a reduction of

  7. Determinants of axonal regeneration

    OpenAIRE

    Frisén, J

    1997-01-01

    Axons often regrow to their targets and lost functions may be restored after an injury in the peripheral nervous system. In contrast, axonal regeneration is generally very limited after injuries in the central nervous system, and functional impairment is usually permanent. The regenerative capacity depends on intrinsic neuronal factors as weil as the interaction of neurons with other cells. Glial cells may, in different situations, either support or inhibit axo...

  8. Human CFEOM1 mutations attenuate KIF21A autoinhibition and cause oculomotor axon stalling

    OpenAIRE

    Cheng, Long; Desai, Jigar; Miranda, Carlos J.; Duncan, Jeremy S.; Qiu, Weihong; Nugent, Alicia A.; Kolpak, Adrianne L.; Wu, Carrie C.; Drokhlyansky, Eugene; Delisle, Michelle M.; Chan, Wai-Man; Wei, Yan; Propst, Friedrich; Reck-Peterson, Samara L; Fritzsch, Bernd

    2014-01-01

    The ocular motility disorder “Congenital fibrosis of the extraocular muscles type 1″ (CFEOM1) results from heterozygous mutations altering the motor and 3rd coiled-coil stalk of the anterograde kinesin, KIF21A. We demonstrate that Kif21a knock-in mice harboring the most common human mutation develop CFEOM. The developing axons of the oculomotor nerve’s superior division stall in the proximal nerve; the growth cones enlarge, extend excessive filopodia, and assume random trajectories. Inferior ...

  9. Different types of spinal afferent nerve endings in stomach and esophagus identified by anterograde tracing from dorsal root ganglia.

    Science.gov (United States)

    Spencer, Nick J; Kyloh, Melinda; Beckett, Elizabeth A; Brookes, Simon; Hibberd, Tim

    2016-10-15

    In visceral organs of mammals, most noxious (painful) stimuli as well as innocuous stimuli are detected by spinal afferent neurons, whose cell bodies lie in dorsal root ganglia (DRGs). One of the major unresolved questions is the location, morphology, and neurochemistry of the nerve endings of spinal afferents that actually detect these stimuli in the viscera. In the upper gastrointestinal (GI) tract, there have been many anterograde tracing studies of vagal afferent endings, but none on spinal afferent endings. Recently, we developed a technique that now provides selective labeling of only spinal afferents. We used this approach to identify spinal afferent nerve endings in the upper GI tract of mice. Animals were anesthetized, and injections of dextran-amine were made into thoracic DRGs (T8-T12). Seven days post surgery, mice were euthanized, and the stomach and esophagus were removed, fixed, and stained for calcitonin gene-related peptide (CGRP). Spinal afferent axons were identified that ramified extensively through many rows of myenteric ganglia and formed nerve endings in discrete anatomical layers. Most commonly, intraganglionic varicose endings (IGVEs) were identified in myenteric ganglia of the stomach and varicose simple-type endings in the circular muscle and mucosa. Less commonly, nerve endings were identified in internodal strands, blood vessels, submucosal ganglia, and longitudinal muscle. In the esophagus, only IGVEs were identified in myenteric ganglia. No intraganglionic lamellar endings (IGLEs) were identified in the stomach or esophagus. We present the first identification of spinal afferent endings in the upper GI tract. Eight distinct types of spinal afferent endings were identified in the stomach, and most of them were CGRP immunoreactive. J. Comp. Neurol. 524:3064-3083, 2016. © 2016 Wiley Periodicals, Inc. PMID:27019197

  10. Protein phosphorylation: Localization in regenerating optic axons

    International Nuclear Information System (INIS)

    A number of axonal proteins display changes in phosphorylation during goldfish optic nerve regeneration. (1) To determine whether the phosphorylation of these proteins was closely linked to their synthesis in the retinal ganglion cell body, cycloheximide was injected intraocularly into goldfish whose optic nerves had been regenerating for 3 weeks. Cycloheximide reduced the incorporation of [3H]proline and 32P orthophosphate into total nerve protein by 84% and 46%, respectively. Of the 20 individual proteins examined, 17 contained less than 15% of the [3H]proline label measured in corresponding controls, whereas 18 proteins contained 50% or more of the 32P label, suggesting that phosphorylation was largely independent of synthesis. (2) To determine whether the proteins were phosphorylated in the ganglion cell axons, axonal transport of proteins was blocked by intraocular injection of vincristine. Vincristine reduced [3H]proline labeling of total protein by 88% and 32P labeling by 49%. Among the individual proteins [3H]proline labeling was reduced by 90% or more in 18 cases but 32P labeling was reduced only by 50% or less. (3) When 32P was injected into the cranial cavity near the ends of the optic axons, all of the phosphoproteins were labeled more intensely in the optic tract than in the optic nerve. These results suggest that most of the major phosphoproteins that undergo changes in phosphorylation in the course of regeneration are phosphorylated in the optic axons

  11. Anterograde and Retrograde Amnesia of Place Discrimination in Retrosplenial Cortex and Hippocampal Lesioned Rats

    Science.gov (United States)

    Haijima, Asahi; Ichitani, Yukio

    2008-01-01

    Retrograde and anterograde amnesic effects of excitotoxic lesions of the rat retrosplenial cortex (RS) and hippocampus (HPC) were investigated. To test retrograde amnesia, rats were trained with two-arm place discrimination in a radial maze 4 wk and 1 d before surgery with a different arm pair, respectively. In the retention test 1 wk after…

  12. Neurofilament gene expression: a major determinant of axonal caliber

    International Nuclear Information System (INIS)

    Within the wide spectrum of axonal diameters occurring in mammalian nerve fibers, each class of neurons has a relatively restricted range of axonal calibers. The control of caliber has functional significance because diameter is the principal determinant of conduction velocity in myelinated nerve fibers. Previous observations support the hypothesis that neurofilaments (NF) are major intrinsic determinants of axonal caliber in large myelinated nerve fibers. Following interruption of axons (axotomy) by crushing or cutting a peripheral nerve, caliber is reduced in the proximal axonal stumps, which extend from the cell bodies to the site of axotomy. This reduction in axonal caliber in the proximal stumps is associated with a selective diminution in the amount of NF protein undergoing slow axonal transport in these axons, with a decrease in axonal NF content, and with reduced conduction velocity. The present report demonstrates that changes in axonal caliber after axotomy correlate with a selective alteration in NF gene expression. Hybridization with specific cDNAs was used to measure levels of mRNA encoding the 68-kDa neurofilament protein (NF68), β-tubulin, and actin in lumbar sensory neurons of rat at various times after crushing the sciatic nerve. Between 4 and 42 days after axotomy by nerve crush, the levels of NF68 mRNA were reduced 2- to 3-fold. At the same times, the levels of tubulin and actin mRNAs were increased several-fold. These findings support the hypothesis that the expression of a single set of neuron-specific genes (encoding NF) directly determines axonal caliber, a feature neuronal morphology with important consequences for physiology and behavior

  13. Anterograde jejunojejunal intussusception resulted in acute efferent loop syndrome after subtotal gastrectomy

    Institute of Scientific and Technical Information of China (English)

    Jung; Myun; Kwak; Jin; Kim; Sung; Ock; Suh

    2010-01-01

    Postoperative intussusception is an unusual clinical entity in adults,and is rarely encountered as a complication following gastric surgery.The most common type after gastric surgery is retrograde jejunogastric intussusception,and jejunojejunal intussusception has been rarely reported.We report a case of anterograde jejunojejunal intussusception after radical subtotal gastrectomy with Billroth Ⅱ anastomosis in a 38-year-old Korean woman with early gastric cancer,and include a review of the literature on thi...

  14. Axonal PPARγ promotes neuronal regeneration after injury.

    Science.gov (United States)

    Lezana, Juan Pablo; Dagan, Shachar Y; Robinson, Ari; Goldstein, Ronald S; Fainzilber, Mike; Bronfman, Francisca C; Bronfman, Miguel

    2016-06-01

    PPARγ is a ligand-activated nuclear receptor best known for its involvement in adipogenesis and glucose homeostasis. PPARγ activity has also been associated with neuroprotection in different neurological disorders, but the mechanisms involved in PPARγ effects in the nervous system are still unknown. Here we describe a new functional role for PPARγ in neuronal responses to injury. We found both PPAR transcripts and protein within sensory axons and observed an increase in PPARγ protein levels after sciatic nerve crush. This was correlated with increased retrograde transport of PPARγ after injury, increased association of PPARγ with the molecular motor dynein, and increased nuclear accumulation of PPARγ in cell bodies of sensory neurons. Furthermore, PPARγ antagonists attenuated the response of sensory neurons to sciatic nerve injury, and inhibited axonal growth of both sensory and cortical neurons in culture. Thus, axonal PPARγ is involved in neuronal injury responses required for axonal regeneration. Since PPARγ is a major molecular target of the thiazolidinedione (TZD) class of drugs used in the treatment of type II diabetes, several pharmaceutical agents with acceptable safety profiles in humans are available. Our findings provide motivation and rationale for the evaluation of such agents for efficacy in central and peripheral nerve injuries. PMID:26446277

  15. Impulse conduction increases mitochondrial transport in adult mammalian peripheral nerves in vivo.

    Directory of Open Access Journals (Sweden)

    Marija Sajic

    2013-12-01

    Full Text Available Matching energy supply and demand is critical in the bioenergetic homeostasis of all cells. This is a special problem in neurons where high levels of energy expenditure may occur at sites remote from the cell body, given the remarkable length of axons and enormous variability of impulse activity over time. Positioning mitochondria at areas with high energy requirements is an essential solution to this problem, but it is not known how this is related to impulse conduction in vivo. Therefore, to study mitochondrial trafficking along resting and electrically active adult axons in vivo, confocal imaging of saphenous nerves in anaesthetised mice was combined with electrical and pharmacological stimulation of myelinated and unmyelinated axons, respectively. We show that low frequency activity induced by electrical stimulation significantly increases anterograde and retrograde mitochondrial traffic in comparison with silent axons. Higher frequency conduction within a physiological range (50 Hz dramatically further increased anterograde, but not retrograde, mitochondrial traffic, by rapidly increasing the number of mobile mitochondria and gradually increasing their velocity. Similarly, topical application of capsaicin to skin innervated by the saphenous nerve increased mitochondrial traffic in both myelinated and unmyelinated axons. In addition, stationary mitochondria in axons conducting at higher frequency become shorter, thus supplying additional mitochondria to the trafficking population, presumably through enhanced fission. Mitochondria recruited to the mobile population do not accumulate near Nodes of Ranvier, but continue to travel anterogradely. This pattern of mitochondrial redistribution suggests that the peripheral terminals of sensory axons represent sites of particularly high metabolic demand during physiological high frequency conduction. As the majority of mitochondrial biogenesis occurs at the cell body, increased anterograde

  16. Brain gangliosides in axon-myelin stability and axon regeneration

    OpenAIRE

    Schnaar, Ronald L.

    2009-01-01

    Gangliosides, sialic acid-bearing glycosphingolipids, are expressed at high abundance and complexity in the brain. Altered ganglioside expression results in neural disorders, including seizures and axon degeneration. Brain gangliosides function, in part, by interacting with a ganglioside-binding lectin, myelin-associated glycoprotein (MAG). MAG, on the innermost wrap of the myelin sheath, binds to gangliosides GD1a and GT1b on axons. MAG-ganglioside binding ensures optimal axon-myelin cell-ce...

  17. Microfluidic control of axonal guidance

    Science.gov (United States)

    Gu, Ling; Black, Bryan; Ordonez, Simon; Mondal, Argha; Jain, Ankur; Mohanty, Samarendra

    2014-10-01

    The precision of axonal pathfinding and the accurate formation of functional neural circuitry are crucial for an organism during development as well as during adult central and peripheral nerve regeneration. While chemical cues are believed to be primarily responsible for axonal pathfinding, we hypothesize that forces due to localized fluid flow may directly affect neuronal guidance during early organ development. Here, we report direct evidence of fluid flow influencing axonal migration, producing turning angles of up to 90°. Microfluidic flow simulations indicate that an axon may experience significant bending force due to cross-flow, which may contribute to the observed axonal turning. This method of flow-based guidance was successfully used to fasciculate one advancing axon onto another, showcasing the potential of this technique to be used for the formation of in vitro neuronal circuits.

  18. Axon-glia interaction and membrane traffic in myelin formation

    Directory of Open Access Journals (Sweden)

    Robin eWhite

    2014-01-01

    Full Text Available In vertebrate nervous systems myelination of neuronal axons has evolved to increase conduction velocity of electrical impulses with minimal space and energy requirements. Myelin is formed by specialised glial cells which ensheath axons with a lipid-rich insulating membrane. Myelination is a multi-step process initiated by axon-glia recognition triggering glial polarisation followed by targeted myelin membrane expansion and compaction. Thereby, a myelin sheath of complex subdomain structure is established. Continuous communication between neurons and glial cells is essential for myelin maintenance and axonal integrity. A diverse group of diseases, from multiple sclerosis to schizophrenia, have been linked to malfunction of myelinating cells reflecting the physiological importance of the axon-glial unit. This review describes the mechanisms of axonal signal integration by oligodendrocytes emphasising the central role of the Src-family kinase Fyn during CNS myelination. Furthermore, we discuss myelin membrane trafficking with particular focus on endocytic recycling and the control of PLP (proteolipid protein transport by SNARE proteins. Finally, PLP mistrafficking is considered in the context of myelin diseases.

  19. Human CFEOM1 mutations attenuate KIF21A autoinhibition and cause oculomotor axon stalling.

    Science.gov (United States)

    Cheng, Long; Desai, Jigar; Miranda, Carlos J; Duncan, Jeremy S; Qiu, Weihong; Nugent, Alicia A; Kolpak, Adrianne L; Wu, Carrie C; Drokhlyansky, Eugene; Delisle, Michelle M; Chan, Wai-Man; Wei, Yan; Propst, Friedrich; Reck-Peterson, Samara L; Fritzsch, Bernd; Engle, Elizabeth C

    2014-04-16

    The ocular motility disorder "Congenital fibrosis of the extraocular muscles type 1" (CFEOM1) results from heterozygous mutations altering the motor and third coiled-coil stalk of the anterograde kinesin, KIF21A. We demonstrate that Kif21a knockin mice harboring the most common human mutation develop CFEOM. The developing axons of the oculomotor nerve's superior division stall in the proximal nerve; the growth cones enlarge, extend excessive filopodia, and assume random trajectories. Inferior division axons reach the orbit but branch ectopically. We establish a gain-of-function mechanism and find that human motor or stalk mutations attenuate Kif21a autoinhibition, providing in vivo evidence for mammalian kinesin autoregulation. We identify Map1b as a Kif21a-interacting protein and report that Map1b⁻/⁻ mice develop CFEOM. The interaction between Kif21a and Map1b is likely to play a critical role in the pathogenesis of CFEOM1 and highlights a selective vulnerability of the developing oculomotor nerve to perturbations of the axon cytoskeleton. PMID:24656932

  20. Local translation and directional steering in axons

    OpenAIRE

    Lin, Andrew C; Holt, Christine E.

    2007-01-01

    The assembly of functional neural circuits in the developing brain requires neurons to extend axons to the correct targets. This in turn requires the navigating tips of axons to respond appropriately to guidance cues present along the axonal pathway, despite being cellular ‘outposts' far from the soma. Work over the past few years has demonstrated a critical role for local translation within the axon in this process in vitro, making axon guidance another process that requires spatially locali...

  1. Identification of different types of spinal afferent nerve endings that encode noxious and innocuous stimuli in the large intestine using a novel anterograde tracing technique.

    Directory of Open Access Journals (Sweden)

    Nick J Spencer

    Full Text Available In mammals, sensory stimuli in visceral organs, including those that underlie pain perception, are detected by spinal afferent neurons, whose cell bodies lie in dorsal root ganglia (DRG. One of the major challenges in visceral organs has been how to identify the different types of nerve endings of spinal afferents that transduce sensory stimuli into action potentials. The reason why spinal afferent nerve endings have been so challenging to identify is because no techniques have been available, until now, that can selectively label only spinal afferents, in high resolution. We have utilized an anterograde tracing technique, recently developed in our laboratory, which facilitates selective labeling of only spinal afferent axons and their nerve endings in visceral organs. Mice were anesthetized, lumbosacral DRGs surgically exposed, then injected with dextran-amine. Seven days post-surgery, the large intestine was removed. The characteristics of thirteen types of spinal afferent nerve endings were identified in detail. The greatest proportion of nerve endings was in submucosa (32%, circular muscle (25% and myenteric ganglia (22%. Two morphologically distinct classes innervated myenteric ganglia. These were most commonly a novel class of intraganglionic varicose endings (IGVEs and occasionally rectal intraganglionic laminar endings (rIGLEs. Three distinct classes of varicose nerve endings were found to innervate the submucosa and circular muscle, while one class innervated internodal strands, blood vessels, crypts of lieberkuhn, the mucosa and the longitudinal muscle. Distinct populations of sensory endings were CGRP-positive. We present the first complete characterization of the different types of spinal afferent nerve endings in a mammalian visceral organ. The findings reveal an unexpectedly complex array of different types of primary afferent endings that innervate specific layers of the large intestine. Some of the novel classes of nerve endings

  2. Identification of Different Types of Spinal Afferent Nerve Endings That Encode Noxious and Innocuous Stimuli in the Large Intestine Using a Novel Anterograde Tracing Technique

    Science.gov (United States)

    Spencer, Nick J.; Kyloh, Melinda; Duffield, Michael

    2014-01-01

    In mammals, sensory stimuli in visceral organs, including those that underlie pain perception, are detected by spinal afferent neurons, whose cell bodies lie in dorsal root ganglia (DRG). One of the major challenges in visceral organs has been how to identify the different types of nerve endings of spinal afferents that transduce sensory stimuli into action potentials. The reason why spinal afferent nerve endings have been so challenging to identify is because no techniques have been available, until now, that can selectively label only spinal afferents, in high resolution. We have utilized an anterograde tracing technique, recently developed in our laboratory, which facilitates selective labeling of only spinal afferent axons and their nerve endings in visceral organs. Mice were anesthetized, lumbosacral DRGs surgically exposed, then injected with dextran-amine. Seven days post-surgery, the large intestine was removed. The characteristics of thirteen types of spinal afferent nerve endings were identified in detail. The greatest proportion of nerve endings was in submucosa (32%), circular muscle (25%) and myenteric ganglia (22%). Two morphologically distinct classes innervated myenteric ganglia. These were most commonly a novel class of intraganglionic varicose endings (IGVEs) and occasionally rectal intraganglionic laminar endings (rIGLEs). Three distinct classes of varicose nerve endings were found to innervate the submucosa and circular muscle, while one class innervated internodal strands, blood vessels, crypts of lieberkuhn, the mucosa and the longitudinal muscle. Distinct populations of sensory endings were CGRP-positive. We present the first complete characterization of the different types of spinal afferent nerve endings in a mammalian visceral organ. The findings reveal an unexpectedly complex array of different types of primary afferent endings that innervate specific layers of the large intestine. Some of the novel classes of nerve endings identified

  3. Tumor necrosis factor and its p55 and p75 receptors are not required for axonal lesion-induced microgliosis in mouse fascia dentata

    DEFF Research Database (Denmark)

    Fenger, Christina; Drøjdahl, Nina; Nielsen, Martin Wirenfeldt;

    2006-01-01

    Tumor necrosis factor (TNF) is a potent pro-inflammatory and neuromodulatory cytokine. In the CNS it is produced primarily by microglia and considered to regulate microglial activation. On the basis of previous observations of increased microglial TNF mRNA synthesis in areas of anterograde axonal...... response in TNF and TNF-p55p75 receptor knock out mice and C57BL/6 mice was similar 5 days after the lesion. In addition, the microglial expression of the lysosomal-associated antigen CD68, and the clearance of MBP(+) myelin debris appeared similar in TNF and TNF-p55p75 receptor knock out mice compared to...

  4. Anterograde removal of broken femoral nails without opening the nonunion site: a new technique

    Directory of Open Access Journals (Sweden)

    Henrique Antônio Berwanger de Amorim Cabrita

    2010-01-01

    Full Text Available OBJECTIVE: We describe a new technique for removing the distal fragments of broken intramedullary femoral nails without disturbing the nonunion site. METHODS: This technique involves the application of an AO distractor prior to the removal of the nail fragments, with subsequent removal of the proximal nail fragment in an anterograde fashion and removal of the distal fragment through a medial parapatellar approach. Impaction of the fracture site is then performed with a nail that is broader than the remaining fragmented material. RESULTS: Nails were removed from five patients using the technique described above without any complications. After a mean follow-up period of 61.8 months, none of these patients showed worsened knee osteoarthritis. CONCLUSION: The original technique described in this article allows surgeons to remove the distal fragment of fractured femoral intramedullary nails without opening the nonunion focus or using special surgical instruments.

  5. Unexpected anterograde amnesia associated with Buscopan used as a predmedication for endocscopy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    It has been known that peripheral adverse event is caused by peripheral antimuscarinic action, from hyoscine butylbromide (Buscopan; Boehringer Ingelheim, Germany)used as a premedication for endoscopy. However,symptoms or signs associated with the central nervous system are rarely reported in the field of anesthesiology and peripartum labor. This central anticholinergic syndrome is likely caused by blockade of muscarinic cholinergic receptors in the central nervous system. There is no report on Buscopan-induced central anticholinergic syndrome in endoscopy room so far. Three middle-aged females unexpectedly suffered from anterograde amnesia after intramuscular injection of hyoscine butylbromide as an antispasmodic premedication for endoscopy at our endoscopy unit in the Health Promotion Center.

  6. Anterograde effects of a single electroconvulsive shock on inhibitory avoidance and on cued fear conditioning

    Directory of Open Access Journals (Sweden)

    Oliveira M.G.M.

    1998-01-01

    Full Text Available A single electroconvulsive shock (ECS or a sham ECS was administered to male 3-4-month-old Wistar rats 1, 2, and 4 h before training in an inhibitory avoidance test and in cued classical fear conditioning (measured by means of freezing time in a new environment. ECS impaired inhibitory avoidance at all times and, at 1 or 2 h before training, reduced freezing time before and after re-presentation of the ECS. These results are interpreted as a transient conditioned stimulus (CS-induced anxiolytic or analgesic effect lasting about 2 h after a single treatment, in addition to the known amnesic effect of the stimulus. This suggests that the effect of anterograde learning impairment is demonstrated unequivocally only when the analgesic/anxiolytic effect is over (about 4 h after ECS administration and that this impairment of learning is selective, affecting inhibitory avoidance but not classical fear conditioning to a discrete stimulus.

  7. Thiazolidinediones promote axonal growth through the activation of the JNK pathway.

    Directory of Open Access Journals (Sweden)

    Rodrigo A Quintanilla

    Full Text Available The axon is a neuronal process involved in protein transport, synaptic plasticity, and neural regeneration. It has been suggested that their structure and function are profoundly impaired in neurodegenerative diseases. Previous evidence suggest that Peroxisome Proliferator-Activated Receptors-γ (PPARγ promote neuronal differentiation on various neuronal cell types. In addition, we demonstrated that activation of PPARγby thiazolidinediones (TZDs drugs that selectively activate PPARγ prevent neurite loss and axonal damage induced by amyloid-β (Aβ. However, the potential role of TZDs in axonal elongation and neuronal polarity has not been explored. We report here that the activation of PPARγ by TZDs promoted axon elongation in primary hippocampal neurons. Treatments with different TZDs significantly increased axonal growth and branching area, but no significant effects were observed in neurite elongation compared to untreated neurons. Treatment with PPARγ antagonist (GW 9662 prevented TZDs-induced axonal growth. Recently, it has been suggested that the c-Jun N-terminal kinase (JNK plays an important role regulating axonal growth and neuronal polarity. Interestingly, in our studies, treatment with TZDs induced activation of the JNK pathway, and the pharmacological blockage of this pathway prevented axon elongation induced by TZDs. Altogether, these results indicate that activation of JNK induced by PPARγactivators stimulates axonal growth and accelerates neuronal polarity. These novel findings may contribute to the understanding of the effects of PPARγ on neuronal differentiation and validate the use of PPARγ activators as therapeutic agents in neurodegenerative diseases.

  8. Analysis of axonal regeneration in the central and peripheral nervous systems of the NG2-deficient mouse

    Directory of Open Access Journals (Sweden)

    Lieberman Alexander R

    2007-09-01

    Full Text Available Abstract Background The chondroitin sulphate proteoglycan NG2 blocks neurite outgrowth in vitro and has been proposed as a major inhibitor of axonal regeneration in the CNS. Although a substantial body of evidence underpins this hypothesis, it is challenged by recent findings including strong expression of NG2 in regenerating peripheral nerve. Results We studied axonal regeneration in the PNS and CNS of genetically engineered mice that do not express NG2, and in sex and age matched wild-type controls. In the CNS, we used anterograde tracing with BDA to study corticospinal tract (CST axons after spinal cord injury and transganglionic labelling with CT-HRP to trace ascending sensory dorsal column (DC axons after DC lesions and a conditioning lesion of the sciatic nerve. Injury to these fibre tracts resulted in no difference between knockout and wild-type mice in the ability of CST axons or DC axons to enter or cross the lesion site. Similarly, after dorsal root injury (with conditioning lesion, most regenerating dorsal root axons failed to grow across the dorsal root entry zone in both transgenic and wild-type mice. Following sciatic nerve injuries, functional recovery was assessed by analysis of the toe-spreading reflex and cutaneous sensitivity to Von Frey hairs. Anatomical correlates of regeneration were assessed by: retrograde labelling of regenerating dorsal root ganglion (DRG cells with DiAsp; immunostaining with PGP 9.5 to visualise sensory reinnervation of plantar hindpaws; electron microscopic analysis of regenerating axons in tibial and digital nerves; and by silver-cholinesterase histochemical study of motor end plate reinnervation. We also examined functional and anatomical correlates of regeneration after injury of the facial nerve by assessing the time taken for whisker movements and corneal reflexes to recover and by retrograde labelling of regenerated axons with Fluorogold and DiAsp. None of the anatomical or functional analyses

  9. Axon density and axon orientation dispersion in children born preterm

    NARCIS (Netherlands)

    Kelly, Claire E.; Thompson, Deanne K.; Chen, Jian; Leemans, Alexander; Adamson, Christopher L.; Inder, Terrie E.; Cheong, Jeanie L Y; Doyle, Lex W.; Anderson, Peter J.

    2016-01-01

    Background Very preterm birth (VPT, <32 weeks' gestation) is associated with altered white matter fractional anisotropy (FA), the biological basis of which is uncertain but may relate to changes in axon density and/or dispersion, which can be measured using Neurite Orientation Dispersion and Density

  10. Axon damage and repair in multiple sclerosis.

    OpenAIRE

    Perry, V.H.; Anthony, D. C.

    1999-01-01

    It is well known that within long-standing multiple sclerosis (MS) lesions there is axonal loss but whether it is an early or late event has been more difficult to establish. The use of immunocytochemical methods that reveal axonal end-bulbs is a valuable approach to investigating acute axonal injury in human pathological material. The application of these techniques to multiple sclerosis tissue reveals evidence of axonal injury in acute lesions; the distribution of the end-bulbs in acute and...

  11. Single-particle tracking uncovers dynamics of glutamate-induced retrograde transport of NF-κB p65 in living neurons.

    Science.gov (United States)

    Widera, Darius; Klenke, Christin; Nair, Deepak; Heidbreder, Meike; Malkusch, Sebastian; Sibarita, Jean-Baptiste; Choquet, Daniel; Kaltschmidt, Barbara; Heilemann, Mike; Kaltschmidt, Christian

    2016-10-01

    Retrograde transport of NF-κB from the synapse to the nucleus in neurons is mediated by the dynein/dynactin motor complex and can be triggered by synaptic activation. The caliber of axons is highly variable ranging down to 100 nm, aggravating the investigation of transport processes in neurites of living neurons using conventional light microscopy. We quantified for the first time the transport of the NF-κB subunit p65 using high-density single-particle tracking in combination with photoactivatable fluorescent proteins in living mouse hippocampal neurons. We detected an increase of the mean diffusion coefficient ([Formula: see text]) in neurites from [Formula: see text] to [Formula: see text] after stimulation with glutamate. We further observed that the relative amount of retrogradely transported p65 molecules is increased after stimulation. Glutamate treatment resulted in an increase of the mean retrograde velocity from [Formula: see text] to [Formula: see text], whereas a velocity increase from [Formula: see text] to [Formula: see text] was observed for anterogradely transported p65. This study demonstrates for the first time that glutamate stimulation leads to an increased mobility of single NF-κB p65 molecules in neurites of living hippocampal neurons. PMID:27226975

  12. Plasminogen deficiency causes reduced corticospinal axonal plasticity and functional recovery after stroke in mice.

    Directory of Open Access Journals (Sweden)

    Zhongwu Liu

    Full Text Available Tissue plasminogen activator (tPA has been implicated in neurite outgrowth and neurological recovery post stroke. tPA converts the zymogen plasminogen (Plg into plasmin. In this study, using plasminogen knockout (Plg-/- mice and their Plg-native littermates (Plg+/+, we investigated the role of Plg in axonal remodeling and neurological recovery after stroke. Plg+/+ and Plg-/- mice (n = 10/group were subjected to permanent intraluminal monofilament middle cerebral artery occlusion (MCAo. A foot-fault test and a single pellet reaching test were performed prior to and on day 3 after stroke, and weekly thereafter to monitor functional deficit and recovery. Biotinylated dextran amine (BDA was injected into the left motor cortex to anterogradely label the corticospinal tract (CST. Animals were euthanized 4 weeks after stroke. Neurite outgrowth was also measured in primary cultured cortical neurons harvested from Plg+/+ and Plg-/- embryos. In Plg+/+ mice, the motor functional deficiency after stroke progressively recovered with time. In contrast, recovery in Plg-/- mice was significantly impaired compared to Plg+/+ mice (p0.82, p<0.01. Plg-/- neurons exhibited significantly reduced neurite outgrowth. Our data suggest that plasminogen-dependent proteolysis has a beneficial effect during neurological recovery after stroke, at least in part, by promoting axonal remodeling in the denervated spinal cord.

  13. Anterograde transneuronal viral tract tracing reveals central sensory circuits from brown fat and sensory denervation alters its thermogenic responses

    OpenAIRE

    Vaughan, Cheryl H.; Bartness, Timothy J.

    2012-01-01

    Brown adipose tissue (BAT) thermogenic activity and growth are controlled by its sympathetic nervous system (SNS) innervation, but nerve fibers containing sensory-associated neuropeptides [substance P, calcitonin gene-related peptide (CGRP)] also suggest sensory innervation. The central nervous system (CNS) projections of BAT afferents are unknown. Therefore, we used the H129 strain of the herpes simplex virus-1 (HSV-1), an anterograde transneuronal viral tract tracer used to delineate sensor...

  14. Anterograde or Retrograde Transsynaptic Circuit Tracing in Vertebrates with Vesicular Stomatitis Virus Vectors.

    Science.gov (United States)

    Beier, Kevin T; Mundell, Nathan A; Pan, Y Albert; Cepko, Constance L

    2016-01-01

    Viruses have been used as transsynaptic tracers, allowing one to map the inputs and outputs of neuronal populations, due to their ability to replicate in neurons and transmit in vivo only across synaptically connected cells. To date, their use has been largely restricted to mammals. In order to explore the use of such viruses in an expanded host range, we tested the transsynaptic tracing ability of recombinant vesicular stomatitis virus (rVSV) vectors in a variety of organisms. Successful infection and gene expression were achieved in a wide range of organisms, including vertebrate and invertebrate model organisms. Moreover, rVSV enabled transsynaptic tracing of neural circuitry in predictable directions dictated by the viral envelope glycoprotein (G), derived from either VSV or rabies virus (RABV). Anterograde and retrograde labeling, from initial infection and/or viral replication and transmission, was observed in Old and New World monkeys, seahorses, jellyfish, zebrafish, chickens, and mice. These vectors are widely applicable for gene delivery, afferent tract tracing, and/or directional connectivity mapping. Here, we detail the use of these vectors and provide protocols for propagating virus, changing the surface glycoprotein, and infecting multiple organisms using several injection strategies. PMID:26729030

  15. Retrosplenial Cortical Contributions to Anterograde and Retrograde Memory in the Monkey.

    Science.gov (United States)

    Buckley, Mark J; Mitchell, Anna S

    2016-06-01

    Primate retrosplenial cortex (RSC) is important for memory but patient neuropathologies are diffuse so its key contributions to memory remain elusive. This study provides the first causal evidence that RSC in macaque monkeys is crucial for postoperative retention of preoperatively and postoperatively acquired memories. Preoperatively, monkeys learned 300 object-in-place scene discriminations across sessions. After RSC removal, one-trial postoperative retention tests revealed significant retrograde memory loss for these 300 discriminations relative to unoperated control monkeys. Less robust evidence was found for a deficit in anterograde memory (new postoperative learning) after RSC lesions as new learning to criterion measures failed to reveal any significant learning impairment. However, after achieving ≥90% learning criterion for the postoperatively presented novel 100 object-in-place scene discriminations, short-term retention (i.e., measured after 24 h delay) of this well-learnt set was impaired in the RSC monkeys relative to controls. A further experiment assessed rapid "within" session acquisition of novel object-in-place scene discriminations, again confirming that new learning per se was unimpaired by bilateral RSC removal. Primate RSC contributes critically to memory by supporting normal retention of information, even when this information does not involve an autobiographical component. PMID:26946129

  16. Human intraretinal myelination: Axon diameters and axon/myelin thickness ratios

    Science.gov (United States)

    FitzGibbon, Thomas; Nestorovski, Zoran

    2013-01-01

    Purpose: Human intraretinal myelination of ganglion cell axons occurs in about 1% of the population. We examined myelin thickness and axon diameter in human retinal specimens containing myelinated retinal ganglion cell axons. Materials and Methods: Two eyes containing myelinated patches were prepared for electron microscopy. Two areas were examined in one retina and five in the second retina. Measurements were compared to normal retinal and optic nerve samples and the rabbit retina, which normally contains myelinated axons. Measurements were made using a graphics tablet. Results: Mean axon diameter of myelinated axons at all locations were significantly larger than unmyelinated axons (P ≤ 0.01). Myelinated axons within the patches were significantly larger than axons within the optic nerve (P < 0.01). The relationship between axon diameter/fiber diameter (the G-ratio) seen in the retinal sites differed from that in the nerve. G-ratios were higher and myelin thickness was positively correlated to axon diameter (P < 0.01) in the retina but negatively correlated to axon diameter in the nerve (P < 0.001). Conclusion: Intraretinally myelinated axons are larger than non-myelinated axons from the same population and suggests that glial cells can induce diameter changes in retinal axons that are not normally myelinated. This effect is more dramatic on intraretinal axons compared with the normal transition zone as axons enter the optic nerve and these changes are abnormal. Whether intraretinal myelin alters axonal conduction velocity or blocks axonal conduction remains to be clarified and these issues may have different clinical outcomes. PMID:24212308

  17. Local protein synthesis in neuronal axons: why and how we study

    OpenAIRE

    Kim, Eunjin; Jung, Hosung

    2015-01-01

    Adaptive brain function and synaptic plasticity rely on dynamic regulation of local proteome. One way for the neuron to introduce new proteins to the axon terminal is to transport those from the cell body, which had long been thought as the only source of axonal proteins. Another way, which is the topic of this review, is synthesizing proteins on site by local mRNA translation. Recent evidence indicates that the axon stores a reservoir of translationally silent mRNAs and regulates their expre...

  18. Quantifying mechanical force in axonal growth and guidance

    Directory of Open Access Journals (Sweden)

    Ahmad Ibrahim Mahmoud Athamneh

    2015-09-01

    Full Text Available Mechanical force plays a fundamental role in neuronal development, physiology, and regeneration. In particular, research has shown that force is involved in growth cone-mediated axonal growth and guidance as well as stretch-induced elongation when an organism increases in size after forming initial synaptic connections. However, much of the details about the exact role of force in these fundamental processes remain unknown. In this review, we highlight (1 standing questions concerning the role of mechanical force in axonal growth and guidance and (2 different experimental techniques used to quantify forces in axons and growth cones. We believe that satisfying answers to these questions will require quantitative information about the relationship between elongation, forces, cytoskeletal dynamics, axonal transport, signaling, substrate adhesion, and stiffness contributing to directional growth advance. Furthermore, we address why a wide range of force values have been reported in the literature, and what these values mean in the context of neuronal mechanics. We hope that this review will provide a guide for those interested in studying the role of force in development and regeneration of neuronal networks.

  19. Early phenotype expression of cortical neurons: evidence that a subclass of migrating neurons have callosal axons.

    OpenAIRE

    Schwartz, M. L.; Rakic, P.; Goldman-Rakic, P. S.

    1991-01-01

    The use of [3H]thymidine labeling in combination with various axonal transport tracers has revealed that a subset of migrating neurons in the fetal monkey cerebrum issue axons to the opposite cerebral hemisphere while still migrating to their final positions in the cortical plate. Other cortical neurons with the same "birthdate" (i.e., that underwent their last round of DNA synthesis on the same day) are not retrogradely labeled by tracer injections of the opposite hemisphere. These findings ...

  20. Precursor and mature NGF live tracking: one versus many at a time in the axons.

    Science.gov (United States)

    De Nadai, Teresa; Marchetti, Laura; Di Rienzo, Carmine; Calvello, Mariantonietta; Signore, Giovanni; Di Matteo, Pierluigi; Gobbo, Francesco; Turturro, Sabrina; Meucci, Sandro; Viegi, Alessandro; Beltram, Fabio; Luin, Stefano; Cattaneo, Antonino

    2016-01-01

    The classical view of nerve growth factor (NGF) action in the nervous system is linked to its retrograde axonal transport. However, almost nothing is known on the trafficking properties of its unprocessed precursor proNGF, characterized by different and generally opposite biological functions with respect to its mature counterpart. Here we developed a strategy to fluorolabel both purified precursor and mature neurotrophins (NTs) with a controlled stoichiometry and insertion site. Using a single particle tracking approach, we characterized the axonal transport of proNGF versus mature NGF in living dorsal root ganglion neurons grown in compartmentalized microfluidic devices. We demonstrate that proNGF is retrogradely transported as NGF, but with a lower flux and a different distribution of numbers of neurotrophins per vesicle. Moreover, exploiting a dual-color labelling technique, we analysed the transport of both NT forms when simultaneously administered to the axon tips. PMID:26829890

  1. Axon degeneration and PGC-1α-mediated protection in a zebrafish model of α-synuclein toxicity

    Directory of Open Access Journals (Sweden)

    Kelley C. O’Donnell

    2014-05-01

    Full Text Available α-synuclein (aSyn expression is implicated in neurodegenerative processes, including Parkinson’s disease (PD and dementia with Lewy bodies (DLB. In animal models of these diseases, axon pathology often precedes cell death, raising the question of whether aSyn has compartment-specific toxic effects that could require early and/or independent therapeutic intervention. The relevance of axonal pathology to degeneration can only be addressed through longitudinal, in vivo monitoring of different neuronal compartments. With current imaging methods, dopaminergic neurons do not readily lend themselves to such a task in any vertebrate system. We therefore expressed human wild-type aSyn in zebrafish peripheral sensory neurons, which project elaborate superficial axons that can be continuously imaged in vivo. Axonal outgrowth was normal in these neurons but, by 2 days post-fertilization (dpf, many aSyn-expressing axons became dystrophic, with focal varicosities or diffuse beading. Approximately 20% of aSyn-expressing cells died by 3 dpf. Time-lapse imaging revealed that focal axonal swelling, but not overt fragmentation, usually preceded cell death. Co-expressing aSyn with a mitochondrial reporter revealed deficits in mitochondrial transport and morphology even when axons appeared overtly normal. The axon-protective protein Wallerian degeneration slow (WldS delayed axon degeneration but not cell death caused by aSyn. By contrast, the transcriptional coactivator PGC-1α, which has roles in the regulation of mitochondrial biogenesis and reactive-oxygen-species detoxification, abrogated aSyn toxicity in both the axon and the cell body. The rapid onset of axonal pathology in this system, and the relatively moderate degree of cell death, provide a new model for the study of aSyn toxicity and protection. Moreover, the accessibility of peripheral sensory axons will allow effects of aSyn to be studied in different neuronal compartments and might have utility in

  2. AxonSeg: Open Source Software for Axon and Myelin Segmentation and Morphometric Analysis.

    Science.gov (United States)

    Zaimi, Aldo; Duval, Tanguy; Gasecka, Alicja; Côté, Daniel; Stikov, Nikola; Cohen-Adad, Julien

    2016-01-01

    Segmenting axon and myelin from microscopic images is relevant for studying the peripheral and central nervous system and for validating new MRI techniques that aim at quantifying tissue microstructure. While several software packages have been proposed, their interface is sometimes limited and/or they are designed to work with a specific modality (e.g., scanning electron microscopy (SEM) only). Here we introduce AxonSeg, which allows to perform automatic axon and myelin segmentation on histology images, and to extract relevant morphometric information, such as axon diameter distribution, axon density and the myelin g-ratio. AxonSeg includes a simple and intuitive MATLAB-based graphical user interface (GUI) and can easily be adapted to a variety of imaging modalities. The main steps of AxonSeg consist of: (i) image pre-processing; (ii) pre-segmentation of axons over a cropped image and discriminant analysis (DA) to select the best parameters based on axon shape and intensity information; (iii) automatic axon and myelin segmentation over the full image; and (iv) atlas-based statistics to extract morphometric information. Segmentation results from standard optical microscopy (OM), SEM and coherent anti-Stokes Raman scattering (CARS) microscopy are presented, along with validation against manual segmentations. Being fully-automatic after a quick manual intervention on a cropped image, we believe AxonSeg will be useful to researchers interested in large throughput histology. AxonSeg is open source and freely available at: https://github.com/neuropoly/axonseg. PMID:27594833

  3. Axonal regeneration through arterial grafts.

    OpenAIRE

    Anderson, P. N.; Turmaine, M.

    1986-01-01

    The left common peroneal nerves of adult inbred mice were severed and allowed to regenerate through the lumina of Y-shaped tubes comprising grafts of abdominal aorta and its bifurcation. Very little regeneration took place within the grafts unless the distal nerve stump was inserted into one limb of the Y-tube. Using syngeneic grafts virtually all the axons regenerating through the lumen grew down the limb of the Y-tube containing the distal nerve. Using non-syngeneic grafts, however, a subst...

  4. Axonal interferon responses and alphaherpesvirus neuroinvasion

    Science.gov (United States)

    Song, Ren

    Infection by alphaherpesviruses, including herpes simplex virus (HSV) and pseudorabies virus (PRV), typically begins at a peripheral epithelial surface and continues into the peripheral nervous system (PNS) that innervates this tissue. Inflammatory responses are induced at the infected peripheral site prior to viral invasion of the PNS. PNS neurons are highly polarized cells with long axonal processes that connect to distant targets. When the peripheral tissue is first infected, only the innervating axons are exposed to this inflammatory milieu, which include type I interferon (e.g. IFNbeta) and type II interferon (i.e. IFNgamma). IFNbeta can be produced by all types of cells, while IFNgamma is secreted by some specific types of immune cells. And both types of IFN induce antiviral responses in surrounding cells that express the IFN receptors. The fundamental question is how do PNS neurons respond to the inflammatory milieu experienced only by their axons. Axons must act as potential front-line barriers to prevent PNS infection and damage. Using compartmented cultures that physically separate neuron axons from cell bodies, I found that pretreating isolated axons with IFNbeta or IFNgamma significantly diminished the number of HSV-1 and PRV particles moving from axons to the cell bodies in an IFN receptor-dependent manner. Furthermore, I found the responses in axons are activated differentially by the two types of IFNs. The response to IFNbeta is a rapid, axon-only response, while the response to IFNgamma involves long distance signaling to the PNS cell body. For example, exposing axons to IFNbeta induced STAT1 phosphorylation (p-STAT1) only in axons, while exposure of axons to IFNgamma induced p-STAT1 accumulation in distant cell body nuclei. Blocking transcription in cell bodies eliminated IFNgamma-, but not IFNbeta-mediated antiviral effects. Proteomic analysis of IFNbeta- or IFNgamma-treated axons identified several differentially regulated proteins. Therefore

  5. Abnormal growth of the corticospinal axons into the lumbar spinal cord of the hyt/hyt mouse with congenital hypothyroidism.

    Science.gov (United States)

    Hsu, Jung-Yu C; Stein, Stuart A; Xu, Xiao-Ming

    2008-11-01

    Thyroid hormone deficiency may cause severe neurological disorders resulting from developmental deficits of the central nervous system. The mutant hyt/hyt mouse, characterized by fetal-onset, life-long hypothyroidism resulting from a point mutation of the thyroid-stimulating hormone receptor of the thyroid gland, displays a variety of abnormalities in motor behavior that are likely associated with dysfunctions of specific brain regions and a defective corticospinal tract (CST). To test the hypothesis that fetal and neonatal hypothyroidism cause abnormal CST development, the growth of the CST was investigated in hypothyroid hyt/hyt mice and their euthyroid progenitors, the BALB/cByJ mice. Anterograde labeling with biotinylated dextran amine demonstrated a decrease in the number of CST axons in the hyt/hyt mouse at the first lumbar level at postnatal day (P) 10. After retrograde tracing with fast blue (FB), fewer FB-labeled neurons were found in the motor cortex, the red nucleus, and the lateral vestibular nucleus of the hyt/hyt mouse. At the fourth lumbar level, the hyt/hyt mouse also showed smaller CST cross-sectional areas and significantly lower numbers of unmyelinated axons, myelinated axons, and growth cones within the CST during postnatal development. At P10, the hyt/hyt mouse demonstrated significantly lower immunoreactivity of embryonic neural cell adhesion molecule in the CST at the seventh cervical level, whereas the expression of growth-associated protein 43 remained unchanged. Our study demonstrated an abnormal development of the CST in the hyt/hyt mouse, manifested by reduced axon quantity and retarded growth pattern at the lumbar spinal cord. PMID:18543337

  6. Uptake of nerve growth factor along peripheral and spinal axons of primary sensory neurons

    International Nuclear Information System (INIS)

    To investigate the distribution of nerve growth factor (NGF) receptors on peripheral and central axons, [125I]NGF was injected into the sciatic nerve or spinal cord of adult rats. Accumulation of [125I]NGF in lumbar dorsal root ganglia was monitored by gamma emission counting and radioautography. [125I]NGF, injected endoneurially in small quantities, was taken into sensory axons by a saturable process and was transported retrogradely to their cell bodies at a maximal rate of 2.5 to 7.5 mm/hr. Because very little [125I]NGF reached peripheral terminals, the results were interpreted to indicate that receptors for NGF are present on nonterminal segments of sensory axons. The specificity and high affinity of NGF uptake were illustrated by observations that negligible amounts of gamma activity accumulated in lumbar dorsal root ganglia after comparable intraneural injection of [125I] cytochrome C or [125I]oxidized NGF. Similar techniques were used to demonstrate avid internalization and retrograde transport of [125I]NGF by intraspinal axons arising from dorsal root ganglia. Following injection of [125I]NGF into lumbar or cervical regions of the spinal cord, neuronal perikarya were clearly labeled in radioautographs of lumbar dorsal root ganglia. Sites for NGF uptake on primary sensory neurons in the adult rat are not restricted to peripheral axon terminals but are extensively distributed along both peripheral and central axons. Receptors on axons provide a mechanism whereby NGF supplied by glia could influence neuronal maintenance or axonal regeneration

  7. Axon reflexes in human cold exposed fingers

    NARCIS (Netherlands)

    Daanen, H.A.M.; Ducharme, M.B.

    2000-01-01

    Exposure of fingers to severe cold induces cold induced vasodilation (CIVD). The mechanism of CIVD is still debated. The original theory states that an axon reflex causes CIVD. To test this hypothesis, axon reflexes were evoked by electrical stimulation of the middle fingers of hands immersed in wat

  8. Cable energy function of cortical axons.

    Science.gov (United States)

    Ju, Huiwen; Hines, Michael L; Yu, Yuguo

    2016-01-01

    Accurate estimation of action potential (AP)-related metabolic cost is essential for understanding energetic constraints on brain connections and signaling processes. Most previous energy estimates of the AP were obtained using the Na(+)-counting method, which seriously limits accurate assessment of metabolic cost of ionic currents that underlie AP conduction along the axon. Here, we first derive a full cable energy function for cortical axons based on classic Hodgkin-Huxley (HH) neuronal equations and then apply the cable energy function to precisely estimate the energy consumption of AP conduction along axons with different geometric shapes. Our analytical approach predicts an inhomogeneous distribution of metabolic cost along an axon with either uniformly or nonuniformly distributed ion channels. The results show that the Na(+)-counting method severely underestimates energy cost in the cable model by 20-70%. AP propagation along axons that differ in length may require over 15% more energy per unit of axon area than that required by a point model. However, actual energy cost can vary greatly depending on axonal branching complexity, ion channel density distributions, and AP conduction states. We also infer that the metabolic rate (i.e. energy consumption rate) of cortical axonal branches as a function of spatial volume exhibits a 3/4 power law relationship. PMID:27439954

  9. Cable energy function of cortical axons

    Science.gov (United States)

    Ju, Huiwen; Hines, Michael L.; Yu, Yuguo

    2016-01-01

    Accurate estimation of action potential (AP)-related metabolic cost is essential for understanding energetic constraints on brain connections and signaling processes. Most previous energy estimates of the AP were obtained using the Na+-counting method, which seriously limits accurate assessment of metabolic cost of ionic currents that underlie AP conduction along the axon. Here, we first derive a full cable energy function for cortical axons based on classic Hodgkin-Huxley (HH) neuronal equations and then apply the cable energy function to precisely estimate the energy consumption of AP conduction along axons with different geometric shapes. Our analytical approach predicts an inhomogeneous distribution of metabolic cost along an axon with either uniformly or nonuniformly distributed ion channels. The results show that the Na+-counting method severely underestimates energy cost in the cable model by 20–70%. AP propagation along axons that differ in length may require over 15% more energy per unit of axon area than that required by a point model. However, actual energy cost can vary greatly depending on axonal branching complexity, ion channel density distributions, and AP conduction states. We also infer that the metabolic rate (i.e. energy consumption rate) of cortical axonal branches as a function of spatial volume exhibits a 3/4 power law relationship. PMID:27439954

  10. Neuronal Development: SAD Kinases Make Happy Axons

    OpenAIRE

    Xing, Lei; Newbern, Jason M.; Snider, William D

    2013-01-01

    The polarity proteins LKB1 and SAD-A/B are key regulators of axon specification in the developing cerebral cortex. Recent studies now show that this mechanism cannot be generalized to other classes of neurons: instead, SAD-A/B functions downstream of neurotrophin signaling in sensory neurons to mediate a later stage of axon development — arborization in the target field.

  11. Early events in axon/dendrite polarization.

    Science.gov (United States)

    Cheng, Pei-lin; Poo, Mu-ming

    2012-01-01

    Differentiation of axons and dendrites is a critical step in neuronal development. Here we review the evidence that axon/dendrite formation during neuronal polarization depends on the intrinsic cytoplasmic asymmetry inherited by the postmitotic neuron, the exposure of the neuron to extracellular chemical factors, and the action of anisotropic mechanical forces imposed by the environment. To better delineate the functions of early signals among a myriad of cellular components that were shown to influence axon/dendrite formation, we discuss their functions by distinguishing their roles as determinants, mediators, or modulators and consider selective degradation of these components as a potential mechanism for axon/dendrite polarization. Finally, we examine whether these early events of axon/dendrite formation involve local autocatalytic activation and long-range inhibition, as postulated by Alan Turing for the morphogenesis of patterned biological structure. PMID:22715881

  12. SNTF immunostaining reveals previously undetected axonal pathology in traumatic brain injury.

    Science.gov (United States)

    Johnson, Victoria E; Stewart, William; Weber, Maura T; Cullen, D Kacy; Siman, Robert; Smith, Douglas H

    2016-01-01

    Diffuse axonal injury (DAI) is a common feature of severe traumatic brain injury (TBI) and may also be a predominant pathology in mild TBI or "concussion". The rapid deformation of white matter at the instant of trauma can lead to mechanical failure and calcium-dependent proteolysis of the axonal cytoskeleton in association with axonal transport interruption. Recently, a proteolytic fragment of alpha-II spectrin, "SNTF", was detected in serum acutely following mild TBI in patients and was prognostic for poor clinical outcome. However, direct evidence that this fragment is a marker of DAI has yet to be demonstrated in either humans following TBI or in models of mild TBI. Here, we used immunohistochemistry (IHC) to examine for SNTF in brain tissue following both severe and mild TBI. Human severe TBI cases (survival <7d; n = 18) were compared to age-matched controls (n = 16) from the Glasgow TBI archive. We also examined brains from an established model of mild TBI at 6, 48 and 72 h post-injury versus shams. IHC specific for SNTF was compared to that of amyloid precursor protein (APP), the current standard for DAI diagnosis, and other known markers of axonal pathology including non-phosphorylated neurofilament-H (SMI-32), neurofilament-68 (NF-68) and compacted neurofilament-medium (RMO-14) using double and triple immunofluorescent labeling. Supporting its use as a biomarker of DAI, SNTF immunoreactive axons were observed at all time points following both human severe TBI and in the model of mild TBI. Interestingly, SNTF revealed a subpopulation of degenerating axons, undetected by the gold-standard marker of transport interruption, APP. While there was greater axonal co-localization between SNTF and APP after severe TBI in humans, a subset of SNTF positive axons displayed no APP accumulation. Notably, some co-localization was observed between SNTF and the less abundant neurofilament subtype markers. Other SNTF positive axons, however, did not co-localize with any

  13. Dysregulated axonal RNA translation in amyotrophic lateral sclerosis.

    Science.gov (United States)

    Yasuda, Kyota; Mili, Stavroula

    2016-09-01

    Amyotrophic lateral sclerosis (ALS) is an adult-onset motor neuron disease that has been associated with a diverse array of genetic changes. Prominent among these are mutations in RNA-binding proteins (RBPs) or repeat expansions that give rise to toxic RNA species. RBPs are additionally central components of pathologic aggregates that constitute a disease hallmark, suggesting that dysregulation of RNA metabolism underlies disease progression. In the context of neuronal physiology, transport of RNAs and localized RNA translation in axons are fundamental to neuronal survival and function. Several lines of evidence suggest that axonal RNA translation is a central process perturbed by various pathogenic events associated with ALS. Dysregulated translation of specific RNA groups could underlie feedback effects that connect and reinforce disease manifestations. Among such candidates are RNAs encoding proteins involved in the regulation of microtubule dynamics. Further understanding of axonally dysregulated RNA targets and of the feedback mechanisms they induce could provide useful therapeutic insights. WIREs RNA 2016, 7:589-603. doi: 10.1002/wrna.1352 For further resources related to this article, please visit the WIREs website. PMID:27038103

  14. Extra-neurohypophyseal axonal projections from individual vasopressin-containing magnocellular neurons in rat hypothalamus

    Directory of Open Access Journals (Sweden)

    Fernando Jauregui Huerta

    2015-10-01

    Full Text Available Conventional neuroanatomical, immunohistochemical techniques and electrophysiological recording, as well as in vitro labeling methods may fail to detect long range extra-neurohypophyseal-projecting axons from vasopressin (AVP-containing magnocellular neurons (magnocells in the hypothalamic paraventricular nucleus (PVN. Here, we used in vivo extracellular recording, juxtacellular labeling, post hoc anatomo-immunohistochemical analysis and camera lucida reconstruction to address this question. We demonstrate that all well-labeled AVP immunopositive neurons inside the PVN possess main axons joining the tract of Greving and multi-axon-like processes, as well as axonal collaterals branching very near to the somata, which project to extra-neurohypophyseal regions. The detected regions in this study include the medial and lateral preoptical area, suprachiasmatic nucleus, lateral habenula, medial and central amygdala and the conducting systems, such as stria medullaris, the fornix and the internal capsule. Expression of vesicular glutamate transporter 2 was observed in axon-collaterals. These results, in congruency with several previous reports in the literature, provided unequivocal evidence that AVP magnocells have an uncommon feature of possessing multiple axon-like processes emanating from somata or proximal dendrites. Furthermore, the long-range non-neurohypophyseal projections are more common than an “occasional” phenomenon as previously thought.

  15. Endoplasmic reticulum sorting and kinesin-1 command the targeting of axonal GABAB receptors.

    Directory of Open Access Journals (Sweden)

    Viviana Valdés

    Full Text Available In neuronal cells the intracellular trafficking machinery controls the availability of neurotransmitter receptors at the plasma membrane, which is a critical determinant of synaptic strength. Metabotropic γ amino-butyric acid (GABA type B receptors (GABA(BRs are neurotransmitter receptors that modulate synaptic transmission by mediating the slow and prolonged responses to GABA. GABA(BRs are obligatory heteromers constituted by two subunits, GABA(BR1 and GABA(BR2. GABA(BR1a and GABA(BR1b are the most abundant subunit variants. GABA(BR1b is located in the somatodendritic domain whereas GABA(BR1a is additionally targeted to the axon. Sushi domains located at the N-terminus of GABA(BR1a constitute the only difference between both variants and are necessary and sufficient for axonal targeting. The precise targeting machinery and the organelles involved in sorting and transport have not been described. Here we demonstrate that GABA(BRs require the Golgi apparatus for plasma membrane delivery but that axonal sorting and targeting of GABA(BR1a operate in a pre-Golgi compartment. In the axon GABA(BR1a subunits are enriched in the endoplasmic reticulum (ER, and their dynamic behavior and colocalization with other secretory organelles like the ER-to-Golgi intermediate compartment (ERGIC suggest that they employ a local secretory route. The transport of axonal GABA(BR1a is microtubule-dependent and kinesin-1, a molecular motor of the kinesin family, determines axonal localization. Considering that progression of GABA(BRs through the secretory pathway is regulated by an ER retention motif our data contribute to understand the role of the axonal ER in non-canonical sorting and targeting of neurotransmitter receptors.

  16. Genetics Home Reference: giant axonal neuropathy

    Science.gov (United States)

    ... in giant axonal neuropathy: new insights into disease mechanisms. Muscle Nerve. 2012 Aug;46(2):246-56. ... with a qualified healthcare professional . About Genetics Home Reference Site Map Contact Us Selection Criteria for Links ...

  17. Distribution of Mesenchymal Stem Cells and Effects on Neuronal Survival and Axon Regeneration after Optic Nerve Crush and Cell Therapy

    Science.gov (United States)

    Mesentier-Louro, Louise Alessandra; Zaverucha-do-Valle, Camila; da Silva-Junior, Almir Jordão; Nascimento-dos-Santos, Gabriel; Gubert, Fernanda; de Figueirêdo, Ana Beatriz Padilha; Torres, Ana Luiza; Paredes, Bruno D.; Teixeira, Camila; Tovar-Moll, Fernanda; Mendez-Otero, Rosalia; Santiago, Marcelo F.

    2014-01-01

    Bone marrow-derived cells have been used in different animal models of neurological diseases. We investigated the therapeutic potential of mesenchymal stem cells (MSC) injected into the vitreous body in a model of optic nerve injury. Adult (3–5 months old) Lister Hooded rats underwent unilateral optic nerve crush followed by injection of MSC or the vehicle into the vitreous body. Before they were injected, MSC were labeled with a fluorescent dye or with superparamagnetic iron oxide nanoparticles, which allowed us to track the cells in vivo by magnetic resonance imaging. Sixteen and 28 days after injury, the survival of retinal ganglion cells was evaluated by assessing the number of Tuj1- or Brn3a-positive cells in flat-mounted retinas, and optic nerve regeneration was investigated after anterograde labeling of the optic axons with cholera toxin B conjugated to Alexa 488. Transplanted MSC remained in the vitreous body and were found in the eye for several weeks. Cell therapy significantly increased the number of Tuj1- and Brn3a-positive cells in the retina and the number of axons distal to the crush site at 16 and 28 days after optic nerve crush, although the RGC number decreased over time. MSC therapy was associated with an increase in the FGF-2 expression in the retinal ganglion cells layer, suggesting a beneficial outcome mediated by trophic factors. Interleukin-1β expression was also increased by MSC transplantation. In summary, MSC protected RGC and stimulated axon regeneration after optic nerve crush. The long period when the transplanted cells remained in the eye may account for the effect observed. However, further studies are needed to overcome eventually undesirable consequences of MSC transplantation and to potentiate the beneficial ones in order to sustain the neuroprotective effect overtime. PMID:25347773

  18. Cat's medullary reticulospinal and subnucleus reticularis dorsalis noxious neurons form a coupled neural circuit through collaterals of descending axons.

    Science.gov (United States)

    Leiras, Roberto; Martín-Cora, Francisco; Velo, Patricia; Liste, Tania; Canedo, Antonio

    2016-01-01

    Animals and human beings sense and react to real/potential dangerous stimuli. However, the supraspinal mechanisms relating noxious sensing and nocifensive behavior are mostly unknown. The collateralization and spatial organization of interrelated neurons are important determinants of coordinated network function. Here we electrophysiologically studied medial medullary reticulospinal neurons (mMRF-RSNs) antidromically identified from the cervical cord of anesthetized cats and found that 1) more than 40% (79/183) of the sampled mMRF-RSNs emitted bifurcating axons running within the dorsolateral (DLF) and ventromedial (VMF) ipsilateral fascicles; 2) more than 50% (78/151) of the tested mMRF-RSNs with axons running in the VMF collateralized to the subnucleus reticularis dorsalis (SRD) that also sent ipsilateral descending fibers bifurcating within the DLF and the VMF. This percentage of mMRF collateralization to the SRD increased to more than 81% (53/65) when considering the subpopulation of mMRF-RSNs responsive to noxiously heating the skin; 3) reciprocal monosynaptic excitatory relationships were electrophysiologically demonstrated between noxious sensitive mMRF-RSNs and SRD cells; and 4) injection of the anterograde tracer Phaseolus vulgaris leucoagglutinin evidenced mMRF to SRD and SRD to mMRF projections contacting the soma and proximal dendrites. The data demonstrated a SRD-mMRF network interconnected mainly through collaterals of descending axons running within the VMF, with the subset of noxious sensitive cells forming a reverberating circuit probably amplifying mutual outputs simultaneously regulating motor activity and spinal noxious afferent input. The results provide evidence that noxious stimulation positively engages a reticular SRD-mMRF-SRD network involved in pain-sensory-to-motor transformation and modulation. PMID:26581870

  19. A retrograde apoptotic signal originating in NGF-deprived distal axons of rat sympathetic neurons in compartmented cultures

    Institute of Scientific and Technical Information of China (English)

    Sue-Ann Mok; Karen Lund; Robert B Campenot

    2009-01-01

    Previous investigations of retrograde survival signaling by nerve growth factor (NGF) and other neurotrophins have supported diverse mechanisms, but all proposed mechanisms have in common the generation of survival sig-nals retrogradely transmitted to the neuronal cell bodies. We report the finding of a retrograde apoptotic signal in axons that is suppressed by local NGF signaling. NGF withdrawal from distal axons alone was sufficient to activate the pro-apoptotic transcription factor, c-jnn, in the cell bodies. Providing NGF directly to cell bodies, thereby restor-ing a source of NGF-induced survival signals, could not prevent c-jun activation caused by NGF withdrawal from the distal axons. This is evidence that c-jun is not activated due to loss of survival signals at the cell bodies. Moreover, blocking axonal transport with colchicine inhibited c-jun activation caused by NGF deprivation suggesting that a retrogradely transported pro-apoptotic signal, rather than loss of a retrogradely transported survival signal, caused c-jun activation. Additional experiments showed that activation of c-jun, pro-caspase-3 cleavage, and apoptosis were blocked by the protein kinase C inhibitors, rottlerin and chelerythrine, only when applied to distal axons suggesting that they block the axon-specific pro-apoptotic signal. The rottlerin-sensitive mechanism was found to regulate glyco-gen synthase kinase 3 (GSK3) activity. The effect of siRNA knockdown, and pharmacological inhibition of GSK3 sug-gests that GSK3 is required for apoptosis caused by NGF deprivation and may function as a retrograde carrier of the axon apoptotic signal. The existence of a retrograde death signaling system in axons that is suppressed by neurotro-phins has broad implications for neurodevelopment and for discovering treatments for neurodegenerative diseases and neurotrauma.

  20. How Schwann Cells Sort Axons: New Concepts.

    Science.gov (United States)

    Feltri, M Laura; Poitelon, Yannick; Previtali, Stefano Carlo

    2016-06-01

    Peripheral nerves contain large myelinated and small unmyelinated (Remak) fibers that perform different functions. The choice to myelinate or not is dictated to Schwann cells by the axon itself, based on the amount of neuregulin I-type III exposed on its membrane. Peripheral axons are more important in determining the final myelination fate than central axons, and the implications for this difference in Schwann cells and oligodendrocytes are discussed. Interestingly, this choice is reversible during pathology, accounting for the remarkable plasticity of Schwann cells, and contributing to the regenerative potential of the peripheral nervous system. Radial sorting is the process by which Schwann cells choose larger axons to myelinate during development. This crucial morphogenetic step is a prerequisite for myelination and for differentiation of Remak fibers, and is arrested in human diseases due to mutations in genes coding for extracellular matrix and linkage molecules. In this review we will summarize progresses made in the last years by a flurry of reverse genetic experiments in mice and fish. This work revealed novel molecules that control radial sorting, and contributed unexpected ideas to our understanding of the cellular and molecular mechanisms that control radial sorting of axons. PMID:25686621

  1. Calpain activity promotes the sealing of severed giant axons

    OpenAIRE

    Godell, Christopher M.; Smyers, Mark E.; Eddleman, Christopher S.; Ballinger, Martis L.; Fishman, Harvey M.; Bittner, George D.

    1997-01-01

    A barrier (seal) must form at the cut ends of a severed axon if a neuron is to survive and eventually regenerate. Following severance of crayfish medial giant axons in physiological saline, vesicles accumulate at the cut end and form a barrier (seal) to ion and dye diffusion. In contrast, squid giant axons do not seal, even though injury-induced vesicles form after axonal transection and accumulate at cut axonal ends. Neither axon seals in Ca2+-free salines. The addition of calpain to the bat...

  2. Imaging axonal degeneration and repair in pre-clinical animal models of multiple sclerosis

    Directory of Open Access Journals (Sweden)

    Soumya S Yandamuri

    2016-05-01

    Full Text Available Multiple sclerosis (MS is a central nervous system (CNS disease characterized by chronic neuroinflammation, demyelination, and axonal damage. Infiltration of activated lymphocytes and myeloid cells are thought to be primarily responsible for white matter damage and axonopathy. Over time, this neurologic damage manifests clinically as debilitating motor and cognitive symptoms. Existing MS therapies focus on symptom relief and delay of disease progression through reduction of neuroinflammation. However, long-term strategies to remyelinate, protect, or regenerate axons have remained elusive, posing a challenge to treating progressive forms of MS. Preclinical mouse models and techniques such as immunohistochemistry, flow cytometry, and genomic and proteomic analysis have provided advances in our understanding of discrete time-points of pathology following disease induction. More recently, in vivo and in situ two-photon microscopy (2P has made it possible to visualize continuous real-time cellular behavior and structural changes occurring within the CNS during neuropathology. Research utilizing 2P imaging to study axonopathy in neuroinflammatory demyelinating disease has focused on five areas: (1 axonal morphologic changes (2 organelle transport and health, (3 relationship to inflammation, (4 neuronal excitotoxicity, and (5 regenerative therapies. 2P imaging may also be used to identify novel therapeutic targets via identification and clarification of dynamic cellular and molecular mechanisms of axonal regeneration and remyelination. Here, we review tools that have made 2P accessible for imaging neuropathologies and advances in our understanding of axonal degeneration and repair in preclinical models of demyelinating diseases.

  3. Microfluidic device for unidirectional axon growth

    Science.gov (United States)

    Malishev, E.; Pimashkin, A.; Gladkov, A.; Pigareva, Y.; Bukatin, A.; Kazantsev, V.; Mukhina, I.; Dubina, M.

    2015-11-01

    In order to better understand the communication and connectivity development of neuron networks, we designed microfluidic devices with several chambers for growing dissociated neuronal cultures from mice fetal hippocampus (E18). The chambers were connected with microchannels providing unidirectional axonal growth between “Source” and “Target” neural sub-networks. Experiments were performed in a hippocampal cultures plated in a poly-dimethylsiloxane (PDMS) microfluidic chip, aligned with a 60 microelectrode array (MEA). Axonal growth through microchannels was observed with brightfield, phase-contrast and fluorescence microscopy, and after 7 days in vitro electrical activity was recorded. Visual inspection and spike propagation analysis showed the predominant axonal growth in microchannels in a direction from “Source” to “Target”.

  4. Diverse modes of axon elaboration in the developing neocortex.

    Directory of Open Access Journals (Sweden)

    2005-08-01

    Full Text Available The development of axonal arbors is a critical step in the establishment of precise neural circuits, but relatively little is known about the mechanisms of axonal elaboration in the neocortex. We used in vivo two-photon time-lapse microscopy to image axons in the neocortex of green fluorescent protein-transgenic mice over the first 3 wk of postnatal development. This period spans the elaboration of thalamocortical (TC and Cajal-Retzius (CR axons and cortical synaptogenesis. Layer 1 collaterals of TC and CR axons were imaged repeatedly over time scales ranging from minutes up to days, and their growth and pruning were analyzed. The structure and dynamics of TC and CR axons differed profoundly. Branches of TC axons terminated in small, bulbous growth cones, while CR axon branch tips had large growth cones with numerous long filopodia. TC axons grew rapidly in straight paths, with frequent interstitial branch additions, while CR axons grew more slowly along tortuous paths. For both types of axon, new branches appeared at interstitial sites along the axon shaft and did not involve growth cone splitting. Pruning occurred via retraction of small axon branches (tens of microns, at both CR and TC axons or degeneration of large portions of the arbor (hundreds of microns, for TC axons only. The balance between growth and retraction favored overall growth, but only by a slight margin. Given the identical layer 1 territory upon which CR and TC axons grow, the differences in their structure and dynamics likely reflect distinct intrinsic growth programs for axons of long projection neurons versus local interneurons.

  5. Automated Axon Counting in Rodent Optic Nerve Sections with AxonJ

    Science.gov (United States)

    Zarei, Kasra; Scheetz, Todd E.; Christopher, Mark; Miller, Kathy; Hedberg-Buenz, Adam; Tandon, Anamika; Anderson, Michael G.; Fingert, John H.; Abràmoff, Michael David

    2016-01-01

    We have developed a publicly available tool, AxonJ, which quantifies the axons in optic nerve sections of rodents stained with paraphenylenediamine (PPD). In this study, we compare AxonJ’s performance to human experts on 100x and 40x images of optic nerve sections obtained from multiple strains of mice, including mice with defects relevant to glaucoma. AxonJ produced reliable axon counts with high sensitivity of 0.959 and high precision of 0.907, high repeatability of 0.95 when compared to a gold-standard of manual assessments and high correlation of 0.882 to the glaucoma damage staging of a previously published dataset. AxonJ allows analyses that are quantitative, consistent, fully-automated, parameter-free, and rapid on whole optic nerve sections at 40x. As a freely available ImageJ plugin that requires no highly specialized equipment to utilize, AxonJ represents a powerful new community resource augmenting studies of the optic nerve using mice. PMID:27226405

  6. MSC p43 required for axonal development in motor neurons

    Science.gov (United States)

    Zhu, Xiaodong; Liu, Yang; Yin, Yanqing; Shao, Aiyun; Zhang, Bo; Kim, Sunghoon; Zhou, Jiawei

    2009-01-01

    Neuron connectivity and correct neural function largely depend on axonal integrity. Neurofilaments (NFs) constitute the main cytoskeletal network maintaining the structural integrity of neurons and exhibit dynamic changes during axonal and dendritic growth. However, the mechanisms underlying axonal development and maintenance remain poorly understood. Here, we identify that multisynthetase complex p43 (MSC p43) is essential for NF assembly and axon maintenance. The MSC p43 protein was predominantly expressed in central neurons and interacted with NF light subunit in vivo. Mice lacking MSC p43 exhibited axon degeneration in motor neurons, defective neuromuscular junctions, muscular atrophy, and motor dysfunction. Furthermore, MSC p43 depletion in mice caused disorganization of the axonal NF network. Mechanistically, MSC p43 is required for maintaining normal phosphorylation levels of NFs. Thus, MSC p43 is indispensable in maintaining axonal integrity. Its dysfunction may underlie the NF disorganization and axon degeneration associated with motor neuron degenerative diseases. PMID:19717447

  7. APC binds the Miro/Milton motor complex to stimulate transport of mitochondria to the plasma membrane

    OpenAIRE

    Mills, Kate M.; Brocardo, Mariana G.; Henderson, Beric R.

    2016-01-01

    The role of adenomatous polyposis coli (APC) tumor suppressor at mitochondria is unclear. We show that APC associates with the Miro/Milton/kinesin complex to stimulate anterograde transport of mitochondria. This identifies the first regulatory role of APC in organelle transport. APC cancer mutations block this activity.

  8. Functions of axon guidance molecules in synapse formation

    OpenAIRE

    Chen, Shih-Yu; Cheng, Hwai-Jong

    2009-01-01

    Axon guidance and synapse formation are important developmental events for establishing a functional neuronal circuitry. These two related cellular processes occur in a coordinated fashion but previous studies from multiple model organisms seemed to suggest that axon guidance and synapse formation are mediated by distinct molecular cues. Thus, axon guidance molecules are responsible for guiding the navigating axon toward its target area, while other adhesion or ligand-receptor molecules speci...

  9. Morphometry of Axons in Optic Nerves of Siamese's Twins

    Institute of Scientific and Technical Information of China (English)

    Xinzu Gu; Zhenping Zhang; Qi Lin; Jiongji Liang; Wenyu Lu; Xiulan Ye; A A Sadun

    2002-01-01

    Purpose: To observe the development of optic nerve, we examined four optic nerves from Siameses Twins by absolute counts of axons.Methods: Mean axon diameter, mean axon density, totally axonal population and optic nerve area were noted for each optic nerve. The mean axon diameter and the mean axon density were compared between paraxial (inner sectors)and cortical (outer sectors)areas of the nerves.Results: More myelinated axons were seen in the inner sectors as compared to the outer sectors(average 11 axons/1 000 μm2 in inner sectors and 34 axons/l 000 μm2 in outer sectors( P=0. 036) . The myelinated fibers were also smaller(63 microns) in the outer sectors as compared to the inner sectors(72 microns) ( P = 0. 001 ). The average cross sectors area for the four 40 week stage optical nerves of Siamese Twins was 3.32 × 103 as compared to 1 million axons for 32-week-old normals.Conclusion: Our finding of fewer axonal number and small myelinated fibers in the Siamese Twins suggests hypoplasia. Myelination was more abnormal in the paraxial optic nerve than that in the peripheral sectors, suggesting anomalous development of optic nerve peripherally and delayed developnent centrally. Axonal density is higher in inner sectors than that in outer sectors, suggesting delayed development of the outer nerve sector.

  10. Electrokinetic confinement of axonal growth for dynamically configurable neural networks.

    Science.gov (United States)

    Honegger, Thibault; Scott, Mark A; Yanik, Mehmet F; Voldman, Joel

    2013-02-21

    Axons in the developing nervous system are directed via guidance cues, whose expression varies both spatially and temporally, to create functional neural circuits. Existing methods to create patterns of neural connectivity in vitro use only static geometries, and are unable to dynamically alter the guidance cues imparted on the cells. We introduce the use of AC electrokinetics to dynamically control axonal growth in cultured rat hippocampal neurons. We find that the application of modest voltages at frequencies on the order of 10(5) Hz can cause developing axons to be stopped adjacent to the electrodes while axons away from the electric fields exhibit uninhibited growth. By switching electrodes on or off, we can reversibly inhibit or permit axon passage across the electrodes. Our models suggest that dielectrophoresis is the causative AC electrokinetic effect. We make use of our dynamic control over axon elongation to create an axon-diode via an axon-lock system that consists of a pair of electrode 'gates' that either permit or prevent axons from passing through. Finally, we developed a neural circuit consisting of three populations of neurons, separated by three axon-locks to demonstrate the assembly of a functional, engineered neural network. Action potential recordings demonstrate that the AC electrokinetic effect does not harm axons, and Ca(2+) imaging demonstrated the unidirectional nature of the synaptic connections. AC electrokinetic confinement of axonal growth has potential for creating configurable, directional neural networks. PMID:23314575

  11. Spatial temperature gradients guide axonal outgrowth

    Science.gov (United States)

    Black, Bryan; Vishwakarma, Vivek; Dhakal, Kamal; Bhattarai, Samik; Pradhan, Prabhakar; Jain, Ankur; Kim, Young-Tae; Mohanty, Samarendra

    2016-07-01

    Formation of neural networks during development and regeneration after injury depends on accuracy of axonal pathfinding, which is primarily believed to be influenced by chemical cues. Recently, there is growing evidence that physical cues can play crucial role in axonal guidance. However, detailed mechanism involved in such guidance cues is lacking. By using weakly-focused near-infrared continuous wave (CW) laser microbeam in the path of an advancing axon, we discovered that the beam acts as a repulsive guidance cue. Here, we report that this highly-effective at-a-distance guidance is the result of a temperature field produced by the near-infrared laser light absorption. Since light absorption by extracellular medium increases when the laser wavelength was red shifted, the threshold laser power for reliable guidance was significantly lower in the near-infrared as compared to the visible spectrum. The spatial temperature gradient caused by the near-infrared laser beam at-a-distance was found to activate temperature-sensitive membrane receptors, resulting in an influx of calcium. The repulsive guidance effect was significantly reduced when extracellular calcium was depleted or in the presence of TRPV1-antagonist. Further, direct heating using micro-heater confirmed that the axonal guidance is caused by shallow temperature-gradient, eliminating the role of any non-photothermal effects.

  12. Early cellular signaling responses to axonal injury

    Directory of Open Access Journals (Sweden)

    Wang Ai

    2009-03-01

    Full Text Available Abstract Background We have used optic nerve injury as a model to study early signaling events in neuronal tissue following axonal injury. Optic nerve injury results in the selective death of retinal ganglion cells (RGCs. The time course of cell death takes place over a period of days with the earliest detection of RGC death at about 48 hr post injury. We hypothesized that in the period immediately following axonal injury, there are changes in the soma that signal surrounding glia and neurons and that start programmed cell death. In the current study, we investigated early changes in cellular signaling and gene expression that occur within the first 6 hrs post optic nerve injury. Results We found evidence of cell to cell signaling within 30 min of axonal injury. We detected differences in phosphoproteins and gene expression within the 6 hrs time period. Activation of TNFα and glutamate receptors, two pathways that can initiate cell death, begins in RGCs within 6 hrs following axonal injury. Differential gene expression at 6 hrs post injury included genes involved in cytokine, neurotrophic factor signaling (Socs3 and apoptosis (Bax. Conclusion We interpret our studies to indicate that both neurons and glia in the retina have been signaled within 30 min after optic nerve injury. The signals are probably initiated by the RGC soma. In addition, signals activating cellular death pathways occur within 6 hrs of injury, which likely lead to RGC degeneration.

  13. Patterns of growth, axonal extension and axonal arborization of neuronal lineages in the developing Drosophila brain

    OpenAIRE

    Larsen, Camilla; Shy, Diana; Spindler, Shana R; Fung, Siaumin; Pereanu, Wayne; Younossi -Hartenstein, Amelia; Hartenstein, Volker

    2009-01-01

    The Drosophila central brain is composed of approximately 100 paired lineages, with most lineages comprising 100–150 neurons. Most lineages have a number of important characteristics in common. Typically, neurons of a lineage stay together as a coherent cluster and project their axons into a coherent bundle visible from late embryo to adult. Neurons born during the embryonic period form the primary axon tracts (PATs) that follow stereotyped pathways in the neuropile. Apoptotic cell death remo...

  14. A Novel High Content Imaging-Based Screen Identifies the Anti-Helminthic Niclosamide as an Inhibitor of Lysosome Anterograde Trafficking and Prostate Cancer Cell Invasion.

    Directory of Open Access Journals (Sweden)

    Magdalena L Circu

    Full Text Available Lysosome trafficking plays a significant role in tumor invasion, a key event for the development of metastasis. Previous studies from our laboratory have demonstrated that the anterograde (outward movement of lysosomes to the cell surface in response to certain tumor microenvironment stimulus, such as hepatocyte growth factor (HGF or acidic extracellular pH (pHe, increases cathepsin B secretion and tumor cell invasion. Anterograde lysosome trafficking depends on sodium-proton exchanger activity and can be reversed by blocking these ion pumps with Troglitazone or EIPA. Since these drugs cannot be advanced into the clinic due to toxicity, we have designed a high-content assay to discover drugs that block peripheral lysosome trafficking with the goal of identifying novel drugs that inhibit tumor cell invasion. An automated high-content imaging system (Cellomics was used to measure the position of lysosomes relative to the nucleus. Among a total of 2210 repurposed and natural product drugs screened, 18 "hits" were identified. One of the compounds identified as an anterograde lysosome trafficking inhibitor was niclosamide, a marketed human anti-helminthic drug. Further studies revealed that niclosamide blocked acidic pHe, HGF, and epidermal growth factor (EGF-induced anterograde lysosome redistribution, protease secretion, motility, and invasion of DU145 castrate resistant prostate cancer cells at clinically relevant concentrations. In an effort to identify the mechanism by which niclosamide prevented anterograde lysosome movement, we found that this drug exhibited no significant effect on the level of ATP, microtubules or actin filaments, and had minimal effect on the PI3K and MAPK pathways. Niclosamide collapsed intralysosomal pH without disruption of the lysosome membrane, while bafilomycin, an agent that impairs lysosome acidification, was also found to induce JLA in our model. Taken together, these data suggest that niclosamide promotes

  15. White-matter astrocytes, axonal energy metabolism, and axonal degeneration in multiple sclerosis

    Science.gov (United States)

    Cambron, Melissa; D'Haeseleer, Miguel; Laureys, Guy; Clinckers, Ralph; Debruyne, Jan; De Keyser, Jacques

    2012-01-01

    In patients with multiple sclerosis (MS), a diffuse axonal degeneration occurring throughout the white matter of the central nervous system causes progressive neurologic disability. The underlying mechanism is unclear. This review describes a number of pathways by which dysfunctional astrocytes in MS might lead to axonal degeneration. White-matter astrocytes in MS show a reduced metabolism of adenosine triphosphate-generating phosphocreatine, which may impair the astrocytic sodium potassium pump and lead to a reduced sodium-dependent glutamate uptake. Astrocytes in MS white matter appear to be deficient in β2 adrenergic receptors, which are involved in stimulating glycogenolysis and suppressing inducible nitric oxide synthase (NOS2). Glutamate toxicity, reduced astrocytic glycogenolysis leading to reduced lactate and glutamine production, and enhanced nitric oxide (NO) levels may all impair axonal mitochondrial metabolism, leading to axonal degeneration. In addition, glutamate-mediated oligodendrocyte damage and impaired myelination caused by a decreased production of N-acetylaspartate by axonal mitochondria might also contribute to axonal loss. White-matter astrocytes may be considered as a potential target for neuroprotective MS therapies. PMID:22214904

  16. Mislocalization of neuronal mitochondria reveals regulation of Wallerian degeneration and NMNAT/WLDS-mediated axon protection independent of axonal mitochondria

    OpenAIRE

    Kitay, Brandon M.; McCormack, Ryan; Wang, Yunfang; Tsoulfas, Pantelis; Zhai, R. Grace

    2013-01-01

    Axon degeneration is a common and often early feature of neurodegeneration that correlates with the clinical manifestations and progression of neurological disease. Nicotinamide mononucleotide adenylytransferase (NMNAT) is a neuroprotective factor that delays axon degeneration following injury and in models of neurodegenerative diseases suggesting a converging molecular pathway of axon self-destruction. The underlying mechanisms have been under intense investigation and recent reports suggest...

  17. AxonQuant: A Microfluidic Chamber Culture-Coupled Algorithm That Allows High-Throughput Quantification of Axonal Damage

    Directory of Open Access Journals (Sweden)

    Yang Li

    2014-02-01

    Full Text Available Published methods for imaging and quantitatively analyzing morphological changes in neuronal axons have serious limitations because of their small sample sizes, and their time-consuming and nonobjective nature. Here we present an improved microfluidic chamber design suitable for fast and high-throughput imaging of neuronal axons. We developed the AxonQuant algorithm, which is suitable for automatic processing of axonal imaging data. This microfluidic chamber-coupled algorithm allows calculation of an ‘axonal continuity index' that quantitatively measures axonal health status in a manner independent of neuronal or axonal density. This method allows quantitative analysis of axonal morphology in an automatic and nonbiased manner. Our method will facilitate large-scale high-throughput screening for genes or therapeutic compounds for neurodegenerative diseases involving axonal damage. When combined with imaging technologies utilizing different gene markers, this method will provide new insights into the mechanistic basis for axon degeneration. Our microfluidic chamber culture-coupled AxonQuant algorithm will be widely useful for studying axonal biology and neurodegenerative disorders. © 2014 S. Karger AG, Basel

  18. Quantitative analysis of microtubule transport in growing nerve processes

    DEFF Research Database (Denmark)

    Ma*, Ytao; Shakiryanova*, Dinara; Vardya, Irina;

    2004-01-01

    translocation of MT plus ends in the axonal shaft by expressing GFP-EB1 in Xenopus embryo neurons in culture. Formal quantitative analysis of MT assembly/disassembly indicated that none of the MTs in the axonal shaft were rapidly transported. Our results suggest that transport of axonal MTs is not required for...... delivery of newly synthesized tubulin to the growing nerve processes. Udgivelsesdato: 2004...

  19. Gamma-diketone axonopathy: analyses of cytoskeletal motors and highways in CNS myelinated axons.

    Science.gov (United States)

    Zhang, Lihai; Gavin, Terrence; DeCaprio, Anthony P; LoPachin, Richard M

    2010-09-01

    2,5-Hexanedione (HD) intoxication is associated with axon atrophy that might be responsible for the characteristic gait abnormalities, hindlimb skeletal muscle weakness and other neurological deficits that accompany neurotoxicity. Although previous mechanistic research focused on neurofilament triplet proteins (NFL, NFM, NFH), other cytoskeletal targets are possible. Therefore, to identify potential non-NF protein targets, we characterized the effects of HD on protein-protein interactions in cosedimentation assays using microtubules and NFs prepared from spinal cord of rats intoxicated at different daily dose rates (175 and 400 mg/kg/day). Results indicate that HD did not alter the presence of alpha- or beta-tubulins in these preparations, nor were changes noted in the distribution of either anterograde (KIF1A, KIF3, KIF5) or retrograde (dynein) molecular motors. The cosedimentation of dynactin, a dynein-associated protein, also was not affected. Immunoblot analysis of microtubule-associated proteins (MAPs) in microtubule preparations revealed substantial reductions (45-80%) in MAP1A, MAP1B heavy chain, MAP2, and tau regardless of HD dose rate. MAP1B light chain content was not altered. Finally, HD intoxication did not influence native NF protein content in either preparation. As per previous research, microtubule and NF preparations were enriched in high-molecular weight NF species. However, these NF derivatives were common to both HD and control samples, suggesting a lack of pathognomonic relevance. These data indicate that, although motor proteins were not affected, HD selectively impaired MAP-microtubule binding, presumably through adduction of lysine residues that mediate such interactions. Given their critical role in cytoskeletal physiology, MAPs could represent a relevant target for the induction of gamma-diketone axonopathy. PMID:20554699

  20. γ-Diketone Axonopathy: Analyses of Cytoskeletal Motors and Highways in CNS Myelinated Axons

    Science.gov (United States)

    Zhang, Lihai; Gavin, Terrence; DeCaprio, Anthony P.; LoPachin, Richard M.

    2010-01-01

    2,5-Hexanedione (HD) intoxication is associated with axon atrophy that might be responsible for the characteristic gait abnormalities, hindlimb skeletal muscle weakness and other neurological deficits that accompany neurotoxicity. Although previous mechanistic research focused on neurofilament triplet proteins (NFL, NFM, NFH), other cytoskeletal targets are possible. Therefore, to identify potential non-NF protein targets, we characterized the effects of HD on protein-protein interactions in cosedimentation assays using microtubules and NFs prepared from spinal cord of rats intoxicated at different daily dose rates (175 and 400 mg/kg/day). Results indicate that HD did not alter the presence of α- or β-tubulins in these preparations, nor were changes noted in the distribution of either anterograde (KIF1A, KIF3, KIF5) or retrograde (dynein) molecular motors. The cosedimentation of dynactin, a dynein-associated protein, also was not affected. Immunoblot analysis of microtubule-associated proteins (MAPs) in microtubule preparations revealed substantial reductions (45–80%) in MAP1A, MAP1B heavy chain, MAP2, and tau regardless of HD dose rate. MAP1B light chain content was not altered. Finally, HD intoxication did not influence native NF protein content in either preparation. As per previous research, microtubule and NF preparations were enriched in high–molecular weight NF species. However, these NF derivatives were common to both HD and control samples, suggesting a lack of pathognomonic relevance. These data indicate that, although motor proteins were not affected, HD selectively impaired MAP-microtubule binding, presumably through adduction of lysine residues that mediate such interactions. Given their critical role in cytoskeletal physiology, MAPs could represent a relevant target for the induction of γ-diketone axonopathy. PMID:20554699

  1. Anterograde Activin signaling regulates postsynaptic membrane potential and GluRIIA/B abundance at the Drosophila neuromuscular junction.

    Directory of Open Access Journals (Sweden)

    Myung-Jun Kim

    Full Text Available Members of the TGF-β superfamily play numerous roles in nervous system development and function. In Drosophila, retrograde BMP signaling at the neuromuscular junction (NMJ is required presynaptically for proper synapse growth and neurotransmitter release. In this study, we analyzed whether the Activin branch of the TGF-β superfamily also contributes to NMJ development and function. We find that elimination of the Activin/TGF-β type I receptor babo, or its downstream signal transducer smox, does not affect presynaptic NMJ growth or evoked excitatory junctional potentials (EJPs, but instead results in a number of postsynaptic defects including depolarized membrane potential, small size and frequency of miniature excitatory junction potentials (mEJPs, and decreased synaptic densities of the glutamate receptors GluRIIA and B. The majority of the defective smox synaptic phenotypes were rescued by muscle-specific expression of a smox transgene. Furthermore, a mutation in actβ, an Activin-like ligand that is strongly expressed in motor neurons, phenocopies babo and smox loss-of-function alleles. Our results demonstrate that anterograde Activin/TGF-β signaling at the Drosophila NMJ is crucial for achieving normal abundance and localization of several important postsynaptic signaling molecules and for regulating postsynaptic membrane physiology. Together with the well-established presynaptic role of the retrograde BMP signaling, our findings indicate that the two branches of the TGF-β superfamily are differentially deployed on each side of the Drosophila NMJ synapse to regulate distinct aspects of its development and function.

  2. Brainstem projections of neurons located in various subdivisions of the dorsolateral hypothalamic area – an anterograde tract-tracing study

    Directory of Open Access Journals (Sweden)

    Rege Sugárka Papp

    2014-05-01

    Full Text Available The projections from the dorsolateral hypothalamic area (DLH to the lower brainstem have been investigated by using biotinylated dextran amine (BDA, an anterograde tracer in rats. The DLH can be divided into 3 areas (dorsomedial hypothalamus, perifornical area, lateral hypothalamic area, and further subdivided into 8 subdivisions. After unilateral stereotaxic injections of BDA into individual DLH subdivisions, the correct sites of injections were controlled histologically, and the distribution patterns of BDA-positive fibers were mapped on serial sections between the hypothalamus and spinal cord in 22 rats. BDA-labeled fibers were observable over 100 different brainstem areas, nuclei or subdivisions. Injections into the 8 DLH subdivisions established distinct topographical patterns. In general, the density of labeled fibers was low in the lower brainstem. High density of fibers was seen only 4 of the 116 areas: in the lateral and ventrolateral parts of the periaqueductal gray, the Barrington’s and the pedunculopontine tegmental nuclei. All of the biogenic amine cell groups in the lower brainstem (9 noradrenaline, 3 adrenaline and 9 serotonin cell groups received labeled fibers, some of them from all, or at least 7 DLH subdivisions, mainly from perifornical and ventral lateral hypothalamic neurons. Some of the tegmental nuclei and nuclei of the reticular formation were widely innervated, although the density of the BDA-labeled fibers was generally low. No definitive descending BDA-positive pathway, but long-run solitaire BDA-labeled fibers were seen in the lower brainstem. These descending fibers joined some of the large tracts or fasciculi in the brainstem. The distribution pattern of BDA-positive fibers of DLH origin throughout the lower brainstem was comparable to patterns of previously published orexin- or melanin-concentrating hormone-immunoreactive fibers with somewhat differences.

  3. Axon Membrane Skeleton Structure is Optimized for Coordinated Sodium Propagation

    CERN Document Server

    Zhang, Yihao; Li, He; Tzingounis, Anastasios V; Lykotrafitis, George

    2016-01-01

    Axons transmit action potentials with high fidelity and minimal jitter. This unique capability is likely the result of the spatiotemporal arrangement of sodium channels along the axon. Super-resolution microscopy recently revealed that the axon membrane skeleton is structured as a series of actin rings connected by spectrin filaments that are held under entropic tension. Sodium channels also exhibit a periodic distribution pattern, as they bind to ankyrin G, which associates with spectrin. Here, we elucidate the relationship between the axon membrane skeleton structure and the function of the axon. By combining cytoskeletal dynamics and continuum diffusion modeling, we show that spectrin filaments under tension minimize the thermal fluctuations of sodium channels and prevent overlap of neighboring channel trajectories. Importantly, this axon skeletal arrangement allows for a highly reproducible band-like activation of sodium channels leading to coordinated sodium propagation along the axon.

  4. Axon position within the corpus callosum determines contralateral cortical projection.

    Science.gov (United States)

    Zhou, Jing; Wen, Yunqing; She, Liang; Sui, Ya-Nan; Liu, Lu; Richards, Linda J; Poo, Mu-Ming

    2013-07-16

    How developing axons in the corpus callosum (CC) achieve their homotopic projection to the contralateral cortex remains unclear. We found that axonal position within the CC plays a critical role in this projection. Labeling of nearby callosal axons in mice showed that callosal axons were segregated in an orderly fashion, with those from more medial cerebral cortex located more dorsally and subsequently projecting to more medial contralateral cortical regions. The normal axonal order within the CC was grossly disturbed when semaphorin3A/neuropilin-1 signaling was disrupted. However, the order in which axons were positioned within the CC still determined their contralateral projection, causing a severe disruption of the homotopic contralateral projection that persisted at postnatal day 30, when the normal developmental refinement of contralateral projections is completed in wild-type (WT) mice. Thus, the orderly positioning of axons within the CC is a primary determinant of how homotopic interhemispheric projections form in the contralateral cortex. PMID:23812756

  5. Motor axon synapses on renshaw cells contain higher levels of aspartate than glutamate.

    Directory of Open Access Journals (Sweden)

    Dannette S Richards

    Full Text Available Motoneuron synapses on spinal cord interneurons known as Renshaw cells activate nicotinic, AMPA and NMDA receptors consistent with co-release of acetylcholine and excitatory amino acids (EAA. However, whether these synapses express vesicular glutamate transporters (VGLUTs capable of accumulating glutamate into synaptic vesicles is controversial. An alternative possibility is that these synapses release other EAAs, like aspartate, not dependent on VGLUTs. To clarify the exact EAA concentrated at motor axon synapses we performed a quantitative postembedding colloidal gold immunoelectron analysis for aspartate and glutamate on motor axon synapses (identified by immunoreactivity to the vesicular acetylcholine transporter; VAChT contacting calbindin-immunoreactive (-IR Renshaw cell dendrites. The results show that 71% to 80% of motor axon synaptic boutons on Renshaw cells contained aspartate immunolabeling two standard deviations above average neuropil labeling. Moreover, VAChT-IR synapses on Renshaw cells contained, on average, aspartate immunolabeling at 2.5 to 2.8 times above the average neuropil level. In contrast, glutamate enrichment was lower; 21% to 44% of VAChT-IR synapses showed glutamate-IR two standard deviations above average neuropil labeling and average glutamate immunogold density was 1.7 to 2.0 times the neuropil level. The results were not influenced by antibody affinities because glutamate antibodies detected glutamate-enriched brain homogenates more efficiently than aspartate antibodies detecting aspartate-enriched brain homogenates. Furthermore, synaptic boutons with ultrastructural features of Type I excitatory synapses were always labeled by glutamate antibodies at higher density than motor axon synapses. We conclude that motor axon synapses co-express aspartate and glutamate, but aspartate is concentrated at higher levels than glutamate.

  6. Transport

    International Nuclear Information System (INIS)

    Transport is one of the major causes of environmental damage in Austria. Energy consumption, pollutants emissions, noise emissions, use of surfaces, sealing of surfaces, dissection of ecosystems and impact on landscape are the most significant environmental impacts caused by it. An overview of the transport development of passengers and freight in Austria is presented. Especially the energy consumption growth, carbon dioxide and nitrogen oxide emissions by type of transport, and the emissions development (HC, particle and carbon monoxide) of goods and passengers transport are analyzed covering the years 1980 - 1999. The health cost resulting from transport-related air pollution in Austria is given and measures to be taken for an effective control of the transport sector are mentioned. Figs. 8, Table 1. (nevyjel)

  7. The C-terminal domains of NF-H and NF-M subunits maintain axonal neurofilament content by blocking turnover of the stationary neurofilament network.

    Directory of Open Access Journals (Sweden)

    Mala V Rao

    Full Text Available Newly synthesized neurofilaments or protofilaments are incorporated into a highly stable stationary cytoskeleton network as they are transported along axons. Although the heavily phosphorylated carboxyl-terminal tail domains of the heavy and medium neurofilament (NF subunits have been proposed to contribute to this process and particularly to stability of this structure, their function is still obscure. Here we show in NF-H/M tail deletion [NF-(H/M(tailΔ] mice that the deletion of both of these domains selectively lowers NF levels 3-6 fold along optic axons without altering either rates of subunit synthesis or the rate of slow axonal transport of NF. Pulse labeling studies carried out over 90 days revealed a significantly faster rate of disappearance of NF from the stationary NF network of optic axons in NF-(H/M(tailΔ mice. Faster NF disappearance was accompanied by elevated levels of NF-L proteolytic fragments in NF-(H/M(tailΔ axons. We conclude that NF-H and NF-M C-terminal domains do not normally regulate NF transport rates as previously proposed, but instead increase the proteolytic resistance of NF, thereby stabilizing the stationary neurofilament cytoskeleton along axons.

  8. Focal axonal swellings and associated ultrastructural changes attenuate conduction velocity in central nervous system axons: a computer modeling study.

    Science.gov (United States)

    Kolaric, Katarina V; Thomson, Gemma; Edgar, Julia M; Brown, Angus M

    2013-08-01

    The constancy of action potential conduction in the central nervous system (CNS) relies on uniform axon diameter coupled with fidelity of the overlying myelin providing high-resistance, low capacitance insulation. Whereas the effects of demyelination on conduction have been extensively studied/modeled, equivalent studies on the repercussions for conduction of axon swelling, a common early pathological feature of (potentially reversible) axonal injury, are lacking. The recent description of experimentally acquired morphological and electrical properties of small CNS axons and oligodendrocytes prompted us to incorporate these data into a computer model, with the aim of simulating the effects of focal axon swelling on action potential conduction. A single swelling on an otherwise intact axon, as occurs in optic nerve axons of Cnp1 null mice caused a small decrease in conduction velocity. The presence of single swellings on multiple contiguous internodal regions (INR), as likely occurs in advanced disease, caused qualitatively similar results, except the dimensions of the swellings required to produce equivalent attenuation of conduction were significantly decreased. Our simulations of the consequences of metabolic insult to axons, namely, the appearance of multiple swollen regions, accompanied by perturbation of overlying myelin and increased axolemmal permeability, contained within a single INR, revealed that conduction block occurred when the dimensions of the simulated swellings were within the limits of those measured experimentally, suggesting that multiple swellings on a single axon could contribute to axonal dysfunction, and that increased axolemmal permeability is the decisive factor that promotes conduction block. PMID:24303138

  9. Early ultrastructural defects of axons and axon-glia junctions in mice lacking expression of Cnp1.

    Science.gov (United States)

    Edgar, Julia M; McLaughlin, Mark; Werner, Hauke B; McCulloch, Mailis C; Barrie, Jennifer A; Brown, Angus; Faichney, Andrew Blyth; Snaidero, Nicolas; Nave, Klaus-Armin; Griffiths, Ian R

    2009-12-01

    Most axons in the central nervous system (CNS) are surrounded by a multilayered myelin sheath that promotes fast, saltatory conduction of electrical impulses. By insulating the axon, myelin also shields the axoplasm from the extracellular milieu. In the CNS, oligodendrocytes provide support for the long-term maintenance of myelinated axons, independent of the myelin sheath. Here, we use electron microscopy and morphometric analyses to examine the evolution of axonal and oligodendroglial changes in mice deficient in 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP) and in mice deficient in both CNP and proteolipid protein (PLP/DM20). We show that CNP is necessary for the formation of a normal inner tongue process of oligodendrocytes that myelinate small diameter axons. We also show that axonal degeneration in Cnp1 null mice is present very early in postnatal life. Importantly, compact myelin formed by transplanted Cnp1 null oligodendrocytes induces the same degenerative changes in shiverer axons that normally are dysmyelinated but structurally intact. Mice deficient in both CNP and PLP develop a more severe axonal phenotype than either single mutant, indicating that the two oligodendroglial proteins serve distinct functions in supporting the myelinated axon. These observations support a model in which the trophic functions of oligodendrocytes serve to offset the physical shielding of axons by myelin membranes. PMID:19459211

  10. Dynamics of axon fasciculation in the presence of neuronal turnover

    CERN Document Server

    Chaudhuri, Debasish; Mohanty, P K; Zapotocky, Martin

    2008-01-01

    We formulate and characterize a model aiming to describe the formation of fascicles of axons mediated by contact axon-axon interactions. The growing axons are represented as interacting directed random walks in two spatial dimensions. To mimic axonal turnover in the mammalian olfactory system, the random walkers are injected and removed at specified rates. In the dynamical steady state, the position-dependent distribution of fascicle sizes obeys a scaling law. We identify several distinct time scales that emerge from the dynamics, are sensitive functions of the microscopic parameters of the model, and can exceed the average axonal lifetime by orders of magnitude. We discuss our findings in terms of an analytically tractable, effective model of fascicle dynamics.

  11. Dysregulation of the Axonal Trafficking of Nuclear-encoded Mitochondrial mRNA alters Neuronal Mitochondrial Activity and Mouse Behavior

    OpenAIRE

    Kar, Amar N.; Sun, Ching-Yu; Reichard, Kathryn; Gervasi, Noreen M.; Pickel, James; Nakazawa, Kazu; Gioio, Anthony E.; Kaplan, Barry B.

    2013-01-01

    Local translation of nuclear-encoded mitochondrial mRNAs is essential for mitochondrial activity, yet there is little insight into the role that axonal trafficking of these transcripts play in neuronal function and behavior. Previously, we identified a 38 nucleotide stem-loop structure (zipcode) in the 3′ untranslated region of the Cytochrome C oxidase IV (COXIV) mRNA that directs the transport of a reporter mRNA to the axon of superior cervical ganglion neurons (SCG). Over-expression of a ch...

  12. Axonal Protein Synthesis and the Regulation of Local Mitochondrial Function

    OpenAIRE

    2009-01-01

    Axons and presynaptic nerve terminals of both invertebrate and mammalian SCG neurons contain a heterogeneous population of nuclear-encoded mitochondrial mRNAs and a local cytosolic protein synthetic system. Nearly one quarter of the total protein synthesized in these structural/functional domains of the neuron is destined for mitochondria. Acute inhibition of axonal protein synthesis markedly reduces the functional activity of mitochondria. The blockade of axonal protein into mitochondria had...

  13. Axonal protein synthesis and the regulation of local mitochondrial function

    OpenAIRE

    Kaplan, B.B.; Gioio, A.E.; Hillefors, M.; Aschrafi, A.

    2009-01-01

    Axons and presynaptic nerve terminals of both invertebrate and mammalian SCG neurons contain a heterogeneous population of nuclear-encoded mitochondrial mRNAs and a local cytosolic protein synthetic system. Nearly one quarter of the total protein synthesized in these structural/functional domains of the neuron is destined for mitochondria. Acute inhibition of axonal protein synthesis markedly reduces the functional activity of mitochondria. The blockade of axonal protein into mitochondria had...

  14. Action potentials reliably invade axonal arbors of rat neocortical neurons

    OpenAIRE

    Cox, Charles L.; Denk, Winfried; Tank, David W.; Svoboda, Karel

    2000-01-01

    Neocortical pyramidal neurons have extensive axonal arborizations that make thousands of synapses. Action potentials can invade these arbors and cause calcium influx that is required for neurotransmitter release and excitation of postsynaptic targets. Thus, the regulation of action potential invasion in axonal branches might shape the spread of excitation in cortical neural networks. To measure the reliability and extent of action potential invasion into axonal arbors, we have used two-photon...

  15. Axon diameter mapping in crossing fibers with diffusion MRI

    DEFF Research Database (Denmark)

    Zhang, Hui; Dyrby, Tim B; Alexander, Daniel C

    2011-01-01

    tissue than measures derived from diffusion tensor imaging. Most existing techniques for axon diameter mapping assume a single axon orientation in the tissue model, which limits their application to only the most coherently oriented brain white matter, such as the corpus callosum, where the single...... technique by establishing reasonable axon diameter indices in the crossing region at the interface of the cingulum and the corpus callosum....

  16. Axon target matching in the developing visual system

    OpenAIRE

    Osterhout, Jessica A.

    2015-01-01

    The central nervous system (CNS) is made up of trillions of connections between specific sets of highly specialized neurons. How each individual neuron finds and connects to the correct synaptic partner remains an important and unresolved issue in neuroscience. Using the mouse visual system as a model I probed the cellular and molecular mechanisms that govern one of the key steps leading to CNS development: axon target matching. Axon target matching is the process by which axons to find and i...

  17. Axon Regeneration in the Peripheral and Central Nervous Systems

    OpenAIRE

    Huebner, Eric A.; Strittmatter, Stephen M

    2009-01-01

    Axon regeneration in the mature mammalian central nervous system (CNS) is extremely limited after injury. Consequently, functional deficits persist after spinal cord injury (SCI), traumatic brain injury, stroke, and related conditions that involve axonal disconnection. This situation differs from that in the mammalian peripheral nervous system (PNS), where long- distance axon regeneration and substantial functional recovery can occur in the adult. Both extracellular molecules and the intrinsi...

  18. Myelin sheath survival after guanethidine-induced axonal degeneration

    OpenAIRE

    1992-01-01

    Membrane-membrane interactions between axons and Schwann cells are required for initial myelin formation in the peripheral nervous system. However, recent studies of double myelination in sympathetic nerve have indicated that myelin sheaths continue to exist after complete loss of axonal contact (Kidd, G. J., and J. W. Heath. 1988. J. Neurocytol. 17:245-261). This suggests that myelin maintenance may be regulated either by diffusible axonal factors or by nonaxonal mechanisms. To test these hy...

  19. Axonal autophagy during regeneration of the rat sciatic nerve

    Institute of Scientific and Technical Information of China (English)

    Kangrong Lu; Zhongxian Piao; Zhenxi Liu; Weiwang Gu; Wanshan Wang; Nngjie Piao

    2008-01-01

    BACKGROUND: The removal of degenerated axonal debris during Wallerian degeneration is very important for nerve regeneration. However, the mechanism by which debris is removed is not been completely understood. Considerable controversy remains as to the clearance pathway and cells that are involved. OBJECTIVE: To investigate axonal autophagy during removal of degenerated axonal debris by transecting the sciatic nerve in a rat Wallerian degeneration model.DESIGN, TIME AND SETTING: Experimental neuropathological analysis. The experiment was conducted at the Laboratory Animal Service Center of the Southern Medical University between January and June 2005. MATERIALS: Fifty-four adult, Wistar rats of either sex, weighing 180-250 g, were obtained from the Laboratory Animal Service Center of the Southern Medical University. Animals were randomly divided into nine groups of six rats. METHODS: Wallerian degeneration was induced by transecting the rat sciatic nerve, and tissue samples from the distal stump were obtained 0.2, 0.4, 1, 2, 3, 4, 7, 10, and 15 days post-transection. Ultrathin sections were prepared for electron microscopy to study ultrastructure and enzyme cytochemistry staining. MAIN OUTCOME MEASURES: Ultrastructure (axon body, autophagic body, and cystoskeleton) of axons and myelin sheaths observed with electron microscopy; acidic phosphatase activity detected by Gomori staining using electron microscopy. RESULTS: The major changes of degenerating axons after transection were axoplasm swelling and separation of axons from their myelin sheath between five hours and two days post-transection. At four days post-transection, the axoplasm condensed and axons were completely separated from the myelin sheath, forming dissociative axon bodies. Vacuoles of different sizes formed in axons during the early phase after lesion. Larger dissociative axon bodies were formed when the axons were completely separated from the myelin sheath during a late phase. The axolemma

  20. Focal axonal swellings and associated ultrastructural changes attenuate conduction velocity in central nervous system axons: a computer modeling study

    OpenAIRE

    Kolaric, Katarina V; Thomson, Gemma; Edgar, Julia M; Brown, Angus M.

    2013-01-01

    The constancy of action potential conduction in the central nervous system (CNS) relies on uniform axon diameter coupled with fidelity of the overlying myelin providing high-resistance, low capacitance insulation. Whereas the effects of demyelination on conduction have been extensively studied/modeled, equivalent studies on the repercussions for conduction of axon swelling, a common early pathological feature of (potentially reversible) axonal injury, are lacking. The recent description of ex...

  1. Patterns of growth, axonal extension and axonal arborization of neuronal lineages in the developing Drosophila brain.

    Science.gov (United States)

    Larsen, Camilla; Shy, Diana; Spindler, Shana R; Fung, Siaumin; Pereanu, Wayne; Younossi-Hartenstein, Amelia; Hartenstein, Volker

    2009-11-15

    The Drosophila central brain is composed of approximately 100 paired lineages, with most lineages comprising 100-150 neurons. Most lineages have a number of important characteristics in common. Typically, neurons of a lineage stay together as a coherent cluster and project their axons into a coherent bundle visible from late embryo to adult. Neurons born during the embryonic period form the primary axon tracts (PATs) that follow stereotyped pathways in the neuropile. Apoptotic cell death removes an average of 30-40% of primary neurons around the time of hatching. Secondary neurons generated during the larval period form secondary axon tracts (SATs) that typically fasciculate with their corresponding primary axon tract. SATs develop into the long fascicles that interconnect the different compartments of the adult brain. Structurally, we distinguish between three types of lineages: PD lineages, characterized by distinct, spatially separate proximal and distal arborizations; C lineages with arborizations distributed continuously along the entire length of their tract; D lineages that lack proximal arborizations. Arborizations of many lineages, in particular those of the PD type, are restricted to distinct neuropile compartments. We propose that compartments are "scaffolded" by individual lineages, or small groups thereof. Thereby, the relatively small number of primary neurons of each primary lineage set up the compartment map in the late embryo. Compartments grow during the larval period simply by an increase in arbor volume of primary neurons. Arbors of secondary neurons form within or adjacent to the larval compartments, resulting in smaller compartment subdivisions and additional, adult specific compartments. PMID:19538956

  2. Peripheral nerve: from the microscopic functional unit of the axon to the biomechanically loaded macroscopic structure.

    Science.gov (United States)

    Topp, Kimberly S; Boyd, Benjamin S

    2012-01-01

    Peripheral nerves are composed of motor and sensory axons, associated ensheathing Schwann cells, and organized layers of connective tissues that are in continuity with the tissues of the central nervous system. Nerve fiber anatomy facilitates conduction of electrical impulses to convey information over a distance, and the length of these polarized cells necessitates regulated axonal transport of organelles and structural proteins for normal cell function. Nerve connective tissues serve a protective function as the limb is subjected to the stresses of myriad limb positions and postures. Thus, the tissues are uniquely arranged to control the local nerve fiber environment and modulate physical stresses. In this brief review, we describe the microscopic anatomy and physiology of peripheral nerve and the biomechanical properties that enable nerve to withstand the physical stresses of everyday life. PMID:22133662

  3. New insights into mRNA trafficking in axons

    NARCIS (Netherlands)

    Gumy, Laura; Katrukha, Eugene; Kapitein, Lukas; Hoogenraad, Casper

    2014-01-01

    In recent years, it has been demonstrated that mRNAs localize to axons of young and mature central and peripheral nervous system neurons in culture and in vivo. Increasing evidence is supporting a fundamental role for the local translation of these mRNAs in neuronal function by regulating axon growt

  4. Axonal accumulation of synaptic markers in APP transgenic Drosophila depends on the NPTY motif and is paralleled by defects in synaptic plasticity

    DEFF Research Database (Denmark)

    Rusu, Patricia; Jansen, Anna; Soba, Peter;

    2007-01-01

    Alzheimer's disease (AD) is characterized by neurofibrillary tangles and extracellular plaques, which consist mainly of beta-amyloid derived from the beta-amyloid precursor protein (APP). An additional feature of AD is axonopathy, which might contribute to impairment of cognitive functions....... Specifically, axonal transport defects have been reported in AD animal models, including mice and flies that overexpress APP and tau. Here we demonstrate that the APP-induced traffic jam of vesicles in peripheral nerves of Drosophila melanogaster larvae depends on the four residues NPTY motif in the APP...... intracellular domain. Furthermore, heterologous expression of Fe65 and JIP1b, scaffolding proteins interacting with the NPTY motif, also perturb axonal transport. Together, these data indicate that JIP1b or Fe65 may be involved in the APP-induced axonal transport defect. Moreover, we have characterized...

  5. Restoration of Visual Function by Enhancing Conduction in Regenerated Axons.

    Science.gov (United States)

    Bei, Fengfeng; Lee, Henry Hing Cheong; Liu, Xuefeng; Gunner, Georgia; Jin, Hai; Ma, Long; Wang, Chen; Hou, Lijun; Hensch, Takao K; Frank, Eric; Sanes, Joshua R; Chen, Chinfei; Fagiolini, Michela; He, Zhigang

    2016-01-14

    Although a number of repair strategies have been shown to promote axon outgrowth following neuronal injury in the mammalian CNS, it remains unclear whether regenerated axons establish functional synapses and support behavior. Here, in both juvenile and adult mice, we show that either PTEN and SOCS3 co-deletion, or co-overexpression of osteopontin (OPN)/insulin-like growth factor 1 (IGF1)/ciliary neurotrophic factor (CNTF), induces regrowth of retinal axons and formation of functional synapses in the superior colliculus (SC) but not significant recovery of visual function. Further analyses suggest that regenerated axons fail to conduct action potentials from the eye to the SC due to lack of myelination. Consistent with this idea, administration of voltage-gated potassium channel blockers restores conduction and results in increased visual acuity. Thus, enhancing both regeneration and conduction effectively improves function after retinal axon injury. PMID:26771493

  6. Receptor Tyrosine Kinases: Molecular Switches Regulating CNS Axon Regeneration

    Directory of Open Access Journals (Sweden)

    Vasanthy Vigneswara

    2012-01-01

    Full Text Available The poor or lack of injured adult central nervous system (CNS axon regeneration results in devastating consequences and poor functional recovery. The interplay between the intrinsic and extrinsic factors contributes to robust inhibition of axon regeneration of injured CNS neurons. The insufficient or lack of trophic support for injured neurons is considered as one of the major obstacles contributing to their failure to survive and regrow their axons after injury. In the CNS, many of the signalling pathways associated with neuronal survival and axon regeneration are regulated by several classes of receptor tyrosine kinases (RTK that respond to a variety of ligands. This paper highlights and summarises the most relevant recent findings pertinent to different classes of the RTK family of molecules, with a particular focus on elucidating their role in CNS axon regeneration.

  7. SnoN facilitates axonal regeneration after spinal cord injury.

    Directory of Open Access Journals (Sweden)

    Jiun L Do

    Full Text Available Adult CNS neurons exhibit a reduced capacity for growth compared to developing neurons, due in part to downregulation of growth-associated genes as development is completed. We tested the hypothesis that SnoN, an embryonically regulated transcription factor that specifies growth of the axonal compartment, can enhance growth in injured adult neurons. In vitro, SnoN overexpression in dissociated adult DRG neuronal cultures significantly enhanced neurite outgrowth. Moreover, TGF-β1, a negative regulator of SnoN, inhibited neurite outgrowth, and SnoN over-expression overcame this inhibition. We then examined whether SnoN influenced axonal regeneration in vivo: indeed, expression of a mutant form of SnoN resistant to degradation significantly enhanced axonal regeneration following cervical spinal cord injury, despite peri-lesional upregulation of TGF-β1. Thus, a developmental mechanism that specifies extension of the axonal compartment also promotes axonal regeneration after adult CNS injury.

  8. Brain injury tolerance limit based on computation of axonal strain.

    Science.gov (United States)

    Sahoo, Debasis; Deck, Caroline; Willinger, Rémy

    2016-07-01

    Traumatic brain injury (TBI) is the leading cause of death and permanent impairment over the last decades. In both the severe and mild TBIs, diffuse axonal injury (DAI) is the most common pathology and leads to axonal degeneration. Computation of axonal strain by using finite element head model in numerical simulation can enlighten the DAI mechanism and help to establish advanced head injury criteria. The main objective of this study is to develop a brain injury criterion based on computation of axonal strain. To achieve the objective a state-of-the-art finite element head model with enhanced brain and skull material laws, was used for numerical computation of real world head trauma. The implementation of new medical imaging data such as, fractional anisotropy and axonal fiber orientation from Diffusion Tensor Imaging (DTI) of 12 healthy patients into the finite element brain model was performed to improve the brain constitutive material law with more efficient heterogeneous anisotropic visco hyper-elastic material law. The brain behavior has been validated in terms of brain deformation against Hardy et al. (2001), Hardy et al. (2007), and in terms of brain pressure against Nahum et al. (1977) and Trosseille et al. (1992) experiments. Verification of model stability has been conducted as well. Further, 109 well-documented TBI cases were simulated and axonal strain computed to derive brain injury tolerance curve. Based on an in-depth statistical analysis of different intra-cerebral parameters (brain axonal strain rate, axonal strain, first principal strain, Von Mises strain, first principal stress, Von Mises stress, CSDM (0.10), CSDM (0.15) and CSDM (0.25)), it was shown that axonal strain was the most appropriate candidate parameter to predict DAI. The proposed brain injury tolerance limit for a 50% risk of DAI has been established at 14.65% of axonal strain. This study provides a key step for a realistic novel injury metric for DAI. PMID:27038501

  9. Prolyl Isomerase Pin1 Regulates Axon Guidance by Stabilizing CRMP2A Selectively in Distal Axons

    Czech Academy of Sciences Publication Activity Database

    Balaštík, Martin; Zhou, X.Z.; Alberich-Jorda, Meritxell; Weissová, Romana; Žiak, Jakub; Pazyra-Murphy, M.F.; Cosker, K.E.; Machoňová, Olga; Kozmiková, Iryna; Chen, CH.; Pastorino, L.; Asara, J.M.; Cole, A.; Sutherland, C.; Segal, R. A.; Lu, K.P.

    2015-01-01

    Roč. 13, č. 4 (2015), s. 812-828. ISSN 2211-1247 R&D Projects: GA MŠk(CZ) LK11213; GA MŠk LK21307; GA ČR GA15-03796S; GA MŠk LO1419 Institutional support: RVO:68378050 Keywords : Pin1 * axon guidance * Semaphorin 3A Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 8.358, year: 2014

  10. Clinical features of diffuse axonal injury

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Objective: To analyze the mechanism of diffuse axonal injury (DAI) and study the relationship between DAI and brain concussion, brain contusion, and primary brain stem injury.Methods: The clinical data and iconographic characteristics of 56 patients with DAI were analyzed retrospectively.Results: Traffic accidents were the main cause of DAI. Among the 56 cases, 34 were injured for at least twice, and 71.43% of the patients were complicated with contusion.Conclusions: It is considered that DAI is a common pattern of primary brain injury, which is often underestimated. And DAI includes cerebral concussion and primary brain injury, and is often complicated by cerebral cortex contusion. Therefore, it is very simple and practical to divide primary brain injuries into local and diffuse injuries.

  11. Transhepatic anterograde biliary drainage using a self-expandable metallic stent: a therapeutic alternative after hepaticojejunostomy with Roux-en-Y reconstruction

    Directory of Open Access Journals (Sweden)

    Fernando Macías-García

    2013-06-01

    Full Text Available Endoscopic drainage is the procedure of choice in cases of obstructive jaundice. However, in patients with a surgical biliary reconstruction, this technique cannot be often satisfactorily used. In these cases, the best alternative has usually been the percutaneous biliary drainage. Since the introduction of endoscopic ultrasound-guided therapy, some new techniques have been proposed to solve these technical problems related to postsurgical disturbed anatomy. In this case report, we describe our successful experience in the performance of a transhepatic anterograde biliary drainage using a self-expandable metallic stent in the context of a patient who previously had undergone a hepaticojejunostomy with Roux-en-Y reconstruction because of a resected hilar cholangiocarcinoma.

  12. Astrocyte scar formation aids central nervous system axon regeneration.

    Science.gov (United States)

    Anderson, Mark A; Burda, Joshua E; Ren, Yilong; Ao, Yan; O'Shea, Timothy M; Kawaguchi, Riki; Coppola, Giovanni; Khakh, Baljit S; Deming, Timothy J; Sofroniew, Michael V

    2016-04-14

    Transected axons fail to regrow in the mature central nervous system. Astrocytic scars are widely regarded as causal in this failure. Here, using three genetically targeted loss-of-function manipulations in adult mice, we show that preventing astrocyte scar formation, attenuating scar-forming astrocytes, or ablating chronic astrocytic scars all failed to result in spontaneous regrowth of transected corticospinal, sensory or serotonergic axons through severe spinal cord injury (SCI) lesions. By contrast, sustained local delivery via hydrogel depots of required axon-specific growth factors not present in SCI lesions, plus growth-activating priming injuries, stimulated robust, laminin-dependent sensory axon regrowth past scar-forming astrocytes and inhibitory molecules in SCI lesions. Preventing astrocytic scar formation significantly reduced this stimulated axon regrowth. RNA sequencing revealed that astrocytes and non-astrocyte cells in SCI lesions express multiple axon-growth-supporting molecules. Our findings show that contrary to the prevailing dogma, astrocyte scar formation aids rather than prevents central nervous system axon regeneration. PMID:27027288

  13. Intra-axonal myosin and actin in nerve regeneration.

    Science.gov (United States)

    McQuarrie, Irvine G; Lund, Linda M

    2009-10-01

    A focused review of sciatic nerve regeneration in the rat model, based on research conducted by the authors, is presented. We examine structural proteins carried distally in the axon by energy-requiring motor enzymes, using protein chemistry and molecular biology techniques in combination with immunohistochemistry. Relevant findings from other laboratories are cited and discussed. The general conclusion is that relatively large amounts of actin and tubulin are required to construct a regenerating axon and that these materials mainly originate in the parent axon. The motor enzymes that carry these proteins forward as macromolecules include kinesin and dynein but probably also include myosin. PMID:19927086

  14. Axon guidance and neuronal migration research in China

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Proper migration of neuronal somas and axonal growth cones to designated locations in the developing brain is essential for the assembly of functional neuronal circuits.Rapid progress in research of axon guidance and neuronal migration has been made in the last twenty years.Chinese researchers began their exploration in this field ten years ago and have made significant contributions in clarifying the signal transduction of axon guidance and neuronal migration.Several unique experimental approaches,including the migration assay of single isolated neurons in response to locally delivered guidance cues,have been developed by Chinese neuroscientists to investigate the molecular machinery underlying these guidance events.

  15. Genetics Home Reference: autosomal recessive axonal neuropathy with neuromyotonia

    Science.gov (United States)

    ... neuromyotonia is a disorder that affects the peripheral nerves. Peripheral nerves connect the brain and spinal cord to muscles ... caused by damage to a particular part of peripheral nerves called axons , which are the extensions of nerve ...

  16. Internodal function in normal and regenerated mammalian axons

    DEFF Research Database (Denmark)

    Moldovan, M; Krarup, C

    2007-01-01

    AIM: Following Wallerian degeneration, peripheral myelinated axons have the ability to regenerate and, given a proper pathway, establish functional connections with targets. In spite of this capacity, the clinical outcome of nerve regeneration remains unsatisfactory. Early studies have found that...

  17. Syndecan Promotes Axon Regeneration by Stabilizing Growth Cone Migration

    Directory of Open Access Journals (Sweden)

    Tyson J. Edwards

    2014-07-01

    Full Text Available Growth cones facilitate the repair of nervous system damage by providing the driving force for axon regeneration. Using single-neuron laser axotomy and in vivo time-lapse imaging, we show that syndecan, a heparan sulfate (HS proteoglycan, is required for growth cone function during axon regeneration in C. elegans. In the absence of syndecan, regenerating growth cones form but are unstable and collapse, decreasing the effective growth rate and impeding regrowth to target cells. We provide evidence that syndecan has two distinct functions during axon regeneration: (1 a canonical function in axon guidance that requires expression outside the nervous system and depends on HS chains and (2 an intrinsic function in growth cone stabilization that is mediated by the syndecan core protein, independently of HS. Thus, syndecan is a regulator of a critical choke point in nervous system repair.

  18. Treadmill Training Promotes Axon Regeneration in Injured Peripheral Nerves

    OpenAIRE

    Sabatier, Manning J.; Redmon, Natalie; Schwartz, Gail; English, Arthur W.

    2008-01-01

    Physical activity after spinal cord injury promotes improvements in motor function, but its effects following peripheral nerve injury are less clear. Although axons in peripheral nerves are known to regenerate better than those in the CNS, methods of accelerating regeneration are needed due to the slow overall rate of growth. Therefore we studied the effect of two weeks of treadmill locomotion on the growth of regenerating axons in peripheral nerves following injury. The common fibular nerves...

  19. Fcγ receptor-mediated inflammation inhibits axon regeneration.

    Directory of Open Access Journals (Sweden)

    Gang Zhang

    Full Text Available Anti-glycan/ganglioside antibodies are the most common immune effectors found in patients with Guillain-Barré Syndrome, which is a peripheral autoimmune neuropathy. We previously reported that disease-relevant anti-glycan autoantibodies inhibited axon regeneration, which echo the clinical association of these antibodies and poor recovery in Guillain-Barré Syndrome. However, the specific molecular and cellular elements involved in this antibody-mediated inhibition of axon regeneration are not previously defined. This study examined the role of Fcγ receptors and macrophages in the antibody-mediated inhibition of axon regeneration. A well characterized antibody passive transfer sciatic nerve crush and transplant models were used to study the anti-ganglioside antibody-mediated inhibition of axon regeneration in wild type and various mutant and transgenic mice with altered expression of specific Fcγ receptors and macrophage/microglia populations. Outcome measures included behavior, electrophysiology, morphometry, immunocytochemistry, quantitative real-time PCR, and western blotting. We demonstrate that the presence of autoantibodies, directed against neuronal/axonal cell surface gangliosides, in the injured mammalian peripheral nerves switch the proregenerative inflammatory environment to growth inhibitory milieu by engaging specific activating Fcγ receptors on recruited monocyte-derived macrophages to cause severe inhibition of axon regeneration. Our data demonstrate that the antibody orchestrated Fcγ receptor-mediated switch in inflammation is one mechanism underlying inhibition of axon regeneration. These findings have clinical implications for nerve repair and recovery in antibody-mediated immune neuropathies. Our results add to the complexity of axon regeneration in injured peripheral and central nervous systems as adverse effects of B cells and autoantibodies on neural injury and repair are increasingly recognized.

  20. Modality-Specific Axonal Regeneration: Towards selective regenerative neural interfaces

    Directory of Open Access Journals (Sweden)

    Mario I Romero

    2011-10-01

    Full Text Available Regenerative peripheral nerve interfaces have been proposed as viable alternatives for the natural control of robotic prosthetic devices. However, sensory and motor axons at the neural interface are of mixed submodality types, which difficult the specific recording from motor axons and the eliciting of precise sensory modalities through selective stimulation. Here we evaluated the possibility of using type-specific neurotrophins to preferentially entice the regeneration of defined axonal populations from transected peripheral nerves into separate compartments. Segregation of mixed sensory fibers from dorsal root ganglion neurons was evaluated in vitro by compartmentalized diffusion delivery of nerve growth factor (NGF and neurotrophin-3 (NT-3, to preferentially entice the growth of TrkA+ nociceptive and TrkC+ proprioceptive subsets of sensory neurons, respectively. The average axon length in the NGF channel increased 2.5 fold compared to that in saline or NT-3, whereas the number of branches increased 3 fold in the NT-3 channels. These results were confirmed using a 3-D “Y”-shaped in vitro assay showing that the arm containing NGF was able to entice a 5-fold increase in axonal length of unbranched fibers. To address if such segregation can be enticed in vivo, a “Y”-shaped tubing was used to allow regeneration of the transected adult rat sciatic nerve into separate compartments filled with either NFG or NT-3. A significant increase in the number of CGRP+ pain fibers were attracted towards the sural nerve, while N-52+ large diameter axons were observed in the tibial and NT-3 compartments. This study demonstrates the guided enrichment of sensory axons in specific regenerative chambers, and supports the notion that neurotrophic factors can be used to segregate sensory and perhaps motor axons in separate peripheral interfaces.

  1. Axonal integrity predicts cortical reorganisation following cervical injury

    OpenAIRE

    Freund, P.; Wheeler-Kingshott, C.A.; Nagy, Z.; Gorgoraptis, N.; N. Weiskopf; Friston, K.; Thompson, A J; Hutton, C.

    2012-01-01

    Background Traumatic spinal cord injury (SCI) leads to disruption of axonal architecture and macroscopic tissue loss with impaired information flow between the brain and spinal cord—the presumed basis of ensuing clinical impairment. Objective The authors used a clinically viable, multimodal MRI protocol to quantify the axonal integrity of the cranial corticospinal tract (CST) and to establish how microstructural white matter changes in the CST are related to cross-sectional spinal cord area a...

  2. Axonal neuropathy associated with monoclonal gammopathy of undetermined significance

    OpenAIRE

    GORSON, K.; Ropper, A.

    1997-01-01

    OBJECTIVE—The neuropathy associated with monoclonal gammopathy of undetermined significance (MGUS) is typically a predominantly demyelinating process that may have additional features of axonal degeneration. Sixteen patients with MGUS and a pure or predominantly axonal neuropathy are reported and compared with 20 consecutive patients with demyelinating neuropathy and MGUS who were seen during the same period.
METHODS—Retrospective review of a consecutive series of patients w...

  3. Changes in prefrontal axons may disrupt the network in autism

    OpenAIRE

    Zikopoulos, Basilis; Barbas, Helen

    2010-01-01

    Neural communication is disrupted in autism by unknown mechanisms. Here we examined whether in autism there are changes in axons, which are the conduit for neural communication. We investigated single axons and their ultrastructure in the white matter of post-mortem human brain tissue below the anterior cingulate cortex (ACC), orbitofrontal (OFC), and lateral (LPFC) prefrontal cortices, which are associated with attention, social interactions, and emotions and have been consistently implicate...

  4. Axonal maintenance, glia, exosomes, and heat shock proteins

    OpenAIRE

    Michael Tytell; Lasek, Raymond J.; Harold Gainer

    2016-01-01

    Of all cellular specializations, the axon is especially distinctive because it is a narrow cylinder of specialized cytoplasm called axoplasm with a length that may be orders of magnitude greater than the diameter of the cell body from which it originates. Thus, the volume of axoplasm can be much greater than the cytoplasm in the cell body. This fact raises a logistical problem with regard to axonal maintenance. Many of the components of axoplasm, such as soluble proteins and cytoskeleton, are...

  5. THEORETICAL PRINCIPLES UNDERLYING OPTICAL STIMULATION OF MYELINATED AXONS EXPRESSING CHANNELRHODOPSIN-2

    OpenAIRE

    ARLOW, R. L.; FOUTZ, T. J.; MCINTYRE, C. C.

    2013-01-01

    Numerous clinical conditions can be treated by neuromodulation of the peripheral nervous system (PNS). Typical electrical PNS therapies activate large diameter axons at lower electrical stimulus thresholds than small diameter axons. However, recent animal experiments with peripheral optogenetic neural stimulation (PONS) of myelinated axons expressing channelrhodopsin-2 (ChR2) have shown that this technique activates small diameter axons at lower irradiances than large diameter axons. We hypot...

  6. Spinal irradiation does not inhibit distal axonal sprouting

    International Nuclear Information System (INIS)

    In an attempt to determine the relative importance of the nerve cell body and of the axon in initiating and controlling axonal regeneration, nerve cell bodies were irradiated and the ability of the distal axon to sprout was examined. Mice were subjected to either 25 or 50 Gray (Gy) of x-irradiation localized to the lumbar spinal cord. After times varying from 1 day to 6 months after irradiation, a sublethal dose of botulinum toxin (BoTx) was injected into the calf muscles of one leg. The soleus muscle was examined histologically after times varying from 1 week to 6 months after injection, and BoTx-induced ultraterminal axonal sprouting was assessed by the number of motor endplates showing sprouts, the length of the sprouts, and the long term endplate morphology. Apart from some irradiated subgroups having slightly shorter sprout lengths, no significant differences were found between irradiated and nonirradiated groups. The results suggest either that the processes in the nerve cell body responsible for initiating and supporting axonal growth are resistant to large doses of irradiation, or that growth regulatory mechanisms in the distal axon are under local control

  7. Dynamics of signal propagation and collision in axons

    Science.gov (United States)

    Follmann, Rosangela; Rosa, Epaminondas; Stein, Wolfgang

    2015-09-01

    Long-range communication in the nervous system is usually carried out with the propagation of action potentials along the axon of nerve cells. While typically thought of as being unidirectional, it is not uncommon for axonal propagation of action potentials to happen in both directions. This is the case because action potentials can be initiated at multiple "ectopic" positions along the axon. Two ectopic action potentials generated at distinct sites, and traveling toward each other, will collide. As neuronal information is encoded in the frequency of action potentials, action potential collision and annihilation may affect the way in which neuronal information is received, processed, and transmitted. We investigate action potential propagation and collision using an axonal multicompartment model based on the Hodgkin-Huxley equations. We characterize propagation speed, refractory period, excitability, and action potential collision for slow (type I) and fast (type II) axons. In addition, our studies include experimental measurements of action potential propagation in axons of two biological systems. Both computational and experimental results unequivocally indicate that colliding action potentials do not pass each other; they are reciprocally annihilated.

  8. Ultrastructural observation of effect of moderate hypothermia on axonal damage in an animal model of diffuse axonal injury

    Institute of Scientific and Technical Information of China (English)

    孙晓川; 唐文渊; 郑履平

    2002-01-01

    Objective: To investigate the effect of moderate hypothermia on responses of axonal cytoskeleton to axonal injury in the acute stage of injury. Methods: Of fifteen adult guinea pigs, twelve animals were subjected to stretch injury to the right optic nerves and divided into the normothermic group (n=6) in which the animal's core temperature was maintained at 36.0-37.5℃ and the hypothermia group (n=6) in which the core temperature was reduced to 32.0-32.5℃ after stretch injury. Remaining three animals sustained no injury to the right optic nerves and served as control group. Half of injured animals (n=3) of either normothermic group or hypothermic group were killed at either 2 hours or 4 hours after injury. The ultrastructural changes of axonal cytoskeleton of the right optic nerve fibers from the animals were examined under a transmission electron microscope and analyzed by quantitative analysis with a computer image analysis system. Results: At 2 hours after stretch injury, there was a significant reduction in the mean number of microtubules (P<0.001), and a significant increase in the mean intermicrotubule spacing (P<0.05 or P<0.01) in axons of all sizes in normothermic animals. The mean number of neurofilaments also decreased statistically (P<0.01) in large and medium subgroups of axons in the same experimental group at 2 hours. By 4 hours, the large subgroup of axons in normothermic animals still demonstrated a significant decline in the mean number of microtubules (P<0.01) and an increase in the mean intermicrotubule spacing (P<0.05), while the medium and small subgroups of axons displayed a significant increase in the mean number of neurofilaments (P<0.05) and reduction in the mean interneurofilament spacing (P<0.05). On the contrary, either the mean number of microtubules and the mean intermicrotubule spacing, or the mean number of neurofilaments and interneurofilament spacing in axons of all sizes in hypothermic stretch-injured animals was not

  9. Axonal synapses utilize multiple synaptic ribbons in the mammalian retina.

    Directory of Open Access Journals (Sweden)

    Hong-Lim Kim

    Full Text Available In the mammalian retina, bipolar cells and ganglion cells which stratify in sublamina a of the inner plexiform layer (IPL show OFF responses to light stimuli while those that stratify in sublamina b show ON responses. This functional relationship between anatomy and physiology is a key principle of retinal organization. However, there are at least three types of retinal neurons, including intrinsically photosensitive retinal ganglion cells (ipRGCs and dopaminergic amacrine cells, which violate this principle. These cell types have light-driven ON responses, but their dendrites mainly stratify in sublamina a of the IPL, the OFF sublayer. Recent anatomical studies suggested that certain ON cone bipolar cells make axonal or ectopic synapses as they descend through sublamina a, thus providing ON input to cells which stratify in the OFF sublayer. Using immunoelectron microscopy with 3-dimensional reconstruction, we have identified axonal synapses of ON cone bipolar cells in the rabbit retina. Ten calbindin ON cone bipolar axons made en passant ribbon synapses onto amacrine or ganglion dendrites in sublamina a of the IPL. Compared to the ribbon synapses made by bipolar terminals, these axonal ribbon synapses were characterized by a broad postsynaptic element that appeared as a monad and by the presence of multiple short synaptic ribbons. These findings confirm that certain ON cone bipolar cells can provide ON input to amacrine and ganglion cells whose dendrites stratify in the OFF sublayer via axonal synapses. The monadic synapse with multiple ribbons may be a diagnostic feature of the ON cone bipolar axonal synapse in sublamina a. The presence of multiple ribbons and a broad postsynaptic density suggest these structures may be very efficient synapses. We also identified axonal inputs to ipRGCs with the architecture described above.

  10. Myelinated sensory and alpha motor axon regeneration in peripheral nerve neuromas

    Science.gov (United States)

    Macias, M. Y.; Lehman, C. T.; Sanger, J. R.; Riley, D. A.

    1998-01-01

    Histochemical staining for carbonic anhydrase and cholinesterase (CE) activities was used to analyze sensory and motor axon regeneration, respectively, during neuroma formation in transected and tube-encapsulated peripheral nerves. Median-ulnar and sciatic nerves in the rodent model permitted testing whether a 4 cm greater distance of the motor neuron soma from axotomy site or intrinsic differences between motor and sensory neurons influenced regeneration and neuroma formation 10, 30, and 90 days later. Ventral root radiculotomy confirmed that CE-stained axons were 97% alpha motor axons. Distance significantly delayed axon regeneration. When distance was negligible, sensory axons grew out sooner than motor axons, but motor axons regenerated to a greater quantity. These results indicate regeneration differences between axon subtypes and suggest more extensive branching of motor axons within the neuroma. Thus, both distance from injury site to soma and inherent motor and sensory differences should be considered in peripheral nerve repair strategies.

  11. Regulation of Microtubule Dynamics in Axon Regeneration: Insights from C. elegans [version 1; referees: 3 approved

    Directory of Open Access Journals (Sweden)

    Ngang Heok Tang

    2016-04-01

    Full Text Available The capacity of an axon to regenerate is regulated by its external environment and by cell-intrinsic factors. Studies in a variety of organisms suggest that alterations in axonal microtubule (MT dynamics have potent effects on axon regeneration. We review recent findings on the regulation of MT dynamics during axon regeneration, focusing on the nematode Caenorhabditis elegans. In C. elegans the dual leucine zipper kinase (DLK promotes axon regeneration, whereas the exchange factor for Arf6 (EFA-6 inhibits axon regeneration. Both DLK and EFA-6 respond to injury and control axon regeneration in part via MT dynamics. How the DLK and EFA-6 pathways are related is a topic of active investigation, as is the mechanism by which EFA-6 responds to axonal injury. We evaluate potential candidates, such as the MT affinity-regulating kinase PAR-1/MARK, in regulation of EFA-6 and axonal MT dynamics in regeneration.

  12. Functional complexity of the axonal growth cone: a proteomic analysis.

    Directory of Open Access Journals (Sweden)

    Adriana Estrada-Bernal

    Full Text Available The growth cone, the tip of the emerging neurite, plays a crucial role in establishing the wiring of the developing nervous system. We performed an extensive proteomic analysis of axonal growth cones isolated from the brains of fetal Sprague-Dawley rats. Approximately 2000 proteins were identified at ≥ 99% confidence level. Using informatics, including functional annotation cluster and KEGG pathway analysis, we found great diversity of proteins involved in axonal pathfinding, cytoskeletal remodeling, vesicular traffic and carbohydrate metabolism, as expected. We also found a large and complex array of proteins involved in translation, protein folding, posttranslational processing, and proteasome/ubiquitination-dependent degradation. Immunofluorescence studies performed on hippocampal neurons in culture confirmed the presence in the axonal growth cone of proteins representative of these processes. These analyses also provide evidence for rough endoplasmic reticulum and reveal a reticular structure equipped with Golgi-like functions in the axonal growth cone. Furthermore, Western blot revealed the growth cone enrichment, relative to fetal brain homogenate, of some of the proteins involved in protein synthesis, folding and catabolism. Our study provides a resource for further research and amplifies the relatively recently developed concept that the axonal growth cone is equipped with proteins capable of performing a highly diverse range of functions.

  13. A novel technique using hydrophilic polymers to promote axonal fusion

    Institute of Scientific and Technical Information of China (English)

    Ravinder Bamba; D Colton Riley; Nathaniel D Kelm; Mark D Does; Richard D Dortch; Wesley P hTayer

    2016-01-01

    The management of traumatic peripheral nerve injury remains a considerable concern for clinicians. With minimal innovations in surgical technique and a limited number of specialists trained to treat peripheral nerve injury, outcomes of surgical intervention have been unpredictable. The inability to manipulate the pathophysiology of nerve injury (i.e., Wallerian degeneration) has left scientists and clinicians depending on the slow and lengthy process of axonal regeneration (~1 mm/day). When axons are severed, the endings undergo calcium-mediated plasmalemmal sealing, which limits the ability of the axon to be primarily re-paired. Polythethylene glycol (PEG) in combination with a bioengineered process overcomes the inability to fuse axons. The mechanism for PEG axonal fusion is not clearly understood, but multiple studies have shown that a providing a calcium-free environment is essential to the process known as PEG fusion. The proposed mechanism is PEG-induced lipid bilayer fusion by removing the hydration barrier surrounding the axolemma and reducing the activation energy required for membrane fusion to occur. This review highlights PEG fusion, its past and current studies, and future directions in PEG fusion.

  14. Highly effective photonic cue for repulsive axonal guidance.

    Directory of Open Access Journals (Sweden)

    Bryan J Black

    Full Text Available In vivo nerve repair requires not only the ability to regenerate damaged axons, but most importantly, the ability to guide developing or regenerating axons along paths that will result in functional connections. Furthermore, basic studies in neuroscience and neuro-electronic interface design require the ability to construct in vitro neural circuitry. Both these applications require the development of a noninvasive, highly effective tool for axonal growth-cone guidance. To date, a myriad of technologies have been introduced based on chemical, electrical, mechanical, and hybrid approaches (such as electro-chemical, optofluidic flow and photo-chemical methods. These methods are either lacking in desired spatial and temporal selectivity or require the introduction of invasive external factors. Within the last fifteen years however, several attractive guidance cues have been developed using purely light based cues to achieve axonal guidance. Here, we report a novel, purely optical repulsive guidance technique that uses low power, near infrared light, and demonstrates the guidance of primary goldfish retinal ganglion cell axons through turns of up to 120 degrees and over distances of ∼90 µm.

  15. Subtypes of GABAergic neurons project axons in the neocortex

    Directory of Open Access Journals (Sweden)

    Shigeyoshi Higo

    2009-11-01

    Full Text Available γ-aminobutyric acid (GABAergic neurons in the neocortex have been regarded as interneurons and speculated to modulate the activity of neurons locally. Recently, however, several experiments revealed that neuronal nitric oxide synthase (nNOS-positive GABAergic neurons project cortico-cortically with long axons. In this study, we illustrate Golgi-like images of the nNOS-positive GABAergic neurons using a nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d reaction and follow the emanating axon branches in cat brain sections. These axon branches projected cortico-cortically with other non-labeled arcuate fibers, contra-laterally via the corpus callosum and anterior commissure. The labeled fibers were not limited to the neocortex but found also in the fimbria of the hippocampus. In order to have additional information on these GABAergic neuron projections, we investigated green fluorescent protein (GFP-labeled GABAergic neurons in GAD67-Cre knock-in / GFP Cre-reporter mice. GFP-labeled axons emanate densely, especially in the fimbria, a small number in the anterior commissure, and very sparsely in the corpus callosum. These two different approaches confirm that not only nNOS-positive GABAergic neurons but also other subtypes of GABAergic neurons project long axons in the cerebral cortex and are in a position to be involved in information processing.

  16. Involvement of SARA in Axon and Dendrite Growth.

    Science.gov (United States)

    Arias, Cristina Isabel; Siri, Sebastián Omar; Conde, Cecilia

    2015-01-01

    SARA (Smad Anchor for Receptor Activation) plays a crucial role in Rab5-mediated endocytosis in cell lines localizing to early endosomes where it regulates morphology and function. Here, we analyzed the role of SARA during neuronal development and tested whether it functions as a regulator of endocytic trafficking of selected axonal and membrane proteins. Suppression of SARA perturbs the appearance of juxtanuclear endocytic recycling compartments and the neurons show long axons with large growth cones. Furthermore, surface distribution of the cell adhesion molecule L1 in axons and the fusion of vesicles containing transferring receptor (TfR) in dendrites were increased in neurons where SARA was silenced. Conversely, SARA overexpression generated large early endosomes and reduced neurite outgrowth. Taken together, our findings suggest a significant contribution of SARA to key aspects of neuronal development, including neurite formation. PMID:26405814

  17. Neurofilament proteins in axonal regeneration and neurodegenerative diseases

    Institute of Scientific and Technical Information of China (English)

    Haitao Wang; Minfei Wu; Chuanjun Zhan; Enyuan Ma; Maoguang Yang; Xiaoyu Yang; Yingpu Li

    2012-01-01

    Neurofilament protein is a component of the mature neuronal cytoskeleton, and it interacts with the zygosome, which is mediated by neurofilament-related proteins. Neurofilament protein regulates enzyme function and the structure of linker proteins. In addition, neurofilament gene expression plays an important role in nervous system development. Previous studies have shown that neurofilament gene transcriptional regulation is crucial for neurofilament protein expression, especially in axonal regeneration and degenerative diseases. Post-transcriptional regulation increased neurofilament protein gene transcription during axonal regeneration, ultimately resulting in a pattern of neurofilament protein expression. An expression imbalance of post-transcriptional regulatory proteins and other disorders could lead to amyotrophic lateral sclerosis or other neurodegenerative diseases. These findings indicated that after transcription, neurofilament protein regulated expression of related proteins and promoted regeneration of damaged axons, suggesting that regulation disorders could lead to neurodegenerative diseases.

  18. Motoneuron axon pathfinding errors in zebrafish: Differential effects related to concentration and timing of nicotine exposure

    Energy Technology Data Exchange (ETDEWEB)

    Menelaou, Evdokia; Paul, Latoya T. [Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803 (United States); Perera, Surangi N. [Joseph J. Zilber School of Public Health, University of Wisconsin — Milwaukee, Milwaukee, WI 53205 (United States); Svoboda, Kurt R., E-mail: svobodak@uwm.edu [Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803 (United States); Joseph J. Zilber School of Public Health, University of Wisconsin — Milwaukee, Milwaukee, WI 53205 (United States)

    2015-04-01

    Nicotine exposure during embryonic stages of development can affect many neurodevelopmental processes. In the developing zebrafish, exposure to nicotine was reported to cause axonal pathfinding errors in the later born secondary motoneurons (SMNs). These alterations in SMN axon morphology coincided with muscle degeneration at high nicotine concentrations (15–30 μM). Previous work showed that the paralytic mutant zebrafish known as sofa potato exhibited nicotine-induced effects onto SMN axons at these high concentrations but in the absence of any muscle deficits, indicating that pathfinding errors could occur independent of muscle effects. In this study, we used varying concentrations of nicotine at different developmental windows of exposure to specifically isolate its effects onto subpopulations of motoneuron axons. We found that nicotine exposure can affect SMN axon morphology in a dose-dependent manner. At low concentrations of nicotine, SMN axons exhibited pathfinding errors, in the absence of any nicotine-induced muscle abnormalities. Moreover, the nicotine exposure paradigms used affected the 3 subpopulations of SMN axons differently, but the dorsal projecting SMN axons were primarily affected. We then identified morphologically distinct pathfinding errors that best described the nicotine-induced effects on dorsal projecting SMN axons. To test whether SMN pathfinding was potentially influenced by alterations in the early born primary motoneuron (PMN), we performed dual labeling studies, where both PMN and SMN axons were simultaneously labeled with antibodies. We show that only a subset of the SMN axon pathfinding errors coincided with abnormal PMN axonal targeting in nicotine-exposed zebrafish. We conclude that nicotine exposure can exert differential effects depending on the levels of nicotine and developmental exposure window. - Highlights: • Embryonic nicotine exposure can specifically affect secondary motoneuron axons in a dose-dependent manner.

  19. [A clinical and pathological study of diffuse axonal injury].

    Science.gov (United States)

    Nakazawa, S; Kobayashi, S; Yokota, H; Shimura, T

    1989-03-01

    There is increasing evidence from human and experimental studies that the most important factor governing the outcome in head injury is the severity of diffuse axonal injuries. The authors have experienced 18 cases of severe diffuse axonal injury which showed post-traumatic coma for more than 24 hours and CT findings resembling those of shearing injuries of the cerebral white matter such as have been presented by Zimmerman et al. (1978). The consciousness levels on admission were 6 or less on the Glasgow Coma Scale and all cases were shown clinically to have primary brain stem injury. The main type of head trauma resulted from road traffic accidents (83%). Skull fractures were found in only 5 cases (28%). These findings suggested that acceleration/deceleration injury produce in the patients severe diffuse axonal injury. Initial ICP was below 20 mmHg in 11 cases out of 13 (85%). Parenchymal small hemorrhagic lesions of initial CT were basal ganglia (7 cases), corpus callosum (4 cases), pons (4 cases), midbrain (3 cases) and thalamus (2 cases). Extraparenchymal hemorrhagic lesions included intraventricular hemorrhage (6 cases) and subarachnoid hemorrhage (6 cases). Two autopsied cases of severe diffuse axonal injury (acute case and chronic case) showed remarkable congestion and edema in the deep part of the frontal white matter. Microscopic examination revealed marked axonal degeneration including axonal retraction ball in the corpus callosum, in the internal capsule and in the white matter of the brain stem. Glasgow Outcome Scale of the 18 patients at 3 months after the trauma made us concerned that no patients indicated good recovery or even only moderate disability.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2770962

  20. Axon-glial interactions in the central nervous system

    OpenAIRE

    Butt, Arthur; Bay, Virginia

    2011-01-01

    Axon-glial interactions are critical for brain information transmission and processing. In the CNS, this is a function of the major types of glia – astrocytes, oligodendrocytes and novel NG2-glia. This special issue of the Journal of Anatomy comprises contributions arising from a symposium entitled ‘Axon-glial interactions in the CNS’, held at the University of Portsmouth, UK in July 2010. The aim of the special issue is to bring together an international group of experts to demonstrate the c...

  1. A chloride channel in rat and human axons

    OpenAIRE

    Strupp, Michael; Grafe, Peter

    1991-01-01

    Current recordings from single chloride channels were obtained from excised and cell-attached patches of rat and human axons. In rat axons the channels showed an outwardly rectifying current-voltage relationship with a slope conductance of 33 pS at negative membrane potentials and 65 pS at positive potentials (symmetrical 150 mM CsCl). They were measurably for cations (PNa/PCs/PCl=0.1/0.2/1). Channel currents were independent of cytoplasmatic calcium concentration. Inactivation was not observ...

  2. Tuning the orchestra: transcriptional pathways controlling axon regeneration

    Directory of Open Access Journals (Sweden)

    Andrea Tedeschi

    2012-01-01

    Full Text Available Trauma in the adult mammalian central nervous system leads to irreversible structural and functional impairment due to failed regeneration attempts. In contrast, neurons in the peripheral nervous system exhibit a greater regenerative ability. It has been proposed that an orchestrated sequence of transcriptional events controlling the expression of specific sets of genes may be the underlying basis of an early cell-autonomous regenerative response. Understanding whether transcriptional fine tuning, in parallel with strategies aimed at counteracting extrinsic impediments promotes axon re-growth following central nervous system injuries represents an exciting challenge for future studies. Transcriptional pathways controlling axon regeneration are presented and discussed in this review.

  3. Networks of Polarized Actin Filaments in the Axon Initial Segment Provide a Mechanism for Sorting Axonal and Dendritic Proteins

    Directory of Open Access Journals (Sweden)

    Kaori Watanabe

    2012-12-01

    Full Text Available Trafficking of proteins specifically to the axonal or somatodendritic membrane allows neurons to establish and maintain polarized compartments with distinct morphology and function. Diverse evidence suggests that an actin-dependent vesicle filter within the axon initial segment (AIS plays a critical role in polarized trafficking; however, no distinctive actin-based structures capable of comprising such a filter have been found within the AIS. Here, using correlative light and scanning electron microscopy, we visualized networks of actin filaments several microns wide within the AIS of cortical neurons in culture. Individual filaments within these patches are predominantly oriented with their plus ends facing toward the cell body, consistent with models of filter selectivity. Vesicles carrying dendritic proteins are much more likely to stop in regions occupied by the actin patches than in other regions, indicating that the patches likely prevent movement of dendritic proteins to the axon and thereby act as a vesicle filter.

  4. Membrane potential dynamics of axons in cultured hippocampal neurons probed by second-harmonic-generation imaging

    Science.gov (United States)

    Nuriya, Mutsuo; Yasui, Masato

    2010-03-01

    The electrical properties of axons critically influence the nature of communication between neurons. However, due to their small size, direct measurement of membrane potential dynamics in intact and complex mammalian axons has been a challenge. Furthermore, quantitative optical measurements of axonal membrane potential dynamics have not been available. To characterize the basic principles of somatic voltage signal propagation in intact axonal arbors, second-harmonic-generation (SHG) imaging is applied to cultured mouse hippocampal neurons. When FM4-64 is applied extracellularly to dissociated neurons, whole axonal arbors are visualized by SHG imaging. Upon action potential generation by somatic current injection, nonattenuating action potentials are recorded in intact axonal arbors. Interestingly, however, both current- and voltage-clamp recordings suggest that nonregenerative subthreshold somatic voltage changes at the soma are poorly conveyed to these axonal sites. These results reveal the nature of membrane potential dynamics of cultured hippocampal neurons, and further show the possibility of SHG imaging in physiological investigations of axons.

  5. Axon diameter and intra-axonal volume fraction of the corticospinal tract in idiopathic normal pressure hydrocephalus measured by q-space imaging.

    Directory of Open Access Journals (Sweden)

    Kouhei Kamiya

    Full Text Available PURPOSE: Previous studies suggest that compression and stretching of the corticospinal tract (CST potentially cause treatable gait disturbance in patients with idiopathic normal pressure hydrocephalus (iNPH. Measurement of axon diameter with diffusion MRI has recently been used to investigate microstructural alterations in neurological diseases. In this study, we investigated alterations in the axon diameter and intra-axonal fraction of the CST in iNPH by q-space imaging (QSI analysis. METHODS: Nineteen patients with iNPH and 10 age-matched controls were recruited. QSI data were obtained with a 3-T system by using a single-shot echo planar imaging sequence with the diffusion gradient applied parallel to the antero-posterior axis. By using a two-component low-q fit model, the root mean square displacements of intra-axonal space ( =  axon diameter and intra-axonal volume fraction of the CST were calculated at the levels of the internal capsule and body of the lateral ventricle, respectively. RESULTS: Wilcoxon's rank-sum test revealed a significant increase in CST intra-axonal volume fraction at the paraventricular level in patients (p<0.001, whereas no significant difference was observed in the axon diameter. At the level of the internal capsule, neither axon diameter nor intra-axonal volume fraction differed significantly between the two groups. CONCLUSION: Our results suggest that in patients with iNPH, the CST does not undergo irreversible axonal damage but is rather compressed and/or stretched owing to pressure from the enlarged ventricle. These analyses of axon diameter and intra-axonal fraction yield insights into microstructural alterations of the CST in iNPH.

  6. Synapses formed by identified retinogeniculate axons during the segregation of eye input.

    OpenAIRE

    Campbell, G; Shatz, C J

    1992-01-01

    The synaptic organization of identified retinogeniculate axons was studied during the prenatal development of eye-specific layers in the LGN of the cat. During this period, retinogeniculate axons undergo stereotyped morphological changes. Retinogeniculate axons originating from one eye and passing through LGN territory destined to be solely innervated by the other eye (inappropriate territory) initially give rise to many side branches. As the eye-specific layers emerge, these axons elaborate ...

  7. Differential Axonal Projection of Mitral and Tufted Cells in the Mouse Main Olfactory System

    Directory of Open Access Journals (Sweden)

    Shin Nagayama

    2010-09-01

    Full Text Available In the past decade, much has been elucidated regarding the functional organization of the axonal connection of olfactory sensory neurons to olfactory bulb (OB glomeruli. However, the manner in which projection neurons of the OB process odorant input and send this information to higher brain centers remains unclear. Here, we report long-range, large-scale tracing of the axonal projection patterns of OB neurons using two-photon microscopy. Tracer injection into a single glomerulus demonstrated widely distributed mitral/tufted cell axonal projections on the lateroventral surface of the mouse brain, including the anterior/posterior piriform cortex (PC and olfactory tubercle (OT. We noted two distinct groups of labeled axons: PC-orienting axons and OT-orienting axons. Each group occupied distinct parts of the lateral olfactory tract. PC-orienting axons projected axon collaterals to a wide area of the PC but only a few collaterals to the OT. OT-orienting axons densely projected axon collaterals primarily to the anterolateral OT (alOT. Different colored dye injections into the superficial and deep portions of the OB external plexiform layer revealed that the PC-orienting axon populations originated in presumed mitral cells and the OT-orienting axons in presumed tufted cells. These data suggest that although mitral and tufted cells receive similar odor signals from a shared glomerulus, they process the odor information in different ways and send their output to different higher brain centers via the PC and alOT.

  8. Traction Force and Tension Fluctuations During Axon Growth

    Directory of Open Access Journals (Sweden)

    Jamison ePolackwich

    2015-10-01

    Full Text Available Actively generated mechanical forces play a central role in axon growthand guidance, but the mechanisms that underly force generation andregulation in growing axons remain poorly understood. We reportmeasurements of the dynamics of traction stresses from growth cones ofactively advancing axons from postnatal rat DRG neurons. By tracking themovement of the growth cone and analyzing the traction stress field froma reference frame that moves with it, we are able to show that there isa clear and consistent average stress field that underlies the complexspatial stresses present at any one time. The average stress field hasstrong maxima on the sides of the growth cone, directed inward towardthe growth cone neck. This pattern represents a contractile stresscontained within the growth cone, and a net force that is balanced bythe axon tension. Using high time-resolution measurements of the growthcone traction stresses, we show that the stress field is composed offluctuating local stress peaks, with a large number peaks that live fora short time, a population of peaks whose lifetime distribution followsan exponential decay, and a small number of very long-lived peaks. Weshow that the high time-resolution data also reveal that the tensionappears to vary randomly over short time scales, roughly consistent withthe lifetime of the stress peaks, suggesting that the tensionfluctuations originate from stochastic adhesion dynamics.

  9. Model of fasciculation and sorting in mixed populations of axons

    Czech Academy of Sciences Publication Activity Database

    Chaudhuri, D.; Borowski, P.; Zápotocký, Martin

    2011-01-01

    Roč. 84, č. 2 (2011), e021908. ISSN 1539-3755 R&D Projects: GA MŠk(CZ) LC554 Institutional research plan: CEZ:AV0Z50110509 Keywords : axon guidance * neurogenesis * mathematical model Subject RIV: FH - Neurology Impact factor: 2.255, year: 2011

  10. Spectrins in axonal cytoskeletons: Dynamics revealed by extensions and fluctuations

    Science.gov (United States)

    Lai, Lipeng; Cao, Jianshu

    2014-07-01

    The macroscopic properties, the properties of individual components, and how those components interact with each other are three important aspects of a composited structure. An understanding of the interplay between them is essential in the study of complex systems. Using axonal cytoskeleton as an example system, here we perform a theoretical study of slender structures that can be coarse-grained as a simple smooth three-dimensional curve. We first present a generic model for such systems based on the fundamental theorem of curves. We use this generic model to demonstrate the applicability of the well-known worm-like chain (WLC) model to the network level and investigate the situation when the system is stretched by strong forces (weakly bending limit). We specifically studied recent experimental observations that revealed the hitherto unknown periodic cytoskeleton structure of axons and measured the longitudinal fluctuations. Instead of focusing on single molecules, we apply analytical results from the WLC model to both single molecule and network levels and focus on the relations between extensions and fluctuations. We show how this approach introduces constraints to possible local dynamics of the spectrin tetramers in the axonal cytoskeleton and finally suggests simple but self-consistent dynamics of spectrins in which the spectrins in one spatial period of axons fluctuate in-sync.

  11. PTEN inhibition and axon regeneration and neural repair

    Institute of Scientific and Technical Information of China (English)

    Yosuke Ohtake; Umar Hayat; Shuxin Li

    2015-01-01

    The intrinsic growth ability of all the neurons declines during development although some may grow better than others. Numerous intracellular signaling proteins and transcription factors have been shown to regulate the intrinsic growth capacity in mature neurons. Among them, PI3 kinase/Akt pathway is important for controlling axon elongation. As a negative regulator of this pathway, the tumor suppressor phosphatase and tensin homolog (PTEN) appears critical to con-trol the regenerative ability of young and adult neurons. This review will focus on recent research progress in axon regeneration and neural repair by PTEN inhibition and therapeutic potential of blocking this phosphatase for neurological disorders. Inhibition of PTEN by deletion in con-ditional knockout mice, knockdown by short-hairpin RNA, or blockade by pharmacological approaches, including administration of selective PTEN antagonist peptides, stimulates various degrees of axon regrowth in juvenile or adult rodents with central nervous system injuries. Im-portantly, post-injury PTEN suppression could enhance axonal growth and functional recovery in adult central nervous system after injury.

  12. β₂-adrenergic receptors protect axons during energetic stress but do not influence basal glio-axonal lactate shuttling in mouse white matter.

    Science.gov (United States)

    Laureys, G; Valentino, M; Demol, F; Zammit, C; Muscat, R; Cambron, M; Kooijman, R; De Keyser, J

    2014-09-26

    In vitro studies have demonstrated that β2-adrenergic receptor activation stimulates glycogen degradation in astrocytes, generating lactate as a potential energy source for neurons. Using in vivo microdialysis in mouse cerebellar white matter we demonstrate continuous axonal lactate uptake and glial-axonal metabolic coupling of glutamate/lactate exchange. However, this physiological lactate production was not influenced by activation (clenbuterol) or blocking (ICI 118551) of β2-adrenergic receptors. In two-photon imaging experiments on ex vivo mouse corpus callosum subjected to aglycemia, β2-adrenergic activation rescued axons, whereas inhibition of axonal lactate uptake by α-cyano-4-hydroxycinnamic acid (4-CIN) was associated with severe axonal loss. Our results suggest that axonal protective effects of glial β2-adrenergic receptor activation are not mediated by enhanced lactate production. PMID:25064060

  13. IH activity is increased in populations of slow versus fast motor axons of the rat.

    Directory of Open Access Journals (Sweden)

    Chad eLorenz

    2014-09-01

    Full Text Available Much is known about the electrophysiological variation in motoneuron somata across different motor units. However comparatively less is known about electrophysiological variation in motor axons and how this could impact function or electrodiagnosis in healthy or diseased states. We performed nerve excitability testing on two groups of motor axons in Sprague-Dawley rats that are known to differ significantly in their chronic daily activity patterns and in the relative proportion of motor unit types: one group innervating the soleus (slow motor axons and the other group innervating the tibialis anterior (fast motor axons muscles. We found that slow motor axons have significantly larger accommodation compared to fast motor axons upon application of a 100 ms hyperpolarizing conditioning stimulus that is 40% of axon threshold (Z = 3.24, p = 0.001 or 20% of axon threshold (Z = 2.67, p = 0.008. Slow motor axons had larger accommodation to hyperpolarizing currents in the current-threshold measurement (-80% Z = 3.07, p = 0.002; -90% Z = 2.98, p = 0.003. In addition, we found that slow motor axons have a significantly smaller rheobase than fast motor axons (Z = -1.99, p = 0.047 accompanied by a lower threshold in stimulus-response curves. The results provide evidence that slow motor axons have greater activity of the hyperpolarization-activated inwardly rectifying cation conductance (IH than fast motor axons. It is possible that this difference between fast and slow axons is caused by an adaptation to their chronic differences in daily activity patterns, and that this adaptation might have a functional effect on the motor unit. Moreover, these findings indicate that slow and fast motor axons may react differently to pathological conditions.

  14. White matter involvement after TBI: Clues to axon and myelin repair capacity.

    Science.gov (United States)

    Armstrong, Regina C; Mierzwa, Amanda J; Marion, Christina M; Sullivan, Genevieve M

    2016-01-01

    Impact-acceleration forces to the head cause traumatic brain injury (TBI) with damage in white matter tracts comprised of long axons traversing the brain. White matter injury after TBI involves both traumatic axonal injury (TAI) and myelin pathology that evolves throughout the post-injury time course. The axon response to initial mechanical forces and secondary insults follows the process of Wallerian degeneration, which initiates as a potentially reversible phase of intra-axonal damage and proceeds to an irreversible phase of axon fragmentation. Distal to sites of axon disconnection, myelin sheaths remain for prolonged periods, which may activate neuroinflammation and inhibit axon regeneration. In addition to TAI, TBI can cause demyelination of intact axons. These evolving features of axon and myelin pathology also represent opportunities for repair. In experimental TBI, demyelinated axons exhibit remyelination, which can serve to both protect axons and facilitate recovery of function. Myelin remodeling may also contribute to neuroplasticity. Efficient clearance of myelin debris is a potential target to attenuate the progression of chronic pathology. During the early phase of Wallerian degeneration, interventions that prevent the transition from reversible damage to axon disconnection warrant the highest priority, based on the poor regenerative capacity of axons in the CNS. Clinical evaluation of TBI will need to address the challenge of accurately detecting the extent and stage of axon damage. Distinguishing the complex white matter changes associated with axons and myelin is necessary for interpreting advanced neuroimaging approaches and for identifying a broader range of therapeutic opportunities to improve outcome after TBI. PMID:25697845

  15. Axonal regeneration and development of de novo axons from distal dendrites of adult feline commissural interneurons after a proximal axotomy

    DEFF Research Database (Denmark)

    Fenrich, Keith K; Skelton, Nicole; MacDermid, Victoria E;

    2007-01-01

    Following proximal axotomy, several types of neurons sprout de novo axons from distal dendrites. These processes may represent a means of forming new circuits following spinal cord injury. However, it is not know whether mammalian spinal interneurons, axotomized as a result of a spinal cord injur...

  16. The progressive nature of Wallerian degeneration in wild-type and slow Wallerian degeneration (WldS nerves

    Directory of Open Access Journals (Sweden)

    Grumme Daniela S

    2005-02-01

    in which clearance of trophic or regulatory factors by axonal transport triggers degeneration. WldS axons, once they finally degenerate, do so by a fundamentally different mechanism, indicated by differences in the rate, direction and abruptness of progression, and by different early morphological signs of degeneration. These observations suggest that WldS axons undergo a slow anterograde decay as axonal components are gradually depleted, and do not simply follow the degeneration pathway of wild-type axons at a slower rate.

  17. Alterations of mitochondrial dynamics allow retrograde propagation of locally initiated axonal insults.

    Science.gov (United States)

    Lassus, Benjamin; Magifico, Sebastien; Pignon, Sandra; Belenguer, Pascale; Miquel, Marie-Christine; Peyrin, Jean-Michel

    2016-01-01

    In chronic neurodegenerative syndromes, neurons progressively die through a generalized retraction pattern triggering retrograde axonal degeneration toward the cell bodies, which molecular mechanisms remain elusive. Recent observations suggest that direct activation of pro-apoptotic signaling in axons triggers local degenerative events associated with early alteration of axonal mitochondrial dynamics. This raises the question of the role of mitochondrial dynamics on both axonal vulnerability stress and their implication in the spreading of damages toward unchallenged parts of the neuron. Here, using microfluidic chambers, we assessed the consequences of interfering with OPA1 and DRP1 proteins on axonal degeneration induced by local application of rotenone. We found that pharmacological inhibition of mitochondrial fission prevented axonal damage induced by rotenone, in low glucose conditions. While alteration of mitochondrial dynamics per se did not lead to spontaneous axonal degeneration, it dramatically enhanced axonal vulnerability to rotenone, which had no effect in normal glucose conditions, and promoted retrograde spreading of axonal degeneration toward the cell body. Altogether, our results suggest a mitochondrial priming effect in axons as a key process of axonal degeneration. In the context of neurodegenerative diseases, like Parkinson's and Alzheimer's, mitochondria fragmentation could hasten neuronal death and initiate spatial dispersion of locally induced degenerative events. PMID:27604820

  18. The role of T-cadherin in axonal pathway formation in neocortical circuits.

    Science.gov (United States)

    Hayano, Yuki; Zhao, Hong; Kobayashi, Hiroaki; Takeuchi, Kosei; Norioka, Shigemi; Yamamoto, Nobuhiko

    2014-12-01

    Cortical efferent and afferent fibers are arranged in a stereotyped pattern in the intermediate zone (IZ). Here, we studied the mechanism of axonal pathway formation by identifying a molecule that is expressed in a subset of cortical axons in the rat. We found that T-cadherin (T-cad), a member of the cadherin family, is expressed in deep-layer cell axons projecting to subcortical structures, but not in upper layer callosal axons projecting to the contralateral cortex. Ectopic expression of T-cad in upper layer cells induced axons to project toward subcortical structures via the upper part of the IZ. Moreover, the axons of deep-layer cells in which T-cad expression was suppressed by RNAi projected towards the contralateral cortex via an aberrant route. These results suggest that T-cad is involved in axonal pathway formation in the developing cortex. PMID:25468941

  19. Neuropathological changes of rabbit spinal motor neurons induced by retrograde axonal aluminum-uptake

    International Nuclear Information System (INIS)

    To examine pathological changes of spinal motor neurons induced by subepineurial injection of 10-500 μ1 of 2% AlCl3 solution into a sciatic nerve of rabbits, histometric studies of chromatolytic neurons, spheroids/globules and degenerative neurons in the both lumbar anterior gray horn tissues was undertaken using routine and immunochemical staining methods. All these neuronal changes were reactive to the antineurofilament antibody (SM1). Except chromatolytic neurons, the appearance of spheroids/globules and degenerative neurons were significantly dose-responsive to the volume of injected 2% AlCl3 solution. In this acute experiments, it is suggested that Al may primarily cause a disturbance of neurofilament transport in proximal axons, consequently leading to neurofibrillary degeneration of neurons. (author)

  20. Axonal degeneration affects muscle density in older men and women.

    Science.gov (United States)

    Lauretani, Fulvio; Bandinelli, Stefania; Bartali, Benedetta; Di Iorio, Angelo; Giacomini, Vittoria; Corsi, Anna Maria; Guralnik, Jack M; Ferrucci, Luigi

    2006-08-01

    Using data from InCHIANTI, a prospective population-based survey of older persons, we examined the relationship of peroneal nerve conduction velocity (NCV, a measure of nerve myelination) and compound muscle action potential (CMAP, a measure of axonal degeneration) with calf muscle mass and density, two complementary measures of sarcopenia. NCV and CMAP were assessed by surface electroneurography of the right peroneal nerve conducted in 1162 participants, 515 men and 647 women, age 21-96 years, free of major neurological diseases. Cross-sectional muscle area and calf muscle density were measured using peripheral quantitative computerized tomography (pQCT). Both nerve and muscle parameters declined with age although in most cases the decline was not linear. In both sexes, CMAP, but not NCV, was independently and significantly associated with calf muscle density. These findings suggest that intrinsic changes in the muscle tissue are partially caused by a reduction in the number of motor axons. PMID:16085338

  1. Missed connections: photoreceptor axon seeks target neuron for synaptogenesis.

    Science.gov (United States)

    Astigarraga, Sergio; Hofmeyer, Kerstin; Treisman, Jessica E

    2010-08-01

    Extending axons must choose the appropriate synaptic target cells in order to assemble functional neural circuitry. The axons of the Drosophila color-sensitive photoreceptors R7 and R8 project as a single fascicle from each ommatidium, but their terminals are segregated into distinct layers within their target region. Recent studies have begun to reveal the molecular mechanisms that establish this projection pattern. Both homophilic adhesion molecules and specific ligand-receptor interactions make important contributions to stabilizing R7 and R8 terminals in the appropriate target layers. These cell recognition molecules are regulated by the same transcription factors that control R7 and R8 cell fates. Autocrine and repulsive signaling mechanisms prevent photoreceptor terminals from encroaching on their neighbors, preserving the spatial resolution of visual information. PMID:20434326

  2. Bazooka mediates secondary axon morphology in Drosophila brain lineages

    OpenAIRE

    Hartenstein Volker; Spindler Shana R

    2011-01-01

    Abstract In the Drosophila brain, neural lineages project bundled axon tracts into a central neuropile. Each lineage exhibits a stereotypical branching pattern and trajectory, which distinguish it from other lineages. In this study, we used a multilineage approach to explore the neural function of the Par-complex member Par3/Bazooka in vivo. Drosophila bazooka is expressed in post-mitotic neurons of the larval brain and localizes within neurons in a lineage-dependent manner. The fact that mul...

  3. Giant axonal neuropathy: observations on a further patient.

    OpenAIRE

    Donaghy, M; Brett, E M; Ormerod, I E; King, R H; Thomas, P. K.

    1988-01-01

    A further child with giant axonal neuropathy (GAN), abnormally curly hair and consanguineous parents is described. Of the 19 patients with GAN so far reported in the literature, six, including the present patient, have resulted from consanguineous marriages. This makes autosomal recessive inheritance of GAN highly probable. Our patient also exhibited cerebellar ataxia and signs of pyramidal tract damage; magnetic resonance brain imaging demonstrated abnormalities within the cerebellar and cer...

  4. Craniocerebral trauma. Magnetic resonance imaging of diffuse axonal injury

    International Nuclear Information System (INIS)

    Acceleration-deceleration rotational brain trauma is a common cause of disability or death in young adults and often leads to a focal destruction of axons. The resulting pathology, axonal shear injury is referred to as diffuse axonal injury (DAI). The DAI-associated lesions occur bilaterally, are widely dispersed and have been observed in the surface and deep white matter. They are found near to and far from the impact site. When DAI is clinically suspected, magnetic resonance imaging (MRI) is the method of choice for further clarification, especially in patients where cranial computed tomography (CT) is inconspicuous. To investigate the presence of DAI after traumatic brain injury (TBI), a multimodal MRI approach is applied including the common structural and also functional imaging sequences. For structural MRI, fluid-attenuated inversion recovery (FLAIR) weighted and susceptibility contrast imaging (SWI) are the sequences mainly used. The SWI technique is extremely sensitive to blood breakdown products, which appear as small signal voids at three locations, at the gray-white interface, in the corpus callosum and in the brain stem. Functional MRI comprises a group of constantly developing techniques that have great potential in optimal evaluation of the white matter in patients after craniocerebral trauma. These imaging techniques allow the visualization of changes associated with shear injuries, such as functional impairment of axons and decreased blood flow and abnormal metabolic activity of the brain parts affected. The multimodal MRI approach in patients with DAI results in a more detailed and differentiated representation of the underlying pathophysiological changes of the injured nerve tracts and helps to improve the diagnostic and prognostic accuracy of MRI. When DAI is suspected multimodal MRI should be performed as soon as possible after craniocerebral injury. (orig.)

  5. Estimating neuronal connectivity from axonal and dendritic density fields

    Directory of Open Access Journals (Sweden)

    Jaap evan Pelt

    2013-11-01

    Full Text Available Neurons innervate space by extending axonal and dendritic arborizations. When axons and dendrites come in close proximity of each other, synapses between neurons can be formed. Neurons vary greatly in their morphologies and synaptic connections with other neurons. The size and shape of the arborizations determine the way neurons innervate space. A neuron may therefore be characterized by the spatial distribution of its axonal and dendritic 'mass'. A population mean 'mass' density field of a particular neuron type can be obtained by averaging over the individual variations in neuron geometries. Connectivity in terms of candidate synaptic contacts between neurons can be determined directly on the basis of their arborizations but also indirectly on the basis of their density fields. To decide when a candidate synapse can be formed, we previously developed a criterion defining that axonal and dendritic line pieces should cross in 3D and have an orthogonal distance less than a threshold value. In this paper, we developed new methodology for applying this criterion to density fields. We show that estimates of the number of contacts between neuron pairs calculated from their density fields are fully consistent with the number of contacts calculated from the actual arborizations. However, the estimation of the connection probability and the expected number of contacts per connection cannot be calculated directly from density fields, because density fields do not carry anymore the correlative structure in the spatial distribution of synaptic contacts. Alternatively, these two connectivity measures can be estimated from the expected number of contacts by using empirical mapping functions. The neurons used for the validation studies were generated by our neuron simulator NETMORPH. An example is given of the estimation of average connectivity and Euclidean pre- and postsynaptic distance distributions in a network of neurons represented by their population

  6. Abnormal Corticospinal Excitability in Traumatic Diffuse Axonal Brain Injury

    OpenAIRE

    Bernabeu, Montse; Demirtas-Tatlidede, Asli; Opisso, Eloy; Lopez, Raquel; Tormos, Jose Mª; Pascual-Leone, Alvaro

    2009-01-01

    This study aimed to investigate the cortical motor excitability characteristics in diffuse axonal injury (DAI) due to severe traumatic brain injury (TBI). A variety of excitatory and inhibitory transcranial magnetic stimulation (TMS) paradigms were applied to primary motor cortices of 17 patients and 11 healthy controls. The parameters of testing included resting motor threshold (MT), motor evoked potential (MEP) area under the curve, input-output curves, MEP variability, and silent period (S...

  7. Voluntary exercise increases axonal regeneration from sensory neurons

    OpenAIRE

    Molteni, Raffaella; Zheng, Jun-Qi; Ying, Zhe; Gómez-Pinilla, Fernando; Twiss, Jeffery L

    2004-01-01

    Recent advances in understanding the role of neurotrophins on activity-dependent plasticity have provided insight into how behavior can affect specific aspects of neuronal biology. We present evidence that voluntary exercise can prime adult dorsal root ganglion neurons for increased axonal regeneration through a neurotrophin-dependent mechanism. Dorsal root ganglion neurons showed an increase in neurite outgrowth when cultured from animals that had undergone 3 or 7 days of exercise compared w...

  8. Adult motor axons preferentially reinnervate predegenerated muscle nerve

    OpenAIRE

    M. Abdullah; O'Daly, A.; A Vyas; Rohde, C.; Brushart, T.M.

    2013-01-01

    Preferential motor reinnervation (PMR) is the tendency for motor axons regenerating after repair of mixed nerve to reinnervate muscle nerve and/or muscle rather than cutaneous nerve or skin. PMR may occur in response to the peripheral nerve pathway alone in juvenile rats (Brushart, 1993; Redett et al., 2005), yet the ability to identify and respond to specific pathway markers is reportedly lost in adults (Uschold et al., 2007). The experiments reported here evaluate the relative roles of path...

  9. White matter microstructure from nonparametric axon diameter distribution mapping.

    Science.gov (United States)

    Benjamini, Dan; Komlosh, Michal E; Holtzclaw, Lynne A; Nevo, Uri; Basser, Peter J

    2016-07-15

    We report the development of a double diffusion encoding (DDE) MRI method to estimate and map the axon diameter distribution (ADD) within an imaging volume. A variety of biological processes, ranging from development to disease and trauma, may lead to changes in the ADD in the central and peripheral nervous systems. Unlike previously proposed methods, this ADD experimental design and estimation framework employs a more general, nonparametric approach, without a priori assumptions about the underlying form of the ADD, making it suitable to analyze abnormal tissue. In the current study, this framework was used on an ex vivo ferret spinal cord, while emphasizing the way in which the ADD can be weighted by either the number or the volume of the axons. The different weightings, which result in different spatial contrasts, were considered throughout this work. DDE data were analyzed to derive spatially resolved maps of average axon diameter, ADD variance, and extra-axonal volume fraction, along with a novel sub-micron restricted structures map. The morphological information contained in these maps was then used to segment white matter into distinct domains by using a proposed k-means clustering algorithm with spatial contiguity and left-right symmetry constraints, resulting in identifiable white matter tracks. The method was validated by comparing histological measures to the estimated ADDs using a quantitative similarity metric, resulting in good agreement. With further acquisition acceleration and experimental parameters adjustments, this ADD estimation framework could be first used preclinically, and eventually clinically, enabling a wide range of neuroimaging applications for improved understanding of neurodegenerative pathologies and assessing microstructural changes resulting from trauma. PMID:27126002

  10. Retinal glia promote dorsal root ganglion axon regeneration.

    Directory of Open Access Journals (Sweden)

    Barbara Lorber

    Full Text Available Axon regeneration in the adult central nervous system (CNS is limited by several factors including a lack of neurotrophic support. Recent studies have shown that glia from the adult rat CNS, specifically retinal astrocytes and Müller glia, can promote regeneration of retinal ganglion cell axons. In the present study we investigated whether retinal glia also exert a growth promoting effect outside the visual system. We found that retinal glial conditioned medium significantly enhanced neurite growth and branching of adult rat dorsal root ganglion neurons (DRG in culture. Furthermore, transplantation of retinal glia significantly enhanced regeneration of DRG axons past the dorsal root entry zone after root crush in adult rats. To identify the factors that mediate the growth promoting effects of retinal glia, mass spectrometric analysis of retinal glial conditioned medium was performed. Apolipoprotein E and secreted protein acidic and rich in cysteine (SPARC were found to be present in high abundance, a finding further confirmed by western blotting. Inhibition of Apolipoprotein E and SPARC significantly reduced the neuritogenic effects of retinal glial conditioned medium on DRG in culture, suggesting that Apolipoprotein E and SPARC are the major mediators of this regenerative response.

  11. EEG functional connectivity, axon delays and white matter disease

    Science.gov (United States)

    Nunez, Paul L.; Srinivasan, Ramesh; Fields, R. Douglas

    2016-01-01

    Objective Both structural and functional brain connectivities are closely linked to white matter disease. We discuss several such links of potential interest to neurologists, neurosurgeons, radiologists, and non-clinical neuroscientists. Methods Treatment of brains as genuine complex systems suggests major emphasis on the multi-scale nature of brain connectivity and dynamic behavior. Cross-scale interactions of local, regional, and global networks are apparently responsible for much of EEG's oscillatory behaviors. Finite axon propagation speed, often assumed to be infinite in local network models, is central to our conceptual framework. Results Myelin controls axon speed, and the synchrony of impulse traffic between distant cortical regions appears to be critical for optimal mental performance and learning. Results Several experiments suggest that axon conduction speed is plastic, thereby altering the regional and global white matter connections that facilitate binding of remote local networks. Conclusions Combined EEG and high resolution EEG can provide distinct multi-scale estimates of functional connectivity in both healthy and diseased brains with measures like frequency and phase spectra, covariance, and coherence. Significance White matter disease may profoundly disrupt normal EEG coherence patterns, but currently these kinds of studies are rare in scientific labs and essentially missing from clinical environments. PMID:24815984

  12. Axonal Dysfunction Precedes Motor Neuronal Death in Amyotrophic Lateral Sclerosis.

    Directory of Open Access Journals (Sweden)

    Yuta Iwai

    Full Text Available Wide-spread fasciculations are a characteristic feature in amyotrophic lateral sclerosis (ALS, suggesting motor axonal hyperexcitability. Previous excitability studies have shown increased nodal persistent sodium conductances and decreased potassium currents in motor axons of ALS patients, both of the changes inducing hyperexcitability. Altered axonal excitability potentially contributes to motor neuron death in ALS, but the relationship of the extent of motor neuronal death and abnormal excitability has not been fully elucidated. We performed multiple nerve excitability measurements in the median nerve at the wrist of 140 ALS patients and analyzed the relationship of compound muscle action potential (CMAP amplitude (index of motor neuronal loss and excitability indices, such as strength-duration time constant, threshold electrotonus, recovery cycle and current-threshold relationships. Compared to age-matched normal controls (n = 44, ALS patients (n = 140 had longer strength-duration time constant (SDTC: a measure of nodal persistent sodium current; p 5mV. Regression analyses showed that SDTC (R = -0.22 and depolarizing threshold electrotonus (R = -0.22 increased with CMAP decline. These findings suggest that motor nerve hyperexcitability occurs in the early stage of the disease, and precedes motor neuronal loss in ALS. Modulation of altered ion channel function could be a treatment option for ALS.

  13. Axonal Dysfunction Precedes Motor Neuronal Death in Amyotrophic Lateral Sclerosis.

    Science.gov (United States)

    Iwai, Yuta; Shibuya, Kazumoto; Misawa, Sonoko; Sekiguchi, Yukari; Watanabe, Keisuke; Amino, Hiroshi; Kuwabara, Satoshi

    2016-01-01

    Wide-spread fasciculations are a characteristic feature in amyotrophic lateral sclerosis (ALS), suggesting motor axonal hyperexcitability. Previous excitability studies have shown increased nodal persistent sodium conductances and decreased potassium currents in motor axons of ALS patients, both of the changes inducing hyperexcitability. Altered axonal excitability potentially contributes to motor neuron death in ALS, but the relationship of the extent of motor neuronal death and abnormal excitability has not been fully elucidated. We performed multiple nerve excitability measurements in the median nerve at the wrist of 140 ALS patients and analyzed the relationship of compound muscle action potential (CMAP) amplitude (index of motor neuronal loss) and excitability indices, such as strength-duration time constant, threshold electrotonus, recovery cycle and current-threshold relationships. Compared to age-matched normal controls (n = 44), ALS patients (n = 140) had longer strength-duration time constant (SDTC: a measure of nodal persistent sodium current; p CMAP (> 5mV). Regression analyses showed that SDTC (R = -0.22) and depolarizing threshold electrotonus (R = -0.22) increased with CMAP decline. These findings suggest that motor nerve hyperexcitability occurs in the early stage of the disease, and precedes motor neuronal loss in ALS. Modulation of altered ion channel function could be a treatment option for ALS. PMID:27383069

  14. Sensory axon-derived neuregulin-1 is required for axoglial signaling and normal sensory function but not for long-term axon maintenance

    DEFF Research Database (Denmark)

    Fricker, F.R.; Zhu, N.; Tsantoulas, C.;

    2009-01-01

    " pockets. The total number of axons in the sural nerve was unchanged, but a greater proportion was unmyelinated. In addition, we observed large-diameter axons that were in a 1:1 relationship with Schwann cells, surrounded by a basal lamina but not myelinated. There was no evidence of DRG or Schwann cell...

  15. Regulation of action potential waveforms by axonal GABAA receptors in cortical pyramidal neurons.

    Directory of Open Access Journals (Sweden)

    Yang Xia

    Full Text Available GABAA receptors distributed in somatodendritic compartments play critical roles in regulating neuronal activities, including spike timing and firing pattern; however, the properties and functions of GABAA receptors at the axon are still poorly understood. By recording from the cut end (bleb of the main axon trunk of layer -5 pyramidal neurons in prefrontal cortical slices, we found that currents evoked by GABA iontophoresis could be blocked by picrotoxin, indicating the expression of GABAA receptors in axons. Stationary noise analysis revealed that single-channel properties of axonal GABAA receptors were similar to those of somatic receptors. Perforated patch recording with gramicidin revealed that the reversal potential of the GABA response was more negative than the resting membrane potential at the axon trunk, suggesting that GABA may hyperpolarize the axonal membrane potential. Further experiments demonstrated that the activation of axonal GABAA receptors regulated the amplitude and duration of action potentials (APs and decreased the AP-induced Ca2+ transients at the axon. Together, our results indicate that the waveform of axonal APs and the downstream Ca2+ signals are modulated by axonal GABAA receptors.

  16. Irregular geometries in normal unmyelinated axons: a 3D serial EM analysis.

    Science.gov (United States)

    Greenberg, M M; Leitao, C; Trogadis, J; Stevens, J K

    1990-12-01

    Axons have generally been represented as straight cylinders. It is not at all uncommon for anatomists to take single cross-sections of an axonal bundle, and from the axonal diameter compute expected conduction velocities. This assumes that each cross-section represents a slice through a perfect cylinder. We have examined the three-dimensional geometry of 98 central and peripheral unmyelinated axons, using computer-assisted serial electron microscopy. These reconstructions reveal that virtually all unmyelinated axons have highly irregular axial shapes consisting of periodic varicosities. The varicosities were, without exception, filled with membranous organelles frequently including mitochondria, and have obligatory volumes similar to that described in other neurites. The mitochondria make contact with microtubules, while the other membraneous organelles were frequently found free floating in the cytoplasm. We conclude that unmyelinated axons are fundamentally varicose structures created by the presence of organelles, and that an axon's calibre is dynamic in both space and time. These irregular axonal geometries raise serious doubts about standard two dimensional morphometric analysis and suggest that electrical properties may be more heterogeneous than expected from single section data. These results also suggest that the total number of microtubules contained in an axon, rather than its single section diameter, may prove to be a more accurate predictor of properties such as conduction velocity. Finally, these results offer an explanation for a number of pathological changes that have been described in unmyelinated axons. PMID:2292722

  17. Soluble axoplasm enriched from injured CNS axons reveals the early modulation of the actin cytoskeleton.

    Directory of Open Access Journals (Sweden)

    Patrick Garland

    Full Text Available Axon injury and degeneration is a common consequence of diverse neurological conditions including multiple sclerosis, traumatic brain injury and spinal cord injury. The molecular events underlying axon degeneration are poorly understood. We have developed a novel method to enrich for axoplasm from rodent optic nerve and characterised the early events in Wallerian degeneration using an unbiased proteomics screen. Our detergent-free method draws axoplasm into a dehydrated hydrogel of the polymer poly(2-hydroxyethyl methacrylate, which is then recovered using centrifugation. This technique is able to recover axonal proteins and significantly deplete glial contamination as confirmed by immunoblotting. We have used iTRAQ to compare axoplasm-enriched samples from naïve vs injured optic nerves, which has revealed a pronounced modulation of proteins associated with the actin cytoskeleton. To confirm the modulation of the actin cytoskeleton in injured axons we focused on the RhoA pathway. Western blotting revealed an augmentation of RhoA and phosphorylated cofilin in axoplasm-enriched samples from injured optic nerve. To investigate the localisation of these components of the RhoA pathway in injured axons we transected axons of primary hippocampal neurons in vitro. We observed an early modulation of filamentous actin with a concomitant redistribution of phosphorylated cofilin in injured axons. At later time-points, RhoA is found to accumulate in axonal swellings and also colocalises with filamentous actin. The actin cytoskeleton is a known sensor of cell viability across multiple eukaryotes, and our results suggest a similar role for the actin cytoskeleton following axon injury. In agreement with other reports, our data also highlights the role of the RhoA pathway in axon degeneration. These findings highlight a previously unexplored area of axon biology, which may open novel avenues to prevent axon degeneration. Our method for isolating CNS axoplasm

  18. Biochemical analysis of PIFTC3, the Trypanosoma brucei ortholog of nematode DYF-13, reveals interactions with established and putative intraflagellar transport components

    OpenAIRE

    Franklin, Joseph B.; Ullu, Elisabetta

    2010-01-01

    DYF-13, originally identified in C. elegans within a collection of dye-filling chemosensory mutants, is one of several proteins that have been classified as putatively involved in intraflagellar transport (IFT), the bidirectional movement of protein complexes along cilia and flagella, and specifically in anterograde IFT. Although genetic studies have highlighted a fundamental role of DYF-13 in nematode sensory cilium and trypanosome flagellum biogenesis, biochemical studies on DYF-13 have lag...

  19. 右美托咪定对不同年龄患者顺行性遗忘作用的影响%Effects of dexmedetomidine on the anterograde amnesia in patients with different ages

    Institute of Scientific and Technical Information of China (English)

    胡志超; 孔莉; 许鹏程; 李颖; 董晓辉

    2015-01-01

    Objective To study the effects of dexmedetomidine on the anterograde amnesia in patients with different ages.Methods One hundred and twenty ASAⅠ~Ⅱpatients, age from 18 years to 84 years, 73 cases of male and 47 cases of female , who were dministered spinal-epidural anesthesia combined with dexmedetomidine and performed operation on hypogastrium ( except for caesarean section ) .All patients were randomly divided into four groups:group A, group B, group C and group D.Dexmedetomidine(1μg/kg) was infused intravenously for 10 min and the maintenance dose was 0.2 μg・ kg-1・ h-1 .The anterograde amnesia degree of dexmedetomidine was as-sessed 24 h after the operation .Results There was no significant difference in the anterograde amnesia of dexmedeto -midine between group A and group B ( P>0.05 ) , while there were significant differences in group C and group D compared with both group A and group B ( P<0.05 ) .Conclusion Anterograde amnesia occurs after using dexme-detomidine in elderly patients and with aging , the anterograde amnesia becomes more severe .%目的:观察右美托咪定对不同年龄患者顺行性遗忘作用的影响。方法选择美国麻醉医师学会( ASA)Ⅰ~Ⅱ级、年龄18~84岁,在腰硬联合麻醉下复合右美托咪定行下腹部(剖宫产术除外)手术患者120例,其中男73例,女47例。根据患者年龄的不同分为四组:A组(23±4)岁, B组(36±3)岁, C组(65±3)岁,D组(75±5)岁。所有患者均给予右美托咪定负荷量1μg/kg,泵入10 min之后以0.2μg・ kg-1・ h-1剂量维持。术后24 h回访患者并评定右美托咪定的顺行性遗忘作用。结果 A组和B组右美托咪定顺行性遗忘作用无明显不同(P>0.05),而C组与D组较前两组右美托咪定顺行性遗忘作用比较明显(P<0.05),并随年龄的增大明显增加( P<0.05)。结论右美托咪定具有一定的顺行性遗忘作用,且对老年患者更为明显。

  20. Structural Basis for Induction of Peripheral Neuropathy by Microtubule-Targeting Cancer Drugs.

    Science.gov (United States)

    Smith, Jennifer A; Slusher, Barbara S; Wozniak, Krystyna M; Farah, Mohamed H; Smiyun, Gregoriy; Wilson, Leslie; Feinstein, Stuart; Jordan, Mary Ann

    2016-09-01

    Peripheral neuropathy is a serious, dose-limiting side effect of cancer treatment with microtubule-targeting drugs. Symptoms present in a "stocking-glove" distribution, with longest nerves affected most acutely, suggesting a length-dependent component to the toxicity. Axonal transport of ATP-producing mitochondria along neuronal microtubules from cell body to synapse is crucial to neuronal function. We compared the effects of the drugs paclitaxel and ixabepilone that bind along the lengths of microtubules and the drugs eribulin and vincristine that bind at microtubule ends, on mitochondrial trafficking in cultured human neuronal SK-N-SH cells and on axonal transport in mouse sciatic nerves. Antiproliferative concentrations of paclitaxel and ixabepilone significantly inhibited the anterograde transport velocity of mitochondria in neuronal cells, whereas eribulin and vincristine inhibited transport only at significantly higher concentrations. Confirming these observations, anterogradely transported amyloid precursor protein accumulated in ligated sciatic nerves of control and eribulin-treated mice, but not in paclitaxel-treated mice, indicating that paclitaxel inhibited anterograde axonal transport, whereas eribulin did not. Electron microscopy of sciatic nerves of paclitaxel-treated mice showed reduced organelle accumulation proximal to the ligation consistent with inhibition of anterograde (kinesin based) transport by paclitaxel. In contrast, none of the drugs significantly affected retrograde (dynein based) transport in neuronal cells or mouse nerves. Collectively, these results suggest that paclitaxel and ixabepilone, which bind along the lengths and stabilize microtubules, inhibit kinesin-based axonal transport, but not dynein-based transport, whereas the microtubule-destabilizing drugs, eribulin and vincristine, which bind preferentially to microtubule ends, have significantly less effect on all microtubule-based axonal transport. Cancer Res; 76(17); 5115-23.

  1. Trafifc lights for axon growth:proteoglycans and their neuronal receptors

    Institute of Scientific and Technical Information of China (English)

    Yingjie Shen

    2014-01-01

    Axon growth is a central event in the development and post-injury plasticity of the nervous system. Growing axons encounter a wide variety of environmental instructions. Much like trafifc lights in controlling the migrating axons, chondroitin sulfate proteoglycans (CSPGs) and hepa-ran sulfate proteoglycans (HSPGs) often lead to“stop”and“go”growth responses in the axons, respectively. Recently, the LAR family and NgR family molecules were identified as neuronal receptors for CSPGs and HSPGs. These discoveries provided molecular tools for further study of mechanisms underlying axon growth regulation. More importantly, the identiifcation of these proteoglycan receptors offered potential therapeutic targets for promoting post-injury axon re-generation.

  2. Coculture of elongated neuron axon with poly (D, L-lactide-co-glycolide) biomembrane in vitro

    Institute of Scientific and Technical Information of China (English)

    程飚; 陈峥嵘

    2004-01-01

    Objective: To elongate human nerve axon in culture and search for suitable support matrices for peripheral nervous system transplantation.Methods: Human embryo cortical neuronal cells,seeded on poly ( D, L-lactide-co-glycolide ) ( PLGA )membrane scaffolds, were elongated with a self-made neuro-axon extending device. The growth and morphological changes of neuron axons were observed to measure axolemmal permeability after elongation.Neurofilament protein was stained by immunohistochemical technique.Results: Human embryo neuron axon could be elongated and cultured on the PLGA membrane and retain their normal form and function.Conclusions: Three dimensional scaffolds with elongated neuron axon have the basic characteristics of artificial nerves, indicating a fundemental theory of nerve repair with elongated neuron axon.

  3. Disruption of Cnp1 uncouples oligodendroglial functions in axonal support and myelination.

    Science.gov (United States)

    Lappe-Siefke, Corinna; Goebbels, Sandra; Gravel, Michel; Nicksch, Eva; Lee, John; Braun, Peter E; Griffiths, Ian R; Nave, Klaus-Armin

    2003-03-01

    Myelination of axons by oligodendrocytes enables rapid impulse propagation in the central nervous system. But long-term interactions between axons and their myelin sheaths are poorly understood. Here we show that Cnp1, which encodes 2',3'-cyclic nucleotide phosphodiesterase in oligodendrocytes, is essential for axonal survival but not for myelin assembly. In the absence of glial cyclic nucleotide phosphodiesterase, mice developed axonal swellings and neurodegeneration throughout the brain, leading to hydrocephalus and premature death. But, in contrast to previously studied myelin mutants, the ultrastructure, periodicity and physical stability of myelin were not altered in these mice. Genetically, the chief function of glia in supporting axonal integrity can thus be completely uncoupled from its function in maintaining compact myelin. Oligodendrocyte dysfunction, such as that in multiple sclerosis lesions, may suffice to cause secondary axonal loss. PMID:12590258

  4. Intracellular transport proteins: classification, structure and function of kinesins

    Directory of Open Access Journals (Sweden)

    Agnieszka Chudy

    2011-09-01

    Full Text Available Correct cell functioning, division and morphogenesis rely on efficient intracellular transport. Apart from dyneins and myosins, kinesins are the main proteins responsible for intracellular movement. Kinesins are a large, diverse group of motor proteins, which based on phylogenetic similarity were classified into fourteen families. Among these families, due to the location of their motor domains, three groups have been characterized: N-, C- and M-kinesin. As molecular motors, kinesins transport various molecules and vesicles mainly towards the microtubule plus end (from the cell body participating in anterograde transport, although there are also kinesins involved in retrograde transport (C-kinesins. Kinesins are also involved in spindle formation, chromosome segregation, and spermatogenesis. Because of their great importance for the correct functioning of cells, mutations in kinesin coding genes may lead to such neurodegenerative diseases as dominant hereditary spastic paraplegia or Charcot-Marie-Tooth disease.

  5. X11/Mint Genes Control Polarized Localization of Axonal Membrane Proteins in Vivo

    OpenAIRE

    Garrett G Gross; Lone, G. Mohiddin; Leung, Lok Kwan; Hartenstein, Volker; Guo, Ming

    2013-01-01

    Mislocalization of axonal proteins can result in misassembly and/or miswiring of neural circuits, causing disease. To date, only a handful of genes that control polarized localization of axonal membrane proteins have been identified. Here we report that Drosophila X11/Mint proteins are required for targeting several proteins, including human amyloid precursor protein (APP) and Drosophila APP-like protein (APPL), to axonal membranes and for their exclusion from dendrites of the mushroom body i...

  6. Actin turnover is required to prevent axon retraction driven by endogenous actomyosin contractility

    OpenAIRE

    Gallo, Gianluca; Yee, Hal F.; Letourneau, Paul C.

    2002-01-01

    Growth cone motility and guidance depend on the dynamic reorganization of filamentous actin (F-actin). In the growth cone, F-actin undergoes turnover, which is the exchange of actin subunits from existing filaments. However, the function of F-actin turnover is not clear. We used jasplakinolide (jasp), a cell-permeable macrocyclic peptide that inhibits F-actin turnover, to study the role of F-actin turnover in axon extension. Treatment with jasp caused axon retraction, demonstrating that axon ...

  7. Directional specificity and patterning of sensory axons in trigeminal ganglion–whisker pad cocultures

    OpenAIRE

    Gunhan-Agar, Emine; Haeberle, Adam; Erzurumlu, Reha S.

    2000-01-01

    In the rodent trigeminal pathway, trigeminal axons invade the developing whisker pad from a caudal to rostral direction. We investigated directional specificity of embryonic day (E). 15 rat trigeminal axons within this peripheral target field using explant cocultures. E15 trigeminal axons readily grow into the same age whisker pad explants and form follicle-related patterns along a caudal to rostral direction. They also can grow into this target from its lateral aspects. In contrast, they are...

  8. Differential Effects of NGF and NT-3 on Embryonic Trigeminal Axon Growth Patterns

    OpenAIRE

    Ulupinar, Emel; Jacquin, Mark F.; Erzurumlu, Reha S.

    2000-01-01

    We examined the effects of neurotrophins nerve growth factor (NGF) and neurotrophin-3 (NT-3) on trigeminal axon growth patterns. Embryonic (E13–15) wholemount explants of the rat trigeminal pathway including the whisker pads, trigeminal ganglia, and brainstem were cultured in serum-free medium (SFM) or SFM supplemented with NGF or NT-3 for 3 days. Trigeminal axon growth patterns were analyzed with the use of lipophilic tracer DiI. In wholemount cultures grown in SFM, trigeminal axon projectio...

  9. RNA Sequence Reveals Mouse Retinal Transcriptome Changes Early after Axonal Injury

    OpenAIRE

    Yasuda, Masayuki; Tanaka, Yuji; Ryu, Morin; Tsuda, Satoru; Nakazawa, Toru

    2014-01-01

    Glaucoma is an ocular disease characterized by progressive retinal ganglion cell (RGC) death caused by axonal injury. However, the underlying mechanisms involved in RGC death remain unclear. In this study, we investigated changes in the transcriptome profile following axonal injury in mice (C57BL/6) with RNA sequencing (RNA-seq) technology. The experiment group underwent an optic nerve crush (ONC) procedure to induce axonal injury in the right eye, and the control group underwent a sham proce...

  10. Roles of NAD in Protection of Axon against Degeneration via SIRT1 Pathways.

    Science.gov (United States)

    Zhang, Jing; Guo, Wei-Hua; Qi, Xiao-Xia; Li, Gui-Bao; Hu, Yan-Lai; Wu, Qi; Ding, Zhao-Xi; Li, Hong-Yu; Hao, Jing; Sun, Jin-Hao

    2016-04-30

    Axonal degeneration is a common pathological change of neurogenical disease which often arises before the neuron death. But it had not found any effective method to protect axon from degeneration. In this study we intended to confirm the protective effect of nicotinamide adenine dinucleotide (NAD), investigate the optimal administration dosage and time of NAD, and identify the relationship between silence signal regulating factor 1 (SIRT1) and axonal degeneration. An axonal degeneration model was established using dorsal root ganglion (DRG) neurons injured by vincristine to observe the protective effects of NAD to the injured axons. In addition, the potential contribution of the SIRT1 in axonal degeneration was also investigated. Through the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, immunochemistry staining, axons counting and length measuring, transmission electron microscope (TEM) observation, we demonstrated that NAD played an important role in preventing axonal degeneration. Further study revealed that the expression of SIRT1 and phosphorylated Akt1 (p-Akt1) was up-regulated when NAD was added into the culturing medium. Taking together, our results demonstrated that NAD might delay the axonal degeneration through SIRT1/Akt1 pathways. PMID:27080463

  11. MicroRNA-210 promotes sensory axon regeneration of adult mice in vivo and in vitro.

    Science.gov (United States)

    Hu, Yi-Wen; Jiang, Jing-Jing; Yan-Gao; Wang, Rui-Ying; Tu, Guan-Jun

    2016-05-27

    Axon regeneration as a critical step in nerve repairing and remodeling after peripheral nerve injury relies on regulation of gene expression. MicroRNAs are emerging to be important epigenetic regulators of gene expression to control axon regeneration. Here we used a novel in vivo electroporation approach to transfect microRNA-210 (miR-210) or siRNAs to adult mice dorsal root ganglion (DRG) neurons, measured the axon length 3days after sciatic nerve crush or dissociated DRG cultures in vitro to detect the effect of miR-210 in sensory axon regeneration. Importantly, we found that miR-210 overexpression could promote sensory axon regeneration and inhibit apoptsosis by ephrin-A3 (EFNA3). In addition, inhibition of endogenous miR-210 in DRG neurons impaired axon regeneration in vitro and in vivo, the regulatory effect of miR-210 was mediated by increased expression of EFNA3 because downregulation of EFNA3 fully rescued axon regeneration. We thus demonstrate that miR-210 is a new physiological regulator of sensory axon regeneration, and EFNA3 may be the functional target of miR-210. We conclude that miR-210 may play an important role in sensory axon regeneration. PMID:27102143

  12. N-Propionylmannosamine stimulates axonal elongation in a murine model of sciatic nerve injury

    Institute of Scientific and Technical Information of China (English)

    Christian Witzel; Werner Reutter; G Bjrn Stark; Georgios Koulaxouzidis

    2015-01-01

    Increasing evidence indicates that sialic acid plays an important role during nerve regeneration. Sialic acids can be modiifed in vitro as well as in vivo using metabolic oligosaccharide engineering of the N-acyl side chain. N-Propionylmannosamine (ManNProp) increases neurite outgrowth and accelerates the reestablishment of functional synapses in vitro. We investigated the inlfuence of systemic ManNProp application using a speciifc in vivo mouse model. Using mice expressing axonal lfuorescent proteins, we quantiifed the extension of regenerating axons, the number of regenerating axons, the number of arborising axons and the number of branches per axon 5 days after injury. Sciatic nerves from non-expressing mice were grafted into those expressing yellow lfuorescent protein. We began a twice-daily intraperitoneal application of either peracetylated ManNProp (200 mg/kg) or saline solution 5 days before injury, and continued it until nerve harvest (5 days after transection). ManNProp signiifcantly increased the mean distance of axonal regeneration (2.49 mm vs. 1.53 mm;P<0.005) and the number of arborizing axons (21%vs. 16%;P=0.008) 5 days after sciatic nerve grafting. ManNProp did not affect the number of regenerating axons or the number of branches per arborizing axon. The biochemical glycoen-gineering of the N-acyl side chain of sialic acid might be a promising approach for improving peripheral nerve regeneration.

  13. N-Propionylmannosamine stimulates axonal elongation in a murine model of sciatic nerve injury

    Directory of Open Access Journals (Sweden)

    Christian Witzel

    2015-01-01

    Full Text Available Increasing evidence indicates that sialic acid plays an important role during nerve regeneration. Sialic acids can be modified in vitro as well as in vivo using metabolic oligosaccharide engineering of the N-acyl side chain. N-Propionylmannosamine (ManNProp increases neurite outgrowth and accelerates the reestablishment of functional synapses in vitro. We investigated the influence of systemic ManNProp application using a specific in vivo mouse model. Using mice expressing axonal fluorescent proteins, we quantified the extension of regenerating axons, the number of regenerating axons, the number of arborising axons and the number of branches per axon 5 days after injury. Sciatic nerves from non-expressing mice were grafted into those expressing yellow fluorescent protein. We began a twice-daily intraperitoneal application of either peracetylated ManNProp (200 mg/kg or saline solution 5 days before injury, and continued it until nerve harvest (5 days after transection. ManNProp significantly increased the mean distance of axonal regeneration (2.49 mm vs. 1.53 mm; P < 0.005 and the number of arborizing axons (21% vs. 16% P = 0.008 5 days after sciatic nerve grafting. ManNProp did not affect the number of regenerating axons or the number of branches per arborizing axon. The biochemical glycoengineering of the N-acyl side chain of sialic acid might be a promising approach for improving peripheral nerve regeneration.

  14. Regulation of axon guidance by compartmentalized nonsense-mediated mRNA decay

    DEFF Research Database (Denmark)

    Colak, Dilek; Ji, Sheng-Jian; Porse, Bo T; Jaffrey, Samie R

    2013-01-01

    show that Robo3.2, a receptor for the Slit family of guidance cues, is synthesized locally within axons of commissural neurons. Robo3.2 translation is induced by floor-plate-derived signals as axons cross the spinal cord midline. Robo3.2 is also a predicted target of the nonsense-mediated mRNA decay...... (NMD) pathway. We find that NMD regulates Robo3.2 synthesis by inducing the degradation of Robo3.2 transcripts in axons that encounter the floor plate. Commissural neurons deficient in NMD proteins exhibit aberrant axonal trajectories after crossing the midline, consistent with misregulation of Robo3...

  15. Permissive Schwann cell graft/spinal cord interfaces for axon regeneration.

    Science.gov (United States)

    Williams, Ryan R; Henao, Martha; Pearse, Damien D; Bunge, Mary Bartlett

    2015-01-01

    The transplantation of autologous Schwann cells (SCs) to repair the injured spinal cord is currently being evaluated in a clinical trial. In support, this study determined properties of spinal cord/SC bridge interfaces that enabled regenerated brainstem axons to cross them, possibly leading to improvement in rat hindlimb movement. Fluid bridges of SCs and Matrigel were placed in complete spinal cord transections. Compared to pregelled bridges of SCs and Matrigel, they improved regeneration of brainstem axons across the rostral interface. The regenerating brainstem axons formed synaptophysin(+) bouton-like terminals and contacted MAP2A(+) dendrites at the caudal interface. Brainstem axon regeneration was directly associated with glial fibrillary acidic protein (GFAP(+)) astrocyte processes that elongated into the SC bridge. Electron microscopy revealed that axons, SCs, and astrocytes were enclosed together within tunnels bounded by a continuous basal lamina. Neuroglycan (NG2) expression was associated with these tunnels. One week after injury, the GFAP(+) processes coexpressed nestin and brain lipid-binding protein, and the tips of GFAP(+)/NG2(+) processes extended into the bridges together with the regenerating brainstem axons. Both brainstem axon regeneration and number of GFAP(+) processes in the bridges correlated with improvement in hindlimb locomotion. Following SCI, astrocytes may enter a reactive state that prohibits axon regeneration. Elongation of astrocyte processes into SC bridges, however, and formation of NG2(+) tunnels enable brainstem axon regeneration and improvement in function. It is important for spinal cord repair to define conditions that favor elongation of astrocytes into lesions/transplants. PMID:24152553

  16. Studying Axonal Regeneration by Laser Microsurgery and High-Resolution Videomicroscopy.

    Science.gov (United States)

    Xiao, Yan; López-Schier, Hernán

    2016-01-01

    Heterogeneous and unpredictable environmental insult, disease, or trauma can affect the integrity and function of neuronal circuits, leading to irreversible neural dysfunction. The peripheral nervous system can robustly regenerate axons after damage to recover the capacity to transmit sensory information to the brain. The mechanisms that allow axonal repair remain incompletely understood. Here we present a preparation in zebrafish that combines laser microsurgery of sensory axons and videomicroscopy of neurons in multicolor transgenic specimens. This simple protocol allows controlled damage of axons and dynamic high-resolution visualization and quantification of repair. PMID:27464814

  17. Axons, but not cell bodies, are activated by electrical stimulation in cortical gray matter. II. Evidence from selective inactivation of cell bodies and axon initial segments.

    Science.gov (United States)

    Nowak, L G; Bullier, J

    1998-02-01

    The results presented in the companion paper showed that extracellular electrical stimulation of the gray matter directly activates axons, but not cell bodies. The second set of experiments presented here was designed to separate the contribution of the axon initial segments and cell bodies from that of the axonal branches to the pool of presynaptic neuronal elements activated by electrical stimulation. For that purpose, N-methyl-D-aspartate (NMDA) iontophoresis was used to induce a selective inactivation of the cell body and of the adjoining portion of the axon by depolarization block, without affecting axonal branches that lack NMDA receptors. After NMDA iontophoresis, the neurons located near the iontophoresis electrode became unable to generate action potentials in an irreversible manner. When the NMDA-induced depolarization block was performed at the site of electrical stimulation, an unexpected increase in the amplitude of the orthodromic responses was observed. Several control experiments suggested that the field potential increase was due to changes of the local environment in the vicinity of the iontophoresis pipette, which led to an increased excitability of the axons. After the period of superexcitability, the orthodromic responses displayed an amplitude that was 15-20% lower than that observed before the NMDA-induced depolarization block, even though cell bodies and axon initial segment at the site of stimulation could not be activated by electrical stimulation. This result shows a low contribution for axon initial segments to the pool of neuronal elements activated by the electrical stimulation. Altogether, these experiments demonstrate that the postsynaptic responses obtained after electrical stimulation of the cortical gray matter result almost exclusively from the activation of axonal branches. Since the neocortex is organised as a network of local and long-range reciprocal connections, great attention must be paid to the interpretation of data

  18. Biomarker evidence of axonal injury in neuroasymptomatic HIV-1 patients.

    Directory of Open Access Journals (Sweden)

    Jan Jessen Krut

    Full Text Available Prevalence of neurocognitive impairment in HIV-1 infected patients is reported to be high. Whether this is a result of active HIV-related neurodegeneration is unclear. We examined axonal injury in HIV-1 patients by measuring the light subunit of neurofilament protein (NFL in CSF with a novel, sensitive method.With a cross-sectional design, CSF concentrations of neurofilament protein light (NFL (marker of neuronal injury, neopterin (intrathecal immunoactivation and CSF/Plasma albumin ratio (blood-brain barrier integrity were analyzed on CSF from 252 HIV-infected patients, subdivided into untreated neuroasymptomatics (n = 200, HIV-associated dementia (HAD (n = 14 and on combinations antiretroviral treatment (cART (n = 85, and healthy controls (n = 204. 46 HIV-infected patients were included in both treated and untreated groups, but sampled at different timepoints. Furthermore, 78 neuroasymptomatic patients were analyzed before and after treatment initiation.While HAD patients had the highest NFL concentrations, elevated CSF NFL was also found in 33% of untreated neuroasymptomatic patients, mainly in those with blood CD4+ cell counts below 250 cells/μL. CSF NFL concentrations in the untreated neuroasymptomatics and treated groups were equivalent to controls 18.5 and 3.9 years older, respectively. Neopterin correlated with NFL levels in untreated groups while the albumin ratio correlated with NFL in both untreated and treated groups.Increased CSF NFL indicates ongoing axonal injury in many neuroasymptomatic patients. Treatment decreases NFL, but treated patients retain higher levels than controls, indicating either continued virus-related injury or an aging-like effect of HIV infection. NFL correlates with neopterin and albumin ratio, suggesting an association between axonal injury, neuroinflammation and blood-brain barrier permeability. NFL appears to be a sensitive biomarker of subclinical and clinical brain injury in HIV and warrants further

  19. Hyperactivated Stat3 boosts axon regeneration in the CNS.

    Science.gov (United States)

    Mehta, Saloni T; Luo, Xueting; Park, Kevin K; Bixby, John L; Lemmon, Vance P

    2016-06-01

    Axonal regeneration after spinal cord injury (SCI) is intrinsically and extrinsically inhibited by multiple factors. One major factor contributing to intrinsic regeneration failure is the inability of mature neurons in the central nervous system (CNS) to activate regeneration-associated transcription factors (TFs) post-injury. A prior study identified TFs overexpressed in neurons of the peripheral nervous system (PNS) compared to the CNS; some of these could be involved in the ability of PNS neurons to regenerate. Of these, signal transducer and activator of transcription 3 (STAT3), as well its downstream regeneration-associated targets, showed a significant upregulation in PNS neurons relative to CNS neurons, and a constitutively active variant of Stat3 (Stat3CA) promoted neurite growth when expressed in cerebellar neurons (Lerch et al., 2012; Smith et al., 2011). To further enhance STAT3's neurite outgrowth enhancing activity, Stat3CA was fused with a viral activation domain (VP16). VP16 hyperactivates TFs by recruiting transcriptional co-factors to the DNA binding domain (Hirai et al., 2010). Overexpression of this VP16-Stat3CA chimera in primary cortical neurons led to a significant increase of neurite outgrowth as well as Stat3 transcriptional activity in vitro. Furthermore, in vivo transduction of retinal ganglion cells (RGCs) with AAV constructs expressing VP16-Stat3CA resulted in regeneration of optic nerve axons after injury, to a greater degree than for those expressing Stat3CA alone. These findings confirm and extend the concept that overexpression of hyperactivated transcription factors identified as functioning in PNS regeneration can promote axon regeneration in the CNS. PMID:27060489

  20. Excitability properties of motor axons in adults with cerebral palsy

    Directory of Open Access Journals (Sweden)

    Cliff S. Klein

    2015-06-01

    Full Text Available Cerebral Palsy (CP is a permanent disorder caused by a lesion to the developing brain that significantly impairs motor function. The neurophysiological mechanisms underlying motor impairment are not well understood. Specifically, few have addressed whether motoneuron or peripheral axon properties are altered in CP, even though disruption of descending inputs to the spinal cord may cause them to change. In the present study, we have compared nerve excitability properties in seven adults with CP and fourteen healthy controls using threshold tracking techniques by stimulating the median nerve at the wrist and recording the compound muscle action potential (CMAP over the abductor pollicis brevis. The excitability properties in the CP subjects were found to be abnormal. Early and late depolarizing and hyperpolarizing threshold electrotonus was significantly larger (i.e., fanning out, and resting current-threshold (I/V slope was smaller, in CP compared to control. In addition resting threshold and rheobase tended to be larger in CP. According to a modeling analysis of the data, an increase in leakage current under or through the myelin sheath, i.e., the Barrett-Barrett conductance (GBB, combined with a slight hyperpolarization of the resting membrane potential, best explained the group differences in excitability properties. There was a trend for those with greater impairment in gross motor function to have more abnormal axon properties. The findings indicate plasticity of motor axon properties far removed from the site of the lesion. We suspect that this plasticity is caused by disruption of descending inputs to the motoneurons at an early age around the time of their injury.

  1. Mechanisms of hyperpolarization in regenerated mature motor axons in cat

    DEFF Research Database (Denmark)

    Moldovan, Mihai; Krarup, Christian

    2004-01-01

    We found persistent abnormalities in the recovery of membrane excitability in long-term regenerated motor nerve fibres in the cat as indicated in the companion paper. These abnormalities could partly be explained by membrane hyperpolarization. To further investigate this possibility, we compared...... the changes in excitability in control nerves and long-term regenerated cat nerves (3-5 years after tibial nerve crush) during manoeuvres known to alter axonal membrane Na(+)-K(+) pump function: polarization, cooling to 20 degrees C, reperfusion after 10 min ischaemia, and up to 60 s of repetitive stimulation...

  2. Matrix metalloproteinases as promising regulators of axonal regrowth in the injured adult zebrafish retinotectal system.

    Science.gov (United States)

    Lemmens, Kim; Bollaerts, Ilse; Bhumika, Stitipragyan; de Groef, Lies; Van Houcke, Jessie; Darras, Veerle M; Van Hove, Inge; Moons, Lieve

    2016-05-01

    Overcoming the failure of axon regeneration in the mammalian central nervous system (CNS) after injury remains a major challenge, which makes the search for proregenerative molecules essential. Matrix metalloproteinases (MMPs) have been implicated in axonal outgrowth during CNS development and show increased expression levels during vertebrate CNS repair. In mammals, MMPs are believed to alter the suppressive extracellular matrix to become more permissive for axon regrowth. We investigated the role of MMPs in axonal regeneration following optic nerve crush (ONC) in adult zebrafish, which fully recover from such injuries due to a high intrinsic axon growth capacity and a less inhibitory environment. Lowering general retinal MMP activity through intravitreal injections of GM6001 after ONC strongly reduced retinal ganglion cell (RGC) axonal regrowth, without influencing RGC survival. Based on a recently performed transcriptome profiling study, the expression pattern of four MMPs after ONC was determined via combined use of western blotting and immunostainings. Mmp-2 and -13a were increasingly present in RGC somata during axonal regrowth. Moreover, Mmp-2 and -9 became upregulated in regrowing RGC axons and inner plexiform layer (IPL) synapses, respectively. In contrast, after an initial rise in IPL neurites and RGC axons during the injury response, Mmp-14 expression decreased during regeneration. Altogether, a phase-dependent expression pattern for each specific MMP was observed, implicating them in axonal regrowth and inner retina remodeling after injury. In conclusion, these data suggest a novel, neuron-intrinsic function for multiple MMPs in axon regrowth that is distinct from breaking down environmental barriers. J. Comp. Neurol. 524:1472-1493, 2016. © 2015 Wiley Periodicals, Inc. PMID:26509469

  3. Gogo receptor contributes to retinotopic map formation and prevents R1-6 photoreceptor axon bundling.

    Directory of Open Access Journals (Sweden)

    Irina Hein

    Full Text Available BACKGROUND: Topographic maps form the basis of neural processing in sensory systems of both vertebrate and invertebrate species. In the Drosophila visual system, neighboring R1-R6 photoreceptor axons innervate adjacent positions in the first optic ganglion, the lamina, and thereby represent visual space as a continuous map in the brain. The mechanisms responsible for the establishment of retinotopic maps remain incompletely understood. RESULTS: Here, we show that the receptor Golden goal (Gogo is required for R axon lamina targeting and cartridge elongation in a partially redundant fashion with local guidance cues provided by neighboring axons. Loss of function of Gogo in large clones of R axons results in aberrant R1-R6 fascicle spacing. Gogo affects target cartridge selection only indirectly as a consequence of the disordered lamina map. Interestingly, small clones of gogo deficient R axons perfectly integrate into a proper retinotopic map suggesting that surrounding R axons of the same or neighboring fascicles provide complementary spatial guidance. Using single photoreceptor type rescue, we show that Gogo expression exclusively in R8 cells is sufficient to mediate targeting of all photoreceptor types in the lamina. Upon lamina targeting and cartridge selection, R axons elongate within their individual cartridges. Interestingly, here Gogo prevents bundling of extending R1-6 axons. CONCLUSION: Taken together, we propose that Gogo contributes to retinotopic map formation in the Drosophila lamina by controlling the distribution of R1-R6 axon fascicles. In a later developmental step, the regular position of R1-R6 axons along the lamina plexus is crucial for target cartridge selection. During cartridge elongation, Gogo allows R1-R6 axons to extend centrally in the lamina cartridge.

  4. An ex vivo laser-induced spinal cord injury model to assess mechanisms of axonal degeneration in real-time.

    Science.gov (United States)

    Okada, Starlyn L M; Stivers, Nicole S; Stys, Peter K; Stirling, David P

    2014-01-01

    Injured CNS axons fail to regenerate and often retract away from the injury site. Axons spared from the initial injury may later undergo secondary axonal degeneration. Lack of growth cone formation, regeneration, and loss of additional myelinated axonal projections within the spinal cord greatly limits neurological recovery following injury. To assess how central myelinated axons of the spinal cord respond to injury, we developed an ex vivo living spinal cord model utilizing transgenic mice that express yellow fluorescent protein in axons and a focal and highly reproducible laser-induced spinal cord injury to document the fate of axons and myelin (lipophilic fluorescent dye Nile Red) over time using two-photon excitation time-lapse microscopy. Dynamic processes such as acute axonal injury, axonal retraction, and myelin degeneration are best studied in real-time. However, the non-focal nature of contusion-based injuries and movement artifacts encountered during in vivo spinal cord imaging make differentiating primary and secondary axonal injury responses using high resolution microscopy challenging. The ex vivo spinal cord model described here mimics several aspects of clinically relevant contusion/compression-induced axonal pathologies including axonal swelling, spheroid formation, axonal transection, and peri-axonal swelling providing a useful model to study these dynamic processes in real-time. Major advantages of this model are excellent spatiotemporal resolution that allows differentiation between the primary insult that directly injures axons and secondary injury mechanisms; controlled infusion of reagents directly to the perfusate bathing the cord; precise alterations of the environmental milieu (e.g., calcium, sodium ions, known contributors to axonal injury, but near impossible to manipulate in vivo); and murine models also offer an advantage as they provide an opportunity to visualize and manipulate genetically identified cell populations and subcellular

  5. Bazooka mediates secondary axon morphology in Drosophila brain lineages

    Directory of Open Access Journals (Sweden)

    Hartenstein Volker

    2011-04-01

    Full Text Available Abstract In the Drosophila brain, neural lineages project bundled axon tracts into a central neuropile. Each lineage exhibits a stereotypical branching pattern and trajectory, which distinguish it from other lineages. In this study, we used a multilineage approach to explore the neural function of the Par-complex member Par3/Bazooka in vivo. Drosophila bazooka is expressed in post-mitotic neurons of the larval brain and localizes within neurons in a lineage-dependent manner. The fact that multiple GAL4 drivers have been mapped to several lineages of the Drosophila brain enables investigation of the role of Bazooka from larval to adult stages Bazooka loss-of-function (LOF clones had abnormal morphologies, including aberrant pathway choice of ventral projection neurons in the BAla1 lineage, ectopic branching in the DALv2 and BAmv1 lineages, and excess BLD5 lineage axon projections in the optic medulla. Exogenous expression of Bazooka protein in BAla1 neurons rescued defective guidance, supporting an intrinsic requirement for Bazooka in the post-mitotic neuron. Elimination of the Par-complex member Par6 recapitulated Bazooka phenotypes in some but not all lineages, suggesting that the Par complex functions in a lineage-dependent manner, and that Bazooka may act independently in some lineages. Importantly, this study highlights the potential of using a multilineage approach when studying gene function during neural development in Drosophila.

  6. Bazooka mediates secondary axon morphology in Drosophila brain lineages.

    Science.gov (United States)

    Spindler, Shana R; Hartenstein, Volker

    2011-01-01

    In the Drosophila brain, neural lineages project bundled axon tracts into a central neuropile. Each lineage exhibits a stereotypical branching pattern and trajectory, which distinguish it from other lineages. In this study, we used a multilineage approach to explore the neural function of the Par-complex member Par3/Bazooka in vivo. Drosophila bazooka is expressed in post-mitotic neurons of the larval brain and localizes within neurons in a lineage-dependent manner. The fact that multiple GAL4 drivers have been mapped to several lineages of the Drosophila brain enables investigation of the role of Bazooka from larval to adult stages Bazooka loss-of-function (LOF) clones had abnormal morphologies, including aberrant pathway choice of ventral projection neurons in the BAla1 lineage, ectopic branching in the DALv2 and BAmv1 lineages, and excess BLD5 lineage axon projections in the optic medulla. Exogenous expression of Bazooka protein in BAla1 neurons rescued defective guidance, supporting an intrinsic requirement for Bazooka in the post-mitotic neuron. Elimination of the Par-complex member Par6 recapitulated Bazooka phenotypes in some but not all lineages, suggesting that the Par complex functions in a lineage-dependent manner, and that Bazooka may act independently in some lineages. Importantly, this study highlights the potential of using a multilineage approach when studying gene function during neural development in Drosophila. PMID:21524279

  7. Bushen Yisui Capsule ameliorates axonal injury in experimental autoimmune encephalomyelitis

    Institute of Scientific and Technical Information of China (English)

    Ling Fang; Lei Wang; Qi Zheng; Tao Yang; Hui Zhao; Qiuxia Zhang; Kangning Li; Li Zhou; Haiyang Gong; Yongping Fan

    2013-01-01

    A preliminary clinical study by our group demonstrated Bushen Yisui Capsule (formerly cal ed Er-huang Formula) in combination with conventional therapy is an effective prescription for the treat-ment of multiple sclerosis. However, its effect on axonal injury during early multiple sclerosis re-mains unclear. In this study, a MOG 35-55-immunized C57BL/6 mouse model of experimental au-toimmune encephalomyelitis was intragastrical y administered Bushen Yisui Capsule. The results showed that Bushen Yisui Capsule effectively improved clinical symptoms and neurological function of experimental autoimmune encephalomyelitis. In addition, amyloid precursor protein expression was down-regulated and microtubule-associated protein 2 was up-regulated. Experimental findings indicate that the disease-preventive mechanism of Bushen Yisui Capsule in experimental autoim-mune encephalomyelitis was mediated by amelioration of axonal damage and promotion of rege-neration. But the effects of the high-dose Bushen Yisui Capsule group was not better than that of the medium-dose and low-dose Bushen Yisui Capsule group in preventing neurological dysfunction.

  8. N-docosahexaenoylethanolamine regulates Hedgehog signaling and promotes growth of cortical axons

    Directory of Open Access Journals (Sweden)

    Giorgi Kharebava

    2015-12-01

    Full Text Available Axonogenesis, a process for the establishment of neuron connectivity, is central to brain function. The role of metabolites derived from docosahexaenoic acid (DHA, 22:6n-3 that is specifically enriched in the brain, has not been addressed in axon development. In this study, we tested if synaptamide (N-docosahexaenoylethanolamine, an endogenous metabolite of DHA, affects axon growth in cultured cortical neurons. We found that synaptamide increased the average axon length, inhibited GLI family zinc finger 1 (GLI1 transcription and sonic hedgehog (Shh target gene expression while inducing cAMP elevation. Similar effects were produced by cyclopamine, a regulator of the Shh pathway. Conversely, Shh antagonized elevation of cAMP and blocked synaptamide-mediated increase in axon length. Activation of Shh pathway by a smoothened (SMO agonist (SAG or overexpression of SMO did not inhibit axon growth mediated by synaptamide or cyclopamine. Instead, adenylate cyclase inhibitor SQ22536 abolished synaptamide-mediated axon growth indicating requirement of cAMP elevation for this process. Our findings establish that synaptamide promotes axon growth while Shh antagonizes synaptamide-mediated cAMP elevation and axon growth by a SMO-independent, non-canonical pathway.

  9. Fast and simplified mapping of mean axon diameter using temporal diffusion spectroscopy.

    Science.gov (United States)

    Xu, Junzhon; Li, Hua; Li, Ke; Harkins, Kevin D; Jiang, Xiaoyu; Xie, Jingping; Kang, Hakmook; Dortch, Richard D; Anderson, Adam W; Does, Mark D

    2016-04-01

    Mapping axon diameter is of interest for the potential diagnosis and monitoring of various neuronal pathologies. Advanced diffusion-weighted MRI methods have been developed to measure mean axon diameters non-invasively, but suffer major drawbacks that prevent their direct translation into clinical practice, such as complex non-linear data fitting and, more importantly, long scanning times that are usually not tolerable for most human subjects. In the current study, temporal diffusion spectroscopy using oscillating diffusion gradients was used to measure mean axon diameters with high sensitivity to small axons in the central nervous system. Axon diameters have been found to be correlated with a novel metric, DDR⊥ (the rate of dispersion of the perpendicular diffusion coefficient with gradient frequency), which is a model-free quantity that does not require complex data analyses and can be obtained from two diffusion coefficient measurements in clinically relevant times with conventional MRI machines. A comprehensive investigation including computer simulations and animal experiments ex vivo showed that measurements of DDR⊥ agree closely with histological data. In humans in vivo, DDR⊥ was also found to correlate well with reported mean axon diameters in human corpus callosum, and the total scan time was only about 8 min. In conclusion, DDR⊥ may have potential to serve as a fast, simple and model-free approach to map the mean axon diameter of white matter in clinics for assessing axon diameter changes. PMID:27077155

  10. CD8+ T cells cause disability and axon loss in a mouse model of multiple sclerosis.

    Directory of Open Access Journals (Sweden)

    Chandra Deb

    Full Text Available BACKGROUND: The objective of this study was to test the hypothesis that CD8+ T cells directly mediate motor disability and axon injury in the demyelinated central nervous system. We have previously observed that genetic deletion of the CD8+ T cell effector molecule perforin leads to preservation of motor function and preservation of spinal axons in chronically demyelinated mice. METHODOLOGY/PRINCIPAL FINDINGS: To determine if CD8+ T cells are necessary and sufficient to directly injure demyelinated axons, we adoptively transferred purified perforin-competent CD8+ spinal cord-infiltrating T cells into profoundly demyelinated but functionally preserved perforin-deficient host mice. Transfer of CD8+ spinal cord-infiltrating T cells rapidly and irreversibly impaired motor function, disrupted spinal cord motor conduction, and reduced the number of medium- and large-caliber spinal axons. Likewise, immunodepletion of CD8+ T cells from chronically demyelinated wildtype mice preserved motor function and limited axon loss without altering other disease parameters. CONCLUSIONS/SIGNIFICANCE: In multiple sclerosis patients, CD8+ T cells outnumber CD4+ T cells in active lesions and the number of CD8+ T cells correlates with the extent of ongoing axon injury and functional disability. Our findings suggest that CD8+ T cells may directly injure demyelinated axons and are therefore a viable therapeutic target to protect axons and motor function in patients with multiple sclerosis.

  11. A model of fasciculation and sorting in mixed populations of axons

    CERN Document Server

    Chaudhuri, Debasish; Zapotocky, Martin

    2010-01-01

    We extend a recently proposed model (Chaudhuri et al., EPL 87, 20003 (2009)), aiming to describe the formation of fascicles of axons during neural development. The growing axons are represented as paths of interacting directed random walkers in two spatial dimensions. To mimic turnover of axons, whole paths are removed and new walkers are injected with specified rates. In the simplest version of the model, we use strongly adhesive inter-axon interactions that are identical for all pairs of axons. We generalize the model to interactions of finite strengths and to multiple types of axons with type-specific interactions. The dynamic steady state is characterized by the position-dependent distribution of fascicle sizes. With distance in the direction of axon growth, the mean fascicle size and emergent time scales grow monotonically, while the degree of sorting of fascicles by axon type has a maximum at a finite distance. To understand the emergence of slow time scales, we develop an analytical framework to analyz...

  12. Axonal plasticity elicits long-term changes in oligodendroglia and myelinated fibers

    DEFF Research Database (Denmark)

    Drøjdahl, Nina; Nielsen, Helle Hvilsted; Gardi, Jonathan E;

    2010-01-01

    Axons are linked to induction of myelination during development and to the maintenance of myelin and myelinated tracts in the adult CNS. Currently, it is unknown whether and how axonal plasticity in adult CNS impacts the myelinating cells and their precursors. In this article, we report that newl...

  13. Blast overpressure induced axonal injury changes in rat brainstem and spinal cord

    Directory of Open Access Journals (Sweden)

    Srinivasu Kallakuri

    2015-01-01

    Full Text Available Introduction: Blast induced neurotrauma has been the signature wound in returning soldiers from the ongoing wars in Iraq and Afghanistan. Of importance is understanding the pathomechansim(s of blast overpressure (OP induced axonal injury. Although several recent animal models of blast injury indicate the neuronal and axonal injury in various brain regions, animal studies related to axonal injury in the white matter (WM tracts of cervical spinal cord are limited. Objective: The purpose of this study was to assess the extent of axonal injury in WM tracts of cervical spinal cord in male Sprague Dawley rats subjected to a single insult of blast OP. Materials and Methods: Sagittal brainstem sections and horizontal cervical spinal cord sections from blast and sham animals were stained by neurofilament light (NF-L chain and beta amyloid precursor protein immunocytochemistry and observed for axonal injury changes. Results: Observations from this preliminary study demonstrate axonal injury changes in the form of prominent swellings, retraction bulbs, and putative signs of membrane disruptions in the brainstem and cervical spinal cord WM tracts of rats subjected to blast OP. Conclusions: Prominent axonal injury changes following the blast OP exposure in brainstem and cervical spinal WM tracts underscores the need for careful evaluation of blast induced injury changes and associated symptoms. NF-L immunocytochemistry can be considered as an additional tool to assess the blast OP induced axonal injury.

  14. Axon-somatic back-propagation in detailed models of spinal alpha motoneurons

    Directory of Open Access Journals (Sweden)

    Pietro eBalbi

    2015-02-01

    Full Text Available Antidromic action potentials following distal stimulation of motor axons occasionally fail to invade the soma of alpha motoneurons in spinal cord, due to their passing through regions of high non-uniformity.Morphologically detailed conductance-based models of cat spinal alpha motoneurons have been developed, with the aim to reproduce and clarify some aspects of the electrophysiological behavior of the antidromic axon-somatic spike propagation. Fourteen 3D morphologically detailed somata and dendrites of cat spinal alpha motoneurons have been imported from an open-access web-based database of neuronal morphologies, NeuroMorpho.org, and instantiated in neurocomputational models. An axon hillock, an axonal initial segment and a myelinated axon are added to each model.By sweeping the diameter of the axonal initial segment (AIS and the axon hillock, as well as the maximal conductances of sodium channels at the AIS and at the soma, the developed models are able to show the relationships between different geometric and electrophysiological configurations and the voltage attenuation of the antidromically travelling wave.In particular, a greater than usually admitted sodium conductance at AIS is necessary and sufficient to overcome the dramatic voltage attenuation occurring during antidromic spike propagation both at the myelinated axon-AIS and at the AIS-soma transitions.

  15. A developmental timing switch promotes axon outgrowth independent of known guidance receptors.

    Directory of Open Access Journals (Sweden)

    Katherine Olsson-Carter

    2010-08-01

    Full Text Available To form functional neuronal connections, axon outgrowth and guidance must be tightly regulated across space as well as time. While a number of genes and pathways have been shown to control spatial features of axon development, very little is known about the in vivo mechanisms that direct the timing of axon initiation and elongation. The Caenorhabditis elegans hermaphrodite specific motor neurons (HSNs extend a single axon ventrally and then anteriorly during the L4 larval stage. Here we show the lin-4 microRNA promotes HSN axon initiation after cell cycle withdrawal. Axons fail to form in lin-4 mutants, while they grow prematurely in lin-4-overexpressing animals. lin-4 is required to down-regulate two inhibitors of HSN differentiation--the transcriptional regulator LIN-14 and the "stemness" factor LIN-28--and it likely does so through a cell-autonomous mechanism. This developmental switch depends neither on the UNC-40/DCC and SAX-3/Robo receptors nor on the direction of axon growth, demonstrating that it acts independently of ventral guidance signals to control the timing of HSN axon elongation.

  16. C. elegans: a new model organism for studies of axon regeneration

    OpenAIRE

    Ghosh-Roy, Anindya; Chisholm, Andrew D.

    2010-01-01

    Axonal regeneration in C. elegans was first reported five years ago. Individual GFP-labeled axons can be severed using laser microsurgery and their regrowth followed in vivo. Several neuron types display robust regrowth after injury, including motor and sensory neurons. The small size and transparency of C. elegans make possible large-scale genetic and pharmacological screens for regeneration phenotypes.

  17. Inhibition of kinesin-5 improves regeneration of injured axons by a novel microtubule-based mechanism

    Institute of Scientific and Technical Information of China (English)

    Peter W. Baas; Andrew J. Matamoros

    2015-01-01

    Microtubules have been identiifed as a powerful target for augmenting regeneration of injured adult axons in the central nervous system. Drugs that stabilize microtubules have shown some promise, but there are concerns that abnormally stabilizing microtubules may have only limited beneifts for regeneration, while at the same time may be detrimental to the normal work that microtubules perform for the axon. Kinesin-5 (also called kif11 or Eg5), a molecular motor protein best known for its crucial role in mitosis, acts as a brake on microtubule movements by other motor proteins in the axon. Drugs that inhibit kinesin-5, originally developed to treat cancer, result in greater mobility of microtubules in the axon and an overall shift in the forces on the microtubule array. As a result, the axon grows faster, retracts less, and more readily enters environments that are inhibitory to axonal regeneration. Thus, drugs that inhibit kinesin-5 offer a novel microtubule-based means to boost axonal regeneration without the concerns that ac-company abnormal stabilization of the microtubule array. Even so, inhibiting kinesin-5 is not without its own caveats, such as potential problems with navigation of the regenerating axon to its target, as well as morphological effects on dendrites that could affect learning and memory if the drugs reach the brain.

  18. Stages in axon formation: observations of growth of Aplysia axons in culture using video-enhanced contrast-differential interference contrast microscopy

    OpenAIRE

    1986-01-01

    The regenerative growth in culture of the axons of two giant identified neurons from the central nervous system of Aplysia californica was observed using video-enhanced contrast-differential interference contrast microscopy. This technique allowed the visualization in living cells of the membranous organelles of the growth cone. Elongation of axonal branches always occurred through the same sequence of events: A flat organelle-free veil protruded from the front of the growth cone, gradually f...

  19. Shank3 is localized in axons and presynaptic specializations of developing hippocampal neurons and involved in the modulation of NMDA receptor levels at axon terminals.

    Science.gov (United States)

    Halbedl, Sonja; Schoen, Michael; Feiler, Marisa S; Boeckers, Tobias M; Schmeisser, Michael J

    2016-04-01

    Autism-related Shank1, Shank2, and Shank3 are major postsynaptic scaffold proteins of excitatory glutamatergic synapses. A few studies, however, have already indicated that within a neuron, the presence of Shank family members is not limited to the postsynaptic density. By separating axons from dendrites of developing hippocampal neurons in microfluidic chambers, we show that RNA of all three Shank family members is present within axons. Immunostaining confirms these findings as all three Shanks are indeed found within separated axons and further co-localize with well-known proteins of the presynaptic specialization in axon terminals. Therefore, Shank proteins might not only serve as postsynaptic scaffold proteins, but also play a crucial role during axonal outgrowth and presynaptic development and function. This is supported by our findings that shRNA-mediated knockdown of Shank3 results in up-regulation of the NMDA receptor subunit GluN1 in axon terminals. Taken together, our findings will have major implications for the future analysis of neuronal Shank biology in both health and disease. Shank1, Shank2, and Shank3 are major postsynaptic scaffold proteins of excitatory glutamatergic synapses strongly related to several neuropsychiatric disorders. However, a few studies have already implicated a functional role of the Shanks beyond the postsynaptic density (PSD). We here show that all three Shanks are localized in both axons and pre-synaptic specializiations of developing hippocampal neurons in culture. We further provide evidence that Shank3 is involved in the modulation of NMDA receptor levels at axon terminals. Taken together, our study will open up novel avenues for the future analysis of neuronal Shank biology in both health and disease. PMID:26725465

  20. Transfer of vesicles from Schwann cell to axon: a novel mechanism of communication in the peripheral nervous system

    Directory of Open Access Journals (Sweden)

    María Alejandra eLopez-Verrilli

    2012-06-01

    Full Text Available Schwann cells (SCs are the glial component of the peripheral nervous system, with essential roles during development and maintenance of axons, as well as during regenerative processes after nerve injury. SCs increase conduction velocities by myelinating axons, regulate synaptic activity at presynaptic nerve terminals and are a source of trophic factors to neurons. Thus, development and maintenance of peripheral nerves are crucially dependent on local signalling between SCs and axons. In addition to the classic mechanisms of intercellular signalling, the possibility of communication through secreted vesicles has been poorly explored to date. Interesting recent findings suggest the occurrence of lateral transfer mediated by vesicles from glial cells to axons that could have important roles in axonal growth and axonal regeneration. Here, we review the role of vesicular transfer from SCs to axons and propose the benefits of this means in supporting neuronal and axonal maintenance and regeneration after nerve damage.

  1. Disrupted axon-glia interactions at the paranode in myelinated nerves cause axonal degeneration and neuronal cell death in the aged Caspr mutant mouse shambling.

    Science.gov (United States)

    Takagishi, Yoshiko; Katanosaka, Kimiaki; Mizoguchi, Hiroyuki; Murata, Yoshiharu

    2016-07-01

    Emerging evidence suggests that axonal degeneration is a disease mechanism in various neurodegenerative diseases and that the paranodes at the nodes of Ranvier may be the initial site of pathogenesis. We investigated the pathophysiology of the disease process in the central and peripheral nervous systems of a Caspr mutant mouse, shambling (shm), which is affected by disrupted paranodal structures and impaired nerve conduction of myelinated nerves. The shm mice manifest a progressive neurological phenotype as mice age. We found extensive axonal degeneration and a loss of neurons in the central nervous system and peripheral nervous system in aged shm mice. Axonal alteration of myelinated nerves was defined by abnormal distribution and expression of neurofilaments and derangements in the status of phosphorylated and non/de-phosphorylated neurofilaments. Autophagy-related structures were also accumulated in degenerated axons and neurons. In conclusion, our results suggest that disrupted axon-glia interactions at the paranode cause the cytoskeletal alteration in myelinated axons leading to neuronal cell death, and the process involves detrimental autophagy and aging as factors that promote the pathogenesis. PMID:27255813

  2. Axone, an ethnic probiotic containing food, reduces age of sexual maturity and increases poultry production.

    Science.gov (United States)

    Singh, Bhoj Raj; Singh, R K

    2014-06-01

    Axone (Akhuni) is a homemade synbiotic (Nagamese fermented soybean product) served as side dish in North Eastern India. In this study, effects of Axone feeding on growth, weight gain, sexual maturity and egg production on Vanaraja birds (a strain of poultry bird developed at PDP Hyderabad for villages and backyard poultry) were evaluated. Axone incorporation in commercial poultry feed at the rate of 5% (W/W) significantly improved growth rate (weight gain) both in male (p 0.001) and female (p 0.05) chicks, reduced age by 13 days at first egg laying (p 0.01), increased egg production (p ≤ 0.001) and improved egg weight (p ≤ 0.01). Microbiological analysis of Axone sample revealed that the major bacteria in Axone samples were Bacillus coagulans, well known for their probiotic value. PMID:24801640

  3. RIPK1 mediates axonal degeneration by promoting inflammation and necroptosis in ALS.

    Science.gov (United States)

    Ito, Yasushi; Ofengeim, Dimitry; Najafov, Ayaz; Das, Sudeshna; Saberi, Shahram; Li, Ying; Hitomi, Junichi; Zhu, Hong; Chen, Hongbo; Mayo, Lior; Geng, Jiefei; Amin, Palak; DeWitt, Judy Park; Mookhtiar, Adnan Kasim; Florez, Marcus; Ouchida, Amanda Tomie; Fan, Jian-bing; Pasparakis, Manolis; Kelliher, Michelle A; Ravits, John; Yuan, Junying

    2016-08-01

    Mutations in the optineurin (OPTN) gene have been implicated in both familial and sporadic amyotrophic lateral sclerosis (ALS). However, the role of this protein in the central nervous system (CNS) and how it may contribute to ALS pathology are unclear. Here, we found that optineurin actively suppressed receptor-interacting kinase 1 (RIPK1)-dependent signaling by regulating its turnover. Loss of OPTN led to progressive dysmyelination and axonal degeneration through engagement of necroptotic machinery in the CNS, including RIPK1, RIPK3, and mixed lineage kinase domain-like protein (MLKL). Furthermore, RIPK1- and RIPK3-mediated axonal pathology was commonly observed in SOD1(G93A) transgenic mice and pathological samples from human ALS patients. Thus, RIPK1 and RIPK3 play a critical role in mediating progressive axonal degeneration. Furthermore, inhibiting RIPK1 kinase may provide an axonal protective strategy for the treatment of ALS and other human degenerative diseases characterized by axonal degeneration. PMID:27493188

  4. The Drosophila immunoglobulin gene turtle encodes guidance molecules involved in axon pathfinding

    Directory of Open Access Journals (Sweden)

    Al-Anzi Bader

    2009-08-01

    Full Text Available Abstract Background Neuronal growth cones follow specific pathways over long distances in order to reach their appropriate targets. Research over the past 15 years has yielded a large body of information concerning the molecules that regulate this process. Some of these molecules, such as the evolutionarily conserved netrin and slit proteins, are expressed in the embryonic midline, an area of extreme importance for early axon pathfinding decisions. A general model has emerged in which netrin attracts commissural axons towards the midline while slit forces them out. However, a large number of commissural axons successfully cross the midline even in the complete absence of netrin signaling, indicating the presence of a yet unidentified midline attractant. Results The evolutionarily conserved Ig proteins encoded by the turtle/Dasm1 genes are found in Drosophila, Caenorhabditis elegans, and mammals. In Drosophila the turtle gene encodes five proteins, two of which are diffusible, that are expressed in many areas, including the vicinity of the midline. Using both molecular null alleles and transgenic expression of the different isoforms, we show that the turtle encoded proteins function as non-cell autonomous axonal attractants that promote midline crossing via a netrin-independent mechanism. turtle mutants also have either stalled or missing axon projections, while overexpression of the different turtle isoforms produces invasive neurons and branching axons that do not respect the histological divisions of the nervous system. Conclusion Our findings indicate that the turtle proteins function as axon guidance cues that promote midline attraction, axon branching, and axonal invasiveness. The latter two capabilities are required by migrating axons to explore densely packed targets.

  5. Excitation by Axon Terminal GABA Spillover in a Sound Localization Circuit.

    Science.gov (United States)

    Weisz, Catherine J C; Rubio, Maria E; Givens, Richard S; Kandler, Karl

    2016-01-20

    Synapses from neurons of the medial nucleus of the trapezoid body (MNTB) onto neurons of the lateral superior olive (LSO) in the auditory brainstem are glycinergic in maturity, but also GABAergic and glutamatergic in development. The role for this neurotransmitter cotransmission is poorly understood. Here we use electrophysiological recordings in brainstem slices from P3-P21 mice to demonstrate that GABA release evoked from MNTB axons can spill over to neighboring MNTB axons and cause excitation by activating GABAAR. This spillover excitation generates patterns of staggered neurotransmitter release from different MNTB axons resulting in characteristic "doublet" postsynaptic currents in LSO neurons. Postembedding immunogold labeling and electron microscopy provide evidence that GABAARs are localized at MNTB axon terminals. Photolytic uncaging of p-hydroxyphenacyl (pHP) GABA demonstrates backpropagation of GABAAR-mediated depolarizations from MNTB axon terminals to the soma, some hundreds of microns away. These somatic depolarizations enhanced somatic excitability by increasing the probability of action potential generation. GABA spillover excitation between MNTB axon terminals may entrain neighboring MNTB neurons, which may play a role in the developmental refinement of the MNTB-LSO pathway. Axonal spillover excitation persisted beyond the second postnatal week, suggesting that this mechanism may play a role in sound localization, by providing new avenues of communication between MNTB neurons via their distal axonal projections. Significance statement: In this study, a new mechanism of neuronal communication between auditory synapses in the mammalian sound localization pathway is described. Evidence is provided that the inhibitory neurotransmitter GABA can spill over between axon terminals to cause excitation of nearby synapses to further stimulate neurotransmitter release. Excitatory GABA spillover between inhibitory axon terminals may have important implications

  6. Dihydrotestosterone ameliorates degeneration in muscle, axons and motoneurons and improves motor function in amyotrophic lateral sclerosis model mice.

    Directory of Open Access Journals (Sweden)

    Young-Eun Yoo

    Full Text Available Amyotrophic lateral sclerosis (ALS is a lethal disease characterized by a progressive loss of motoneurons. The clinical symptoms include skeletal muscle weakness and atrophy, which impairs motor performance and eventually leads to respiratory failure. We tested whether dihydrotestosterone (DHT, which has both anabolic effects on muscle and neuroprotective effects on axons and motoneurons, can ameliorate clinical symptoms in ALS. A silastic tube containing DHT crystals was implanted subcutaneously in SOD1-G93A mice at early symptomatic age when decreases in body weight and grip-strength were observed as compared to wild-type mice. DHT-treated SOD1-G93A mice demonstrated ameliorated muscle atrophy and increased body weight, which was associated with stronger grip-strength. DHT treatment increased the expression of insulin-like growth factor-1 in muscle, which can exert myotrophic as well as neurotrophic effects through retrograde transport. DHT treatment attenuated neuromuscular junction denervation, and axonal and motoneuron loss. DHT-treated SOD1-G93A mice demonstrated improvement in motor behavior as assessed by rota-rod and gait analyses, and an increased lifespan. Application of DHT is a relatively simple and non-invasive procedure, which may be translated into therapy to improve the quality of life for ALS patients.

  7. Targeted axonal import (TAxI) peptide delivers functional proteins into spinal cord motor neurons after peripheral administration.

    Science.gov (United States)

    Sellers, Drew L; Bergen, Jamie M; Johnson, Russell N; Back, Heidi; Ravits, John M; Horner, Philip J; Pun, Suzie H

    2016-03-01

    A significant unmet need in treating neurodegenerative disease is effective methods for delivery of biologic drugs, such as peptides, proteins, or nucleic acids into the central nervous system (CNS). To date, there are no operative technologies for the delivery of macromolecular drugs to the CNS via peripheral administration routes. Using an in vivo phage-display screen, we identify a peptide, targeted axonal import (TAxI), that enriched recombinant bacteriophage accumulation and delivered protein cargo into spinal cord motor neurons after intramuscular injection. In animals with transected peripheral nerve roots, TAxI delivery into motor neurons after peripheral administration was inhibited, suggesting a retrograde axonal transport mechanism for delivery into the CNS. Notably, TAxI-Cre recombinase fusion proteins induced selective recombination and tdTomato-reporter expression in motor neurons after intramuscular injections. Furthermore, TAxI peptide was shown to label motor neurons in the human tissue. The demonstration of a nonviral-mediated delivery of functional proteins into the spinal cord establishes the clinical potential of this technology for minimally invasive administration of CNS-targeted therapeutics. PMID:26888285

  8. Dynamic Changes in Local Protein Synthetic Machinery in Regenerating Central Nervous System Axons after Spinal Cord Injury

    Science.gov (United States)

    Sachdeva, Rahul; Farrell, Kaitlin; McMullen, Mary-Katharine; Twiss, Jeffery L.; Houle, John D.

    2016-01-01

    Intra-axonal localization of mRNAs and protein synthesis machinery (PSM) endows neurons with the capacity to generate proteins locally, allowing precise spatiotemporal regulation of the axonal response to extracellular stimuli. A number of studies suggest that this local translation is a promising target to enhance the regenerative capacity of damaged axons. Using a model of central nervous system (CNS) axons regenerating into intraspinal peripheral nerve grafts (PNGs) we established that adult regenerating CNS axons contain several different mRNAs and protein synthetic machinery (PSM) components in vivo. After lower thoracic level spinal cord transection, ascending sensory axons regenerate into intraspinal PNGs but axon growth is stalled when they reach the distal end of the PNG (3 versus 7 weeks after grafting, resp.). By immunofluorescence with optical sectioning of axons by confocal microscopy, the total and phosphorylated forms of PSMs are significantly lower in stalled compared with actively regenerating axons. Reinjury of these stalled axons increased axonal localization of the PSM proteins, indicative of possible priming for a subcellular response to axotomy. These results suggest that axons downregulate protein synthetic capacity as they cease growing, yet they retain the ability to upregulate PSM after a second injury.

  9. The cholinergic ligand binding material of axonal membranes

    International Nuclear Information System (INIS)

    Choline acetyltransferase and acetylcholinesterase, the enzymes responsible for the synthesis and hydrolysis of ACh, are present in nerve fibers. In crustacean peripheral nerves, release of ACh from cut nerve fibers has been demonstrated. Previously closed membrane vesicles have been prepared from lobster walking leg nerve plasma membrane and saturable binding of cholinergic agonsist and antagonists to such membranes have been demonstrated. This paper studies this axonal cholinergic binding material, and elucidates its functions. The binding of tritium-nicotine to lobster nerve plasma membranes was antagonized by a series of cholinergic ligands as well as by a series of local anesthetics. This preparation was capable of binding I 125-alpha-bungarotoxin, a ligand widely believed to be a specific label for nicotinic ACh receptor. The labelling of 50 K petide band with tritium-MBTA following disulfide reduction is illustrated

  10. Diffuse axonal injury at ultra-high field MRI.

    Directory of Open Access Journals (Sweden)

    Christoph Moenninghoff

    Full Text Available Diffuse axonal injury (DAI is a specific type of traumatic brain injury caused by shearing forces leading to widespread tearing of axons and small vessels. Traumatic microbleeds (TMBs are regarded as a radiological marker for DAI. This study aims to compare DAI-associated TMBs at 3 Tesla (T and 7 T susceptibility weighted imaging (SWI to evaluate possible diagnostic benefits of ultra-high field (UHF MRI.10 study participants (4 male, 6 female, age range 20-74 years with known DAI were included. All MR exams were performed with a 3 T MR system (Magnetom Skyra and a 7 T MR research system (Magnetom 7 T, Siemens AG, Healthcare Sector, Erlangen, Germany each in combination with a 32-channel-receive coil. The average time interval between trauma and imaging was 22 months. Location and count of TMBs were independently evaluated by two neuroradiologists on 3 T and 7 T SWI images with similar and additionally increased spatial resolution at 7 T. Inter- and intraobserver reliability was assessed using the interclass correlation coefficient (ICC. Count and diameter of TMB were evaluated with Wilcoxon signed rank test.Susceptibility weighted imaging revealed a total of 485 TMBs (range 1-190, median 25 at 3 T, 584 TMBs (plus 20%, range 1-262, median 30.5 at 7 T with similar spatial resolution, and 684 TMBs (plus 41%, range 1-288, median 39.5 at 7 T with 10-times higher spatial resolution. Hemorrhagic DAI appeared significantly larger at 7 T compared to 3 T (p = 0.005. Inter- and intraobserver correlation regarding the counted TMB was high and almost equal 3 T and 7 T.7 T SWI improves the depiction of small hemorrhagic DAI compared to 3 T and may be supplementary to lower field strengths for diagnostic in inconclusive or medicolegal cases.

  11. Hindsight regulates photoreceptor axon targeting through transcriptional control of jitterbug/Filamin and multiple genes involved in axon guidance in Drosophila.

    Science.gov (United States)

    Oliva, Carlos; Molina-Fernandez, Claudia; Maureira, Miguel; Candia, Noemi; López, Estefanía; Hassan, Bassem; Aerts, Stein; Cánovas, José; Olguín, Patricio; Sierralta, Jimena

    2015-09-01

    During axon targeting, a stereotyped pattern of connectivity is achieved by the integration of intrinsic genetic programs and the response to extrinsic long and short-range directional cues. How this coordination occurs is the subject of intense study. Transcription factors play a central role due to their ability to regulate the expression of multiple genes required to sense and respond to these cues during development. Here we show that the transcription factor HNT regulates layer-specific photoreceptor axon targeting in Drosophila through transcriptional control of jbug/Filamin and multiple genes involved in axon guidance and cytoskeleton organization.Using a microarray analysis we identified 235 genes whose expression levels were changed by HNT overexpression in the eye primordia. We analyzed nine candidate genes involved in cytoskeleton regulation and axon guidance, six of which displayed significantly altered gene expression levels in hnt mutant retinas. Functional analysis confirmed the role of OTK/PTK7 in photoreceptor axon targeting and uncovered Tiggrin, an integrin ligand, and Jbug/Filamin, a conserved actin- binding protein, as new factors that participate of photoreceptor axon targeting. Moreover, we provided in silico and molecular evidence that supports jbug/Filamin as a direct transcriptional target of HNT and that HNT acts partially through Jbug/Filamin in vivo to regulate axon guidance. Our work broadens the understanding of how HNT regulates the coordinated expression of a group of genes to achieve the correct connectivity pattern in the Drosophila visual system. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 75: 1018-1032, 2015. PMID:25652545

  12. Assessing the axonal translocation of CeO2 and SiO2 nanoparticles in the sciatic nerve fibers of the frog: an ex vivo electrophysiological study.

    Science.gov (United States)

    Kastrinaki, Georgia; Samsouris, Christos; Kosmidis, Efstratios K; Papaioannou, Eleni; Konstandopoulos, Athanasios G; Theophilidis, George

    2015-01-01

    The axonal translocation of two commonly used nanoparticles in medicine, namely CeO2 and SiO2, is investigated. The study was conducted on frog sciatic nerve fibers in an ex vivo preparation. Nanoparticles were applied at the proximal end of the excised nerve. A nerve stimulation protocol was followed for over 35 hours. Nerve vitality curve comparison between control and exposed nerves showed that CeO2 has no neurotoxic effect at the concentrations tested. After exposure, specimens were fixed and then screen scanned every 1 mm along their length for nanoparticle presence by means of Fourier transform infrared microscopy. We demonstrated that both nanoparticles translocate within the nerve by formation of narrow bands in the Fourier transform infrared spectrum. For the CeO2, we also demonstrated that the translocation depends on both axonal integrity and electrical activity. The speed of translocation for the two species was estimated in the range of 0.45-0.58 mm/h, close to slow axonal transportation rate. Transmission electron microscopy provided direct evidence for the presence of SiO2 in the treated nerves. PMID:26648718

  13. Coordinated Eph-ephrin signaling guides migration and axon targeting in the avian auditory system

    Directory of Open Access Journals (Sweden)

    Allen-Sharpley Michelle R

    2012-08-01

    Full Text Available Abstract Background In the avian sound localization circuit, nucleus magnocellularis (NM projects bilaterally to nucleus laminaris (NL, with ipsilateral and contralateral NM axon branches directed to dorsal and ventral NL dendrites, respectively. We previously showed that the Eph receptor EphB2 is expressed in NL neuropil and NM axons during development. Here we tested whether EphB2 contributes to NM-NL circuit formation. Results We found that misexpression of EphB2 in embryonic NM precursors significantly increased the number of axon targeting errors from NM to contralateral NL in a cell-autonomous manner when forward signaling was impaired. We also tested the effects of inhibiting forward signaling of different Eph receptor subclasses by injecting soluble unclustered Fc-fusion proteins at stages when NM axons are approaching their NL target. Again we found an increase in axon targeting errors compared to controls when forward signaling was impaired, an effect that was significantly increased when both Eph receptor subclasses were inhibited together. In addition to axon targeting errors, we also observed morphological abnormalities of the auditory nuclei when EphB2 forward signaling was increased by E2 transfection, and when Eph-ephrin forward signaling was inhibited by E6-E8 injection of Eph receptor fusion proteins. Conclusions These data suggest that EphB signaling has distinct functions in axon guidance and morphogenesis. The results provide evidence that multiple Eph receptors work synergistically in the formation of precise auditory circuitry.

  14. Chemokines induce axon outgrowth downstream of Hepatocyte Growth Factor and TCF/β-catenin signaling

    Directory of Open Access Journals (Sweden)

    Judith Camats

    2013-04-01

    Full Text Available Axon morphogenesis is a complex process regulated by a variety of secreted molecules, including morphogens and growth factors, resulting in the establishment of the neuronal circuitry. Our previous work demonstrated that growth factors (Neurotrophins (NT and Hepatocyte Growth Factor (HGF signal through β-catenin during axon morphogenesis. HGF signaling promotes axon outgrowth and branching by inducing β-catenin phosphorylation at Y142 and transcriptional regulation of T-Cell Factor (TCF target genes. Here we asked which genes are regulated by HGF signaling during axon morphogenesis. An array screening indicated that HGF signaling elevates the expression of chemokines of the CC and CXC families. In line with this, CCL7, CCL20 and CXCL2 significantly increase axon outgrowth in hippocampal neurons. Experiments using blocking antibodies and chemokine receptor antagonists demonstrate that chemokines act downstream of HGF signaling during axon morphogenesis. In addition, qPCR data demonstrates that CXCL2 and CCL5 expression is stimulated by HGF through Met/b-catenin/TCF pathway. These results identify CC family members and CXCL2 chemokines as novel regulators of axon morphogenesis downstream of HGF signaling.

  15. Differential expression of axon-sorting molecules in mouse olfactory sensory neurons.

    Science.gov (United States)

    Ihara, Naoki; Nakashima, Ai; Hoshina, Naosuke; Ikegaya, Yuji; Takeuchi, Haruki

    2016-08-01

    In the mouse olfactory system, the axons of olfactory sensory neurons that express the same type of odorant receptor (OR) converge to a specific set of glomeruli in the olfactory bulb (OB). It is widely accepted that expressed OR molecules instruct glomerular segregation by regulating the expression of axon-sorting molecules. Although the relationship between the expression of axon-sorting molecules and OR types has been analyzed in detail, those between the expressions of axon-sorting molecules remain to be elucidated. Here we collected the expression profiles of four axon-sorting molecules from a large number of glomeruli in the OB. These molecules demonstrated position-independent mosaic expressions, but their patterns were not identical in the OB. Comparing their expressions identified positive and negative correlations between several pairs of genes even though they showed various expressions. Furthermore, the principal component analysis revealed that the factor loadings in the principal component 1, which explain the largest amount of variation, were most likely to reflect the degree of the cyclic nucleotide-gated (CNG) channel dependence on the expression of axon-sorting molecules. Thus, neural activity generated through the CNG channel is a major component in the generation of a wide variety of expressions of axon-sorting molecules in glomerular segregation. PMID:27207328

  16. Exosomes mediate cell contact-independent ephrin-Eph signaling during axon guidance.

    Science.gov (United States)

    Gong, Jingyi; Körner, Roman; Gaitanos, Louise; Klein, Rüdiger

    2016-07-01

    The cellular release of membranous vesicles known as extracellular vesicles (EVs) or exosomes represents a novel mode of intercellular communication. Eph receptor tyrosine kinases and their membrane-tethered ephrin ligands have very important roles in such biologically diverse processes as neuronal development, plasticity, and pathological diseases. Until now, it was thought that ephrin-Eph signaling requires direct cell contact. Although the biological functions of ephrin-Eph signaling are well understood, our mechanistic understanding remains modest. Here we report the release of EVs containing Ephs and ephrins by different cell types, a process requiring endosomal sorting complex required for transport (ESCRT) activity and regulated by neuronal activity. Treatment of cells with purified EphB2(+) EVs induces ephrinB1 reverse signaling and causes neuronal axon repulsion. These results indicate a novel mechanism of ephrin-Eph signaling independent of direct cell contact and proteolytic cleavage and suggest the participation of EphB2(+) EVs in neural development and synapse physiology. PMID:27354374

  17. gamma-Diketone neuropathy: axon atrophy and the role of cytoskeletal protein adduction.

    Science.gov (United States)

    LoPachin, Richard M; DeCaprio, Anthony P

    2004-08-15

    Multifocal giant neurofilamentous axonal swellings and secondary distal degeneration have been historically considered the hallmark features of gamma-diketone neuropathy. Accordingly, research conducted over the past 25 years has been directed toward discerning mechanisms of axonal swelling. However, this neuropathological convention has been challenged by recent observations that swollen axons were an exclusive product of long-term 2.5-hexanedione (HD) intoxication at lower daily dose-rates (e.g., 175 mg/kg/day); that is, higher HD dose-rates (e.g., 400 mg/kg/day) produced neurological deficits in the absence of axonal swellings. The observation that neurological toxicity can be expressed without axonal swelling suggests that this lesion is not an important pathophysiological event. Instead, several research groups have now shown that axon atrophy is prevalent in nervous tissues of laboratory animals intoxicated over a wide range of HD dose-rates. The well-documented nerve conduction defects associated with axon atrophy, in conjunction with the temporal correspondence between this lesion and the onset of neurological deficits, strongly suggest that atrophy has pathophysiological significance. In this commentary, we present evidence that supports a pathognomonic role for axon atrophy in gamma-diketone neuropathy and suggests that the functional consequences of this lesion mediate the corresponding neurological toxicity. Previous research has demonstrated that HD interacts with proteins via formation of pyrrole adducts. We therefore discuss the possibility that this chemical process is essential to the mechanism of atrophy. Evidence presented in this review suggests that "distal axonopathy" is an inaccurate classification and future nosological schemes should be based on the apparent primacy of axon atrophy. PMID:15289087

  18. Extracellular matrix molecules play diverse roles in the growth and guidance of central nervous system axons

    Directory of Open Access Journals (Sweden)

    M.A. Pires-Neto

    1999-05-01

    Full Text Available Axon growth and guidance represent complex biological processes in which probably intervene diverse sets of molecular cues that allow for the appropriate wiring of the central nervous system (CNS. The extracellular matrix (ECM represents a major contributor of molecular signals either diffusible or membrane-bound that may regulate different stages of neural development. Some of the brain ECM molecules form tridimensional structures (tunnels and boundaries that appear during time- and space-regulated events, possibly playing relevant roles in the control of axon elongation and pathfinding. This short review focuses mainly on the recognized roles played by proteoglycans, laminin, fibronectin and tenascin in axonal development during ontogenesis.

  19. Clinical features and molecular modelling of novel MPZ mutations in demyelinating and axonal neuropathies

    OpenAIRE

    Mandich, Paola; Fossa, Paola; Capponi, Simona; Geroldi, Alessandro; Acquaviva, Massimo; Gulli, Rossella; Ciotti, Paola; MANGANELLI, FIORE; Grandis, Marina; Bellone, Emilia

    2009-01-01

    Mutations in the myelin protein zero (MPZ) gene have been associated with different Charcot–Marie–Tooth disease (CMT) phenotypes, including classical demyelinating CMT1B and the axonal form of the disease (CMT2). The MPZ role in the pathogenesis of both demyelinating and axonal inherited neuropathies was evaluated in the Italian population by screening a cohort of 214 patients with CMT1 or CMT2. A MPZ mutation frequency of 7.9% in demyelinating cases and of 4.8% in axonal cases was observed. ...

  20. [A case of acute motor sensory axonal polyneuropathy after Haemophilus influenzae infection].

    Science.gov (United States)

    Oda, M; Udaka, F; Kubori, T; Oka, N; Kameyama, M

    2000-08-01

    A 47-year-old woman developed consciousness disturbance, and experienced hallucinations while traveling abroad, and then went into critical condition. She was placed in the critical care unit, and had flaccid tetraparesis requiring mechanical ventilation. Haemophilus influenzae was cultured from the sputum. The level of protein of the cerebrospinal fluid was elevated to 114 mg/dl, nerve conduction study showed findings of pure axonal damage, and the sural nerve biopsy revealed severe axonal degeneration. She improved gradually by plasma exchange. The diagnosis of acute motor sensory axonal polyneuropathy (AMSAN) based on autoimmune mechanism was made. We speculate that H. influenzae infection may have elicited AMSAN in this case. PMID:11218707

  1. Diffuse axonal injury: detection of changes in anisotropy of water diffusion by diffusion-weighted imaging

    Energy Technology Data Exchange (ETDEWEB)

    Chan, J.H.M.; Tsui, E.Y.K.; Yuen, M.K. [Department of Diagnostic Radiology, Tuen Mun Hospital, Tsing Chung Koon Road, Tuen Mun, N.T., Hong Kong (China); Peh, W.C.G. [Department of Diagnostic Radiology, Singapore General Hospital (Singapore); Fong, D.; Fok, K.F.; Leung, K.M. [Department of Neurosurgery, Tuen Mun Hospital (Hong Kong); Fung, K.K.L. [Department of Optometry and Radiography, Hong Kong Polytechnic University (China)

    2003-01-01

    Myelinated axons of white matter demonstrate prominent directional differences in water diffusion. We performed diffusion-weighted imaging on ten patients with head injury to explore the feasibility of using water diffusion anisotropy for quantitating diffuse axonal injury. We showed significant decrease in diffusion anisotropy indices in areas with or without signal abnormality on T2 and T2*-weighted images. We conclude that the water diffusion anisotropy index a potentially useful, sensitive and quantitative way of diagnosing and assessing patients with diffuse axonal injury. (orig.)

  2. Diffuse axonal injury: detection of changes in anisotropy of water diffusion by diffusion-weighted imaging

    International Nuclear Information System (INIS)

    Myelinated axons of white matter demonstrate prominent directional differences in water diffusion. We performed diffusion-weighted imaging on ten patients with head injury to explore the feasibility of using water diffusion anisotropy for quantitating diffuse axonal injury. We showed significant decrease in diffusion anisotropy indices in areas with or without signal abnormality on T2 and T2*-weighted images. We conclude that the water diffusion anisotropy index a potentially useful, sensitive and quantitative way of diagnosing and assessing patients with diffuse axonal injury. (orig.)

  3. Enzyme-instructed self-assembly of taxol promotes axonal branching

    Science.gov (United States)

    Mei, Bin; Miao, Qingqing; Tang, Anming; Liang, Gaolin

    2015-09-01

    Axonal branching is important for vertebrate neuron signaling. Taxol has a biphasic effect on axonal branching (i.e., high concentration inhibits axonal growth but low concentration restores it). To the best of our knowledge, low concentration of taxol to promote axonal branching has not been reported yet. Herein, we rationally designed a taxol derivative Fmoc-Phe-Phe-Lys(taxol)-Tyr(H2PO4)-OH (1) which could be subjected to alkaline phosphatase (ALP)-catalyzed self-assembly to form taxol nanofibers. We found that, at 10 μM, 1 has a microtubule (MT) condensation effect similar to that of taxol on mammalian cells but with more chronic toxicity than taxol on the cells. At a low concentration of 10 nM, 1 not only promoted neurite elongation as taxol did but also promoted axonal branching which was not achieved by using taxol. We propose that self-assembly of 1 along the MTs prohibited their lateral contacts and thus promoted axonal branching. Our strategy of enzyme-instructed self-assembly (EISA) of a taxol derivative provides a new tool for scientists to study the morphology of neurons, as well as their behaviours.Axonal branching is important for vertebrate neuron signaling. Taxol has a biphasic effect on axonal branching (i.e., high concentration inhibits axonal growth but low concentration restores it). To the best of our knowledge, low concentration of taxol to promote axonal branching has not been reported yet. Herein, we rationally designed a taxol derivative Fmoc-Phe-Phe-Lys(taxol)-Tyr(H2PO4)-OH (1) which could be subjected to alkaline phosphatase (ALP)-catalyzed self-assembly to form taxol nanofibers. We found that, at 10 μM, 1 has a microtubule (MT) condensation effect similar to that of taxol on mammalian cells but with more chronic toxicity than taxol on the cells. At a low concentration of 10 nM, 1 not only promoted neurite elongation as taxol did but also promoted axonal branching which was not achieved by using taxol. We propose that self-assembly of 1

  4. Identifying motor and sensory myelinated axons in rabbit peripheral nerves by histochemical staining for carbonic anhydrase and cholinesterase activities

    Science.gov (United States)

    Riley, Danny A.; Sanger, James R.; Matloub, Hani S.; Yousif, N. John; Bain, James L. W.

    1988-01-01

    Carbonic anhydrase (CA) and cholinesterase (CE) histochemical staining of rabbit spinal nerve roots and dorsal root ganglia demonstrated that among the reactive myeliated axons, with minor exceptions, sensory axons were CA positive and CE negative whereas motor axons were CA negative and CE positive. The high specificity was achieved by adjusting reaction conditions to stain subpopulations of myelinated axons selectively while leaving 50 percent or so unstained. Fixation with glutaraldehyde appeared necessary for achieving selectivity. Following sciatic nerve transection, the reciprocal staining pattern persisted in damaged axons and their regenerating processes which formed neuromas within the proximal nerve stump. Within the neuromas, CA-stained sensory processes were elaborated earlier and in greater numbers than CE-stained regenerating motor processes. The present results indicate that histochemical axon typing can be exploited to reveal heterogeneous responses of motor and sensory axons to injury.

  5. Guidance of Drosophila Mushroom Body Axons Depends upon DRL-Wnt Receptor Cleavage in the Brain Dorsomedial Lineage Precursors

    Directory of Open Access Journals (Sweden)

    Elodie Reynaud

    2015-05-01

    Full Text Available In vivo axon pathfinding mechanisms in the neuron-dense brain remain relatively poorly characterized. We study the Drosophila mushroom body (MB axons, whose α and β branches connect to different brain areas. We show that the Ryk family WNT5 receptor, DRL (derailed, which is expressed in the dorsomedial lineages, brain structure precursors adjacent to the MBs, is required for MB α branch axon guidance. DRL acts to capture and present WNT5 to MB axons rather than transduce a WNT5 signal. DRL’s ectodomain must be cleaved and shed to guide α axons. DRL-2, another Ryk, is expressed within MB axons and functions as a repulsive WNT5 signaling receptor. Finally, our biochemical data support the existence of a ternary complex composed of the cleaved DRL ectodomain, WNT5, and DRL-2. Thus, the interaction of MB-extrinsic and -intrinsic Ryks via their common ligand acts to guide MB α axons.

  6. Downregulation of glutamine synthetase via GLAST suppression induces retinal axonal swelling in a rat ex vivo hydrostatic pressure model.

    Science.gov (United States)

    Ishikawa, Makoto; Yoshitomi, Takeshi; Zorumski, Charles F; Izumi, Yukitoshi

    2011-08-01

    PURPOSE. High levels of glutamate can be toxic to retinal GCs. Thus, effective buffering of extracellular glutamate is important in preserving retinal structure and function. GLAST, a major glutamate transporter in the retina, and glutamine synthetase (GS) regulate extracellular glutamate accumulation and prevent excitotoxicity. This study was an examination of changes in function and expression of GLAST and GS in ex vivo rat retinas exposed to acute increases in ambient pressure. METHODS. Ex vivo rat retinas were exposed to elevated hydrostatic pressure for 24 hours. The expression of GLAST and GS were examined using immunochemistry and real-time PCR analysis. Also examined were the effects of (2S,3S)-3-[3-[4-(trifluoromethyl) benzoylamino] benzyloxy] aspartate (TFB-TBOA), an inhibitor of glutamate transporters, and l-methionine-S-sulfoximine (MSO), an inhibitor of GS. RESULTS. In this acute model, Western blot and real-time RT-PCR analyses revealed that substantially (75 mm Hg), but not moderately (35 mm Hg), elevated pressure depressed GLAST expression, diminished GS activity, and induced axonal swelling between the GC layer and the inner limiting membrane. However, at the moderately elevated pressure (35 mm Hg), administration of either TFB-TBOA or MSO also induced axonal swelling and excitotoxic neuronal damage. MSO did not depress GLAST expression but TFB-TBOA significantly suppressed GS, suggesting that downregulation of GS during pressure loading may result from impaired GLAST expression. CONCLUSIONS. The retina is at risk during acute intraocular pressure elevation due to downregulation of GS activity resulting from depressed GLAST expression. PMID:21775659

  7. Differences in the labeling of axons of passage by wheat germ agglutinin after uptake by cut peripheral nerve versus injections within the central nervous system

    International Nuclear Information System (INIS)

    Injections of a radiolabeled derivative of wheat germ agglutinin (WGA) in the subcortical white matter of the cerebral cortex in mice do not give rise to autoradiographic labeling of axon systems coursing through this fiber mass. Exposing the cut-end of mouse tibial nerve to WGA does, however, produce labeling within dorsal root ganglia and the spinal cord. These findings are discussed with consideration for dissimilarity in mode of central versus peripheral administration of the tracer, as well as in the light of potential relative differences in the uptake and transport of WGA and HRP. (Auth.)

  8. The Actin-Binding Protein α-Adducin Is Required for Maintaining Axon Diameter.

    Science.gov (United States)

    Leite, Sérgio Carvalho; Sampaio, Paula; Sousa, Vera Filipe; Nogueira-Rodrigues, Joana; Pinto-Costa, Rita; Peters, Luanne Laurel; Brites, Pedro; Sousa, Mónica Mendes

    2016-04-19

    The actin-binding protein adducin was recently identified as a component of the neuronal subcortical cytoskeleton. Here, we analyzed mice lacking adducin to uncover the function of this protein in actin rings. α-adducin knockout mice presented progressive axon enlargement in the spinal cord and optic and sciatic nerves, followed by axon degeneration and loss. Using stimulated emission depletion super-resolution microscopy, we show that a periodic subcortical actin cytoskeleton is assembled in every neuron type inspected including retinal ganglion cells and dorsal root ganglia neurons. In neurons devoid of adducin, the actin ring diameter increased, although the inter-ring periodicity was maintained. In vitro, the actin ring diameter adjusted as axons grew, suggesting the lattice is dynamic. Our data support a model in which adducin activity is not essential for actin ring assembly and periodicity but is necessary to control the diameter of both actin rings and axons and actin filament growth within rings. PMID:27068466

  9. Vertebrate Fidgetin Restrains Axonal Growth by Severing Labile Domains of Microtubules

    Directory of Open Access Journals (Sweden)

    Lanfranco Leo

    2015-09-01

    Full Text Available Individual microtubules (MTs in the axon consist of a stable domain that is highly acetylated and a labile domain that is not. Traditional MT-severing proteins preferentially cut the MT in the stable domain. In Drosophila, fidgetin behaves in this fashion, with targeted knockdown resulting in neurons with a higher fraction of acetylated (stable MT mass in their axons. Conversely, in a fidgetin knockout mouse, the fraction of MT mass that is acetylated is lower than in the control animal. When fidgetin is depleted from cultured rodent neurons, there is a 62% increase in axonal MT mass, all of which is labile. Concomitantly, there are more minor processes and a longer axon. Together with experimental data showing that vertebrate fidgetin targets unacetylated tubulin, these results indicate that vertebrate fidgetin (unlike its fly ortholog regulates neuronal development by tamping back the expansion of the labile domains of MTs.

  10. Calcium-Activated Potassium Channels at Nodes of Ranvier Secure Axonal Spike Propagation

    Directory of Open Access Journals (Sweden)

    Jan Gründemann

    2015-09-01

    Full Text Available Functional connectivity between brain regions relies on long-range signaling by myelinated axons. This is secured by saltatory action potential propagation that depends fundamentally on sodium channel availability at nodes of Ranvier. Although various potassium channel types have been anatomically localized to myelinated axons in the brain, direct evidence for their functional recruitment in maintaining node excitability is scarce. Cerebellar Purkinje cells provide continuous input to their targets in the cerebellar nuclei, reliably transmitting axonal spikes over a wide range of rates, requiring a constantly available pool of nodal sodium channels. We show that the recruitment of calcium-activated potassium channels (IK, KCa3.1 by local, activity-dependent calcium (Ca2+ influx at nodes of Ranvier via a T-type voltage-gated Ca2+ current provides a powerful mechanism that likely opposes depolarizing block at the nodes and is thus pivotal to securing continuous axonal spike propagation in spontaneously firing Purkinje cells.

  11. Calcium-dependent proteasome activation is required for axonal neurofilament degradation

    Institute of Scientific and Technical Information of China (English)

    Joo Youn Park; So Young Jang; Yoon Kyung Shin; Duk Joon Suh; Hwan Tae Park

    2013-01-01

    Even though many studies have identified roles of proteasomes in axonal degeneration, the mo-lecular mechanisms by which axonal injury regulates proteasome activity are stil unclear. In the present study, we found evidence indicating that extracellular calcium influx is an upstream regula-tor of proteasome activity during axonal degeneration in injured peripheral nerves. In degenerating axons, the increase in proteasome activity and the degradation of ubiquitinated proteins were sig-nificantly suppressed by extracellular calcium chelation. In addition, electron microscopic findings revealed selective inhibition of neurofilament degradation, but not microtubule depolymerization or mitochondrial swel ing, by the inhibition of calpain and proteasomes. Taken together, our findings suggest that calcium increase and subsequent proteasome activation are an essential initiator of neurofilament degradation in Wal erian degeneration.

  12. Calcium-dependent proteasome activation is required for axonal neurofilament degradation.

    Science.gov (United States)

    Park, Joo Youn; Jang, So Young; Shin, Yoon Kyung; Suh, Duk Joon; Park, Hwan Tae

    2013-12-25

    Even though many studies have identified roles of proteasomes in axonal degeneration, the molecular mechanisms by which axonal injury regulates proteasome activity are still unclear. In the present study, we found evidence indicating that extracellular calcium influx is an upstream regulator of proteasome activity during axonal degeneration in injured peripheral nerves. In degenerating axons, the increase in proteasome activity and the degradation of ubiquitinated proteins were significantly suppressed by extracellular calcium chelation. In addition, electron microscopic findings revealed selective inhibition of neurofilament degradation, but not microtubule depolymerization or mitochondrial swelling, by the inhibition of calpain and proteasomes. Taken together, our findings suggest that calcium increase and subsequent proteasome activation are an essential initiator of neurofilament degradation in Wallerian degeneration. PMID:25206662

  13. Mechanisms of sodium channel clustering and its influence on axonal impulse conduction.

    Science.gov (United States)

    Freeman, Sean A; Desmazières, Anne; Fricker, Desdemona; Lubetzki, Catherine; Sol-Foulon, Nathalie

    2016-02-01

    The efficient propagation of action potentials along nervous fibers is necessary for animals to interact with the environment with timeliness and precision. Myelination of axons is an essential step to ensure fast action potential propagation by saltatory conduction, a process that requires highly concentrated voltage-gated sodium channels at the nodes of Ranvier. Recent studies suggest that the clustering of sodium channels can influence axonal impulse conduction in both myelinated and unmyelinated fibers, which could have major implications in disease, particularly demyelinating pathology. This comprehensive review summarizes the mechanisms governing the clustering of sodium channels at the peripheral and central nervous system nodes and the specific roles of their clustering in influencing action potential conduction. We further highlight the classical biophysical parameters implicated in conduction timing, followed by a detailed discussion on how sodium channel clustering along unmyelinated axons can impact axonal impulse conduction in both physiological and pathological contexts. PMID:26514731

  14. Microtubule stabilization reduces scarring and causes axon regeneration after spinal cord injury

    NARCIS (Netherlands)

    F. Hellal (Farida); A. Hurtado (Andres); J. Ruschel (Jörg); K.C. Flynn (Kevin); C.J. Laskowski (Claudia); M. Umlauf (Martina); L.C. Kapitein (Lukas); D. Strikis (Dinara); V. Lemmon (Vance); J. Bixby (John); C.C. Hoogenraad (Casper); F. Bradke (Frank)

    2011-01-01

    textabstractHypertrophic scarring and poor intrinsic axon growth capacity constitute major obstacles for spinal cord repair. These processes are tightly regulated by microtubule dynamics. Here, moderate microtubule stabilization decreased scar formation after spinal cord injury in rodents through va

  15. Axonal degeneration in multiple sclerosis: defining therapeutic targets by identifying the causes of pathology.

    Science.gov (United States)

    Lee, Jae Young; Biemond, Melissa; Petratos, Steven

    2015-12-01

    Current therapeutics in multiple sclerosis (MS) target the putative inflammation and immune attack on CNS myelin. Despite their effectiveness in blunting the relapse rate in MS patients, such therapeutics do not prevent MS disease progression. Importantly, specific clinical dilemma arises through inability to predict MS progression and thereby therapeutically target axonal injury during MS, limiting permanent disability. The current review identifies immune and neurobiological principles that govern the sequelae of axonal degeneration during MS disease progression. Defining the specific disease arbiters, inflammatory and autoimmune, oligodendrocyte dystrophy and degenerative myelin, we discuss a basis for a molecular mechanism in axons that may be targeted therapeutically, in spatial and temporal manner to limit axonal degeneration and thereby halt progression of MS. PMID:26619755

  16. Axonal degeneration stimulates the formation of NG2+ cells and oligodendrocytes in the mouse

    DEFF Research Database (Denmark)

    Nielsen, Helle Hvilsted; Ladeby, Rune; Drøjdahl, Nina;

    2006-01-01

    Proliferation of the adult NG2-expressing oligodendrocyte precursor cells has traditionally been viewed as a remyelination response ensuing from destruction of myelin and oligodendrocytes, and not to the axonal pathology that is also a characteristic of demyelinating disease. To better understand...... the response of the NG2+ cells to the different components of demyelinating pathology, we investigated the response of adult NG2+ cells to axonal degeneration in the absence of primary myelin or oligodendrocyte pathology. Axonal degeneration was induced in the hippocampal dentate gyrus of adult mice...... by transection of the entorhino-dentate perforant path projection. The acutely induced degeneration of axons and terminals resulted in a prompt response of NG2+ cells, consisting of morphological transformation, cellular proliferation, and upregulation of NG2 expression days 2-3 after surgery. This was followed...

  17. Skin incision induces expression of axonal regeneration-related genes in adult rat spinal sensory neurons

    OpenAIRE

    Hill, Caitlin E.; Harrison, Benjamin J; Rau, Kris K.; Hougland, M. Tyler; Bunge, Mary Bartlett; Lorne M. Mendell; Petruska, Jeffrey C.

    2010-01-01

    Skin incision and nerve injury both induce painful conditions. Incisional and post-surgical pain is believed to arise primarily from inflammation of tissue and the subsequent sensitization of peripheral and central neurons. The role of axonal regeneration-related processes in development of pain has only been considered when there has been injury to the peripheral nerve itself, even though tissue damage likely induces injury of resident axons. We sought to determine if skin incision would aff...

  18. Negative regulation of glial engulfment activity by Draper terminates glial responses to axon injury

    OpenAIRE

    Logan, Mary A.; Hackett, Rachel; Doherty, Johnna; Sheehan, Amy; Speese, Sean D.; Freeman, Marc R

    2012-01-01

    Neuronal injury elicits potent cellular responses from glia, but molecular pathways modulating glial activation, phagocytic function, and termination of reactive responses remain poorly defined. Here we show that positive or negative regulation of glial reponses to axon injury are molecularly encoded by unique isoforms of the Drosophila engulfment receptor Draper. Draper-I promotes engulfment of axonal debris through an immunoreceptor tyrosine-based activation motif (ITAM). In contrast, Drape...

  19. Molecular Diagnosis of Infantile Neuro axonal Dystrophy by Next Generation Sequencing

    OpenAIRE

    Goyal, Manisha; Bijarnia-Mahay, Sunita; Kingsmore, Stephen; Farrow, Emily; Saunders, Carol; Saxena, Renu; Verma, Ishwar C

    2014-01-01

    Infantile Neuro axonal Dystrophy (INAD), is a rare inherited neurological disorder which affects nerve axons causing progressive loss of mental skills, muscular control and vision. The authors present a case of 5.8-y-old girl with INAD who was diagnosed after Next Generation Sequencing (NGS). She was born to a non-consanguineous couple and presented with hypotonia, developmental delay followed by neuroregression and nystagmus after 2 years of age. On examination, bilateral horizontal nystagmu...

  20. A cortical astrocyte subpopulation inhibits axon growth in vitro and in vivo

    OpenAIRE

    Liu, Rui; Wang, Zhe; Gou, Lin; XU, HANPENG

    2015-01-01

    Astrocytes are the most heterogeneous and predominant glial cell type in the central nervous system. However, the functional significance of this heterogeneity remains to be elucidated. Following injury, damaged astrocytes inhibit axonal regeneration in vivo and in vitro. Cultured primary astrocytes are commonly considered good supportive substrates for neuron attachment and axon regeneration. However, it is not known whether different populations of cells in the heterogeneous astrocyte cultu...

  1. Wnt Signalling Promotes Actin Dynamics during Axon Remodelling through the Actin-Binding Protein Eps8.

    Directory of Open Access Journals (Sweden)

    Eleanna Stamatakou

    Full Text Available Upon arrival at their synaptic targets, axons slow down their growth and extensively remodel before the assembly of presynaptic boutons. Wnt proteins are target-derived secreted factors that promote axonal remodelling and synaptic assembly. In the developing spinal cord, Wnts secreted by motor neurons promote axonal remodelling of NT-3 responsive dorsal root ganglia neurons. Axon remodelling induced by Wnts is characterised by growth cone pausing and enlargement, processes that depend on the re-organisation of microtubules. However, the contribution of the actin cytoskeleton has remained unexplored. Here, we demonstrate that Wnt3a regulates the actin cytoskeleton by rapidly inducing F-actin accumulation in growth cones from rodent DRG neurons through the scaffold protein Dishevelled-1 (Dvl1 and the serine-threonine kinase Gsk3β. Importantly, these changes in actin cytoskeleton occurs before enlargement of the growth cones is evident. Time-lapse imaging shows that Wnt3a increases lamellar protrusion and filopodia velocity. In addition, pharmacological inhibition of actin assembly demonstrates that Wnt3a increases actin dynamics. Through a yeast-two hybrid screen, we identified the actin-binding protein Eps8 as a direct interactor of Dvl1, a scaffold protein crucial for the Wnt signalling pathway. Gain of function of Eps8 mimics Wnt-mediated axon remodelling, whereas Eps8 silencing blocks the axon remodelling activity of Wnt3a. Importantly, blockade of the Dvl1-Eps8 interaction completely abolishes Wnt3a-mediated axonal remodelling. These findings demonstrate a novel role for Wnt-Dvl1 signalling through Eps8 in the regulation of axonal remodeling.

  2. An Analysis of Direct Hippocampal Cortical Field CA1 Axonal Projections to Diencephalon in the Rat

    OpenAIRE

    Cenquizca, Lee A.; Swanson, Larry W.

    2006-01-01

    The hippocampal formation is generally considered essential for processing episodic memory. However, the structural organization of hippocampal afferent and efferent axonal connections is still not completely understood, although such information is critical to support functional hypotheses. The full extent of axonal projections from field CA1 to the interbrain (diencephalon) is analyzed here with the Phaseolus vulgaris-leucoagglutinin (PHAL) method. The ventral pole of field CA1 establishes ...

  3. Workflow and Atlas System for Brain-Wide Mapping of Axonal Connectivity in Rat

    OpenAIRE

    2011-01-01

    Detailed knowledge about the anatomical organization of axonal connections is important for understanding normal functions of brain systems and disease-related dysfunctions. Such connectivity data are typically generated in neuroanatomical tract-tracing experiments in which specific axonal connections are visualized in histological sections. Since journal publications typically only accommodate restricted data descriptions and example images, literature search is a cumbersome way to retrieve ...

  4. The statistical mapping of cerebral metabolism for patients with severe diffuse axonal injury

    International Nuclear Information System (INIS)

    We investigated metabolic patterns in severe diffuse axonal injury patients using three-dimensional stereotactic surface projection (3D-SSP) technique. (Material and methods) Subjects was defined as the 23 diffuse axonal injury patients having a Coma Remission Scale of < 20 points on the PET examination in chronic stage. Normal volunteers were selected as normal database. For normal volunteers and patients, FDG-PET was carried out and 3D-SSP analysis was performed in group. (authors)

  5. Purkinje cell axonal anatomy: quantifying morphometric changes in essential tremor versus control brains

    OpenAIRE

    Babij, Rachel; Lee, Michelle; Cortés, Etty; Vonsattel, Jean-Paul G.; Faust, Phyllis L.; Louis, Elan D.

    2013-01-01

    Growing clinical, neuro-imaging and post-mortem data have implicated the cerebellum as playing an important role in the pathogenesis of essential tremor. Aside from a modest reduction of Purkinje cells in some post-mortem studies, Purkinje cell axonal swellings (torpedoes) are present to a greater degree in essential tremor cases than controls. Yet a detailed study of more subtle morphometric changes in the Purkinje cell axonal compartment has not been undertaken. We performed a detailed morp...

  6. Sustained axon-glial signaling induces Schwann cell hyperproliferation, Remak bundle myelination, and tumorigenesis

    OpenAIRE

    Gómez-Sánchez, José A.; López de Armentia, Mikel; Luján, Rafael; Kessaris, Nicoletta; Richardson, William D.; Cabedo, Hugo

    2009-01-01

    Type III neuregulins exposed on axon surfaces control myelination of the peripheral nervous system. It has been shown, for example, that threshold levels of type IIIβ1a neuregulin dictate not only the myelination fate of axons but also myelin thickness. Here we show that another neuregulin isoform, type III-β3, plays a distinct role in myelination. Neuronal overexpression of this isoform in mice stimulates Schwann cell proliferation and dramatically enlarges peripheral nerves and ganglia -whi...

  7. Nitric oxide as a putative retinal axon pathfinding and target recognition cue in Xenopus laevis

    OpenAIRE

    Sara Berman; Andrea Morris

    2011-01-01

    Nitric oxide (NO) is an atypical neurotransmitter synthesized by the enzyme nitric oxide synthase (NOS) during many stages of the Xenopus laevis life cycle. This research investigates whether the gas NO is involved in axon guidance, the neurodevelopmental process in which axons travel through the brain to their appropriate target locations to form functional neural circuitry. Through immunocytochemistry and direct labeling of the NO gas with a fluorescent dye, we have found that NOS expressio...

  8. Axon-Schwann cell interactions during peripheral nerve regeneration in zebrafish larvae

    OpenAIRE

    Ceci, Maria Laura; Mardones-Krsulovic, Camila; SÁNCHEZ, MARIO; Valdivia, Leonardo E.; Allende, Miguel L

    2014-01-01

    Background Peripheral nerve injuries can severely affect the way that animals perceive signals from the surrounding environment. While damage to peripheral axons generally has a better outcome than injuries to central nervous system axons, it is currently unknown how neurons re-establish their target innervations to recover function after injury, and how accessory cells contribute to this task. Here we use a simple technique to create reproducible and localized injury in the posterior lateral...

  9. Mild hypothermia for treatment of diffuse axonal injury: a quantitative analysis of diffusion tensor imaging

    OpenAIRE

    Jing, Guojie; Yao, Xiaoteng; Li, Yiyi; Xie, Yituan; Li, Wang#x2019;an; LIU, Kejun; Jing, Yingchao; Li, Baisheng; Lv, Yifan; Ma, Baoxin

    2014-01-01

    Fractional anisotropy values in diffusion tensor imaging can quantitatively reflect the consistency of nerve fibers after brain damage, where higher values generally indicate less damage to nerve fibers. Therefore, we hypothesized that diffusion tensor imaging could be used to evaluate the effect of mild hypothermia on diffuse axonal injury. A total of 102 patients with diffuse axonal injury were randomly divided into two groups: normothermic and mild hypothermic treatment groups. Patient's m...

  10. Microtubules Have Opposite Orientation in Axons and Dendrites of Drosophila Neurons

    OpenAIRE

    Stone, Michelle C.; Roegiers, Fabrice; Rolls, Melissa M

    2008-01-01

    In vertebrate neurons, axons have a uniform arrangement of microtubules with plus ends distal to the cell body (plus-end-out), and dendrites have equal numbers of plus- and minus-end-out microtubules. To determine whether microtubule orientation is a conserved feature of axons and dendrites, we analyzed microtubule orientation in invertebrate neurons. Using microtubule plus end dynamics, we mapped microtubule orientation in Drosophila sensory neurons, interneurons, and motor neurons. As expec...

  11. Axonal neuregulin 1 is a rate limiting but not essential factor for nerve remyelination

    OpenAIRE

    Fricker, Florence R.; Antunes-Martins, Ana; Galino, Jorge; Paramsothy, Remi; La Russa, Federica; Perkins, James; Goldberg, Rebecca; Brelstaff, Jack; Zhu, Ning; McMahon, Stephen B; Orengo, Christine; Garratt, Alistair N.; Birchmeier, Carmen; David L H Bennett

    2013-01-01

    Neuregulin 1 acts as an axonal signal that regulates multiple aspects of Schwann cell development including the survival and migration of Schwann cell precursors, the ensheathment of axons and subsequent elaboration of the myelin sheath. To examine the role of this factor in remyelination and repair following nerve injury, we ablated neuregulin 1 in the adult nervous system using a tamoxifen inducible Cre recombinase transgenic mouse system. The loss of neuregulin 1 impaired remyelination aft...

  12. Hydrogels as scaffolds and delivery systems to enhance axonal regeneration after injuries

    Directory of Open Access Journals (Sweden)

    Oscar A. Carballo-Molina

    2015-02-01

    Full Text Available Damage caused to neural tissue by disease or injury frequently produces a discontinuity in the nervous system. Such damage generates diverse alterations that are commonly permanent, due to the limited regeneration capacity of the adult nervous system, particularly the Central Nervous System (CNS. The cellular reaction to noxious stimulus leads to several events such as the formation of glial and fibrous scars, which inhibit axonal regeneration in both the CNS and the Peripheral Nervous System (PNS. Although in the PNS there is some degree of nerve regeneration, it is common that the growing axons reinnervate incorrect areas, causing mismatches. Providing a permissive substrate for axonal regeneration in combination with delivery systems for the release of molecules, which enhances axonal growth, could increase regeneration and the recovery of functions in the CNS or the PNS. Currently, there are no effective vehicles to supply growth factors or cells to the damaged/diseased nervous system. Hydrogels are polymers that are biodegradable, biocompatible and have the capacity to deliver a large range of molecules in situ. The inclusion of cultured neural cells into hydrogels forming three-dimensional structures allows the formation of synapses and neuronal survival. There is also evidence showing that hydrogels constitute an amenable substrate for axonal growth of endogenous or grafted cells, overcoming the presence of axonal regeneration inhibitory molecules, in both the central and peripheral nervous systems. Recent experiments suggest that hydrogels can carry and deliver several proteins relevant for improving neuronal survival and axonal growth. Although the use of hydrogels is appealing, its effectiveness is still a matter of discussion, and more results are needed to achieve consistent recovery using different parameters. This review also discusses areas of opportunity where hydrogels can be applied, in order to promote axonal regeneration of

  13. Fisiopatología del síndrome de Guillain Barré axonal Physiopathology of axonal acute Guillain Barré syndrome

    OpenAIRE

    Juan Guillermo Montoya Ch.; Diana P. Martínez T.; Jaime Carrizosa Moog; Beatriz Aguirre L.

    2002-01-01

    Se describe la fisiopatología del síndrome de Guillain Barré axonal. Se consideran especialmente cinco aspectos: 1) Agentes etiológicos, específicamente el Campylobacter jejuni. 2) Susceptibilidad genética humana. 3) Mimetismo molecular entre lipopolisacáridos y lipoproteínas. 4) Mecanismo de acción de los anticuerpos antigangliósidos y 5) Hallazgos patológicos. The physiopathology of axonal acute Guillain Barré syndrome is described. Five aspects are considered, namely: 1) Etiologic agents e...

  14. The clinical findings and CT diagnosis of diffuse axonal injury

    International Nuclear Information System (INIS)

    Objective: To investigate the clinical manifestations, characteristic CT findings and pathologic mechanism of diffuse axonal injury(DAI). Methods: The clinical materials and CT images of 58 cases of DAI were analyzed. Results: The clinical findings of DAI: (1) an acceleration or deceleration and spiral injury of head; (2) immediate coma after injury; (3) abnormalities of vital sign; (4) alternated muscle tone of extremities; (5) absence of local neurological sign. The diagnostic criterions of CT images: (1) multiple hemorrhagic lesions smaller than 2cm in diameter at the cortex-medulla junction or the axial area; (2) diffuse cerebral swellings; (3) general decompression and even disappearance of ventricles and cisterns; (4)non or moderate median structures dislocation (less than 5mm); (5) coexistence of other intra-cranial trauma. Conclusion: Combining with clinical findings and CT signs, a diagnosis of DAI can be established. Diffuse brain swelling (DBS) occurred by primary hypothalamus and vasomotor center of brain stem damaged is a special type. (authors)

  15. Sodium movements in perfused squid giant axons. Passive fluxes.

    Science.gov (United States)

    Rojas, E; Canessa-Fischer, M

    1968-08-01

    Sodium movements in internally perfused giant axons from the squid Dosidicus gigas were studied with varying internal sodium concentrations and with fluoride as the internal anion. It was found that as the internal concentration of sodium was increased from 2 to 200 mM the resting sodium efflux increased from 0.09 to 34.0 pmoles/cm(2)sec and the average resting sodium influx increased from 42.9 to 64.5 pmoles/cm(2)sec but this last change was not statistically significant. When perfusing with a mixture of 500 mM K glutamate and 100 mM Na glutamate the resting efflux was 10 +/- 3 pmoles/cm(2)sec and 41 +/- 10 pmoles/cm(2)sec for sodium influx. Increasing the internal sodium concentration also increased both the extra influx and the extra efflux of sodium due to impulse propagation. At any given internal sodium concentration the net extra influx was about 5 pmoles/cm(2)impulse. This finding supports the notion that the inward current generated in a propagated action potential can be completely accounted for by movements of sodium. PMID:5672003

  16. Metabolic efficiency with fast spiking in the squid axon

    Directory of Open Access Journals (Sweden)

    Abdelmalik Moujahid

    2012-11-01

    Full Text Available Fundamentally, action potentials in the squid axon are consequence of the entrance of sodium ions during the depolarization of the rising phase of the spike mediated by the outflow of potassium ions during the hyperpolarization of the falling phase. Perfect metabolic efficiency with a minimum charge needed for the change in voltage during the action potential would confine sodium entry to the rising phase and potassium efflux to the falling phase. However, because sodium channels remain open to a significant extent during the falling phase, a certain overlap of inward and outward currents is observed. In this work we investigate the impact of ion overlap on the number of the adenosine triphosphate (ATP molecules and energy cost required per action potential as a function of the temperature in a Hodgkin-Huxley model. Based on a recent approach to computing the energy cost of neuronal AP generation not based on ion counting, we show that increased firing frequencies induced by higher temperatures imply more efficient use of sodium entry, and then a decrease in the metabolic energy cost required to restore the concentration gradients after an action potential. Also, we determine values of sodium conductance at which the hydrolysis efficiency presents a clear minimum.

  17. Bridging Physics and Biology Using Resistance and Axons

    Science.gov (United States)

    Dyer, Joshua M.

    2014-11-01

    When teaching physics, it is often difficult to get biology-oriented students to see the relevance of physics.1 A complaint often heard is that biology students are required to take physics for the Medical College Admission Test (MCAT) as part of a "weeding out" process, but that they don't feel like they need physics for biology. Despite this impression held by students, there have been calls for better physics education for future physicians and life scientists.2,3 Research is being performed to improve physics classes and labs by linking topics in biology and physics.4,5 Described here is a laboratory experiment covering the topics of resistance of materials and circuits/Kirchhoff's laws in a biology context with their direct application to neurons, axons, and electrical impulse transmission within animals. This experiment will also demonstrate the mechanism believed to cause multiple sclerosis. The apparatus was designed with low-cost and readily available materials in mind.

  18. The neural adhesion molecule TAG-1 modulates responses of sensory axons to diffusible guidance signals.

    Science.gov (United States)

    Law, Chris O; Kirby, Rebecca J; Aghamohammadzadeh, Soheil; Furley, Andrew J W

    2008-08-01

    When the axons of primary sensory neurons project into the embryonic mammalian spinal cord, they bifurcate and extend rostrocaudally before sending collaterals to specific laminae according to neuronal subclass. The specificity of this innervation has been suggested to be the result both of differential sensitivity to chemorepellants expressed in the ventral spinal cord and of the function of Ig-like neural cell adhesion molecules in the dorsal horn. The relationship between these mechanisms has not been addressed. Focussing on the pathfinding of TrkA+ NGF-dependent axons, we demonstrate for the first time that their axons project prematurely into the dorsal horn of both L1 and TAG-1 knockout mice. We show that axons lacking TAG-1, similar to those lacking L1, are insensitive to wild-type ventral spinal cord (VSC)-derived chemorepellants, indicating that adhesion molecule function is required in the axons, and that this loss of response is explained in part by loss of response to Sema3A. We present evidence that TAG-1 affects sensitivity to Sema3A by binding to L1 and modulating the endocytosis of the L1/neuropilin 1 Sema3A receptor complex. However, TAG-1 appears to affect sensitivity to other VSC-derived chemorepellants via an L1-independent mechanism. We suggest that this dependence of chemorepellant sensitivity on the functions of combinations of adhesion molecules is important to ensure that axons project via specific pathways before extending to their final targets. PMID:18550718

  19. Effects of medium flow on axon growth with or without nerve growth factor.

    Science.gov (United States)

    Kumamoto, Junichi; Kitahata, Hiroyuki; Goto, Makiko; Nagayama, Masaharu; Denda, Mitsuhiro

    2015-09-11

    Axon growth is a crucial process in regeneration of damaged nerves. On the other hand, elongation of nerve fibers in the epidermis has been observed in skin of atopic dermatitis patients. Thus, regulation of nerve fiber extension might be an effective strategy to accelerate nerve regeneration and/or to reduce itching in pruritus dermatosis. We previously demonstrated that neurons and epidermal keratinocytes similarly contain multiple receptors that are activated by various environmental factors, and in particular, keratinocytes are influenced by shear stress. Thus, in the present study, we evaluated the effects of micro-flow of the medium on axon growth in the presence or absence of nerve growth factor (NGF), using cultured dorsal-root-ganglion (DRG) cells. The apparatus, AXIS™, consists of two chambers connected by a set of microgrooves, through which signaling molecules and axons, but not living cells, can pass. When DRG cells were present in chamber 1, NGF was present in chamber 2, and micro-flow was directed from chamber 1 to chamber 2, axon growth was significantly increased compared with other conditions. Acceleration of axon growth in the direction of the micro-flow was also observed in the absence of NGF. These results suggest that local micro-flow might significantly influence axon growth. PMID:26212442

  20. Distinct roles of neuropilin 1 signaling for radial and tangential extension of callosal axons.

    Science.gov (United States)

    Hatanaka, Yumiko; Matsumoto, Tomoko; Yanagawa, Yuchio; Fujisawa, Hajime; Murakami, Fujio; Masu, Masayuki

    2009-05-20

    Cortical excitatory neurons migrate from their origin in the ventricular zone (VZ) toward the pial surface. During migration, these neurons exhibit a stellate shape in the intermediate zone (IZ), transform into bipolar cells, and then initiate radial migration, extending a trailing process, which may lead to an axon. Here we examined the role of neuropilin 1 (NRP1) in these developmental events. Both NRP1 mRNA and protein were highly expressed in the IZ, where stellate-shaped cells were located. DiI labeling experiments showed that neuronal migration occurred normally in Nrp1 mutant mice up to embryonic day (E) 14.5, the latest day to which the mutant survives, with only subtle axonal defasciculation. However, interference with Nrp1 signaling at a later stage caused pathfinding errors: when a dominant negative form of Nrp1 was electroporated into the cortical VZ cells at E12.5 or E15.5 and examined perinatally, guidance errors were found in tangential axonal extension toward the midline. In contrast, no significant effect was noted on the migration of cortical excitatory neurons. These findings indicate that NRP1 plays an important role in the guidance of callosal axons originating from cortical excitatory neurons but does not support a role in their migration. Moreover, insofar as radial axonal extension within the cortical plate was unaffected, the present findings imply that molecular mechanisms for the axonal extension of excitatory neurons within the cortical plate are distinct from those in the white matter. PMID:19296474

  1. Enzyme-instructed self-assembly of taxol promotes axonal branching.

    Science.gov (United States)

    Mei, Bin; Miao, Qingqing; Tang, Anming; Liang, Gaolin

    2015-10-14

    Axonal branching is important for vertebrate neuron signaling. Taxol has a biphasic effect on axonal branching (i.e., high concentration inhibits axonal growth but low concentration restores it). To the best of our knowledge, low concentration of taxol to promote axonal branching has not been reported yet. Herein, we rationally designed a taxol derivative Fmoc-Phe-Phe-Lys(taxol)-Tyr(H2PO4)-OH (1) which could be subjected to alkaline phosphatase (ALP)-catalyzed self-assembly to form taxol nanofibers. We found that, at 10 μM, 1 has a microtubule (MT) condensation effect similar to that of taxol on mammalian cells but with more chronic toxicity than taxol on the cells. At a low concentration of 10 nM, 1 not only promoted neurite elongation as taxol did but also promoted axonal branching which was not achieved by using taxol. We propose that self-assembly of 1 along the MTs prohibited their lateral contacts and thus promoted axonal branching. Our strategy of enzyme-instructed self-assembly (EISA) of a taxol derivative provides a new tool for scientists to study the morphology of neurons, as well as their behaviours. PMID:26359218

  2. Human bone marrow mesenchymal stem cell transplantation attenuates axonal injur y in stroke rats

    Institute of Scientific and Technical Information of China (English)

    Yi Xu; Shiwei Du; Xinguang Yu; Xiao Han; Jincai Hou; Hao Guo

    2014-01-01

    Previous studies have shown that transplantation of human bone marrow mesenchymal stem cells promotes neural functional recovery after stroke, but the neurorestorative mechanisms remain largely unknown. We hypothesized that functional recovery of myelinated axons may be one of underlying mechanisms. In this study, an ischemia/reperfusion rat model was established using the middle cerebral artery occlusion method. Rats were used to test the hypothesis that in-travenous transplantation of human bone marrow mesenchymal stem cells through the femoral vein could exert neuroprotective effects against cerebral ischemia via a mechanism associated with the ability to attenuate axonal injury. The results of behavioral tests, infarction volume analysis and immunohistochemistry showed that cerebral ischemia caused severe damage to the myelin sheath and axons. After rats were intravenously transplanted with human bone marrow mesenchymal stem cells, the levels of axon and myelin sheath-related proteins, including mi-crotubule-associated protein 2, myelin basic protein, and growth-associated protein 43, were elevated, infarct volume was decreased and neural function was improved in cerebral ischemic rats. These ifndings suggest that intravenously transplanted human bone marrow mesenchymal stem cells promote neural function. Possible mechanisms underlying these beneifcial effects in-clude resistance to demyelination after cerebral ischemia, prevention of axonal degeneration, and promotion of axonal regeneration.

  3. Stochastic models of intracellular transport

    KAUST Repository

    Bressloff, Paul C.

    2013-01-09

    The interior of a living cell is a crowded, heterogenuous, fluctuating environment. Hence, a major challenge in modeling intracellular transport is to analyze stochastic processes within complex environments. Broadly speaking, there are two basic mechanisms for intracellular transport: passive diffusion and motor-driven active transport. Diffusive transport can be formulated in terms of the motion of an overdamped Brownian particle. On the other hand, active transport requires chemical energy, usually in the form of adenosine triphosphate hydrolysis, and can be direction specific, allowing biomolecules to be transported long distances; this is particularly important in neurons due to their complex geometry. In this review a wide range of analytical methods and models of intracellular transport is presented. In the case of diffusive transport, narrow escape problems, diffusion to a small target, confined and single-file diffusion, homogenization theory, and fractional diffusion are considered. In the case of active transport, Brownian ratchets, random walk models, exclusion processes, random intermittent search processes, quasi-steady-state reduction methods, and mean-field approximations are considered. Applications include receptor trafficking, axonal transport, membrane diffusion, nuclear transport, protein-DNA interactions, virus trafficking, and the self-organization of subcellular structures. © 2013 American Physical Society.

  4. Pioneer Axon Navigation Is Controlled by AEX-3, a Guanine Nucleotide Exchange Factor for RAB-3 in Caenorhabditis elegans.

    Science.gov (United States)

    Bhat, Jaffar M; Hutter, Harald

    2016-07-01

    Precise and accurate axon tract formation is an essential aspect of brain development. This is achieved by the migration of early outgrowing axons (pioneers) allowing later outgrowing axons (followers) to extend toward their targets in the embryo. In Caenorhabditis elegans the AVG neuron pioneers the right axon tract of the ventral nerve cord, the major longitudinal axon tract. AVG is essential for the guidance of follower axons and hence organization of the ventral nerve cord. In an enhancer screen for AVG axon guidance defects in a nid-1/Nidogen mutant background, we isolated an allele of aex-3 aex-3 mutant animals show highly penetrant AVG axon navigation defects. These defects are dependent on a mutation in nid-1/Nidogen, a basement membrane component. Our data suggest that AEX-3 activates RAB-3 in the context of AVG axon navigation. aex-3 genetically acts together with known players of vesicular exocytosis: unc-64/Syntaxin, unc-31/CAPS, and ida-1/IA-2. Furthermore our genetic interaction data suggest that AEX-3 and the UNC-6/Netrin receptor UNC-5 act in the same pathway, suggesting AEX-3 might regulate the trafficking and/or insertion of UNC-5 at the growth cone to mediate the proper guidance of the AVG axon. PMID:27116976

  5. Aggregation–fragmentation model of vesicular transport in neurons

    International Nuclear Information System (INIS)

    We develop a mathematical model of the motor-based transport and delivery of vesicles to synaptic targets of an axon. Our model incorporates the ‘stop-and-go’ nature of bidirectional motor transport (which can be modeled in terms of advection–diffusion) and the reversible exchange of vesicles between motors and targets, both of which have been observed experimentally. Since motor-target interactions are reversible, it is necessary to keep track of the cluster size of vesicles bound to each motor-complex. This naturally leads to a modified version of the Becker–Doring model of aggregation–fragmentation processes. We analyze steady-state solutions of the transport model and obtain an explicit solution that supports a uniform distribution of synaptic resources along an axon. We thus establish a possible mechanism for the democratic distribution of synaptic resources along the length of an axon, based on reversible motor-target interactions. In the irreversible case, one finds that the motor-driven transport of newly synthesized proteins from the soma to presynaptic targets along the axon tends to favor the delivery of resources to more proximal synapses. (paper)

  6. Retromer-Mediated Trafficking of Transmembrane Receptors and Transporters

    Directory of Open Access Journals (Sweden)

    Stine C. Klinger

    2015-07-01

    Full Text Available Transport between the endoplasmatic reticulum, the Golgi-network, the endo-lysosomal system and the cell surface can be categorized as anterograde or retrograde, describing traffic that goes forward or backward, respectively. Traffic going from the plasma membrane to endosomes and lysosomes or the trans-Golgi network (TGN constitutes the major retrograde transport routes. Several transmembrane proteins undergo retrograde transport as part of a recycling mechanism that contributes to reutilization and maintenance of a steady-state protein localization. In addition, some receptors are hijacked by exotoxins and used for entry and intracellular transport. The physiological relevance of retrograde transport cannot be overstated. Retrograde trafficking of the amyloid precursor protein determines the distribution between organelles, and hence the possibility of cleavage by γ-secretase. Right balancing of the pathways is critical for protection against Alzheimer’s disease. During embryonic development, retrograde transport of Wntless to the TGN is essential for the following release of Wnt from the plasma membrane. Furthermore, overexpression of Wntless has been linked to oncogenesis. Here, we review relevant aspects of the retrograde trafficking of mammalian transmembrane receptors and transporters, with focus on the retromer-mediated transport between endosomes and the TGN.

  7. Retromer-Mediated Trafficking of Transmembrane Receptors and Transporters.

    Science.gov (United States)

    Klinger, Stine C; Siupka, Piotr; Nielsen, Morten S

    2015-01-01

    Transport between the endoplasmatic reticulum, the Golgi-network, the endo-lysosomal system and the cell surface can be categorized as anterograde or retrograde, describing traffic that goes forward or backward, respectively. Traffic going from the plasma membrane to endosomes and lysosomes or the trans-Golgi network (TGN) constitutes the major retrograde transport routes. Several transmembrane proteins undergo retrograde transport as part of a recycling mechanism that contributes to reutilization and maintenance of a steady-state protein localization. In addition, some receptors are hijacked by exotoxins and used for entry and intracellular transport. The physiological relevance of retrograde transport cannot be overstated. Retrograde trafficking of the amyloid precursor protein determines the distribution between organelles, and hence the possibility of cleavage by γ-secretase. Right balancing of the pathways is critical for protection against Alzheimer's disease. During embryonic development, retrograde transport of Wntless to the TGN is essential for the following release of Wnt from the plasma membrane. Furthermore, overexpression of Wntless has been linked to oncogenesis. Here, we review relevant aspects of the retrograde trafficking of mammalian transmembrane receptors and transporters, with focus on the retromer-mediated transport between endosomes and the TGN. PMID:26154780

  8. α-Tubulin Tyrosination and CLIP-170 Phosphorylation Regulate the Initiation of Dynein-Driven Transport in Neurons.

    Science.gov (United States)

    Nirschl, Jeffrey J; Magiera, Maria M; Lazarus, Jacob E; Janke, Carsten; Holzbaur, Erika L F

    2016-03-22

    Motor-cargo recruitment to microtubules is often the rate-limiting step of intracellular transport, and defects in this recruitment can cause neurodegenerative disease. Here, we use in vitro reconstitution assays with single-molecule resolution, live-cell transport assays in primary neurons, computational image analysis, and computer simulations to investigate the factors regulating retrograde transport initiation in the distal axon. We find that phosphorylation of the cytoskeletal-organelle linker protein CLIP-170 and post-translational modifications of the microtubule track combine to precisely control the initiation of retrograde transport. Computer simulations of organelle dynamics in the distal axon indicate that while CLIP-170 primarily regulates the time to microtubule encounter, the tyrosination state of the microtubule lattice regulates the likelihood of binding. These mechanisms interact to control transport initiation in the axon in a manner sensitive to the specialized cytoskeletal architecture of the neuron. PMID:26972003

  9. EFFECTS OF P-XYLENE INHALATION ON AXONAL TRANSPORT IN THE RAT RETINAL GANGLION CELLS

    Science.gov (United States)

    Although the solvent xylene is suspected of producing nervous system dysfunction in animals and humans, little is known regarding the neurochemical consequences of xylene inhalation. he intent of this study was to determine the effect of intermittent, acute, and subchronic p-xyle...

  10. Matrix metalloproteinase 2 and membrane type 1 matrix metalloproteinase co-regulate axonal outgrowth of mouse retinal ganglion cells

    DEFF Research Database (Denmark)

    Gaublomme, Djoere; Buyens, Tom; De Groef, Lies; Stakenborg, Michelle; Janssens, Els; Ingvarsen, Signe; Porse, Astrid; Behrendt, Niels; Moons, Lieve

    2014-01-01

    , but not MMP-9, are involved in this process. Furthermore, administration of a novel antibody to MT1-MMP that selectively blocks pro-MMP-2 activation revealed a functional co-involvement of these proteinases in determining RGC axon outgrowth. Subsequent immunostainings showed expression of both MMP-2......, we were able to show that broad-spectrum MMP inhibition reduces axon outgrowth of mouse retinal ganglion cells (RGCs), implicating MMPs as beneficial factors in axonal regeneration. Additional studies, using more specific MMP inhibitors and MMP-deficient mice, disclosed that both MMP-2 and MT1-MMP...... and MT1-MMP in RGC axons and glial cells. Finally, results from combined inhibition of MMP-2 and β1-integrin were suggestive for a functional interaction between these molecules. Overall, our data indicate MMP-2 and MT1-MMP as promising axonal outgrowth-promoting molecules. Axonal regeneration in the...

  11. Filtration coefficient of the axon membrane as measured with hydrostatic and osmotic methods.

    Science.gov (United States)

    Vargas, F F

    1968-01-01

    The hydraulic conductivity of the membranes surrounding the giant axon of the squid, Dosidicus gigas, was measured. In some axons the axoplasm was partially removed by suction. Perfusion was then established by insertion of a second pipette. In other axons the axoplasm was left intact and only one pipette was inserted. In both groups hydrostatic pressure was applied by means of a water column in a capillary manometer. Displacement of the meniscus in time gave the rate of fluid flowing across the axon sheath. In both groups osmotic differences across the membrane were established by the addition of a test molecule to the external medium which was seawater. The hydraulic conductivity determined by application of hydrostatic pressure was 10.6 +/- 0.8.10(-8) cm/sec cm H(2)O in perfused axons and 3.2 +/- 0.6.10(-8) cm/sec cm H(2)O in intact axons. When the driving force was an osmotic pressure gradient the conductivity was 4.5 +/- 0.6 x 10(-10) cm/sec cm H(2)O and 4.8 +/- 0.9 x 10(-10) cm/sec cm H(2)O in perfused and intact axons, respectively. A comparable result was found when the internal solution was made hyperosmotic. The fluid flow was a linear function of the hydrostatic pressure up to 70 cm of water. Glycerol outflux and membrane conductance were increased 1.6 and 1.1 times by the application of hydrostatic pressure. These increments do not give an explanation of the difference between the filtration coefficients. Other possible explanations are suggested and discussed. PMID:5642470

  12. Rescuing axons from degeneration does not affect retinal ganglion cell death

    Directory of Open Access Journals (Sweden)

    S. de Lima

    2016-01-01

    Full Text Available After a traumatic injury to the central nervous system, the distal stumps of axons undergo Wallerian degeneration (WD, an event that comprises cytoskeleton and myelin breakdown, astrocytic gliosis, and overexpression of proteins that inhibit axonal regrowth. By contrast, injured neuronal cell bodies show features characteristic of attempts to initiate the regenerative process of elongating their axons. The main molecular event that leads to WD is an increase in the intracellular calcium concentration, which activates calpains, calcium-dependent proteases that degrade cytoskeleton proteins. The aim of our study was to investigate whether preventing axonal degeneration would impact the survival of retinal ganglion cells (RGCs after crushing the optic nerve. We observed that male Wistar rats (weighing 200-400 g; n=18 treated with an exogenous calpain inhibitor (20 mM administered via direct application of the inhibitor embedded within the copolymer resin Evlax immediately following optic nerve crush showed a delay in the onset of WD. This delayed onset was characterized by a decrease in the number of degenerated fibers (P<0.05 and an increase in the number of preserved fibers (P<0.05 4 days after injury. Additionally, most preserved fibers showed a normal G-ratio. These results indicated that calpain inhibition prevented the degeneration of optic nerve fibers, rescuing axons from the process of axonal degeneration. However, analysis of retinal ganglion cell survival demonstrated no difference between the calpain inhibitor- and vehicle-treated groups, suggesting that although the calpain inhibitor prevented axonal degeneration, it had no effect on RGC survival after optic nerve damage.

  13. A multi-component model of the developing retinocollicular pathway incorporating axonal and synaptic growth.

    Directory of Open Access Journals (Sweden)

    Keith B Godfrey

    2009-12-01

    Full Text Available During development, neurons extend axons to different brain areas and produce stereotypical patterns of connections. The mechanisms underlying this process have been intensively studied in the visual system, where retinal neurons form retinotopic maps in the thalamus and superior colliculus. The mechanisms active in map formation include molecular guidance cues, trophic factor release, spontaneous neural activity, spike-timing dependent plasticity (STDP, synapse creation and retraction, and axon growth, branching and retraction. To investigate how these mechanisms interact, a multi-component model of the developing retinocollicular pathway was produced based on phenomenological approximations of each of these mechanisms. Core assumptions of the model were that the probabilities of axonal branching and synaptic growth are highest where the combined influences of chemoaffinity and trophic factor cues are highest, and that activity-dependent release of trophic factors acts to stabilize synapses. Based on these behaviors, model axons produced morphologically realistic growth patterns and projected to retinotopically correct locations in the colliculus. Findings of the model include that STDP, gradient detection by axonal growth cones and lateral connectivity among collicular neurons were not necessary for refinement, and that the instructive cues for axonal growth appear to be mediated first by molecular guidance and then by neural activity. Although complex, the model appears to be insensitive to variations in how the component developmental mechanisms are implemented. Activity, molecular guidance and the growth and retraction of axons and synapses are common features of neural development, and the findings of this study may have relevance beyond organization in the retinocollicular pathway.

  14. Short-term peripheral nerve stimulation ameliorates axonal dysfunction after spinal cord injury.

    Science.gov (United States)

    Lee, Michael; Kiernan, Matthew C; Macefield, Vaughan G; Lee, Bonne B; Lin, Cindy S-Y

    2015-05-01

    There is accumulating evidence that peripheral motor axons deteriorate following spinal cord injury (SCI). Secondary axonal dysfunction can exacerbate muscle atrophy, contribute to peripheral neuropathies and neuropathic pain, and lead to further functional impairment. In an attempt to ameliorate the adverse downstream effects that developed following SCI, we investigated the effects of a short-term peripheral nerve stimulation (PNS) program on motor axonal excitability in 22 SCI patients. Axonal excitability studies were undertaken in the median and common peroneal nerves (CPN) bilaterally before and after a 6-wk unilateral PNS program. PNS was delivered percutaneously over the median nerve at the wrist and CPN around the fibular head, and the compound muscle action potential (CMAP) from the abductor pollicis brevis and tibialis anterior was recorded. Stimulus intensity was above motor threshold, and pulses (450 μs) were delivered at 100 Hz with a 2-s on/off cycle for 30 min 5 days/wk. SCI patients had consistently high thresholds with a reduced CMAP consistent with axonal loss; in some patients the peripheral nerves were completely inexcitable. Nerve excitability studies revealed profound changes in membrane potential, with a "fanned-in" appearance in threshold electrotonus, consistent with membrane depolarization, and significantly reduced superexcitability during the recovery cycle. These membrane dysfunctions were ameliorated after 6 wk of PNS, which produced a significant hyperpolarizing effect. The contralateral, nonstimulated nerves remained depolarized. Short-term PNS reversed axonal dysfunction following SCI, may provide an opportunity to prevent chronic changes in axonal and muscular function, and may improve rehabilitation outcomes. PMID:25787956

  15. Protein 4.1B contributes to the organization of peripheral myelinated axons.

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    Carmen Cifuentes-Diaz

    Full Text Available Neurons are characterized by extremely long axons. This exceptional cell shape is likely to depend on multiple factors including interactions between the cytoskeleton and membrane proteins. In many cell types, members of the protein 4.1 family play an important role in tethering the cortical actin-spectrin cytoskeleton to the plasma membrane. Protein 4.1B is localized in myelinated axons, enriched in paranodal and juxtaparanodal regions, and also all along the internodes, but not at nodes of Ranvier where are localized the voltage-dependent sodium channels responsible for action potential propagation. To shed light on the role of protein 4.1B in the general organization of myelinated peripheral axons, we studied 4.1B knockout mice. These mice displayed a mildly impaired gait and motility. Whereas nodes were unaffected, the distribution of Caspr/paranodin, which anchors 4.1B to the membrane, was disorganized in paranodal regions and its levels were decreased. In juxtaparanodes, the enrichment of Caspr2, which also interacts with 4.1B, and of the associated TAG-1 and Kv1.1, was absent in mutant mice, whereas their levels were unaltered. Ultrastructural abnormalities were observed both at paranodes and juxtaparanodes. Axon calibers were slightly diminished in phrenic nerves and preterminal motor axons were dysmorphic in skeletal muscle. βII spectrin enrichment was decreased along the axolemma. Electrophysiological recordings at 3 post-natal weeks showed the occurrence of spontaneous and evoked repetitive activity indicating neuronal hyperexcitability, without change in conduction velocity. Thus, our results show that in myelinated axons 4.1B contributes to the stabilization of membrane proteins at paranodes, to the clustering of juxtaparanodal proteins, and to the regulation of the internodal axon caliber.

  16. Primary neuron culture for nerve growth and axon guidance studies in zebrafish (Danio rerio.

    Directory of Open Access Journals (Sweden)

    Zheyan Chen

    Full Text Available Zebrafish (Danio rerio is a widely used model organism in genetics and developmental biology research. Genetic screens have proven useful for studying embryonic development of the nervous system in vivo, but in vitro studies utilizing zebrafish have been limited. Here, we introduce a robust zebrafish primary neuron culture system for functional nerve growth and guidance assays. Distinct classes of central nervous system neurons from the spinal cord, hindbrain, forebrain, and retina from wild type zebrafish, and fluorescent motor neurons from transgenic reporter zebrafish lines, were dissociated and plated onto various biological and synthetic substrates to optimize conditions for axon outgrowth. Time-lapse microscopy revealed dynamically moving growth cones at the tips of extending axons. The mean rate of axon extension in vitro was 21.4±1.2 µm hr(-1 s.e.m. for spinal cord neurons, which corresponds to the typical ∼0.5 mm day(-1 growth rate of nerves in vivo. Fluorescence labeling and confocal microscopy demonstrated that bundled microtubules project along axons to the growth cone central domain, with filamentous actin enriched in the growth cone peripheral domain. Importantly, the growth cone surface membrane expresses receptors for chemotropic factors, as detected by immunofluorescence microscopy. Live-cell functional assays of axon extension and directional guidance demonstrated mammalian brain-derived neurotrophic factor (BDNF-dependent stimulation of outgrowth and growth cone chemoattraction, whereas mammalian myelin-associated glycoprotein inhibited outgrowth. High-resolution live-cell Ca(2+-imaging revealed local elevation of cytoplasmic Ca(2+ concentration in the growth cone induced by BDNF application. Moreover, BDNF-induced axon outgrowth, but not basal outgrowth, was blocked by treatments to suppress cytoplasmic Ca(2+ signals. Thus, this primary neuron culture model system may be useful for studies of neuronal development

  17. Chlorpyrifos and chlorpyrifos-oxon inhibit axonal growth by interfering with the morphogenic activity of acetylcholinesterase

    International Nuclear Information System (INIS)

    A primary role of acetylcholinesterase (AChE) is regulation of cholinergic neurotransmission by hydrolysis of synaptic acetylcholine. In the developing nervous system, however, AChE also functions as a morphogenic factor to promote axonal growth. This raises the question of whether organophosphorus pesticides (OPs) that are known to selectively bind to and inactivate the enzymatic function of AChE also interfere with its morphogenic function to perturb axonogenesis. To test this hypothesis, we exposed primary cultures of sensory neurons derived from embryonic rat dorsal root ganglia (DRG) to chlorpyrifos (CPF) or its oxon metabolite (CPFO). Both OPs significantly decreased axonal length at concentrations that had no effect on cell viability, protein synthesis or the enzymatic activity of AChE. Comparative analyses of the effects of CPF and CPFO on axonal growth in DRG neurons cultured from AChE nullizygous (AChE-/-) versus wild type (AChE+/+) mice indicated that while these OPs inhibited axonal growth in AChE+/+ DRG neurons, they had no effect on axonal growth in AChE-/- DRG neurons. However, transfection of AChE-/- DRG neurons with cDNA encoding full-length AChE restored the wild type response to the axon inhibitory effects of OPs. These data indicate that inhibition of axonal growth by OPs requires AChE, but the mechanism involves inhibition of the morphogenic rather than enzymatic activity of AChE. These findings suggest a novel mechanism for explaining not only the functional deficits observed in children and animals following developmental exposure to OPs, but also the increased vulnerability of the developing nervous system to OPs

  18. Time-Lapse Imaging of the Dynamics of CNS Glial-Axonal Interactions In Vitro and Ex Vivo

    OpenAIRE

    Kalliopi Ioannidou; Anderson, Kurt I; David Strachan; Edgar, Julia M.; Barnett, Susan C.

    2012-01-01

    Background Myelination is an exquisite and dynamic example of heterologous cell-cell interaction, which consists of the concentric wrapping of multiple layers of oligodendrocyte membrane around neuronal axons. Understanding the mechanism by which oligodendrocytes ensheath axons may bring us closer to designing strategies to promote remyelination in demyelinating diseases. The main aim of this study was to follow glial-axonal interactions over time both in vitro and ex vivo to visualize th...

  19. Dynamics of degeneration and regeneration in developing zebrafish peripheral axons reveals a requirement for extrinsic cell types

    Directory of Open Access Journals (Sweden)

    Villegas Rosario

    2012-06-01

    Full Text Available Abstract Background Understanding the cellular mechanisms regulating axon degeneration and regeneration is crucial for developing treatments for nerve injury and neurodegenerative disease. In neurons, axon degeneration is distinct from cell body death and often precedes or is associated with the onset of disease symptoms. In the peripheral nervous system of both vertebrates and invertebrates, after degeneration of detached fragments, axons can often regenerate to restore function. Many studies of axonal degeneration and regeneration have used in vitro approaches, but the influence of extrinsic cell types on these processes can only be fully addressed in live animals. Because of its simplicity and superficial location, the larval zebrafish posterior lateral line (pLL nerve is an ideal model system for live studies of axon degeneration and regeneration. Results We used laser axotomy and time-lapse imaging of pLL axons to characterize the roles of leukocytes, Schwann cells and target sensory hair cells in axon degeneration and regeneration in vivo. Immune cells were essential for efficient removal of axonal debris after axotomy. Schwann cells were required for proper fasciculation and pathfinding of regenerating axons to their target cells. Intact target hair cells were not themselves required for regeneration, but chemical ablation of neuromasts caused axons to transiently deviate from their normal paths. Conclusions Macrophages, Schwann cells, and target sensory organs are required for distinct aspects of pLL axon degeneration or regeneration in the zebrafish larva. Our work introduces a powerful vertebrate model for analyzing axonal degeneration and regeneration in the living animal and elucidating the role of extrinsic cell types in these processes.

  20. The contributions of myelin and axonal caliber to transverse relaxation time in shiverer and neurofilament-deficient mouse models

    OpenAIRE

    Dyakin, Victor V.; Chen, Yuanxin; Branch, Craig A.; Veeranna; Yuan, Aidong; Rao, Mala; Kumar, Asok; Peterhoff, Corrinne M.; Nixon, Ralph A

    2010-01-01

    White matter disorders can involve injury to myelin or axons but the respective contribution of each to clinical course is difficult to evaluate non-invasively. Here, to develop a paradigm for further investigations of axonal pathology by MRI, we compared two genetic mouse models exhibiting relatively selective axonal or myelin deficits using quantitative MRI relaxography of the transverse relaxation times (T2) in vivo and ultrastructural morphometry. In HM-DKO mice, which lack genes encoding...

  1. L-carnitine enhances axonal plasticity and improves white-matter lesions after chronic hypoperfusion in rat brain

    OpenAIRE

    Ueno, Yuji; Koike, Masato; Shimada, Yoshiaki; Shimura, Hideki; Hira, Kenichiro; Tanaka, Ryota; Uchiyama, Yasuo; Hattori, Nobutaka; Urabe, Takao

    2014-01-01

    Chronic cerebral hypoperfusion causes white-matter lesions (WMLs) with oxidative stress and cognitive impairment. However, the biologic mechanisms that regulate axonal plasticity under chronic cerebral hypoperfusion have not been fully investigated. Here, we investigated whether L-carnitine, an antioxidant agent, enhances axonal plasticity and oligodendrocyte expression, and explored the signaling pathways that mediate axonal plasticity in a rat chronic hypoperfusion model. Adult male Wistar ...

  2. Ion channel clustering at the axon initial segment and node of Ranvier evolved sequentially in early chordates.

    OpenAIRE

    Hill, Alexis S.; Atsuo Nishino; Koichi Nakajo; Giuxin Zhang; Fineman, Jaime R.; Selzer, Michael E.; Yasushi Okamura; Cooper, Edward C.

    2008-01-01

    In many mammalian neurons, dense clusters of ion channels at the axonal initial segment and nodes of Ranvier underlie action potential generation and rapid conduction. Axonal clustering of mammalian voltage-gated sodium and KCNQ (Kv7) potassium channels is based on linkage to the actin–spectrin cytoskeleton, which is mediated by the adaptor protein ankyrin-G. We identified key steps in the evolution of this axonal channel clustering. The anchor motif for sodium channel clustering evolved earl...

  3. Squeezing axons out of the gray matter: a role for slit and semaphorin proteins from midline and ventral spinal cord.

    OpenAIRE

    Y. Zou; Stoeckli, E T; Chen, H.; Tessier-Lavigne, M

    2000-01-01

    Commissural axons cross the nervous system midline and then turn to grow alongside it, neither recrossing nor projecting back into ventral regions. In Drosophila, the midline repellent Slit prevents recrossing: axons cross once because they are initially unresponsive to Slit, becoming responsive only upon crossing. We show that commissural axons in mammals similarly acquire responsiveness to a midline repellent activity upon crossing. Remarkably, they also become responsive to a repellent act...

  4. A Purine-Sensitive Pathway Regulates Multiple Genes Involved in Axon Regeneration in Goldfish Retinal Ganglion Cells

    OpenAIRE

    Petrausch, Barbara; Tabibiazar, Raymond; Roser, Timo; Jing, Yun; Goldmann, Daniel; Stürmer, Claudia; Irwin, Nina; Benowitz, Larry I.

    2000-01-01

    In lower vertebrates, retinal ganglion cells (RGCs) can regenerate their axons and reestablish functional connections after optic nerve injury. We show here that in goldfish RGCs, the effects of several trophic factors converge on a purine-sensitive signaling mechanism that controls axonal outgrowth and the expression of multiple growth-associated proteins. In culture, goldfish RGCs regenerate their axons in response to two molecules secreted by optic nerve glia, axogenesis factor-1 (AF-1) an...

  5. Brain-derived neurotrophic factor gene transfection promotes neuronal repair and neurite regeneration after diffuse axonal injury

    Institute of Scientific and Technical Information of China (English)

    Yin Yu; Chao Du; Xingli Zhao; Jiajia Shao; Qiang Shen; Tao Jiang; Wei Wu; Dong Zhu; Yu Tian; Yongchuan Guo

    2011-01-01

    This study sought to assess the potential of brain-derived neurotrophic factor (BDNF) to promote neuronal repair and regeneration in rats with diffuse axonal injury, and to examine the accompanying neurobiological changes. BDNF gene transfection reduced the severity of the pathological changes associated with diffuse axonal injury in cortical neurons of the frontal lobe and increased neurofilament protein expression. These findings demonstrate that BDNF can effectively promote neuronal repair and neurite regeneration after diffuse axonal injury.

  6. The comparison of the value of ct imaging and selected MRI sequences (including DWI) in the evaluation of axonal injuries

    OpenAIRE

    Paszkowska, Emilia; Wasilewski, Grzegorz; Szalcunas-Olsztyn, Anna; Jancewicz, Patryk; Stefanowicz, Elżbieta

    2010-01-01

    Summary Background: Diffuse axonal injuries of the brain consist in the damage (overstretching or torsion) of white matter axons, as a result of the forces of energy waves, evoked in the moment of injury, together with its accelerating-retarding inertia effect. Patients with DAI are most frequently the casualties of high speed car accidents. Diffuse axonal injuries of the brain are one of the most common acute brain injuries, with lesions typically occurring in the periventricular white matte...

  7. Bergmann glia and the recognition molecule CHL1 organize GABAergic axons and direct innervation of Purkinje cell dendrites.

    Directory of Open Access Journals (Sweden)

    Fabrice Ango

    2008-04-01

    Full Text Available The geometric and subcellular organization of axon arbors distributes and regulates electrical signaling in neurons and networks, but the underlying mechanisms have remained elusive. In rodent cerebellar cortex, stellate interneurons elaborate characteristic axon arbors that selectively innervate Purkinje cell dendrites and likely regulate dendritic integration. We used GFP BAC transgenic reporter mice to examine the cellular processes and molecular mechanisms underlying the development of stellate cell axons and their innervation pattern. We show that stellate axons are organized and guided towards Purkinje cell dendrites by an intermediate scaffold of Bergmann glial (BG fibers. The L1 family immunoglobulin protein Close Homologue of L1 (CHL1 is localized to apical BG fibers and stellate cells during the development of stellate axon arbors. In the absence of CHL1, stellate axons deviate from BG fibers and show aberrant branching and orientation. Furthermore, synapse formation between aberrant stellate axons and Purkinje dendrites is reduced and cannot be maintained, leading to progressive atrophy of axon terminals. These results establish BG fibers as a guiding scaffold and CHL1 a molecular signal in the organization of stellate axon arbors and in directing their dendritic innervation.

  8. The impact of motor axon misdirection and attrition on behavioral deficit following experimental nerve injuries.

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    Jacob Daniel de Villiers Alant

    Full Text Available Peripheral nerve transection and neuroma-in-continuity injuries are associated with permanent functional deficits, often despite successful end-organ reinnervation. Axonal misdirection with non-specific reinnervation, frustrated regeneration and axonal attrition are believed to be among the anatomical substrates that underlie the poor functional recovery associated with these devastating injuries. Yet, functional deficits associated with axonal misdirection in experimental neuroma-in-continuity injuries have not yet been studied. We hypothesized that experimental neuroma-in-continuity injuries would result in motor axon misdirection and attrition with proportional persistent functional deficits. The femoral nerve misdirection model was exploited to assess major motor pathway misdirection and axonal attrition over a spectrum of experimental nerve injuries, with neuroma-in-continuity injuries simulated by the combination of compression and traction forces in 42 male rats. Sciatic nerve injuries were employed in an additional 42 rats, to evaluate the contribution of axonal misdirection to locomotor deficits by a ladder rung task up to 12 weeks. Retrograde motor neuron labeling techniques were utilized to determine the degree of axonal misdirection and attrition. Characteristic histological neuroma-in-continuity features were demonstrated in the neuroma-in-continuity groups and poor functional recovery was seen despite successful nerve regeneration and muscle reinnervation. Good positive and negative correlations were observed respectively between axonal misdirection (p<.0001, r(2=.67, motor neuron counts (attrition (p<.0001, r(2=.69 and final functional deficits. We demonstrate prominent motor axon misdirection and attrition in neuroma-in-continuity and transection injuries of mixed motor nerves that contribute to the long-term functional deficits. Although widely accepted in theory, to our knowledge, this is the first experimental evidence to

  9. Structural plasticity of GABAergic axons is regulated by network activity and GABAA receptor activation

    Directory of Open Access Journals (Sweden)

    Anne eSchuemann

    2013-06-01

    Full Text Available Coordinated changes at excitatory and inhibitory synapses are essential for normal brain development and function. It is well established that excitatory neurons undergo structural changes, but our knowledge about inhibitory structural plasticity is rather scarce. Here we present a quantitative analysis of the dynamics of GABAergic boutons in the dendritic region of the hippocampal CA1 area using time-lapse two-photon imaging in organotypic hippocampal cultures from GAD65-GFP mice. We show that ~20% of inhibitory boutons are not stable. They are appearing, disappearing and reappearing at specific locations along the inhibitory axon and reflect immature or incomplete synapses. Furthermore, we observed that persistent boutons show large volume fluctuations over several hours, suggesting that presynaptic content of inhibitory synapses is not constant. Our data show that inhibitory boutons are highly dynamic structures and suggest that inhibitory axons are continuously probing potential locations for inhibitory synapse formation by redistributing presynaptic material along the axon.In addition, we found that neuronal activity affects the exploratory dynamics of inhibitory axons. Blocking network activity rapidly reduces the number of transient boutons, whereas enhancing activity reduces the number of persistent inhibitory boutons, possibly reflecting enhanced competition between boutons along the axon. The latter effect requires signaling through GABAA receptors. We propose that activity-dependent regulation of bouton dynamics contributes to inhibitory synaptic plasticity.

  10. A Mathematical Model of Regenerative Axon Growing along Glial Scar after Spinal Cord Injury

    Science.gov (United States)

    Chen, Xuning; Zhu, Weiping

    2016-01-01

    A major factor in the failure of central nervous system (CNS) axon regeneration is the formation of glial scar after the injury of CNS. Glial scar generates a dense barrier which the regenerative axons cannot easily pass through or by. In this paper, a mathematical model was established to explore how the regenerative axons grow along the surface of glial scar or bypass the glial scar. This mathematical model was constructed based on the spinal cord injury (SCI) repair experiments by transplanting Schwann cells as bridge over the glial scar. The Lattice Boltzmann Method (LBM) was used in this model for three-dimensional numerical simulation. The advantage of this model is that it provides a parallel and easily implemented algorithm and has the capability of handling complicated boundaries. Using the simulated data, two significant conclusions were made in this study: (1) the levels of inhibitory factors on the surface of the glial scar are the main factors affecting axon elongation and (2) when the inhibitory factor levels on the surface of the glial scar remain constant, the longitudinal size of the glial scar has greater influence on the average rate of axon growth than the transverse size. These results will provide theoretical guidance and reference for researchers to design efficient experiments.

  11. X11/Mint genes control polarized localization of axonal membrane proteins in vivo.

    Science.gov (United States)

    Gross, Garrett G; Lone, G Mohiddin; Leung, Lok Kwan; Hartenstein, Volker; Guo, Ming

    2013-05-01

    Mislocalization of axonal proteins can result in misassembly and/or miswiring of neural circuits, causing disease. To date, only a handful of genes that control polarized localization of axonal membrane proteins have been identified. Here we report that Drosophila X11/Mint proteins are required for targeting several proteins, including human amyloid precursor protein (APP) and Drosophila APP-like protein (APPL), to axonal membranes and for their exclusion from dendrites of the mushroom body in Drosophila, a brain structure involved in learning and memory. Axonal localization of APP is mediated by an endocytic motif, and loss of X11/Mint results in a dramatic increase in cell-surface levels of APPL, especially on dendrites. Mutations in genes required for endocytosis show similar mislocalization of these proteins to dendrites, and strongly enhance defects seen in X11/Mint mutants. These results suggest that X11/Mint-dependent endocytosis in dendrites may serve to promote the axonal localization of membrane proteins. Since X11/Mint binds to APP, and abnormal trafficking of APP contributes to Alzheimer's disease, deregulation of X11/Mint may be important for Alzheimer's disease pathogenesis. PMID:23658195

  12. A large fraction of neocortical myelin ensheathes axons of local inhibitory neurons

    Science.gov (United States)

    Micheva, Kristina D; Wolman, Dylan; Mensh, Brett D; Pax, Elizabeth; Buchanan, JoAnn; Smith, Stephen J; Bock, Davi D

    2016-01-01

    Myelin is best known for its role in increasing the conduction velocity and metabolic efficiency of long-range excitatory axons. Accordingly, the myelin observed in neocortical gray matter is thought to mostly ensheath excitatory axons connecting to subcortical regions and distant cortical areas. Using independent analyses of light and electron microscopy data from mouse neocortex, we show that a surprisingly large fraction of cortical myelin (half the myelin in layer 2/3 and a quarter in layer 4) ensheathes axons of inhibitory neurons, specifically of parvalbumin-positive basket cells. This myelin differs significantly from that of excitatory axons in distribution and protein composition. Myelin on inhibitory axons is unlikely to meaningfully hasten the arrival of spikes at their pre-synaptic terminals, due to the patchy distribution and short path-lengths observed. Our results thus highlight the need for exploring alternative roles for myelin in neocortical circuits. DOI: http://dx.doi.org/10.7554/eLife.15784.001 PMID:27383052

  13. Electro-stimulation of cerebellar fastigial nucleus (FNS) improves axonal regeneration.

    Science.gov (United States)

    Zhang, Shuyan; Zhang, Qinli; Zhang, John H; Qin, Xinyue

    2008-01-01

    This study focused on the effect of electro-stimulation of fastigial nucleus on the expression of NgR and on axonal regeneration after focal cerebral ischemia-reperfusion in rats. Cerebral ischemia and reperfusion was induced by nylon monofilament. Ninety-six male SD rats were randomly divided into sham group and ischemic insult groups at 12 hours, 24 hours, and 1 to 3 weeks after cerebral ischemia-reperfusion. Reverse transcription-polymerase chain reaction (RT-PCR) was used to determine the changes of NgR mRNA expression. Immunohistochemistry was used to detect the expression of NgR protein and the state of axonal regeneration. Fastigial nucleus stimulation was applied at 2 hours after ischemia for one hour. The results demonstrated that NgR mRNA and protein in the infarcted cortex and hippocampus were significantly increased (p<0.01). The axons were grossly damaged at 24 h after cerebral ischemia-reperfusion when compared to the sham group. Fastigial nucleus stimulation decreased NgR mRNA and protein levels in the infarcted cortex and hippocampus (p<0.01) and improved axonal growth at 24 hours and 2 weeks after ischemia-reperfusion (p<0.05). These results suggest that electrostimulation of fastigial nucleus might provide a new strategy to promote CNS axonal regeneration. PMID:18508711

  14. Altered potassium channel distribution and composition in myelinated axons suppresses hyperexcitability following injury.

    Science.gov (United States)

    Calvo, Margarita; Richards, Natalie; Schmid, Annina B; Barroso, Alejandro; Zhu, Lan; Ivulic, Dinka; Zhu, Ning; Anwandter, Philipp; Bhat, Manzoor A; Court, Felipe A; McMahon, Stephen B; Bennett, David L H

    2016-01-01

    Neuropathic pain following peripheral nerve injury is associated with hyperexcitability in damaged myelinated sensory axons, which begins to normalise over time. We investigated the composition and distribution of shaker-type-potassium channels (Kv1 channels) within the nodal complex of myelinated axons following injury. At the neuroma that forms after damage, expression of Kv1.1 and 1.2 (normally localised to the juxtaparanode) was markedly decreased. In contrast Kv1.4 and 1.6, which were hardly detectable in the naïve state, showed increased expression within juxtaparanodes and paranodes following injury, both in rats and humans. Within the dorsal root (a site remote from injury) we noted a redistribution of Kv1-channels towards the paranode. Blockade of Kv1 channels with α-DTX after injury reinstated hyperexcitability of A-fibre axons and enhanced mechanosensitivity. Changes in the molecular composition and distribution of axonal Kv1 channels, therefore represents a protective mechanism to suppress the hyperexcitability of myelinated sensory axons that follows nerve injury. PMID:27033551

  15. Formation of compact myelin is required for maturation of the axonal cytoskeleton

    Science.gov (United States)

    Brady, S. T.; Witt, A. S.; Kirkpatrick, L. L.; de Waegh, S. M.; Readhead, C.; Tu, P. H.; Lee, V. M.

    1999-01-01

    Although traditional roles ascribed to myelinating glial cells are structural and supportive, the importance of compact myelin for proper functioning of the nervous system can be inferred from mutations in myelin proteins and neuropathologies associated with loss of myelin. Myelinating Schwann cells are known to affect local properties of peripheral axons (de Waegh et al., 1992), but little is known about effects of oligodendrocytes on CNS axons. The shiverer mutant mouse has a deletion in the myelin basic protein gene that eliminates compact myelin in the CNS. In shiverer mice, both local axonal features like phosphorylation of cytoskeletal proteins and neuronal perikaryon functions like cytoskeletal gene expression are altered. This leads to changes in the organization and composition of the axonal cytoskeleton in shiverer unmyelinated axons relative to age-matched wild-type myelinated fibers, although connectivity and patterns of neuronal activity are comparable. Remarkably, transgenic shiverer mice with thin myelin sheaths display an intermediate phenotype indicating that CNS neurons are sensitive to myelin sheath thickness. These results indicate that formation of a normal compact myelin sheath is required for normal maturation of the neuronal cytoskeleton in large CNS neurons.

  16. Laminin/β1 integrin signal triggers axon formation by promoting microtubule assembly and stabilization

    Institute of Scientific and Technical Information of China (English)

    Wen-Liang Lei; Shi-Ge Xing; Cai-Yun Deng; Xiang-Chun Ju; Xing-Yu Jiang; Zhen-Ge Luo

    2012-01-01

    Axon specification during neuronal polarization is closely associated with increased microtubule stabilization in one of the neurites of unpolarized neuron,but how this increased microtubule stability is achieved is unclear.Here,we show that extracellular matrix (ECM) component laminin promotes neuronal polarization via regulating directional microtubule assembly through β1 integrin (Itgb1).Contact with laminin coated on culture substrate or polystyrene beads was sufficient for axon specification of undifferentiated neurites in cultured hippocampal neurons and cortical slices.Active Itgb1 was found to be concentrated in laminin-contacting neurites.Axon formation was promoted and abolished by enhancing and attenuating Itgbl signaling,respectively.Interestingly,laminin contact promoted plus-end microtubule assembly in a manner that required Itgbl.Moreover,stabilizing microtubules partially prevented polarization defects caused by ltgbl downregulation.Finally,genetic ablation of ltgbl in dorsal telencephalic progenitors caused deficits in axon development of cortical pyramidal neurons.Thus,laminin/Itgb1 signaling plays an instructive role in axon initiation and growth,both in vitro and in vivo,through the regulation of microtubule assembly.This study has established a linkage between an extrinsic factor and intrinsic cytoskeletai dynamics during neuronal polarization.

  17. 3D Axon structure extraction and analysis in confocal fluorescence microscopy images.

    Science.gov (United States)

    Zhang, Yong; Zhou, Xiaobo; Lu, Ju; Lichtman, Jeff; Adjeroh, Donald; Wong, Stephen T C

    2008-08-01

    The morphological properties of axons, such as their branching patterns and oriented structures, are of great interest for biologists in the study of the synaptic connectivity of neurons. In these studies, researchers use triple immunofluorescent confocal microscopy to record morphological changes of neuronal processes. Three-dimensional (3D) microscopy image analysis is then required to extract morphological features of the neuronal structures. In this article, we propose a highly automated 3D centerline extraction tool to assist in this task. For this project, the most difficult part is that some axons are overlapping such that the boundaries distinguishing them are barely visible. Our approach combines a 3D dynamic programming (DP) technique and marker-controlled watershed algorithm to solve this problem. The approach consists of tracking and updating along the navigation directions of multiple axons simultaneously. The experimental results show that the proposed method can rapidly and accurately extract multiple axon centerlines and can handle complicated axon structures such as cross-over sections and overlapping objects. PMID:18336075

  18. Celsr3 and Fzd3 Organize a Pioneer Neuron Scaffold to Steer Growing Thalamocortical Axons.

    Science.gov (United States)

    Feng, Jia; Xian, Quanxiang; Guan, Tingting; Hu, Jing; Wang, Meizhi; Huang, Yuhua; So, Kwok-Fai; Evans, Sylvia M; Chai, Guoliang; Goffinet, Andre M; Qu, Yibo; Zhou, Libing

    2016-07-01

    Celsr3 and Fzd3 regulate the development of reciprocal thalamocortical projections independently of their expression in cortical or thalamic neurons. To understand this cell non autonomous mechanism further, we tested whether Celsr3 and Fzd3 could act via Isl1-positive guidepost cells. Isl1-positive cells appear in the forebrain at embryonic day (E) 9.5-E10.5 and, from E12.5, they form 2 contingents in ventral telencephalon and prethalamus. In control mice, corticothalamic axons run in the ventral telencephalic corridor in close contact with Isl1-positive cells. When Celsr3 or Fzd3 is inactivated in Isl1-expressing cells, corticofugal fibers stall and loop in the ventral telencephalic corridor of high Isl1 expression, and thalamic axons fail to cross the diencephalon-telencephalon junction (DTJ). At E12.5, before thalamic and cortical axons emerge, pioneer projections from Isl1-positive cells cross the DTJ from both sides in control but not mutant embryos. These early projections appear to act like a bridge to guide later growing thalamic axons through the DTJ. Our data suggest that Celsr3 and Fzd3 orchestrate the formation of a scaffold of pioneer neurons and their axons. This scaffold extends from prethalamus to ventral telencephalon and subcortex, and steers reciprocal corticothalamic fibers. PMID:27170656

  19. Three Novel Mutations in KIF21A Highlight the Importance of the Third Coiled-Coil Stalk Domain in the Etiology of CFEOM1

    OpenAIRE

    Gutowski Nicholas J; Pott Jan WR; Traboulsi Elias I; Yazdani Ahmad; Hunter David G; Geraghty Michael T; Lyons Christopher; Armstrong Linlea; Fredrick Douglas; Dragan Laryssa; Andrews Caroline; Chan Wai-Man; Ellard Sian; Young Elizabeth; Hanisch Frank

    2007-01-01

    Abstract Background Congenital fibrosis of the extraocular muscles types 1 and 3 (CFEOM1/CFEOM3) are autosomal dominant strabismus disorders that appear to result from maldevelopment of ocular nuclei and nerves. We previously reported that most individuals with CFEOM1 and rare individuals with CFEOM3 harbor heterozygous mutations in KIF21A. KIF21A encodes a kinesin motor involved in anterograde axonal transport, and the familial and de novo mutations reported to date predictably alter one of ...

  20. Initiation and blocking of the action potential in the axon in a weak ultrasonic field

    CERN Document Server

    Shneider, M N

    2013-01-01

    It is shown that the longitudinal standing ultrasonic wave of low intensity leads to the lateral drift and to redistribution of the transmembrane ion channels in the initial segment of the myelinated axon of a neuron. The analysis is based on the Hodgkin - Huxley model of an axon. Redistribution of the density of transmembrane sodium channels, caused by ultrasound, may reduce the threshold of the action potential, up to its spontaneous initiation. At significant redistribution of sodium channels in membrane, the zones of rarefaction of the transmembrane channels density are formed blocking the propagation of the action potential. After switching the ultrasound off, the unperturbed uniform distribution of transmembrane channels in the axon recovers due to lateral diffusion. The blocking effect of the action potential can be used in anesthesia.

  1. Cross-talk between KLF4 and STAT3 regulates axon regeneration

    Science.gov (United States)

    Qin, Song; Zou, Yuhua; Zhang, Chun-Li

    2013-10-01

    Cytokine-induced activation of signal transducer and activator of transcription 3 (STAT3) promotes the regrowth of damaged axons in the adult central nervous system (CNS). Here we show that KLF4 physically interacts with STAT3 upon cytokine-induced phosphorylation of tyrosine 705 (Y705) on STAT3. This interaction suppresses STAT3-dependent gene expression by blocking its DNA-binding activity. The deletion of KLF4 in vivo induces axon regeneration of adult retinal ganglion cells (RGCs) via Janus kinase (JAK)-STAT3 signalling. This regeneration can be greatly enhanced by exogenous cytokine treatment, or removal of an endogenous JAK-STAT3 pathway inhibitor called suppressor of cytokine signalling 3 (SOCS3). These findings reveal an unexpected cross-talk between KLF4 and activated STAT3 in the regulation of axon regeneration that might have therapeutic implications in promoting repair of injured adult CNS.

  2. Transforming Growth Factor-β Promotes Axonal Regeneration After Chronic Nerve Injury.

    Science.gov (United States)

    Sulaiman, Wale A R

    2016-04-01

    When spinal cord injury (SCI) occurs, injured cells must survive and regenerate to close gaps caused by the injury and to create functional motor units. After peripheral nerve injury, Wallerian degeneration in the distal nerve stump creates a neurotrophic and growth-supportive environment for injured neurons and axons via Schwann cells and secreted cytokines/neurotrophins. In both SCI and peripheral nerve injury, injured motor and sensory neurons must regenerate axons, eventually reaching and reinnervating target tissue (SDC Figure 1, http://links.lww.com/BRS/B116). This process is often unsuccessful after SCI, and the highly complex anatomy of branching axons and nerves in the peripheral nervous system leads to slow recovery of function, even with careful and appropriate techniques. PMID:27015069

  3. Corpus Callosum Pathology as a Potential Surrogate Marker of Cognitive Impairment in Diffuse Axonal Injury.

    Science.gov (United States)

    Ubukata, Shiho; Ueda, Keita; Sugihara, Genichi; Yassin, Walid; Aso, Toshihiko; Fukuyama, Hidenao; Murai, Toshiya

    2016-01-01

    Diffuse axonal injury is a major form of traumatic brain injury. Neuropsychological assessments and high-resolution structural MRI were conducted using T1-weighted and diffusion tensor imaging. This study included 10 patients with diffuse axonal injury (all men, mean age 30.8±10.5 years) and 12 age- and sex-matched normal control participants. Patients with diffuse axonal injury had widespread volume reductions and lower fractional anisotropy in the corpus callosum (CC) compared with controls. Furthermore, cognitive processing speed was associated with reductions in white matter volume and fractional anisotropy in the CC. These findings suggest that CC pathology may be a potential surrogate marker of the cognitive deficits in these patients. PMID:26569151

  4. Effects of laminin blended with chitosan on axon guidance on patterned substrates

    International Nuclear Information System (INIS)

    Axon guidance is a crucial consideration in the design of tissue scaffolds used to promote nerve regeneration. Here we investigate the combined use of laminin (a putative axon adhesion and guidance molecule) and chitosan (a leading candidate base material for the construction of scaffolds) for promoting axon guidance in cultured adult dorsal root ganglion (DRG) neurons. Using a dispensing-based rapid prototyping (DBRP) technique, two-dimensional grid patterns were created by dispensing chitosan or laminin-blended chitosan substrate strands oriented in orthogonal directions. In vitro experiments illustrated DRG neurites on these patterns preferentially grew upon and followed the laminin-blended chitosan pathways. These results suggest that an orientation of neurite growth can be achieved in an artificially patterned substrate by creating selectively biofunctional pathways. The DBRP technique may provide improved strategies for the use of biofunctional pathways in the design of three-dimensional scaffolds for guidance of nerve repair.

  5. A Self-Assembling Injectable Biomimetic Microenvironment Encourages Retinal Ganglion Cell Axon Extension in Vitro.

    Science.gov (United States)

    Laughter, Melissa R; Ammar, David A; Bardill, James R; Pena, Brisa; Kahook, Malik Y; Lee, David J; Park, Daewon

    2016-08-17

    Sensory-somatic nervous system neurons, such as retinal ganglion cells (RGCs), are typically thought to be incapable of regenerating. However, it is now known that these cells may be stimulated to regenerate by providing them with a growth permissive environment. We have engineered an injectable microenvironment designed to provide growth-stimulating cues for RGC culture. Upon gelation, this injectable material not only self-assembles into laminar sheets, similar to retinal organization, but also possesses a storage modulus comparable to that of retinal tissue. Primary rat RGCs were grown, stained, and imaged in this three-dimensional scaffold. We were able to show that RGCs grown in this retina-like structure exhibited characteristic long, prominent axons. In addition, RGCs showed a consistent increase in average axon length and neurite-bearing ratio over the 7 day culture period, indicating this scaffold is capable of supporting substantial RGC axon extension. PMID:27434231

  6. Nitric oxide as a putative retinal axon pathfinding and target recognition cue in Xenopus laevis

    Directory of Open Access Journals (Sweden)

    Sara Berman

    2011-01-01

    Full Text Available Nitric oxide (NO is an atypical neurotransmitter synthesized by the enzyme nitric oxide synthase (NOS during many stages of the Xenopus laevis life cycle. This research investigates whether the gas NO is involved in axon guidance, the neurodevelopmental process in which axons travel through the brain to their appropriate target locations to form functional neural circuitry. Through immunocytochemistry and direct labeling of the NO gas with a fluorescent dye, we have found that NOS expression corresponds spatiotemporally with the beginning of retinal axon innervation of the optic tectum in X. laevis. Our function-blocking studies in which NO is chemically inhibited suggest that NO may be necessary for correct pathfinding and targeting, evidenced by qualitative widening of the optic tract and aberrant target innervation.

  7. Genetic dysfunction of MT-ATP6 causes axonal Charcot-Marie-Tooth disease.

    LENUS (Irish Health Repository)

    Pitceathly, Robert D S

    2012-09-11

    Charcot-Marie-Tooth (CMT) disease is the most common inherited neuromuscular disorder, affecting 1 in 2,500 individuals. Mitochondrial DNA (mtDNA) mutations are not generally considered within the differential diagnosis of patients with uncomplicated inherited neuropathy, despite the essential requirement of ATP for axonal function. We identified the mtDNA mutation m.9185T>C in MT-ATP6, encoding the ATP6 subunit of the mitochondrial ATP synthase (OXPHOS complex V), at homoplasmic levels in a family with mitochondrial disease in whom a severe motor axonal neuropathy was a striking feature. This led us to hypothesize that mutations in the 2 mtDNA complex V subunit encoding genes, MT-ATP6 and MT-ATP8, might be an unrecognized cause of isolated axonal CMT and distal hereditary motor neuropathy (dHMN).

  8. Are Molecules Involved in Neuritogenesis and Axon Guidance Related to Autism Pathogenesis?

    Science.gov (United States)

    Bakos, Jan; Bacova, Zuzana; Grant, Stephen G; Castejon, Ana M; Ostatnikova, Daniela

    2015-09-01

    Autism spectrum disorder is a heterogeneous disease, and numerous alterations of gene expression come into play to attempt to explain potential molecular and pathophysiological causes. Abnormalities of brain development and connectivity associated with alterations in cytoskeletal rearrangement, neuritogenesis and elongation of axons and dendrites might represent or contribute to the structural basis of autism pathology. Slit/Robo signaling regulates cytoskeletal remodeling related to axonal and dendritic branching. Components of its signaling pathway (ABL and Cdc42) are suspected to be molecular bases of alterations of normal development. The present review describes the most important mechanisms underlying neuritogenesis, axon pathfinding and the role of GTPases in neurite outgrowth, with special emphasis on alterations associated with autism spectrum disorders. On the basis of analysis of publicly available microarray data, potential biomarkers of autism are discussed. PMID:25989848

  9. Retinoic acid receptor beta2 promotes functional regeneration of sensory axons in the spinal cord.

    Science.gov (United States)

    Wong, Liang-Fong; Yip, Ping K; Battaglia, Anna; Grist, John; Corcoran, Jonathan; Maden, Malcolm; Azzouz, Mimoun; Kingsman, Susan M; Kingsman, Alan J; Mazarakis, Nicholas D; McMahon, Stephen B

    2006-02-01

    The embryonic CNS readily undergoes regeneration, unlike the adult CNS, which has limited axonal repair after injury. Here we tested the hypothesis that retinoic acid receptor beta2 (RARbeta2), critical in development for neuronal growth, may enable adult neurons to grow in an inhibitory environment. Overexpression of RARbeta2 in adult rat dorsal root ganglion cultures increased intracellular levels of cyclic AMP and stimulated neurite outgrowth. Stable RARbeta2 expression in DRG neurons in vitro and in vivo enabled their axons to regenerate across the inhibitory dorsal root entry zone and project into the gray matter of the spinal cord. The regenerated neurons enhanced second-order neuronal activity in the spinal cord, and RARbeta2-treated rats showed highly significant improvement in sensorimotor tasks. These findings show that RARbeta2 induces axonal regeneration programs within injured neurons and may thus offer new therapeutic opportunities for CNS regeneration. PMID:16388307

  10. Quantitative Evaluation of Changes in the Striatal Astrocyte Axons in Simulated Parkinsonism.

    Science.gov (United States)

    Voronkov, D N; Khudoerkov, R M; Dikalova, Yu V; Sheloukhova, L I

    2016-02-01

    Three parkinsonism models using neurotoxin 6-OHDA and pesticides rotenone and paraquat were reproduced in Wistar rats and parameters of astrocyte processes in the striatum (axon number and length, area occupied by them, and axon branching pattern) detected by immunohistochemical reaction for acid glial fibrillary protein were studied by computer morphometry. By these parameters, three morphological types of astrocytes were distinguished. Two variants of changes were found in the used parkinsonism models: 1) more intense branching and even elongation of all axons and 2) reduction of small and elongation of the main remaining stems, which manifested in polarization of glial cell. Type 1 reaction was obviously associated with compensatory increase in astrocyte interaction with neurons, while type 2 reflected astrocyte response to injury and impaired glioneuronal interactions. PMID:26899846

  11. Effects of laminin blended with chitosan on axon guidance on patterned substrates

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, N; Guan, Y J; Chen, X B [Division of Biomedical Engineering, University of Saskatchewan, Saskatoon S7N 5A9 (Canada); Li, M G [Department of Mechanical Engineering, University of Saskatchewan, Saskatoon S7N 5A9 (Canada); Schreyer, D J, E-mail: niz504@mail.usask.c [Department of Anatomy and Cell Biology, Cameco MS Neuroscience Research Center, University of Saskatchewan, Saskatoon, S7K 0M7 (Canada)

    2010-12-15

    Axon guidance is a crucial consideration in the design of tissue scaffolds used to promote nerve regeneration. Here we investigate the combined use of laminin (a putative axon adhesion and guidance molecule) and chitosan (a leading candidate base material for the construction of scaffolds) for promoting axon guidance in cultured adult dorsal root ganglion (DRG) neurons. Using a dispensing-based rapid prototyping (DBRP) technique, two-dimensional grid patterns were created by dispensing chitosan or laminin-blended chitosan substrate strands oriented in orthogonal directions. In vitro experiments illustrated DRG neurites on these patterns preferentially grew upon and followed the laminin-blended chitosan pathways. These results suggest that an orientation of neurite growth can be achieved in an artificially patterned substrate by creating selectively biofunctional pathways. The DBRP technique may provide improved strategies for the use of biofunctional pathways in the design of three-dimensional scaffolds for guidance of nerve repair.

  12. Axonal lesion-induced microglial proliferation and microglial cluster formation in the mouse

    DEFF Research Database (Denmark)

    Dissing-Olesen, L; Ladeby, R; Nielsen, Helle Hvilsted; Toft-Hansen, H; Dalmau, I; Finsen, B

    2007-01-01

    Microglia are innate immune cells and form the first line of defense of the CNS. Proliferation is a key event in the activation of microglia in acute pathology, and has been extensively characterized in rats, but not in mice. In this study we investigated axonal-lesion-induced microglial prolifer......Microglia are innate immune cells and form the first line of defense of the CNS. Proliferation is a key event in the activation of microglia in acute pathology, and has been extensively characterized in rats, but not in mice. In this study we investigated axonal-lesion-induced microglial...... double staining showed that most activated, proliferating microglia occurred in multicellular clusters and co-expressed the intercellular adhesion molecule-1 and the hematopoietic stem cell marker cluster of differentiation 34. In conclusion, this study extends observations of axonal lesion...

  13. 咪唑安定和丙泊酚联用对危重患者镇静-遗忘作用的研究%Effects of combination of midazolam and propofol on anterograde amnesia in critical patients

    Institute of Scientific and Technical Information of China (English)

    许继元; 戴体俊; 李茂琴; 张舟; 卢飞; 李琳; 李家琼; 莫逊; 许艳军; 刘君

    2008-01-01

    目的 观察咪唑安定和丙泊酚联用对危重患者镇静-遗忘作用的影响.方法 选择重症加强治疗病房(ICU)行机械通气2~4 d的患者60例,随机分为丙泊酚组、咪唑安定组和咪唑安定加丙泊酚联用组,每组20例.分别于用药后1、2和3 d唤醒患者并出示不同颜色、图形、数字的卡片,于患者停用机械通气完全清醒后评估药物对其镇静-遗忘作用的影响.结果 ①丙泊酚、咪唑安定和联用组分别有70%、95%和90%的患者产生遗忘,停药30 min后患者均恢复记忆.②咪唑安定组静脉推注负荷量药物起效的时间((5.1±2.8)min]和停药清醒后拔除气管插管的时间[(2.7±0.3)h]均较丙泊酚组[(2.7±1.1)min、(0.7±0.2)h]、联用组[(3.1±1.3)min、(1.2±0.6)h]明显延长(P均<0.01);丙泊酚组和联用组药物起效时间和停药清醒后拔除气管插管时间相近,差异无统计学意义(P均>0.05).③镇静费用咪唑安定组[(1 200±112)元]和联用组[(1 300±132)元]接近,丙泊酚组[(2 100±125)元]高于咪唑安定组约75%(P<0.01).结论 丙泊酚与咪唑安定联合用药既可确保患者产生镇静-遗忘效应,减少各自的用量,降低药物不良反应,又有利于降低患者的住院费用,可能是ICU危重患者较好的镇静-遗忘治疗方案.%Objective To observe the effects of sedation with midazolam and propofol on anterograde amnesia in critical patients.Methods Sixty selected patients on mechanical ventilation in intensive care unit (ICU)were randomly divided into three subgroups(propofol,midazolam,and midazolam and propofol combination group),with 20 cases in each group.Patients who were awakened from sedation were showed with a card depicted with different colors,figures and numbers.When patients were totally conscious after weaning from mechanicaI ventilation,the influence of the different methods of sedation on anterograde amnesia in propofol,midazolam and the combination group

  14. Optically-Induced Neuronal Activity Is Sufficient to Promote Functional Motor Axon Regeneration In Vivo

    Science.gov (United States)

    Ward, Patricia J.; Jones, Laura N.; Mulligan, Amanda; Goolsby, William; Wilhelm, Jennifer C.; English, Arthur W.

    2016-01-01

    Peripheral nerve injuries are common, and functional recovery is very poor. Beyond surgical repair of the nerve, there are currently no treatment options for these patients. In experimental models of nerve injury, interventions (such as exercise and electrical stimulation) that increase neuronal activity of the injured neurons effectively enhance axon regeneration. Here, we utilized optogenetics to determine whether increased activity alone is sufficient to promote motor axon regeneration. In thy-1-ChR2/YFP transgenic mice in which a subset of motoneurons express the light-sensitive cation channel, channelrhodopsin (ChR2), we activated axons in the sciatic nerve using blue light immediately prior to transection and surgical repair of the sciatic nerve. At four weeks post-injury, direct muscle EMG responses evoked with both optical and electrical stimuli as well as the ratio of these optical/electrical evoked EMG responses were significantly greater in mice that received optical treatment. Thus, significantly more ChR2+ axons successfully re-innervated the gastrocnemius muscle in mice that received optical treatment. Sections of the gastrocnemius muscles were reacted with antibodies to Synaptic Vesicle Protein 2 (SV2) to quantify the number of re-occupied motor endplates. The number of SV2+ endplates was greater in mice that received optical treatment. The number of retrogradely-labeled motoneurons following intramuscular injection of cholera toxin subunit B (conjugated to Alexa Fluor 555) was greater in mice that received optical treatment. Thus, the acute (1 hour), one-time optical treatment resulted in robust, long-lasting effects compared to untreated animals as well as untreated axons (ChR2-). We conclude that neuronal activation is sufficient to promote motor axon regeneration, and this regenerative effect is specific to the activated neurons. PMID:27152611

  15. RNA sequence reveals mouse retinal transcriptome changes early after axonal injury.

    Science.gov (United States)

    Yasuda, Masayuki; Tanaka, Yuji; Ryu, Morin; Tsuda, Satoru; Nakazawa, Toru

    2014-01-01

    Glaucoma is an ocular disease characterized by progressive retinal ganglion cell (RGC) death caused by axonal injury. However, the underlying mechanisms involved in RGC death remain unclear. In this study, we investigated changes in the transcriptome profile following axonal injury in mice (C57BL/6) with RNA sequencing (RNA-seq) technology. The experiment group underwent an optic nerve crush (ONC) procedure to induce axonal injury in the right eye, and the control group underwent a sham procedure. Two days later, we extracted the retinas and performed RNA-seq and a pathway analysis. We identified 177 differentially expressed genes with RNA-seq, notably the endoplasmic reticulum (ER) stress-related genes Atf3, Atf4, Atf5, Chac1, Chop, Egr1 and Trb3, which were significantly upregulated. The pathway analysis revealed that ATF4 was the most significant upstream regulator. The antioxidative response-related genes Hmox1 and Srxn1, as well as the immune response-related genes C1qa, C1qb and C1qc, were also significantly upregulated. To our knowledge, this is the first reported RNA-seq investigation of the retinal transcriptome and molecular pathways in the early stages after axonal injury. Our results indicated that ER stress plays a key role under these conditions. Furthermore, the antioxidative defense and immune responses occurred concurrently in the early stages after axonal injury. We believe that our study will lead to a better understanding of and insight into the molecular mechanisms underlying RGC death after axonal injury. PMID:24676137

  16. RNA sequence reveals mouse retinal transcriptome changes early after axonal injury.

    Directory of Open Access Journals (Sweden)

    Masayuki Yasuda

    Full Text Available Glaucoma is an ocular disease characterized by progressive retinal ganglion cell (RGC death caused by axonal injury. However, the underlying mechanisms involved in RGC death remain unclear. In this study, we investigated changes in the transcriptome profile following axonal injury in mice (C57BL/6 with RNA sequencing (RNA-seq technology. The experiment group underwent an optic nerve crush (ONC procedure to induce axonal injury in the right eye, and the control group underwent a sham procedure. Two days later, we extracted the retinas and performed RNA-seq and a pathway analysis. We identified 177 differentially expressed genes with RNA-seq, notably the endoplasmic reticulum (ER stress-related genes Atf3, Atf4, Atf5, Chac1, Chop, Egr1 and Trb3, which were significantly upregulated. The pathway analysis revealed that ATF4 was the most significant upstream regulator. The antioxidative response-related genes Hmox1 and Srxn1, as well as the immune response-related genes C1qa, C1qb and C1qc, were also significantly upregulated. To our knowledge, this is the first reported RNA-seq investigation of the retinal transcriptome and molecular pathways in the early stages after axonal injury. Our results indicated that ER stress plays a key role under these conditions. Furthermore, the antioxidative defense and immune responses occurred concurrently in the early stages after axonal injury. We believe that our study will lead to a better understanding of and insight into the molecular mechanisms underlying RGC death after axonal injury.

  17. GABA increases electrical excitability in a subset of human unmyelinated peripheral axons.

    Directory of Open Access Journals (Sweden)

    Richard W Carr

    Full Text Available BACKGROUND: A proportion of small diameter primary sensory neurones innervating human skin are chemosensitive. They respond in a receptor dependent manner to chemical mediators of inflammation as well as naturally occurring algogens, thermogens and pruritogens. The neurotransmitter GABA is interesting in this respect because in animal models of neuropathic pain GABA pre-synaptically regulates nociceptive input to the spinal cord. However, the effect of GABA on human peripheral unmyelinated axons has not been established. METHODOLOGY/PRINCIPAL FINDINGS: Electrical stimulation was used to assess the effect of GABA on the electrical excitability of unmyelinated axons in isolated fascicles of human sural nerve. GABA (0.1-100 microM increased electrical excitability in a subset (ca. 40% of C-fibres in human sural nerve fascicles suggesting that axonal GABA sensitivity is selectively restricted to a sub-population of human unmyelinated axons. The effects of GABA were mediated by GABA(A receptors, being mimicked by bath application of the GABA(A agonist muscimol (0.1-30 microM while the GABA(B agonist baclofen (10-30 microM was without effect. Increases in excitability produced by GABA (10-30 microM were blocked by the GABA(A antagonists gabazine (10-20 microM, bicuculline (10-20 microM and picrotoxin (10-20 microM. CONCLUSIONS/SIGNIFICANCE: Functional GABA(A receptors are present on a subset of unmyelinated primary afferents in humans and their activation depolarizes these axons, an effect likely due to an elevated intra-axonal chloride concentration. GABA(A receptor modulation may therefore regulate segmental and peripheral components of nociception.

  18. Peripheral neuropathy in the Twitcher mouse involves the activation of axonal caspase 3

    Directory of Open Access Journals (Sweden)

    Ernesto R Bongarzone

    2011-10-01

    Full Text Available Infantile Krabbe disease results in the accumulation of lipid-raft-associated galactosylsphingosine (psychosine, demyelination, neurodegeneration and premature death. Recently, axonopathy has been depicted as a contributing factor in the progression of neurodegeneration in the Twitcher mouse, a bona fide mouse model of Krabbe disease. Analysis of the temporal-expression profile of MBP (myelin basic protein isoforms showed unexpected increases of the 14, 17 and 18.5 kDa isoforms in the sciatic nerve of 1-week-old Twitcher mice, suggesting an abnormal regulation of the myelination process during early postnatal life in this mutant. Our studies showed an elevated activation of the pro-apoptotic protease caspase 3 in sciatic nerves of 15- and 30-day-old Twitcher mice, in parallel with increasing demyelination. Interestingly, while active caspase 3 was clearly contained in peripheral axons at all ages, we found no evidence of caspase accumulation in the soma of corresponding mutant spinal cord motor neurons. Furthermore, active caspase 3 was found not only in unmyelinated axons, but also in myelinated axons of the mutant sciatic nerve. These results suggest that axonal caspase activation occurs before demyelination and following a dying-back pattern. Finally, we showed that psychosine was sufficient to activate caspase 3 in motor neuronal cells in vitro in the absence of myelinating glia. Taken together, these findings indicate that degenerating mechanisms actively and specifically mediate axonal dysfunction in Krabbe disease and support the idea that psychosine is a pathogenic sphingolipid sufficient to cause axonal defects independently of demyelination.

  19. Peripheral Nerve Diffusion Tensor Imaging: Assessment of Axon and Myelin Sheath Integrity.

    Directory of Open Access Journals (Sweden)

    A Heckel

    Full Text Available To investigate the potential of diffusion tensor imaging (DTI parameters as in-vivo biomarkers of axon and myelin sheath integrity of the median nerve in the carpal tunnel as validated by correlation with electrophysiology.MRI examinations at 3T including DTI were conducted on wrists in 30 healthy subjects. After manual segmentation of the median nerve quantitative analysis of fractional anisotropy (FA as well as axial, radial and mean diffusivity (AD, RD, and MD was carried out. Pairwise Pearson correlations with electrophysiological parameters comprising sensory nerve action potential (SNAP and compound muscle action potential (CMAP as markers of axon integrity, and distal motor latency (dml and sensory nerve conduction velocity (sNCV as markers of myelin sheath integrity were computed. The significance criterion was set at P=0.05, Bonferroni corrected for multiple comparisons.DTI parameters showed a distinct proximal-to-distal profile with FA, MD, and RD extrema coinciding in the center of the carpal tunnel. AD correlated with CMAP (r=0.50, p=0.04, Bonf. corr. but not with markers of myelin sheath integrity. RD correlated with sNCV (r=-0.53, p=0.02, Bonf. corr. but not with markers of axon integrity. FA correlated with dml (r=-0.63, p=0.002, Bonf. corr. and sNCV (r=0.68, p=0.001, Bonf. corr. but not with markers of axon integrity.AD reflects axon integrity, while RD (and FA reflect myelin sheath integrity as validated by correlation with electrophysiology. DTI parameters consistently indicate a slight decrease of structural integrity in the carpal tunnel as a physiological site of median nerve entrapment. DTI is particularly sensitive, since these findings are observed in healthy participants. Our results encourage future studies to evaluate the potential of DTI in differentiating axon from myelin sheath injury in patients with manifest peripheral neuropathies.

  20. Developmental hypothyroxinaemia induced by maternal mild iodine deficiency delays hippocampal axonal growth in the rat offspring.

    Science.gov (United States)

    Wei, W; Wang, Y; Wang, Y; Dong, J; Min, H; Song, B; Teng, W; Xi, Q; Chen, J

    2013-09-01

    Iodine is essential for the biosynthesis of thyroid hormones, including triiodothyronine and thyroxine. Thyroid hormones are important for central nervous system development. Mild maternal iodine deficiency (ID)-induced hypothyroxinaemia causes neurological deficits and mental retardation of the foetus. However, the detailed mechanism underlying these deficits is still largely unknown. Given that the growth-associated protein of 43 kDa (GAP-43), semaphorin 3A (Sema3A) and the glycogen synthase kinase 3β (GSK3β)/collapsin response mediator protein 2 (CRMP2) pathway are essential for axonal development, we hypothesise that hippocampal axonal growth-related proteins may be impaired, which may contribute to hippocampal axonal growth delay in rat offspring exposed to maternal hypothyroxinaemia. To test this hypothesis, maternal hypothyroxinaemia models were established in Wistar rats using a mild ID diet. Besides a negative control group, two maternal hypothyroidism models were created with either a severe ID diet or methimazole in the water. Our results showed that maternal hypothyroxinaemia exposure delayed offspring axonal growth on gestational day 19, postnatal day (PN) 7, PN14 and PN21. Consistent with this, the mean intensity of hippocampal CRMP2 and Tau1 immunofluorescence axonal protein was reduced in the mild ID group. Moreover, maternal hypothyroxinaemia disrupted expressions of GAP-43 and Sema3A. Furthermore, the phosphorylation of GSK3β and CRMP2 was also affected in the treated offspring, implying a potential mechanism by which hypothyroxinaemia-exposure affects neurodevelopment. Taken together, our data support the hypothesis that maternal hypothyroxinaemia may impair axonal growth of the offspring. PMID:23763342

  1. Influences of olfactory ensheathing cells transplantation on axonal regeneration in spinal cord of adult rats

    Institute of Scientific and Technical Information of China (English)

    沈慧勇; 唐勇; 吴燕峰; 陈燕涛; 程志安

    2002-01-01

    To observe whether olfactory ensheathing cells could be used to promote axonal regeneration in a spontaneously nonregenerating system. Methods: After laminectomy at the lower thoracic level, the spinal cords of adult rats were exposed and completely transected at T10. A suspension of ensheathing cells was injected into the lesion site in 12 adult rats, and control D/F-12 (1∶1 mixture of DMEM and Hams F-12) was injected in 12 adult rats. Six weeks and ten weeks after cell transplantation, the rats were evaluated by climbing test and motor evoked potentials (MEPs) monitoring. The samples were procured and studied with histologicl and immunohistochemical methods. Results: At the 6th week after cell transplantation, all the rats in both the transplanted and control groups were paraplegic and the MEPs could not be recorded. At the 10th week after cell transplantation, of 7 rats in the control group, 2 rats had muscles contraction of the lower extremities, 2 rats had hips and/or knees active movement; and 5 rats MEPs could be recorded in the hind limbs in the transplanted group (n=7). None of the rats in the control group had functional improvement and no MEPs recorded (n=7). Numerous regenerating axons were observed through the transplantation and continued to regenerate into the denervated host tract. Cell labelling using anti-Myelin Basic Protein (MBP) and anti-Nerve Growth Factor Receptor (anti-NGFR) indicated that the regenerated axons were derived from the appropriate neuronal source and that donor cells migrated into the denervated host tract. But axonal degeneration existed and regenerating axons were not observed within the spinal cords of the adult rats with only D/F-12 injection. Conclusions: The axonal regeneration in the transected adult rat spinal cord is possible after ensheathing cells transplantation.

  2. Zebrafish foxP2 zinc finger nuclease mutant has normal axon pathfinding.

    Directory of Open Access Journals (Sweden)

    Lingyan Xing

    Full Text Available foxP2, a forkhead-domain transcription factor, is critical for speech and language development in humans, but its role in the establishment of CNS connectivity is unclear. While in vitro studies have identified axon guidance molecules as targets of foxP2 regulation, and cell culture assays suggest a role for foxP2 in neurite outgrowth, in vivo studies have been lacking regarding a role for foxP2 in axon pathfinding. We used a modified zinc finger nuclease methodology to generate mutations in the zebrafish foxP2 gene. Using PCR-based high resolution melt curve analysis (HRMA of G0 founder animals, we screened and identified three mutants carrying nonsense mutations in the 2(nd coding exon: a 17 base-pair (bp deletion, an 8bp deletion, and a 4bp insertion. Sequence analysis of cDNA confirmed that these were frameshift mutations with predicted early protein truncations. Homozygous mutant fish were viable and fertile, with unchanged body morphology, and no apparent differences in CNS apoptosis, proliferation, or patterning at embryonic stages. There was a reduction in expression of the known foxP2 target gene cntnap2 that was rescued by injection of wild-type foxP2 transcript. When we examined axon pathfinding using a pan-axonal marker or transgenic lines, including a foxP2-neuron-specific enhancer, we did not observe any axon guidance errors. Our findings suggest that foxP2 is not necessary for axon pathfinding during development.

  3. Optically-Induced Neuronal Activity Is Sufficient to Promote Functional Motor Axon Regeneration In Vivo.

    Science.gov (United States)

    Ward, Patricia J; Jones, Laura N; Mulligan, Amanda; Goolsby, William; Wilhelm, Jennifer C; English, Arthur W

    2016-01-01

    Peripheral nerve injuries are common, and functional recovery is very poor. Beyond surgical repair of the nerve, there are currently no treatment options for these patients. In experimental models of nerve injury, interventions (such as exercise and electrical stimulation) that increase neuronal activity of the injured neurons effectively enhance axon regeneration. Here, we utilized optogenetics to determine whether increased activity alone is sufficient to promote motor axon regeneration. In thy-1-ChR2/YFP transgenic mice in which a subset of motoneurons express the light-sensitive cation channel, channelrhodopsin (ChR2), we activated axons in the sciatic nerve using blue light immediately prior to transection and surgical repair of the sciatic nerve. At four weeks post-injury, direct muscle EMG responses evoked with both optical and electrical stimuli as well as the ratio of these optical/electrical evoked EMG responses were significantly greater in mice that received optical treatment. Thus, significantly more ChR2+ axons successfully re-innervated the gastrocnemius muscle in mice that received optical treatment. Sections of the gastrocnemius muscles were reacted with antibodies to Synaptic Vesicle Protein 2 (SV2) to quantify the number of re-occupied motor endplates. The number of SV2+ endplates was greater in mice that received optical treatment. The number of retrogradely-labeled motoneurons following intramuscular injection of cholera toxin subunit B (conjugated to Alexa Fluor 555) was greater in mice that received optical treatment. Thus, the acute (1 hour), one-time optical treatment resulted in robust, long-lasting effects compared to untreated animals as well as untreated axons (ChR2-). We conclude that neuronal activation is sufficient to promote motor axon regeneration, and this regenerative effect is specific to the activated neurons. PMID:27152611

  4. Optically-Induced Neuronal Activity Is Sufficient to Promote Functional Motor Axon Regeneration In Vivo.

    Directory of Open Access Journals (Sweden)

    Patricia J Ward

    Full Text Available Peripheral nerve injuries are common, and functional recovery is very poor. Beyond surgical repair of the nerve, there are currently no treatment options for these patients. In experimental models of nerve injury, interventions (such as exercise and electrical stimulation that increase neuronal activity of the injured neurons effectively enhance axon regeneration. Here, we utilized optogenetics to determine whether increased activity alone is sufficient to promote motor axon regeneration. In thy-1-ChR2/YFP transgenic mice in which a subset of motoneurons express the light-sensitive cation channel, channelrhodopsin (ChR2, we activated axons in the sciatic nerve using blue light immediately prior to transection and surgical repair of the sciatic nerve. At four weeks post-injury, direct muscle EMG responses evoked with both optical and electrical stimuli as well as the ratio of these optical/electrical evoked EMG responses were significantly greater in mice that received optical treatment. Thus, significantly more ChR2+ axons successfully re-innervated the gastrocnemius muscle in mice that received optical treatment. Sections of the gastrocnemius muscles were reacted with antibodies to Synaptic Vesicle Protein 2 (SV2 to quantify the number of re-occupied motor endplates. The number of SV2+ endplates was greater in mice that received optical treatment. The number of retrogradely-labeled motoneurons following intramuscular injection of cholera toxin subunit B (conjugated to Alexa Fluor 555 was greater in mice that received optical treatment. Thus, the acute (1 hour, one-time optical treatment resulted in robust, long-lasting effects compared to untreated animals as well as untreated axons (ChR2-. We conclude that neuronal activation is sufficient to promote motor axon regeneration, and this regenerative effect is specific to the activated neurons.

  5. Ion channel density regulates switches between regular and fast spiking in soma but not in axons.

    Directory of Open Access Journals (Sweden)

    Hugo Zeberg

    2010-04-01

    Full Text Available The threshold firing frequency of a neuron is a characterizing feature of its dynamical behaviour, in turn determining its role in the oscillatory activity of the brain. Two main types of dynamics have been identified in brain neurons. Type 1 dynamics (regular spiking shows a continuous relationship between frequency and stimulation current (f-I(stim and, thus, an arbitrarily low frequency at threshold current; Type 2 (fast spiking shows a discontinuous f-I(stim relationship and a minimum threshold frequency. In a previous study of a hippocampal neuron model, we demonstrated that its dynamics could be of both Type 1 and Type 2, depending on ion channel density. In the present study we analyse the effect of varying channel density on threshold firing frequency on two well-studied axon membranes, namely the frog myelinated axon and the squid giant axon. Moreover, we analyse the hippocampal neuron model in more detail. The models are all based on voltage-clamp studies, thus comprising experimentally measurable parameters. The choice of analysing effects of channel density modifications is due to their physiological and pharmacological relevance. We show, using bifurcation analysis, that both axon models display exclusively Type 2 dynamics, independently of ion channel density. Nevertheless, both models have a region in the channel-density plane characterized by an N-shaped steady-state current-voltage relationship (a prerequisite for Type 1 dynamics and associated with this type of dynamics in the hippocampal model. In summary, our results suggest that the hippocampal soma and the two axon membranes represent two distinct kinds of membranes; membranes with a channel-density dependent switching between Type 1 and 2 dynamics, and membranes with a channel-density independent dynamics. The difference between the two membrane types suggests functional differences, compatible with a more flexible role of the soma membrane than that of the axon membrane.

  6. Assessing the axonal translocation of CeO2 and SiO2 nanoparticles in the sciatic nerve fibers of the frog: an ex vivo electrophysiological study

    Directory of Open Access Journals (Sweden)

    Kastrinaki G

    2015-11-01

    Full Text Available Georgia Kastrinaki,1,* Christos Samsouris,2,* Efstratios K Kosmidis,3 Eleni Papaioannou,1 Athanasios G Konstandopoulos,1,4 George Theophilidis2 1Aerosol and Particle Technology Laboratory (APTL, CERTH/CPERI, Thessaloniki, Greece; 2Laboratory of Animal Physiology, School of Biology, Aristotle University of Thessaloniki, Thessaloniki, Greece; 3Laboratory of Physiology, Department of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece; 4Department of Chemical Engineering, Aristotle University of Thessaloniki, Thessaloniki, Greece *These authors contributed equally to this work Abstract: The axonal translocation of two commonly used nanoparticles in medicine, namely CeO2 and SiO2, is investigated. The study was conducted on frog sciatic nerve fibers in an ex vivo preparation. Nanoparticles were applied at the proximal end of the excised nerve. A nerve stimulation protocol was followed for over 35 hours. Nerve vitality curve comparison between control and exposed nerves showed that CeO2 has no neurotoxic effect at the concentrations tested. After exposure, specimens were fixed and then screen scanned every 1 mm along their length for nanoparticle presence by means of Fourier transform infrared microscopy. We demonstrated that both nanoparticles translocate within the nerve by formation of narrow bands in the Fourier transform infrared spectrum. For the CeO2, we also demonstrated that the translocation depends on both axonal integrity and electrical activity. The speed of translocation for the two species was estimated in the range of 0.45–0.58 mm/h, close to slow axonal transportation rate. Transmission electron microscopy provided direct evidence for the presence of SiO2 in the treated nerves. Keywords: CeO2, SiO2, FTIR, nanoparticles, ex vivo electrophysiology, frog sciatic nerve, translocation

  7. Making Myelin Basic Protein -from mRNA transport to localized translation

    Directory of Open Access Journals (Sweden)

    Christina eMüller

    2013-09-01

    Full Text Available In the central nervous system (CNS of most vertebrates, oligodendrocytes enwrap neuronal axons with extensions of their plasma membrane to form the myelin sheath. Several proteins are characteristically found in myelin of which Myelin Basic Protein (MBP is the second most abundant one after Proteolipid Protein (PLP. The lack of functional MBP in rodents results in a severe hypomyelinated phenotype in the CNS demonstrating its importance for myelin synthesis. Mbp mRNA is transported from the nucleus to the plasma membrane and is translated locally at the axon-glial contact site. Axonal properties such as diameter or electrical activity influence the degree of myelination. As oligodendrocytes can myelinate many axonal segments with varying properties, localized MBP translation represents an important part of a rapid and axon-tailored synthesis machinery. MBP’s ability to compact cellular membranes may be problematic for the integrity of intracellular membranous organelles and can also explain why MBP is transported in oligodendrocytes in the form of an mRNA rather than as a protein. Here we review the recent findings regarding intracellular transport and signalling mechanisms leading to localized translation of Mbp mRNA in oligodendrocytes. More detailed insights into the MBP synthesis pathway are important for a better understanding of the myelination process and may foster the development of remyelination therapies for demyelinating diseases.

  8. Chick PTPσ regulates the targeting of retinal axons within the optic tectum

    OpenAIRE

    Rashid-Doubell, F.; McKinnell, I.; Aricescu, A R; Sajnani, G.; Stoker, A.

    2002-01-01

    Chick PTP (cPTP), also known as CRYP, is a receptor-like protein tyrosine phosphatase found on axons and growth cones. Putative ligands for cPTP are distributed within basement membranes and on glial end feet of the retina, optic nerve, and optic tectum, suggesting that cPTP signaling is occurring along the whole retinotectal pathway. We have shown previously that cPTP plays a role in supporting the retinal phase of axon outgrowth. Here we have now addressed the role of cPTP within retinal...

  9. Native chick laminin-4 containing the beta 2 chain (s-laminin) promotes motor axon growth

    OpenAIRE

    1996-01-01

    After denervation of muscle, motor axons reinnervate original synaptic sites. A recombinant fragment of the synapse specific laminin beta 2 chain (s-laminin) was reported to inhibit motor axon growth. Consequently, a specific sequence (leucine-arginine-glutamate, LRE) of the laminin beta 2 chain was proposed to act as a stop signal and to mediate specific reinnervation at the neuromuscular junction (Porter, B.E., J. Weis, and J.R. Sanes. 1995. Neuron. 14:549-559). We demonstrate here that nat...

  10. Contrast and stability of the axon diameter index from microstructure imaging with diffusion MRI

    DEFF Research Database (Denmark)

    Dyrby, Tim B; Søgaard, Lise V; Hall, Matt G;

    2013-01-01

    The ActiveAx technique fits the minimal model of white matter diffusion to diffusion MRI data acquired using optimized protocols that provide orientationally invariant indices of axon diameter and density. We investigated how limitations of the available maximal gradient strength (G(max) ) on a...... scanner influence the sensitivity to a range of axon diameters. Multishell high-angular-diffusion-imaging (HARDI) protocols for G(max) of 60, 140, 200, and 300 mT/m were optimized for the pulsed-gradient-spin-echo (PGSE) sequence. Data were acquired on a fixed monkey brain and Monte-Carlo simulations...

  11. Robust Axonal Regeneration Occurs in the Injured CAST/Ei Mouse CNS

    OpenAIRE

    Omura, T; Omura, K.; Tedeschi, A; Riva, P; Painter, MW; L. Rojas; Martin, J.; Lisi, V; Huebner, EA; Latremoliere, A; Yin, Y.; Barrett, LB; Singh, B; Lee, S.; Crisman, T

    2015-01-01

    © 2015 Elsevier Inc. Axon regeneration in the CNS requires reactivating injured neurons' intrinsic growth state and enabling growth in an inhibitory environment. Using an inbred mouse neuronal phenotypic screen, we find that CAST/Ei mouse adult dorsal root ganglion neurons extend axons more on CNS myelin than the other eight strains tested, especially when pre-injured. Injury-primed CAST/Ei neurons also regenerate markedly in the spinal cord and optic nerve more than those from C57BL/6 mice a...

  12. Fast Inactivation of Delayed Rectifier K Conductance in Squid Giant Axon and Its Cell Bodies

    OpenAIRE

    Mathes, Chris; Rosenthal, Joshua J. C.; Armstrong, Clay M.; Gilly, William F.

    1997-01-01

    Inactivation of delayed rectifier K conductance (gK) was studied in squid giant axons and in the somata of giant fiber lobe (GFL) neurons. Axon measurements were made with an axial wire voltage clamp by pulsing to VK (∼−10 mV in 50–70 mM external K) for a variable time and then assaying available gK with a strong, brief test pulse. GFL cells were studied with whole-cell patch clamp using the same prepulse procedure as well as with long depolarizations. Under our experimental conditions (12–18...

  13. Fisiopatología del síndrome de Guillain Barré axonal Physiopathology of axonal acute Guillain Barré syndrome

    Directory of Open Access Journals (Sweden)

    Juan Guillermo Montoya Ch.

    2002-02-01

    Full Text Available Se describe la fisiopatología del síndrome de Guillain Barré axonal. Se consideran especialmente cinco aspectos: 1 Agentes etiológicos, específicamente el Campylobacter jejuni. 2 Susceptibilidad genética humana. 3 Mimetismo molecular entre lipopolisacáridos y lipoproteínas. 4 Mecanismo de acción de los anticuerpos antigangliósidos y 5 Hallazgos patológicos. The physiopathology of axonal acute Guillain Barré syndrome is described. Five aspects are considered, namely: 1 Etiologic agents emphasizing on Campylobacter jejuni. 2 Human genetic predisposition. 3 Molecular mimicry between lipopolysaccharides and gangliosides. 4 Mechanisms of action of antiganglioside antibodies and, 5 Pathologic findings.

  14. The investigation of different doses of dexmedetomidine on the sedation and anterograde amnesia%不同剂量右美托咪定镇静程度及顺行性遗忘作用研究

    Institute of Scientific and Technical Information of China (English)

    胡志超; 孔莉; 许鹏程; 李颖; 董晓辉

    2015-01-01

    Objective To investigate effects of different doses of dexmedetomidine (Dex) on the sedation and anterograde amnesia in patients undergoing operation on bythus.Methods Two hundred patients,ASA Ⅰ-Ⅱ,aged 20-60,101 males and 99 females were dministered spinal-epidural anesthesia combined with Dex,undergoing operation on bythus without caesarean section.After Dex 1 μg/kg was infused intravenously 10 min (group De0 was infused intravenously the same volume of physiological saline),according to different maintenance doses of Dex,they were divided into four groups by random number table method:group De0 (group physiological saline),group De1 (0.2 μg·kg1·h-1),group De2 (0.4 μg·kg-1·h-1),group De3 (0.6 μg·kg-1·h-1).By observer's assessment of alertness/sedation(OAA/S) method,the sedation degree of the Dex was evaluated at 5 min(T1),10 min(T2),15 min (T3),20 min(T4),25 min(T5),30 min(T6),40 min(T7),50 min(T8).After 24 h of operation,the anterograde amnesia degree of Dex was assessed.Results When the OAMS scores of group De0 of sedation were all(5.00±0) at T2,T3,T4,T5,T6,T7,and T8 point,with the time of Dex infused intravenously longer and the dose of Dex increased,the OAA/S scores of group De1,group De2 and group De3[The OAMS scores of group De1 of sedation was(3.15±0.37) at T2 point,(3.26±0.44) at T3 point,(2.70±0.66) at T4 point,(2.55±0.60) at T5 point,(2.40±0.60) at T2 point,(2.05±0.76) at T7 point,(2.02±0.73) at T8 point,The OAA/S scores of group De2 of sedation was (3.10±0.64) at T2 point,(2.95±0.51) at T3 point,(2.35±0.67) at T4 point,(2.25±0.55) at T5 point,(2.10±0.45) at T6 point,(1.60±0.50) at T7 point,(1.65±0.49) at T8 point;The OAMS scores of group De3 of sedation was (3.10±0.31) at T2 point,(2.65±0.49) at T3 point,(1.95±0.39) at T4 point,(1.90±0.45) at T5 point,(1.75±0.44) at T6 point,(1.20±0.62) at T7 point,(1.25± 0.64) at T8 point] became smaller in a dose-dependent manner(P<0.05).When there were 50 cases of the no

  15. Analysis of axon tract formation in the zebrafish brain: the role of territories of gene expression and their boundaries.

    Science.gov (United States)

    Wilson, S W; Brennan, C; Macdonald, R; Brand, M; Holder, N

    1997-11-01

    Mutant analysis in the zebrafish is revealing the genes that are expressed in the early neuroepithelium and that regulate factors responsible for the guidance of commissural axons. We review work on the developing zebrafish brain illustrating the way in which territories of regulatory gene expression influence the formation and positioning of axon pathways. PMID:9321679

  16. Heteromeric Kv7.2/7.3 channels differentially regulate action potential initiation and conduction in neocortical myelinated axons

    NARCIS (Netherlands)

    Battefeld, A.; Tran, B.T.; Gavrilis, J.; Cooper, E.C.; Kole, Maarten

    2014-01-01

    Rapid energy-efficient signaling along vertebrate axons is achieved through intricate subcellular arrangements of voltage-gated ion channels and myelination. One recently appreciated example is the tight colocalization of Kv7 potassium channels and voltage-gated sodium (Nav ) channels in the axonal

  17. Peripheral motor axons of SOD1(G127X) mutant mice are susceptible to activity-dependent degeneration

    DEFF Research Database (Denmark)

    Alvarez Herrero, Susana; Calin, A; Graffmo, K S; Moldovan, M; Krarup, C

    2013-01-01

    "threshold-tracking" showed that axons recovering from RS had changes in excitability suggestive of membrane hyperpolarization, which was smaller in the SOD1(G127X) than in WT. Our data provide proof-of-principle that SOD1(G127X) axons are less resistant to activity-induced changes in ion-concentrations. It...

  18. Gas6 enhances axonal ensheathment by MBP+ membranous processes in human DRG/OL promyelinating co-cultures

    Directory of Open Access Journals (Sweden)

    Kathleen N. O’Guin

    2014-01-01

    Full Text Available The molecular requirements for human myelination are incompletely defined, and further study is needed to fully understand the cellular mechanisms involved during development and in demyelinating diseases. We have established a human co-culture model to study myelination. Our earlier observations showed that addition of human γ-carboxylated growth-arrest-specific protein 6 (Gas6 to human oligodendrocyte progenitor cell (OPC cultures enhanced their survival and maturation. Therefore, we explored the effect of Gas6 in co-cultures of enriched OPCs plated on axons of human fetal dorsal root ganglia explant. Gas6 significantly enhanced the number of myelin basic protein-positive (MBP+ oligodendrocytes with membranous processes parallel with and ensheathing axons relative to co-cultures maintained in defined medium only for 14 days. Gas6 did not increase the overall number of MBP+ oligodendrocytes/culture; however, it significantly increased the length of MBP+ oligodendrocyte processes in contact with and wrapping axons. Multiple oligodendrocytes were in contact with a single axon, and several processes from one oligodendrocyte made contact with one or multiple axons. Electron microscopy supported confocal Z-series microscopy demonstrating axonal ensheathment by MBP+ oligodendrocyte membranous processes in Gas6-treated co-cultures. Contacts between the axonal and oligodendrocyte membranes were evident and multiple wraps of oligodendrocyte membrane around the axon were visible supporting a model system in which to study events in human myelination and aspects of non-compact myelin formation.

  19. Severe degeneration of peripheral motor axons after spinal cord injury: a European multicenter study in 345 patients.

    NARCIS (Netherlands)

    Meent, H. van de; Hosman, A.J.F.; Hendriks, J.; Zwarts, M.J.; Schubert, M.

    2010-01-01

    OBJECTIVE: There are indications that perilesional and remote peripheral motor axons may degenerate after spinal cord injury (SCI). The authors investigated the magnitude and dependence on severity of SCI of this degeneration as well as whether motor axons so affected can recover. METHODS: The funct

  20. Functional recovery of regenerating motor axons is delayed in mice heterozygously deficient for the myelin protein P(0) gene

    DEFF Research Database (Denmark)

    Rosberg, Mette Romer; Alvarez, Susana; Krarup, Christian;

    2013-01-01

    whether the regeneration capacity of early symptomatic P0+/- is impaired as compared to age matched WT. Right sciatic nerves were lesioned at the thigh in 7-8 months old mice. Tibial motor axons at ankle were investigated by conventional motor conduction studies and axon excitability studies using...

  1. Functional coordination of intraflagellar transport motors.

    Science.gov (United States)

    Ou, Guangshuo; Blacque, Oliver E; Snow, Joshua J; Leroux, Michel R; Scholey, Jonathan M

    2005-07-28

    Cilia have diverse roles in motility and sensory reception, and defects in cilia function contribute to ciliary diseases such as Bardet-Biedl syndrome (BBS). Intraflagellar transport (IFT) motors assemble and maintain cilia by transporting ciliary precursors, bound to protein complexes called IFT particles, from the base of the cilium to their site of incorporation at the distal tip. In Caenorhabditis elegans, this is accomplished by two IFT motors, kinesin-II and osmotic avoidance defective (OSM)-3 kinesin, which cooperate to form two sequential anterograde IFT pathways that build distinct parts of cilia. By observing the movement of fluorescent IFT motors and IFT particles along the cilia of numerous ciliary mutants, we identified three genes whose protein products mediate the functional coordination of these motors. The BBS proteins BBS-7 and BBS-8 are required to stabilize complexes of IFT particles containing both of the IFT motors, because IFT particles in bbs-7 and bbs-8 mutants break down into two subcomplexes, IFT-A and IFT-B, which are moved separately by kinesin-II and OSM-3 kinesin, respectively. A conserved ciliary protein, DYF-1, is specifically required for OSM-3 kinesin to dock onto and move IFT particles, because OSM-3 kinesin is inactive and intact IFT particles are moved by kinesin-II alone in dyf-1 mutants. These findings implicate BBS ciliary disease proteins and an OSM-3 kinesin activator in the formation of two IFT pathways that build functional cilia. PMID:16049494

  2. Kymographic Analysis of Transport in an Individual Neuronal Sensory Cilium in Caenorhabditis elegans.

    Science.gov (United States)

    O'Hagan, Robert; Barr, Maureen M

    2016-01-01

    Intraflagellar Transport (IFT) is driven by molecular motors that travel upon microtubule-based ciliary axonemes. In the single-celled alga Chlamydomonas reinhardtii, movement of a single anterograde IFT motor, heterotrimeric kinesin-II, is required to generate two identical motile flagella. The function of this canonical anterograde IFT motor is conserved among all eukaryotes, yet multicellular organisms can generate cilia of diverse structures and functions, ranging from simple threadlike non-motile primary cilia to the elaborate cilia that make up rod and cone photoreceptors in the retina. An emerging theme is that additional molecular motors modulate the canonical IFT machinery to give rise to differing ciliary morphologies. Therefore, a complete understanding of the trafficking of ciliary receptors, as well as the biogenesis, maintenance, specialization, and function of cilia, requires the characterization of motor molecules.Here, we describe in detail our method for measuring the motility of proteins in cilia or dendrites of C. elegans male-specific CEM ciliated sensory neurons using time-lapse microscopy and kymography of green fluorescent protein (GFP)-tagged motors, receptors, and cargos. We describe, as a specific example, OSM-3::GFP puncta moving in cilia, but also include (Fig. 1) with settings that have worked well for us measuring movement of heterotrimeric kinesin-II, IFT particles, and the polycystin TRP channel PKD-2. PMID:27514919

  3. γ-diketone central neuropathy: quantitative morphometric analysis of axons in rat spinal cord white matter regions and nerve roots

    International Nuclear Information System (INIS)

    A quantitative analytical method was used to measure myelinated axon morphometric parameters (e.g., axon area, ratio of axon area/fiber area, and index of circularity) in rat nervous tissue during intoxication with 2,5-hexanedione (HD). Parameters were assessed in nerve roots (dorsal and ventral) and in ascending (gracile fasciculus and spinocerebellar tract) and descending (corticospinal and rubrospinal tracts) spinal cord white matter tracts (L4-L5) of rats intoxicated with HD at two different daily dose-rates (175 or 400 mg HD/kg/day, gavage). For each dose-rate, tissue was sampled at four neurological endpoints: unaffected, slight, moderate, and severe toxicity, as determined by gait analysis and measurements of grip strength. Results indicate that, regardless of the HD dose-rate, axon atrophy (reduced axon area) was a widespread, abundant effect that developed in concert with neurological deficits. The atrophy response occurred contemporaneously in both ascending and descending spinal tracts, which suggests that loss of caliber developed simultaneously along the proximodistal axon axis. In contrast, swollen axons were a numerically small component and were present in nerve roots and spinal tracts only during subchronic intoxication at the lower HD dose-rate (i.e., 175 mg/kg/day). Intoxication at the higher dose-rate (400 mg/kg/day) produced neurological deficits in the absence of axonal swellings. These observations in conjunction with our previous studies of HD-induced peripheral neuropathy (Toxicol. Appl. Pharmacol. 135 (1995) 58; and Toxicol. Appl. Pharmacol. 165 (2000) 127) indicate that axon atrophy, and not axonal swelling, is a primary neuropathic phenomenon

  4. Developmental Axon Stretch Stimulates Neuron Growth While Maintaining Normal Electrical Activity, Intracellular Calcium Flux, and Somatic Morphology

    Directory of Open Access Journals (Sweden)

    Joseph R Loverde

    2015-08-01

    Full Text Available Elongation of nerve fibers intuitively occurs throughout mammalian development, and is synchronized with expansion of the growing body. While most tissue systems enlarge through mitosis and differentiation, elongation of nerve fibers is remarkably unique. The emerging paradigm suggests that axons undergo stretch as contiguous tissues enlarge between the proximal and distal segments of spanning nerve fibers. While stretch is distinct from growth, tension is a known stimulus which regulates the growth of axons. Here, we hypothesized that the axon stretch-growth process may be a natural form of injury, whereby regenerative processes fortify elongating axons in order to prevent disconnection. Harnessing the live imaging capability of our axon stretch-growth bioreactors, we assessed neurons both during and following stretch for biomarkers associated with injury. Utilizing whole-cell patch clamp recording, we found no evidence of changes in spontaneous action potential activity or degradation of elicited action potentials during real-time axon stretch at strains of up to 18 % applied over 5 minutes. Unlike traumatic axonal injury, functional calcium imaging of the soma revealed no shifts in free intracellular calcium during axon stretch. Finally, the cross-sectional areas of nuclei and cytoplasms were normal, with no evidence of chromatolysis following week-long stretch-growth limited to the lower of 25 % strain or 3 mm total daily stretch. The neuronal growth cascade coupled to stretch was concluded to be independent of the changes in membrane potential, action potential generation, or calcium flux associated with traumatic injury. While axon stretch-growth is likely to share overlap with regenerative processes, we conclude that developmental stretch is a distinct stimulus from traumatic axon injury.

  5. Subcellular localization of the antidepressant-sensitive norepinephrine transporter

    Directory of Open Access Journals (Sweden)

    Winder Danny G

    2009-06-01

    Full Text Available Abstract Background Reuptake of synaptic norepinephrine (NE via the antidepressant-sensitive NE transporter (NET supports efficient noradrenergic signaling and presynaptic NE homeostasis. Limited, and somewhat contradictory, information currently describes the axonal transport and localization of NET in neurons. Results We elucidate NET localization in brain and superior cervical ganglion (SCG neurons, aided by a new NET monoclonal antibody, subcellular immunoisolation techniques and quantitative immunofluorescence approaches. We present evidence that axonal NET extensively colocalizes with syntaxin 1A, and to a limited degree with SCAMP2 and synaptophysin. Intracellular NET in SCG axons and boutons also quantitatively segregates from the vesicular monoamine transporter 2 (VMAT2, findings corroborated by organelle isolation studies. At the surface of SCG boutons, NET resides in both lipid raft and non-lipid raft subdomains and colocalizes with syntaxin 1A. Conclusion Our findings support the hypothesis that SCG NET is segregated prior to transport from the cell body from proteins comprising large dense core vesicles. Once localized to presynaptic boutons, NET does not recycle via VMAT2-positive, small dense core vesicles. Finally, once NET reaches presynaptic plasma membranes, the transporter localizes to syntaxin 1A-rich plasma membrane domains, with a portion found in cholera toxin-demarcated lipid rafts. Our findings indicate that activity-dependent insertion of NET into the SCG plasma membrane derives from vesicles distinct from those that deliver NE. Moreover, NET is localized in presynaptic membranes in a manner that can take advantage of regulatory processes targeting lipid raft subdomains.

  6. MicroRNA 146a locally mediates distal axonal growth of dorsal root ganglia neurons under high glucose and sildenafil conditions.

    Science.gov (United States)

    Jia, Longfei; Wang, Lei; Chopp, Michael; Zhang, Yi; Szalad, Alexandra; Zhang, Zheng Gang

    2016-08-01

    Axonal loss contributes to induction of diabetic peripheral neuropathy. Sildenafil, a phosphodiesterase type 5 inhibitor, ameliorates neurological dysfunction in diabetic peripheral neuropathy. However, the direct effect of high glucose and sildenafil on axonal growth has not been extensively investigated. Using rat primary dorsal root ganglia (DRG) neurons cultured in a microfluidic chamber, we investigated the effect of axonal application of high glucose and sildenafil on distal axonal growth. We found that axonal, but not cell body, application of high glucose locally inhibited distal axonal growth. However, axonal application of sildenafil overcame high glucose-reduced axonal growth. Quantitative real-time RT-PCR (qRT-PCR) and Western blot analysis of distal axonal samples revealed that high glucose reduced axonal miR-146a levels and substantially increased miR-146a target genes, IRAK1 and TRAF6 in the axon. In contrast, sildenafil significantly reversed high glucose-reduced miR-146a levels and high glucose-increased IRAK1 and TRAF6. Gain- and loss-of function of miR-146a in DRG neurons revealed that miR-146a mediated the local effect of high glucose on the distal axonal growth. These in vitro data provide new insights into molecular mechanisms of diabetic peripheral neuropathy. PMID:27167084

  7. Active diffusion and microtubule-based transport oppose myosin forces to position organelles in cells

    Science.gov (United States)

    Lin, Congping; Schuster, Martin; Guimaraes, Sofia Cunha; Ashwin, Peter; Schrader, Michael; Metz, Jeremy; Hacker, Christian; Gurr, Sarah Jane; Steinberg, Gero

    2016-06-01

    Even distribution of peroxisomes (POs) and lipid droplets (LDs) is critical to their role in lipid and reactive oxygen species homeostasis. How even distribution is achieved remains elusive, but diffusive motion and directed motility may play a role. Here we show that in the fungus Ustilago maydis ~95% of POs and LDs undergo diffusive motions. These movements require ATP and involve bidirectional early endosome motility, indicating that microtubule-associated membrane trafficking enhances diffusion of organelles. When early endosome transport is abolished, POs and LDs drift slowly towards the growing cell end. This pole-ward drift is facilitated by anterograde delivery of secretory cargo to the cell tip by myosin-5. Modelling reveals that microtubule-based directed transport and active diffusion support distribution, mobility and mixing of POs. In mammalian COS-7 cells, microtubules and F-actin also counteract each other to distribute POs. This highlights the importance of opposing cytoskeletal forces in organelle positioning in eukaryotes.

  8. Active diffusion and microtubule-based transport oppose myosin forces to position organelles in cells.

    Science.gov (United States)

    Lin, Congping; Schuster, Martin; Guimaraes, Sofia Cunha; Ashwin, Peter; Schrader, Michael; Metz, Jeremy; Hacker, Christian; Gurr, Sarah Jane; Steinberg, Gero

    2016-01-01

    Even distribution of peroxisomes (POs) and lipid droplets (LDs) is critical to their role in lipid and reactive oxygen species homeostasis. How even distribution is achieved remains elusive, but diffusive motion and directed motility may play a role. Here we show that in the fungus Ustilago maydis ∼95% of POs and LDs undergo diffusive motions. These movements require ATP and involve bidirectional early endosome motility, indicating that microtubule-associated membrane trafficking enhances diffusion of organelles. When early endosome transport is abolished, POs and LDs drift slowly towards the growing cell end. This pole-ward drift is facilitated by anterograde delivery of secretory cargo to the cell tip by myosin-5. Modelling reveals that microtubule-based directed transport and active diffusion support distribution, mobility and mixing of POs. In mammalian COS-7 cells, microtubules and F-actin also counteract each other to distribute POs. This highlights the importance of opposing cytoskeletal forces in organelle positioning in eukaryotes. PMID:27251117

  9. Changes in the axonal conduction velocity of pyramidal tract neurons in the aged cat.

    Science.gov (United States)

    Xi, M C; Liu, R H; Engelhardt, J K; Morales, F R; Chase, M H

    1999-01-01

    The present study was undertaken to determine whether age-dependent changes in axonal conduction velocity occur in pyramidal tract neurons. A total of 260 and 254 pyramidal tract neurons were recorded extracellularly in the motor cortex of adult control and aged cats, respectively. These cells were activated antidromically by electrical stimulation of the medullary pyramidal tract. Fast- and slow-conducting neurons were identified according to their axonal conduction velocity in both control and aged cats. While 51% of pyramidal tract neurons recorded in the control cats were fast conducting (conduction velocity greater than 20 m/s), only 26% of pyramidal tract neurons in the aged cats were fast conducting. There was a 43% decrease in the median conduction velocity for the entire population of pyramidal tract neurons in aged cats when compared with that of pyramidal tract neurons in the control cats (P cats. However, the regression slope was significantly reduced in aged cats. This reduction was due to the appearance of a group of pyramidal tract neurons with relatively shorter spike durations but slower axonal conduction velocities in the aged cat. Sample intracellular data confirmed the above results. These observations form the basis for the following conclusions: (i) there is a decrease in median conduction velocity of pyramidal tract neurons in aged cats; (ii) the reduction in the axonal conduction velocity of pyramidal tract neurons in aged cats is due, in part, to fibers that previously belonged to the fast-conducting group and now conduct at slower velocity. PMID:10392844

  10. The Actin-Binding Protein α-Adducin Is Required for Maintaining Axon Diameter

    Directory of Open Access Journals (Sweden)

    Sérgio Carvalho Leite

    2016-04-01

    Full Text Available The actin-binding protein adducin was recently identified as a component of the neuronal subcortical cytoskeleton. Here, we analyzed mice lacking adducin to uncover the function of this protein in actin rings. α-adducin knockout mice presented progressive axon enlargement in the spinal cord and optic and sciatic nerves, followed by axon degeneration and loss. Using stimulated emission depletion super-resolution microscopy, we show that a periodic subcortical actin cytoskeleton is assembled in every neuron type inspected including retinal ganglion cells and dorsal root ganglia neurons. In neurons devoid of adducin, the actin ring diameter increased, although the inter-ring periodicity was maintained. In vitro, the actin ring diameter adjusted as axons grew, suggesting the lattice is dynamic. Our data support a model in which adducin activity is not essential for actin ring assembly and periodicity but is necessary to control the diameter of both actin rings and axons and actin filament growth within rings.

  11. Dimethyl Fumarate Ameliorates Lewis Rat Experimental Autoimmune Neuritis and Mediates Axonal Protection.

    Directory of Open Access Journals (Sweden)

    Kalliopi Pitarokoili

    Full Text Available Dimethyl fumarate is an immunomodulatory and neuroprotective drug, approved recently for the treatment of relapsing-remitting multiple sclerosis. In view of the limited therapeutic options for human acute and chronic polyneuritis, we used the animal model of experimental autoimmune neuritis in the Lewis rat to study the effects of dimethyl fumarate on autoimmune inflammation and neuroprotection in the peripheral nervous system.Experimental autoimmune neuritis was induced by immunization with the neuritogenic peptide (amino acids 53-78 of P2 myelin protein. Preventive treatment with dimethyl fumarate given at 45 mg/kg twice daily by oral gavage significantly ameliorated clinical neuritis by reducing demyelination and axonal degeneration in the nerve conduction studies. Histology revealed a significantly lower degree of inflammatory infiltrates in the sciatic nerves. In addition, we detected a reduction of early signs of axonal degeneration through a reduction of amyloid precursor protein expressed in axons of the peripheral nerves. This reduction correlated with an increase of nuclear factor (erythroid derived 2-related factor 2 positive axons, supporting the neuroprotective potential of dimethyl fumarate. Furthermore, nuclear factor (erythroid derived 2-related factor 2 expression in Schwann cells was only rarely detected and there was no increase of Schwann cells death during EAN.We conclude that immunomodulatory and neuroprotective dimethyl fumarate may represent an innovative therapeutic option in human autoimmune neuropathies.

  12. Evidence for Dysregulation of Axonal Growth and Guidance in the Etiology of ASD

    Directory of Open Access Journals (Sweden)

    Kathryn eMcFadden

    2013-10-01

    Full Text Available Current theories concerning the cause of autism spectrum disorders (ASDs have converged on the concept of abnormal development of brain connectivity. This concept is supported by accumulating evidence from functional imaging, DTI, and high definition fiber tracking (HDFT studies which suggest altered microstructure in the axonal tracts connecting cortical areas may underly many of the cognitive manifestations of ASD. Additionally, large-scale genomic studies implicate numerous gene candidates known or suspected to mediate neuritic outgrowth and axonal guidance in fetal and perinatal life. Neuropathological observations in postmortem ASD brain samples further support this model and include subtle disturbances of cortical lamination and subcortical axonal morphology. Of note is the relatively common finding of poor differentiation of the gray-white junction associated with an excess superficial white matter or interstitial neurons (INs. INs are thought to be remnants of the fetal subplate, a transient structure which plays a key role in the guidance and morphogenesis of thalamocortical and cortico-cortical connections and the organization of cortical columnar architecture. While not discounting the importance of synaptic dysfunction in the etiology of ASD, this paper will briefly review the cortical abnormalities and genetic evidence supporting a model of dysregulated axonal growth and guidance as key developmental processes underlying the clinical manifestations of ASD.

  13. Numerical simulation of solitons in the nerve axon using finite differences

    OpenAIRE

    Werpers, Jonatan

    2014-01-01

    A High-order accurate finite difference scheme is derived for a non-linear soliton model of nerve signal propagation in axons. Boundary conditions yielding well-posed problems are suggested and included in the scheme using a penalty technique. Stability is shown using the summation-by-parts framework for a frozen parameter version of the non-linear problem.

  14. Differential expression of metabotropic glutamate and GABAB receptors at neocortical glutamatergic and GABAergic axon terminals

    Directory of Open Access Journals (Sweden)

    Tiziana Bonifacino

    2015-09-01

    Overall, these findings indicate that mGluR1α, mGluR5, mGluR2/3, mGluR7 and GABAB1 expression differ significantly between glutamatergic and GABAergic axon terminals, and that the robust expression of heteroreceptors may contribute to the homeostatic regulation of the balance between excitation and inhibition.

  15. Axonal voltage-gated ion channels as pharmacological targets for pain

    DEFF Research Database (Denmark)

    Moldovan, Mihai; Alvarez, Susana; Romer Rosberg, Mette;

    2013-01-01

    Upon peripheral nerve injury (caused by trauma or disease process) axons of the dorsal root ganglion (DRG) somatosensory neurons have the ability to sprout and regrow/remyelinate to reinnervate distant target tissue or form a tangled scar mass called a neuroma. This regenerative response can become...

  16. Myelin loss and axonal ion channel adaptations associated with gray matter neuronal hyperexcitability

    NARCIS (Netherlands)

    Hamada, Mustafa S; Kole, Maarten H P

    2015-01-01

    Myelination and voltage-gated ion channel clustering at the nodes of Ranvier are essential for the rapid saltatory conduction of action potentials. Whether myelination influences the structural organization of the axon initial segment (AIS) and action potential initiation is poorly understood. Using

  17. Depth-sensing nano-indentation on a myelinated axon at various stages

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Wei-Chin; Liao, Jiunn-Der [Department of Materials Science and Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Lin, Chou-Ching K [Department of Neurology, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Ju, Ming-Shaung, E-mail: jdliao@mail.ncku.edu.tw [Department of Mechanical Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China)

    2011-07-08

    A nano-mechanical characterization of a multi-layered myelin sheath structure, which enfolds an axon and plays a critical role in the transmission of nerve impulses, is conducted. Schwann cells co-cultured in vitro with PC12 cells for various co-culture times are differentiated to form a myelinated axon, which is then observed using a transmission electron microscope. Three major myelination stages, with distinct structural characteristics and thicknesses around the axon, can be produced by varying the co-culture time. A dynamic contact module and continuous depth-sensing nano-indentation are used on the myelinated structure to obtain the load-on-sample versus measured displacement curve of a multi-layered myelin sheath, which is used to determine the work required for the nano-indentation tip to penetrate the myelin sheath. By analyzing the harmonic contact stiffness versus the measured displacement profile, the results can be used to estimate the three stages of the multi-layered structure on a myelinated axon. The method can also be used to evaluate the development stages of myelination or demyelination during nerve regeneration.

  18. Depth-sensing nano-indentation on a myelinated axon at various stages

    Science.gov (United States)

    Huang, Wei-Chin; Liao, Jiunn-Der; Lin, Chou-Ching K.; Ju, Ming-Shaung

    2011-07-01

    A nano-mechanical characterization of a multi-layered myelin sheath structure, which enfolds an axon and plays a critical role in the transmission of nerve impulses, is conducted. Schwann cells co-cultured in vitro with PC12 cells for various co-culture times are differentiated to form a myelinated axon, which is then observed using a transmission electron microscope. Three major myelination stages, with distinct structural characteristics and thicknesses around the axon, can be produced by varying the co-culture time. A dynamic contact module and continuous depth-sensing nano-indentation are used on the myelinated structure to obtain the load-on-sample versus measured displacement curve of a multi-layered myelin sheath, which is used to determine the work required for the nano-indentation tip to penetrate the myelin sheath. By analyzing the harmonic contact stiffness versus the measured displacement profile, the results can be used to estimate the three stages of the multi-layered structure on a myelinated axon. The method can also be used to evaluate the development stages of myelination or demyelination during nerve regeneration.

  19. Uncoupling nicotine mediated motoneuron axonal pathfinding errors and muscle degeneration in zebrafish

    International Nuclear Information System (INIS)

    Zebrafish embryos offer a unique opportunity to investigate the mechanisms by which nicotine exposure impacts early vertebrate development. Embryos exposed to nicotine become functionally paralyzed by 42 hpf suggesting that the neuromuscular system is compromised in exposed embryos. We previously demonstrated that secondary spinal motoneurons in nicotine-exposed embryos were delayed in development and that their axons made pathfinding errors (Svoboda, K.R., Vijayaraghaven, S., Tanguay, R.L., 2002. Nicotinic receptors mediate changes in spinal motoneuron development and axonal pathfinding in embryonic zebrafish exposed to nicotine. J. Neurosci. 22, 10731-10741). In that study, we did not consider the potential role that altered skeletal muscle development caused by nicotine exposure could play in contributing to the errors in spinal motoneuron axon pathfinding. In this study, we show that an alteration in skeletal muscle development occurs in tandem with alterations in spinal motoneuron development upon exposure to nicotine. The alteration in the muscle involves the binding of nicotine to the muscle-specific AChRs. The nicotine-induced alteration in muscle development does not occur in the zebrafish mutant (sofa potato, [sop]), which lacks muscle-specific AChRs. Even though muscle development is unaffected by nicotine exposure in sop mutants, motoneuron axonal pathfinding errors still occur in these mutants, indicating a direct effect of nicotine exposure on nervous system development.

  20. Effect of Long-Term Cannabis Use on Axonal Fibre Connectivity

    Science.gov (United States)

    Zalesky, Andrew; Solowij, Nadia; Yucel, Murat; Lubman, Dan I.; Takagi, Michael; Harding, Ian H.; Lorenzetti, Valentina; Wang, Ruopeng; Searle, Karissa; Pantelis, Christos; Seal, Marc

    2012-01-01

    Cannabis use typically begins during adolescence and early adulthood, a period when cannabinoid receptors are still abundant in white matter pathways across the brain. However, few studies to date have explored the impact of regular cannabis use on white matter structure, with no previous studies examining its impact on axonal connectivity. The…

  1. A phantom axon setup for validating models of action potential recordings.

    Science.gov (United States)

    Rossel, Olivier; Soulier, Fabien; Bernard, Serge; Guiraud, David; Cathébras, Guy

    2016-08-01

    Electrode designs and strategies for electroneurogram recordings are often tested first by computer simulations and then by animal models, but they are rarely implanted for long-term evaluation in humans. The models show that the amplitude of the potential at the surface of an axon is higher in front of the nodes of Ranvier than at the internodes; however, this has not been investigated through in vivo measurements. An original experimental method is presented to emulate a single fiber action potential in an infinite conductive volume, allowing the potential of an axon to be recorded at both the nodes of Ranvier and the internodes, for a wide range of electrode-to-fiber radial distances. The paper particularly investigates the differences in the action potential amplitude along the longitudinal axis of an axon. At a short radial distance, the action potential amplitude measured in front of a node of Ranvier is two times larger than in the middle of two nodes. Moreover, farther from the phantom axon, the measured action potential amplitude is almost constant along the longitudinal axis. The results of this new method confirm the computer simulations, with a correlation of 97.6 %. PMID:27016364

  2. Motor axon loss is associated with hand dysfunction in Charcot-Marie-Tooth disease 1a.

    NARCIS (Netherlands)

    Videler, A.J.; Dijk, J.P. van; Beelen, A.; Visser, M. de; Nollet, F.; Schaik, I.N. van

    2008-01-01

    BACKGROUND: Charcot Marie Tooth type 1a (CMT1a) is a primarily demyelinating neuropathy, characterized by slowly progressive muscle weakness, atrophy, and sensory loss, and is most pronounced in both feet and hands. There is increasing evidence that muscle weakness is determined by motor axonal dysf

  3. Pathogenesis of axonal dystrophy and demyelination in alphaA-crystallin-expressing transgenic mice.

    NARCIS (Netherlands)

    Rijk, A. van; Sweers, M.A.; Merkx, G.F.M.; Lammens, M.M.Y.; Bloemendal, H.

    2003-01-01

    We recently described a transgenic mouse strain overexpressing hamster alphaA-crystallin, a small heat shock protein, under direction of the hamster vimentin promoter. As a result myelin was degraded and axonal dystrophy in both central nervous system (especially spinal cord) and peripheral nervous

  4. A new model to produce sagittal plane rotational induced diffuse axonal injuries

    Directory of Open Access Journals (Sweden)

    MartenRisling

    2011-06-01

    Numerous combinations of trauma levels, post-trauma survival times, brain and serum retrieval and tissue preparation techniques were adopted to characterise this new model. The trauma caused subdural bleedings in animals exposed to severe trauma. Staining brain tissue with β-Amyloid Precursor Protein antibodies and FD Neurosilver that detect degenerating axons revealed wide spread axonal injuries (AI in the corpus callosum, the border between the corpus callosum and cortex and in tracts in the brain stem. The observed AI:s were apparent only when the rotational acceleration level was moderate and above. On the contrary, only limited signs of contusion injuries were observed following trauma. S100 serum analyses indicate that blood vessel and glia cell injuries occur following moderate levels of trauma despite the absence of obvious BBB injuries. We conclude that this rotational trauma model is capable of producing graded axonal injury, is repeatable and produces limited other types of traumatic brain injuries (TBI and as such is useful in the study of injury biomechanics, diagnostics and treatment strategies following diffuse axonal injury (DAI.

  5. Axon regeneration impediment:the role of paired immunoglobulin-like receptor B

    Institute of Scientific and Technical Information of China (English)

    Jing Liu; Yan Wang; Wei Fu

    2015-01-01

    Regenerative capacity is weak after central nervous system injury because of the absence of an enhancing microenvironment and presence of an inhibitory microenvironment for neuronal and axonal repair. In addition to the Nogo receptor (NgR), the paired immunoglobulin-like receptor B (PirB) is a recently discovered coreceptor of Nogo, myelin-associated glycoprotein, and myelin oligodendrocyte glycoprotein. Concurrent blocking of NgR and PirB almost completely elim-inates the inhibitory effect of myelin-associated inhibitory molecules on axonal regeneration. PirB participates in a key pathological process of the nervous system, speciifcally axonal regener-ation inhibition. PirB is an inhibitory receptor similar to NgR, but their effects are not identical. This study summarizes the structure, distribution, relationship with common nervous system diseases, and known mechanisms of PirB, and concludes that PirB is also distributed in cells of the immune and hematopoietic systems. Further investigations are needed to determine if im-munomodulation and blood cell migration involve inhibition of axonal regeneration.

  6. Nerve growth factor released from a novel PLGA nerve conduit can improve axon growth

    Science.gov (United States)

    Lin, Keng-Min; Shea, Jill; Gale, Bruce K.; Sant, Himanshu; Larrabee, Patti; Agarwal, Jay

    2016-04-01

    Nerve injury can occur due to penetrating wounds, compression, traumatic stretch, and cold exposure. Despite prompt repair, outcomes are dismal. In an attempt to help resolve this challenge, in this work, a poly-lactic-co-glycolic acid (PLGA) nerve conduit with associated biodegradable drug reservoir was designed, fabricated, and tested. Unlike current nerve conduits, this device is capable of fitting various clinical scenarios by delivering different drugs without reengineering the whole system. To demonstrate the potential of this device for nerve repair, a series of experiments were performed using nerve growth factor (NGF). First, an NGF dosage curve was developed to determine the minimum NGF concentration for optimal axonal outgrowth on chick dorsal root ganglia (DRG) cells. Next, PLGA devices loaded with NGF were evaluated for sustained drug release and axon growth enhancement with the released drug. A 20 d in vitro release test was conducted and the nerve conduit showed the ability to meet and maintain the minimum NGF requirement determined previously. Bioactivity assays of the released NGF showed that drug released from the device between the 15th and 20th day could still promote axon growth (76.6-95.7 μm) in chick DRG cells, which is in the range of maximum growth. These novel drug delivery conduits show the ability to deliver NGF at a dosage that efficiently promotes ex vivo axon growth and have the potential for in vivo application to help bridge peripheral nerve gaps.

  7. Short Stop provides an essential link between F-actin and microtubules during axon extension.

    Science.gov (United States)

    Lee, Seungbok; Kolodziej, Peter A

    2002-03-01

    Coordination of F-actin and microtubule dynamics is important for cellular motility and morphogenesis, but little is known about underlying mechanisms. short stop (shot) encodes an evolutionarily conserved, neuronally expressed family of rod-like proteins required for sensory and motor axon extension in Drosophila melanogaster. We identify Shot isoforms that contain N-terminal F-actin and C-terminal microtubule-binding domains, and that crosslink F-actin and microtubules in cultured cells. The F-actin- and microtubule-binding domains of Shot are required in the same molecule for axon extension, though the length of the connecting rod domain can be dramatically reduced without affecting activity. Shot therefore functions as a cytoskeletal crosslinker in axon extension, rather than mediating independent interactions with F-actin and microtubules. A Ca(2+)-binding motif located adjacent to the microtubule-binding domain is also required for axon extension, suggesting that intracellular Ca(2+) release may regulate Shot activity. These results suggest that Shot coordinates regulated interactions between F-actin and microtubules that are crucial for neuronal morphogenesis. PMID:11874915

  8. Morphological relationship between axon and dendritic arborizations as revealed by Minkowski functionals

    OpenAIRE

    Costa, Luciano da Fontoura; Barbosa, Marconi Soares

    2007-01-01

    The spatial structure of the axonal and dendritic arborizations is closely related to the functionality of specific neurons or neuronal subsystems. The present work describes how multiscale Minkowski functionals can be used in order to characterize and compare the spatial organization of these two types of arborizations. The discrimination potential of the method is illustrated with respect to three classes of cortical neurons.

  9. Nerve growth factor released from a novel PLGA nerve conduit can improve axon growth

    International Nuclear Information System (INIS)

    Nerve injury can occur due to penetrating wounds, compression, traumatic stretch, and cold exposure. Despite prompt repair, outcomes are dismal. In an attempt to help resolve this challenge, in this work, a poly-lactic-co-glycolic acid (PLGA) nerve conduit with associated biodegradable drug reservoir was designed, fabricated, and tested. Unlike current nerve conduits, this device is capable of fitting various clinical scenarios by delivering different drugs without reengineering the whole system. To demonstrate the potential of this device for nerve repair, a series of experiments were performed using nerve growth factor (NGF). First, an NGF dosage curve was developed to determine the minimum NGF concentration for optimal axonal outgrowth on chick dorsal root ganglia (DRG) cells. Next, PLGA devices loaded with NGF were evaluated for sustained drug release and axon growth enhancement with the released drug. A 20 d in vitro release test was conducted and the nerve conduit showed the ability to meet and maintain the minimum NGF requirement determined previously. Bioactivity assays of the released NGF showed that drug released from the device between the 15th and 20th day could still promote axon growth (76.6–95.7 μm) in chick DRG cells, which is in the range of maximum growth. These novel drug delivery conduits show the ability to deliver NGF at a dosage that efficiently promotes ex vivo axon growth and have the potential for in vivo application to help bridge peripheral nerve gaps. (paper)

  10. A regenerative microchannel neural interface for recording from and stimulating peripheral axons in vivo.

    Science.gov (United States)

    FitzGerald, James J; Lago, Natalia; Benmerah, Samia; Serra, Jordi; Watling, Christopher P; Cameron, Ruth E; Tarte, Edward; Lacour, Stéphanie P; McMahon, Stephen B; Fawcett, James W

    2012-02-01

    Neural interfaces are implanted devices that couple the nervous system to electronic circuitry. They are intended for long term use to control assistive technologies such as muscle stimulators or prosthetics that compensate for loss of function due to injury. Here we present a novel design of interface for peripheral nerves. Recording from axons is complicated by the small size of extracellular potentials and the concentration of current flow at nodes of Ranvier. Confining axons to microchannels of ~100 µm diameter produces amplified potentials that are independent of node position. After implantation of microchannel arrays into rat sciatic nerve, axons regenerated through the channels forming 'mini-fascicles', each typically containing ~100 myelinated fibres and one or more blood vessels. Regenerated motor axons reconnected to distal muscles, as demonstrated by the recovery of an electromyogram and partial prevention of muscle atrophy. Efferent motor potentials and afferent signals evoked by muscle stretch or cutaneous stimulation were easily recorded from the mini-fascicles and were in the range of 35-170 µV. Individual motor units in distal musculature were activated from channels using stimulus currents in the microampere range. Microchannel interfaces are a potential solution for applications such as prosthetic limb control or enhancing recovery after nerve injury. PMID:22258138

  11. Chemokine expression by glial cells directs leukocytes to sites of axonal injury in the CNS

    DEFF Research Database (Denmark)

    Babcock, Alicia A; Kuziel, William A; Rivest, Serge;

    2003-01-01

    Innate responses in the CNS are critical to first line defense against infection and injury. Leukocytes migrate to inflammatory sites in response to chemokines. We studied leukocyte migration and glial chemokine expression within the denervated hippocampus in response to axonal injury caused by e...

  12. Computational modeling reveals optimal strategy for kinase transport by microtubules to nerve terminals.

    Science.gov (United States)

    Koon, Yen Ling; Koh, Cheng Gee; Chiam, Keng-Hwee

    2014-01-01

    Intracellular transport of proteins by motors along cytoskeletal filaments is crucial to the proper functioning of many eukaryotic cells. Since most proteins are synthesized at the cell body, mechanisms are required to deliver them to the growing periphery. In this article, we use computational modeling to study the strategies of protein transport in the context of JNK (c-JUN NH2-terminal kinase) transport along microtubules to the terminals of neuronal cells. One such strategy for protein transport is for the proteins of the JNK signaling cascade to bind to scaffolds, and to have the whole protein-scaffold cargo transported by kinesin motors along microtubules. We show how this strategy outperforms protein transport by diffusion alone, using metrics such as signaling rate and signal amplification. We find that there exists a range of scaffold concentrations for which JNK transport is optimal. Increase in scaffold concentration increases signaling rate and signal amplification but an excess of scaffolds results in the dilution of reactants. Similarly, there exists a range of kinesin motor speeds for which JNK transport is optimal. Signaling rate and signal amplification increases with kinesin motor speed until the speed of motor translocation becomes faster than kinase/scaffold-motor binding. Finally, we suggest experiments that can be performed to validate whether, in physiological conditions, neuronal cells do indeed adopt such an optimal strategy. Understanding cytoskeletal-assisted protein transport is crucial since axonal and cell body accumulation of organelles and proteins is a histological feature in many human neurodegenerative diseases. In this paper, we have shown that axonal transport performance changes with altered transport component concentrations and transport speeds wherein these aspects can be modulated to improve axonal efficiency and prevent or slowdown axonal deterioration. PMID:24691408

  13. Influence of cryopreserved olfactory ensheathing cells transplantation on axonal regeneration in spinal cord of adult rats

    Institute of Scientific and Technical Information of China (English)

    沈慧勇; 殷德振; 唐勇; 吴燕峰; 程志安; 杨睿; 黄霖

    2004-01-01

    Objective: To observe the effects of cryopreserved olfactory ensheathing cells (OECs) transplantation on axonal regeneration and functional recovery following spinal cord injury in adult rats.Methods: Twenty-four rats were divided into experimental and control groups, each group having 12 rats. The spinal cord injury was established by transecting the spinal cord at T10 level with microsurgery scissors.OECs were purified from SD rat olfactory bulb and cultured in DMEM ( Dulbecco's minimum essential medium) and cryopreserved (-120℃) for two weeks.OECs suspension[(1-1.4)×105/ul] was transplanted into transected spinal cord, while the DMEM solution was injected instead in the control group. At 6 and 12 weeks after transplantation, the rats were evaluated with climbing test and MEP ( moter evoked potentials) monitoring. The samples of spinal cord were procured and studied with histological and immunohisto chemical stainings.Results: At 6 weeks after transplantation, all of the rats in both transplanted and control groups were paraplegic, and MEPs could not be recorded. Morphology of transplanted OECs was normal, and OECs were interfused with host well. Axons could regrow into gap tissue between the spinal cords. Both OECs and regrown axons were immunoreactive for MBP. No regrown axons were found in the control group. At 12 weeks after transplantation, 2 rats (2/7) had lower extremities muscle contraction, 2 rats (2/7) had hip and/or knee active movement, and MEP of 5 rats (5/7) could be recorded in the calf in the transplantation group. None of the rats (7/ 7) in the control group had functional improvement, and none had MEPs recorded. In the transplanted group,histological and immunohistochemical methods showed the number of transplanted OECs reduced and some regrown axons had reached the end of transected spinal cord.However, no regrown axons could be seen except scar formation in the control group.Conclusions: Cryopreserved OECs could integrated with the host and

  14. Fasciculation and guidance of spinal motor axons in the absence of FGFR2 signaling.

    Directory of Open Access Journals (Sweden)

    Rosa-Eva Huettl

    Full Text Available During development, fibroblast growth factors (FGF are essential for early patterning events along the anterior-posterior axis, conferring positional identity to spinal motor neurons by activation of different Hox codes. In the periphery, signaling through one of four fibroblast growth factor receptors supports the development of the skeleton, as well as induction and maintenance of extremities. In previous studies, FGF receptor 2 (FGFR2 was found to interact with axon bound molecules involved in axon fasciculation and extension, thus rendering this receptor an interesting candidate for the promotion of proper peripheral innervation. However, while the involvement of FGFR2 in limb bud induction has been extensively studied, its role during axon elongation and formation of distinct nervous projections has not been addressed so far. We show here that motor neurons in the spinal cord express FGFR2 and other family members during the establishment of motor connections to the forelimb and axial musculature. Employing a conditional genetic approach to selectively ablate FGFR2 from motor neurons we found that the patterning of motor columns and the expression patterns of other FGF receptors and Sema3A in the motor columns of mutant embryos are not altered. In the absence of FGFR2 signaling, pathfinding of motor axons is intact, and also fasciculation, distal advancement of motor nerves and gross morphology and positioning of axonal projections are not altered. Our findings therefore show that FGFR2 is not required cell-autonomously in motor neurons during the formation of initial motor projections towards limb and axial musculature.

  15. Resolving the biophysics of axon transmembrane polarization in a single closed-form description

    International Nuclear Information System (INIS)

    When a depolarizing event occurs across a cell membrane there is a remarkable change in its electrical properties. A complete depolarization event produces a considerably rapid increase in voltage that propagates longitudinally along the axon and is accompanied by changes in axial conductance. A dynamically changing magnetic field is associated with the passage of the action potential down the axon. Over 75 years of research has gone into the quantification of this phenomenon. To date, no unified model exist that resolves transmembrane polarization in a closed-form description. Here, a simple but formative description of propagated signaling phenomena in the membrane of an axon is presented in closed-form. The focus is on using both biophysics and mathematical methods for elucidating the fundamental mechanisms governing transmembrane polarization. The results presented demonstrate how to resolve electromagnetic and thermodynamic factors that govern transmembrane potential. Computational results are supported by well-established quantitative descriptions of propagated signaling phenomena in the membrane of an axon. The findings demonstrate how intracellular conductance, the thermodynamics of magnetization, and current modulation function together in generating an action potential in a unified closed-form description. The work presented in this paper provides compelling evidence that three basic factors contribute to the propagated signaling in the membrane of an axon. It is anticipated this work will compel those in biophysics, physical biology, and in the computational neurosciences to probe deeper into the classical and quantum features of membrane magnetization and signaling. It is hoped that subsequent investigations of this sort will be advanced by the computational features of this model without having to resort to numerical methods of analysis

  16. Resolving the biophysics of axon transmembrane polarization in a single closed-form description

    Energy Technology Data Exchange (ETDEWEB)

    Melendy, Robert F., E-mail: rfmelendy@liberty.edu [School of Engineering and Computational Sciences, Liberty University, Lynchburg, Virginia 24515 (United States)

    2015-12-28

    When a depolarizing event occurs across a cell membrane there is a remarkable change in its electrical properties. A complete depolarization event produces a considerably rapid increase in voltage that propagates longitudinally along the axon and is accompanied by changes in axial conductance. A dynamically changing magnetic field is associated with the passage of the action potential down the axon. Over 75 years of research has gone into the quantification of this phenomenon. To date, no unified model exist that resolves transmembrane polarization in a closed-form description. Here, a simple but formative description of propagated signaling phenomena in the membrane of an axon is presented in closed-form. The focus is on using both biophysics and mathematical methods for elucidating the fundamental mechanisms governing transmembrane polarization. The results presented demonstrate how to resolve electromagnetic and thermodynamic factors that govern transmembrane potential. Computational results are supported by well-established quantitative descriptions of propagated signaling phenomena in the membrane of an axon. The findings demonstrate how intracellular conductance, the thermodynamics of magnetization, and current modulation function together in generating an action potential in a unified closed-form description. The work presented in this paper provides compelling evidence that three basic factors contribute to the propagated signaling in the membrane of an axon. It is anticipated this work will compel those in biophysics, physical biology, and in the computational neurosciences to probe deeper into the classical and quantum features of membrane magnetization and signaling. It is hoped that subsequent investigations of this sort will be advanced by the computational features of this model without having to resort to numerical methods of analysis.

  17. Axonal diameter and density estimated with 7-Tesla hybrid diffusion imaging in transgenic Alzheimer rats

    Science.gov (United States)

    Daianu, Madelaine; Jacobs, Russell E.; Town, Terrence; Thompson, Paul M.

    2016-03-01

    Diffusion-weighted MR imaging (DWI) is a powerful tool to study brain tissue microstructure. DWI is sensitive to subtle changes in the white matter (WM), and can provide insight into abnormal brain changes in diseases such as Alzheimer's disease (AD). In this study, we used 7-Tesla hybrid diffusion imaging (HYDI) to scan 3 transgenic rats (line TgF344-AD; that model the full clinico-pathological spectrum of the human disease) ex vivo at 10, 15 and 24 months. We acquired 300 DWI volumes across 5 q-sampling shells (b=1000, 3000, 4000, 8000, 12000 s/mm2). From the top three b-value shells with highest signal-to-noise ratios, we reconstructed markers of WM disease, including indices of axon density and diameter in the corpus callosum (CC) - directly quantifying processes that occur in AD. As expected, apparent anisotropy progressively decreased with age; there were also decreases in the intra- and extra-axonal MR signal along axons. Axonal diameters were larger in segments of the CC (splenium and body, but not genu), possibly indicating neuritic dystrophy - characterized by enlarged axons and dendrites as previously observed at the ultrastructural level (see Cohen et al., J. Neurosci. 2013). This was further supported by increases in MR signals trapped in glial cells, CSF and possibly other small compartments in WM structures. Finally, tractography detected fewer fibers in the CC at 10 versus 24 months of age. These novel findings offer great potential to provide technical and scientific insight into the biology of brain disease.

  18. Resolving the biophysics of axon transmembrane polarization in a single closed-form description

    Science.gov (United States)

    Melendy, Robert F.

    2015-12-01

    When a depolarizing event occurs across a cell membrane there is a remarkable change in its electrical properties. A complete depolarization event produces a considerably rapid increase in voltage that propagates longitudinally along the axon and is accompanied by changes in axial conductance. A dynamically changing magnetic field is associated with the passage of the action potential down the axon. Over 75 years of research has gone into the quantification of this phenomenon. To date, no unified model exist that resolves transmembrane polarization in a closed-form description. Here, a simple but formative description of propagated signaling phenomena in the membrane of an axon is presented in closed-form. The focus is on using both biophysics and mathematical methods for elucidating the fundamental mechanisms governing transmembrane polarization. The results presented demonstrate how to resolve electromagnetic and thermodynamic factors that govern transmembrane potential. Computational results are supported by well-established quantitative descriptions of propagated signaling phenomena in the membrane of an axon. The findings demonstrate how intracellular conductance, the thermodynamics of magnetization, and current modulation function together in generating an action potential in a unified closed-form description. The work presented in this paper provides compelling evidence that three basic factors contribute to the propagated signaling in the membrane of an axon. It is anticipated this work will compel those in biophysics, physical biology, and in the computational neurosciences to probe deeper into the classical and quantum features of membrane magnetization and signaling. It is hoped that subsequent investigations of this sort will be advanced by the computational features of this model without having to resort to numerical methods of analysis.

  19. Organophosphates induce distal axonal damage, but not brain oedema, by inactivating neuropathy target esterase

    International Nuclear Information System (INIS)

    Single doses of organophosphorus compounds (OP) which covalently inhibit neuropathy target esterase (NTE) can induce lower-limb paralysis and distal damage in long nerve axons. Clinical signs of neuropathy are evident 3 weeks post-OP dose in humans, cats and chickens. By contrast, clinical neuropathy in mice following acute dosing with OPs or any other toxic compound has never been reported. Moreover, dosing mice with ethyloctylphosphonofluoridate (EOPF) - an extremely potent NTE inhibitor - causes a different (subacute) neurotoxicity with brain oedema. These observations have raised the possibility that mice are intrinsically resistant to neuropathies induced by acute toxic insult, but may incur brain oedema, rather than distal axonal damage, when NTE is inactivated. Here we provide the first report that hind-limb dysfunction and extensive axonal damage can occur in mice 3 weeks after acute dosing with a toxic compound, bromophenylacetylurea. Three weeks after acutely dosing mice with neuropathic OPs no clinical signs were observed, but distal lesions were present in the longest spinal sensory axons. Similar lesions were evident in undosed nestin-cre:NTEfl/fl mice in which NTE had been genetically-deleted from neural tissue. The extent of OP-induced axonal damage in mice was related to the duration of NTE inactivation and, as reported in chickens, was promoted by post-dosing with phenylmethanesulfonylfluoride. However, phenyldipentylphosphinate, another promoting compound in chickens, itself induced in mice lesions different from the neuropathic OP type. Finally, EOPF induced subacute neurotoxicity with brain oedema in both wild-type and nestin-cre:NTEfl/fl mice indicating that the molecular target for this effect is not neural NTE.

  20. Impaired Axonal Na(+) Current by Hindlimb Unloading: Implication for Disuse Neuromuscular Atrophy.

    Science.gov (United States)

    Banzrai, Chimeglkham; Nodera, Hiroyuki; Kawarai, Toshitaka; Higashi, Saki; Okada, Ryo; Mori, Atsuko; Shimatani, Yoshimitsu; Osaki, Yusuke; Kaji, Ryuji

    2016-01-01

    This study aimed to characterize the excitability changes in peripheral motor axons caused by hindlimb unloading (HLU), which is a model of disuse neuromuscular atrophy. HLU was performed in normal 8-week-old male mice by fixing the proximal tail by a clip connected to the top of the animal's cage for 3 weeks. Axonal excitability studies were performed by stimulating the sciatic nerve at the ankle and recording the compound muscle action potential (CMAP) from the foot. The amplitudes of the motor responses of the unloading group were 51% of the control amplitudes [2.2 ± 1.3 mV (HLU) vs. 4.3 ± 1.2 mV (Control), P = 0.03]. Multiple axonal excitability analysis showed that the unloading group had a smaller strength-duration time constant (SDTC) and late subexcitability (recovery cycle) than the controls [0.075 ± 0.01 (HLU) vs. 0.12 ± 0.01 (Control), P < 0.01; 5.4 ± 1.0 (HLU) vs. 10.0 ± 1.3 % (Control), P = 0.01, respectively]. Three weeks after releasing from HLU, the SDTC became comparable to the control range. Using a modeling study, the observed differences in the waveforms could be explained by reduced persistent Na(+) currents along with parameters related to current leakage. Quantification of RNA of a SCA1A gene coding a voltage-gated Na(+) channel tended to be decreased in the sciatic nerve in HLU. The present study suggested that axonal ion currents are altered in vivo by HLU. It is still undetermined whether the dysfunctional axonal ion currents have any pathogenicity on neuromuscular atrophy or are the results of neural plasticity by atrophy. PMID:26909041