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Christensen PC, Welch NC, Brideau C, Stys PK. Functional ionotropic glutamate receptors on peripheral axons and myelin. Muscle Nerve 2016; 54:451-9. [DOI: 10.1002/mus.25078] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 01/26/2016] [Accepted: 02/10/2016] [Indexed: 01/22/2023]
Affiliation(s)
- Pia Crone Christensen
- Hotchkiss Brain Institute, Department of Clinical Neurosciences, 3330 Hospital Drive NW, University of Calgary; Calgary Alberta Canada T2N 4N1
| | - Nicole Cheryl Welch
- Hotchkiss Brain Institute, Department of Clinical Neurosciences, 3330 Hospital Drive NW, University of Calgary; Calgary Alberta Canada T2N 4N1
| | - Craig Brideau
- Hotchkiss Brain Institute, Department of Clinical Neurosciences, 3330 Hospital Drive NW, University of Calgary; Calgary Alberta Canada T2N 4N1
| | - Peter K. Stys
- Hotchkiss Brain Institute, Department of Clinical Neurosciences, 3330 Hospital Drive NW, University of Calgary; Calgary Alberta Canada T2N 4N1
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52
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Schießl IM, Castrop H. Deep insights: intravital imaging with two-photon microscopy. Pflugers Arch 2016; 468:1505-16. [PMID: 27352273 DOI: 10.1007/s00424-016-1832-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 04/26/2016] [Indexed: 01/03/2023]
Abstract
Intravital multiphoton microscopy is widely used to assess the structure and function of organs in live animals. Although different tissues vary in their accessibility for intravital multiphoton imaging, considerable progress has been made in the imaging quality of all tissues due to substantial technical improvements in the relevant imaging components, such as optics, excitation laser, detectors, and signal analysis software. In this review, we provide an overview of the technical background of intravital multiphoton microscopy. Then, we note a few seminal findings that were made through the use of multiphoton microscopy. Finally, we address the technical limitations of the method and provide an outlook for how these limitations may be overcome through future technical developments.
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Affiliation(s)
- Ina Maria Schießl
- Institute of Physiology, University of Regensburg, Universitätsstr. 31, 93040, Regensburg, Germany.
| | - Hayo Castrop
- Institute of Physiology, University of Regensburg, Universitätsstr. 31, 93040, Regensburg, Germany
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53
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Saab AS, Tzvetavona ID, Trevisiol A, Baltan S, Dibaj P, Kusch K, Möbius W, Goetze B, Jahn HM, Huang W, Steffens H, Schomburg ED, Pérez-Samartín A, Pérez-Cerdá F, Bakhtiari D, Matute C, Löwel S, Griesinger C, Hirrlinger J, Kirchhoff F, Nave KA. Oligodendroglial NMDA Receptors Regulate Glucose Import and Axonal Energy Metabolism. Neuron 2016; 91:119-32. [PMID: 27292539 DOI: 10.1016/j.neuron.2016.05.016] [Citation(s) in RCA: 324] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 03/11/2016] [Accepted: 05/05/2016] [Indexed: 11/17/2022]
Abstract
Oligodendrocytes make myelin and support axons metabolically with lactate. However, it is unknown how glucose utilization and glycolysis are adapted to the different axonal energy demands. Spiking axons release glutamate and oligodendrocytes express NMDA receptors of unknown function. Here we show that the stimulation of oligodendroglial NMDA receptors mobilizes glucose transporter GLUT1, leading to its incorporation into the myelin compartment in vivo. When myelinated optic nerves from conditional NMDA receptor mutants are challenged with transient oxygen-glucose deprivation, they show a reduced functional recovery when returned to oxygen-glucose but are indistinguishable from wild-type when provided with oxygen-lactate. Moreover, the functional integrity of isolated optic nerves, which are electrically silent, is extended by preincubation with NMDA, mimicking axonal activity, and shortened by NMDA receptor blockers. This reveals a novel aspect of neuronal energy metabolism in which activity-dependent glutamate release enhances oligodendroglial glucose uptake and glycolytic support of fast spiking axons.
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Affiliation(s)
- Aiman S Saab
- Max Planck Institute of Experimental Medicine, Department of Neurogenetics, Göttingen 37075, Germany; Center for Integrative Physiology and Molecular Medicine, Molecular Physiology, University of Saarland, Homburg 66421, Germany; University of Zurich, Institute of Pharmacology and Toxicology, 8057 Zurich, Switzerland
| | - Iva D Tzvetavona
- Max Planck Institute of Experimental Medicine, Department of Neurogenetics, Göttingen 37075, Germany
| | - Andrea Trevisiol
- Max Planck Institute of Experimental Medicine, Department of Neurogenetics, Göttingen 37075, Germany
| | - Selva Baltan
- Lerner Research Institute, Cleveland Clinic, Department of Neurosciences, Cleveland, OH 44195, USA
| | - Payam Dibaj
- Max Planck Institute of Experimental Medicine, Department of Neurogenetics, Göttingen 37075, Germany
| | - Kathrin Kusch
- Max Planck Institute of Experimental Medicine, Department of Neurogenetics, Göttingen 37075, Germany
| | - Wiebke Möbius
- Max Planck Institute of Experimental Medicine, Department of Neurogenetics, Göttingen 37075, Germany; Center Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), 37073 Göttingen, Germany
| | - Bianka Goetze
- Bernstein Focus for Neurotechnology (BFNT) and School of Biology, Department of Systems Neuroscience, University of Göttingen, 37075 Göttingen, Germany
| | - Hannah M Jahn
- Max Planck Institute of Experimental Medicine, Department of Neurogenetics, Göttingen 37075, Germany; Center for Integrative Physiology and Molecular Medicine, Molecular Physiology, University of Saarland, Homburg 66421, Germany
| | - Wenhui Huang
- Max Planck Institute of Experimental Medicine, Department of Neurogenetics, Göttingen 37075, Germany; Center for Integrative Physiology and Molecular Medicine, Molecular Physiology, University of Saarland, Homburg 66421, Germany
| | - Heinz Steffens
- Institute of Physiology, University of Göttingen, 37073 Göttingen, Germany; Max Planck Institute for Biophysical Chemistry, Department of NanoBiophotonics, 37077 Göttingen, Germany
| | - Eike D Schomburg
- Institute of Physiology, University of Göttingen, 37073 Göttingen, Germany
| | - Alberto Pérez-Samartín
- Universidad del País Vasco, CIBERNED and Departamento de Neurociencias and Achucarro Basque Center for Neuroscience, Leioa 48940, Spain
| | - Fernando Pérez-Cerdá
- Universidad del País Vasco, CIBERNED and Departamento de Neurociencias and Achucarro Basque Center for Neuroscience, Leioa 48940, Spain
| | - Davood Bakhtiari
- Center Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), 37073 Göttingen, Germany; Department of NMR Based Structural Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Carlos Matute
- Universidad del País Vasco, CIBERNED and Departamento de Neurociencias and Achucarro Basque Center for Neuroscience, Leioa 48940, Spain
| | - Siegrid Löwel
- Bernstein Focus for Neurotechnology (BFNT) and School of Biology, Department of Systems Neuroscience, University of Göttingen, 37075 Göttingen, Germany
| | - Christian Griesinger
- Center Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), 37073 Göttingen, Germany; Department of NMR Based Structural Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Johannes Hirrlinger
- Max Planck Institute of Experimental Medicine, Department of Neurogenetics, Göttingen 37075, Germany; Carl-Ludwig-Institute for Physiology, Faculty of Medicine, University of Leipzig, 04103 Leipzig, Germany
| | - Frank Kirchhoff
- Max Planck Institute of Experimental Medicine, Department of Neurogenetics, Göttingen 37075, Germany; Center for Integrative Physiology and Molecular Medicine, Molecular Physiology, University of Saarland, Homburg 66421, Germany; Center Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), 37073 Göttingen, Germany.
| | - Klaus-Armin Nave
- Max Planck Institute of Experimental Medicine, Department of Neurogenetics, Göttingen 37075, Germany; Center Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), 37073 Göttingen, Germany.
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54
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Bao FX, Shi HY, Long Q, Yang L, Wu Y, Ying ZF, Qin DJ, Zhang J, Guo YP, Li HM, Liu XG. Mitochondrial Membrane Potential-dependent Endoplasmic Reticulum Fragmentation is an Important Step in Neuritic Degeneration. CNS Neurosci Ther 2016; 22:648-60. [PMID: 27080255 DOI: 10.1111/cns.12547] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 03/17/2016] [Accepted: 03/20/2016] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Neuritic degeneration is an important early pathological step in neurodegeneration. AIM The purpose of this study was to explore the mechanisms connecting neuritic degeneration to the functional and morphological remodeling of endoplasmic reticulum (ER) and mitochondria. METHODS Here, we set up neuritic degeneration models by neurite cutting-induced neural degeneration in human-induced pluripotent stem cell-derived neurons. RESULTS We found that neuritic ER becomes fragmented and forms complexes with mitochondria, which induces IP3R-dependent mitochondrial Ca(2+) elevation and dysfunction during neuritic degeneration. Furthermore, mitochondrial membrane potential is required for ER fragmentation and mitochondrial Ca(2+) elevation during neuritic degeneration. Mechanically, tightening of the ER-mitochondria associations by expression of a short "synthetic linker" and ER Ca(2+) releasing together could promote mitochondrial Ca(2+) elevation, dysfunction, and reactive oxygen species generation. CONCLUSION Our study reveals a dynamic remodeling of the ER-mitochondria interface underlying neuritic degeneration.
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Affiliation(s)
- Fei-Xiang Bao
- University of Science and Technology of China, Hefei, Anhui, China.,Key Laboratory of Regenerative Biology, Guangdong provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
| | - Hong-Yan Shi
- University of Science and Technology of China, Hefei, Anhui, China.,Key Laboratory of Regenerative Biology, Guangdong provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China.,Institute of Health Sciences, Anhui University, Hefei, China
| | - Qi Long
- University of Science and Technology of China, Hefei, Anhui, China.,Key Laboratory of Regenerative Biology, Guangdong provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
| | - Liang Yang
- University of Science and Technology of China, Hefei, Anhui, China.,Key Laboratory of Regenerative Biology, Guangdong provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
| | - Yi Wu
- University of Science and Technology of China, Hefei, Anhui, China.,Key Laboratory of Regenerative Biology, Guangdong provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
| | - Zhong-Fu Ying
- University of Science and Technology of China, Hefei, Anhui, China.,Key Laboratory of Regenerative Biology, Guangdong provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
| | - Da-Jiang Qin
- University of Science and Technology of China, Hefei, Anhui, China.,Key Laboratory of Regenerative Biology, Guangdong provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
| | - Jian Zhang
- University of Science and Technology of China, Hefei, Anhui, China.,Key Laboratory of Regenerative Biology, Guangdong provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
| | - Yi-Ping Guo
- University of Science and Technology of China, Hefei, Anhui, China.,Key Laboratory of Regenerative Biology, Guangdong provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
| | - Hong-Mei Li
- University of Science and Technology of China, Hefei, Anhui, China.,Key Laboratory of Regenerative Biology, Guangdong provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
| | - Xing-Guo Liu
- University of Science and Technology of China, Hefei, Anhui, China.,Key Laboratory of Regenerative Biology, Guangdong provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
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55
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Ke T, Li R, Chen W. Inhibition of the NMDA receptor protects the rat sciatic nerve against ischemia/reperfusion injury. Exp Ther Med 2016; 11:1563-1572. [PMID: 27168774 PMCID: PMC4840580 DOI: 10.3892/etm.2016.3148] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 11/25/2015] [Indexed: 12/23/2022] Open
Abstract
Inhibition of the N-methyl-D-aspartate (NMDA) receptor by MK-801 reduces ischemia/reperfusion (I/R) injury in the central nervous system. However, few previous studies have evaluated the neuroprotective effects of MK-801 against peripheral I/R injury. The present study aimed to investigate the protective effects of MK-801 pretreatment against I/R injury in the rat sciatic nerve (SN). Sprague-Dawley rats were subjected to a sham surgery (n=8) or to a 5-h ischemic insult by femoral artery clamping (I/R and I/R+MK-801 groups; n=48 per group). I/R+MK-801 rats were intraperitoneally injected with MK-801 (0.5 ml or 1 mg/kg) at 15 min prior to reperfusion. The rats were sacrificed at 0, 6, 12, 24, 72 h, or 7 days following reperfusion. Plasma malondialdehyde (MDA) and nitric oxide (NO) concentrations, and SN inducible NO synthase (iNOS) protein expression levels, were measured using colorimetry. In addition, the protein expression levels of tumor necrosis factor-α (TNF-α) were measured using immunohistochemistry, and histological analyses of the rat SN were conducted using light and electron microscopy. Alterations in the mRNA expression levels of TNF-α and TNF-α converting enzyme (TACE) in the rat SN were detected using reverse transcription-quantitative polymerase chain reaction. In the I/R group, plasma concentrations of NO (175.3±4.2 µmol/l) and MDA (16.2±1.9 mmol/l), and the levels of iNOS (2.5±0.3) in the SN, peaked at 24 h post-reperfusion. At 24 h, pretreatment with MK-801 significantly reduced plasma NO (107.3±3.6 µmol/l) and MDA (11.8±1.6 mmol/l), and SN iNOS (1.65±0.2) levels (all P<0.01). The mRNA expression levels of TNF-α and TACE in the SN were significantly reduced in the I/R+MK-801 group, as compared with the I/R group (P<0.05). Furthermore, MK-801 pretreatment was shown to have alleviated histological signs of I/R injury, including immune cell infiltration and axon demyelination. The results of the present study suggested that pretreatment with MK-801 may alleviate I/R injury of the SN by inhibiting the activation of TNF-α and reducing the levels of iNOS in the SN.
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Affiliation(s)
- Tie Ke
- Department of Emergency Surgery, Fujian Provincial Hospital, Fujian Medical University, Fuzhou, Fujian 350001, P.R. China; Emergency Center of Fujian Province, Fujian Medical University, Fuzhou, Fujian 350001, P.R. China; Provincial Clinical Medical College, Fujian Medical University, Fuzhou, Fujian 350001, P.R. China
| | - Renbin Li
- Department of Orthopedics, The Affiliated Fuzhou Second Hospital, Xiamen University, Fuzhou, Fujian 350007, P.R. China
| | - Wenchang Chen
- Department of Emergency Surgery, Fujian Provincial Hospital, Fujian Medical University, Fuzhou, Fujian 350001, P.R. China
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56
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Kızılay Z, Erken HA, Çetin NK, Aktaş S, Abas Bİ, Yılmaz A. Boric acid reduces axonal and myelin damage in experimental sciatic nerve injury. Neural Regen Res 2016; 11:1660-1665. [PMID: 27904499 PMCID: PMC5116847 DOI: 10.4103/1673-5374.193247] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The aim of this study was to investigate the effects of boric acid in experimental acute sciatic nerve injury. Twenty-eight adult male rats were randomly divided into four equal groups (n = 7): control (C), boric acid (BA), sciatic nerve injury (I), and sciatic nerve injury + boric acid treatment (BAI). Sciatic nerve injury was generated using a Yasargil aneurysm clip in the groups I and BAI. Boric acid was given four times at 100 mg/kg to rats in the groups BA and BAI after injury (by gavage at 0, 24, 48 and 72 hours) but no injury was made in the group BA. In vivo electrophysiological tests were performed at the end of the day 4 and sciatic nerve tissue samples were taken for histopathological examination. The amplitude of compound action potential, the nerve conduction velocity and the number of axons were significantly lower and the myelin structure was found to be broken in group I compared with those in groups C and BA. However, the amplitude of the compound action potential, the nerve conduction velocity and the number of axons were significantly greater in group BAI than in group I. Moreover, myelin injury was significantly milder and the intensity of nuclear factor kappa B immunostaining was significantly weaker in group BAI than in group I. The results of this study show that administration of boric acid at 100 mg/kg after sciatic nerve injury in rats markedly reduces myelin and axonal injury and improves the electrophysiological function of injured sciatic nerve possibly through alleviating oxidative stress reactions.
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Affiliation(s)
- Zahir Kızılay
- Department of Neurosurgery, Faculty of Medicine, Adnan Menderes University, Aydin, Turkey
| | - Haydar Ali Erken
- Department of Physiology, Faculty of Medicine, Balikesir University, Balikesir, Turkey
| | - Nesibe Kahraman Çetin
- Department of Pathology, Faculty of Medicine, Adnan Menderes University, Aydin, Turkey
| | - Serdar Aktaş
- Department of Pharmacology and Toxicology, Faculty of Medicine, Adnan Menderes University, Aydin, Turkey
| | - Burçin İrem Abas
- Department of Clinical Biochemistry, Faculty of Medicine, Adnan Menderes University, Aydin, Turkey
| | - Ali Yılmaz
- Department of Neurosurgery, Faculty of Medicine, Adnan Menderes University, Aydin, Turkey
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57
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Abstract
Injury to central nervous system axons is a common early characteristic of neurodegenerative diseases. Depending on its location and the type of neuron, axon injury often leads to axon degeneration, retrograde neuronal cell death and progressive permanent loss of vital neuronal functions. Although these sequential events are clearly connected, ample evidence indicates that neuronal soma and axon degenerations are active autonomous processes with distinct molecular mechanisms. By exploiting the anatomical and technical advantages of the retinal ganglion cell (RGC)/optic nerve (ON) system, we demonstrated that inhibition of the PERK-eIF2α-CHOP pathway and activation of the X-box binding protein 1 pathway synergistically protect RGC soma and axon, and preserve visual function, in both acute ON traumatic injury and chronic glaucomatous neuropathy. The autonomous endoplasmic reticulum (ER) stress pathway in neurons has been implicated in several other neurodegenerative diseases. In addition to the emerging role of ER morphology in axon maintenance, we propose that ER stress is a common upstream signal for disturbances in axon integrity, and that it leads to a retrograde signal that can subsequently induce neuronal soma death. Therefore manipulation of the ER stress pathway may be a key step toward developing the effective neuroprotectants that are greatly needed in the clinic.
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Affiliation(s)
- Yang Hu
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Temple University School of Medicine, Philadelphia, PA, USA
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58
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Volman V, Ng LJ. Perinodal glial swelling mitigates axonal degradation in a model of axonal injury. J Neurophysiol 2015; 115:1003-17. [PMID: 26683073 DOI: 10.1152/jn.00912.2015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 12/13/2015] [Indexed: 12/15/2022] Open
Abstract
Mild traumatic brain injury (mTBI) has been associated with the damage to myelinated axons in white matter tracts. Animal models and in vitro studies suggest that axonal degradation develops during a latent period following a traumatic event. This delay has been attributed to slowly developing axonal membrane depolarization that is initiated by injury-induced ionic imbalance and in turn, leads to the activation of Ca(2+) proteases via pathological accumulation of Ca(2+). However, the mechanisms mitigating the transition to axonal degradation after injury remain elusive. We addressed this question in a detailed biophysical model of axonal injury that incorporated ion exchange and glial swelling mechanisms. We show that glial swelling, which often co-occurs with mTBI, promotes axonal survival by regulating extracellular K(+) dynamics, extending the range of injury parameters in which axons exhibit stable membrane potential postinjury. In addition, glial swelling was instrumental in reducing axonal sensitivity to repetitive stretch injury that occurred several minutes following the first one. Results of this study suggest that acute post-traumatic swelling of perinodal astrocytes helps prevent or postpone axonal degradation by maintaining physiologically relevant levels of extracellular K(+).
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Affiliation(s)
- Vladislav Volman
- Simulation, Engineering, and Testing, L-3 Applied Technologies Incorporated, San Diego, California
| | - Laurel J Ng
- Simulation, Engineering, and Testing, L-3 Applied Technologies Incorporated, San Diego, California
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59
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Conte A, Li Voti P, Pontecorvo S, Quartuccio ME, Baione V, Rocchi L, Cortese A, Bologna M, Francia A, Berardelli A. Attention-related changes in short-term cortical plasticity help to explain fatigue in multiple sclerosis. Mult Scler 2015; 22:1359-66. [PMID: 26672995 DOI: 10.1177/1352458515619780] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 10/26/2015] [Indexed: 12/25/2022]
Abstract
BACKGROUND In multiple sclerosis (MS), pathophysiology of fatigue is only partially known. OBJECTIVE The aim of this study was to investigate whether the attention-induced modulation on short- and long-term cortical plasticity mechanisms in primary motor area (M1) is abnormal in patients with MS-related fatigue. METHODS All participants underwent 5-Hz repetitive transcranial magnetic stimulation (rTMS), reflecting short-term plasticity, and paired associative stimulation (PAS), reflecting long-term plasticity, and were asked to focus their attention on the hand contralateral to the M1 stimulated. A group of age-matched healthy subjects acted as control. RESULTS In patients with MS, 5-Hz rTMS and PAS failed to induce the normal increase in motor-evoked potential (MEP). During the attention-demanding condition, 5-Hz rTMS- and PAS-induced responses differed in patients with MS with and without fatigue. Whereas in patients with fatigue neither technique induced the attention-induced MEP increase, in patients without fatigue they both increased the MEP response, although they did so less efficiently than in healthy subjects. Attention-induced changes in short-term cortical plasticity inversely correlated with fatigue severity. CONCLUSION Short-term and long-term plasticity mechanisms are abnormal in MS possibly owing to widespread changes in ion-channel expression. Fatigue in MS reflects disrupted cortical attentional networks related to movement control.
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Affiliation(s)
- Antonella Conte
- IRCCS Neuromed Institute, Pozzilli, ItalyDepartment of Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy
| | | | | | | | - Viola Baione
- Department of Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy
| | - Lorenzo Rocchi
- Department of Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy
| | - Antonio Cortese
- Department of Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy
| | | | - Ada Francia
- Department of Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy
| | - Alfredo Berardelli
- IRCCS Neuromed Institute, Pozzilli, ItalyDepartment of Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy
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60
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Ewan EE, Hagg T. Intrathecal Acetyl-L-Carnitine Protects Tissue and Improves Function after a Mild Contusive Spinal Cord Injury in Rats. J Neurotrauma 2015; 33:269-77. [PMID: 26415041 DOI: 10.1089/neu.2015.4030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Primary and secondary ischemia after spinal cord injury (SCI) contributes to tissue and axon degeneration, which may result from decreased energy substrate availability for cellular and axonal mitochondrial adenosine triphosphate (ATP) production. Therefore, providing spinal tissue with an alternative energy substrate during ischemia may be neuroprotective after SCI. To assess this, rats received a mild contusive SCI (120 kdyn, Infinite Horizons impactor) at thoracic level 9 (T9), which causes loss of ∼ 80% of the ascending sensory dorsal column axonal projections to the gracile nucleus. Immediately afterwards, the energy substrate acetyl-L-carnitine (ALC; 1 mg/day) or phosphate-buffered saline (PBS) was infused intrathecally (sub-arachnoid) for 6 days via an L5/6 catheter attached to a subcutaneous Alzet pump. ALC treatment improved overground locomotor function (Basso-Beattie-Breshnahan [BBB] score 18 vs. 13) at 6 days, total spared epicenter (71% vs. 57%) and penumbra white matter (90% vs. 85%), ventral penumbra microvessels (108% vs. 79%), and penumbra motor neurons (42% vs. 15%) at 15 days post-SCI, compared with PBS treatment. However, the ascending sensory projections (anterogradely traced with cholera toxin B from the sciatic nerves) and dorsal column white matter and perfused blood vessels were not protected. Furthermore, grid walking, a task we have shown to be dependent on dorsal column function, was not improved. Thus, mitochondrial substrate replacement may only be efficacious in areas of lesser or temporary ischemia, such as the ventral spinal cord and injury penumbra in this study. The current data also support our previous evidence that microvessel loss is central to secondary tissue degeneration.
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Affiliation(s)
- Eric E Ewan
- Kentucky Spinal Cord Injury Research Center and Department of Neurological Surgery, University of Louisville , Louisville, Kentucky
| | - Theo Hagg
- Kentucky Spinal Cord Injury Research Center and Department of Neurological Surgery, University of Louisville , Louisville, Kentucky
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61
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Lee JY, Biemond M, Petratos S. Axonal degeneration in multiple sclerosis: defining therapeutic targets by identifying the causes of pathology. Neurodegener Dis Manag 2015; 5:527-48. [DOI: 10.2217/nmt.15.50] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
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.
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Affiliation(s)
- Jae Young Lee
- Department of Medicine, Central Clinical School, Monash University, Prahran VIC 3004, Australia
| | - Melissa Biemond
- Department of Medicine, Central Clinical School, Monash University, Prahran VIC 3004, Australia
| | - Steven Petratos
- Department of Medicine, Central Clinical School, Monash University, Prahran VIC 3004, Australia
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62
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Zhang Z, David G. Stimulation-induced Ca(2+) influx at nodes of Ranvier in mouse peripheral motor axons. J Physiol 2015; 594:39-57. [PMID: 26365250 DOI: 10.1113/jp271207] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 09/03/2015] [Indexed: 01/26/2023] Open
Abstract
KEY POINTS In peripheral myelinated axons of mammalian spinal motor neurons, Ca(2+) influx was thought to occur only in pathological conditions such as ischaemia. Using Ca(2+) imaging in mouse large motor axons, we find that physiological stimulation with trains of action potentials transiently elevates axoplasmic [C(2+)] around nodes of Ranvier. These stimulation-induced [Ca(2+)] elevations require Ca(2+) influx, and are partially reduced by blocking T-type Ca(2+) channels (e.g. mibefradil) and by blocking the Na(+)/Ca(2+) exchanger (NCX), suggesting an important contribution of Ca(2+) influx via reverse-mode NCX activity. Acute disruption of paranodal myelin dramatically increases stimulation-induced [Ca(2+)] elevations around nodes by allowing activation of sub-myelin L-type (nimodipine-sensitive) Ca(2+) channels. The Ca(2+) that enters myelinated motor axons during normal activity is likely to contribute to several signalling pathways; the larger Ca(2+) influx that occurs following demyelination may contribute to the axonal degeneration that occurs in peripheral demyelinating diseases. Activity-dependent Ca(2+) signalling is well established for somata and terminals of mammalian spinal motor neurons, but not for their axons. Imaging of an intra-axonally injected fluorescent [Ca(2+)] indicator revealed that during repetitive action potential stimulation, [Ca(2+)] elevations localized to nodal regions occurred in mouse motor axons from ventral roots, phrenic nerve and intramuscular branches. These [Ca(2+)] elevations (∼ 0.1 μm with stimulation at 50 Hz, 10 s) were blocked by removal of Ca(2+) from the extracellular solution. Effects of pharmacological blockers indicated contributions from both T-type Ca(2+) channels and reverse mode Na(+)/Ca(2+) exchange (NCX). Acute disruption of paranodal myelin (by stretch or lysophosphatidylcholine) increased the stimulation-induced [Ca(2+)] elevations, which now included a prominent contribution from L-type Ca(2+) channels. These results suggest that the peri-nodal axolemma of motor axons includes multiple pathways for stimulation-induced Ca(2+) influx, some active in normally-myelinated axons (T-type channels, NCX), others active only when exposed by myelin disruption (L-type channels). The modest axoplasmic peri-nodal [Ca(2+)] elevations measured in intact motor axons might mediate local responses to axonal activation. The larger [Ca(2+) ] elevations measured after myelin disruption might, over time, contribute to the axonal degeneration observed in peripheral demyelinating neuropathies.
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Affiliation(s)
- Zhongsheng Zhang
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, 1600 NW 10th Ave., Miami, FL, 33136, USA
| | - Gavriel David
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, 1600 NW 10th Ave., Miami, FL, 33136, USA.,Neuroscience Program, University of Miami Miller School of Medicine, PO Box 011351, Miami, FL, 33101, USA
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Rosenzweig S, Carmichael ST. The axon-glia unit in white matter stroke: mechanisms of damage and recovery. Brain Res 2015; 1623:123-34. [PMID: 25704204 PMCID: PMC4545468 DOI: 10.1016/j.brainres.2015.02.019] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2015] [Accepted: 02/10/2015] [Indexed: 01/07/2023]
Abstract
Approximately one quarter of all strokes in humans occur in white matter, and the progressive nature of white matter lesions often results in severe physical and mental disability. Unlike cortical grey matter stroke, the pathology of white matter stroke revolves around disrupted connectivity and injured axons and glial cells, rather than neuronal cell bodies. Consequently, the mechanisms behind ischemic damage to white matter elements, the regenerative responses of glial cells and their signaling pathways, all differ significantly from those in grey matter. Development of effective therapies for white matter stroke would require an enhanced understanding of the complex cellular and molecular interactions within the white matter, leading to the identification of new therapeutic targets. This review will address the unique properties of the axon-glia unit during white matter stroke, describe the challenging process of promoting effective white matter repair, and discuss recently-identified signaling pathways which may hold potential targets for repair in this disease. This article is part of a Special Issue entitled SI: Cell Interactions In Stroke.
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Affiliation(s)
- Shira Rosenzweig
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
| | - S Thomas Carmichael
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
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64
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Sato T, Ishikawa M, Yoshihara T, Nakazato R, Higashida H, Asano M, Yoshioka K. Critical role of JSAP1 and JLP in axonal transport in the cerebellar Purkinje cells of mice. FEBS Lett 2015; 589:2805-11. [PMID: 26320416 DOI: 10.1016/j.febslet.2015.08.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 08/01/2015] [Accepted: 08/13/2015] [Indexed: 11/15/2022]
Abstract
JNK/stress-activated protein kinase-associated protein 1 (JSAP1) and JNK-associated leucine zipper protein (JLP) are structurally related scaffolding proteins that are highly expressed in the brain. Here, we found that JSAP1 and JLP play functionally redundant and essential roles in mouse cerebellar Purkinje cell (PC) survival. Mice containing PCs with deletions in both JSAP1 and JLP exhibited PC axonal dystrophy, followed by gradual, progressive neuronal loss. Kinesin-1 cargoes accumulated selectively in the swollen axons of Jsap1/Jlp-deficient PCs. In addition, autophagy inactivation in these mice markedly accelerated PC degeneration. These findings suggest that JSAP1 and JLP play critical roles in kinesin-1-dependent axonal transport, which prevents brain neuronal degeneration.
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Affiliation(s)
- Tokiharu Sato
- Division of Molecular Cell Signaling, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Momoe Ishikawa
- Division of Molecular Cell Signaling, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Toru Yoshihara
- Division of Transgenic Animal Science, Advanced Science Research Center, Kanazawa University, Kanazawa 920-8640, Japan
| | - Ryota Nakazato
- Division of Molecular Cell Signaling, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Haruhiro Higashida
- Research Center for Child Mental Development, Kanazawa University, Kanazawa 920-8640, Japan
| | - Masahide Asano
- Division of Transgenic Animal Science, Advanced Science Research Center, Kanazawa University, Kanazawa 920-8640, Japan
| | - Katsuji Yoshioka
- Division of Molecular Cell Signaling, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
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Mu J, Song Y, Zhang J, Lin W, Dong H. Calcium signaling is implicated in the diffuse axonal injury of brain stem. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2015; 8:4388-4397. [PMID: 26191130 PMCID: PMC4503002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 02/21/2015] [Accepted: 04/13/2015] [Indexed: 06/04/2023]
Abstract
Evaluating diffuse axonal injury (DAI) remains challenging in clinical sciences since the physiopathologic mechanism of DAI is still unclear. The calcium overload in the axoplasm is considered to be crucial for secondary axonal injury. The present study use calcium channel blocker, nimodipine, to explore the influence of Ca2+ in the pathogenesis of rat DAI. In the DAI group, the expressions of β-APP and NF-L in axons were increased from 12 to 72 h. The ultrastructural observation indicated the axon and vessel injury appeared at 12 h post-injury and severely aggravated from 24 to 72 h. The expression of vWF and brain water content was increased at 12 h after injury and further increased at 24 h. Nimodipine decreased the expression of β-APP, NF-L and vWF, and also attenuated the ultrastructural damage of vascular wall and axons. Furthermore, Ca-dependent enzyme, the calcineurin activity were increased in DAI and nimodipine suppressed the activity of calcineurins (CaN). However, the amount of CaN expression was not changed. Our results showed that disturbances of axonal calcium homeostasis play an important role in the secondary damage of the axon, neuron and capillary vessel which may be related with activating CaN during the acute phase of DAI. Nimodipine can alleviate the secondary damage by suppressing the calcineurin activity.
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Affiliation(s)
- Jiao Mu
- Department of Forensic Medicine, Huazhong University of Science and Technology, Tongji Medical CollegeNo. 13 Hangkong Lu, Hankou, Wuhan 430030, Hubei, PR China
- Department of Pathology, Hebei North UniversityNo. 11 Zuanshinan Lu, Zhangjiakou 075000, Hebei, PR China
| | - Yucheng Song
- Criminal Investigation Brigade of TaicangNo. 128 Loujiangbei Lu, Taicang, Suzhou 215400, Jiangsu, PR China
| | - Ji Zhang
- Department of Forensic Medicine, Huazhong University of Science and Technology, Tongji Medical CollegeNo. 13 Hangkong Lu, Hankou, Wuhan 430030, Hubei, PR China
| | - Wei Lin
- Department of Forensic Medicine, Huazhong University of Science and Technology, Tongji Medical CollegeNo. 13 Hangkong Lu, Hankou, Wuhan 430030, Hubei, PR China
| | - Hongmei Dong
- Department of Forensic Medicine, Huazhong University of Science and Technology, Tongji Medical CollegeNo. 13 Hangkong Lu, Hankou, Wuhan 430030, Hubei, PR China
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66
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Bai S, Mao M, Tian L, Yu Y, Zeng J, Ouyang K, Yu L, Li L, Wang D, Deng X, Wei C, Luo Y. Calcium sensing receptor mediated the excessive generation of β-amyloid peptide induced by hypoxia in vivo and in vitro. Biochem Biophys Res Commun 2015; 459:568-73. [DOI: 10.1016/j.bbrc.2015.02.141] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 02/24/2015] [Indexed: 02/08/2023]
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Matsushita T, Madireddy L, Sprenger T, Khankhanian P, Magon S, Naegelin Y, Caverzasi E, Lindberg RLP, Kappos L, Hauser SL, Oksenberg JR, Henry R, Pelletier D, Baranzini SE. Genetic associations with brain cortical thickness in multiple sclerosis. GENES BRAIN AND BEHAVIOR 2015; 14:217-27. [PMID: 25684059 DOI: 10.1111/gbb.12190] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 11/25/2014] [Accepted: 11/27/2014] [Indexed: 02/04/2023]
Abstract
Multiple sclerosis (MS) is characterized by temporal and spatial dissemination of demyelinating lesions in the central nervous system. Associated neurodegenerative changes contributing to disability have been recognized even at early disease stages. Recent studies show the importance of gray matter damage for the accrual of clinical disability rather than white matter where demyelination is easily visualized by magnetic resonance imaging (MRI). The susceptibility to MS is influenced by genetic risk, but genetic factors associated with the disability are not known. We used MRI data to determine cortical thickness in 557 MS cases and 75 controls and in another cohort of 219 cases. We identified nine areas showing different thickness between cases and controls (regions of interest, ROI) (eight of them were negatively correlated with Kurtzke's expanded disability status scale, EDSS) and conducted genome-wide association studies (GWAS) in 464 and 211 cases available from the two data sets. No marker exceeded genome-wide significance in the discovery cohort. We next combined nominal statistical evidence of association with physical evidence of interaction from a curated human protein interaction network, and searched for subnetworks enriched with nominally associated genes and for commonalities between the two data sets. This network-based pathway analysis of GWAS detected gene sets involved in glutamate signaling, neural development and an adjustment of intracellular calcium concentration. We report here for the first time gene sets associated with cortical thinning of MS. These genes are potentially correlated with disability of MS.
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Affiliation(s)
- T Matsushita
- Department of Neurology, University of California, San Francisco, CA, USA
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68
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Qu L. Neuronal Fc gamma receptor I as a novel mediator for IgG immune complex-induced peripheral sensitization. Neural Regen Res 2015; 7:2075-9. [PMID: 25624839 PMCID: PMC4296428 DOI: 10.3969/j.issn.1673-5374.2012.26.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Accepted: 06/30/2012] [Indexed: 12/23/2022] Open
Abstract
Chronic pain often accompanies immune-related diseases with an elevated level of IgG immune complex (IgG-IC) in the serum and/or the affected tissues though the underlying mechanisms are largely unknown. Fc gamma receptors (FcγRs), known as the receptors for the Fc domain of immunoglobulin G (IgG), are typically expressed on immune cells. A general consensus is that the activation of FcγRs by IgG-IC in such immune cells induces the release of proinflammatory cytokines from the immune cells, which may contribute to the IgG-IC-mediated peripheral sensitization. In addition to the immune cells, recent studies have revealed that FcγRI, but not FcγRII and FcγRIII, is also expressed in a subpopulation of primary sensory neurons. Moreover, IgG-IC directly excites the primary sensory neurons through neuronal FcγRI. These findings indicate that neuronal FcγRI provides a novel direct linkage between immunoglobulin and primary sensory neurons, which may be a novel target for the treatment of pain in the immune-related disorders. In this review, we summarize the expression pattern, functions, and the associated cellular signaling of FcγRs in the primary sensory neurons.
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Affiliation(s)
- Lintao Qu
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06510, USA
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69
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Bando Y, Nomura T, Bochimoto H, Murakami K, Tanaka T, Watanabe T, Yoshida S. Abnormal morphology of myelin and axon pathology in murine models of multiple sclerosis. Neurochem Int 2015; 81:16-27. [PMID: 25595039 DOI: 10.1016/j.neuint.2015.01.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 01/09/2015] [Accepted: 01/12/2015] [Indexed: 11/29/2022]
Abstract
Demyelination and axonal damage are responsible for neurological deficits in multiple sclerosis (MS), an inflammatory demyelinating disease of the central nervous system. However, the pathology of axonal damage in MS is not fully understood. In this study, histological analysis of morphological changes of axonal organelles during demyelination in murine models was investigated by scanning electron microscopy (SEM) using an osmium-maceration method. In cuprizone-induced demyelination, SEM showed typical morphology of demyelination in the corpus callosum of mouse brain. In contrast, SEM displayed variations in ultrastructural abnormalities of myelin structures and axonal organelles in spinal cord white matter of experimental autoimmune encephalomyelitis (EAE) mice, an animal model of MS. Myelin detachment and excessive myelin formation were observed as typical morphological myelin abnormalities in EAE. In addition, well-developed axoplasmic reticulum-like structures and accumulated mitochondria were observed in tortuous degenerating/degenerated axons and the length of mitochondria in axons of EAE spinal cord was shorter compared with naïve spinal cord. Immunohistochemistry also revealed dysfunction of mitochondrial fusion/fission machinery in EAE spinal cord axons. Moreover, the number of Y-shaped mitochondria was significantly increased in axons of the EAE spinal cord. Axonal morphologies in myelin basic protein-deficient shiverer mice were similar to those in EAE. However, shiverer mice had "tortuous" (S-curve shaped mitochondria) and larger mitochondria compared with wild-type and EAE mice. Lastly, analysis of human MS patient autopsied brains also demonstrated abnormal myelin structures in demyelinating lesions. These results indicate that morphological abnormalities of myelin and axonal organelles play important role on the pathogenesis of axonal injury in demyelinating diseases.
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Affiliation(s)
- Yoshio Bando
- Department of Functional Anatomy and Neuroscience, Asahikawa Medical University, Asahikawa 078-8510, Japan.
| | - Taichi Nomura
- Department of Functional Anatomy and Neuroscience, Asahikawa Medical University, Asahikawa 078-8510, Japan
| | - Hiroki Bochimoto
- Department of Microscopic Anatomy and Cell Biology, Asahikawa Medical University, Asahikawa 078-8510, Japan
| | - Koichi Murakami
- Department of Functional Anatomy and Neuroscience, Asahikawa Medical University, Asahikawa 078-8510, Japan
| | - Tatsuhide Tanaka
- Department of Functional Anatomy and Neuroscience, Asahikawa Medical University, Asahikawa 078-8510, Japan
| | - Tsuyoshi Watanabe
- Department of Microscopic Anatomy and Cell Biology, Asahikawa Medical University, Asahikawa 078-8510, Japan
| | - Shigetaka Yoshida
- Department of Functional Anatomy and Neuroscience, Asahikawa Medical University, Asahikawa 078-8510, Japan
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70
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JSAP1/JIP3 and JLP regulate kinesin-1-dependent axonal transport to prevent neuronal degeneration. Cell Death Differ 2015; 22:1260-74. [PMID: 25571974 DOI: 10.1038/cdd.2014.207] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 11/04/2014] [Accepted: 11/10/2014] [Indexed: 11/08/2022] Open
Abstract
Axonal transport is critical for neuronal development and function, and defective axonal transport has been implicated in neurodegenerative diseases. However, how axonal transport is regulated, or how defective transport leads to neuronal degeneration, remains unclear. Here, we report that c-Jun NH2-terminal kinase (JNK)/stress-activated protein kinase-associated protein 1 (JSAP1, also known as JNK-interacting protein 3 (JIP3)) and JNK-associated leucine zipper protein (JLP) are essential for postnatal brain development. Mice with a double-knockout (dKO) in Jsap1 and Jlp in the dorsal telencephalon developed progressive neuron loss. Using a primary neuron culture system with induced disruption of targeted genes, combined with gene rescue experiments, we show that JSAP1 and JLP regulate kinesin-1-dependent axonal transport with functional redundancy. We also show that the binding of JSAP1 and JLP to kinesin-1 heavy chain is crucial for interactions between kinesin-1 and microtubules. Furthermore, we describe a molecular mechanism by which defective kinesin-1-dependent axonal transport in Jsap1:Jlp dKO neurons causes axonal degeneration and subsequent neuronal death. JNK hyperactivation because of increased intra-axonal Ca(2+) in the Jsap1:Jlp dKO neurons was found to mediate both the axonal degeneration and neuronal death, in cooperation with the Ca(2+)-dependent protease calpain. Our results indicate that axonal JNK may relocate to the nucleus in a dynein-dependent manner, where it activates the transcription factor c-Jun, resulting in neuronal death. Taken together, our data establish JSAP1 and JLP as positive regulators of kinesin-1-dependent axonal transport, which prevents neuronal degeneration.
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71
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Fregnan F, Muratori L, Simões AR, Giacobini-Robecchi MG, Raimondo S. Role of inflammatory cytokines in peripheral nerve injury. Neural Regen Res 2014; 7:2259-66. [PMID: 25538747 PMCID: PMC4268726 DOI: 10.3969/j.issn.1673-5374.2012.29.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 07/10/2012] [Indexed: 12/22/2022] Open
Abstract
Inflammatory events occurring in the distal part of an injured peripheral nerve have, nowadays, a great resonance. Investigating the timing of action of the several cytokines in the important stages of Wallerian degeneration helps to understand the regenerative process and design pharmacologic intervention that promotes and expedites recovery. The complex and synergistic action of inflammatory cytokines finally promotes axonal regeneration. Cytokines can be divided into pro- and anti-inflammatory cytokines that upregulate and downregulate, respectively, the production of inflammatory mediators. While pro-inflammatory cytokines are expressed in the first phase of Wallerian degeneration and promote the recruitment of macrophages, anti-inflammatory cytokines are expressed after this recruitment and downregulate the production of all cytokines, thus determining the end of the process. In this review, we describe the major inflammatory cytokines involved in Wallerian degeneration and the early phases of nerve regeneration. In particular, we focus on interleukin-1, interleukin-2, interleukin-6, tumor necrosis factor-β, interleukin-10 and transforming growth factor-β.
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Affiliation(s)
- Federica Fregnan
- Department of Clinical and Biological Sciences, University of Turin, Orbassano 10043, Turin, Italy ; Neuroscience Institute of the "Cavalieri Ottolenghi" Foundation, Orbassano 10043, Turin, Italy
| | - Luisa Muratori
- Department of Clinical and Biological Sciences, University of Turin, Orbassano 10043, Turin, Italy ; Neuroscience Institute of the "Cavalieri Ottolenghi" Foundation, Orbassano 10043, Turin, Italy
| | - Anabel Rodriguez Simões
- Department of Clinical and Biological Sciences, University of Turin, Orbassano 10043, Turin, Italy
| | | | - Stefania Raimondo
- Department of Clinical and Biological Sciences, University of Turin, Orbassano 10043, Turin, Italy ; Neuroscience Institute of the "Cavalieri Ottolenghi" Foundation, Orbassano 10043, Turin, Italy
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72
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Williams PR, Marincu BN, Sorbara CD, Mahler CF, Schumacher AM, Griesbeck O, Kerschensteiner M, Misgeld T. A recoverable state of axon injury persists for hours after spinal cord contusion in vivo. Nat Commun 2014; 5:5683. [PMID: 25511170 DOI: 10.1038/ncomms6683] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2014] [Accepted: 10/28/2014] [Indexed: 01/25/2023] Open
Abstract
Therapeutic strategies for spinal cord injury (SCI) commonly focus on regenerating disconnected axons. An alternative approach would be to maintain continuity of damaged axons, especially after contusion. The viability of such neuropreservative strategies depends on the degree to which initially injured axons can recover. Here we use morphological and molecular in vivo imaging after contusion SCI in mice to show that injured axons persist in a metastable state for hours. Intra-axonal calcium dynamics influence fate, but the outcome is not invariably destructive in that many axons with calcium elevations recover homeostasis without intervention. Calcium enters axons primarily through mechanopores. Spontaneous pore resealing allows calcium levels to normalize and axons to survive long term. Axon loss can be halted by blocking calcium influx or calpain, even with delayed initiation. Our data identify an inherent self-preservation process in contused axons and a window of opportunity for rescuing connectivity after nontransecting SCI.
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Affiliation(s)
- Philip R Williams
- Institute of Neuronal Cell Biology, Technische Universität München, Munich 80802, Germany
| | - Bogdan-Nicolae Marincu
- Institute of Neuronal Cell Biology, Technische Universität München, Munich 80802, Germany
| | - Catherine D Sorbara
- 1] Institute of Neuronal Cell Biology, Technische Universität München, Munich 80802, Germany [2] Institute of Clinical Neuroimmunology, Ludwig-Maximilians Universität München, Munich 81377, Germany
| | - Christoph F Mahler
- Institute of Clinical Neuroimmunology, Ludwig-Maximilians Universität München, Munich 81377, Germany
| | - Adrian-Minh Schumacher
- Institute of Clinical Neuroimmunology, Ludwig-Maximilians Universität München, Munich 81377, Germany
| | - Oliver Griesbeck
- Max-Planck Institute of Neurobiology, Martinsried 82152, Germany
| | - Martin Kerschensteiner
- 1] Institute of Clinical Neuroimmunology, Ludwig-Maximilians Universität München, Munich 81377, Germany [2] Munich Cluster for Systems Neurology (SyNergy), Munich 81377, Germany
| | - Thomas Misgeld
- 1] Institute of Neuronal Cell Biology, Technische Universität München, Munich 80802, Germany [2] Munich Cluster for Systems Neurology (SyNergy), Munich 81377, Germany [3] Center of Integrated Protein Science (CIPSM), Munich 81377, Germany [4] German Center for Neurodegenerative Diseases (DZNE), Munich 81377, Germany
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73
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Okada SLM, Stivers NS, Stys PK, Stirling DP. An ex vivo laser-induced spinal cord injury model to assess mechanisms of axonal degeneration in real-time. J Vis Exp 2014:e52173. [PMID: 25490396 DOI: 10.3791/52173] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
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 structures. Here, we describe how to isolate and image the living spinal cord from mice to capture dynamics of acute axonal injury.
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Affiliation(s)
- Starlyn L M Okada
- KY Spinal Cord Injury Research Center, Department of Neurological Surgery, University of Louisville
| | - Nicole S Stivers
- KY Spinal Cord Injury Research Center, Department of Neurological Surgery, University of Louisville
| | - Peter K Stys
- Hotchkiss Brain Institute, Department of Clinical Neurosciences, University of Calgary
| | - David P Stirling
- KY Spinal Cord Injury Research Center, Department of Neurological Surgery, University of Louisville;
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74
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Pease SE, Segal RA. Preserve and protect: maintaining axons within functional circuits. Trends Neurosci 2014; 37:572-82. [PMID: 25167775 DOI: 10.1016/j.tins.2014.07.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 07/21/2014] [Accepted: 07/27/2014] [Indexed: 12/14/2022]
Abstract
During development, neural circuits are initially generated by exuberant innervation and are rapidly refined by selective preservation and elimination of axons. The establishment and maintenance of functional circuits therefore requires coordination of axon survival and degeneration pathways. Both developing and mature circuits rely on interdependent mitochondrial and cytoskeletal components to maintain axonal health and homeostasis; injury or diseases that impinge on these components frequently cause pathologic axon loss. Here, we review recent findings that identify mechanisms of axonal preservation in the contexts of development, injury, and disease.
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Affiliation(s)
- Sarah E Pease
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Rosalind A Segal
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA.
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75
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Goncharenko K, Eftekharpour E, Velumian AA, Carlen PL, Fehlings MG. Changes in gap junction expression and function following ischemic injury of spinal cord white matter. J Neurophysiol 2014; 112:2067-75. [PMID: 25080569 DOI: 10.1152/jn.00037.2013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Gap junctions are widely present in spinal cord white matter; however, their role in modulating the dynamics of axonal dysfunction remains largely unexplored. We hypothesized that inhibition of gap junctions reduces the loss of axonal function during oxygen and glucose deprivation (OGD). The functional role of gap junctions was assessed by electrophysiological recordings of compound action potentials (CAPs) in Wistar rat spinal cord slices with the sucrose gap technique. The in vitro slices were subjected to 30-min OGD. Gap junction connexin (Cx) mRNA expression was determined by qPCR and normalized to β-actin. A 30-min OGD resulted in reduction of CAPs to 14.8 ± 4.6% of their pre-OGD amplitude (n = 5). In the presence of gap junction blockers carbenoxolone (Cbx; 100 μM) and 1-octanol (Oct; 300 μM), the CAP reduction in OGD was to only 35.7 ± 5.7% of pre-OGD amplitude in Cbx (n = 9) and to 37.4 ± 8.9% of pre-OGD amplitude in Oct (n = 10). Both drugs also noticeably prolonged the half-decline time of CAP amplitudes in OGD from 6.0 min in no-drug conditions to 9.6 min in the presence of Cbx and to 7.7 min in the presence of Oct, suggesting that blocking gap junctions reduces conduction loss during OGD. With application of Cbx and Oct in the setting of OGD, expression of Cx30 and Cx43 mRNA was downregulated. Our data provide new insights into the role of gap junctions in white matter ischemia and reveal the necessity of a cautious approach in determining detrimental or beneficial effects of gap junction blockade in white matter ischemia.
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Affiliation(s)
- Karina Goncharenko
- Division of Neurosurgery and Division of Genetics and Development, Toronto Western Research Institute, Krembil Neuroscience Centre, University Health Network and University of Toronto, Toronto, Ontario, Canada; Departments of Physiology and
| | - Eftekhar Eftekharpour
- Division of Neurosurgery and Division of Genetics and Development, Toronto Western Research Institute, Krembil Neuroscience Centre, University Health Network and University of Toronto, Toronto, Ontario, Canada
| | - Alexander A Velumian
- Division of Neurosurgery and Division of Genetics and Development, Toronto Western Research Institute, Krembil Neuroscience Centre, University Health Network and University of Toronto, Toronto, Ontario, Canada; Departments of Physiology and Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Peter L Carlen
- Division of Neurosurgery and Division of Genetics and Development, Toronto Western Research Institute, Krembil Neuroscience Centre, University Health Network and University of Toronto, Toronto, Ontario, Canada; Departments of Physiology and
| | - Michael G Fehlings
- Division of Neurosurgery and Division of Genetics and Development, Toronto Western Research Institute, Krembil Neuroscience Centre, University Health Network and University of Toronto, Toronto, Ontario, Canada; Surgery, University of Toronto, Toronto, Ontario, Canada
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76
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Fern RF, Matute C, Stys PK. White matter injury: Ischemic and nonischemic. Glia 2014; 62:1780-9. [PMID: 25043122 DOI: 10.1002/glia.22722] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 06/18/2014] [Accepted: 06/30/2014] [Indexed: 02/02/2023]
Abstract
Ischemic pathologies of white matter (WM) include a large proportion of stroke and developmental lesions while multiple sclerosis (MS) is the archetype nonischemic pathology. Growing evidence suggests other important diseases including neurodegenerative and psychiatric disorders also involve a significant WM component. Axonal, oligodendroglial, and astroglial damage proceed via distinct mechanisms in ischemic WM and these mechanisms evolve dramatically with maturation. Axons may pass through four developmental stages where the pattern of membrane protein expression influences how the structure responds to ischemia; WM astrocytes pass through at least two and differ significantly in their ischemia tolerance from grey matter astrocytes; oligodendroglia pass through at least three, with the highly ischemia intolerant pre-oligodendrocyte (pre-Oli) stage linking the less sensitive precursor and mature phenotypes. Neurotransmitters play a central role in WM pathology at all ages. Glutamate excitotoxicity in WM has both necrotic and apoptotic components; the latter mediated by intracellular pathways which differ between receptor types. ATP excitotoxicity may be largely mediated by the P2X7 receptor and also has both necrotic and apoptotic components. Interplay between microglia and other cell types is a critical element in the injury process. A growing appreciation of the significance of WM injury for nonischemic neurological disorders is currently stimulating research into mechanisms; with curious similarities being found with those operating during ischemia. A good example is traumatic brain injury, where axonal pathology can proceed via almost identical pathways to those described during acute ischemia.
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Affiliation(s)
- Robert F Fern
- Peninsula School of Medicine and Dentistry, University of Plymouth, United Kingdom
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77
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Butt AM, Fern RF, Matute C. Neurotransmitter signaling in white matter. Glia 2014; 62:1762-79. [PMID: 24753049 DOI: 10.1002/glia.22674] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 03/04/2014] [Accepted: 03/31/2014] [Indexed: 12/16/2022]
Abstract
White matter (WM) tracts are bundles of myelinated axons that provide for rapid communication throughout the CNS and integration in grey matter (GM). The main cells in myelinated tracts are oligodendrocytes and astrocytes, with small populations of microglia and oligodendrocyte precursor cells. The prominence of neurotransmitter signaling in WM, which largely exclude neuronal cell bodies, indicates it must have physiological functions other than neuron-to-neuron communication. A surprising aspect is the diversity of neurotransmitter signaling in WM, with evidence for glutamatergic, purinergic (ATP and adenosine), GABAergic, glycinergic, adrenergic, cholinergic, dopaminergic and serotonergic signaling, acting via a wide range of ionotropic and metabotropic receptors. Both axons and glia are potential sources of neurotransmitters and may express the respective receptors. The physiological functions of neurotransmitter signaling in WM are subject to debate, but glutamate and ATP-mediated signaling have been shown to evoke Ca(2+) signals in glia and modulate axonal conduction. Experimental findings support a model of neurotransmitters being released from axons during action potential propagation acting on glial receptors to regulate the homeostatic functions of astrocytes and myelination by oligodendrocytes. Astrocytes also release neurotransmitters, which act on axonal receptors to strengthen action potential propagation, maintaining signaling along potentially long axon tracts. The co-existence of multiple neurotransmitters in WM tracts suggests they may have diverse functions that are important for information processing. Furthermore, the neurotransmitter signaling phenomena described in WM most likely apply to myelinated axons of the cerebral cortex and GM areas, where they are doubtless important for higher cognitive function.
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Affiliation(s)
- Arthur M Butt
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, United Kingdom
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78
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Back SA, Rosenberg PA. Pathophysiology of glia in perinatal white matter injury. Glia 2014; 62:1790-815. [PMID: 24687630 DOI: 10.1002/glia.22658] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 02/13/2014] [Accepted: 02/27/2014] [Indexed: 12/12/2022]
Abstract
Injury to the preterm brain has a particular predilection for cerebral white matter. White matter injury (WMI) is the most common cause of brain injury in preterm infants and a major cause of chronic neurological morbidity including cerebral palsy. Factors that predispose to WMI include cerebral oxygenation disturbances and maternal-fetal infection. During the acute phase of WMI, pronounced oxidative damage occurs that targets late oligodendrocyte progenitors (pre-OLs). The developmental predilection for WMI to occur during prematurity appears to be related to both the timing of appearance and regional distribution of susceptible pre-OLs that are vulnerable to a variety of chemical mediators including reactive oxygen species, glutamate, cytokines, and adenosine. During the chronic phase of WMI, the white matter displays abberant regeneration and repair responses. Early OL progenitors respond to WMI with a rapid robust proliferative response that results in a several fold regeneration of pre-OLs that fail to terminally differentiate along their normal developmental time course. Pre-OL maturation arrest appears to be related in part to inhibitory factors that derive from reactive astrocytes in chronic lesions. Recent high field magnetic resonance imaging (MRI) data support that three distinct forms of chronic WMI exist, each of which displays unique MRI and histopathological features. These findings suggest the possibility that therapies directed at myelin regeneration and repair could be initiated early after WMI and monitored over time. These new mechanisms of acute and chronic WMI provide access to a variety of new strategies to prevent or promote repair of WMI in premature infants.
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Affiliation(s)
- Stephen A Back
- Department of Pediatrics, Oregon Health and Science University, Portland, Oregon; Department of Neurology, Oregon Health and Science University, Portland, Oregon
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79
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Abstract
Multiple sclerosis (MS) is the most frequent chronic inflammatory disease of the CNS, and imposes major burdens on young lives. Great progress has been made in understanding and moderating the acute inflammatory components of MS, but the pathophysiological mechanisms of the concomitant neurodegeneration--which causes irreversible disability--are still not understood. Chronic inflammatory processes that continuously disturb neuroaxonal homeostasis drive neurodegeneration, so the clinical outcome probably depends on the balance of stressor load (inflammation) and any remaining capacity for neuronal self-protection. Hence, suitable drugs that promote the latter state are sorely needed. With the aim of identifying potential novel therapeutic targets in MS, we review research on the pathological mechanisms of neuroaxonal dysfunction and injury, such as altered ion channel activity, and the endogenous neuroprotective pathways that counteract oxidative stress and mitochondrial dysfunction. We focus on mechanisms inherent to neurons and their axons, which are separable from those acting on inflammatory responses and might, therefore, represent bona fide neuroprotective drug targets with the capability to halt MS progression.
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80
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Stirling DP, Cummins K, Wayne Chen SR, Stys P. Axoplasmic reticulum Ca(2+) release causes secondary degeneration of spinal axons. Ann Neurol 2014; 75:220-9. [PMID: 24395428 DOI: 10.1002/ana.24099] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 11/29/2013] [Accepted: 12/26/2013] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Transected axons of the central nervous system fail to regenerate and instead die back away from the lesion site, resulting in permanent disability. Although both intrinsic (eg, microtubule instability, calpain activation) and extrinsic (ie, macrophages) processes are implicated in axonal dieback, the underlying mechanisms remain uncertain. Furthermore, the precise mechanisms that cause delayed "bystander" loss of spinal axons, that is, ones that were not directly damaged by the initial insult, but succumbed to secondary degeneration, remain unclear. Our goal was to evaluate the role of intra-axonal Ca(2+) stores in secondary axonal degeneration following spinal cord injury. METHODS We developed a 2-photon laser-induced spinal cord injury model to follow morphological and Ca(2+) changes in live myelinated spinal axons acutely following injury. RESULTS Transected axons "died back" within swollen myelin or underwent synchronous pan-fragmentation associated with robust Ca(2+) increases. Spared fibers underwent delayed secondary bystander degeneration. Reducing Ca(2+) release from axonal stores mediated by ryanodine and inositol triphosphate receptors significantly decreased axonal dieback and bystander injury. Conversely, a gain-of-function ryanodine receptor 2 mutant or pharmacological treatments that promote axonal store Ca(2+) release worsened these events. INTERPRETATION Ca(2+) release from intra-axonal Ca(2+) stores, distributed along the length of the axon, contributes significantly to secondary degeneration of axons. This refocuses our approach to protecting spinal white matter tracts, where emphasis has been placed on limiting Ca(2+) entry from the extracellular space across cell membranes, and emphasizes that modulation of axonal Ca(2+) stores may be a key pharmacotherapeutic goal in spinal cord injury.
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Affiliation(s)
- David P Stirling
- Department of Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Kentucky Spinal Cord Injury Research Center and Departments of Neurological Surgery, Microbiology and Immunology, University of Louisville, Louisville, KY
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81
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Sodium channels contribute to degeneration of dorsal root ganglion neurites induced by mitochondrial dysfunction in an in vitro model of axonal injury. J Neurosci 2014; 33:19250-61. [PMID: 24305821 DOI: 10.1523/jneurosci.2148-13.2013] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Axonal degeneration occurs in multiple neurodegenerative disorders of the central and peripheral nervous system. Although the underlying molecular pathways leading to axonal degeneration are incompletely understood, accumulating evidence suggests contributions of impaired mitochondrial function, disrupted axonal transport, and/or dysfunctional intracellular Ca(2+)-homeostasis in the injurious cascade associated with axonal degeneration. Utilizing an in vitro model of axonal degeneration, we studied a subset of mouse peripheral sensory neurons in which neurites were exposed selectively to conditions associated with the pathogenesis of axonal neuropathies in vivo. Rotenone-induced mitochondrial dysfunction resulted in neurite degeneration accompanied by reduced ATP levels and increased ROS levels in neurites. Blockade of voltage-gated sodium channels with TTX and reverse (Ca(2+)-importing) mode of the sodium-calcium exchanger (NCX) with KB-R7943 partially protected rotenone-treated neurites from degeneration, suggesting a contribution of sodium channels and reverse NCX activity to the degeneration of neurites resulting from impaired mitochondrial function. Pharmacological inhibition of the Na(+)/K(+)-ATPase with ouabain induced neurite degeneration, which was attenuated by TTX and KB-R7943, supporting a contribution of sodium channels in axonal degenerative pathways accompanying impaired Na(+)/K(+)-ATPase activity. Conversely, oxidant stress (H2O2)-induced neurite degeneration was not attenuated by TTX. Our results demonstrate that both energetic and oxidative stress targeted selectively to neurites induces neurite degeneration and that blockade of sodium channels and of reverse NCX activity blockade partially protects neurites from injury due to energetic stress, but not from oxidative stress induced by H2O2.
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82
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Lozić I, Bartlett CA, Shaw JA, Iyer KS, Dunlop SA, Kilburn MR, Fitzgerald M. Changes in subtypes of Ca microdomains following partial injury to the central nervous system. Metallomics 2014; 6:455-64. [PMID: 24425149 DOI: 10.1039/c3mt00336a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Rapid changes in Ca(2+) concentration and location in response to injury play key roles in a range of biological systems. However, quantitative analysis of changes in size and distribution of Ca(2+) microdomains in specific cell types in whole tissue samples has been limited by analytical resolution and reliance on indirect Ca(2+) indicator systems. Here, we combine the unique advantages of nanoscale secondary ion mass spectrometry (NanoSIMS) with immunohistochemistry to directly quantify changes in number, size and intensity of Ca microdomains specific to axonal or glial regions vulnerable to spreading damage following neurotrauma. Furthermore, using NanoSIMS allows separate quantification of Ca microdomains according to their co-localization with areas enriched in P. We rapidly excise and cryopreserve optic nerve segments from adult rat at time points ranging from 5 minutes to 3 months after injury, allowing assessment of Ca microdomains dynamics with minimal disruption due to tissue processing. We demonstrate significantly more non-P co-localized Ca microdomains in glial than axonal regions in normal optic nerve. The density of Ca microdomains not co-localized with areas enriched in P rapidly, selectively and significantly decreases after injury; densities of Ca microdomains co-localized with P enriched areas are unchanged. An efflux of Ca(2+) from microdomains not co-localized with P may contribute to the structural and functional deficits observed in nerve vulnerable to spreading damage following neurotrauma. NanoSIMS analyses of Ca microdomains allow quantitative and novel insights into Ca dynamics, applicable to a range of normal, as well as diseased or injured mammalian systems.
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Affiliation(s)
- Ivan Lozić
- BioNano, School of Chemistry and Biochemistry, The University of Western Australia, 35 Stirling Hwy, Crawley WA 6009, Australia
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83
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Abstract
The extensive lengths of neuronal processes necessitate efficient mechanisms for communication with the cell body. Neuronal regeneration after nerve injury requires new transcription; thus, long-distance retrograde signalling from axonal lesion sites to the soma and nucleus is required. In recent years, considerable progress has been made in elucidating the mechanistic basis of this system. This has included the discovery of a priming role for early calcium waves; confirmation of central roles for mitogen-activated protein kinase signalling effectors, the importin family of nucleocytoplasmic transport factors and molecular motors such as dynein; and demonstration of the importance of local translation as a key regulatory mechanism. These recent findings provide a coherent mechanistic framework for axon-soma communication in the injured nerve and shed light on the integration of cytoplasmic and nuclear transport in all eukaryotic cells.
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Affiliation(s)
- Ida Rishal
- Department of Biological Chemistry, Weizmann Institute of Science, 76100 Rehovot, Israel
| | - Mike Fainzilber
- Department of Biological Chemistry, Weizmann Institute of Science, 76100 Rehovot, Israel
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84
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Li S, Yang L, Selzer ME, Hu Y. Neuronal endoplasmic reticulum stress in axon injury and neurodegeneration. Ann Neurol 2013; 74:768-77. [PMID: 23955583 PMCID: PMC3963272 DOI: 10.1002/ana.24005] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 08/04/2013] [Accepted: 08/07/2013] [Indexed: 12/13/2022]
Abstract
Injuries to central nervous system axons result not only in Wallerian degeneration of the axon distal to the injury, but also in death or atrophy of the axotomized neurons, depending on injury location and neuron type. No method of permanently avoiding these changes has been found, despite extensive knowledge concerning mechanisms of secondary neuronal injury. The autonomous endoplasmic reticulum (ER) stress pathway in neurons has recently been implicated in retrograde neuronal degeneration. In addition to the emerging role of ER morphology in axon maintenance, we propose that ER stress is a common neuronal response to disturbances in axon integrity and a general mechanism for neurodegeneration. Thus, manipulation of the ER stress pathway could have important therapeutic implications for neuroprotection.
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Affiliation(s)
- Shaohua Li
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Temple University School of Medicine, Philadelphia, PA, USA
- Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
| | - Liu Yang
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Temple University School of Medicine, Philadelphia, PA, USA
| | - Michael E. Selzer
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Temple University School of Medicine, Philadelphia, PA, USA
- Department of Neurology, Temple University School of Medicine, Philadelphia, PA, USA
| | - Yang Hu
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Temple University School of Medicine, Philadelphia, PA, USA
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85
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Franssen H, Straver DC. Pathophysiology of immune-mediated demyelinating neuropathies-part I: Neuroscience. Muscle Nerve 2013; 48:851-64. [DOI: 10.1002/mus.24070] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/26/2013] [Indexed: 11/09/2022]
Affiliation(s)
- Hessel Franssen
- Department of Neurology, Section Neuromuscular Disorders, F02.230, Rudolf Magnus Institute for Neuroscience; University Medical Center Utrecht; Heidelberglaan 100, 3584 CX Utrecht The Netherlands
| | - Dirk C.G. Straver
- Department of Neurology, Section Neuromuscular Disorders, F02.230, Rudolf Magnus Institute for Neuroscience; University Medical Center Utrecht; Heidelberglaan 100, 3584 CX Utrecht The Netherlands
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86
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Jeter CB, Hergenroeder GW, Hylin MJ, Redell JB, Moore AN, Dash PK. Biomarkers for the diagnosis and prognosis of mild traumatic brain injury/concussion. J Neurotrauma 2013; 30:657-70. [PMID: 23062081 DOI: 10.1089/neu.2012.2439] [Citation(s) in RCA: 156] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Mild traumatic brain injury (mTBI) results from a transfer of mechanical energy into the brain from traumatic events such as rapid acceleration/deceleration, a direct impact to the head, or an explosive blast. Transfer of energy into the brain can cause structural, physiological, and/or functional changes in the brain that may yield neurological, cognitive, and behavioral symptoms that can be long-lasting. Because mTBI can cause these symptoms in the absence of positive neuroimaging findings, its diagnosis can be subjective and often is based on self-reported neurological symptoms. Further, proper diagnosis can be influenced by the motivation to conceal or embellish signs and/or an inability of the patient to notice subtle dysfunctions or alterations of consciousness. Therefore, appropriate diagnosis of mTBI would benefit from objective indicators of injury. Concussion and mTBI are often used interchangeably, with concussion being primarily used in sport medicine, whereas mTBI is used in reference to traumatic injury. This review provides a critical assessment of the status of current biomarkers for the diagnosis of human mTBI. We review the status of biomarkers that have been tested in TBI patients with injuries classified as mild, and introduce a new concept for the discovery of biomarkers (termed symptophenotypes) to predict common and unique symptoms of concussion. Finally, we discuss the need for biomarker/biomarker signatures that can detect mTBI in the context of polytrauma, and to assess the consequences of repeated injury on the development of secondary injury syndrome, prolongation of post-concussion symptoms, and chronic traumatic encephalopathy.
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Affiliation(s)
- Cameron B Jeter
- Department of Diagnostic and Biomedical Sciences, The University of Texas School of Dentistry at Houston, Houston, Texas, USA
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87
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Repair of the Peripheral Nerve-Remyelination that Works. Brain Sci 2013; 3:1182-97. [PMID: 24961524 PMCID: PMC4061866 DOI: 10.3390/brainsci3031182] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 07/07/2013] [Accepted: 07/19/2013] [Indexed: 12/15/2022] Open
Abstract
In this review we summarize the events known to occur after an injury in the peripheral nervous system. We have focused on the Schwann cells, as they are the most important cells for the repair process and facilitate axonal outgrowth. The environment created by this cell type is essential for the outcome of the repair process. The review starts with a description of the current state of knowledge about the initial events after injury, followed by Wallerian degeneration, and subsequent regeneration. The importance of surgical repair, carried out as soon as possible to increase the chances of a good outcome, is emphasized throughout the review. The review concludes by describing the target re-innervation, which today is one of the most serious problems for nerve regeneration. It is clear, compiling this data, that even though regeneration of the peripheral nervous system is possible, more research in this area is needed in order to perfect the outcome.
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88
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Stevens M, Timmermans S, Bottelbergs A, Hendriks JJ, Brône B, Baes M, Tytgat J. Block of a subset of sodium channels exacerbates experimental autoimmune encephalomyelitis. J Neuroimmunol 2013; 261:21-8. [DOI: 10.1016/j.jneuroim.2013.04.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 03/19/2013] [Accepted: 04/11/2013] [Indexed: 10/26/2022]
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89
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Tsutsui S, Stys PK. Metabolic injury to axons and myelin. Exp Neurol 2013; 246:26-34. [DOI: 10.1016/j.expneurol.2012.04.016] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 03/20/2012] [Accepted: 04/23/2012] [Indexed: 12/31/2022]
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90
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Domingo A, Mayoral O, Monterde S, Santafé MM. Neuromuscular damage and repair after dry needling in mice. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE : ECAM 2013; 2013:260806. [PMID: 23662122 PMCID: PMC3638584 DOI: 10.1155/2013/260806] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 02/23/2013] [Accepted: 03/12/2013] [Indexed: 11/23/2022]
Abstract
Objective. Some dry needling treatments involve repetitive and rapid needle insertions into myofascial trigger points. This type of treatment causes muscle injury and can also damage nerve fibers. The aim of this study is to determine the injury caused by 15 repetitive punctures in the muscle and the intramuscular nerves in healthy mouse muscle and its ulterior regeneration. Methods. We repeatedly needled the levator auris longus muscle of mice, and then the muscles were processed with immunohistochemistry, methylene blue, and electron microscopy techniques. Results. Three hours after the dry needling procedure, the muscle fibers showed some signs of an inflammatory response, which progressed to greater intensity 24 hours after the procedure. Some inflammatory cells could still be seen when the muscle regeneration was almost complete seven days after the treatment. One day after the treatment, some changes in the distribution of receptors could be observed in the denervated postsynaptic component. Reinnervation was complete by the third day after the dry needling procedure. We also saw very fine axonal branches reinnervating all the postsynaptic components and some residual sprouts the same day. Conclusion. Repeated dry needling punctures in muscle do not perturb the different stages of muscle regeneration and reinnervation.
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Affiliation(s)
- Ares Domingo
- Unit of Histology and Neurobiology, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Rovira i Virgili University, Carrer St. Llorenç No. 21, 43201 Reus, Spain
| | - Orlando Mayoral
- Physical Therapy Unit, Hospital Provincial de Toledo, Cerro de San Servando s/n, 45006 Toledo, Spain
| | - Sonia Monterde
- Unit of Physiotherapy, Department of Medicine and Surgery, Faculty of Medicine and Health Sciences, Rovira i Virgili University, Carrer St. Llorenç No. 21, 43201 Reus, Spain
| | - Manel M. Santafé
- Unit of Histology and Neurobiology, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Rovira i Virgili University, Carrer St. Llorenç No. 21, 43201 Reus, Spain
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91
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Park JY, Jang SY, Shin YK, Koh H, Suh DJ, Shinji T, Araki T, Park HT. Mitochondrial swelling and microtubule depolymerization are associated with energy depletion in axon degeneration. Neuroscience 2013; 238:258-69. [PMID: 23485808 DOI: 10.1016/j.neuroscience.2013.02.033] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 01/17/2013] [Accepted: 02/15/2013] [Indexed: 01/03/2023]
Abstract
Although mitochondrial dysfunction is intimately related to axonal degeneration following nerve injury, the molecular mechanisms of mitochondrial swelling and its mechanistic relation to axonal degeneration are largely unknown. Previous studies have demonstrated that axonal degeneration in the injured peripheral nerves shows two morphologically distinct phases: (1) A latency period (∼24h), in which the morphology of axonal cytoskeletons seems unchanged, followed by (2) an execution period (36-48h), which shows a catastrophic granular degeneration of most axonal structures in rodent axons. In the present study, we found that, in the sciatic nerve axotomy model, energy failure and microtubule depolymerization occurred during the latency period whereas mitochondrial swelling and neurofilament degradation started in the execution period. The energy repletion with NAD or an NAD/pyruvate mixture inhibited microtubule depolymerization, mitochondrial swelling and axonal degeneration in transected sciatic nerve axons. In addition, microtubule perturbing agents enhanced axonal degeneration and mitochondrial swelling. Extracellular calcium chelation did not affect energy failure, microtubule depolymerization or mitochondrial swelling, but it did prevent neurofilament degradation. These findings suggest that an early disturbance in energy dynamics regardless of mitochondrial swelling might be a key trigger for the initiation of axonal degeneration and that extracellular calcium influx is a late effector for neurofilament degradation.
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Affiliation(s)
- J Y Park
- Department of Physiology, Mitochondria Hub Regulation Center, College of Medicine, Dong-A University, Busan, Republic of Korea
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92
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Yan D, Jin Y. Regulation of DLK-1 kinase activity by calcium-mediated dissociation from an inhibitory isoform. Neuron 2013; 76:534-48. [PMID: 23141066 DOI: 10.1016/j.neuron.2012.08.043] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/31/2012] [Indexed: 01/19/2023]
Abstract
MAPKKK dual leucine zipper-bearing kinases (DLKs) are regulators of synaptic development and axon regeneration. The mechanisms underlying their activation are not fully understood. Here, we show that C. elegans DLK-1 is activated by a Ca(2+)-dependent switch from inactive heteromeric to active homomeric protein complexes. We identify a DLK-1 isoform, DLK-1S, that shares identical kinase and leucine zipper domains with the previously described long isoform DLK-1L but acts to inhibit DLK-1 function by binding to DLK-1L. The switch between homo- or heteromeric DLK-1 complexes is influenced by Ca(2+) concentration. A conserved hexapeptide in the DLK-1L C terminus is essential for DLK-1 activity and is required for Ca(2+) regulation. The mammalian DLK-1 homolog MAP3K13 contains an identical C-terminal hexapeptide and can functionally complement dlk-1 mutants, suggesting that the DLK activation mechanism is conserved. The DLK activation mechanism is ideally suited for rapid and spatially controlled signal transduction in response to axonal injury and synaptic activity.
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Affiliation(s)
- Dong Yan
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
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93
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Matute C, Domercq M, Pérez-Samartín A, Ransom BR. Protecting white matter from stroke injury. Stroke 2012; 44:1204-11. [PMID: 23212168 DOI: 10.1161/strokeaha.112.658328] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Carlos Matute
- Departamento de Neurociencias, Achucarro Basque Center for Neuroscience, and CIBERNED, Universidad del País Vasco, UPV/EHU, E-48940 Leioa, Vizcaya, Spain.
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94
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Schattling B, Steinbach K, Thies E, Kruse M, Menigoz A, Ufer F, Flockerzi V, Brück W, Pongs O, Vennekens R, Kneussel M, Freichel M, Merkler D, Friese MA. TRPM4 cation channel mediates axonal and neuronal degeneration in experimental autoimmune encephalomyelitis and multiple sclerosis. Nat Med 2012; 18:1805-11. [PMID: 23160238 DOI: 10.1038/nm.3015] [Citation(s) in RCA: 146] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 08/24/2012] [Indexed: 12/12/2022]
Abstract
In multiple sclerosis, an inflammatory disease of the central nervous system (CNS), axonal and neuronal loss are major causes for irreversible neurological disability. However, which molecules contribute to axonal and neuronal injury under inflammatory conditions remains largely unknown. Here we show that the transient receptor potential melastatin 4 (TRPM4) cation channel is crucial in this process. TRPM4 is expressed in mouse and human neuronal somata, but it is also expressed in axons in inflammatory CNS lesions in experimental autoimmune encephalomyelitis (EAE) in mice and in human multiple sclerosis tissue. Deficiency or pharmacological inhibition of TRPM4 using the antidiabetic drug glibenclamide resulted in reduced axonal and neuronal degeneration and attenuated clinical disease scores in EAE, but this occurred without altering EAE-relevant immune function. Furthermore, Trpm4(-/-) mouse neurons were protected against inflammatory effector mechanisms such as excitotoxic stress and energy deficiency in vitro. Electrophysiological recordings revealed TRPM4-dependent neuronal ion influx and oncotic cell swelling upon excitotoxic stimulation. Therefore, interference with TRPM4 could translate into a new neuroprotective treatment strategy.
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Affiliation(s)
- Benjamin Schattling
- Forschergruppe Neuroimmunologie, Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
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95
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van Horssen J, Singh S, van der Pol S, Kipp M, Lim JL, Peferoen L, Gerritsen W, Kooi EJ, Witte ME, Geurts JJG, de Vries HE, Peferoen-Baert R, van den Elsen PJ, van der Valk P, Amor S. Clusters of activated microglia in normal-appearing white matter show signs of innate immune activation. J Neuroinflammation 2012; 9:156. [PMID: 22747960 PMCID: PMC3411485 DOI: 10.1186/1742-2094-9-156] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 07/02/2012] [Indexed: 12/03/2022] Open
Abstract
Background In brain tissues from multiple sclerosis (MS) patients, clusters of activated HLA-DR-expressing microglia, also referred to as preactive lesions, are located throughout the normal-appearing white matter. The aim of this study was to gain more insight into the frequency, distribution and cellular architecture of preactive lesions using a large cohort of well-characterized MS brain samples. Methods Here, we document the frequency of preactive lesions and their association with distinct white matter lesions in a cohort of 21 MS patients. Immunohistochemistry was used to gain further insight into the cellular and molecular composition of preactive lesions. Results Preactive lesions were observed in a majority of MS patients (67%) irrespective of disease duration, gender or subtype of disease. Microglial clusters were predominantly observed in the vicinity of active demyelinating lesions and are not associated with T cell infiltrates, axonal alterations, activated astrocytes or blood–brain barrier disruption. Microglia in preactive lesions consistently express interleukin-10 and TNF-α, but not interleukin-4, whereas matrix metalloproteases-2 and −9 are virtually absent in microglial nodules. Interestingly, key subunits of the free-radical-generating enzyme NADPH oxidase-2 were abundantly expressed in microglial clusters. Conclusions The high frequency of preactive lesions suggests that it is unlikely that most of them will progress into full-blown demyelinating lesions. Preactive lesions are not associated with blood–brain barrier disruption, suggesting that an intrinsic trigger of innate immune activation, rather than extrinsic factors crossing a damaged blood–brain barrier, induces the formation of clusters of activated microglia.
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Affiliation(s)
- Jack van Horssen
- Department of Molecular Cell Biology and Immunology/Neuropathology, VU University Medical Center, Van der Boechorststraat 7, 1081, BT, Amsterdam, The Netherlands.
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96
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Abstract
Multiple sclerosis (MS) is considered to be an autoimmune, inflammatory disease of the CNS. In most patients, the disease follows a relapsing-remitting course and is characterized by dynamic inflammatory demyelinating lesions in the CNS. Although on the surface MS may appear consistent with a primary autoimmune disease, questions have been raised as to whether inflammation and/or autoimmunity are really at the root of the disease, and it has been proposed that MS might in fact be a degenerative disorder. We argue that MS may be an 'immunological convolution' between an underlying primary degenerative disorder and the host's aberrant immune response. To better understand this disease, we might need to consider non-inflammatory primary progressive MS as the 'real' MS, with inflammatory forms reflecting secondary, albeit very important, reactions.
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97
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Court FA, Coleman MP. Mitochondria as a central sensor for axonal degenerative stimuli. Trends Neurosci 2012; 35:364-72. [PMID: 22578891 DOI: 10.1016/j.tins.2012.04.001] [Citation(s) in RCA: 154] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 03/19/2012] [Accepted: 04/02/2012] [Indexed: 12/12/2022]
Abstract
Axonal degeneration is a major contributor to neuronal dysfunction in many neurological conditions and has additional roles in development. It can be triggered by divergent stimuli including mechanical, metabolic, infectious, toxic, hereditary and inflammatory stresses. Axonal mitochondria are an important convergence point as regulators of bioenergetic metabolism, reactive oxygen species (ROS), Ca²⁺ homeostasis and protease activation. The challenges likely to render axonal mitochondria more vulnerable than their cellular counterparts are reviewed, including axonal transport, replenishing nuclear-encoded proteins and maintenance of quality control, fusion and fission in locations remote from the cell body. The potential for mitochondria to act as a decision node in axon loss is considered, highlighting the need to understand the biology of axonal mitochondria and their contributions to degenerative mechanisms for novel therapeutic strategies.
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Affiliation(s)
- Felipe A Court
- Millennium Nucleus for Regenerative Biology, Faculty of Biology, Catholic University of Chile, Santiago 8331150, Chile.
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98
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Perez SD, Kozic B, Molinaro CA, Thyagarajan S, Ghamsary M, Lubahn CL, Lorton D, Bellinger DL. Chronically lowering sympathetic activity protects sympathetic nerves in spleens from aging F344 rats. J Neuroimmunol 2012; 247:38-51. [PMID: 22546498 DOI: 10.1016/j.jneuroim.2012.03.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 02/28/2012] [Accepted: 03/28/2012] [Indexed: 10/28/2022]
Abstract
In the present study, we investigated how increased sympathetic tone during middle-age affects the splenic sympathetic neurotransmission. Fifteen-month-old (M) F344 rats received rilmenidine (0, 0.5 or 1.5mg/kg/day, i.p. for 90 days) to lower sympathetic tone. Controls for age were untreated 3 or 18M rats. We report that rilmenidine (1) reduced plasma and splenic norepinephrine concentrations and splenic norepinephrine turnover, and partially reversed the sympathetic nerve loss; and (2) increased β-adrenergic receptor (β-AR) density and β-AR-stimulated cAMP production. Collectively, these findings suggest a protective effect of lowering sympathetic tone on sympathetic nerve integrity, and enhanced sympathetic neurotransmission in secondary immune organs.
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Affiliation(s)
- Sam D Perez
- Department of Physiology & Pharmacology, Loma Linda University, School of Medicine, Loma Linda, CA 92350, USA
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99
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Nickells RW, Howell GR, Soto I, John SWM. Under pressure: cellular and molecular responses during glaucoma, a common neurodegeneration with axonopathy. Annu Rev Neurosci 2012; 35:153-79. [PMID: 22524788 DOI: 10.1146/annurev.neuro.051508.135728] [Citation(s) in RCA: 229] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Glaucoma is a complex neurodegenerative disorder that is expected to affect 80 million people by the end of this decade. Retinal ganglion cells (RGCs) are the most affected cell type and progressively degenerate over the course of the disease. RGC axons exit the eye and enter the optic nerve by passing through the optic nerve head (ONH). The ONH is an important site of initial damage in glaucoma. Higher intraocular pressure (IOP) is an important risk factor for glaucoma, but the molecular links between elevated IOP and axon damage in the ONH are poorly defined. In this review and focusing primarily on the ONH, we discuss recent studies that have contributed to understanding the etiology and pathogenesis of glaucoma. We also identify areas that require further investigation and focus on mechanisms identified in other neurodegenerations that may contribute to RGC dysfunction and demise in glaucoma.
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Affiliation(s)
- Robert W Nickells
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Wisconsin 53706, USA.
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100
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Shen H, Goldberg MP. Creatine pretreatment protects cortical axons from energy depletion in vitro. Neurobiol Dis 2012; 47:184-93. [PMID: 22521466 DOI: 10.1016/j.nbd.2012.03.037] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 03/22/2012] [Accepted: 03/31/2012] [Indexed: 10/28/2022] Open
Abstract
Creatine is a natural nitrogenous guanidino compound involved in bioenergy metabolism. Although creatine has been shown to protect neurons of the central nervous system (CNS) from experimental hypoxia/ischemia, it remains unclear if creatine may also protect CNS axons, and if the potential axonal protection depends on glial cells. To evaluate the direct impact of creatine on CNS axons, cortical axons were cultured in a separate compartment from their somas and proximal neurites using a modified two-compartment culture device. Axons in the axon compartment were subjected to acute energy depletion, an in vitro model of white matter ischemia, by exposure to 6mM sodium azide for 30 min in the absence of glucose and pyruvate. Energy depletion reduced axonal ATP by 65%, depolarized axonal resting potential, and damaged 75% of axons. Application of creatine (10 mM) to both compartments of the culture at 24h prior to energy depletion significantly reduced axonal damage by 50%. In line with the role of creatine in the bioenergy metabolism, this application also alleviated the axonal ATP loss and depolarization. Inhibition of axonal depolarization by blocking sodium influx with tetrodotoxin also effectively reduced the axonal damage caused by energy depletion. Further study revealed that the creatine effect was independent of glial cells, as axonal protection was sustained even when creatine was applied only to the axon compartment (free from somas and glial cells) for as little as 2h. In contrast, application of creatine after energy depletion did not protect axons. The data provide the first evidence that creatine pretreatment may directly protect CNS axons from energy deficiency.
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Affiliation(s)
- Hua Shen
- Hope Center for Neurological Disorders and Department of Neurology, Washington University School of Medicine, Saint Louis, MO 63110, USA.
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