1
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Xie RG, Xu GY, Wu SX, Luo C. Presynaptic glutamate receptors in nociception. Pharmacol Ther 2023; 251:108539. [PMID: 37783347 DOI: 10.1016/j.pharmthera.2023.108539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 08/19/2023] [Accepted: 09/25/2023] [Indexed: 10/04/2023]
Abstract
Chronic pain is a frequent, distressing and poorly understood health problem. Plasticity of synaptic transmission in the nociceptive pathways after inflammation or injury is assumed to be an important cellular basis for chronic, pathological pain. Glutamate serves as the main excitatory neurotransmitter at key synapses in the somatosensory nociceptive pathways, in which it acts on both ionotropic and metabotropic glutamate receptors. Although conventionally postsynaptic, compelling anatomical and physiological evidence demonstrates the presence of presynaptic glutamate receptors in the nociceptive pathways. Presynaptic glutamate receptors play crucial roles in nociceptive synaptic transmission and plasticity. They modulate presynaptic neurotransmitter release and synaptic plasticity, which in turn regulates pain sensitization. In this review, we summarize the latest understanding of the expression of presynaptic glutamate receptors in the nociceptive pathways, and how they contribute to nociceptive information processing and pain hypersensitivity associated with inflammation / injury. We uncover the cellular and molecular mechanisms of presynaptic glutamate receptors in shaping synaptic transmission and plasticity to mediate pain chronicity, which may provide therapeutic approaches for treatment of chronic pain.
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Affiliation(s)
- Rou-Gang Xie
- Department of Neurobiology, Fourth Military Medical University, Xi'an 710032, China.
| | - Guang-Yin Xu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases, Institute of Neuroscience, Soochow University, Suzhou 215123, China
| | - Sheng-Xi Wu
- Department of Neurobiology, Fourth Military Medical University, Xi'an 710032, China.
| | - Ceng Luo
- Department of Neurobiology, Fourth Military Medical University, Xi'an 710032, China.
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2
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Stirling DP. Potential physiological and pathological roles for axonal ryanodine receptors. Neural Regen Res 2023; 18:756-759. [PMID: 36204832 PMCID: PMC9700104 DOI: 10.4103/1673-5374.354512] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 06/02/2022] [Accepted: 06/23/2022] [Indexed: 11/04/2022] Open
Abstract
Clinical disability following trauma or disease to the spinal cord often involves the loss of vital white matter elements including axons and glia. Although excessive Ca2+ is an established driver of axonal degeneration, therapeutically targeting externally sourced Ca2+ to date has had limited success in both basic and clinical studies. Contributing factors that may underlie this limited success include the complexity of the many potential sources of Ca2+ entry and the discovery that axons also contain substantial amounts of stored Ca2+ that if inappropriately released could contribute to axonal demise. Axonal Ca2+ storage is largely accomplished by the axoplasmic reticulum that is part of a continuous network of the endoplasmic reticulum that provides a major sink and source of intracellular Ca2+ from the tips of dendrites to axonal terminals. This "neuron-within-a-neuron" is positioned to rapidly respond to diverse external and internal stimuli by amplifying cytosolic Ca2+ levels and generating short and long distance regenerative Ca2+ waves through Ca2+ induced Ca2+ release. This review provides a glimpse into the molecular machinery that has been implicated in regulating ryanodine receptor mediated Ca2+ release in axons and how dysregulation and/or overstimulation of these internodal axonal signaling nanocomplexes may directly contribute to Ca2+-dependent axonal demise. Neuronal ryanodine receptors expressed in dendrites, soma, and axonal terminals have been implicated in synaptic transmission and synaptic plasticity, but a physiological role for internodal localized ryanodine receptors remains largely obscure. Plausible physiological roles for internodal ryanodine receptors and such an elaborate internodal binary membrane signaling network in axons will also be discussed.
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Affiliation(s)
- David P. Stirling
- Kentucky Spinal Cord Injury Research Center and Departments of Neurological Surgery, Anatomical Sciences and Neurobiology, Microbiology and Immunology, University of Louisville, School of Medicine, Louisville, KY, USA
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3
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Zhang Y, Hu W, Chen D, Ding M, Wang T, Wang Y, Chi J, Li Z, Li Q, Li C. An allergenic plant calmodulin from Artemisia pollen primes human DCs leads to Th2 polarization. Front Immunol 2022; 13:996427. [PMID: 36248805 PMCID: PMC9556433 DOI: 10.3389/fimmu.2022.996427] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Accepted: 09/12/2022] [Indexed: 11/13/2022] Open
Abstract
Artemisia pollen is the major cause of seasonal allergic respiratory diseases in the northern hemisphere. About 28.57% of Artemisia allergic patients’ IgE can recognize ArtCaM, a novel allergenic calmodulin from Artemisia identified in this study. These patients exhibited stronger allergic reactions and a longer duration of allergic symptoms. However, the signaling mechanism that triggers these allergic reactions is not fully understood. In this study, we found that extracellular ArtCaM directly induces the maturation of human dendritic cells (DCs), which is attributed to a series of Ca2+ relevant cascades, including Ca2+/NFAT/CaMKs. ArtCaM alone induces inflammatory response toward Th1, Th17, and Treg. Interestingly, a combination of ArtCaM and anti-ArtCaM IgE led to Th2 polarization. The putative mechanism is that anti-ArtCaM IgE partially blocks the ArtCaM-induced ERK signal, but does not affect Ca2+-dependent cascades. The crosstalk between ERK and Ca2+ signal primes DCs maturation and Th2 polarization. In summary, ArtCaM related to clinical symptoms when combined with anti-ArtCaM IgE, could be a novel allergen to activate DCs and promote Th2 polarization. Such findings provide mechanistic insights into Th2 polarization in allergic sensitization and pave the way for novel preventive and therapeutic strategies for efficient management of such pollen allergic disease.
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Affiliation(s)
- Yue Zhang
- Chinese PLA Medical School, Chinese PLA General Hospital, Beijing, China
- Department of Dermatology, Air Force Medical Center, PLA, Beijing, China
- Department of Dermatology, The First Medical Center of Chinese PLA General Hospital, Beijing, China
| | - Wenzhi Hu
- Department of Dermatology, Air Force Medical Center, PLA, Beijing, China
| | - Dongbo Chen
- Peking University People’s Hospital, Peking University Hepatology Institute, Beijing Key Laboratory of Hepatitis C and Immunotherapy for Liver Disease, Beijing, China
| | - Ming Ding
- Department of Dermatology, Air Force Medical Center, PLA, Beijing, China
| | - Tao Wang
- Department of Dermatology, Air Force Medical Center, PLA, Beijing, China
| | - Yaojun Wang
- Department of Dermatology, Air Force Medical Center, PLA, Beijing, China
| | - Jiaoni Chi
- Department of Dermatology, Air Force Medical Center, PLA, Beijing, China
| | - Zhimin Li
- Department of Dermatology, Air Force Medical Center, PLA, Beijing, China
| | - Qiang Li
- Department of Dermatology, Air Force Medical Center, PLA, Beijing, China
- *Correspondence: Chengxin Li, ; Qiang Li,
| | - Chengxin Li
- Chinese PLA Medical School, Chinese PLA General Hospital, Beijing, China
- Department of Dermatology, The First Medical Center of Chinese PLA General Hospital, Beijing, China
- *Correspondence: Chengxin Li, ; Qiang Li,
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4
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Ransom BR, Goldberg MP, Arai K, Baltan S. White Matter Pathophysiology. Stroke 2022. [DOI: 10.1016/b978-0-323-69424-7.00009-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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5
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Duncan GJ, Simkins TJ, Emery B. Neuron-Oligodendrocyte Interactions in the Structure and Integrity of Axons. Front Cell Dev Biol 2021; 9:653101. [PMID: 33763430 PMCID: PMC7982542 DOI: 10.3389/fcell.2021.653101] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 02/15/2021] [Indexed: 12/12/2022] Open
Abstract
The myelination of axons by oligodendrocytes is a highly complex cell-to-cell interaction. Oligodendrocytes and axons have a reciprocal signaling relationship in which oligodendrocytes receive cues from axons that direct their myelination, and oligodendrocytes subsequently shape axonal structure and conduction. Oligodendrocytes are necessary for the maturation of excitatory domains on the axon including nodes of Ranvier, help buffer potassium, and support neuronal energy metabolism. Disruption of the oligodendrocyte-axon unit in traumatic injuries, Alzheimer's disease and demyelinating diseases such as multiple sclerosis results in axonal dysfunction and can culminate in neurodegeneration. In this review, we discuss the mechanisms by which demyelination and loss of oligodendrocytes compromise axons. We highlight the intra-axonal cascades initiated by demyelination that can result in irreversible axonal damage. Both the restoration of oligodendrocyte myelination or neuroprotective therapies targeting these intra-axonal cascades are likely to have therapeutic potential in disorders in which oligodendrocyte support of axons is disrupted.
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Affiliation(s)
- Greg J Duncan
- Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, Portland, OR, United States
| | - Tyrell J Simkins
- Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, Portland, OR, United States.,Vollum Institute, Oregon Health & Science University, Portland, OR, United States.,Department of Neurology, VA Portland Health Care System, Portland, OR, United States
| | - Ben Emery
- Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, Portland, OR, United States
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6
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Orem BC, Rajaee A, Stirling DP. IP 3R-mediated intra-axonal Ca 2+ release contributes to secondary axonal degeneration following contusive spinal cord injury. Neurobiol Dis 2020; 146:105123. [PMID: 33011333 DOI: 10.1016/j.nbd.2020.105123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 09/15/2020] [Accepted: 09/28/2020] [Indexed: 01/11/2023] Open
Abstract
Secondary axonal loss contributes to the persistent functional disability following trauma. Consequently, preserving axons following spinal cord injury (SCI) is a major therapeutic goal to improve neurological outcome; however, the complex molecular mechanisms that mediate secondary axonal degeneration remain unclear. We previously showed that IP3R-mediated Ca2+ release contributes to axonal dieback and axonal loss following an ex vivo laser-induced SCI. Nevertheless, targeting IP3R in a clinically relevant in vivo model of SCI and determining its contribution to secondary axonal degeneration has yet to be explored. Here we used intravital two-photon excitation microscopy to assess the role of IP3R in secondary axonal degeneration in real-time after a contusive-SCI in vivo. To visualize Ca2+ changes specifically in spinal axons over time, adult 6-8 week-old triple transgenic Avil-Cre:Ai9:Ai95 (sensory neuron-specific expression of tdTomato and the genetic calcium indicator GCaMP6f) mice were subjected to a mild (30 kdyn) T12 contusive-SCI and received delayed treatment with the IP3R blocker 2-APB (100 μM, intrathecal delivery at 3, and 24 h following injury) or vehicle control. To determine the IP3R subtype involved, we knocked-down IP3R3 using capped phosphodiester oligonucleotides. Delayed treatment with 2-APB significantly reduced axonal spheroids, increased axonal survival, and reduced intra-axonal Ca2+ accumulation within dorsal column axons at 24 h following SCI in vivo. Additionally, knockdown of IP3R3 yielded increased axon survival 24 h post-SCI. These results suggest that IP3R-mediated Ca2+ release contributes to secondary axonal degeneration in vivo following SCI.
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Affiliation(s)
- Ben C Orem
- Kentucky Spinal Cord Injury Research Center, University of Louisville, School of Medicine, Louisville, KY 40202, USA; Anatomical Sciences and Neurobiology, University of Louisville, School of Medicine, Louisville, KY 40202, USA
| | - Arezoo Rajaee
- Kentucky Spinal Cord Injury Research Center, University of Louisville, School of Medicine, Louisville, KY 40202, USA; Departments of Neurological Surgery, University of Louisville, School of Medicine, Louisville, KY 40202, USA
| | - David P Stirling
- Kentucky Spinal Cord Injury Research Center, University of Louisville, School of Medicine, Louisville, KY 40202, USA; Departments of Neurological Surgery, University of Louisville, School of Medicine, Louisville, KY 40202, USA; Anatomical Sciences and Neurobiology, University of Louisville, School of Medicine, Louisville, KY 40202, USA; Microbiology and Immunology, University of Louisville, School of Medicine, Louisville, KY 40202, USA.
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7
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Telegin GB, Chernov AS, Konovalov NA, Belogurov AA, Balmasova IP, Gabibov AG. Cytokine Profile As a Marker of Cell Damage and Immune Dysfunction after Spinal Cord Injury. Acta Naturae 2020; 12:92-101. [PMID: 33173599 PMCID: PMC7604889 DOI: 10.32607/actanaturae.11096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 09/08/2020] [Indexed: 12/30/2022] Open
Abstract
This study reviews the findings of recent experiments designed to investigate the cytokine profile after a spinal cord injury. The role played by key cytokines in eliciting the cellular response to trauma was assessed. The results of the specific immunopathogenetic interaction between the nervous and immune systems in the immediate and chronic post-traumatic periods are summarized. It was demonstrated that it is reasonable to use the step-by-step approach to the assessment of the cytokine profile after a spinal cord injury and take into account the combination of the pathogenetic and protective components in implementing the regulatory effects of individual cytokines and their integration into the regenerative processes in the injured spinal cord. This allows one to rationally organize treatment and develop novel drugs.
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Affiliation(s)
- G. B. Telegin
- Branch of Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Pushchino, 142290 Russia
| | - A. S. Chernov
- Branch of Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Pushchino, 142290 Russia
| | - N. A. Konovalov
- N.N. Burdenko National Scientific and Practical Center for Neurosurgery, RF Health Ministry, Moscow, 125047 Russia
| | - A. A. Belogurov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Moscow, 117997 Russia
| | - I. P. Balmasova
- Evdokimov Moscow State University of Medicine and Dentistry of Russia’s Ministry of Health, Moscow, 127473 Russia
| | - A. G. Gabibov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Moscow, 117997 Russia
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8
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Correale J, Marrodan M, Benarroch EE. What is the role of axonal ion channels in multiple sclerosis? Neurology 2020; 95:120-123. [PMID: 32482838 DOI: 10.1212/wnl.0000000000009754] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Affiliation(s)
- Jorge Correale
- From the Department of Neurology (J.C., M.M.), Fleni, Buenos Aires, Argentina; and Department of Neurology (E.E.B.), Mayo Clinic, Rochester, MN.
| | - Mariano Marrodan
- From the Department of Neurology (J.C., M.M.), Fleni, Buenos Aires, Argentina; and Department of Neurology (E.E.B.), Mayo Clinic, Rochester, MN
| | - Eduardo E Benarroch
- From the Department of Neurology (J.C., M.M.), Fleni, Buenos Aires, Argentina; and Department of Neurology (E.E.B.), Mayo Clinic, Rochester, MN
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9
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Wu H, Gao S, Terakawa S. Inhibitory effects of fucoidan on NMDA receptors and l-type Ca 2+ channels regulating the Ca 2+ responses in rat neurons. PHARMACEUTICAL BIOLOGY 2019; 57:1-7. [PMID: 30734636 PMCID: PMC6374951 DOI: 10.1080/13880209.2018.1548626] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 10/19/2018] [Accepted: 11/09/2018] [Indexed: 06/09/2023]
Abstract
CONTEXT Fucoidan, a sulphated polysaccharide extracted from brown algae [Fucus vesiculosus Linn. (Fucaceae)], has multiple biological activities. OBJECTIVE The effects of fucoidan on Ca2+ responses of rat neurons and its probable mechanisms with focus on glutamate receptors were examined. MATERIALS AND METHODS The neurons isolated from the cortex and hippocampi of Wistar rats in postnatal day 1 were employed. The intracellular Ca2+ responses triggered by various stimuli were measured in vitro by Fura-2/AM. Fucoidan at 0.5 mg/mL or 1.5 mg/mL was applied for 3 min to determine its effects on Ca2+ responses. RT-PCR was used to determine the mRNA expression of neuron receptors treated with fucoidan at 0.5 mg/mL for 3 h. RESULTS The Ca2+ responses induced by NMDA were 100% suppressed by fucoidan, and those induced by Bay K8644 90% in the cortical neurons. However, fucoidan has no significant effect on the Ca2+ responses of cortical neurons induced by AMPA or quisqualate. Meanwhile, the Ca2+ responses of hippocampal neurons induced by glutamate, ACPD or adrenaline, showed only a slight decrease following fucoidan treatment. RT-PCR assays of cortical and hippocampal neurons showed that fucoidan treatment significantly decreased the mRNA expression of NMDA-NR1 receptor and the primer pair for l-type Ca2+ channels, PR1/PR2. DISCUSSION AND CONCLUSIONS Our data indicate that fucoidan suppresses the intracellular Ca2+ responses by selectively inhibiting NMDA receptors in cortical neurons and l-type Ca2+ channels in hippocampal neurons. A wide spectrum of fucoidan binding to cell membrane may be useful for designing a general purpose drug in future.
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MESH Headings
- 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester/pharmacology
- Animals
- Calcium/metabolism
- Calcium Channels, L-Type/metabolism
- Cells, Cultured
- Cerebellar Cortex/cytology
- Cerebellar Cortex/drug effects
- Excitatory Amino Acid Agonists/pharmacology
- Glutamic Acid/pharmacology
- Hippocampus/cytology
- Hippocampus/drug effects
- N-Methylaspartate/pharmacology
- Neurons/drug effects
- Neurons/metabolism
- Polysaccharides/pharmacology
- Rats
- Rats, Wistar
- Receptors, AMPA/metabolism
- Receptors, Glutamate/metabolism
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Receptors, N-Methyl-D-Aspartate/biosynthesis
- Receptors, N-Methyl-D-Aspartate/metabolism
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Affiliation(s)
- Hong Wu
- Laboratory of Cell Imaging, Henan University of Chinese Medicine, Zhengzhou, China;
- Photon Medical Research Center, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Shuibo Gao
- Laboratory of Cell Imaging, Henan University of Chinese Medicine, Zhengzhou, China;
| | - Susumu Terakawa
- Photon Medical Research Center, Hamamatsu University School of Medicine, Hamamatsu, Japan
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10
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Katoh H, Yokota K, Fehlings MG. Regeneration of Spinal Cord Connectivity Through Stem Cell Transplantation and Biomaterial Scaffolds. Front Cell Neurosci 2019; 13:248. [PMID: 31244609 PMCID: PMC6563678 DOI: 10.3389/fncel.2019.00248] [Citation(s) in RCA: 99] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 05/17/2019] [Indexed: 12/20/2022] Open
Abstract
Significant progress has been made in the treatment of spinal cord injury (SCI). Advances in post-trauma management and intensive rehabilitation have significantly improved the prognosis of SCI and converted what was once an “ailment not to be treated” into a survivable injury, but the cold hard fact is that we still do not have a validated method to improve the paralysis of SCI. The irreversible functional impairment of the injured spinal cord is caused by the disruption of neuronal transduction across the injury lesion, which is brought about by demyelination, axonal degeneration, and loss of synapses. Furthermore, refractory substrates generated in the injured spinal cord inhibit spontaneous recovery. The discovery of the regenerative capability of central nervous system neurons in the proper environment and the verification of neural stem cells in the spinal cord once incited hope that a cure for SCI was on the horizon. That hope was gradually replaced with mounting frustration when neuroprotective drugs, cell transplantation, and strategies to enhance remyelination, axonal regeneration, and neuronal plasticity demonstrated significant improvement in animal models of SCI but did not translate into a cure in human patients. However, recent advances in SCI research have greatly increased our understanding of the fundamental processes underlying SCI and fostered increasing optimism that these multiple treatment strategies are finally coming together to bring about a new era in which we will be able to propose encouraging therapies that will lead to appreciable improvements in SCI patients. In this review, we outline the pathophysiology of SCI that makes the spinal cord refractory to regeneration and discuss the research that has been done with cell replacement and biomaterial implantation strategies, both by itself and as a combined treatment. We will focus on the capacity of these strategies to facilitate the regeneration of neural connectivity necessary to achieve meaningful functional recovery after SCI.
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Affiliation(s)
- Hiroyuki Katoh
- Division of Genetics and Development, Krembil Research Institute, Toronto, ON, Canada.,Department of Orthopaedic Surgery - Surgical Sciences, School of Medicine, Tokai University, Tokyo, Japan
| | - Kazuya Yokota
- Division of Genetics and Development, Krembil Research Institute, Toronto, ON, Canada.,Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Michael G Fehlings
- Division of Genetics and Development, Krembil Research Institute, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada.,Division of Neurosurgery, University of Toronto, Toronto, ON, Canada.,Spine Program, Toronto Western Hospital, University Health Network, Toronto, ON, Canada
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11
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Witte ME, Schumacher AM, Mahler CF, Bewersdorf JP, Lehmitz J, Scheiter A, Sánchez P, Williams PR, Griesbeck O, Naumann R, Misgeld T, Kerschensteiner M. Calcium Influx through Plasma-Membrane Nanoruptures Drives Axon Degeneration in a Model of Multiple Sclerosis. Neuron 2019; 101:615-624.e5. [PMID: 30686733 PMCID: PMC6389591 DOI: 10.1016/j.neuron.2018.12.023] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 11/09/2018] [Accepted: 12/12/2018] [Indexed: 11/15/2022]
Abstract
Axon loss determines persistent disability in multiple sclerosis patients. Here, we use in vivo calcium imaging in a multiple sclerosis model to show that cytoplasmic calcium levels determine the choice between axon loss and survival. We rule out the endoplasmic reticulum, glutamate excitotoxicity, and the reversal of the sodium-calcium exchanger as sources of intra-axonal calcium accumulation and instead identify nanoscale ruptures of the axonal plasma membrane as the critical path of calcium entry.
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Affiliation(s)
- Maarten E Witte
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians Universität München, Marchioninistraße 15, 81377 Munich, Germany; Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians Universität München, Großhaderner Strasse 9, 82152 Planegg Martinsried, Germany
| | - Adrian-Minh Schumacher
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians Universität München, Marchioninistraße 15, 81377 Munich, Germany; Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians Universität München, Großhaderner Strasse 9, 82152 Planegg Martinsried, Germany
| | - Christoph F Mahler
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians Universität München, Marchioninistraße 15, 81377 Munich, Germany; Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians Universität München, Großhaderner Strasse 9, 82152 Planegg Martinsried, Germany
| | - Jan P Bewersdorf
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians Universität München, Marchioninistraße 15, 81377 Munich, Germany; Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians Universität München, Großhaderner Strasse 9, 82152 Planegg Martinsried, Germany
| | - Jonas Lehmitz
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians Universität München, Marchioninistraße 15, 81377 Munich, Germany; Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians Universität München, Großhaderner Strasse 9, 82152 Planegg Martinsried, Germany; Institute of Neuronal Cell Biology, Technische Universität München, Biedersteiner Straße 29, 80802 Munich, Germany
| | - Alexander Scheiter
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians Universität München, Marchioninistraße 15, 81377 Munich, Germany; Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians Universität München, Großhaderner Strasse 9, 82152 Planegg Martinsried, Germany; Institute of Neuronal Cell Biology, Technische Universität München, Biedersteiner Straße 29, 80802 Munich, Germany
| | - Paula Sánchez
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians Universität München, Marchioninistraße 15, 81377 Munich, Germany; Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians Universität München, Großhaderner Strasse 9, 82152 Planegg Martinsried, Germany
| | - Philip R Williams
- Institute of Neuronal Cell Biology, Technische Universität München, Biedersteiner Straße 29, 80802 Munich, Germany
| | - Oliver Griesbeck
- Max-Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Planegg-Martinsried, Germany
| | - Ronald Naumann
- Max-Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Thomas Misgeld
- Institute of Neuronal Cell Biology, Technische Universität München, Biedersteiner Straße 29, 80802 Munich, Germany; Munich Cluster for Systems Neurology (SyNergy), Feodor-Lynen-Straße 17, 81377 Munich, Germany; German Center for Neurodegenerative Diseases (DZNE), Feodor-Lynen-Straße 17, 81377 Munich, Germany; Center of Integrated Protein Science (CIPSM), Butenandtstraße 5-13, 81377 Munich, Germany.
| | - Martin Kerschensteiner
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians Universität München, Marchioninistraße 15, 81377 Munich, Germany; Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians Universität München, Großhaderner Strasse 9, 82152 Planegg Martinsried, Germany; Munich Cluster for Systems Neurology (SyNergy), Feodor-Lynen-Straße 17, 81377 Munich, Germany.
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12
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Fern R, Matute C. Glutamate receptors and white matter stroke. Neurosci Lett 2018; 694:86-92. [PMID: 30476568 DOI: 10.1016/j.neulet.2018.11.031] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 11/19/2018] [Accepted: 11/21/2018] [Indexed: 12/23/2022]
Abstract
White matter (WM) damage during ischemia occurs at multiple sites including myelin, oligodendrocytes, astrocytes and axons. A major driver of WM demise is excitoxicity as a consequence of excessive glutamate release by vesicular and non-vesicular mechanisms from axons and glial cells. This results in over-activation of ionotropic glutamate receptors (GluRs) profusely expressed by all cell compartments in WM. Thus, blocking excitotoxicity in WM with selective antagonists of those receptors has a potential therapeutic value. The significance of WM GluR expression for WM stroke injury is the focus of this review, and we will examine the role of GluRs in injury to myelin, oligodendrocytes, astrocytes and the axon cylinder.
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Affiliation(s)
- Robert Fern
- Faculty of Medicine and Dentistry, University of Plymouth, Plymouth, United Kingdom
| | - Carlos Matute
- Achucarro Basque Center for Neuroscience, CIBERNED and Department of Neuroscience, University of the Basque Country, Leioa, Spain.
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13
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Wang L, Liu Y, Lu R, Dong G, Chen X, Yun W, Zhou X. The role of S-nitrosylation of kainate-type of ionotropic glutamate receptor 2 in epilepsy induced by kainic acid. J Neurochem 2018; 144:255-270. [PMID: 29193067 DOI: 10.1111/jnc.14266] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 11/21/2017] [Accepted: 11/22/2017] [Indexed: 11/29/2022]
Abstract
Epilepsy is a chronic brain disease affecting millions of individuals. Kainate receptors, especially kainate-type of ionotropic glutamate receptor 2 (GluK2), play an important role in epileptogenesis. Recent data showed that GluK2 could undergo post-translational modifications in terms of S-nitrosylation (SNO), and affect the signaling pathway of cell death in cerebral ischemia-reperfusion. However, it is unclear whether S-nitrosylation of GluK2 (SNO-GluK2) contributes to cell death induced by epilepsy. Here, we report that kainic acid-induced SNO-GluK2 is mediated by GluK2 itself, regulated by neuronal nitric oxide synthase (nNOS) and the level of cytoplasmic calcium in vivo and in vitro hippocampus neurons. The whole-cell patch clamp recordings showed the influence of SNO-GluK2 on ion channel characterization of GluK2-Kainate receptors. Moreover, immunohistochemistry staining results showed that inhibition of SNO-GluK2 by blocking nNOS or GluK2 or by reducing the level of cytoplasmic calcium-protected hippocampal neurons from kainic acid-induced injury. Finally, immunoprecipitation and western blotting data revealed the involvement of assembly of a GluK2-PSD95-nNOS signaling complex in epilepsy. Taken together, our results showed that the SNO-GluK2 plays an important role in neuronal injury of epileptic rats by forming GluK2-PSD95-nNOS signaling module in a cytoplasmic calcium-dependent way, suggesting a potential therapeutic target site for epilepsy.
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Affiliation(s)
- Linxiao Wang
- Laboratory of Neurological Diseases, The affiliated Changzhou No.2 People's Hospital with Nanjing Medical University, Changzhou, Jiangsu Province, China
| | - Yanyan Liu
- Department of Neurology, The affiliated Changzhou No.2 People's Hospital with Nanjing Medical University, Changzhou, Jiangsu Province, China
| | - Rulan Lu
- Laboratory of Neurological Diseases, The affiliated Changzhou No.2 People's Hospital with Nanjing Medical University, Changzhou, Jiangsu Province, China
| | - Guoying Dong
- Laboratory of Neurological Diseases, The affiliated Changzhou No.2 People's Hospital with Nanjing Medical University, Changzhou, Jiangsu Province, China
| | - Xia Chen
- Laboratory of Neurological Diseases, The affiliated Changzhou No.2 People's Hospital with Nanjing Medical University, Changzhou, Jiangsu Province, China
| | - Wenwei Yun
- Department of Neurology, The affiliated Changzhou No.2 People's Hospital with Nanjing Medical University, Changzhou, Jiangsu Province, China
| | - Xianju Zhou
- Laboratory of Neurological Diseases, The affiliated Changzhou No.2 People's Hospital with Nanjing Medical University, Changzhou, Jiangsu Province, China
- Department of Neurology, The affiliated Changzhou No.2 People's Hospital with Nanjing Medical University, Changzhou, Jiangsu Province, China
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14
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Luarte A, Cornejo VH, Bertin F, Gallardo J, Couve A. The axonal endoplasmic reticulum: One organelle-many functions in development, maintenance, and plasticity. Dev Neurobiol 2017; 78:181-208. [PMID: 29134778 DOI: 10.1002/dneu.22560] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 11/02/2017] [Accepted: 11/07/2017] [Indexed: 12/11/2022]
Abstract
The endoplasmic reticulum (ER) is highly conserved in eukaryotes and neurons. Indeed, the localization of the organelle in axons has been known for nearly half a century. However, the relevance of the axonal ER is only beginning to emerge. In this review, we discuss the structure of the ER in axons, examining the role of ER-shaping proteins and highlighting reticulons. We analyze the multiple functions of the ER and their potential contribution to axonal physiology. First, we examine the emerging roles of the axonal ER in lipid synthesis, protein translation, processing, quality control, and secretory trafficking of transmembrane proteins. We also review the impact of the ER on calcium dynamics, focusing on intracellular mechanisms and functions. We describe the interactions between the ER and endosomes, mitochondria, and synaptic vesicles. Finally, we analyze available proteomic data of axonal preparations to reveal the dynamic functionality of the ER in axons during development. We suggest that the dynamic proteome and a validated axonal interactome, together with state-of-the-art methodologies, may provide interesting research avenues in axon physiology that may extend to pathology and regeneration. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 181-208, 2018.
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Affiliation(s)
- Alejandro Luarte
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Víctor Hugo Cornejo
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Francisca Bertin
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Javiera Gallardo
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Andrés Couve
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
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15
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Orem BC, Pelisch N, Williams J, Nally JM, Stirling DP. Intracellular calcium release through IP 3 R or RyR contributes to secondary axonal degeneration. Neurobiol Dis 2017; 106:235-243. [DOI: 10.1016/j.nbd.2017.07.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 06/28/2017] [Accepted: 07/10/2017] [Indexed: 11/27/2022] Open
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16
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Pelisch N, Gomes C, Nally JM, Petruska JC, Stirling DP. Differential expression of ryanodine receptor isoforms after spinal cord injury. Neurosci Lett 2017; 660:51-56. [PMID: 28899787 DOI: 10.1016/j.neulet.2017.09.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 09/07/2017] [Accepted: 09/08/2017] [Indexed: 11/24/2022]
Abstract
Ryanodine receptors (RyRs) are highly conductive intracellular Ca2+ release channels and are widely expressed in many tissues, including the central nervous system. RyRs have been implicated in intracellular Ca2+ overload which can drive secondary damage following traumatic injury to the spinal cord (SCI), but the spatiotemporal expression of the three isoforms of RyRs (RyR1-3) after SCI remains unknown. Here, we analyzed the gene and protein expression of RyR isoforms in the murine lumbar dorsal root ganglion (DRG) and the spinal cord lesion site at 1, 2 and 7 d after a mild contusion SCI. Quantitative RT PCR analysis revealed that RyR3 was significantly increased in lumbar DRGs and at the lesion site at 1 and 2 d post contusion compared to sham (laminectomy only) controls. Additionally, RyR2 expression was increased at 1 d post injury within the lesion site. RyR2 and -3 protein expression was localized to lumbar DRG neurons and their spinal projections within the lesion site acutely after SCI. In contrast, RyR1 expression within the DRG and lesion site remained unaltered following trauma. Our study shows that SCI initiates acute differential expression of RyR isoforms in DRG and spinal cord.
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Affiliation(s)
- Nicolas Pelisch
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA; Department of Neurological Surgery, University of Louisville, Louisville, KY, USA
| | - Cynthia Gomes
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA; Department of Neurological Surgery, University of Louisville, Louisville, KY, USA; Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY, USA
| | - Jacqueline M Nally
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA; Department of Neurological Surgery, University of Louisville, Louisville, KY, USA
| | - Jeffrey C Petruska
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA; Department of Neurological Surgery, University of Louisville, Louisville, KY, USA; Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY, USA
| | - David P Stirling
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA; Department of Neurological Surgery, University of Louisville, Louisville, KY, USA; Department of Microbiology and Immunology, University of Louisville, Louisville, KY, USA; Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY, USA.
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17
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Correale J, Gaitán MI, Ysrraelit MC, Fiol MP. Progressive multiple sclerosis: from pathogenic mechanisms to treatment. Brain 2017; 140:527-546. [PMID: 27794524 DOI: 10.1093/brain/aww258] [Citation(s) in RCA: 201] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 08/18/2016] [Indexed: 12/30/2022] Open
Abstract
During the past decades, better understanding of relapsing-remitting multiple sclerosis disease mechanisms have led to the development of several disease-modifying therapies, reducing relapse rates and severity, through immune system modulation or suppression. In contrast, current therapeutic options for progressive multiple sclerosis remain comparatively disappointing and challenging. One possible explanation is a lack of understanding of pathogenic mechanisms driving progressive multiple sclerosis. Furthermore, diagnosis is usually retrospective, based on history of gradual neurological worsening with or without occasional relapses, minor remissions or plateaus. In addition, imaging methods as well as biomarkers are not well established. Magnetic resonance imaging studies in progressive multiple sclerosis show decreased blood-brain barrier permeability, probably reflecting compartmentalization of inflammation behind a relatively intact blood-brain barrier. Interestingly, a spectrum of inflammatory cell types infiltrates the leptomeninges during subpial cortical demyelination. Indeed, recent magnetic resonance imaging studies show leptomeningeal contrast enhancement in subjects with progressive multiple sclerosis, possibly representing an in vivo marker of inflammation associated to subpial demyelination. Treatments for progressive disease depend on underlying mechanisms causing central nervous system damage. Immunity sheltered behind an intact blood-brain barrier, energy failure, and membrane channel dysfunction may be key processes in progressive disease. Interfering with these mechanisms may provide neuroprotection and prevent disability progression, while potentially restoring activity and conduction along damaged axons by repairing myelin. Although most previous clinical trials in progressive multiple sclerosis have yielded disappointing results, important lessons have been learnt, improving the design of novel ones. This review discusses mechanisms involved in progressive multiple sclerosis, correlations between histopathology and magnetic resonance imaging studies, along with possible new therapeutic approaches.
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18
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Abouelela A, Wieraszko A. The Influence of Glutamate on Axonal Compound Action Potential In Vitro. J Brachial Plex Peripher Nerve Inj 2017; 11:e29-e37. [PMID: 28077958 DOI: 10.1055/s-0036-1593441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 08/14/2016] [Indexed: 10/20/2022] Open
Abstract
Background Our previous experiments demonstrated modulation of the amplitude of the axonal compound action potential (CAP) by electrical stimulation. To verify assumption that glutamate released from axons could be involved in this phenomenon, the modification of the axonal CAP induced by glutamate was investigated. Objectives The major objective of this research is to verify the hypothesis that axonal activity would trigger the release of glutamate, which in turn would interact with specific axonal receptors modifying the amplitude of the action potential. Methods Segments of the sciatic nerve were exposed to exogenous glutamate in vitro, and CAP was recorded before and after glutamate application. In some experiments, the release of radioactive glutamate analog from the sciatic nerve exposed to exogenous glutamate was also evaluated. Results The glutamate-induced increase in CAP was blocked by different glutamate receptor antagonists. The effect of glutamate was not observed in Ca-free medium, and was blocked by antagonists of calcium channels. Exogenous glutamate, applied to the segments of sciatic nerve, induced the release of radioactive glutamate analog, demonstrating glutamate-induced glutamate release. Immunohistochemical examination revealed that axolemma contains components necessary for glutamatergic neurotransmission. Conclusion The proteins of the axonal membrane can under the influence of electrical stimulation or exogenous glutamate change membrane permeability and ionic conductance, leading to a change in the amplitude of CAP. We suggest that increased axonal activity leads to the release of glutamate that results in changes in the amplitude of CAPs.
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Affiliation(s)
- Ahmed Abouelela
- Department of Biology, The College of Staten Island, City University of New York, New York, NY, USA; Program in Neuroscience, The College of Staten Island, City University of New York, New York, NY, USA
| | - Andrzej Wieraszko
- Department of Biology, The College of Staten Island, City University of New York, New York, NY, USA; Program in Neuroscience, The College of Staten Island, City University of New York, New York, NY, USA; Graduate Center, City University of New York, New York, USA
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19
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The pathophysiological role of astrocytic endothelin-1. Prog Neurobiol 2016; 144:88-102. [DOI: 10.1016/j.pneurobio.2016.04.009] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 03/23/2016] [Accepted: 04/25/2016] [Indexed: 12/13/2022]
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20
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Christensen PC, Samadi-Bahrami Z, Pavlov V, Stys PK, Moore GRW. Ionotropic glutamate receptor expression in human white matter. Neurosci Lett 2016; 630:1-8. [PMID: 27443784 DOI: 10.1016/j.neulet.2016.07.030] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 07/14/2016] [Accepted: 07/17/2016] [Indexed: 01/01/2023]
Abstract
Glutamate is the key excitatory neurotransmitter of the central nervous system (CNS). Its role in human grey matter transmission is well understood, but this is less clear in white matter (WM). Ionotropic glutamate receptors (iGluR) are found on both neuronal cell bodies and glia as well as on myelinated axons in rodents, and rodent WM tissue is capable of glutamate release. Thus, rodent WM expresses many of the components of the traditional grey matter neuron-to-neuron synapse, but to date this has not been shown for human WM. We demonstrate the presence of iGluRs in human WM by immunofluorescence employing high-resolution spectral confocal imaging. We found that the obligatory N-methyl-d-aspartic acid (NMDA) receptor subunit GluN1 and the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunit GluA4 co-localized with myelin, oligodendroglial cell bodies and processes. Additionally, GluA4 colocalized with axons, often in distinct clusters. These findings may explain why human WM is vulnerable to excitotoxic events following acute insults such as stroke and traumatic brain injury and in more chronic inflammatory conditions such as multiple sclerosis (MS). Further exploration of human WM glutamate signalling could pave the way for developing future therapies modulating the glutamate-mediated damage in these and other CNS disorders.
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Affiliation(s)
- Pia Crone Christensen
- Hotchkiss Brain Institute, Department of Clinical Neuroscience, University of Calgary, Calgary, Alberta, T2 N 4N1, Canada
| | - Zahra Samadi-Bahrami
- ICORD, (International Collaboration on Repair Discoveries), Department of Pathology and Laboratory Medicine, University of British Columbia, Canada
| | - Vlady Pavlov
- ICORD, (International Collaboration on Repair Discoveries), Department of Pathology and Laboratory Medicine, University of British Columbia, Canada
| | - Peter K Stys
- Hotchkiss Brain Institute, Department of Clinical Neuroscience, University of Calgary, Calgary, Alberta, T2 N 4N1, Canada.
| | - G R Wayne Moore
- ICORD, (International Collaboration on Repair Discoveries), Department of Pathology and Laboratory Medicine, University of British Columbia, Canada
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21
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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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22
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Yandamuri SS, Lane TE. Imaging Axonal Degeneration and Repair in Preclinical Animal Models of Multiple Sclerosis. Front Immunol 2016; 7:189. [PMID: 27242796 PMCID: PMC4871863 DOI: 10.3389/fimmu.2016.00189] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 05/02/2016] [Indexed: 12/25/2022] Open
Abstract
Multiple sclerosis (MS) is a central nervous system (CNS) disease characterized by chronic neuroinflammation, demyelination, and axonal damage. Infiltration of activated lymphocytes and myeloid cells are thought to be primarily responsible for white matter damage and axonopathy. Over time, this neurologic damage manifests clinically as debilitating motor and cognitive symptoms. Existing MS therapies focus on symptom relief and delay of disease progression through reduction of neuroinflammation. However, long-term strategies to remyelinate, protect, or regenerate axons have remained elusive, posing a challenge to treating progressive forms of MS. Preclinical mouse models and techniques, such as immunohistochemistry, flow cytometry, and genomic and proteomic analysis have provided advances in our understanding of discrete time-points of pathology following disease induction. More recently, in vivo and in situ two-photon (2P) microscopy has made it possible to visualize continuous real-time cellular behavior and structural changes occurring within the CNS during neuropathology. Research utilizing 2P imaging to study axonopathy in neuroinflammatory demyelinating disease has focused on five areas: (1) axonal morphologic changes, (2) organelle transport and health, (3) relationship to inflammation, (4) neuronal excitotoxicity, and (5) regenerative therapies. 2P imaging may also be used to identify novel therapeutic targets via identification and clarification of dynamic cellular and molecular mechanisms of axonal regeneration and remyelination. Here, we review tools that have made 2P accessible for imaging neuropathologies and advances in our understanding of axonal degeneration and repair in preclinical models of demyelinating diseases.
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Affiliation(s)
| | - Thomas E. Lane
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA
- Department of Pathology, School of Medicine, University of Utah, Salt Lake City, UT, USA
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23
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Micu I, Plemel JR, Lachance C, Proft J, Jansen AJ, Cummins K, van Minnen J, Stys PK. The molecular physiology of the axo-myelinic synapse. Exp Neurol 2016; 276:41-50. [DOI: 10.1016/j.expneurol.2015.10.006] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 10/20/2015] [Accepted: 10/23/2015] [Indexed: 01/18/2023]
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24
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Luchtman D, Gollan R, Ellwardt E, Birkenstock J, Robohm K, Siffrin V, Zipp F. In vivo and in vitro effects of multiple sclerosis immunomodulatory therapeutics on glutamatergic excitotoxicity. J Neurochem 2016; 136:971-80. [PMID: 26662167 DOI: 10.1111/jnc.13456] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 11/23/2015] [Accepted: 11/24/2015] [Indexed: 11/27/2022]
Abstract
In multiple sclerosis (MS), a candidate downstream mechanism for neuronal injury is glutamate (Glu)-induced excitotoxicity, leading to toxic increases in intraneuronal Ca(2+) . Here, we used in vivo two-photon imaging in the brain of TN-XXL transgenic Ca(2+) reporter mice to test whether promising oral MS therapeutics, namely fingolimod, dimethyl fumarate, and their respective metabolites fingolimod-phosphate and monomethyl fumarate, can protect neurons against acute glutamatergic excitotoxic damage. We also assessed whether these drugs can protect against excitotoxicity in vitro using primary cortical neurons, and whether they can directly inhibit Glu release from pathogenic T-helper 17 lymphocytes. In vivo, direct and acute (1 h) administration of 100 mM Glu to the brainstem resulted in a rapid and significant up-regulation in neuronal Ca(2+) signaling as well as morphological excitotoxic changes that were attenuated by the NMDA-receptor antagonist MK801. Direct CNS administration of MS drugs prior to Glu significantly delayed or reduced, but did not prevent the neuronal Ca(2+) increase or morphological changes. In vitro, prolonged (24 h) treatment of primary neurons with the fumarates significantly protected against neurotoxicity induced by Glu as well as NMDA, similar to MK801. Furthermore, monomethyl fumerate significantly reduced Glu release from pathogenic T-helper 17 lymphocytes. Overall, these data suggest that MS drugs may mediate neuroprotection via excitotoxicity modulating effects. Evidence suggests MS pathogenesis may involve neuronal excitotoxicity, induced by local release of glutamate. However, current MS drugs, including dimethyl fumerate (DMF) and fingolimod (FTY720) are largely anti-inflammatory and not yet fully tested for their neuroprotective potential. Here, we show that the drugs, in particular DMF metabolite monomethyl fumerate (MMF), protect neurons by excitotoxicity modulating effects. Th17, T-helper 17.
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Affiliation(s)
- Dirk Luchtman
- Department of Neurology, Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn²), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - René Gollan
- Department of Neurology, Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn²), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Erik Ellwardt
- Department of Neurology, Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn²), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Jérôme Birkenstock
- Department of Neurology, Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn²), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Kerstin Robohm
- Department of Neurology, Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn²), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Volker Siffrin
- Department of Neurology, Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn²), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Frauke Zipp
- Department of Neurology, Focus Program Translational Neuroscience (FTN), Rhine Main Neuroscience Network (rmn²), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
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25
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Ransom BR, Goldberg MP, Arai K, Baltan S. White Matter Pathophysiology. Stroke 2016. [DOI: 10.1016/b978-0-323-29544-4.00009-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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26
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Abstract
Neuroglia, the "glue" that fills the space between neurons in the central nervous system, takes active part in nerve cell signaling. Neuroglial cells, astroglia, oligodendroglia, and microglia, are together about as numerous as neurons in the brain as a whole, and in the cerebral cortex grey matter, but the proportion varies widely among brain regions. Glial volume, however, is less than one-fifth of the tissue volume in grey matter. When stimulated by neurons or other cells, neuroglial cells release gliotransmitters by exocytosis, similar to neurotransmitter release from nerve endings, or by carrier-mediated transport or channel flux through the plasma membrane. Gliotransmitters include the common neurotransmitters glutamate and GABA, the nonstandard amino acid d-serine, the high-energy phosphate ATP, and l-lactate. The latter molecule is a "buffer" between glycolytic and oxidative metabolism as well as a signaling substance recently shown to act on specific lactate receptors in the brain. Complementing neurotransmission at a synapse, neuroglial transmission often implies diffusion of the transmitter over a longer distance and concurs with the concept of volume transmission. Transmission from glia modulates synaptic neurotransmission based on energetic and other local conditions in a volume of tissue surrounding the individual synapse. Neuroglial transmission appears to contribute significantly to brain functions such as memory, as well as to prevalent neuropathologies.
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Affiliation(s)
- Vidar Gundersen
- SN-Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, and CMBN/SERTA/Healthy Brain Ageing Centre, University of Oslo, Oslo, Norway; Department of Neurology, Oslo University Hospital-Rikshospitalet, Oslo, Norway; Center for Healthy Aging, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; and Brain and Muscle Energy Group, Department of Oral Biology and Division of Anatomy, Department of Molecular Medicine, University of Oslo, Oslo, Norway
| | - Jon Storm-Mathisen
- SN-Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, and CMBN/SERTA/Healthy Brain Ageing Centre, University of Oslo, Oslo, Norway; Department of Neurology, Oslo University Hospital-Rikshospitalet, Oslo, Norway; Center for Healthy Aging, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; and Brain and Muscle Energy Group, Department of Oral Biology and Division of Anatomy, Department of Molecular Medicine, University of Oslo, Oslo, Norway
| | - Linda Hildegard Bergersen
- SN-Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, and CMBN/SERTA/Healthy Brain Ageing Centre, University of Oslo, Oslo, Norway; Department of Neurology, Oslo University Hospital-Rikshospitalet, Oslo, Norway; Center for Healthy Aging, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; and Brain and Muscle Energy Group, Department of Oral Biology and Division of Anatomy, Department of Molecular Medicine, University of Oslo, Oslo, Norway
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27
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Correale J, Farez MF. The Role of Astrocytes in Multiple Sclerosis Progression. Front Neurol 2015; 6:180. [PMID: 26347709 PMCID: PMC4539519 DOI: 10.3389/fneur.2015.00180] [Citation(s) in RCA: 166] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2015] [Accepted: 08/03/2015] [Indexed: 01/03/2023] Open
Abstract
Multiple sclerosis (MS) is an inflammatory disorder causing central nervous system (CNS) demyelination and axonal injury. Although its etiology remains elusive, several lines of evidence support the concept that autoimmunity plays a major role in disease pathogenesis. The course of MS is highly variable; nevertheless, the majority of patients initially present a relapsing–remitting clinical course. After 10–15 years of disease, this pattern becomes progressive in up to 50% of untreated patients, during which time clinical symptoms slowly cause constant deterioration over a period of many years. In about 15% of MS patients, however, disease progression is relentless from disease onset. Published evidence supports the concept that progressive MS reflects a poorly understood mechanism of insidious axonal degeneration and neuronal loss. Recently, the type of microglial cell and of astrocyte activation and proliferation observed has suggested contribution of resident CNS cells may play a critical role in disease progression. Astrocytes could contribute to this process through several mechanisms: (a) as part of the innate immune system, (b) as a source of cytotoxic factors, (c) inhibiting remyelination and axonal regeneration by forming a glial scar, and (d) contributing to axonal mitochondrial dysfunction. Furthermore, regulatory mechanisms mediated by astrocytes can be affected by aging. Notably, astrocytes might also limit the detrimental effects of pro-inflammatory factors, while providing support and protection for oligodendrocytes and neurons. Because of the dichotomy observed in astrocytic effects, the design of therapeutic strategies targeting astrocytes becomes a challenging endeavor. Better knowledge of molecular and functional properties of astrocytes, therefore, should promote understanding of their specific role in MS pathophysiology, and consequently lead to development of novel and more successful therapeutic approaches.
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Affiliation(s)
- Jorge Correale
- Department of Neurology, Institute for Neurological Research Dr. Raúl Carrea, FLENI , Buenos Aires , Argentina
| | - Mauricio F Farez
- Department of Neurology, Institute for Neurological Research Dr. Raúl Carrea, FLENI , Buenos Aires , Argentina
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28
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Tan JW, Wang KY, Liao GJ, Chen FM, Mu MZ. Neuroprotective effect of methylprednisolone combined with placenta-derived mesenchymal stem cell in rabbit model of spinal cord injury. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2015; 8:8976-8982. [PMID: 26464639 PMCID: PMC4583871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 06/22/2015] [Indexed: 06/05/2023]
Abstract
The aim of this study was to assess the ability of the combination treatment of methylprednisolone (MP) and placenta-derived mesenchymal stem cells (PDMSCs) in a rabbit model of spinal cord injury (SCI). Rabbits were randomly divided into four groups: group 1 (control), group 2 (MP), group 3 (PDMSCs) and group 4 (MP + PDMSCs). In all groups, the spinal cord injury model was created by the weight drop method. Levels of malondialdehyde (MDA), myeloperoxidase (MPO), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) were determined by kit. Histopathological examination was also performed. Neurological evaluation was carried out with the Tarlov scoring system. The results showed both MP and PDMSCs had neuroprotective effects, and combining the administration of MP with PDMSCs was shown a significant effect on the recovery of neurological function. Therefore, the combined use of MP and PDMSCs can be used as a potential therapeutic method for SCI.
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Affiliation(s)
- Jiang-Wei Tan
- Department of Spine Surgery, Yantai Affiliated Hospital of Binzhou Medical UniversityYantai 264100, China
| | - Kai-Yan Wang
- Department of Anesthesiology, Yantaishan HospitalYantai 264000, China
| | - Guang-Jun Liao
- Department of Orthopedic Oncology, Yantaishan HospitalYantai 264000, China
| | - Fang-Min Chen
- Department of Spine Surgery, Yantai Affiliated Hospital of Binzhou Medical UniversityYantai 264100, China
| | - Ming-Zhang Mu
- Department of Pediatric Orthopedics, Yantaishan HospitalYantai 264000, China
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Zhang C, Ma J, Fan L, Zou Y, Dang X, Wang K, Song J. Neuroprotective effects of safranal in a rat model of traumatic injury to the spinal cord by anti-apoptotic, anti-inflammatory and edema-attenuating. Tissue Cell 2015; 47:291-300. [DOI: 10.1016/j.tice.2015.03.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 03/13/2015] [Accepted: 03/30/2015] [Indexed: 12/27/2022]
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Bergersen LH. Lactate transport and signaling in the brain: potential therapeutic targets and roles in body-brain interaction. J Cereb Blood Flow Metab 2015; 35:176-85. [PMID: 25425080 PMCID: PMC4426752 DOI: 10.1038/jcbfm.2014.206] [Citation(s) in RCA: 147] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 09/30/2014] [Accepted: 10/24/2014] [Indexed: 12/26/2022]
Abstract
Lactate acts as a 'buffer' between glycolysis and oxidative metabolism. In addition to being exchanged as a fuel by the monocarboxylate transporters (MCTs) between cells and tissues with different glycolytic and oxidative rates, lactate may be a 'volume transmitter' of brain signals. According to some, lactate is a preferred fuel for brain metabolism. Immediately after brain activation, the rate of glycolysis exceeds oxidation, leading to net production of lactate. At physical rest, there is a net efflux of lactate from the brain into the blood stream. But when blood lactate levels rise, such as in physical exercise, there is net influx of lactate from blood to brain, where the lactate is used for energy production and myelin formation. Lactate binds to the lactate receptor GPR81 aka hydroxycarboxylic acid receptor (HCAR1) on brain cells and cerebral blood vessels, and regulates the levels of cAMP. The localization and function of HCAR1 and the three MCTs (MCT1, MCT2, and MCT4) expressed in brain constitute the focus of this review. They are possible targets for new therapeutic drugs and interventions. The author proposes that lactate actions in the brain through MCTs and the lactate receptor underlie part of the favorable effects on the brain resulting from physical exercise.
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Affiliation(s)
- Linda Hildegard Bergersen
- 1] The Brain and Muscle Energy Group, SN-Lab, Department of Anatomy, Institute of Basic Medical Sciences, Healthy Brain Ageing Centre, University of Oslo, Oslo, Norway [2] Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark [3] Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark [4] The Brain and Muscle Energy Group, Department of Oral Biology, University of Oslo, Oslo, Norway
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Rountree CM, Inayat S, Saggere L, Troy JB. Biomimetic stimulation of rat retinal ganglion cells with the neurotransmitter glutamate. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2014:2593-6. [PMID: 25570521 DOI: 10.1109/embc.2014.6944153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Millions of people worldwide face partial or total vision loss due to inherited photoreceptor degenerative diseases, which currently have no cure. Retinal prostheses have been developed to restore vision by electrically stimulating surviving retinal neurons, but have low spatial resolution and nonselectively stimulate retinal ganglion cell (RGC) axons along with somata. We propose a biomimetic solution: using the neurotransmitter glutamate to chemically stimulate RGCs to avoid the disadvantages of electrical stimulation. Our results demonstrate that glutamate stimulation has a spatial resolution comparable to current-generation electrical prostheses, can stimulate RGC somata without stimulating axons, and can produce spatially differential responses in RGC subtypes. These results highlight the benefits of a neurotransmitter-based retinal prosthesis over current-generation electrical prostheses.
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Zhu QJ, Kong FS, Xu H, Wang Y, Du CP, Sun CC, Liu Y, Li T, Hou XY. Tyrosine phosphorylation of GluK2 up-regulates kainate receptor-mediated responses and downstream signaling after brain ischemia. Proc Natl Acad Sci U S A 2014; 111:13990-5. [PMID: 25201974 PMCID: PMC4183319 DOI: 10.1073/pnas.1403493111] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Although kainate receptors play important roles in ischemic stroke, the molecular mechanisms underlying postischemic regulation of kainate receptors remain unclear. In this study we demonstrate that Src family kinases contribute to the potentiation of kainate receptor function. Brain ischemia and reperfusion induce rapid and sustained phosphorylation of the kainate receptor subunit GluK2 by Src in the rat hippocampus, implicating a critical role for Src-mediated GluK2 phosphorylation in ischemic brain injury. The NMDA and kainate receptors are involved in the tyrosine phosphorylation of GluK2. GluK2 binds to Src, and the tyrosine residue at position 590 (Y590) on GluK2 is a major site of phosphorylation by Src kinases. GluK2 phosphorylation at Y590 is responsible for increases in whole-cell currents and calcium influx in response to transient kainate stimulation. In addition, GluK2 phosphorylation at Y590 facilitates the endocytosis of GluK2 subunits, and the activation of JNK3 and its substrate c-Jun after long-term kainate treatment. Thus, Src phosphorylation of GluK2 plays an important role in the opening of kainate receptor channels and downstream proapoptosis signaling after brain ischemia. The present study reveals an additional mechanism for the regulation of GluK2-containing kainate receptors by Src family kinases, which may be of pathological significance in ischemic stroke.
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Affiliation(s)
- Qiu-Ju Zhu
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical College, Jiangsu 221004, China
| | - Fan-Shu Kong
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical College, Jiangsu 221004, China
| | - Hao Xu
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical College, Jiangsu 221004, China
| | - Yi Wang
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical College, Jiangsu 221004, China
| | - Cai-Ping Du
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical College, Jiangsu 221004, China
| | - Chang-Cheng Sun
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical College, Jiangsu 221004, China
| | - Yong Liu
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical College, Jiangsu 221004, China
| | - Ting Li
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical College, Jiangsu 221004, China
| | - Xiao-Yu Hou
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical College, Jiangsu 221004, China
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Azevedo CJ, Kornak J, Chu P, Sampat M, Okuda DT, Cree BA, Nelson SJ, Hauser SL, Pelletier D. In vivo evidence of glutamate toxicity in multiple sclerosis. Ann Neurol 2014; 76:269-78. [PMID: 25043416 DOI: 10.1002/ana.24202] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 06/10/2014] [Accepted: 06/15/2014] [Indexed: 11/12/2022]
Abstract
OBJECTIVE There is increasing evidence that altered glutamate (Glu) homeostasis is involved in the pathophysiology of multiple sclerosis (MS). The aim of this study was to evaluate the in vivo effects of excess brain Glu on neuroaxonal integrity measured by N-acetylaspartate (NAA), brain volume, and clinical outcomes in a large, prospectively followed cohort of MS subjects. METHODS We used multivoxel spectroscopy at 3T to longitudinally estimate Glu and NAA concentrations from large areas of normal-appearing white and gray matter (NAWM and GM) in MS patients (n = 343) with a mean follow-up time of 5 years. Using linear mixed-effects models, Glu was examined as a predictor of NAA decline, annualized percentage brain volume change, and evolution of clinical outcomes (Multiple Sclerosis Functional Composite [MSFC], Paced Auditory Serial Addition Test-3 [PASAT], and Expanded Disability Status Scale). Glu/NAA ratio was tested as a predictor of brain volume loss and clinical outcomes. RESULTS Baseline Glu[NAWM] was predictive of accelerated longitudinal decline in NAA[GM] (-0.06mM change in NAA[GM] /yr for each unit increase in Glu; p = 0.004). The sustained elevation of Glu[NAWM] was predictive of a loss of 0.28mM/yr in NAA[NAWM] (p < 0.001) and 0.15mM/yr in NAA[GM] (p = 0.056). Each 10% increase in Glu/NAA[NAWM] was associated with a loss of 0.33% brain volume/yr (p = 0.001), 0.009 standard deviations/yr in MSFC z-score (p < 0.001), and 0.17 points/yr on the PASAT (p < 0.001). INTERPRETATION These results indicate that higher Glu concentrations increase the rate of NAA decline, and higher Glu/NAA[NAWM] ratio increases the rate of decline of brain volume, MSFC, and PASAT. This provides evidence of a relationship between brain Glu and markers of disease progression in MS.
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Plemel JR, Keough MB, Duncan GJ, Sparling JS, Yong VW, Stys PK, Tetzlaff W. Remyelination after spinal cord injury: Is it a target for repair? Prog Neurobiol 2014; 117:54-72. [DOI: 10.1016/j.pneurobio.2014.02.006] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Revised: 02/15/2014] [Accepted: 02/20/2014] [Indexed: 12/12/2022]
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Abstract
PURPOSE OF REVIEW The predominant clinical disease course of multiple sclerosis starts with reversible episodes of neurological disability, which transforms into progressive neurological decline. This review provides insight into the pathological differences during relapsing and progressive phases of multiple sclerosis. RECENT FINDINGS The clinical course of multiple sclerosis is variable, and the disease can be classified into relapsing and progressive phases. Pathological studies have been successful in distinguishing between these two forms of the disease and correlate with the clinical findings in terms of cellular responses, the inflammatory environment, and the location of lesions. SUMMARY Available therapies for multiple sclerosis patients, while effective during the relapsing phase, have little benefit for progressive multiple sclerosis patients. Development of therapies to benefit progressive multiple sclerosis patients will require a better understanding of the pathogenesis of progressive multiple sclerosis. This review discusses and compares the pathological findings in relapsing and progressive multiple sclerosis patients.
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Affiliation(s)
- Ranjan Dutta
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
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36
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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: 80] [Impact Index Per Article: 8.0] [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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37
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Levin MC, Douglas JN, Meyers L, Lee S, Shin Y, Gardner LA. Neurodegeneration in multiple sclerosis involves multiple pathogenic mechanisms. Degener Neurol Neuromuscul Dis 2014; 4:49-63. [PMID: 32669900 PMCID: PMC7337253 DOI: 10.2147/dnnd.s54391] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 03/06/2014] [Indexed: 12/18/2022] Open
Abstract
Multiple sclerosis (MS) is a complex autoimmune disease that impairs the central nervous system (CNS). The neurological disability and clinical course of the disease is highly variable and unpredictable from one patient to another. The cause of MS is still unknown, but it is thought to occur in genetically susceptible individuals who develop disease due to a nongenetic trigger, such as altered metabolism, a virus, or other environmental factors. MS patients develop progressive, irreversible, neurological disability associated with neuronal and axonal damage, collectively known as neurodegeneration. Neurodegeneration was traditionally considered as a secondary phenomenon to inflammation and demyelination. However, recent data indicate that neurodegeneration develops along with inflammation and demyelination. Thus, MS is increasingly recognized as a neurodegenerative disease triggered by an inflammatory attack of the CNS. While both inflammation and demyelination are well described and understood cellular processes, neurodegeneration might be defined by a diverse pool of any of the following: neuronal cell death, apoptosis, necrosis, and virtual hypoxia. In this review, we present multiple theories and supporting evidence that identify common biological processes that contribute to neurodegeneration in MS.
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Affiliation(s)
- Michael C Levin
- Veterans Administration Medical Center.,Department of Neuroscience, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Joshua N Douglas
- Veterans Administration Medical Center.,Department of Neuroscience, University of Tennessee Health Science Center, Memphis, TN, USA
| | | | - Sangmin Lee
- Veterans Administration Medical Center.,Department of Neurology
| | - Yoojin Shin
- Veterans Administration Medical Center.,Department of Neurology
| | - Lidia A Gardner
- Veterans Administration Medical Center.,Department of Neurology
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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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Diabetic peripheral neuropathy: Current perspective and future directions. Pharmacol Res 2014; 80:21-35. [DOI: 10.1016/j.phrs.2013.12.005] [Citation(s) in RCA: 201] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 11/26/2013] [Accepted: 12/16/2013] [Indexed: 01/17/2023]
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40
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Hauser SL, Chan JR, Oksenberg JR. Multiple sclerosis: Prospects and promise. Ann Neurol 2013; 74:317-27. [PMID: 23955638 DOI: 10.1002/ana.24009] [Citation(s) in RCA: 152] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 08/05/2013] [Indexed: 12/15/2022]
Abstract
We have entered a golden era in multiple sclerosis (MS) research. Two decades ago, our understanding of the disease was largely descriptive and there were no approved therapies to modify the natural history of MS. Today, delineation of immune pathways relevant to MS have been clarified; a comprehensive map of genes that influence risk compiled; clues to environmental triggers identified; noninvasive in vivo monitoring of the MS disease process has been revolutionized by high-field MRI; and many effective therapies for the early, relapsing, component of MS now exist. However, major challenges remain. We still have no useful treatment for progressive MS (the holy grail of MS research), no means to repair injured axons or protect neurons, and extremely limited evidence to guide treatment decisions. Recent advances have set in place a foundation for development of increasingly selective immunotherapy for patients; application of genetic and genomic discoveries to improve therapeutic options; development of remyelination or neuroprotection therapies for progressive MS; and integrating clinical, imaging and genomic data for personalized medicine. MS has now advanced from the backwaters of autoimmune disease research to the front-line, and definitive answers, including cures, are now realistic goals for the next decade. Many of the breakthrough discoveries in MS have also resulted from meaningful interactions across disciplines, and especially from translational and basic scientists working closely with clinicians, highlighting that the clinical value of discoveries are most often revealed when ideas developed in the laboratory are tested at the bedside.
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Affiliation(s)
- Stephen L Hauser
- Department of Neurology, University of California, San Francisco, San Francisco, CA
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41
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Song M, Yu SP. Ionic regulation of cell volume changes and cell death after ischemic stroke. Transl Stroke Res 2013; 5:17-27. [PMID: 24323733 DOI: 10.1007/s12975-013-0314-x] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 10/16/2013] [Accepted: 11/19/2013] [Indexed: 12/20/2022]
Abstract
Stroke is a leading cause of human death and disability in the USA and around the world. Shortly after the cerebral ischemia, cell swelling is the earliest morphological change in injured neuronal, glial, and endothelial cells. Cytotoxic swelling directly results from increased Na(+) (with H2O) and Ca(2+) influx into cells via ionic mechanisms evoked by membrane depolarization and a number of harmful factors such as glutamate accumulation and the production of oxygen reactive species. During the sub-acute and chronic phases after ischemia, injured cells may show a phenotype of cell shrinkage due to complex processes involving membrane receptors/channels and programmed cell death signals. This review will introduce some progress in the understanding of the regulation of pathological cell volume changes and the involved receptors and channels, including NMDA and AMPA receptors, acid-sensing ion channels, hemichannels, transient receptor potential channels, and KCNQ channels. Moreover, accumulating evidence supports a key role of energy deficiency and dysfunction of Na(+)/K(+)-ATPase in ischemia-induced cell volume changes and cell death. Specifically, the Na(+) pump failure is a prerequisite for disruption of ionic homeostasis including a pro-apoptotic disruption of the K(+) homeostasis. Finally, we will introduce the concept of hybrid cell death as a result of the Na(+) pump failure in cultured cells and the ischemic brain. The goal of this review is to outline recent understanding of the ionic mechanism of ischemic cytotoxicity and suggest innovative ideas for future translational research.
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Affiliation(s)
- Mingke Song
- Department of Anesthesiology, Emory University School of Medicine, 101 Woodruff Circle, WMB Building Suite 620, Atlanta, GA, 30322, USA
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Ma M. Role of calpains in the injury-induced dysfunction and degeneration of the mammalian axon. Neurobiol Dis 2013; 60:61-79. [PMID: 23969238 PMCID: PMC3882011 DOI: 10.1016/j.nbd.2013.08.010] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 07/17/2013] [Accepted: 08/08/2013] [Indexed: 12/21/2022] Open
Abstract
Axonal injury and degeneration, whether primary or secondary, contribute to the morbidity and mortality seen in many acquired and inherited central nervous system (CNS) and peripheral nervous system (PNS) disorders, such as traumatic brain injury, spinal cord injury, cerebral ischemia, neurodegenerative diseases, and peripheral neuropathies. The calpain family of proteases has been mechanistically linked to the dysfunction and degeneration of axons. While the direct mechanisms by which transection, mechanical strain, ischemia, or complement activation trigger intra-axonal calpain activity are likely different, the downstream effects of unregulated calpain activity may be similar in seemingly disparate diseases. In this review, a brief examination of axonal structure is followed by a focused overview of the calpain family. Finally, the mechanisms by which calpains may disrupt the axonal cytoskeleton, transport, and specialized domains (axon initial segment, nodes, and terminals) are discussed.
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Affiliation(s)
- Marek Ma
- Department of Emergency Medicine, University of Pennsylvania, Philadelphia, PA, USA; Center for Resuscitation Science, University of Pennsylvania, Philadelphia, PA, USA.
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43
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Rinholm JE, Bergersen LH. White matter lactate--does it matter? Neuroscience 2013; 276:109-16. [PMID: 24125892 DOI: 10.1016/j.neuroscience.2013.10.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 09/12/2013] [Accepted: 10/02/2013] [Indexed: 10/26/2022]
Abstract
About half of the human brain is white matter, characterized by axons covered in myelin, which facilitates the high speed of nerve signals from one brain area to another. At the time of myelination, the oligodendrocytes that synthesize myelin require a large amount of energy for this task. Conditions that deprive the tissue of energy can kill the oligodendrocytes. During brain development, the oligodendrocytes may use lactate as an alternative source of energy and material for myelin formation. Mature oligodendrocytes, however, can release lactate through the myelin sheath as nutrient for axons. In addition, lactate carries signals as a volume transmitter. Myelin thus seems to serve as a provider of substrates and signals for axons, and not as a mere insulator. We review the fluxes of lactate in white matter and their significance in brain function.
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Affiliation(s)
- J E Rinholm
- The Brain and Muscle Energy Group, Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, PB1105 Blindern, N-0317 Oslo, Norway; Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - L H Bergersen
- The Brain and Muscle Energy Group, Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, PB1105 Blindern, N-0317 Oslo, Norway; Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark; Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Oral Biology, University of Oslo, Norway.
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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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Ectopic vesicular glutamate release at the optic nerve head and axon loss in mouse experimental glaucoma. J Neurosci 2013; 32:15859-76. [PMID: 23136425 DOI: 10.1523/jneurosci.0038-12.2012] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Although clinical and experimental observations indicate that the optic nerve head (ONH) is a major site of axon degeneration in glaucoma, the mechanisms by which local retinal ganglion cell (RGC) axons are injured and damage spreads among axons remain poorly defined. Using a laser-induced ocular hypertension (LIOH) mouse model of glaucoma, we found that within 48 h of intraocular pressure elevation, RGC axon segments within the ONH exhibited ectopic accumulation and colocalization of multiple components of the glutamatergic presynaptic machinery including the vesicular glutamate transporter VGLUT2, several synaptic vesicle marker proteins, glutamate, the soluble N-ethylmaleimide-sensitive factor attachment protein receptor complex and active zone cytomatrix components, as well as ultrastructurally identified, synaptophysin-containing vesicles. Ectopic vesicle exocytosis and glutamate release were detected in acute preparations of the LIOH ONH. Immunolocalization and analysis using the ionotropic receptor channel-permeant cation agmatine indicated that ONH axon segments and glia expressed glutamate receptors, and these receptors were more active after LIOH compared with controls. Pharmacological antagonism of glutamate receptors and neuronal activity resulted in increased RGC axon sparing in vivo. Furthermore, in vivo RGC-specific genetic disruption of the vesicular glutamate transporter VGLUT2 or the obligatory NMDA receptor subunit NR1 promoted axon survival in experimental glaucoma. As the inhibition of ectopic glutamate vesicular release or glutamate receptivity can independently modify the severity of RGC axon loss, synaptic release mechanisms may provide useful therapeutic entry points into glaucomatous axon degeneration.
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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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47
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de Lago E, Gómez-Ruiz M, Moreno-Martet M, Fernández-Ruiz J. Cannabinoids, multiple sclerosis and neuroprotection. Expert Rev Clin Pharmacol 2012; 2:645-60. [PMID: 22112258 DOI: 10.1586/ecp.09.42] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The cannabinoid signaling system participates in the control of cell homeostasis in the CNS, which explains why, in different neurodegenerative diseases including multiple sclerosis (MS), alterations in this system have been found to serve both as a pathogenic factor (malfunctioning of this system has been found at early phases of these diseases) and as a therapeutic target (the management of this system has beneficial effects). MS is an autoimmune disease that affects the CNS and it is characterized by inflammation, demyelination, remyelination, gliosis and axonal damage. Although it has been considered mainly as an inflammatory disorder, recent studies have recognized the importance of axonal loss both in the progression of the disorder and in the appearance of neurological disability, even in early stages of the disease. In recent years, several laboratories have addressed the therapeutic potential of cannabinoids in MS, given the experience reported by some MS patients who self-medicated with marijuana. Most of these studies focused on the alleviation of symptoms (spasticity, tremor, anxiety and pain) or on the inflammatory component of the disease. However, recent data also revealed the important neuroprotective action that could be exerted by cannabinoids in this disorder. The present review will be precisely centered on this neuroprotective potential, which is based mainly on antioxidant, anti-inflammatory and anti-excitotoxic properties, exerted through the activation of CB1 or CB2 receptors or other unknown mechanisms.
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Affiliation(s)
- Eva de Lago
- Departamento de Bioquímica y Biología Molecular and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Facultad de Medicina, Universidad Complutense, 28040 Madrid, Spain.
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Lassmann H, van Horssen J, Mahad D. Progressive multiple sclerosis: pathology and pathogenesis. Nat Rev Neurol 2012; 8:647-56. [PMID: 23007702 DOI: 10.1038/nrneurol.2012.168] [Citation(s) in RCA: 651] [Impact Index Per Article: 54.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Major progress has been made during the past three decades in understanding the inflammatory process and pathogenetic mechanisms in multiple sclerosis (MS). Consequently, effective anti-inflammatory and immunomodulatory treatments are now available for patients in the relapsing-remitting stage of the disease. This Review summarizes studies on the pathology of progressive MS and discusses new data on the mechanisms underlying its pathogenesis. In progressive MS, as in relapsing-remitting MS, active tissue injury is associated with inflammation, but the inflammatory response in the progressive phase occurs at least partly behind the blood-brain barrier, which makes it more difficult to treat. The other mechanisms that drive disease in patients with primary or secondary progressive MS are currently unresolved, although oxidative stress resulting in mitochondrial injury might participate in the induction of demyelination and neurodegeneration in both the relapsing-remitting and progressive stages of MS. Oxidative stress seems to be mainly driven by inflammation and oxidative burst in microglia; however, its effects might be amplified in patients with progressive MS by age-dependent iron accumulation in the brain and by mitochondrial gene deletions, triggered by the chronic inflammatory process.
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Affiliation(s)
- Hans Lassmann
- Centre for Brain Research, Medical University of Vienna, Wien, Austria.
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Molecular pathology, classification, and diagnosis of sporadic human prion disease variants. Folia Neuropathol 2012; 4:AN20110031. [PMID: 22356284 PMCID: PMC3284768 DOI: 10.1042/an20110031] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Glutamate excitotoxicity is a major pathogenic process implicated in many neurodegenerative conditions, including AD (Alzheimer's disease) and following traumatic brain injury. Occurring predominantly from over-stimulation of ionotropic glutamate receptors located along dendrites, excitotoxic axonal degeneration may also occur in white matter tracts. Recent identification of axonal glutamate receptor subunits within axonal nanocomplexes raises the possibility of direct excitotoxic effects on axons. Individual neuronal responses to excitotoxicity are highly dependent on the complement of glutamate receptors expressed by the cell, and the localization of the functional receptors. To enable isolation of distal axons and targeted excitotoxicity, murine cortical neuron cultures were prepared in compartmented microfluidic devices, such that distal axons were isolated from neuronal cell bodies. Within the compartmented culture system, cortical neurons developed to relative maturity at 11 DIV (days in vitro) as demonstrated by the formation of dendritic spines and clustering of the presynaptic protein synaptophysin. The isolated distal axons retained growth cone structures in the absence of synaptic targets, and expressed glutamate receptor subunits. Glutamate treatment (100 μM) to the cell body chamber resulted in widespread degeneration within this chamber and degeneration of distal axons in the other chamber. Glutamate application to the distal axon chamber triggered a lesser degree of axonal degeneration without degenerative changes in the untreated somal chamber. These data indicate that in addition to current mechanisms of indirect axonal excitotoxicity, the distal axon may be a primary target for excitotoxicity in neurodegenerative conditions.
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Xing Y, Samuvel DJ, Stevens SM, Dubno JR, Schulte BA, Lang H. Age-related changes of myelin basic protein in mouse and human auditory nerve. PLoS One 2012; 7:e34500. [PMID: 22496821 PMCID: PMC3320625 DOI: 10.1371/journal.pone.0034500] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 03/06/2012] [Indexed: 11/19/2022] Open
Abstract
Age-related hearing loss (presbyacusis) is the most common type of hearing impairment. One of the most consistent pathological changes seen in presbyacusis is the loss of spiral ganglion neurons (SGNs). Defining the cellular and molecular basis of SGN degeneration in the human inner ear is critical to gaining a better understanding of the pathophysiology of presbyacusis. However, information on age-related cellular and molecular alterations in the human spiral ganglion remains scant, owing to the very limited availably of human specimens suitable for high resolution morphological and molecular analysis. This study aimed at defining age-related alterations in the auditory nerve in human temporal bones and determining if immunostaining for myelin basic protein (MBP) can be used as an alternative approach to electron microscopy for evaluating myelin degeneration. For comparative purposes, we evaluated ultrastructural alternations and changes in MBP immunostaining in aging CBA/CaJ mice. We then examined 13 temporal bones from 10 human donors, including 4 adults aged 38-46 years (middle-aged group) and 6 adults aged 63-91 years (older group). Similar to the mouse, intense immunostaining of MBP was present throughout the auditory nerve of the middle-aged human donors. Significant declines in MBP immunoreactivity and losses of MBP(+) auditory nerve fibers were observed in the spiral ganglia of both the older human and aged mouse ears. This study demonstrates that immunostaining for MBP in combination with confocal microscopy provides a sensitive, reliable, and efficient method for assessing alterations of myelin sheaths in the auditory nerve. The results also suggest that myelin degeneration may play a critical role in the SGN loss and the subsequent decline of the auditory nerve function in presbyacusis.
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Affiliation(s)
- Yazhi Xing
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Devadoss J. Samuvel
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Shawn M. Stevens
- Department of Otolaryngology – Head & Neck Surgery, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Judy R. Dubno
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
- Department of Otolaryngology – Head & Neck Surgery, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Bradley A. Schulte
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
- Department of Otolaryngology – Head & Neck Surgery, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Hainan Lang
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
- * E-mail:
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