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Shin-Yi Lin C, Howells J, Rutkove S, Nandedkar S, Neuwirth C, Noto YI, Shahrizaila N, Whittaker RG, Bostock H, Burke D, Tankisi H. Neurophysiological and imaging biomarkers of lower motor neuron dysfunction in motor neuron diseases/amyotrophic lateral sclerosis: IFCN handbook chapter. Clin Neurophysiol 2024; 162:91-120. [PMID: 38603949 DOI: 10.1016/j.clinph.2024.03.015] [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: 10/03/2023] [Revised: 02/07/2024] [Accepted: 03/12/2024] [Indexed: 04/13/2024]
Abstract
This chapter discusses comprehensive neurophysiological biomarkers utilised in motor neuron disease (MND) and, in particular, its commonest form, amyotrophic lateral sclerosis (ALS). These encompass the conventional techniques including nerve conduction studies (NCS), needle and high-density surface electromyography (EMG) and H-reflex studies as well as novel techniques. In the last two decades, new methods of assessing the loss of motor units in a muscle have been developed, that are more convenient than earlier methods of motor unit number estimation (MUNE),and may use either electrical stimulation (e.g. MScanFit MUNE) or voluntary activation (MUNIX). Electrical impedance myography (EIM) is another novel approach for the evaluation that relies upon the application and measurement of high-frequency, low-intensity electrical current. Nerve excitability techniques (NET) also provide insights into the function of an axon and reflect the changes in resting membrane potential, ion channel dysfunction and the structural integrity of the axon and myelin sheath. Furthermore, imaging ultrasound techniques as well as magnetic resonance imaging are capable of detecting the constituents of morphological changes in the nerve and muscle. The chapter provides a critical description of the ability of each technique to provide neurophysiological insight into the complex pathophysiology of MND/ALS. However, it is important to recognise the strengths and limitations of each approach in order to clarify utility. These neurophysiological biomarkers have demonstrated reliability, specificity and provide additional information to validate and assess lower motor neuron dysfunction. Their use has expanded the knowledge about MND/ALS and enhanced our understanding of the relationship between motor units, axons, reflexes and other neural circuits in relation to clinical features of patients with MND/ALS at different stages of the disease. Taken together, the ultimate goal is to aid early diagnosis, distinguish potential disease mimics, monitor and stage disease progression, quantify response to treatment and develop potential therapeutic interventions.
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Affiliation(s)
- Cindy Shin-Yi Lin
- Faculty of Medicine and Health, Central Clinical School, Brain and Mind Centre, University of Sydney, Sydney 2006, Australia.
| | - James Howells
- Central Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - Seward Rutkove
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Sanjeev Nandedkar
- Natus Medical Inc, Middleton, Wisconsin, USA and Medical College of Wisconsin, Milwaukee, WI, USA
| | - Christoph Neuwirth
- Neuromuscular Diseases Unit/ALS Clinic, Kantonsspital, St. Gallen, Switzerland
| | - Yu-Ichi Noto
- Department of Neurology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Nortina Shahrizaila
- Division of Neurology, Department of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia
| | - Roger G Whittaker
- Newcastle University Translational and Clinical Research Institute (NUTCRI), Newcastle University., Newcastle Upon Tyne, United Kingdom
| | - Hugh Bostock
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, Queen Square, WC1N 3BG, London, United Kingdom
| | - David Burke
- Central Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - Hatice Tankisi
- Department of Clinical Neurophysiology, Aarhus University Hospital and Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
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Lugg A, Schindle M, Sivak A, Tankisi H, Jones KE. Nerve excitability measured with the TROND protocol in amyotrophic lateral sclerosis: a systematic review and meta-analysis. J Neurophysiol 2023; 130:1480-1491. [PMID: 37910562 DOI: 10.1152/jn.00174.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 10/30/2023] [Accepted: 10/31/2023] [Indexed: 11/03/2023] Open
Abstract
This meta-analysis assessed the 30+ nerve excitability indices generated by the TROND protocol to identify potential biomarkers for amyotrophic lateral sclerosis (ALS). A comprehensive search was conducted in multiple databases to identify human studies that tested median motor axons. Forest plot analyses were performed using a random-effects model to determine the pooled effect (Z-score), heterogeneity (I2), and Cohen's d for potential biomarker identification. Out of 2,866 studies, 23 studies met the inclusion criteria, incorporating data from 719 controls and 942 patients with ALS. Seven indices emerged as potential biomarkers: depolarizing threshold electrotonus (TEd) 90-100 ms, strength-duration time constant (SDTC), superexcitability, TEd 40-60 ms, resting I/V slope, 50% depolarizing I/V, and subexcitability (ranked by the magnitude of the difference between patients and controls from largest to smallest). In a sensitivity analysis focusing on patients with larger compound muscle action potentials (CMAPs), only four indices were potential biomarkers: TEd 10-20 ms, TEd 90-100 ms, superexcitability, and SDTC. Among the extensive range of 30+ excitability indices generated by the TROND protocol, we have identified seven indices that effectively differentiate patients with ALS from healthy controls. Furthermore, a smaller subset of four indices shows promise as potential biomarkers when the CMAP remains relatively large. However, most studies were considered to be at moderate risk of bias due to case-control designs and absence of sensitivity and specificity calculations, underscoring the need for more prospective diagnostic test-accuracy studies with appropriate disease controls.NEW & NOTEWORTHY This meta-analysis uncovers seven potential axonal excitability biomarkers for lower motor neuron pathology in ALS, shedding light on ion channel dysfunction. The identified dysfunction aligns with the primary pathology-protein homeostasis disruption. These biomarkers could fill a gap to detect presymptomatic spread of the disease in the spinal cord and monitor treatments targeting protein homeostasis and limiting spread, toward enhancing patient care.
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Affiliation(s)
- Anna Lugg
- Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Mason Schindle
- Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Allison Sivak
- University of Alberta Library, Edmonton, Alberta, Canada
| | - Hatice Tankisi
- Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark
| | - Kelvin E Jones
- Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada
- Neuroscience and Mental Health Institute, Edmonton, Alberta, Canada
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Menon P, Pavey N, Aberra AS, van den Bos MAJ, Wang R, Kiernan MC, Peterchev AV, Vucic S. Dependence of cortical neuronal strength-duration properties on TMS pulse shape. Clin Neurophysiol 2023; 150:106-118. [PMID: 37060842 PMCID: PMC10280814 DOI: 10.1016/j.clinph.2023.03.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 02/13/2023] [Accepted: 03/08/2023] [Indexed: 04/17/2023]
Abstract
OBJECTIVE The aim of present study was to explore the effects of different combinations of transcranial magnetic stimulation (TMS) pulse width and pulse shape on cortical strength-duration time constant (SDTC) and rheobase measurements. METHODS Resting motor thresholds (RMT) at pulse widths (PW) of 30, 45, 60, 90 and 120 µs and M-ratios of 0.2, 0.1 and 0.025 were determined using figure-of-eight coil with initial posterior-to-anterior induced current. The M-ratio indicates the relative phases of the induced current with lower values signifying a more unidirectional stimulus. Strength-duration time constant (SDTC) and rheobase were estimated for each M-ratio and various PW combinations. Simulations of biophysically realistic cortical neuron models assessed underlying neuronal populations and physiological mechanisms mediating pulse shape effects on strength-duration properties. RESULTS The M-ratio exerted significant effect on SDTC (F(2,44) = 4.386, P = 0.021), which was longer for M-ratio of 0.2 (243.4 ± 61.2 µs) compared to 0.025 (186.7 ± 52.5 µs, P = 0.034). Rheobase was significantly smaller when assessed with M-ratio 0.2 compared to 0.025 (P = 0.026). SDTC and rheobase values were most consistent with pulse width sets of 30/45/60/90/120 µs, 30/60/90/120 µs, and 30/60/120 µs. Simulation studies indicated that isolated pyramidal neurons in layers 2/3, 5, and large basket-cells in layer 4 exhibited SDTCs comparable to experimental results. Further, simulation studies indicated that reducing transient Na+ channel conductance increased SDTC with larger increases for higher M-ratios. CONCLUSIONS Cortical strength-duration curve properties vary with pulse shape, and the modulating effect of the hyperpolarising pulse phase on cortical axonal transient Na+ conductances could account for these changes, although a shift in the recruited neuronal populations may contribute as well. SIGNIFICANCE The dependence of the cortical strength-duration curve properties on the TMS pulse shape and pulse width selection underscores the need for consistent measurement methods across studies and the potential to extract information about pathophysiological processes.
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Affiliation(s)
- Parvathi Menon
- Brain and Nerve Research Centre, Concord Clinical School, University of Sydney, Concord Hospital, Sydney, Australia
| | - Nathan Pavey
- Brain and Nerve Research Centre, Concord Clinical School, University of Sydney, Concord Hospital, Sydney, Australia
| | - Aman S Aberra
- Department of Biological Sciences, Dartmouth College, Hanover, NH, USA
| | - Mehdi A J van den Bos
- Brain and Nerve Research Centre, Concord Clinical School, University of Sydney, Concord Hospital, Sydney, Australia
| | - Ruochen Wang
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | | | - Angel V Peterchev
- Department of Biomedical Engineering, Duke University, Durham, NC, USA; Department of Psychiatry and Behavioural Sciences, Duke University, Durham, NC, USA; Department of Electrical and Computer Engineering, Duke University, Durham, NC, USA; Department of Neurosurgery, Duke University, Durham, NC, USA.
| | - Steve Vucic
- Brain and Nerve Research Centre, Concord Clinical School, University of Sydney, Concord Hospital, Sydney, Australia.
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Ranieri F, Mariotto S, Dubbioso R, Di Lazzaro V. Brain Stimulation as a Therapeutic Tool in Amyotrophic Lateral Sclerosis: Current Status and Interaction With Mechanisms of Altered Cortical Excitability. Front Neurol 2021; 11:605335. [PMID: 33613416 PMCID: PMC7892772 DOI: 10.3389/fneur.2020.605335] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 12/22/2020] [Indexed: 12/14/2022] Open
Abstract
In the last 20 years, several modalities of neuromodulation, mainly based on non-invasive brain stimulation (NIBS) techniques, have been tested as a non-pharmacological therapeutic approach to slow disease progression in amyotrophic lateral sclerosis (ALS). In both sporadic and familial ALS cases, neurophysiological studies point to motor cortical hyperexcitability as a possible priming factor in neurodegeneration, likely related to dysfunction of both excitatory and inhibitory mechanisms. A trans-synaptic anterograde mechanism of excitotoxicity is thus postulated, causing upper and lower motor neuron degeneration. Specifically, motor neuron hyperexcitability and hyperactivity are attributed to intrinsic cell abnormalities related to altered ion homeostasis and to impaired glutamate and gamma aminobutyric acid gamma-aminobutyric acid (GABA) signaling. Several neuropathological mechanisms support excitatory and synaptic dysfunction in ALS; additionally, hyperexcitability seems to drive DNA-binding protein 43-kDA (TDP-43) pathology, through the upregulation of unusual isoforms directly contributing to ASL pathophysiology. Corticospinal excitability can be suppressed or enhanced using NIBS techniques, namely, repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), as well as invasive brain and spinal stimulation. Experimental evidence supports the hypothesis that the after-effects of NIBS are mediated by long-term potentiation (LTP)-/long-term depression (LTD)-like mechanisms of modulation of synaptic activity, with different biological and physiological mechanisms underlying the effects of tDCS and rTMS and, possibly, of different rTMS protocols. This potential has led to several small trials testing different stimulation interventions to antagonize excitotoxicity in ALS. Overall, these studies suggest a possible efficacy of neuromodulation in determining a slight reduction of disease progression, related to the type, duration, and frequency of treatment, but current evidence remains preliminary. Main limitations are the small number and heterogeneity of recruited patients, the limited "dosage" of brain stimulation that can be delivered in the hospital setting, the lack of a sufficient knowledge on the excitatory and inhibitory mechanisms targeted by specific stimulation interventions, and the persistent uncertainty on the key pathophysiological processes leading to motor neuron loss. The present review article provides an update on the state of the art of neuromodulation in ALS and a critical appraisal of the rationale for the application/optimization of brain stimulation interventions, in the light of their interaction with ALS pathophysiological mechanisms.
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Affiliation(s)
- Federico Ranieri
- Neurology Unit, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Sara Mariotto
- Neurology Unit, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Raffaele Dubbioso
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University of Naples “Federico II”, Naples, Italy
| | - Vincenzo Di Lazzaro
- Unit of Neurology, Neurophysiology, Neurobiology, Department of Medicine, Campus Bio-Medico University, Rome, Italy
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Li CY, Yang TM, Ou RW, Wei QQ, Shang HF. Genome-wide genetic links between amyotrophic lateral sclerosis and autoimmune diseases. BMC Med 2021; 19:27. [PMID: 33541344 PMCID: PMC7863260 DOI: 10.1186/s12916-021-01903-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 01/05/2021] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Epidemiological and clinical studies have suggested comorbidity between amyotrophic lateral sclerosis (ALS) and autoimmune disorders. However, little is known about their shared genetic architecture. METHODS To examine the relation between ALS and 10 autoimmune diseases, including asthma, celiac disease (CeD), Crohn's disease (CD), inflammatory bowel disease (IBD), multiple sclerosis (MS), psoriasis, rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), type 1 diabetes (T1D), and ulcerative colitis (UC), and identify shared risk loci, we first estimated the genetic correlation using summary statistics from genome-wide association studies, and then analyzed the genetic enrichment leveraging the conditional false discovery rate statistical method. RESULTS We identified a significant positive genetic correlation between ALS and CeD, MS, RA, and SLE, as well as a significant negative genetic correlation between ALS and IBD, UC, and CD. Robust genetic enrichment was observed between ALS and CeD and MS, and moderate enrichment was found between ALS and UC and T1D. Thirteen shared genetic loci were identified, among which five were suggestively significant in another ALS GWAS, namely rs3828599 (GPX3), rs3849943 (C9orf72), rs7154847 (G2E3), rs6571361 (SCFD1), and rs9903355 (GGNBP2). By integrating cis-expression quantitative trait loci analyses in Braineac and GTEx, we further identified GGNBP2, ATXN3, and SLC9A8 as novel ALS risk genes. Functional enrichment analysis indicated that the shared risk genes were involved in four pathways including membrane trafficking, vesicle-mediated transport, ER to Golgi anterograde transport, and transport to the Golgi and subsequent modification. CONCLUSIONS Our findings demonstrate a specific genetic correlation between ALS and autoimmune diseases and identify shared risk loci, including three novel ALS risk genes. These results provide a better understanding for the pleiotropy of ALS and have implications for future therapeutic trials.
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Affiliation(s)
- Chun Yu Li
- Department of Neurology, Laboratory of Neurodegenerative Disorders, National Clinical Research Center for Geriatric, West China Hospital, Sichuan University, Chengdu, China
| | - Tian Mi Yang
- Department of Neurology, Laboratory of Neurodegenerative Disorders, National Clinical Research Center for Geriatric, West China Hospital, Sichuan University, Chengdu, China
| | - Ru Wei Ou
- Department of Neurology, Laboratory of Neurodegenerative Disorders, National Clinical Research Center for Geriatric, West China Hospital, Sichuan University, Chengdu, China
| | - Qian Qian Wei
- Department of Neurology, Laboratory of Neurodegenerative Disorders, National Clinical Research Center for Geriatric, West China Hospital, Sichuan University, Chengdu, China
| | - Hui Fang Shang
- Department of Neurology, Laboratory of Neurodegenerative Disorders, National Clinical Research Center for Geriatric, West China Hospital, Sichuan University, Chengdu, China.
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Portaro S, Biasini F, Bramanti P, Naro A, Calabrò RS. Chronic inflammatory demyelinating polyradiculoneuropathy relapse after mexiletine withdrawal in a patient with concomitant myotonia congenita: A case report on a potential treatment option. Medicine (Baltimore) 2020; 99:e21117. [PMID: 32664137 PMCID: PMC7360317 DOI: 10.1097/md.0000000000021117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
INTRODUCTION we report on the first case of a woman affected by chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and recessive myotonia congenita (MC), treated with mexiletine. We aimed at describing the possible role of mexiletine in CIDP management. PATIENT CONCERNS A 44-year-old female affected by CIDP and MC, gained beneficial effects for CIDP symptoms (muscle weakness, cramps, and fatigue) and relapses, after mexiletine intake (200 mg twice a day). The patient presented with detrimental effects after mexiletine drop out, with a worsening of CIDP symptoms. INTERVENTIONS The patient reported a nearly complete remission of muscle stiffness and weakness up to 3 years since mexiletine intake. Then, she developed an allergic reaction with glottis edema, maybe related to mexiletine intake, as per emergency room doctors' evaluation, who suggested withdrawing the drug. OUTCOMES The patient significantly worsened after the medication drop out concerning both CIDP and MC symptoms. CONCLUSION This is the first report on the association of CIDP and MC in the same patient. Such diseases may share some clinical symptoms related to a persistent sodium currents increase, which maybe due either to the over-expression of sodium channels following axonal damage due to demyelination or to the chloride channel genes mutations. This is the possible reason why mexiletine maybe promising to treat CIDP symptoms.
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Gunes ZI, Kan VWY, Ye X, Liebscher S. Exciting Complexity: The Role of Motor Circuit Elements in ALS Pathophysiology. Front Neurosci 2020; 14:573. [PMID: 32625051 PMCID: PMC7311855 DOI: 10.3389/fnins.2020.00573] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 05/11/2020] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal disease, characterized by the degeneration of both upper and lower motor neurons. Despite decades of research, we still to date lack a cure or disease modifying treatment, emphasizing the need for a much-improved insight into disease mechanisms and cell type vulnerability. Altered neuronal excitability is a common phenomenon reported in ALS patients, as well as in animal models of the disease, but the cellular and circuit processes involved, as well as the causal relevance of those observations to molecular alterations and final cell death, remain poorly understood. Here, we review evidence from clinical studies, cell type-specific electrophysiology, genetic manipulations and molecular characterizations in animal models and culture experiments, which argue for a causal involvement of complex alterations of structure, function and connectivity of different neuronal subtypes within the cortical and spinal cord motor circuitries. We also summarize the current knowledge regarding the detrimental role of astrocytes and reassess the frequently proposed hypothesis of glutamate-mediated excitotoxicity with respect to changes in neuronal excitability. Together, these findings suggest multifaceted cell type-, brain area- and disease stage- specific disturbances of the excitation/inhibition balance as a cardinal aspect of ALS pathophysiology.
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Affiliation(s)
- Zeynep I Gunes
- Institute of Clinical Neuroimmunology, Klinikum der Universität München, Ludwig Maximilians University Munich, Munich, Germany.,Graduate School of Systemic Neurosciences, Ludwig Maximilians University Munich, Munich, Germany.,Biomedical Center, Ludwig Maximilians University Munich, Munich, Germany
| | - Vanessa W Y Kan
- Institute of Clinical Neuroimmunology, Klinikum der Universität München, Ludwig Maximilians University Munich, Munich, Germany.,Graduate School of Systemic Neurosciences, Ludwig Maximilians University Munich, Munich, Germany.,Biomedical Center, Ludwig Maximilians University Munich, Munich, Germany
| | - XiaoQian Ye
- Institute of Clinical Neuroimmunology, Klinikum der Universität München, Ludwig Maximilians University Munich, Munich, Germany.,Biomedical Center, Ludwig Maximilians University Munich, Munich, Germany
| | - Sabine Liebscher
- Institute of Clinical Neuroimmunology, Klinikum der Universität München, Ludwig Maximilians University Munich, Munich, Germany.,Biomedical Center, Ludwig Maximilians University Munich, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
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8
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Weskamp K, Tank EM, Miguez R, McBride JP, Gómez NB, White M, Lin Z, Gonzalez CM, Serio A, Sreedharan J, Barmada SJ. Shortened TDP43 isoforms upregulated by neuronal hyperactivity drive TDP43 pathology in ALS. J Clin Invest 2020; 130:1139-1155. [PMID: 31714900 PMCID: PMC7269575 DOI: 10.1172/jci130988] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 11/06/2019] [Indexed: 12/13/2022] Open
Abstract
Cortical hyperexcitability and mislocalization of the RNA-binding protein TDP43 are highly conserved features in amyotrophic lateral sclerosis (ALS). Nevertheless, the relationship between these phenomena remains poorly defined. Here, we showed that hyperexcitability recapitulates TDP43 pathology by upregulating shortened TDP43 (sTDP43) splice isoforms. These truncated isoforms accumulated in the cytoplasm and formed insoluble inclusions that sequestered full-length TDP43 via preserved N-terminal interactions. Consistent with these findings, sTDP43 overexpression was toxic to mammalian neurons, suggesting neurodegeneration arising from complementary gain- and loss-of-function mechanisms. In humans and mice, sTDP43 transcripts were enriched in vulnerable motor neurons, and we observed a striking accumulation of sTDP43 within neurons and glia of ALS patients. Collectively, these studies uncover a pathogenic role for alternative TDP43 isoforms in ALS, and implicate sTDP43 as a key contributor to the susceptibility of motor neurons in this disorder.
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Affiliation(s)
| | | | | | - Jonathon P. McBride
- Department of Neurology
- Cellular and Molecular Biology Program, Michigan Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Nicolás B. Gómez
- Department of Neurology
- Cellular and Molecular Biology Program, Michigan Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Ziqiang Lin
- Department of Basic and Clinical Neuroscience and
| | - Carmen Moreno Gonzalez
- Centre for Craniofacial and Regenerative Biology, King’s College London, London, United Kingdom
| | - Andrea Serio
- Centre for Craniofacial and Regenerative Biology, King’s College London, London, United Kingdom
| | | | - Sami J. Barmada
- Department of Neurology
- Neuroscience Graduate Program, and
- Cellular and Molecular Biology Program, Michigan Medicine, University of Michigan, Ann Arbor, Michigan, USA
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Kiernan MC, Bostock H, Park SB, Kaji R, Krarup C, Krishnan AV, Kuwabara S, Lin CSY, Misawa S, Moldovan M, Sung J, Vucic S, Wainger BJ, Waxman S, Burke D. Measurement of axonal excitability: Consensus guidelines. Clin Neurophysiol 2019; 131:308-323. [PMID: 31471200 DOI: 10.1016/j.clinph.2019.07.023] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 07/17/2019] [Accepted: 07/24/2019] [Indexed: 12/12/2022]
Abstract
Measurement of axonal excitability provides an in vivo indication of the properties of the nerve membrane and of the ion channels expressed on these axons. Axonal excitability techniques have been utilised to investigate the pathophysiological mechanisms underlying neurological diseases. This document presents guidelines derived for such studies, based on a consensus of international experts, and highlights the potential difficulties when interpreting abnormalities in diseased axons. The present manuscript provides a state-of-the-art review of the findings of axonal excitability studies and their interpretation, in addition to suggesting guidelines for the optimal performance of excitability studies.
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Affiliation(s)
- Matthew C Kiernan
- Brain and Mind Centre, University of Sydney and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney 2006, Australia.
| | - Hugh Bostock
- UCL Queen Square Institute of Neurology, London WC1N 3BG, United Kingdom
| | - Susanna B Park
- Brain and Mind Centre, University of Sydney and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney 2006, Australia
| | - Ryuji Kaji
- National Utano Hospital, 8-Narutaki Ondoyamacho, Ukyoku, Kyoto 616-8255, Japan
| | - Christian Krarup
- Department of Neuroscience, University of Copenhagen and Department of Clinical Neurophysiology, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Arun V Krishnan
- Prince of Wales Clinical School, University of New South Wales, Sydney, Australia
| | - Satoshi Kuwabara
- Department of Neurology, Graduate School of Medicine, Chiba University, Japan
| | - Cindy Shin-Yi Lin
- Brain and Mind Centre, University of Sydney and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney 2006, Australia
| | - Sonoko Misawa
- Department of Neurology, Graduate School of Medicine, Chiba University, Japan
| | - Mihai Moldovan
- Department of Neuroscience, University of Copenhagen and Department of Clinical Neurophysiology, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Jiaying Sung
- Taipei Medical University, Wanfang Hospital, Taipei, Taiwan
| | - Steve Vucic
- Department of Neurology, Westmead Hospital, Western Clinical School, University of Sydney, Australia
| | - Brian J Wainger
- Department of Neurology and Anesthesiology, Critical Care & Pain Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Stephen Waxman
- Department of Neurology, Yale Medical School, New Haven, CT 06510, USA; Neurorehabilitation Research Center, Veterans Affairs Hospital, West Haven, CT 06516, USA
| | - David Burke
- Brain and Mind Centre, University of Sydney and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney 2006, Australia
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10
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Howells J, Matamala JM, Park SB, Garg N, Vucic S, Bostock H, Burke D, Kiernan MC. In vivo evidence for reduced ion channel expression in motor axons of patients with amyotrophic lateral sclerosis. J Physiol 2018; 596:5379-5396. [PMID: 30175403 DOI: 10.1113/jp276624] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 08/31/2018] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS The progressive loss of motor units in amyotrophic lateral sclerosis (ALS) is initially compensated for by the reinnervation of denervated muscle fibres by surviving motor axons. A disruption in protein homeostasis is thought to play a critical role in the pathogenesis of ALS. The changes in surviving motor neurons were studied by comparing the nerve excitability properties of moderately and severely affected single motor axons from patients with ALS with those from single motor axons in control subjects. A mathematical model indicated that approximately 99% of the differences between the ALS and control units could be explained by a non-selective reduction in the expression of all ion channels. These changes in ALS patients are best explained by a failure in the supply of ion channel and other membrane proteins from the diseased motor neuron. ABSTRACT Amyotrophic lateral sclerosis (ALS) is characterised by a progressive loss of motor units and the reinnervation of denervated muscle fibres by surviving motor axons. This reinnervation preserves muscle function until symptom onset, when some 60-80% of motor units have been lost. We have studied the changes in surviving motor neurons by comparing the nerve excitability properties of 31 single motor axons from patients with ALS with those from 21 single motor axons in control subjects. ALS motor axons were classified as coming from moderately or severely affected muscles according to the compound muscle action potential amplitude of the parent muscle. Compared with control units, thresholds were increased, and there was reduced inward and outward rectification and greater superexcitability following a conditioning impulse. These abnormalities were greater in axons from severely affected muscles, and were correlated with loss of fine motor skills. A mathematical model indicated that 99.1% of the differences between the moderately affected ALS and control units could be explained by a reduction in the expression of all ion channels. For the severely affected units, modelling required, in addition, an increase in the current leak through and under the myelin sheath. This might be expected if the anchoring proteins responsible for the paranodal seal were reduced. We conclude that changes in axonal excitability identified in ALS patients are best explained by a failure in the supply of ion channel and other membrane proteins from the diseased motor neuron, a conclusion consistent with recent animal and in vitro human data.
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Affiliation(s)
- James Howells
- Brain & Mind Centre, University of Sydney, Sydney, Australia
| | | | - Susanna B Park
- Brain & Mind Centre, University of Sydney, Sydney, Australia
| | - Nidhi Garg
- Brain & Mind Centre, University of Sydney, Sydney, Australia.,Institute of Clinical Neurosciences, Royal Prince Alfred Hospital and University of Sydney, Sydney, Australia
| | - Steve Vucic
- Departments of Neurology and Neurophysiology, Westmead Hospital and University of Sydney, Sydney, Australia
| | - Hugh Bostock
- MRC Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK.,Institute of Neurology, UCL, Queen Square, London, WC1N 3BG, UK
| | - David Burke
- Institute of Clinical Neurosciences, Royal Prince Alfred Hospital and University of Sydney, Sydney, Australia
| | - Matthew C Kiernan
- Brain & Mind Centre, University of Sydney, Sydney, Australia.,Institute of Clinical Neurosciences, Royal Prince Alfred Hospital and University of Sydney, Sydney, Australia
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11
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Oskarsson B, Moore D, Mozaffar T, Ravits J, Wiedau-Pazos M, Parziale N, Joyce NC, Mandeville R, Goyal N, Cudkowicz ME, Weiss M, Miller RG, McDonald CM. Mexiletine for muscle cramps in amyotrophic lateral sclerosis: A randomized, double-blind crossover trial. Muscle Nerve 2018; 58:10.1002/mus.26117. [PMID: 29510461 PMCID: PMC6126993 DOI: 10.1002/mus.26117] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/25/2018] [Indexed: 12/13/2022]
Abstract
INTRODUCTION More than 90% of amyotrophic lateral sclerosis (ALS) patients have muscle cramps, but evidence-based treatments have not been available. METHODS A multicenter, double-blind, placebo-controlled crossover trial of mexiletine 150 mg twice daily was conducted in ALS patients requesting treatment of symptomatic muscle cramps. RESULTS Muscle cramp frequency was reduced in 18 of 20 patients; 13 reductions were attributed to treatment (P < 0.05). The average reduction, based on t tests, was 1.8 cramps per day (a reduction from 5.3 with placebo to 3.5 with mexiletine). The estimated reduction of cramp severity was 15 units on a 100-unit scale (P = 0.01) from a baseline average of 46. No effect on fasciculations was noted. One patient discontinued the study because of dizziness, and another patient discontinued the study to start open-label mexiletine therapy. No serious adverse event occurred. DISCUSSION Mexiletine is a well tolerated and effective medication for controlling the symptom of muscle cramps in ALS. Muscle Nerve, 2018.
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Affiliation(s)
- Björn Oskarsson
- University of California, Davis, Sacramento, California, USA
| | - Dan Moore
- Pacific Medical Center, San Francisco, California, USA
| | | | - John Ravits
- University of California, San Diego, San Diego, California, USA
| | | | | | - Nanette C Joyce
- University of California, Davis, Sacramento, California, USA
| | - Ross Mandeville
- University of California, San Diego, San Diego, California, USA
| | - Namita Goyal
- University of California, Irvine, Irvine, California, USA
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12
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Maglemose R, Hedegaard A, Lehnhoff J, Dimintiyanova KP, Moldovan M, Grøndahl L, Meehan CF. Potassium channel abnormalities are consistent with early axon degeneration of motor axons in the G127X SOD1 mouse model of amyotrophic lateral sclerosis. Exp Neurol 2017; 292:154-167. [PMID: 28322742 DOI: 10.1016/j.expneurol.2017.03.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 02/21/2017] [Accepted: 03/14/2017] [Indexed: 12/12/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a lethal neurodegenerative disease, which selectively affects upper and lower motoneurones. The underlying pathophysiology of the disease is complex but electrophysiological studies of peripheral nerves in ALS patients as well as human autopsy studies indicate that a potassium channel dysfunction/loss is present early in the symptomatic phase. It remains unclear to what extent potassium channel abnormalities reflect a specific pathogenic mechanism in ALS. The aim of this study was therefore to investigate the temporal changes in the expression and/or function of potassium channels in motoneurones in the adult G127X SOD1 mouse model of ALS, a model which has a very long presymptomatic phase. Evidence from animal models indicates that the early progressive motoneurone dysfunction and degeneration can be largely compensated by motor unit remodeling, delaying the clinical symptom onset. Experiments were therefore performed both before and after symptom onset. Immunohistochemistry of motor axons in the ventral roots of G127X SOD1 mice, was used to investigate juxta-paranodal Kv1.2 potassium channels along with nodal Nav1.6 and the paranodal scaffolding protein Caspr. This allowed an investigation of changes in the distribution of Kv1.2 relative to the general structure of the nodal-paranodal-juxta-paranodal complex. This revealed that the motor axons in the ventral roots of presymptomatic G127X SOD1 mice, already show a disruption in juxta-paranodal Kv1.2 potassium channels. The axonal Kv1.2 disruption was preceded by abnormalities in the distribution of the paranodal scaffolding protein Caspr with the nodal arrangement of Nav1.6 appearing relatively preserved even in symptomatic mice. These changes were accompanied by axon swelling and a slowing of conduction in the peripheral motor axons in symptomatic mice. In vivo electrophysiological intracellular recordings of individual spinal motoneurones revealed that central potassium channel function was preserved or even enhanced with higher amplitude and longer duration after-hyperpolarisations in the G127X SOD1 mice. Our data suggest that the potassium channel abnormalities observed in presymptomatic G127X, rather than representing a specific pathophysiological mechanism targeting potassium channels, most likely reflect early axonal degenerative changes, consistent with the "dying-back" phenomenon observed in other ALS models.
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Affiliation(s)
- Rikke Maglemose
- Centre for Neuroscience, Copenhagen University, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Anne Hedegaard
- Centre for Neuroscience, Copenhagen University, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Janna Lehnhoff
- Centre for Neuroscience, Copenhagen University, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | | | - Mihai Moldovan
- Centre for Neuroscience, Copenhagen University, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Lillian Grøndahl
- Centre for Neuroscience, Copenhagen University, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Claire Francesca Meehan
- Centre for Neuroscience, Copenhagen University, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark.
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13
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Quantitative sensory testing and structural assessment of sensory nerve fibres in amyotrophic lateral sclerosis. J Neurol Sci 2017; 373:329-334. [DOI: 10.1016/j.jns.2017.01.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 12/12/2016] [Accepted: 01/03/2017] [Indexed: 11/22/2022]
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14
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Park SB, Kiernan MC, Vucic S. Axonal Excitability in Amyotrophic Lateral Sclerosis : Axonal Excitability in ALS. Neurotherapeutics 2017; 14:78-90. [PMID: 27878516 PMCID: PMC5233634 DOI: 10.1007/s13311-016-0492-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Axonal excitability testing provides in vivo assessment of axonal ion channel function and membrane potential. Excitability techniques have provided insights into the pathophysiological mechanisms underlying the development of neurodegeneration and clinical features of amyotrophic lateral sclerosis (ALS) and related neuromuscular disorders. Specifically, abnormalities of Na+ and K+ conductances contribute to development of membrane hyperexcitability in ALS, thereby leading to symptom generation of muscle cramps and fasciculations, in addition to promoting a neurodegenerative cascade via Ca2+-mediated processes. Modulation of axonal ion channel function in ALS has resulted in significant symptomatic improvement that has been accompanied by stabilization of axonal excitability parameters. Separately, axonal ion channel dysfunction evolves with disease progression and correlates with survival, thereby serving as a potential therapeutic biomarker in ALS. The present review provides an overview of axonal excitability techniques and the physiological mechanisms underlying membrane excitability, with a focus on the role of axonal ion channel dysfunction in motor neuron disease and related neuromuscular diseases.
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Affiliation(s)
- Susanna B Park
- Brain and Mind Centre, University of Sydney, Sydney, Australia
| | | | - Steve Vucic
- Westmead Clinical School, University of Sydney, Sydney, Australia.
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15
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Banzrai C, Nodera H, Kawarai T, Higashi S, Okada R, Mori A, Shimatani Y, Osaki Y, Kaji R. Impaired Axonal Na(+) Current by Hindlimb Unloading: Implication for Disuse Neuromuscular Atrophy. Front Physiol 2016; 7:36. [PMID: 26909041 PMCID: PMC4754663 DOI: 10.3389/fphys.2016.00036] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 01/26/2016] [Indexed: 12/12/2022] Open
Abstract
This study aimed to characterize the excitability changes in peripheral motor axons caused by hindlimb unloading (HLU), which is a model of disuse neuromuscular atrophy. HLU was performed in normal 8-week-old male mice by fixing the proximal tail by a clip connected to the top of the animal's cage for 3 weeks. Axonal excitability studies were performed by stimulating the sciatic nerve at the ankle and recording the compound muscle action potential (CMAP) from the foot. The amplitudes of the motor responses of the unloading group were 51% of the control amplitudes [2.2 ± 1.3 mV (HLU) vs. 4.3 ± 1.2 mV (Control), P = 0.03]. Multiple axonal excitability analysis showed that the unloading group had a smaller strength-duration time constant (SDTC) and late subexcitability (recovery cycle) than the controls [0.075 ± 0.01 (HLU) vs. 0.12 ± 0.01 (Control), P < 0.01; 5.4 ± 1.0 (HLU) vs. 10.0 ± 1.3 % (Control), P = 0.01, respectively]. Three weeks after releasing from HLU, the SDTC became comparable to the control range. Using a modeling study, the observed differences in the waveforms could be explained by reduced persistent Na+ currents along with parameters related to current leakage. Quantification of RNA of a SCA1A gene coding a voltage-gated Na+ channel tended to be decreased in the sciatic nerve in HLU. The present study suggested that axonal ion currents are altered in vivo by HLU. It is still undetermined whether the dysfunctional axonal ion currents have any pathogenicity on neuromuscular atrophy or are the results of neural plasticity by atrophy.
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Affiliation(s)
| | - Hiroyuki Nodera
- Department of Neurology, Tokushima University Tokushima, Japan
| | | | - Saki Higashi
- Department of Neurology, Tokushima University Tokushima, Japan
| | - Ryo Okada
- Department of Neurology, Tokushima University Tokushima, Japan
| | - Atsuko Mori
- Department of Neurology, Tokushima University Tokushima, Japan
| | | | - Yusuke Osaki
- Department of Neurology, Tokushima University Tokushima, Japan
| | - Ryuji Kaji
- Department of Neurology, Tokushima University Tokushima, Japan
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16
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Spalloni A, Longone P. Cognitive impairment in amyotrophic lateral sclerosis, clues from the SOD1 mouse. Neurosci Biobehav Rev 2016; 60:12-25. [DOI: 10.1016/j.neubiorev.2015.11.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 11/09/2015] [Accepted: 11/16/2015] [Indexed: 12/11/2022]
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17
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King AE, Woodhouse A, Kirkcaldie MT, Vickers JC. Excitotoxicity in ALS: Overstimulation, or overreaction? Exp Neurol 2016; 275 Pt 1:162-71. [DOI: 10.1016/j.expneurol.2015.09.019] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 08/30/2015] [Accepted: 09/28/2015] [Indexed: 12/14/2022]
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18
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Devlin AC, Burr K, Borooah S, Foster JD, Cleary EM, Geti I, Vallier L, Shaw CE, Chandran S, Miles GB. Human iPSC-derived motoneurons harbouring TARDBP or C9ORF72 ALS mutations are dysfunctional despite maintaining viability. Nat Commun 2015; 6:5999. [PMID: 25580746 PMCID: PMC4338554 DOI: 10.1038/ncomms6999] [Citation(s) in RCA: 207] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 11/28/2014] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease for which a greater understanding of early disease mechanisms is needed to reveal novel therapeutic targets. We report the use of human induced pluripotent stem cell (iPSC)-derived motoneurons (MNs) to study the pathophysiology of ALS. We demonstrate that MNs derived from iPSCs obtained from healthy individuals or patients harbouring TARDBP or C9ORF72 ALS-causing mutations are able to develop appropriate physiological properties. However, patient iPSC-derived MNs, independent of genotype, display an initial hyperexcitability followed by progressive loss of action potential output and synaptic activity. This loss of functional output reflects a progressive decrease in voltage-activated Na(+) and K(+) currents, which occurs in the absence of overt changes in cell viability. These data implicate early dysfunction or loss of ion channels as a convergent point that may contribute to the initiation of downstream degenerative pathways that ultimately lead to MN loss in ALS.
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Affiliation(s)
- Anna-Claire Devlin
- School of Psychology and Neuroscience, University of St. Andrews, Westburn Lane, St. Andrews KY16 9JP, UK
- Euan MacDonald Centre for Motor Neurone Disease Research, Edinburgh EH16 4SB, UK
| | - Karen Burr
- Euan MacDonald Centre for Motor Neurone Disease Research, Edinburgh EH16 4SB, UK
- Centre for Neuroregeneration and Medical Research Council Centre for Regenerative Medicine, University of Edinburgh, Edinburgh EH16 4UU, UK
| | - Shyamanga Borooah
- Euan MacDonald Centre for Motor Neurone Disease Research, Edinburgh EH16 4SB, UK
- Centre for Neuroregeneration and Medical Research Council Centre for Regenerative Medicine, University of Edinburgh, Edinburgh EH16 4UU, UK
| | - Joshua D. Foster
- School of Psychology and Neuroscience, University of St. Andrews, Westburn Lane, St. Andrews KY16 9JP, UK
| | - Elaine M. Cleary
- Euan MacDonald Centre for Motor Neurone Disease Research, Edinburgh EH16 4SB, UK
- Centre for Neuroregeneration and Medical Research Council Centre for Regenerative Medicine, University of Edinburgh, Edinburgh EH16 4UU, UK
| | - Imbisaat Geti
- Wellcome Trust-Medical Research Council Stem Cell Institute, Anne McLaren Laboratory for Regenerative Medicine, Department of Surgery, University of Cambridge, Cambridge CB2 0XY, UK
| | - Ludovic Vallier
- Wellcome Trust-Medical Research Council Stem Cell Institute, Anne McLaren Laboratory for Regenerative Medicine, Department of Surgery, University of Cambridge, Cambridge CB2 0XY, UK
| | - Christopher E. Shaw
- MRC Centre for Neurodegeneration Research, King’s College London, Institute of Psychiatry, De Crespigny Park, London SE5 8AF, UK
| | - Siddharthan Chandran
- Euan MacDonald Centre for Motor Neurone Disease Research, Edinburgh EH16 4SB, UK
- Centre for Neuroregeneration and Medical Research Council Centre for Regenerative Medicine, University of Edinburgh, Edinburgh EH16 4UU, UK
| | - Gareth B. Miles
- School of Psychology and Neuroscience, University of St. Andrews, Westburn Lane, St. Andrews KY16 9JP, UK
- Euan MacDonald Centre for Motor Neurone Disease Research, Edinburgh EH16 4SB, UK
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19
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Maxwell SK, Kokokyi S, Breiner A, Ebadi H, Bril V, Katzberg HD. Characteristics of muscle cramps in patients with polyneuropathy. Neuromuscul Disord 2014; 24:671-6. [PMID: 24878228 DOI: 10.1016/j.nmd.2014.04.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 04/04/2014] [Accepted: 04/24/2014] [Indexed: 11/17/2022]
Abstract
Muscle cramps are common in the general population and can be disabling for patients, but there is little evidence comprehensively evaluating cramp characteristics in patients with polyneuropathy. This study describes the prevalence and characteristics of muscle cramps in this patient group. Patients over 18 diagnosed with polyneuropathy were invited to join the study. Patients completed nerve conduction studies, the Toronto Clinical Neuropathy score, neuropathy-specific Vickrey's Quality of Life Assessment and a self-administered questionnaire examining demographics, neuropathy symptoms and cramp characteristics. Two hundred and twenty-five participants were enrolled (28.0% female). Sixty-three percent of patients experienced cramps, occurring on average 6 times per week, lasting 10.5 min and scoring 6 out of 10 on a pain scale and described as disabling by 43.6% of patients. No significant difference was found in cramp prevalence according to underlying pathophysiology (p = 0.52) or fiber type (p = 0.41). Patients with disabling cramps rated their physical (p < 0.0001) and mental (p = 0.04) quality of life lower than patients without disabling cramps. This study confirms that muscle cramps are common, disabling and associated with reduced quality of life in patients with polyneuropathy. Similar prevalence of cramps across predominant nerve fiber type suggests a role of sensory afferents in cramp generation, although this needs to be confirmed in larger cohorts.
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Affiliation(s)
- Sarah K Maxwell
- Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Seint Kokokyi
- Division of Neurology, University Health Network, Toronto, Ontario, Canada
| | - Ari Breiner
- Division of Neurology, University Health Network, Toronto, Ontario, Canada; Division of Neurology, University of Toronto, Toronto, Ontario, Canada
| | - Hamid Ebadi
- Division of Neurology, University Health Network, Toronto, Ontario, Canada; Division of Neurology, University of Toronto, Toronto, Ontario, Canada
| | - Vera Bril
- Division of Neurology, University Health Network, Toronto, Ontario, Canada; Division of Neurology, University of Toronto, Toronto, Ontario, Canada
| | - Hans D Katzberg
- Division of Neurology, University Health Network, Toronto, Ontario, Canada; Division of Neurology, University of Toronto, Toronto, Ontario, Canada.
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20
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Intrinsic membrane hyperexcitability of amyotrophic lateral sclerosis patient-derived motor neurons. Cell Rep 2014; 7:1-11. [PMID: 24703839 DOI: 10.1016/j.celrep.2014.03.019] [Citation(s) in RCA: 467] [Impact Index Per Article: 46.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 02/17/2014] [Accepted: 03/10/2014] [Indexed: 12/13/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease of the motor nervous system. We show using multielectrode array and patch-clamp recordings that hyperexcitability detected by clinical neurophysiological studies of ALS patients is recapitulated in induced pluripotent stem cell-derived motor neurons from ALS patients harboring superoxide dismutase 1 (SOD1), C9orf72, and fused-in-sarcoma mutations. Motor neurons produced from a genetically corrected but otherwise isogenic SOD1(+/+) stem cell line do not display the hyperexcitability phenotype. SOD1(A4V/+) ALS patient-derived motor neurons have reduced delayed-rectifier potassium current amplitudes relative to control-derived motor neurons, a deficit that may underlie their hyperexcitability. The Kv7 channel activator retigabine both blocks the hyperexcitability and improves motor neuron survival in vitro when tested in SOD1 mutant ALS cases. Therefore, electrophysiological characterization of human stem cell-derived neurons can reveal disease-related mechanisms and identify therapeutic candidates.
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21
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Koschnitzky JE, Quinlan KA, Lukas TJ, Kajtaz E, Kocevar EJ, Mayers WF, Siddique T, Heckman CJ. Effect of fluoxetine on disease progression in a mouse model of ALS. J Neurophysiol 2014; 111:2164-76. [PMID: 24598527 DOI: 10.1152/jn.00425.2013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Selective serotonin reuptake inhibitors (SSRIs) and other antidepressants are often prescribed to amyotrophic lateral sclerosis (ALS) patients; however, the impact of these prescriptions on ALS disease progression has not been systematically tested. To determine whether SSRIs impact disease progression, fluoxetine (Prozac, 5 or 10 mg/kg) was administered to mutant superoxide dismutase 1 (SOD1) mice during one of three age ranges: neonatal [postnatal day (P)5-11], adult presymptomatic (P30 to end stage), and adult symptomatic (P70 to end stage). Long-term adult fluoxetine treatment (started at either P30 or P70 and continuing until end stage) had no significant effect on disease progression. In contrast, neonatal fluoxetine treatment (P5-11) had two effects. First, all animals (mutant SOD1(G93A) and control: nontransgenic and SOD1(WT)) receiving the highest dose (10 mg/kg) had a sustained decrease in weight from P30 onward. Second, the high-dose SOD1(G93A) mice reached end stage ∼8 days (∼6% decrease in life span) sooner than vehicle and low-dose animals because of an increased rate of motor impairment. Fluoxetine increases synaptic serotonin (5-HT) levels, which is known to increase spinal motoneuron excitability. We confirmed that 5-HT increases spinal motoneuron excitability during this neonatal time period and therefore hypothesized that antagonizing 5-HT receptors during the same time period would improve disease outcome. However, cyproheptadine (1 or 5 mg/kg), a 5-HT receptor antagonist, had no effect on disease progression. These results show that a brief period of antidepressant treatment during a critical time window (the transition from neonatal to juvenile states) can be detrimental in ALS mouse models.
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Affiliation(s)
- J E Koschnitzky
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - K A Quinlan
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - T J Lukas
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - E Kajtaz
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - E J Kocevar
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - W F Mayers
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - T Siddique
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University Feinberg School of Medicine, Chicago, Illinois; and
| | - C J Heckman
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois; Department of Physical Medicine and Rehabilitation, Northwestern University Feinberg School of Medicine, Chicago, Illinois
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22
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Caioli S, Pieri M, Antonini A, Guglielmotti A, Severini C, Zona C. Monocyte Chemoattractant Protein-1 upregulates GABA-induced current: Evidence of modified GABAA subunit composition in cortical neurons from the G93A mouse model of Amyotrophic Lateral Sclerosis. Neuropharmacology 2013; 73:247-60. [DOI: 10.1016/j.neuropharm.2013.05.045] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 05/06/2013] [Accepted: 05/27/2013] [Indexed: 02/06/2023]
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23
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Shibuta Y, Shimatani Y, Nodera H, Izumi Y, Kaji R. Increased variability of axonal excitability in amyotrophic lateral sclerosis. Clin Neurophysiol 2013; 124:2046-53. [PMID: 23726502 DOI: 10.1016/j.clinph.2013.02.117] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 01/30/2013] [Accepted: 02/18/2013] [Indexed: 10/26/2022]
Abstract
OBJECTIVE Amyotrophic lateral sclerosis (ALS) is characterised by the increased excitability of motoneurons and heterogeneous loss of axons. The heterogeneous nature of the disease process among fibres may show variability of excitability in ALS. METHODS Multiple nerve excitability tests were performed in 28 ALS patients and 23 control subjects, by tracking at the varying threshold levels (10%, 20%, 40% and 60% of maximum amplitudes). RESULTS In normal controls, excitability measures at low target levels have the following characteristics compared to those at high target levels: longer strength-duration time constant, greater threshold reduction during depolarising currents and smaller threshold increase to hyperpolarising currents. ALS patients had less clear amplitude dependency of the parameters than the controls, indicating variability of axonal excitability. Three ALS patients demonstrated greater target-amplitude-dependent threshold changes in threshold electrotonus than controls, suggesting selective axonal hyperexcitability. CONCLUSIONS Some of the ALS patients had variable axonal excitability at different target amplitudes, suggesting preferential hyperexcitability in the axons with low target amplitude levels. SIGNIFICANCE Variable membrane potentials of motor axons in ALS may be assessed by recording excitability testing at different target amplitude levels.
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Affiliation(s)
- Yoshiko Shibuta
- Department of Neurology, Tokushima University, Tokushima, Japan
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24
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Cheah BC, Lin CS, Park SB, Vucic S, Krishnan AV, Kiernan MC. Progressive axonal dysfunction and clinical impairment in amyotrophic lateral sclerosis. Clin Neurophysiol 2012; 123:2460-7. [DOI: 10.1016/j.clinph.2012.06.020] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 05/22/2012] [Accepted: 06/06/2012] [Indexed: 01/01/2023]
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25
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Batt J, dos Santos CC, Cameron JI, Herridge MS. Intensive care unit-acquired weakness: clinical phenotypes and molecular mechanisms. Am J Respir Crit Care Med 2012. [PMID: 23204256 DOI: 10.1164/rccm.201205-0954so] [Citation(s) in RCA: 155] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Intensive care unit-acquired weakness (ICUAW) begins within hours of mechanical ventilation and may not be completely reversible over time. It represents a major functional morbidity of critical illness and is an important patient-centered outcome with clear implications for quality of life and resumption of prior work and lifestyle. There is heterogeneity in functional outcome related to ICUAW across various patient populations after an episode of critical illness. This state-of-the art review argues that this observed heterogeneity may represent a clinical spectrum of disability in which there are recognizable clinical phenotypes for outcome according to age, burden of comorbid illness, and ICU length of stay. It further argues that these functional outcomes are modified by mood, cognition, and caregiver physical and mental health. This proposed construct of clinical phenotypes will be used as a framework for a review of the current literature on the molecular biology of muscle and nerve injury. This translational approach for the development of models pairing clinical phenotypes for different functional outcomes after critical illness with molecular mechanism of injury may offer unique insights into the diagnosis and treatment of muscle and nerve lesions.
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Affiliation(s)
- Jane Batt
- Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada.
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26
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Over-expression of N-type calcium channels in cortical neurons from a mouse model of Amyotrophic Lateral Sclerosis. Exp Neurol 2012; 247:349-58. [PMID: 23142186 DOI: 10.1016/j.expneurol.2012.11.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Revised: 10/24/2012] [Accepted: 11/02/2012] [Indexed: 12/13/2022]
Abstract
Voltage-gated Ca(2+) channels (VGCCs) mediate calcium entry into neuronal cells in response to membrane depolarisation and play an essential role in a variety of physiological processes. In Amyotrophic Lateral Sclerosis (ALS), a fatal neurodegenerative disease caused by motor neuron degeneration in the brain and spinal cord, intracellular calcium dysregulation has been shown, while no studies have been carried out on VGCCs. Here we show that the subtype N-type Ca(2+) channels are over expressed in G93A cultured cortical neurons and in motor cortex of G93A mice compared to Controls. In fact, by western blotting, immunocytochemical and electrophysiological experiments, we observe higher membrane expression of N-type Ca(2+) channels in G93A neurons compared to Controls. G93A cortical neurons filled with calcium-sensitive dye Fura-2, show a net calcium entry during membrane depolarization that is significantly higher compared to Control. Analysis of neuronal vitality following the exposure of neurons to a high K(+) concentration (25 mM, 5h), shows a significant reduction of G93A cellular survival compared to Controls. N-type channels are involved in the G93A higher mortality because ω-conotoxin GVIA (1 μM), which selectively blocks these channels, is able to abolish the higher G93A mortality when added to the external medium. These data provide robust evidence for an excess of N-type Ca(2+) expression in G93A cortical neurons which induces a higher mortality following membrane depolarization. These results may be central to the understanding of pathogenic pathways in ALS and provide novel molecular targets for the design of rational therapies for the ALS disorder.
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Dengler R, Petri S. Changes in motor axon K(+) conductance in ALS. Primary or secondary to motor neuron degeneration? Clin Neurophysiol 2012; 123:2326-7. [PMID: 22901336 DOI: 10.1016/j.clinph.2012.07.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2012] [Revised: 07/11/2012] [Accepted: 07/19/2012] [Indexed: 11/30/2022]
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Changes of the peripheral nerve excitability in vivo induced by the persistent Na+ current blocker ranolazine. Neurosci Lett 2012; 518:36-40. [DOI: 10.1016/j.neulet.2012.04.050] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 04/10/2012] [Accepted: 04/19/2012] [Indexed: 02/01/2023]
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29
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Moldovan M, Alvarez S, Pinchenko V, Marklund S, Graffmo KS, Krarup C. Nerve excitability changes related to axonal degeneration in amyotrophic lateral sclerosis: Insights from the transgenic SOD1G127X mouse model. Exp Neurol 2012; 233:408-20. [DOI: 10.1016/j.expneurol.2011.11.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 09/16/2011] [Accepted: 11/07/2011] [Indexed: 12/13/2022]
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Kumar KR, Sue CM, Burke D, Ng K. Peripheral neuropathy in hereditary spastic paraplegia due to spastin (SPG4) mutation--a neurophysiological study using excitability techniques. Clin Neurophysiol 2011; 123:1454-9. [PMID: 22192498 DOI: 10.1016/j.clinph.2011.11.080] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Revised: 11/15/2011] [Accepted: 11/22/2011] [Indexed: 10/14/2022]
Abstract
OBJECTIVE To identify peripheral nerve abnormalities in hereditary spastic paraplegia (HSP) due to mutations in the spastin gene (spastic paraplegia 4, SPG4) using standard nerve conduction (NCS) and novel tests of axonal excitability. METHODS Eleven patients with known mutations in spastin were assessed with NCS for the upper and lower limbs, and axonal excitability testing on the median nerve. RESULTS Standard nerve conduction studies revealed a sensorimotor neuropathy in two patients. Excitability studies on median motor axons showed an isolated abnormality (increased strength-duration time constant), but those on sensory axons were normal in nine patients with normal routine nerve conduction studies. CONCLUSIONS Peripheral neuropathy occurs in HSP patients with SPG4 mutations, but axonal excitability studies provide limited additional evidence for subclinical peripheral nerve dysfunction, and add little further to standard nerve conduction studies. SIGNIFICANCE The features of HSP due to SPG4 mutations include sensorimotor polyneuropathy. The value of excitability studies is limited in individual patients.
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Affiliation(s)
- Kishore R Kumar
- Department of Neurology and Clinical Neurophysiology, Royal North Shore Hospital, St Leonards, NSW 2065, Australia
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Shimatani Y, Shibuta Y, Nodera H, Nodera A, Asanuma K, Izumi Y, Kaji R. [Increased variability of membrane potentials in amyotrophic lateral sclerosis]. Rinsho Shinkeigaku 2011; 51:1114-1117. [PMID: 22277501 DOI: 10.5692/clinicalneurol.51.1114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is characterized by increased excitability of motor neurons and early involvement of large motor fibers that have low electrical thresholds. Despite the advent of new techniques of threshold tracking, exploration of this abnormal excitability has not been straightforward, by tracking at the single target level as previous reported, because of the heterogeneous nature of the disease process among fibers that have variable thresholds. We have assessed different populations of motor axons by tracking at four different target response levels (10, 20, 40 and 60% of maximum compound muscle action potentials), and conducted multiple nerve excitability tests in 27 ALS patients and 23 control subjects. In normal controls, axons with low thresholds have the following characteristics compared to those with high thresholds: greater threshold reduction during depolarizing currents and smaller threshold increase to hyperpolarizing currents, reflecting the order of the fiber size. In contrast, ALS patients lacked these relationships, suggesting increased variability of axonal membrane potentials. Three ALS patients demonstrated changes in threshold electrotonus, consistent with overt membrane depolarization, as seen in ischemic nerves. The variability of motor nerve excitability accounts for fasciculations, confirms previously reported dysfunction of potassium channels, and suggests failure of Na(+)/K(+)pumps, possibly caused by mitochondrial dysfunctions at the early stage.
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Bellingham MC. A review of the neural mechanisms of action and clinical efficiency of riluzole in treating amyotrophic lateral sclerosis: what have we learned in the last decade? CNS Neurosci Ther 2011; 17:4-31. [PMID: 20236142 DOI: 10.1111/j.1755-5949.2009.00116.x] [Citation(s) in RCA: 259] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating and fatal neurodegenerative disease of adults which preferentially attacks the neuromotor system. Riluzole has been used as the only approved treatment for amyotrophic lateral sclerosis since 1995, but its mechanism(s) of action in slowing the progression of this disease remain obscure. Searching PubMed for "riluzole" found 705 articles published between January 1996 and June 2009. A systematic review of this literature found that riluzole had a wide range of effects on factors influencing neural activity in general, and the neuromotor system in particular. These effects occurred over a large dose range (<1 μM to >1 mM). Reported neural effects of riluzole included (in approximate ascending order of dose range): inhibition of persistent Na(+) current = inhibition of repetitive firing < potentiation of calcium-dependent K(+) current < inhibition of neurotransmitter release < inhibition of fast Na(+) current < inhibition of voltage-gated Ca(2+) current = promotion of neuronal survival or growth factors < inhibition of voltage-gated K(+) current = modulation of two-pore K(+) current = modulation of ligand-gated neurotransmitter receptors = potentiation of glutamate transporters. Only the first four of these effects commonly occurred at clinically relevant concentrations of riluzole (plasma levels of 1-2 μM with three- to four-fold higher concentrations in brain tissue). Treatment of human ALS patients or transgenic rodent models of ALS with riluzole most commonly produced a modest but significant extension of lifespan. Riluzole treatment was well tolerated in humans and animals. In animals, despite in vitro evidence that riluzole may inhibit rhythmic motor behaviors, in vivo administration of riluzole produced relatively minor effects on normal respiration parameters, but inhibited hypoxia-induced gasping. This effect may have implications for the management of hypoventilation and sleep-disordered breathing during end-stage ALS in humans.
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Affiliation(s)
- Mark C Bellingham
- School of Biomedical Sciences, University of Queensland, Brisbane, Qld. 4072, Australia.
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Sawai S, Misawa S, Kanai K, Isose S, Shibuya K, Noto Y, Fujimaki Y, Sekiguchi Y, Nasu S, Nomura F, Kuwabara S. Altered axonal excitability properties in juvenile muscular atrophy of distal upper extremity (Hirayama disease). Clin Neurophysiol 2011; 122:205-9. [DOI: 10.1016/j.clinph.2010.06.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2010] [Revised: 06/17/2010] [Accepted: 06/19/2010] [Indexed: 11/24/2022]
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Meehan CF, Moldovan M, Marklund SL, Graffmo KS, Nielsen JB, Hultborn H. Intrinsic properties of lumbar motor neurones in the adult G127insTGGG superoxide dismutase-1 mutant mouse in vivo: evidence for increased persistent inward currents. Acta Physiol (Oxf) 2010; 200:361-76. [PMID: 20874803 DOI: 10.1111/j.1748-1716.2010.02188.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
AIM Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by a preferential loss of motor neurones. Previous publications using in vitro neonatal preparations suggest an increased excitability of motor neurones in various superoxide dismutase-1 (SOD1) mutant mice models of ALS which may contribute to excitotoxicity of the motor neurones. METHODS Using intracellular recording, we tested this hypothesis in vivo in the adult presymptomatic G127insTGGG (G127X) SOD1 mutant mouse model of ALS. RESULTS At resting membrane potentials the basic intrinsic properties of lumbar motor neurones in the adult presymptomatic G127X mutant are not significantly different from those of wild type. However, at more depolarized membrane potentials, motor neurones in the G127X SOD1 mutants can sustain higher frequency firing, showing less spike frequency adaption (SFA) and with persistent inward currents (PICs) being activated at lower firing frequencies and being more pronounced. CONCLUSION We demonstrated that, in vivo, at resting membrane potential, spinal motor neurones of the adult G127X mice do not show an increased excitability. However, when depolarized they show evidence of an increased PIC and less SFA which may contribute to excitotoxicity of these neurones as the disease progresses.
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Affiliation(s)
- C F Meehan
- Department of Neuroscience and Pharmacology, Panum Institute, University of Copenhagen, Denmark.
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Carunchio I, Curcio L, Pieri M, Pica F, Caioli S, Viscomi MT, Molinari M, Canu N, Bernardi G, Zona C. Increased levels of p70S6 phosphorylation in the G93A mouse model of Amyotrophic Lateral Sclerosis and in valine-exposed cortical neurons in culture. Exp Neurol 2010; 226:218-30. [DOI: 10.1016/j.expneurol.2010.08.033] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Revised: 08/30/2010] [Accepted: 08/30/2010] [Indexed: 12/11/2022]
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ElBasiouny SM, Schuster JE, Heckman CJ. Persistent inward currents in spinal motoneurons: important for normal function but potentially harmful after spinal cord injury and in amyotrophic lateral sclerosis. Clin Neurophysiol 2010; 121:1669-79. [PMID: 20462789 PMCID: PMC3000632 DOI: 10.1016/j.clinph.2009.12.041] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Revised: 11/28/2009] [Accepted: 12/14/2009] [Indexed: 10/19/2022]
Abstract
Meaningful body movements depend on the interplay between synaptic inputs to motoneurons and their intrinsic properties. Injury and disease often alter either or both of these factors and cause motoneuron and movement dysfunction. The ability of the motoneuronal membrane to generate persistent inward currents (PICs) is especially potent in setting the intrinsic excitability of motoneurons and can drastically change the motoneuron output to a given input. In this article, we review the role of PICs in modulating the excitability of spinal motoneurons during health, and their contribution to motoneuron excitability after spinal cord injury (SCI) and in amyotrophic lateral sclerosis (ALS) leading to exaggerated long-lasting reflexes and muscle spasms, and contributing to neuronal degeneration, respectively.
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Affiliation(s)
- S M ElBasiouny
- Physiology, Physical Medicine and Rehabilitation, Physical Therapy and Human Movement Sciences, Northwestern University, Feinberg School of Medicine, Chicago, IL, United States
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37
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Mexiletine suppresses nodal persistent sodium currents in sensory axons of patients with neuropathic pain. Clin Neurophysiol 2010; 121:719-24. [DOI: 10.1016/j.clinph.2009.12.034] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2009] [Revised: 12/23/2009] [Accepted: 12/24/2009] [Indexed: 11/17/2022]
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38
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Boërio D, Créange A, Hogrel JY, Guéguen A, Bertrand D, Lefaucheur JP. Nerve excitability changes after intravenous immunoglobulin infusions in multifocal motor neuropathy and chronic inflammatory demyelinating neuropathy. J Neurol Sci 2010; 292:63-71. [DOI: 10.1016/j.jns.2010.02.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2009] [Revised: 12/22/2009] [Accepted: 02/02/2010] [Indexed: 10/19/2022]
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Misawa S, Sakurai K, Shibuya K, Isose S, Kanai K, Ogino J, Ishikawa K, Kuwabara S. Neuropathic pain is associated with increased nodal persistent Na(+) currents in human diabetic neuropathy. J Peripher Nerv Syst 2010; 14:279-84. [PMID: 20021569 DOI: 10.1111/j.1529-8027.2009.00239.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Peripheral nerve injury alters function and expression of voltage gated Na(+) channels on the axolemma, leading to ectopic firing and neuropathic pain/paresthesia. Hyperglycemia also affects nodal Na(+) currents, presumably due to activation of polyol pathway and impaired Na(+)-K(+) pump. We investigated changes in nodal Na(+) currents in peripheral sensory axons and their relation with pain in human diabetic neuropathy. Latent addition using computerized threshold tracking was used to estimate nodal persistent Na(+) currents in radial sensory axons of 81 diabetic patients. Of these, 36 (44%) had chronic neuropathic pain and severe paresthesia. Compared to patients without pain, those with pain had greater nodal Na(+) currents (p = 0.001), smaller amplitudes of sensory nerve action potentials (SNAP) (p = 0.0003), and lower hemoglobin A1c levels (p = 0.006). Higher axonal Na(+) conductance was associated with smaller SNAP amplitudes (p = 0.03) and lower hemoglobin A1c levels (p = 0.008). These results suggest that development of neuropathic pain depends on axonal hyperexcitability due to increased nodal Na(+) currents associated with structural changes, but the currents could also be affected by the state of glycemic control. Our findings support the view that altered Na(+) channels could be responsible for neuropathic pain/paresthesia in diabetic neuropathy.
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Affiliation(s)
- Sonoko Misawa
- Department of Neurology, Chiba University Graduate School of Medicine, Chuo-ku, Chiba, Japan.
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40
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Boërio D, Kalmar B, Greensmith L, Bostock H. Excitability properties of mouse motor axons in the mutant SOD1G93A
model of amyotrophic lateral sclerosis. Muscle Nerve 2010; 41:774-84. [DOI: 10.1002/mus.21579] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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41
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Corticomotoneuronal dysfunction: A process specific to amyotrophic lateral sclerosis? Clin Neurophysiol 2009; 120:1881-1882. [DOI: 10.1016/j.clinph.2009.08.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 08/11/2009] [Accepted: 08/11/2009] [Indexed: 12/13/2022]
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42
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Krishnan AV, Lin CSY, Park SB, Kiernan MC. Axonal ion channels from bench to bedside: a translational neuroscience perspective. Prog Neurobiol 2009; 89:288-313. [PMID: 19699774 DOI: 10.1016/j.pneurobio.2009.08.002] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Revised: 08/17/2009] [Accepted: 08/17/2009] [Indexed: 12/13/2022]
Abstract
Over recent decades, the development of specialised techniques such as patch clamping and site-directed mutagenesis have established the contribution of neuronal ion channel dysfunction to the pathophysiology of common neurological conditions including epilepsy, multiple sclerosis, spinal cord injury, peripheral neuropathy, episodic ataxia, amyotrophic lateral sclerosis and neuropathic pain. Recently, these insights from in vitro studies have been translated into the clinical realm. In keeping with this progress, novel clinical axonal excitability techniques have been developed to provide information related to the activity of a variety of ion channels, energy-dependent pumps and ion exchange processes activated during impulse conduction in peripheral axons. These non-invasive techniques have been extensively applied to the study of the biophysical properties of human peripheral nerves in vivo and have provided important insights into axonal ion channel function in health and disease. This review will provide a translational perspective, focusing on an overview of the investigational method, the clinical utility in assessing the biophysical basis of ectopic symptom generation in peripheral nerve disease and a review of the major findings of excitability studies in acquired and inherited neurological disease states.
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Affiliation(s)
- Arun V Krishnan
- Translational Neuroscience Facility, University of New South Wales, Randwick, Sydney, NSW, Australia
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43
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Complex intrinsic membrane properties and dopamine shape spiking activity in a motor axon. J Neurosci 2009; 29:5062-74. [PMID: 19386902 DOI: 10.1523/jneurosci.0716-09.2009] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We studied the peripheral motor axons of the two pyloric dilator (PD) neurons of the stomatogastric ganglion in the lobster, Homarus americanus. Intracellular recordings from the motor nerve showed both fast and slow voltage- and activity-dependent dynamics. During rhythmic bursts, the PD axons displayed changes in spike amplitude and duration. Pharmacological experiments and the voltage dependence of these phenomena suggest that inactivation of sodium and A-type potassium channels are responsible. In addition, the "resting" membrane potential was dependent on ongoing spike or burst activity, with more hyperpolarized values when activity was strong. Nerve stimulations, pharmacological block and current clamp experiments suggest that this is due to a functional antagonism between a slow after-hyperpolarization (sAHP) and inward rectification through hyperpolarization-activated current (IH). Dopamine application resulted in modest depolarization and "ectopic" peripheral spike initiation in the absence of centrally generated activity. This effect was blocked by CsCl and ZD7288, consistent with a role of IH. High frequency nerve stimulation inhibited peripheral spike initiation for several seconds, presumably due to the sAHP. Both during normal bursting activity and antidromic nerve stimulation, the conduction delay over the length of the peripheral nerve changed in a complex manner. This suggests that axonal membrane dynamics can have a substantial effect on the temporal fidelity of spike patterns propagated from a spike initiation site to a synaptic target, and that neuromodulators can influence the extent to which spike patterns are modified.
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44
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Pieri M, Carunchio I, Curcio L, Mercuri NB, Zona C. Increased persistent sodium current determines cortical hyperexcitability in a genetic model of amyotrophic lateral sclerosis. Exp Neurol 2009; 215:368-79. [DOI: 10.1016/j.expneurol.2008.11.002] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Revised: 11/06/2008] [Accepted: 11/08/2008] [Indexed: 12/11/2022]
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45
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Piotrkiewicz M, Kudina L, Mierzejewska J, Hausmanowa-Petrusewicz I. Analysis of double discharges in amyotrophic lateral sclerosis. Muscle Nerve 2008; 38:845-54. [PMID: 18508341 DOI: 10.1002/mus.20997] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Double discharges of motor units (MUs) occurring during sustained voluntary muscle contractions are observed occasionally in healthy muscles and more frequently in disorders of the neuromuscular system. In healthy subjects, double discharges are generated in motoneurons (MNs) and are considered to be a sign of their increased excitability. Therefore, an analysis of their firing pattern may provide information on the state of MNs in neuromuscular diseases, particularly in amyotrophic lateral sclerosis (ALS), whose etiology remains to be disclosed. Firing patterns of MUs capable of firing double discharges were analyzed in brachial biceps of 14 patients with ALS (184 MUs) and 8 healthy control subjects (102 MUs). The incidence of MUs capable of firing double discharges was significantly higher in ALS patients (28.8%) than in controls (3.9%). The majority of doublet interval durations (range 4-8 ms) as well as firing patterns of doubling MUs did not differ between subject groups. Although our data confirm the hyperexcitability of the MN pool in ALS, analysis of firing characteristics of doubling MUs indicates that doublet generation is governed by the same mechanism as in controls, that is, by delayed depolarization. Our findings may provide insight into MN function in ALS.
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Affiliation(s)
- Maria Piotrkiewicz
- Bionics Department, Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, 4 Ks. Trojdena Str., Warsaw, Poland.
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46
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Bae JS, Sawai S, Misawa S, Kanai K, Isose S, Shibuya K, Kuwabara S. Effects of age on excitability properties in human motor axons. Clin Neurophysiol 2008; 119:2282-6. [PMID: 18760964 DOI: 10.1016/j.clinph.2008.07.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2008] [Revised: 07/09/2008] [Accepted: 07/20/2008] [Indexed: 10/21/2022]
Abstract
OBJECTIVE The threshold tracking technique is a new approach to non-invasively assess biophysical properties of axonal membrane in human subjects. The aim of this study was to evaluate the effects of age and gender on excitability properties of human motor axons. METHODS Computerized threshold tracking was used to measure multiple excitability indices in median motor axons of 93 normal subjects (50 men; age, 20-86 years). RESULTS Regression analyses showed that the higher age was associated with longer strength-duration time constant (p=0.03), smaller threshold changes in depolarizing threshold electrotonus (p=0.02), smaller supernormality (p=0.01), and steeper slope of the current-threshold relationship for hyperpolarizing currents (p<0.001). There were slight sex differences in rheobase, threshold electrotonus, supernormality, late subnormality, and current-threshold slope, though they were significant only in the subgroup with age <50 years. CONCLUSIONS Aging may increase persistent sodium currents, inward rectification, and possibly, outward potassium currents. The combination of changes raises the possibility of slight membrane depolarization in elderly people. For the sex-related differences, further studies will be required with the evaluation of sex hormonal effects. SIGNIFICANCE Age-related effects on excitability properties are subtle, but should be taken into consideration in the clinical application of nerve excitability testing, particularly in elderly subjects.
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Affiliation(s)
- Jong Seok Bae
- Department of Neurology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan
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Nakata M, Baba H, Kanai K, Hoshi T, Sawai S, Hattori T, Kuwabara S. Changes in Na(+) channel expression and nodal persistent Na(+) currents associated with peripheral nerve regeneration in mice. Muscle Nerve 2008; 37:721-30. [PMID: 18506710 DOI: 10.1002/mus.21031] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Patients with peripheral neuropathy frequently suffer from positive sensory (pain and paresthesias) and motor (muscle cramping) symptoms even in the recovery phase of the disease. To investigate the pathophysiology of increased axonal excitability in peripheral nerve regeneration, we assessed the temporal and spatial expression of voltage-gated Na(+) channels as well as nodal persistent Na(+) currents in a mouse model of Wallerian degeneration. Crushed sciatic nerves of 8-week-old C57/BL6J male mice underwent complete Wallerian degeneration at 1 week. Two weeks after crush, there was a prominent increase in the number of Na(+) channel clusters per unit area, and binary or broad Na(+) channel clusters were frequently found. Excess Na(+) channel clusters were retained up to 20 weeks post-injury. Excitability testing using latent addition suggested that nodal persistent Na(+) currents markedly increased beginning at week 3, and remained through week 10. These results suggest that axonal regeneration is associated with persistently increased axonal excitability resulting from increases in the number and conductance of Na(+) channels.
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Affiliation(s)
- Miho Nakata
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba 260-8670, Japan
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48
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Moldovan M, Alvarez S, Krarup C. Motor axon excitability during Wallerian degeneration. Brain 2008; 132:511-23. [DOI: 10.1093/brain/awn332] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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49
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Hegedus J, Putman CT, Tyreman N, Gordon T. Preferential motor unit loss in the SOD1 G93A transgenic mouse model of amyotrophic lateral sclerosis. J Physiol 2008; 586:3337-51. [PMID: 18467368 DOI: 10.1113/jphysiol.2007.149286] [Citation(s) in RCA: 182] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The present study investigated motor unit (MU) loss in a murine model of familial amyotrophic lateral sclerosis (ALS). The fast-twitch tibialis anterior (TA) and medial gastrocnemius (MG) muscles of transgenic SOD1(G93A) and SOD1(WT) mice were studied during the presymptomatic phase of disease progression at 60 days of age. Whole muscle maximum isometric twitch and tetanic forces were 80% lower (P < 0.01) in the TA muscles of SOD1(G93A) compared to SOD1(WT) mice. Enumeration of total MU numbers within TA muscles showed a 60% reduction (P < 0.01) within SOD1(G93A) mice (38 +/- 7) compared with SOD1(WT) controls (95 +/- 12); this was attributed to a lower proportion of the most forceful fast-fatigable (FF) MU in SOD1(G93A) mice, as seen by a significant (P < 0.01) leftward shift in the cumulative frequency histogram of single MU forces. Similar patterns of MU loss and corresponding decreases in isometric twitch force were observed in the MG. Immunocytochemical analyses of the entire cross-sectional area (CSA) of serial sections of TA muscles stained with anti-neural cell adhesion molecule (NCAM) and various monoclonal antibodies for myosin heavy chain (MHC) isoforms showed respective 65% (P < 0.01) and 28% (P < 0.05) decreases in the number of innervated IIB and IID/X muscle fibres in SOD1(G93A), which paralleled the 60% decrease (P < 0.01) in the force generating capacity of individual fibres. The loss of fast MUs was partially compensated by activity-dependent fast-to-slower fibre type transitions, as determined by increases (P < 0.04) in the CSA and proportion of IIA fibres (from 4% to 14%) and IID/X fibres (from 31% to 39%), and decreases (P < 0.001) in the CSA and proportion of type IIB fibres (from 65% to 44%). We conclude that preferential loss of IIB fibres is incomplete at 60 days of age, and is consistent with a selective albeit gradual loss of FF MUs that is not fully compensated by sprouting of the remaining motoneurons that innervate type IIA or IID/X muscle fibres. Our findings indicate that disease progression in fast-twitch muscles of SOD1(G93A) mice involves parallel processes: (1) gradual selective motor axon die-back of the FF motor units that contain large type IIB muscle fibres, and of fatigue-intermediate motor units that innervate type IID/X muscle fibres, and (2) activity-dependent conversion of motor units to those innervated by smaller motor axons innervating type IIA fatigue-resistant muscle fibres.
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Affiliation(s)
- J Hegedus
- Centre for Neuroscience, 525 Heritage Medical Research Centre, Faculty of Medicine, University of Alberta, Edmonton, AB, Canada
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50
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Sawai S, Kanai K, Nakata M, Hiraga A, Misawa S, Isose S, Hattori T, Kuwabara S. Changes in excitability properties associated with axonal regeneration in human neuropathy and mouse Wallerian degeneration. Clin Neurophysiol 2008; 119:1097-105. [DOI: 10.1016/j.clinph.2008.01.022] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Revised: 01/15/2008] [Accepted: 01/25/2008] [Indexed: 10/22/2022]
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