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Yang Z, Marcoci C, Öztürk HK, Giama E, Yenicelik AG, Slanař O, Linington C, Desai R, Smith KJ. Tissue Hypoxia and Associated Innate Immune Factors in Experimental Autoimmune Optic Neuritis. Int J Mol Sci 2024; 25:3077. [PMID: 38474322 DOI: 10.3390/ijms25053077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2024] [Revised: 03/03/2024] [Accepted: 03/04/2024] [Indexed: 03/14/2024] Open
Abstract
Visual loss in acute optic neuritis is typically attributed to axonal conduction block due to inflammatory demyelination, but the mechanisms remain unclear. Recent research has highlighted tissue hypoxia as an important cause of neurological deficits and tissue damage in both multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE) and, here, we examine whether the optic nerves are hypoxic in experimental optic neuritis induced in Dark Agouti rats. At both the first and second peaks of disease expression, inflamed optic nerves labelled significantly for tissue hypoxia (namely, positive for hypoxia inducible factor-1α (HIF1α) and intravenously administered pimonidazole). Acutely inflamed nerves were also labelled significantly for innate markers of oxidative and nitrative stress and damage, including superoxide, nitric oxide and 3-nitrotyrosine. The density and diameter of capillaries were also increased. We conclude that in acute optic neuritis, the optic nerves are hypoxic and come under oxidative and nitrative stress and damage. Tissue hypoxia can cause mitochondrial failure and thus explains visual loss due to axonal conduction block. Tissue hypoxia can also induce a damaging oxidative and nitrative environment. The findings indicate that treatment to prevent tissue hypoxia in acute optic neuritis may help to restore vision and protect from damaging reactive oxygen and nitrogen species.
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Affiliation(s)
- Zhiyuan Yang
- Department of Neuroinflammation, UCL Queen Square Institute of Neurology, University College London, London WC1N 1PJ, UK
| | - Cristina Marcoci
- Department of Neuroinflammation, UCL Queen Square Institute of Neurology, University College London, London WC1N 1PJ, UK
| | - Hatice Kübra Öztürk
- Department of Neuroinflammation, UCL Queen Square Institute of Neurology, University College London, London WC1N 1PJ, UK
- Institute of Pharmacology, First Faculty of Medicine, Charles University and General University Hospital in Prague, 12800 Prague, Czech Republic
| | - Eleni Giama
- Department of Neuroinflammation, UCL Queen Square Institute of Neurology, University College London, London WC1N 1PJ, UK
| | - Ayse Gertrude Yenicelik
- Department of Neuroinflammation, UCL Queen Square Institute of Neurology, University College London, London WC1N 1PJ, UK
| | - Ondřej Slanař
- Institute of Pharmacology, First Faculty of Medicine, Charles University and General University Hospital in Prague, 12800 Prague, Czech Republic
| | - Christopher Linington
- School of Infection and Immunity, The Sir Graeme Davies Building, Glasgow G12 8TA, UK
| | - Roshni Desai
- Department of Neuroinflammation, UCL Queen Square Institute of Neurology, University College London, London WC1N 1PJ, UK
| | - Kenneth J Smith
- Department of Neuroinflammation, UCL Queen Square Institute of Neurology, University College London, London WC1N 1PJ, UK
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Buscho SE, Xia F, Shi S, Lin JL, Szczesny B, Zhang W, Motamedi M, Liu H. Non-Invasive Evaluation of Retinal Vascular Alterations in a Mouse Model of Optic Neuritis Using Laser Speckle Flowgraphy and Optical Coherence Tomography Angiography. Cells 2023; 12:2685. [PMID: 38067113 PMCID: PMC10705764 DOI: 10.3390/cells12232685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 11/04/2023] [Accepted: 11/20/2023] [Indexed: 12/18/2023] Open
Abstract
Optic neuritis, a characteristic feature of multiple sclerosis (MS), involves the inflammation of the optic nerve and the degeneration of retinal ganglion cells (RGCs). Although previous studies suggest that retinal blood flow alterations occur during optic neuritis, the precise location, the degree of impairment, and the underlying mechanisms remain unclear. In this study, we utilized two emerging non-invasive imaging techniques, laser speckle flowgraphy (LSFG) and optical coherence tomography angiography (OCTA), to investigate retinal vascular changes in a mouse model of MS, known as experimental autoimmune encephalomyelitis (EAE). We associated these changes with leukostasis, RGC injury, and the overall progression of EAE. LSFG imaging revealed a progressive reduction in retinal blood flow velocity and increased vascular resistance near the optic nerve head in the EAE model, indicating impaired ocular blood flow. OCTA imaging demonstrated significant decreases in vessel density, number of junctions, and total vessel length in the intermediate and deep capillary plexus of the EAE mice. Furthermore, our analysis of leukostasis revealed a significant increase in adherent leukocytes in the retinal vasculature of the EAE mice, suggesting the occurrence of vascular inflammation in the early development of EAE pathology. The abovechanges preceded or were accompanied by the characteristic hallmarks of optic neuritis, such as RGC loss and reduced visual acuity. Overall, our study sheds light on the intricate relationship between retinal vascular alterations and the progression of optic neuritis as well as MS clinical score. It also highlights the potential for the development of image-based biomarkers for the diagnosis and monitoring of optic neuritis as well as MS, particularly in response to emerging treatments.
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Affiliation(s)
- Seth E. Buscho
- Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch, Galveston, TX 77555, USA; (S.E.B.); (F.X.); (S.S.); (J.L.L.); (B.S.); (W.Z.); (M.M.)
| | - Fan Xia
- Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch, Galveston, TX 77555, USA; (S.E.B.); (F.X.); (S.S.); (J.L.L.); (B.S.); (W.Z.); (M.M.)
| | - Shuizhen Shi
- Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch, Galveston, TX 77555, USA; (S.E.B.); (F.X.); (S.S.); (J.L.L.); (B.S.); (W.Z.); (M.M.)
| | - Jonathan L. Lin
- Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch, Galveston, TX 77555, USA; (S.E.B.); (F.X.); (S.S.); (J.L.L.); (B.S.); (W.Z.); (M.M.)
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Bartosz Szczesny
- Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch, Galveston, TX 77555, USA; (S.E.B.); (F.X.); (S.S.); (J.L.L.); (B.S.); (W.Z.); (M.M.)
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Wenbo Zhang
- Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch, Galveston, TX 77555, USA; (S.E.B.); (F.X.); (S.S.); (J.L.L.); (B.S.); (W.Z.); (M.M.)
- Department of Neurobiology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Massoud Motamedi
- Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch, Galveston, TX 77555, USA; (S.E.B.); (F.X.); (S.S.); (J.L.L.); (B.S.); (W.Z.); (M.M.)
| | - Hua Liu
- Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch, Galveston, TX 77555, USA; (S.E.B.); (F.X.); (S.S.); (J.L.L.); (B.S.); (W.Z.); (M.M.)
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Cis-p-tau plays crucial role in lysolecithin-induced demyelination and subsequent axonopathy in mouse optic chiasm. Exp Neurol 2023; 359:114262. [PMID: 36343678 DOI: 10.1016/j.expneurol.2022.114262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 10/21/2022] [Accepted: 10/31/2022] [Indexed: 11/06/2022]
Abstract
Multiple sclerosis (MS) is an autoimmune demyelinating disease that leads to axon degeneration as the major cause of everlasting neurological disability. The cis-phosphorylated tau (cis-p-tau) is an isoform of tau phosphorylated on threonine 231 and causes tau fails to bind micro-tubules and promotes assembly. It gains toxic function and forms tangles in the cell which finally leads to cell death. An antibody raised against cis- p-tau (cis mAb) detects this isoform and induces its clearance. Here, we investigated the formation of cis-p-tau in a lysophosphatidylcholine (LPC)-induced prolonged demyelination model as well as the beneficial effects of its clearance using cis mAb. Cis -p-tau was increased in the lesion site, especially in axons and microglia. Behavioral and functional studies were performed using visual cliff test, visual placing test, and visual evoked potential recording. Cis-p-tau clearance resulted in decreased gliosis, protected myelin and reduced axon degeneration. Analysis of behavioral and electrophysiological data showed that clearance of cis-p-tau by cis mAb treatment improved the visual acuity along with the integrity of the optic pathway. Our results highlight the opportunity of using cis mAb as a new therapy for protecting myelin and axons in patients suffering from MS.
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Cojocaru A, Burada E, Bălșeanu AT, Deftu AF, Cătălin B, Popa-Wagner A, Osiac E. Roles of Microglial Ion Channel in Neurodegenerative Diseases. J Clin Med 2021; 10:jcm10061239. [PMID: 33802786 PMCID: PMC8002406 DOI: 10.3390/jcm10061239] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 03/02/2021] [Accepted: 03/11/2021] [Indexed: 12/15/2022] Open
Abstract
As the average age and life expectancy increases, the incidence of both acute and chronic central nervous system (CNS) pathologies will increase. Understanding mechanisms underlying neuroinflammation as the common feature of any neurodegenerative pathology, we can exploit the pharmacology of cell specific ion channels to improve the outcome of many CNS diseases. As the main cellular player of neuroinflammation, microglia play a central role in this process. Although microglia are considered non-excitable cells, they express a variety of ion channels under both physiological and pathological conditions that seem to be involved in a plethora of cellular processes. Here, we discuss the impact of modulating microglia voltage-gated, potential transient receptor, chloride and proton channels on microglial proliferation, migration, and phagocytosis in neurodegenerative diseases.
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Affiliation(s)
- Alexandru Cojocaru
- Department of Physiology, University of Medicine and Pharmacy of Craiova, 200349 Craiova, Romania; (A.C.); (E.B.); (A.-T.B.)
- Experimental Research Center for Normal and Pathological Aging, University of Medicine and Pharmacy of Craiova, 200349 Craiova, Romania
| | - Emilia Burada
- Department of Physiology, University of Medicine and Pharmacy of Craiova, 200349 Craiova, Romania; (A.C.); (E.B.); (A.-T.B.)
| | - Adrian-Tudor Bălșeanu
- Department of Physiology, University of Medicine and Pharmacy of Craiova, 200349 Craiova, Romania; (A.C.); (E.B.); (A.-T.B.)
- Experimental Research Center for Normal and Pathological Aging, University of Medicine and Pharmacy of Craiova, 200349 Craiova, Romania
| | - Alexandru-Florian Deftu
- Pain Center, Department of Anesthesiology, Lausanne University Hospital (CHUV), CH-1011 Lausanne, Switzerland;
- Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), CH-1011 Lausanne, Switzerland
| | - Bogdan Cătălin
- Department of Physiology, University of Medicine and Pharmacy of Craiova, 200349 Craiova, Romania; (A.C.); (E.B.); (A.-T.B.)
- Experimental Research Center for Normal and Pathological Aging, University of Medicine and Pharmacy of Craiova, 200349 Craiova, Romania
- Correspondence: (B.C.); (A.P.-W.)
| | - Aurel Popa-Wagner
- Chair of Vascular Neurology, Dementia and Ageing Research, University Hospital Essen, 45147 Essen, Germany
- Correspondence: (B.C.); (A.P.-W.)
| | - Eugen Osiac
- Department of Biophysics, University of Medicine and Pharmacy of Craiova, 200349 Craiova, Romania;
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Zhang Y, Li C, Huang L, Shen X, Zhao F, Wu C, Yan S. Relationship between Hyponatremia and Peripheral Neuropathy in Patients with Diabetes. J Diabetes Res 2021; 2021:9012887. [PMID: 34458375 PMCID: PMC8397566 DOI: 10.1155/2021/9012887] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/15/2021] [Accepted: 08/04/2021] [Indexed: 12/17/2022] Open
Abstract
OBJECTIVES Hyponatremia is a common complication of diabetes. However, the relationship between serum sodium level and diabetic peripheral neuropathy (DPN) is unknown. This study was aimed at investigating the relationship between low serum sodium level and DPN in Chinese patients with type 2 diabetes mellitus. METHODS A retrospective study was performed on 1928 patients with type 2 diabetes between 2010 and 2018. The multivariate test was used to analyze the relationship between the serum sodium level and the nerve conduction function. A restricted cubic spline was used to flexibly model and visualize the relationship between the serum sodium level and DPN, followed by logistic regression with adjustment. RESULTS As the serum sodium level increased, the prevalence of DPN had a reverse J-curve distribution with the serum sodium levels (69.6%, 53.7%, 49.6%, 43.9%, and 49.7%; P = 0.001). Significant differences existed between the serum sodium level and the motor nerve conduction velocity, sensory nerve conduction velocity, part of compound muscle action potential, and sensory nerve action potential of the participants. Compared with hyponatremia, the higher serum sodium level was a relative lower risk factor for DPN after adjusting for several potential confounders (OR = 0.430, 95%CI = 0.220-0.841; OR = 0.386, 95%CI = 0.198-0.755; OR = 0.297, 95%CI = 0.152-0.580; OR = 0.376, 95%CI = 0.190-0.743; all P < 0.05). Compared with low-normal serum sodium groups, the high-normal serum sodium level was also a risk factor for DPN (OR = 0.690, 95%CI = 0.526-0.905, P = 0.007). This relationship was particularly apparent in male participants, those aged <65 years, those with a duration of diabetes of <10 years, and those with a urinary albumin - to - creatinine ratio (UACR) < 30 mg/g. CONCLUSIONS Low serum sodium levels were independently associated with DPN, even within the normal range of the serum sodium. We should pay more attention to avoid the low serum sodium level in patients with type 2 diabetes mellitus.
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Affiliation(s)
- Yongze Zhang
- Department of Endocrinology, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Fujian Province Clinical Research Center for Metabolic Diseases, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Diabetes Research Institute of Fujian Province, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Metabolic Diseases Research Institute, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
| | - Chuanchuan Li
- Department of Endocrinology, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Fujian Province Clinical Research Center for Metabolic Diseases, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Diabetes Research Institute of Fujian Province, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Metabolic Diseases Research Institute, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
| | - Lingning Huang
- Department of Endocrinology, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Fujian Province Clinical Research Center for Metabolic Diseases, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Diabetes Research Institute of Fujian Province, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Metabolic Diseases Research Institute, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
| | - Ximei Shen
- Department of Endocrinology, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Fujian Province Clinical Research Center for Metabolic Diseases, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Diabetes Research Institute of Fujian Province, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Metabolic Diseases Research Institute, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
| | - Fengying Zhao
- Department of Endocrinology, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Fujian Province Clinical Research Center for Metabolic Diseases, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Diabetes Research Institute of Fujian Province, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Metabolic Diseases Research Institute, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
| | - Cailin Wu
- Department of Endocrinology, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Fujian Province Clinical Research Center for Metabolic Diseases, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Diabetes Research Institute of Fujian Province, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Metabolic Diseases Research Institute, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
| | - Sunjie Yan
- Department of Endocrinology, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Fujian Province Clinical Research Center for Metabolic Diseases, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Diabetes Research Institute of Fujian Province, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
- Metabolic Diseases Research Institute, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong Road, Fuzhou, Fujian 350005, China
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Uncini A, Santoro L. The electrophysiology of axonal neuropathies: More than just evidence of axonal loss. Clin Neurophysiol 2020; 131:2367-2374. [PMID: 32828039 DOI: 10.1016/j.clinph.2020.07.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 07/13/2020] [Accepted: 07/22/2020] [Indexed: 11/15/2022]
Abstract
It is common belief that axonal neuropathies are characterized by simple axonal degeneration and loss and that the electrophysiological correlates are just reduced compound muscle action potential and sensory nerve action potential amplitudes with normal or slightly slow conduction velocity. However, axonal autoimmune neuropathies with involvement of the nodal region and axonal neuropathies due to energy restriction such as occurring in nerve ischemia, thiamine deficiency, critical illness, and mitochondrial disorders present conduction failure that can be either reversible with prompt recovery or progress to axonal degeneration with poor outcome. Moreover autoimmune axonal neuropathies due to nodal voltage gated sodium channels dysfunction/disruption may show slowing of conduction velocity, even in the demyelinating range, possibly due to prolongation of the depolarization time required to reach the threshold for action potential regeneration at subsequent nodes. These observations widen the spectrum of the electrophysiological features in some axonal neuropathies, should be taken into account to avoid misdiagnoses and for correct prognostication, and should stimulate the quest of timely targeted treatments that can eventually halt the progression from conduction failure to axonal degeneration.
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Affiliation(s)
- Antonino Uncini
- Department of Neuroscience, Imaging and Clinical Sciences, University "G. d'Annunzio", 66100 Chieti-Pescara, Italy.
| | - Lucio Santoro
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University of Naples "Federico II", Naples, Italy
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Moldovan M, Pisciotta C, Pareyson D, Krarup C. Myelin protein zero gene dose dependent axonal ion-channel dysfunction in a family with Charcot-Marie-Tooth disease. Clin Neurophysiol 2020; 131:2440-2451. [PMID: 32829291 DOI: 10.1016/j.clinph.2020.06.034] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 05/29/2020] [Accepted: 06/28/2020] [Indexed: 11/28/2022]
Abstract
OBJECTIVE The myelin impairment in demyelinating Charcot-Marie-Tooth (CMT) disease leads to various degrees of axonal degeneration, the ultimate cause of disability. We aimed to assess the pathophysiological changes in axonal function related to the neuropathy severity in hypo-/demyelinating CMT patients associated with myelin protein zero gene (MPZ) deficiency. METHODS We investigated four family members (two parents and two sons) harboring a frameshift mutation (c.306delA, p.Asp104ThrfsTer14) in the MPZ gene, predicted to result in a nonfunctional P0, by conventional conduction studies and multiple measures of motor axon excitability. In addition to the conventional excitability studies of the median nerve at the wrist, we tested the spinal accessory nerves. Control measures were obtained from 14 healthy volunteers. RESULTS The heterozygous parents (aged 56 and 63) had a mild CMT1B whereas their two homozygous sons (aged 31 and 39 years) had a severe Dejerine-Sottas disease phenotype. The spinal accessory nerve excitability could be measured in all patients. The sons showed reduced deviations during depolarizing threshold electrotonus and other depolarizing features which were not apparent in the accessory and median nerve studies of the parents. Mathematical modeling indicated impairment in voltage-gated sodium channels. This interpretation was supported by comparative modeling of excitability measurements in MPZ deficient mice. CONCLUSION Our data suggest that axonal depolarization in the context of abnormal voltage-gated sodium channels precedes axonal degeneration in severely hypo-/demyelinating CMT as previously reported in the mouse models. SIGNIFICANCE Measures of the accessory nerve excitability could provide pathophysiological markers of neurotoxicity in severe demyelinating neuropathies.
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Affiliation(s)
- Mihai Moldovan
- Department of Neuroscience, University of Copenhagen, Denmark; Department of Clinical Neurophysiology, Rigshospitalet, Copenhagen, Denmark
| | - Chiara Pisciotta
- Unit of Rare Neurodegenerative and Neurometabolic Diseases, Department of Clinical Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Davide Pareyson
- Unit of Rare Neurodegenerative and Neurometabolic Diseases, Department of Clinical Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Christian Krarup
- Department of Neuroscience, University of Copenhagen, Denmark; Department of Clinical Neurophysiology, Rigshospitalet, Copenhagen, Denmark.
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Exercise-Induced Cognitive Improvement Is Associated with Sodium Channel-Mediated Excitability in APP/PS1 Mice. Neural Plast 2020; 2020:9132720. [PMID: 32256560 PMCID: PMC7103997 DOI: 10.1155/2020/9132720] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/16/2020] [Accepted: 02/19/2020] [Indexed: 12/19/2022] Open
Abstract
Elevated brain activation, or hyperexcitability, induces cognitive impairment and confers an increased risk of Alzheimer's disease (AD). Blocking the overexcitation of the neural network may be a promising new strategy to prevent, halt, and even reverse this condition. Physical exercise has been shown to be an effective cognitive enhancer that reduces the risk of AD in elderly individuals, but the underlying mechanisms are far from being fully understood. We explored whether long-term treadmill exercise attenuates amyloid precursor protein (APP)/presenilin-1 (PS1) mutation-induced aberrant network activity and thus improves cognition by altering the numbers and/or distribution of voltage-gated sodium channels (Nav) in transgenic mice. APP/PS1 mice aged 2, 3.5, 5, 6.5, 8, and 9 months underwent treadmill exercise with different durations or at different stages of AD. The alterations in memory, electroencephalogram (EEG) recordings, and expression levels and distributions of Nav functional members (Nav1.1α, Nav1.2, Nav1.6, and Navβ2) were evaluated. The results revealed that treadmill exercise with 12- and 24-week durations 1) induced significant improvement in novel object recognition (NOR) memory and Morris water maze (MWM) spatial memory; 2) partially reduced abnormal spike activity; and 3) redressed the disturbed cellular distribution of Nav1.1α, aberrant Navβ2 cleavage augmentation, and Nav1.6 upregulation. Additionally, APP/PS1 mice in the 24-week exercise group showed better performance in the NOR task and a large decrease in Nav1.6 expression, which was close to the wild-type level. This study suggests that exercise improves cognition and neural activity by altering the numbers and distribution of hippocampal Nav in APP/PS1 mice. Long-term treadmill exercise, for about 24 weeks, starting in the preclinical stage, is a promising therapeutic strategy for preventing AD and halting its progress.
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9
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The Na +/Ca 2+ exchangers in demyelinating diseases. Cell Calcium 2019; 85:102130. [PMID: 31812115 DOI: 10.1016/j.ceca.2019.102130] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 11/20/2019] [Indexed: 12/15/2022]
Abstract
Intracellular [Na+]i and [Ca2+]i imbalance significantly contribute to neuro-axonal dysfunctions and maladaptive myelin repair or remyelination failure in chronic inflammatory demyelinating diseases such as multiple sclerosis. Progress in recent years has led to significant advances in understanding how [Ca2+]i signaling network drive degeneration or remyelination of demyelinated axons. The Na+/Ca2+ exchangers (NCXs), a transmembrane protein family including three members encoded by ncx1, ncx2, and ncx3 genes, are emerging important regulators of [Na+]i and [Ca2+]i both in neurons and glial cells. Here we review recent advance highlighting the role of NCX exchangers in axons and myelin-forming cells, i.e. oligodendrocytes, which represent the major targets of the aberrant inflammatory attack in multiple sclerosis. The contribution of NCX subtypes to axonal pathology and myelin synthesis will be discussed. Although a definitive understanding of mechanisms regulating axonal pathology and remyelination failure in chronic demyelinating diseases is still lacking and requires further investigation, current knowledge suggest that NCX activity plays a crucial role in these processes. Defining the relative contributions of each NCX transporter in axon pathology and myelinating glia will constitute not only a major advance in understanding in detail the intricate mechanism of neurodegeneration and remyelination failure in demyelinating diseases but also will help to identify neuroprotective or remyelinating strategies targeting selective NCX exchangers as a means of treating MS.
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Hu T, Li SS, Lu MN, Zhang L, Chen B, Mao R, Mei R, Tan YX, Li S, Xiyang YB. Neuroprotection induced by Navβ2‑knockdown in APP/PS1 transgenic neurons is associated with NEP regulation. Mol Med Rep 2019; 20:2002-2011. [PMID: 31257483 DOI: 10.3892/mmr.2019.10406] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 05/29/2019] [Indexed: 11/06/2022] Open
Abstract
Voltage‑gated sodium channel β2 (Navβ2), as an unconventional substrate of β‑site amyloid precursor protein cleaving enzyme 1, is involved in regulating the neuronal surface expression of sodium channels. A previous study demonstrated that knockdown of Navβ2 protected neurons and induced spatial cognition improvement by partially reducing pathological amyloidogenic processing of amyloid precursor protein (APP) in aged APP/presenilin 1 (PS1) transgenic mice. The present study aimed to investigate whether Navβ2 knockdown altered APP metabolism via regulation of the Aβ‑degrading enzyme neprilysin (NEP). APPswe/PS1ΔE9 mice (APP/PS1 transgenic mice with a C57BL/6J genetic background) carrying a Navβ2‑knockdown mutation (APP/PS1/Navβ2‑kd) or without Navβ2 knockdown (APP/PS1) were used for cell culture and further analysis. The present results demonstrated that in APP/PS1 mouse‑derived neurons, Navβ2 knockdown partially reversed the reduction in pathological APP cleavage, and the recovery of neurite extension and neuron area. Additionally, Navβ2 knockdown increased NEP activity and levels, and the levels of intracellular domain fragment binding to the NEP promoter. The present findings suggested that knockdown of Navβ2 reversed the APP/PS1 mutation‑induced deficiency in amyloid β degradation by regulating NEP.
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Affiliation(s)
- Tao Hu
- Institute of Neuroscience, Basic Medical College, Kunming Medical University, Kunming, Yunnan 650500, P.R. China
| | - Shan-Shan Li
- Basic Medical College, Kunming Medical University, Kunming, Yunnan 650500, P.R. China
| | - Min-Nan Lu
- Experiment Center for Medical Science Research, Kunming Medical University, Kunming, Yunnan 650500, P.R. China
| | - Li Zhang
- Editorial Department of Journal of Kunming Medical University, Kunming, Yunnan 650500, P.R. China
| | - Bo Chen
- Experiment Center for Medical Science Research, Kunming Medical University, Kunming, Yunnan 650500, P.R. China
| | - Rui Mao
- School of Stomatology, Kunming Medical University, Kunming, Yunnan 650500, P.R. China
| | - Rong Mei
- Department of Neurology, The First People's Hospital of Yunnan Province, Kunming, Yunnan 650032, P.R. China
| | - Ya-Xin Tan
- Institute of Neuroscience, Basic Medical College, Kunming Medical University, Kunming, Yunnan 650500, P.R. China
| | - Shan Li
- Institute of Neuroscience, Basic Medical College, Kunming Medical University, Kunming, Yunnan 650500, P.R. China
| | - Yan-Bin Xiyang
- Institute of Neuroscience, Basic Medical College, Kunming Medical University, Kunming, Yunnan 650500, P.R. China
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11
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Kumar M, Varun CN, Dey G, Ravikumar R, Mahadevan A, Shankar SK, Prasad TSK. Identification of Host-Response in Cerebral Malaria Patients Using Quantitative Proteomic Analysis. Proteomics Clin Appl 2018; 12:e1600187. [PMID: 29389080 DOI: 10.1002/prca.201600187] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 10/08/2017] [Indexed: 12/15/2022]
Abstract
PURPOSE The objective of this study was to study the altered proteome in the frontal lobe of patients with CM. Unbiased analysis of differentially abundant proteins could lead to identification of host responses against Plasmodium falciparum infection, which will aid in better understanding of the molecular mechanism of pathophysiology in CM. EXPERIMENTAL DESIGN TMT-based quantitative proteomic analysis using high-resolution mass spectrometry is employed. In brief, proteins are isolated from frontal lobe samples, which are collected at autopsy from three cases of CM and three control subjects. Equal amounts of protein from each case are digested using trypsin and labeled with different TMT reagents. The pooled sample is fractionated using strong cation exchange chromatography and analyzed on Orbitrap Fusion in triplicates. For accurate quantitation of peptides, the samples are analyzed in MS3 mode. The data is searched against a combined database of human and P. falciparum proteins using Sequest and Mascot search engines. RESULTS A total of 4174 proteins are identified, of which, 107 are found to be differentially abundant in the test samples with significant p-value (<0.05). Proteins associated with biological processes such as innate immune response, complement system, coagulation, and platelet activation are found to be elevated in CM cases. In contrast, proteins associated with myelination, oxidative phosphorylation, regulation of reactive oxygen species, and sodium and calcium ions transport are found to be depleted in response to CM. In addition, three P. falciparum proteins exclusively in CM brain samples are also identified. CONCLUSIONS AND CLINICAL RELEVANCE The study signifies neuronal assault due to axonal injury, altered sodium and calcium ion channels, deregulated inflammation and demyelination as a part of host response to CM. Enhanced oxidative stress, repressed oxidative phosphorylation, and demyelination of axons may contribute to the severity of the disease. Further validation of these results on a large cohort can provide leads in the development of neuroprotective therapies for CM.
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Affiliation(s)
- Manish Kumar
- Institute of Bioinformatics, International Technology Park, Bangalore, India.,Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Chakrakodi N Varun
- Department of Neuromicrobiology, National Institute of Mental Health and Neuro Sciences, Bangalore, India
| | - Gourav Dey
- Institute of Bioinformatics, International Technology Park, Bangalore, India.,Manipal Academy of Higher Education, Manipal, Karnataka, India.,Center for Systems Biology and Molecular Medicine, Yenepoya (Deemed to be University), Mangalore, India
| | - Raju Ravikumar
- Department of Neuromicrobiology, National Institute of Mental Health and Neuro Sciences, Bangalore, India
| | - Anita Mahadevan
- Department of Neuropathology, National Institute of Mental Health and Neurosciences, Bangalore, India.,Human Brain Tissue Repository, Neurobiology Research Centre, National Institute of Mental Health and Neurosciences, Bangalore, India
| | - Susarla Krishna Shankar
- Department of Neuropathology, National Institute of Mental Health and Neurosciences, Bangalore, India.,Human Brain Tissue Repository, Neurobiology Research Centre, National Institute of Mental Health and Neurosciences, Bangalore, India
| | - T S Keshava Prasad
- Institute of Bioinformatics, International Technology Park, Bangalore, India.,Center for Systems Biology and Molecular Medicine, Yenepoya (Deemed to be University), Mangalore, India
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12
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Abstract
Increasing evidence suggests a key role for tissue energy failure in the pathophysiology of multiple sclerosis (MS). Studies in experimental autoimmune encephalomyelitis (EAE), a commonly used model of MS, have been instrumental in illuminating the mechanisms that may be involved in compromising energy production. In this article, we review recent advances in EAE research focussing on factors that conspire to impair tissue energy metabolism, such as tissue hypoxia, mitochondrial dysfunction, production of reactive oxygen/nitrogen species, and sodium dysregulation, which are directly affected by energy insufficiency, and promote cellular damage. A greater understanding of how inflammation affects tissue energy balance may lead to novel and effective therapeutic strategies that ultimately will benefit not only people affected by MS but also people affected by the wide range of other neurological disorders in which neuroinflammation plays an important role.
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Affiliation(s)
- Roshni A Desai
- Department of Neuroinflammation, UCL Institute of Neurology, London, UK
| | - Kenneth J Smith
- Department of Neuroinflammation, UCL Institute of Neurology, London, UK
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13
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Hu T, Xiao Z, Mao R, Chen B, Lu MN, Tong J, Mei R, Li SS, Xiao ZC, Zhang LF, Xiyang YB. Navβ2 knockdown improves cognition in APP/PS1 mice by partially inhibiting seizures and APP amyloid processing. Oncotarget 2017; 8:99284-99295. [PMID: 29245901 PMCID: PMC5725092 DOI: 10.18632/oncotarget.21849] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Accepted: 10/02/2017] [Indexed: 11/25/2022] Open
Abstract
Voltage-gated sodium channels beta 2 (Navβ2, encoded by SCN2B) is a substrate of β-site amyloid precursor protein cleaving enzyme 1 (BACE1) and regulates cell surface expression of channels in neurons. Previous studies reported enhanced Navβ2 processing by BACE1 in Alzheimer’s disease (AD) model and patients. We investigated whether changes in Navβ2 expression affect neuronal seizure and amyloid precursor protein (APP) processing in an AD mouse model. Our study used eight-month-old APP/presenilin 1 (PS1) mice and transgenic Navβ2 knockdown [by 61% vs. wild type (WT)] APP/PS1 mice (APP/PS1/Navβ2-kd), with age-matched WT and Navβ2 knockdown (Navβ2-kd) mice as controls. We found that Navβ2 knockdown in APP/PS1 mice partially reversed the abnormal Navβ2 cleavage and the changes in intracellular and total Nav1.1α expression. It also restored sodium currents density in hippocampal neurons and neuronal activity, as indicated by EEG tracing; improved Morris water maze performance; and shifted APP amyloidogenic metabolism towards non-amyloidogenic processing. There were no differences in these indicators between WT and Navβ2-kd mice. These results suggest Navβ2 knockdown may be a promising strategy for treating AD.
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Affiliation(s)
- Tao Hu
- Institute of Neuroscience, Basic Medical College, Kunming Medical University, Kunming, Yunnan, PR China.,Department of Laboratory Medicine, The Third People's Hospital of Yunnan Province, Kunming, Yunnan, PR China
| | - Zhangang Xiao
- Laboratory of Molecular Pharmacology, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan, PR China.,Key Laboratory of Medical Electrophysiology, Ministry of Education, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan, PR China
| | - Rui Mao
- School of Stomatology, Kunming Medical University, Kunming, Yunnan, PR China
| | - Bo Chen
- Experiment Center for Medical Science Research, Kunming Medical University, Kunming, Yunnan, PR China
| | - Min-Nan Lu
- Experiment Center for Medical Science Research, Kunming Medical University, Kunming, Yunnan, PR China
| | - Jun Tong
- Physical Education Department, Kunming Medical University, Kunming, Yunnan, PR China
| | - Rong Mei
- Department of Neurology, The First People's Hospital of Yunnan Province, Kunming, Yunnan, PR China
| | - Shan-Shan Li
- Basic Medical College, Kunming Medical University, Kunming, Yunnan, PR China
| | - Zhi-Cheng Xiao
- Institute of Molecular and Clinical Medicine, Kunming Medical University, Kunming, Yunnan, PR China.,Monash Immunology and Stem Cell Laboratories (MISCL), Monash University, Clayton, VIC, Australia
| | - Lian-Feng Zhang
- Key Laboratory of Human Diseases Comparative Medicine, Ministry of Health, Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences(CAMS) & Comparative Medicine Centre, Peking Union Medical College (PUMC), Beijing, China
| | - Yan-Bin Xiyang
- Institute of Neuroscience, Basic Medical College, Kunming Medical University, Kunming, Yunnan, PR China
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14
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Keppel Hesselink JM, Kopsky DJ. Phenytoin: neuroprotection or neurotoxicity? Neurol Sci 2017; 38:1137-1141. [PMID: 28497312 DOI: 10.1007/s10072-017-2993-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 05/03/2017] [Indexed: 11/29/2022]
Abstract
Phenytoin is an 80-year young molecule and new indications are still emerging. The neuroprotective potential of phenytoin has been evaluated for decades. Recently, a positive phase II trial supported its further development in the treatment of optic neuritis in multiple sclerosis. In 1942, however, peripheral neuritis was first reported to be an adverse event of phenytoin, and since then a small but steady stream of publications discussed peripheral polyneuropathy as being a possible adverse event of phenytoin. We have reviewed the literature and concluded there is some supportive evidence for a reversible polyneuropathy after the oral use of phenytoin, though with no evidence for clear neurotoxicity on the level of peripheral nerves. This is probably due to the fact that the pharmacological effects of phenytoin, based on the stabilizing effect of the voltage-gated sodium channels, make impairment of nerve conduction in asymptomatic and symptomatic reversible polyneuropathies plausible. Clear toxically-induced phenytoin-related polyneuropathies, however, are extremely rare and are always related to high dose or high plasma levels of phenytoin, mostly developing during many years of therapy. We could only find one case of a probable reversible chronic phenytoin intoxication resulting in a biopsy proven axonal atrophy with secondary demyelination and signs of remyelination. All case series and case reports published are insufficient in detail to prove a clear causal relation between phenytoin intake and the induction of a peripheral polyneuropathy. Phenytoin does not lead to irreversible toxicity of the peripheral nerves and might, on the other hand, have neuroprotective properties.
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Affiliation(s)
| | - David J Kopsky
- Institute for Neuropathic Pain, Vespuccistraat 64-III, 1056 SN, Amsterdam, The Netherlands.
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15
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Ayache SS, Chalah MA. Fatigue in multiple sclerosis – Insights into evaluation and management. Neurophysiol Clin 2017; 47:139-171. [DOI: 10.1016/j.neucli.2017.02.004] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 02/15/2017] [Indexed: 12/20/2022] Open
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16
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Lindsly C, Gonzalez-Islas C, Wenner P. Elevated intracellular Na + concentrations in developing spinal neurons. J Neurochem 2017; 140:755-765. [PMID: 28027400 DOI: 10.1111/jnc.13936] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Revised: 11/09/2016] [Accepted: 12/05/2016] [Indexed: 11/30/2022]
Abstract
Over 25 years ago it was first reported that intracellular chloride levels (Cl-in ) were higher in developing neurons than in maturity. This finding has had significant implications for understanding the excitability of developing networks and recognizing the underlying causes of hyperexcitability associated with disease and neural injury. While there is some evidence that intracellular sodium levels (Na+in ) change during the development of non-neural cells, it has largely been assumed that Na+in is the same in developing and mature neurons. Here, using the sodium indicator SBFI, we test this idea and find that Na+in is significantly higher in embryonic spinal motoneurons and interneurons than in maturity. We find that Na+in reaches ~ 60 mM in mid-embryonic development and is then reduced to ~ 30 mM in late embryonic development. By retrogradely labeling motoneurons with SBFI we can reliably follow Na+in levels in vitro for hours. Bursts of spiking activity, and blocking voltage-gated sodium channels did not influence observed motoneuron sodium levels. On the other hand, Na+in was reduced by blocking the Na+ -K+ -2Cl- cotransporter NKCC1, and was highly sensitive to changes in external Na+ and a blocker of the Na+ /K+ ATPase. Our findings suggest that the Na+ gradient is weaker in embryonic neuronal development and strengthens in maturity in a manner similar to that of Cl- .
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Affiliation(s)
- Casie Lindsly
- Physiology Department, Emory University, School of Medicine, Atlanta, Georgia, USA
| | - Carlos Gonzalez-Islas
- Physiology Department, Emory University, School of Medicine, Atlanta, Georgia, USA.,Doctorado en Ciencias Biológicas Universidad Autónoma de Tlaxcala, Tlaxcala, México
| | - Peter Wenner
- Physiology Department, Emory University, School of Medicine, Atlanta, Georgia, USA
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17
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An oral NaV1.8 blocker improves motor function in mice completely deficient of myelin protein P0. Neurosci Lett 2016; 632:33-8. [PMID: 27530546 DOI: 10.1016/j.neulet.2016.08.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 08/11/2016] [Accepted: 08/12/2016] [Indexed: 01/06/2023]
Abstract
Mice deficient of myelin protein P0 are established models of demyelinating Charcot-Marie-Tooth (CMT) disease. Dysmyelination in these mice is associated with an ectopic expression of the sensory neuron specific sodium channel isoform NaV1.8 on motor axons. We reported that in P0+/-, a model of CMT1B, the membrane dysfunction could be acutely improved by a novel oral NaV1.8 blocker referred to as Compound 31 (C31, Bioorg. Med. Chem. Lett. 2010, 20, 6812; AbbVie Inc.). The aim of this study was to investigate the extent to which C31 treatment could also improve the motor axon function in P0-/-, a CMT model with a much more severe neuropathy. We found that the progressive impairment of motor performance from 1 to 4 months of age in P0-/- could be acutely reversed by C31 treatment. The effect was associated with an improvement of the amplitude of the plantar CMAP evoked by tibial nerve stimulation. The corresponding motor nerve excitability studies by "threshold tracking" showed changes after C31 consistent with attenuation of a resting membrane depolarization. Our data suggest that the depolarizing motor conduction failure in P0-/- could be acutely improved by C31. This provides proof-of-concept that treatment with oral subtype-selective NaV1.8 blockers could be used to improve the motor function in severe forms of demyelinating CMT.
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18
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Rosberg MR, Alvarez S, Klein D, Nielsen FC, Martini R, Levinson SR, Krarup C, Moldovan M. Progression of motor axon dysfunction and ectopic Nav1.8 expression in a mouse model of Charcot-Marie-Tooth disease 1B. Neurobiol Dis 2016; 93:201-14. [PMID: 27215377 DOI: 10.1016/j.nbd.2016.05.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 05/11/2016] [Accepted: 05/18/2016] [Indexed: 12/13/2022] Open
Abstract
Mice heterozygously deficient for the myelin protein P0 gene (P0+/-) develop a slowly progressing neuropathy modeling demyelinating Charcot-Marie-Tooth disease (CMT1B). The aim of the study was to investigate the long-term progression of motor dysfunction in P0+/- mice at 3, 7, 12 and 20months. By comparison with WT littermates, P0+/- showed a decreasing motor performance with age. This was associated with a progressive reduction in amplitude and increase in latency of the plantar compound muscle action potential (CMAP) evoked by stimulation of the tibial nerve at ankle. This progressive functional impairment was in contrast to the mild demyelinating neuropathy of the tibial nerve revealed by histology. "Threshold-tracking" studies showed impaired motor axon excitability in P0+/- from 3months. With time, there was a progressive reduction in threshold deviations during both depolarizing and hyperpolarizing threshold electrotonus associated with increasing resting I/V slope and increasing strength-duration time constant. These depolarizing features in excitability in P0+/- as well as the reduced CMAP amplitude were absent in P0+/- NaV1.8 knockouts, and could be acutely reversed by selective pharmacologic block of NaV1.8 in P0+/-. Mathematical modeling indicated an association of altered passive cable properties with a depolarizing shift in resting membrane potential and increase in the persistent Na(+) current in P0+/-. Our data suggest that ectopic NaV1.8 expression precipitates depolarizing conduction failure in CMT1B, and that motor axon dysfunction in demyelinating neuropathy is pharmacologically reversible.
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Affiliation(s)
- Mette R Rosberg
- Institute of Neuroscience and Pharmacology, University of Copenhagen, Denmark; Department of Clinical Neurophysiology, The Neuroscience Center, Copenhagen University Hospital (Rigshospitalet), Denmark
| | - Susana Alvarez
- Institute of Neuroscience and Pharmacology, University of Copenhagen, Denmark; Department of Clinical Neurophysiology, The Neuroscience Center, Copenhagen University Hospital (Rigshospitalet), Denmark
| | - Dennis Klein
- Neurology, Developmental Neurobiology, University of Würzburg, Germany
| | | | - Rudolf Martini
- Neurology, Developmental Neurobiology, University of Würzburg, Germany
| | - S Rock Levinson
- University of Colorado, Denver, Physiology and Biophysics, United States
| | - Christian Krarup
- Institute of Neuroscience and Pharmacology, University of Copenhagen, Denmark; Department of Clinical Neurophysiology, The Neuroscience Center, Copenhagen University Hospital (Rigshospitalet), Denmark
| | - Mihai Moldovan
- Institute of Neuroscience and Pharmacology, University of Copenhagen, Denmark; Department of Clinical Neurophysiology, The Neuroscience Center, Copenhagen University Hospital (Rigshospitalet), Denmark
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19
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Moldovan M, Rosberg MR, Alvarez S, Klein D, Martini R, Krarup C. Aging-associated changes in motor axon voltage-gated Na + channel function in mice. Neurobiol Aging 2016; 39:128-39. [DOI: 10.1016/j.neurobiolaging.2015.12.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2014] [Revised: 12/13/2015] [Accepted: 12/14/2015] [Indexed: 01/17/2023]
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20
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Pappalardo LW, Black JA, Waxman SG. Sodium channels in astroglia and microglia. Glia 2016; 64:1628-45. [PMID: 26919466 DOI: 10.1002/glia.22967] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 12/27/2015] [Accepted: 01/04/2016] [Indexed: 12/19/2022]
Abstract
Voltage-gated sodium channels are required for electrogenesis in excitable cells. Their activation, triggered by membrane depolarization, generates transient sodium currents that initiate action potentials in neurons, cardiac, and skeletal muscle cells. Cells that have not traditionally been considered to be excitable (nonexcitable cells), including glial cells, also express sodium channels in physiological conditions as well as in pathological conditions. These channels contribute to multiple functional roles that are seemingly unrelated to the generation of action potentials. Here, we discuss the dynamics of sodium channel expression in astrocytes and microglia, and review evidence for noncanonical roles in effector functions of these cells including phagocytosis, migration, proliferation, ionic homeostasis, and secretion of chemokines/cytokines. We also examine possible mechanisms by which sodium channels contribute to the activity of glial cells, with an eye toward therapeutic implications for central nervous system disease. GLIA 2016;64:1628-1645.
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Affiliation(s)
- Laura W Pappalardo
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT
| | - Joel A Black
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT
| | - Stephen G Waxman
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT
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21
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Chalah MA, Riachi N, Ahdab R, Créange A, Lefaucheur JP, Ayache SS. Fatigue in Multiple Sclerosis: Neural Correlates and the Role of Non-Invasive Brain Stimulation. Front Cell Neurosci 2015; 9:460. [PMID: 26648845 PMCID: PMC4663273 DOI: 10.3389/fncel.2015.00460] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Accepted: 11/11/2015] [Indexed: 12/21/2022] Open
Abstract
Multiple sclerosis (MS) is a chronic progressive inflammatory disease of the central nervous system (CNS) and the major cause of non-traumatic disability in young adults. Fatigue is a frequent symptom reported by the majority of MS patients during their disease course and drastically affects their quality of life. Despite its significant prevalence and impact, the underlying pathophysiological mechanisms are not well elucidated. MS fatigue is still considered the result of multifactorial and complex constellations, and is commonly classified into “primary” fatigue related to the pathological changes of the disease itself, and “secondary” fatigue attributed to mimicking symptoms, comorbid sleep and mood disorders, and medications side effects. Radiological, physiological, and endocrine data have raised hypotheses regarding the origin of this symptom, some of which have succeeded in identifying an association between MS fatigue and structural or functional abnormalities within various brain networks. Hence, the aim of this work is to reappraise the neural correlates of MS fatigue and to discuss the rationale for the emergent use of noninvasive brain stimulation (NIBS) techniques as potential treatments. This will include a presentation of the various NIBS modalities and a suggestion of their potential mechanisms of action in this context. Specific issues related to the value of transcranial direct current stimulation (tDCS) will be addressed.
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Affiliation(s)
- Moussa A Chalah
- EA 4391, Excitabilité Nerveuse et Thérapeutique, Université Paris-Est-Créteil Créteil, France ; Service de Physiologie - Explorations Fonctionnelles, Hôpital Henri Mondor, Assistance Publique - Hôpitaux de Paris Créteil, France
| | - Naji Riachi
- Neurology Division, University Medical Center Rizk Hospital Beirut, Lebanon
| | - Rechdi Ahdab
- EA 4391, Excitabilité Nerveuse et Thérapeutique, Université Paris-Est-Créteil Créteil, France ; Neurology Division, University Medical Center Rizk Hospital Beirut, Lebanon
| | - Alain Créange
- EA 4391, Excitabilité Nerveuse et Thérapeutique, Université Paris-Est-Créteil Créteil, France ; Service de Neurologie, Hôpital Henri Mondor, Assistance Publique - Hôpitaux de Paris Créteil, France
| | - Jean-Pascal Lefaucheur
- EA 4391, Excitabilité Nerveuse et Thérapeutique, Université Paris-Est-Créteil Créteil, France ; Service de Physiologie - Explorations Fonctionnelles, Hôpital Henri Mondor, Assistance Publique - Hôpitaux de Paris Créteil, France
| | - Samar S Ayache
- EA 4391, Excitabilité Nerveuse et Thérapeutique, Université Paris-Est-Créteil Créteil, France ; Service de Physiologie - Explorations Fonctionnelles, Hôpital Henri Mondor, Assistance Publique - Hôpitaux de Paris Créteil, France
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22
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Moldovan M, Alvarez S, Rosberg MR, Krarup C. Persistent alterations in active and passive electrical membrane properties of regenerated nerve fibers of man and mice. Eur J Neurosci 2015; 43:388-403. [DOI: 10.1111/ejn.13047] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 07/31/2015] [Accepted: 08/13/2015] [Indexed: 12/12/2022]
Affiliation(s)
- Mihai Moldovan
- Department of Neuroscience and Pharmacology; University of Copenhagen; Copenhagen Denmark
- Department of Clinical Neurophysiology; NF3063 Rigshospitalet 9 Blegdamsvej 2100 Copenhagen Denmark
| | - Susana Alvarez
- Department of Neuroscience and Pharmacology; University of Copenhagen; Copenhagen Denmark
- Department of Clinical Neurophysiology; NF3063 Rigshospitalet 9 Blegdamsvej 2100 Copenhagen Denmark
| | - Mette R. Rosberg
- Department of Neuroscience and Pharmacology; University of Copenhagen; Copenhagen Denmark
- Department of Clinical Neurophysiology; NF3063 Rigshospitalet 9 Blegdamsvej 2100 Copenhagen Denmark
| | - Christian Krarup
- Department of Neuroscience and Pharmacology; University of Copenhagen; Copenhagen Denmark
- Department of Clinical Neurophysiology; NF3063 Rigshospitalet 9 Blegdamsvej 2100 Copenhagen Denmark
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23
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Sadeghian M, Mullali G, Pocock JM, Piers T, Roach A, Smith KJ. Neuroprotection by safinamide in the 6-hydroxydopamine model of Parkinson's disease. Neuropathol Appl Neurobiol 2015; 42:423-35. [PMID: 26300398 DOI: 10.1111/nan.12263] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 08/11/2015] [Indexed: 02/02/2023]
Abstract
AIMS Current therapies in Parkinson's disease mainly treat symptoms rather than provide effective neuroprotection. We examined the effects of safinamide (monoamine oxidase B and sodium channel blocker) on microglial activation and the degeneration of dopaminergic neurons in a rat model of PD in vivo, and on microglia in vitro. METHODS Rats received unilateral stereotaxic injection of 6-hydroxydopamine into the medial forebrain bundle on day 0: The contralateral side served as control. Safinamide or vehicle was delivered from days 0 or 1, for 7 days, via sub-cutaneous mini-pumps. RESULTS In vehicle-treated rats 6-hydroxydopamine caused a significant increase in the number of activated MHC-II(+) microglia compared with the contralateral side, and only 50% of the dopaminergic neurons survived in the ipsilateral SNc. In contrast, rats treated daily with safinamide 50 and 150 mg/ml (on day 0 or 1) exhibited a significantly reduced number of activated microglia (55% reduction at 150 mg/ml) and a significant protection of dopaminergic neurons (80% of neurons survived) (P < 0.001) compared with vehicle-treated controls. Rasagiline, a monoamine oxidase B inhibitor, and lamotrigine, a sodium channel blocking drug, also protected dopaminergic neurons, indicating that safinamide may act by either or both mechanisms. Safinamide also reduced the activation of microglial cells in response to lipopolysaccharide exposure in vitro. CONCLUSION Safinamide therapy suppresses microglial activation and protects dopaminergic neurons from degeneration in the 6-hydroxydopamine model of PD, suggesting that the drug not only treats symptoms but also provides neuroprotection.
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Affiliation(s)
- Mona Sadeghian
- Department of Neuroinflammation, Queen Square Multiple Sclerosis Centre, UCL Institute of Neurology, London, UK
| | - Gizem Mullali
- Department of Neuroinflammation, Queen Square Multiple Sclerosis Centre, UCL Institute of Neurology, London, UK
| | - Jennifer M Pocock
- Department of Neuroinflammation, Queen Square Multiple Sclerosis Centre, UCL Institute of Neurology, London, UK
| | - Thomas Piers
- Department of Neuroinflammation, Queen Square Multiple Sclerosis Centre, UCL Institute of Neurology, London, UK
| | - Arthur Roach
- Parkinson's UK, London, UK.,Chord. Therapeutics, Geneva, Switzerland
| | - Kenneth J Smith
- Department of Neuroinflammation, Queen Square Multiple Sclerosis Centre, UCL Institute of Neurology, London, UK
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24
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XiYang YB, Wang YC, Zhao Y, Ru J, Lu BT, Zhang YN, Wang NC, Hu WY, Liu J, Yang JW, Wang ZJ, Hao CG, Feng ZT, Xiao ZC, Dong W, Quan XZ, Zhang LF, Wang TH. Sodium Channel Voltage-Gated Beta 2 Plays a Vital Role in Brain Aging Associated with Synaptic Plasticity and Expression of COX5A and FGF-2. Mol Neurobiol 2015; 53:955-967. [PMID: 25575679 DOI: 10.1007/s12035-014-9048-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Accepted: 12/02/2014] [Indexed: 02/05/2023]
Abstract
The role of sodium channel voltage-gated beta 2 (SCN2B) in brain aging is largely unknown. The present study was therefore designed to determine the role of SCN2B in brain aging by using the senescence-accelerated mice prone 8 (SAMP8), a brain senescence-accelerated animal model, together with the SCN2B transgenic mice. The results showed that SAMP8 exhibited impaired learning and memory functions, assessed by the Morris water maze test, as early as 8 months of age. The messenger RNA (mRNA) and protein expressions of SCN2B were also upregulated in the prefrontal cortex at this age. Treatment with traditional Chinese anti-aging medicine Xueshuangtong (Panax notoginseng saponins, PNS) significantly reversed the SCN2B expressions in the prefrontal cortex, resulting in improved learning and memory. Moreover, SCN2B knockdown transgenic mice were generated and bred to determine the roles of SCN2B in brain senescence. A reduction in the SCN2B level by 60.68% resulted in improvement in the hippocampus-dependent spatial recognition memory and long-term potential (LTP) slope of field excitatory postsynaptic potential (fEPSP), followed by an upregulation of COX5A mRNA levels and downregulation of fibroblast growth factor-2 (FGF-2) mRNA expression. Together, the present findings indicated that SCN2B could play an important role in the aging-related cognitive deterioration, which is associated with the regulations of COX5A and FGF-2. These findings could provide the potential strategy of candidate target to develop antisenescence drugs for the treatment of brain aging.
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Affiliation(s)
- Yan-Bin XiYang
- Institute of Neuroscience, Kunming Medical University, 1168 West Chunrong Road, Yuhua Avenue, Chenggong District, Kunming, 650500, Yunnan, China.,Institute of Neurological Disease, State Key Lab of Biotherapy, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, China
| | - You-Cui Wang
- Institute of Neurological Disease, State Key Lab of Biotherapy, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, China
| | - Ya Zhao
- Institute of Neuroscience, Kunming Medical University, 1168 West Chunrong Road, Yuhua Avenue, Chenggong District, Kunming, 650500, Yunnan, China
| | - Jin Ru
- Institute of Neuroscience, Kunming Medical University, 1168 West Chunrong Road, Yuhua Avenue, Chenggong District, Kunming, 650500, Yunnan, China
| | - Bing-Tuan Lu
- Institute of Neuroscience, Kunming Medical University, 1168 West Chunrong Road, Yuhua Avenue, Chenggong District, Kunming, 650500, Yunnan, China.,Institute of Neurological Disease, State Key Lab of Biotherapy, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, China
| | - Yue-Ning Zhang
- Institute of Neuroscience, Kunming Medical University, 1168 West Chunrong Road, Yuhua Avenue, Chenggong District, Kunming, 650500, Yunnan, China
| | - Nai-Chao Wang
- Institute of Neuroscience, Kunming Medical University, 1168 West Chunrong Road, Yuhua Avenue, Chenggong District, Kunming, 650500, Yunnan, China
| | - Wei-Yan Hu
- Institute of Molecular and Clinical Medicine, Kunming Medical University, 1168 West Chunrong Road, Yuhua Avenue, Chenggong District, Kunming, 650500, Yunnan, China.,Monash Immunology and Stem Cell Laboratories (MISCL), Monash University, Clayton, VIC, Australia
| | - Jia Liu
- Institute of Neuroscience, Kunming Medical University, 1168 West Chunrong Road, Yuhua Avenue, Chenggong District, Kunming, 650500, Yunnan, China.,Institute of Neurological Disease, State Key Lab of Biotherapy, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, China
| | - Jin-Wei Yang
- Institute of Neuroscience, Kunming Medical University, 1168 West Chunrong Road, Yuhua Avenue, Chenggong District, Kunming, 650500, Yunnan, China
| | - Zhao-Jun Wang
- Institute of Neuroscience, Kunming Medical University, 1168 West Chunrong Road, Yuhua Avenue, Chenggong District, Kunming, 650500, Yunnan, China
| | - Chun-Guang Hao
- Institute of Neuroscience, Kunming Medical University, 1168 West Chunrong Road, Yuhua Avenue, Chenggong District, Kunming, 650500, Yunnan, China
| | - Zhong-Tang Feng
- Institute of Neuroscience, Kunming Medical University, 1168 West Chunrong Road, Yuhua Avenue, Chenggong District, Kunming, 650500, Yunnan, China.,Institute of Neurological Disease, State Key Lab of Biotherapy, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, China
| | - Zhi-Cheng Xiao
- Institute of Molecular and Clinical Medicine, Kunming Medical University, 1168 West Chunrong Road, Yuhua Avenue, Chenggong District, Kunming, 650500, Yunnan, China.,Monash Immunology and Stem Cell Laboratories (MISCL), Monash University, Clayton, VIC, Australia
| | - Wei Dong
- Key Laboratory of Human Diseases Comparative Medicine, Ministry of Health, Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences (CAMS), 100021, Beijing, China.,Comparative Medicine Centre, Peking Union Medical College (PUMC), 100021, Beijing, China
| | - Xiong-Zhi Quan
- Key Laboratory of Human Diseases Comparative Medicine, Ministry of Health, Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences (CAMS), 100021, Beijing, China.,Comparative Medicine Centre, Peking Union Medical College (PUMC), 100021, Beijing, China
| | - Lian-Feng Zhang
- Key Laboratory of Human Diseases Comparative Medicine, Ministry of Health, Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences (CAMS), 100021, Beijing, China. .,Comparative Medicine Centre, Peking Union Medical College (PUMC), 100021, Beijing, China.
| | - Ting-Hua Wang
- Institute of Neuroscience, Kunming Medical University, 1168 West Chunrong Road, Yuhua Avenue, Chenggong District, Kunming, 650500, Yunnan, China. .,Institute of Neurological Disease, State Key Lab of Biotherapy, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, China.
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25
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Minagar A. Multiple Sclerosis: An Overview of Clinical Features, Pathophysiology, Neuroimaging, and Treatment Options. ACTA ACUST UNITED AC 2014. [DOI: 10.4199/c00116ed1v01y201408isp055] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Abstract
PURPOSE OF REVIEW The predominant clinical disease course of multiple sclerosis starts with reversible episodes of neurological disability, which transforms into progressive neurological decline. This review provides insight into the pathological differences during relapsing and progressive phases of multiple sclerosis. RECENT FINDINGS The clinical course of multiple sclerosis is variable, and the disease can be classified into relapsing and progressive phases. Pathological studies have been successful in distinguishing between these two forms of the disease and correlate with the clinical findings in terms of cellular responses, the inflammatory environment, and the location of lesions. SUMMARY Available therapies for multiple sclerosis patients, while effective during the relapsing phase, have little benefit for progressive multiple sclerosis patients. Development of therapies to benefit progressive multiple sclerosis patients will require a better understanding of the pathogenesis of progressive multiple sclerosis. This review discusses and compares the pathological findings in relapsing and progressive multiple sclerosis patients.
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Affiliation(s)
- Ranjan Dutta
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
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27
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Levin MC, Douglas JN, Meyers L, Lee S, Shin Y, Gardner LA. Neurodegeneration in multiple sclerosis involves multiple pathogenic mechanisms. Degener Neurol Neuromuscul Dis 2014; 4:49-63. [PMID: 32669900 PMCID: PMC7337253 DOI: 10.2147/dnnd.s54391] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 03/06/2014] [Indexed: 12/18/2022] Open
Abstract
Multiple sclerosis (MS) is a complex autoimmune disease that impairs the central nervous system (CNS). The neurological disability and clinical course of the disease is highly variable and unpredictable from one patient to another. The cause of MS is still unknown, but it is thought to occur in genetically susceptible individuals who develop disease due to a nongenetic trigger, such as altered metabolism, a virus, or other environmental factors. MS patients develop progressive, irreversible, neurological disability associated with neuronal and axonal damage, collectively known as neurodegeneration. Neurodegeneration was traditionally considered as a secondary phenomenon to inflammation and demyelination. However, recent data indicate that neurodegeneration develops along with inflammation and demyelination. Thus, MS is increasingly recognized as a neurodegenerative disease triggered by an inflammatory attack of the CNS. While both inflammation and demyelination are well described and understood cellular processes, neurodegeneration might be defined by a diverse pool of any of the following: neuronal cell death, apoptosis, necrosis, and virtual hypoxia. In this review, we present multiple theories and supporting evidence that identify common biological processes that contribute to neurodegeneration in MS.
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Affiliation(s)
- Michael C Levin
- Veterans Administration Medical Center.,Department of Neuroscience, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Joshua N Douglas
- Veterans Administration Medical Center.,Department of Neuroscience, University of Tennessee Health Science Center, Memphis, TN, USA
| | | | - Sangmin Lee
- Veterans Administration Medical Center.,Department of Neurology
| | - Yoojin Shin
- Veterans Administration Medical Center.,Department of Neurology
| | - Lidia A Gardner
- Veterans Administration Medical Center.,Department of Neurology
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28
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Esen N, Serkin Z, Dore-Duffy P. Induction of vascular remodeling: A novel therapeutic approach in EAE. J Neurol Sci 2013; 333:88-92. [DOI: 10.1016/j.jns.2013.06.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 06/04/2013] [Accepted: 06/06/2013] [Indexed: 01/06/2023]
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29
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Abstract
Multiple sclerosis (MS) is a demyelinating disease of the central nervous system that is pathologically characterized by inflammatory demyelination and neurodegeneration. Axonal damage, along with neuronal loss, occurs from disease onset and may lead to progressive and permanent disability. In contrast with the inflammatory pathways, the molecular mechanisms leading to MS neurodegeneration remain largely elusive. With improved understanding of these mechanisms, new potential therapeutic targets for neuroprotection have emerged. We review the current understanding of neurodegenerative processes at play in MS and discuss potential outcome measures and targets for neuroprotection trials.
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Affiliation(s)
- Amir-Hadi Maghzi
- Multiple Sclerosis Center, Department of Neurology, University of California San Francisco (UCSF), 675 Nelson Rising Lane, 2nd floor, Room 221F, Box 3206, 94158, San Francisco, CA, USA,
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30
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Alvarez S, Moldovan M, Krarup C. Prolonged high frequency electrical stimulation is lethal to motor axons of mice heterozygously deficient for the myelin protein P0 gene. Exp Neurol 2013; 247:552-61. [DOI: 10.1016/j.expneurol.2013.02.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 02/09/2013] [Accepted: 02/13/2013] [Indexed: 10/27/2022]
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31
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Pérez-Medina C, Patel N, Robson M, Lythgoe MF, Årstad E. Synthesis and evaluation of a 125I-labeled iminodihydroquinoline-derived tracer for imaging of voltage-gated sodium channels. Bioorg Med Chem Lett 2013; 23:5170-3. [PMID: 23910595 PMCID: PMC3764405 DOI: 10.1016/j.bmcl.2013.07.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/10/2013] [Accepted: 07/11/2013] [Indexed: 12/04/2022]
Abstract
In vivo imaging of voltage-gated sodium channels (VGSCs) can potentially provide insights into the activation of neuronal pathways and aid the diagnosis of a number of neurological diseases. The iminodihydroquinoline WIN17317-3 is one of the most potent sodium channel blockers reported to date and binds with high affinity to VGSCs throughout the rat brain. We have synthesized a 125I-labeled analogue of WIN17317-3 and evaluated the potential of the tracer for imaging of VGSCs with SPECT. Automated patch clamp studies with CHO cells expressing the Nav1.2 isoform and displacement studies with [3H]BTX yielded comparable results for the non-radioactive iodinated iminodihydroquinoline and WIN17317-3. However, the 125I-labeled tracer was rapidly metabolized in vivo, and suffered from low brain uptake and high accumulation of radioactivity in the intestines. The results suggest that iminodihydroquinolines are poorly suited for tracer development.
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Affiliation(s)
- Carlos Pérez-Medina
- Department of Chemistry and Institute of Nuclear Medicine, UCL, 235 Euston Road (T-5), London NW1 2BU, United Kingdom
| | - Niral Patel
- Department of Chemistry and Institute of Nuclear Medicine, UCL, 235 Euston Road (T-5), London NW1 2BU, United Kingdom
- Centre for Advanced Biomedical Imaging, UCL, 72 Huntley Street, London WC1E 6BT, United Kingdom
| | - Mathew Robson
- UCL Cancer Institute, University College London, 72 Huntley Street, London WC1E 6BT, United Kingdom
| | - Mark F. Lythgoe
- Centre for Advanced Biomedical Imaging, UCL, 72 Huntley Street, London WC1E 6BT, United Kingdom
| | - Erik Årstad
- Department of Chemistry and Institute of Nuclear Medicine, UCL, 235 Euston Road (T-5), London NW1 2BU, United Kingdom
- Corresponding author. Tel./fax: +44 (0)02076792344.
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32
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Peripheral motor axons of SOD1G127X mutant mice are susceptible to activity-dependent degeneration. Neuroscience 2013; 241:239-49. [DOI: 10.1016/j.neuroscience.2013.03.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 02/11/2013] [Accepted: 03/06/2013] [Indexed: 12/12/2022]
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33
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Morsali D, Bechtold D, Lee W, Chauhdry S, Palchaudhuri U, Hassoon P, Snell DM, Malpass K, Piers T, Pocock J, Roach A, Smith KJ. Safinamide and flecainide protect axons and reduce microglial activation in models of multiple sclerosis. ACTA ACUST UNITED AC 2013; 136:1067-82. [PMID: 23518709 DOI: 10.1093/brain/awt041] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Axonal degeneration is a major cause of permanent disability in the inflammatory demyelinating disease multiple sclerosis, but no therapies are known to be effective in axonal protection. Sodium channel blocking agents can provide effective protection of axons in the white matter in experimental models of multiple sclerosis, but the mechanism of action (directly on axons or indirectly via immune modulation) remains uncertain. Here we have examined the efficacy of two sodium channel blocking agents to protect white matter axons in two forms of experimental autoimmune encephalomyelitis, a common model of multiple sclerosis. Safinamide is currently in phase III development for use in Parkinson's disease based on its inhibition of monoamine oxidase B, but the drug is also a potent state-dependent inhibitor of sodium channels. Safinamide provided significant protection against neurological deficit and axonal degeneration in experimental autoimmune encephalomyelitis, even when administration was delayed until after the onset of neurological deficit. Protection of axons was associated with a significant reduction in the activation of microglia/macrophages within the central nervous system. To clarify which property of safinamide was likely to be involved in the suppression of the innate immune cells, the action of safinamide on microglia/macrophages was compared with that of the classical sodium channel blocking agent, flecainide, which has no recognized monoamine oxidase B activity, and which has previously been shown to protect the white matter in experimental autoimmune encephalomyelitis. Flecainide was also potent in suppressing microglial activation in experimental autoimmune encephalomyelitis. To distinguish whether the suppression of microglia was an indirect consequence of the reduction in axonal damage, or possibly instrumental in the axonal protection, the action of safinamide was examined in separate experiments in vitro. In cultured primary rat microglial cells activated by lipopolysaccharide, safinamide potently suppressed microglial superoxide production and enhanced the production of the anti-oxidant glutathione. The findings show that safinamide is effective in protecting axons from degeneration in experimental autoimmune encephalomyelitis, and that this effect is likely to involve a direct effect on microglia that can result in a less activated phenotype. Together, this work highlights the potential of safinamide as an effective neuroprotective agent in multiple sclerosis, and implicates microglia in the protective mechanism.
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Affiliation(s)
- Damineh Morsali
- Department of Neuroinflammation, UCL Institute of Neurology, Queen Square, 1 Wakefield Street, London, WC1N 1PJ, UK.
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Neuroprotection for acute optic neuritis-Can it work? Mult Scler Relat Disord 2013; 2:307-11. [PMID: 25877841 DOI: 10.1016/j.msard.2013.02.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 01/25/2013] [Accepted: 02/01/2013] [Indexed: 11/22/2022]
Abstract
Optic neuritis is a common manifestation of MS and the acute inflammatory lesion in the optic nerve resembles demyelinating plaques elsewhere in the CNS. As with other MS relapses, treatment with corticosteroids has little or no impact on the extent to which vision eventually recovers after an attack of optic neuritis. Neuroaxonal loss is now recognised as a major cause of permanent disability. Imaging of the retinal nerve fibre layer with optical coherence tomography (OCT) and of the optic nerve with MRI both demonstrate significant volume loss which correlates with impaired visual function. The extent of axonal loss correlates with the magnitude of inflammation and there is robust evidence that excessive accumulation of sodium ions within axons in an inflammatory environment leads to axonal degeneration. Partial blockade of sodium channels protects against axonal loss and improves clinical outcome in experimental models of MS. The recent randomised placebo-controlled trial of lamotrigine in secondary progressive MS did not demonstrate a protective effect on brain atrophy, and indeed the opposite effect was observed during the first year of treatment. Despite this, there were some positive treatment signals. Specifically the rate of decline of walking speed was halved in the active group compared to placebo and the treatment compliant group had a significantly lower serum concentration of neurofilament. The limitiations in the design of the lamotrigine trial have been addressed in the ongoing trial of neuroprotection with phenytoin in acute optic neuritis. Specifically, treatment will be tested in an early inflammatory lesion and the readout will be timed beyond the lag in development of atrophy in the optic nerve and retina and after any treatment related volume changes have subsided. If the treatment is successful, this form of neuroprotection should improve the recovery from relapses in general, since the pathophysiology of optic neuritis resembles that of other MS relapses.
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Gao C, Huang L, Long Y, Zheng J, Yang J, Pu S, Xie L. Y-39983, a selective Rho-kinase inhibitor, attenuates experimental autoimmune encephalomyelitis via inhibition of demyelination. Neuroimmunomodulation 2013; 20:334-40. [PMID: 24008512 DOI: 10.1159/000353568] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 06/05/2013] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Rho-associated kinase (ROCK) is a serine/threonine kinase and a major downstream effector of the small GTP-binding protein, Rho. Rho-ROCK triggers an intracellular signaling cascade that controls actin cytoskeleton and is essential for cell motility and adhesion, neurite outgrowth and retraction. In chronic disabling disease, multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE), demyelination and axonal damage are the major pathological changes contributing to neurological disability. We investigated the protective effect of a specific ROCK inhibitor, Y-39983, on demyelination and axonal damage in chronic EAE. METHODS Western blotting for myelin proteins, electron microscopy and solochrome cyanine staining was performed to evaluate demyelination while neurofilament proteins and cytoskeletal proteins including β-actin and β-tubulin were used to determine axonal damage in a chronic mouse model of EAE treated with Y-39983. RESULTS Y-39983 significantly suppressed clinical symptoms of EAE and prevented its relapse while increasing the amount of myelin proteins. No significant changes in neurofilaments and cytoskeletal proteins were observed compared with control EAE mice. The inhibition of demyelination by Y-39983 was confirmed by solochrome cyanine staining and electron microscopy. To further study the effect of Y-39983 on demyelination in EAE, we tested three major ROCK substrates, including myosin light chain phosphorylation, LIMK2 and collapsin response mediator protein-2. The activity of these molecules was decreased in EAE animals treated with Y-39983. CONCLUSION The inhibitory effect of Y-39983 on demyelination is probably due to the inactivation of ROCK substrates, which are important for neurite outgrowth, growth cone collapse and demyelination of oligodendrocytes.
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Affiliation(s)
- Cong Gao
- Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and Ministry of Education of China, Institute of Neuroscience and Second Affiliated Hospital of Guangzhou Medical University, and Department of Neurology, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
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36
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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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37
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Marina N, Sajic M, Bull ND, Hyatt AJ, Berry D, Smith KJ, Martin KR. Lamotrigine monotherapy does not provide protection against the loss of optic nerve axons in a rat model of ocular hypertension. Exp Eye Res 2012; 104:1-6. [DOI: 10.1016/j.exer.2012.09.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Revised: 06/22/2012] [Accepted: 09/03/2012] [Indexed: 12/31/2022]
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Abstract
Multiple sclerosis (MS) is an inflammatory demyelinating disease that is considered by many people to have an autoimmune aetiology. In recent years, new data emerging from histopathology, imaging and other studies have expanded our understanding of the disease and may change the way in which it is treated. Conceptual shifts have included: first, an appreciation of the extent to which the neuron and its axon are affected in MS, and second, elucidation of how the neurobiology of axon-glial and, particularly, axon-myelin interaction may influence disease progression. In this article, we review advances in both areas, focusing on the molecular mechanisms underlying axonal loss in acute inflammation and in chronic demyelination, and discussing how the restoration of myelin sheaths via the regenerative process of remyelination might prevent axon degeneration. An understanding of these processes could lead to better strategies for the prevention and treatment of axonal loss, which will ultimately benefit patients with MS.
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39
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Hayton T, Furby J, Smith KJ, Altmann DR, Brenner R, Chataway J, Hunter K, Tozer DJ, Miller DH, Kapoor R. Longitudinal changes in magnetisation transfer ratio in secondary progressive multiple sclerosis: data from a randomised placebo controlled trial of lamotrigine. J Neurol 2011; 259:505-14. [PMID: 21904901 DOI: 10.1007/s00415-011-6212-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2011] [Revised: 07/28/2011] [Accepted: 08/02/2011] [Indexed: 10/17/2022]
Abstract
Sodium blockade with lamotrigine is neuroprotective in animal models of central nervous system demyelination. This study evaluated the effect of lamotrigine on magnetisation transfer ratio (MTR), a putative magnetic resonance imaging measure of intact brain tissue, in a group of subjects with secondary progressive multiple sclerosis (MS). In addition, the utility of MTR measures for detecting change in clinically relevant pathology was evaluated. One hundred seventeen people attending the National Hospital for Neurology and Neurosurgery or the Royal Free Hospital, London, UK, were recruited into a double-blind, parallel-group trial. Subjects were randomly assigned by minimisation to receive lamotrigine (target dose 400 mg/day) or placebo for 2 years. Treating and assessing physicians and patients were masked to treatment allocation. Results of the primary endpoint, central cerebral volume, have been published elsewhere. Significant differences between the verum and placebo arms were seen in only two measures [normal appearing grey matter (NAGM) p = 0.036 and lesion peak height (PH) p = 0.004], and in both cases there was a greater reduction in MTR in the verum arm. Significant correlations were found of change in MS functional composite with all MTR measures except lesion and normal appearing white matter (NAWM) PH. However, the change in MTR measures over 2 years were small, with only NAGM mean (p = 0.001), lesion peak location (p = 0.11) and mean (p < 0.0001) changing significantly from baseline. These data did not show that lamotrigine was neuroprotective. The clinical correlation of MTR measures was consistent, but the responsiveness to change was limited.
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Affiliation(s)
- T Hayton
- Department of Neuroinflammation, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK.
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40
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Xiao Y, Jackson JO, Liang S, Cummins TR. Common molecular determinants of tarantula huwentoxin-IV inhibition of Na+ channel voltage sensors in domains II and IV. J Biol Chem 2011; 286:27301-10. [PMID: 21659528 DOI: 10.1074/jbc.m111.246876] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The voltage sensors of domains II and IV of sodium channels are important determinants of activation and inactivation, respectively. Animal toxins that alter electrophysiological excitability of muscles and neurons often modify sodium channel activation by selectively interacting with domain II and inactivation by selectively interacting with domain IV. This suggests that there may be substantial differences between the toxin-binding sites in these two important domains. Here we explore the ability of the tarantula huwentoxin-IV (HWTX-IV) to inhibit the activity of the domain II and IV voltage sensors. HWTX-IV is specific for domain II, and we identify five residues in the S1-S2 (Glu-753) and S3-S4 (Glu-811, Leu-814, Asp-816, and Glu-818) regions of domain II that are crucial for inhibition of activation by HWTX-IV. These data indicate that a single residue in the S3-S4 linker (Glu-818 in hNav1.7) is crucial for allowing HWTX-IV to interact with the other key residues and trap the voltage sensor in the closed configuration. Mutagenesis analysis indicates that the five corresponding residues in domain IV are all critical for endowing HWTX-IV with the ability to inhibit fast inactivation. Our data suggest that the toxin-binding motif in domain II is conserved in domain IV. Increasing our understanding of the molecular determinants of toxin interactions with voltage-gated sodium channels may permit development of enhanced isoform-specific voltage-gating modifiers.
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Affiliation(s)
- Yucheng Xiao
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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41
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Moldovan M, Alvarez S, Pinchenko V, Klein D, Nielsen FC, Wood JN, Martini R, Krarup C. Na(v)1.8 channelopathy in mutant mice deficient for myelin protein zero is detrimental to motor axons. ACTA ACUST UNITED AC 2010; 134:585-601. [PMID: 21169333 DOI: 10.1093/brain/awq336] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Myelin protein zero mutations were found to produce Charcot-Marie-Tooth disease phenotypes with various degrees of myelin impairment and axonal loss, ranging from the mild 'demyelinating' adult form to severe and early onset forms. Protein zero deficient homozygous mice ( ) show a severe and progressive dysmyelinating neuropathy from birth with compromised myelin compaction, hypomyelination and distal axonal degeneration. A previous study using immunofluorescence showed that motor nerves deficient of myelin protein zero upregulate the Na(V)1.8 voltage gated sodium channel isoform, which is normally present only in restricted populations of sensory axons. The aim of this study was to investigate the function of motor axons in protein zero-deficient mice with particular emphasis on ectopic Na(V)1.8 voltage gated sodium channel. We combined 'threshold tracking' excitability studies with conventional nerve conduction studies, behavioural studies using rotor-rod measurements, and histological measures to assess membrane dysfunction and its progression in protein zero deficient homozygous mutants as compared with age-matched wild-type controls. The involvement of Na(V)1.8 was investigated by pharmacologic block using the subtype-selective Na(V)1.8 blocker A-803467 and chronically in Na(V)1.8 knock-outs. We found that in the context of dysmyelination, abnormal potassium ion currents and membrane depolarization, the ectopic Na(V)1.8 channels further impair the motor axon excitability in protein zero deficient homozygous mutants to an extent that precipitates conduction failure in severely affected axons. Our data suggest that a Na(V)1.8 channelopathy contributed to the poor motor function of protein zero deficient homozygous mutants, and that the conduction failure was associated with partially reversible reduction of the electrically evoked muscle response and of the clinical function as indicated by the partial recovery of function at rotor-rod measurements. As a consequence of these findings of partially reversible dysfunction, we propose that the Na(V)1.8 voltage gated sodium channel should be considered as a novel therapeutic target for Charcot-Marie-Tooth disease.
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Affiliation(s)
- Mihai Moldovan
- Institute of Neuroscience and Pharmacology, Panum, University of Copenhagen, Denmark
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Dutta R, Trapp BD. Mechanisms of neuronal dysfunction and degeneration in multiple sclerosis. Prog Neurobiol 2010; 93:1-12. [PMID: 20946934 DOI: 10.1016/j.pneurobio.2010.09.005] [Citation(s) in RCA: 318] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 09/14/2010] [Accepted: 09/30/2010] [Indexed: 01/18/2023]
Abstract
Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system. Due to its high prevalence, MS is the leading cause of non-traumatic neurological disability in young adults in the United States and Europe. The clinical disease course is variable and starts with reversible episodes of neurological disability in the third or fourth decade of life. This transforms into a disease of continuous and irreversible neurological decline by the sixth or seventh decade. Available therapies for MS patients have little benefit for patients who enter this irreversible phase of the disease. It is well established that irreversible loss of axons and neurons are the major cause of the irreversible and progressive neurological decline that most MS patients endure. This review discusses the etiology, mechanisms and progress made in determining the cause of axonal and neuronal loss in MS.
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Affiliation(s)
- Ranjan Dutta
- Department of Neurosciences/NC30, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
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Matsui M, Kumar-Roine S, Darius HT, Chinain M, Laurent D, Pauillac S. Pacific ciguatoxin 1B-induced modulation of inflammatory mediators in a murine macrophage cell line. Toxicon 2010; 56:776-84. [DOI: 10.1016/j.toxicon.2009.05.039] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2009] [Revised: 05/14/2009] [Accepted: 05/14/2009] [Indexed: 11/15/2022]
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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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Van der Walt A, Butzkueven H, Kolbe S, Marriott M, Alexandrou E, Gresle M, Egan G, Kilpatrick T. Neuroprotection in multiple sclerosis: a therapeutic challenge for the next decade. Pharmacol Ther 2010; 126:82-93. [PMID: 20122960 DOI: 10.1016/j.pharmthera.2010.01.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Accepted: 01/19/2010] [Indexed: 12/20/2022]
Abstract
Multiple sclerosis (MS) is the commonest cause of progressive neurological disability amongst young, Caucasian adults. MS is considered to be an auto-immune disease that results from an attack against myelin, the layer which surrounds axons. The pathophysiology of MS is complex, with both demyelination and axonal degeneration contributing to what is essentially an inflammatory neurodegenerative disease. Axonal loss is increasingly being accepted as the histopathological correlate of neurological disability. Currently, the underpinnings of neurodegeneration in MS, and how to promote neuroprotection are only partly understood. No established treatments that directly reduce nervous system damage or enhance its repair are currently available. Moreover, the ability of currently available immunomodulatory therapies used to treat MS, such as interferon-beta, to prevent long-term disability is uncertain. Results from short-term randomized-controlled trials suggest a partial benefit with regards to disability outcomes, but this is yet to be established in long-term studies. Novel neuroprotective agents have been identified in preclinical studies but their development is being hampered by the absence of appropriate clinical platforms to test them. In this article, we will discuss some of the principal therapeutic candidates that could provide neuroprotection in MS and emerging methodologies by which to test them.
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Affiliation(s)
- Anneke Van der Walt
- The Royal Melbourne Hospital, Grattan St. Parkville, Melbourne, Australia; Centre for Neuroscience, University of Melbourne, Australia.
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Vucic S, Burke D, Kiernan MC. Fatigue in multiple sclerosis: mechanisms and management. Clin Neurophysiol 2010; 121:809-17. [PMID: 20100665 DOI: 10.1016/j.clinph.2009.12.013] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2009] [Revised: 12/03/2009] [Accepted: 12/03/2009] [Indexed: 12/19/2022]
Abstract
Multiple sclerosis [MS] is a chronic immune-mediated disorder of the central nervous system [CNS]. Fatigue may be a debilitating symptom in MS patients, adversely impacting on their quality of life. Clinically, fatigue may manifest as exhaustion, lack of energy, increased somnolence, or worsening of MS symptoms. Activity and heat typically serve to exacerbate symptoms of fatigue. There is now strong evidence to suggest that fatigue results from reduced voluntary activation of muscles by means of central mechanisms. Given that axonal demyelination is a pathological hallmark of MS, activity-dependent conduction block [ADCB] has been proposed as a mechanism underlying fatigue in MS. This ADCB results from axonal membrane hyperpolarization, mediated by the Na(+)/K(+) electrogenic pump, with conduction failure precipitated in demyelinated axons with a reduced safety factor of impulse transmission. In addition, Na(+)/K(+) pump dysfunction, as reported in MS, may induce a depolarizing conduction block associated with inactivation of Na(+) channels. These processes may induce secondary effects including axonal degeneration triggered by raised levels of intracellular Ca(2+) through reverse operation of the Na(+)-Ca(2+) exchanger. Restoration of normal conduction in demyelinated axons with selective channel blockers improves fatigue and may yet prove useful as a neuroprotective strategy, in preventing secondary axonal degeneration and consequent functional impairment.
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Affiliation(s)
- Steve Vucic
- Department of Neurology, Westmead Hospital and Western Clinical School, University of Sydney, Sydney, NSW, Australia
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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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O'Malley HA, Shreiner AB, Chen GH, Huffnagle GB, Isom LL. Loss of Na+ channel beta2 subunits is neuroprotective in a mouse model of multiple sclerosis. Mol Cell Neurosci 2008; 40:143-55. [PMID: 19013247 DOI: 10.1016/j.mcn.2008.10.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Revised: 06/10/2008] [Accepted: 10/02/2008] [Indexed: 01/05/2023] Open
Abstract
Multiple sclerosis (MS) is a CNS disease that includes demyelination and axonal degeneration. Voltage-gated Na+ channels are abnormally expressed and distributed in MS and its animal model, Experimental Allergic Encephalomyelitis (EAE). Up-regulation of Na+ channels along demyelinated axons is proposed to lead to axonal loss in MS/EAE. We hypothesized that Na+ channel beta2 subunits (encoded by Scn2b) are involved in MS/EAE pathogenesis, as beta2 is responsible for regulating levels of channel cell surface expression in neurons. We induced non-relapsing EAE in Scn2b(+/+) and Scn2b(-/-) mice on the C57BL/6 background. Scn2b(-/-) mice display a dramatic reduction in EAE symptom severity and lethality as compared to wildtype, with significant decreases in axonal degeneration and axonal loss. Scn2b(-/-) mice show normal peripheral immune cell populations, T cell proliferation, cytokine release, and immune cell infiltration into the CNS in response to EAE, suggesting that Scn2b inactivation does not compromise immune function. Our data suggest that loss of beta2 is neuroprotective in EAE by prevention of Na+ channel up-regulation in response to demyelination.
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Affiliation(s)
- Heather A O'Malley
- Department of Pharmacology, Program in Cellular and Molecular Biology, University of Michigan, 1301 MSRB III, SPC 5632, 1150 W. Medical Center Dr., Ann Arbor, MI 48109, USA
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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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