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Stikvoort García DJL, Goedee HS, van Eijk RPA, van Schelven LJ, van den Berg LH, Sleutjes BTHM. Revisiting distinct nerve excitability patterns in patients with amyotrophic lateral sclerosis. Brain 2024; 147:2842-2853. [PMID: 38662766 DOI: 10.1093/brain/awae131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 03/29/2024] [Accepted: 04/08/2024] [Indexed: 08/02/2024] Open
Abstract
Amyotrophic lateral sclerosis is a devastating neurodegenerative disease, characterized by loss of central and peripheral motor neurons. Although the disease is clinically and genetically heterogeneous, axonal hyperexcitability is a commonly observed feature that has been suggested to reflect an early pathophysiological step linked to the neurodegenerative cascade. Therefore, it is important to clarify the mechanisms causing axonal hyperexcitability and how these relate to the clinical characteristics of patients. Measures derived directly from a nerve excitability recording are frequently used as study end points, although their biophysical basis is difficult to deduce. Mathematical models can aid in the interpretation but are reliable only when applied to group-averaged recordings. Consequently, model estimates of membrane properties cannot be compared with clinical characteristics or treatment effects in individual patients, posing a considerable limitation in heterogeneous diseases, such as amyotrophic lateral sclerosis. To address these challenges, we revisited nerve excitability using a new pattern analysis-based approach (principal component analysis). We evaluated disease-specific patterns of excitability changes and established their biophysical origins. Based on the observed patterns, we developed new compound measures of excitability that facilitate the implementation of this approach in clinical settings. We found that excitability changes in amyotrophic lateral sclerosis patients (n = 161, median disease duration = 11 months) were characterized by four unique patterns compared with controls (n = 50, age and sex matched). These four patterns were best explained by changes in resting membrane potential (modulated by Na+/K+ currents), slow potassium and sodium currents (modulated by their gating kinetics) and refractory properties of the nerve. Consequently, we were able to show that altered gating of slow potassium channels was associated with, and predictive of, the rate of progression of the disease on the amyotrophic lateral sclerosis functional rating scale. Based on these findings, we designed four composite measures that capture these properties to facilitate implementation outside this study. Our findings demonstrate that changes in nerve excitability in patients with amyotrophic lateral sclerosis are dominated by four distinct patterns, each with a distinct biophysical origin. Based on this new approach, we provide evidence that altered slow potassium-channel function might play a role in the rate of disease progression. The magnitudes of these patterns, quantified using a similar approach or our new composite measures, have potential as efficient measures to study membrane properties directly in amyotrophic lateral sclerosis patients, and thus aid prognostic stratification and trial design.
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Affiliation(s)
| | - H Stephan Goedee
- Department of Neurology, Brain Centre Utrecht, University Medical Centre Utrecht, Utrecht, 3584CX, The Netherlands
| | - Ruben P A van Eijk
- Department of Neurology, Brain Centre Utrecht, University Medical Centre Utrecht, Utrecht, 3584CX, The Netherlands
- Biostatistics and Research Support, Julius Centre for Health Sciences and Primary Care, University Medical Centre Utrecht, Universiteitsweg 100, 3584CX, Utrecht, The Netherlands
| | - Leonard J van Schelven
- Department of Medical Technology and Clinical Physics, University Medical Centre Utrecht, 3584CX, Utrecht, The Netherlands
| | - Leonard H van den Berg
- Department of Neurology, Brain Centre Utrecht, University Medical Centre Utrecht, Utrecht, 3584CX, The Netherlands
| | - Boudewijn T H M Sleutjes
- Department of Neurology, Brain Centre Utrecht, University Medical Centre Utrecht, Utrecht, 3584CX, The Netherlands
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Zhong Y, Zhang X, Yang Q, Wang Q. Hepatorenal Toxicity after 7-Day Oral Administration of Low-Dose Tetrodotoxin and Its Distribution in the Main Tissues in Mice. Toxins (Basel) 2023; 15:564. [PMID: 37755990 PMCID: PMC10538156 DOI: 10.3390/toxins15090564] [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: 07/24/2023] [Revised: 08/31/2023] [Accepted: 09/07/2023] [Indexed: 09/28/2023] Open
Abstract
Tetrodotoxin (TTX) is a highly toxic compound detected in various edible marine animals even in European waters. To characterize the hazard by oral exposure to TTX, its tissue distribution was evaluated after single (75 μg/kg) or 7-day (25-125 μg/kg) oral administration in mice. Moreover, TTX liver and renal toxicity was evaluated after 7-day oral administration. The elimination cycle of a single oral dose of TTX (75 µg/kg) was found to be approximately 168 h (7 days). Daily oral administration of TTX at doses of 25, 75, and 125 µg/kg for 7 consecutive days revealed dose-dependent toxic effects on the liver and kidney. Histopathological examination showed increased inflammatory cell infiltration in the liver and kidney with higher TTX doses, along with disorganization of the hepatic cord and renal tubular cell arrangement. The study results indicated that TTX had more hepatotoxicity than nephrotoxicity in mice. These findings provide insights into the unintentional ingestion of a low dose of TTX in mammals, including humans, and emphasize the importance of food safety.
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Affiliation(s)
- Yaqian Zhong
- School of Food and Pharmacy, Zhejiang Ocean University, Zhoushan 316022, China; (Y.Z.); (Q.Y.); (Q.W.)
- Laboratory of Aquatic Product Processing and Quality Safety, Zhejiang Marine Fisheries Research Institute, Zhoushan 316100, China
| | - Xiaojun Zhang
- Laboratory of Aquatic Product Processing and Quality Safety, Zhejiang Marine Fisheries Research Institute, Zhoushan 316100, China
| | - Qiyu Yang
- School of Food and Pharmacy, Zhejiang Ocean University, Zhoushan 316022, China; (Y.Z.); (Q.Y.); (Q.W.)
- Laboratory of Aquatic Product Processing and Quality Safety, Zhejiang Marine Fisheries Research Institute, Zhoushan 316100, China
| | - Qianfeng Wang
- School of Food and Pharmacy, Zhejiang Ocean University, Zhoushan 316022, China; (Y.Z.); (Q.Y.); (Q.W.)
- Laboratory of Aquatic Product Processing and Quality Safety, Zhejiang Marine Fisheries Research Institute, Zhoushan 316100, China
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Ros LAA, Goedee HS, Franssen H, Asselman FL, Bartels B, Cuppen I, van Eijk RPA, Sleutjes BTHM, van der Pol WL, Wadman RI. Longitudinal prospective cohort study to assess peripheral motor function with extensive electrophysiological techniques in patients with Spinal Muscular Atrophy (SMA): the SMA Motor Map protocol. BMC Neurol 2023; 23:164. [PMID: 37095427 PMCID: PMC10124000 DOI: 10.1186/s12883-023-03207-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 04/14/2023] [Indexed: 04/26/2023] Open
Abstract
BACKGROUND Hereditary spinal muscular atrophy (SMA) is a motor neuron disorder with a wide range in severity in children and adults. Two therapies that alter splicing of the Survival Motor Neuron 2 (SMN2) gene, i.e. nusinersen and risdiplam, improve motor function in SMA, but treatment effects vary. Experimental studies indicate that motor unit dysfunction encompasses multiple features, including abnormal function of the motor neuron, axon, neuromuscular junction and muscle fibres. The relative contributions of dysfunction of different parts of the motor unit to the clinical phenotype are unknown. Predictive biomarkers for clinical efficacy are currently lacking. The goals of this project are to study the association of electrophysiological abnormalities of the peripheral motor system in relation to 1) SMA clinical phenotypes and 2) treatment response in patients treated with SMN2-splicing modifiers (nusinersen or risdiplam). METHODS We designed an investigator-initiated, monocentre, longitudinal cohort study using electrophysiological techniques ('the SMA Motor Map') in Dutch children (≥ 12 years) and adults with SMA types 1-4. The protocol includes the compound muscle action potential scan, nerve excitability testing and repetitive nerve stimulation test, executed unilaterally at the median nerve. Part one cross-sectionally assesses the association of electrophysiological abnormalities in relation to SMA clinical phenotypes in treatment-naïve patients. Part two investigates the predictive value of electrophysiological changes at two-months treatment for a positive clinical motor response after one-year treatment with SMN2-splicing modifiers. We will include 100 patients in each part of the study. DISCUSSION This study will provide important information on the pathophysiology of the peripheral motor system of treatment-naïve patients with SMA through electrophysiological techniques. More importantly, the longitudinal analysis in patients on SMN2-splicing modifying therapies (i.e. nusinersen and risdiplam) intents to develop non-invasive electrophysiological biomarkers for treatment response in order to improve (individualized) treatment decisions. TRIAL REGISTRATION NL72562.041.20 (registered at https://www.toetsingonline.nl . 26-03-2020).
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Affiliation(s)
- Leandra A A Ros
- Department of Neurology & Neurosurgery, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Heidelberglaan 100, 3508 GA, Utrecht, The Netherlands
| | - H Stephan Goedee
- Department of Neurology & Neurosurgery, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Heidelberglaan 100, 3508 GA, Utrecht, The Netherlands
| | - Hessel Franssen
- Department of Neurology & Neurosurgery, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Heidelberglaan 100, 3508 GA, Utrecht, The Netherlands
| | - Fay-Lynn Asselman
- Department of Neurology & Neurosurgery, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Heidelberglaan 100, 3508 GA, Utrecht, The Netherlands
| | - Bart Bartels
- Child Development and Exercise Centre, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Inge Cuppen
- Department of Neurology & Neurosurgery, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Heidelberglaan 100, 3508 GA, Utrecht, The Netherlands
| | - Ruben P A van Eijk
- Department of Neurology & Neurosurgery, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Heidelberglaan 100, 3508 GA, Utrecht, The Netherlands
- Biostatistics and Research Support, Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Boudewijn T H M Sleutjes
- Department of Neurology & Neurosurgery, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Heidelberglaan 100, 3508 GA, Utrecht, The Netherlands
| | - W Ludo van der Pol
- Department of Neurology & Neurosurgery, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Heidelberglaan 100, 3508 GA, Utrecht, The Netherlands
| | - Renske I Wadman
- Department of Neurology & Neurosurgery, University Medical Center Utrecht, UMC Utrecht Brain Center, Utrecht University, Heidelberglaan 100, 3508 GA, Utrecht, The Netherlands.
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Al Dhuhaibat ZK, Zarzour T. Tetrodotoxin Poisoning Due to Pufferfish Ingestion in the United Arab Emirates. Cureus 2023; 15:e33627. [PMID: 36788846 PMCID: PMC9911934 DOI: 10.7759/cureus.33627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/10/2023] [Indexed: 01/13/2023] Open
Abstract
Tetrodotoxin is a potent neurotoxin that is found in the ovaries and liver of pufferfish. This lethal toxin is heat stable and does not destroy by cooking that is why precaution should be taken when eating pufferfish. A 60-year-old male presented to the ED after eating pufferfish complaining of perioral and hand numbness, gait disturbance, and generalized body weakness. This presentation is due to a tetrodotoxin found in and not limited to the pufferfish he ingested. Despite having pufferfish with his family, he was the sole person to have symptoms because, unlike the other family members, he ate from the liver part of the fish. The patient was admitted for observation, received supportive care, and underwent multiple investigations that most came to be normal. He improved gradually and was discharged after staying for three nights in the hospital. Symptoms after eating the toxic parts of a pufferfish may progress to paralysis, and respiratory failure, and may lead to death. It is not common to have such fish eaten in the United Arab Emirates due to its limited availability.
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Affiliation(s)
| | - Talal Zarzour
- Emergency Medicine, National Health Service, London, GBR
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Klein RM, Layton ME, Regan H, Regan CP, Li Y, Filzen T, Cato M, Clements MK, Wang J, Sanoja R, Greshock TJ, Roecker AJ, Pero JE, Kim R, Burgey C, John CT, Wang YH, Bhandari N, Struyk A, Kraus RL, Henze DA, Houghton AK. Association of respiratory failure with inhibition of NaV1.6 in the phrenic nerve. Channels (Austin) 2022; 16:230-243. [PMID: 36239534 PMCID: PMC9578445 DOI: 10.1080/19336950.2022.2122309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
As part of a drug discovery effort to identify potent inhibitors of NaV1.7 for the treatment of pain, we observed that inhibitors produced unexpected cardiovascular and respiratory effects in vivo. Specifically, inhibitors administered to rodents produced changes in cardiovascular parameters and respiratory cessation. We sought to determine the mechanism of the in vivo adverse effects by studying the selectivity of the compounds on NaV1.5, NaV1.4, and NaV1.6 in in vitro and ex vivo assays. Inhibitors lacking sufficient NaV1.7 selectivity over NaV1.6 were associated with respiratory cessation after in vivo administration to rodents. Effects on respiratory rate in rats were consistent with effects in an ex vivo hemisected rat diaphragm model and in vitro NaV1.6 potency. Furthermore, direct blockade of the phrenic nerve signaling was observed at exposures known to cause respiratory cessation in rats. Collectively, these results support a significant role for NaV1.6 in phrenic nerve signaling and respiratory function.
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Affiliation(s)
- Rebecca M. Klein
- Merck Research Laboratories, Merck & Co., Rahway, NJ, USA,CONTACT Rebecca M. Klein 770 Sumneytown Pike, P.O. Box 4, West Point, PA19486, USA
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Ruijs TQ, Koopmans IW, de Kam ML, van Esdonk MJ, Koltzenburg M, Groeneveld GJ, Heuberger JA. Effects of Mexiletine and Lacosamide on Nerve Excitability in Healthy Subjects: A Randomized, Double-Blind, Placebo-Controlled, Crossover Study. Clin Pharmacol Ther 2022; 112:1008-1019. [PMID: 35762293 PMCID: PMC9795956 DOI: 10.1002/cpt.2694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 06/12/2022] [Indexed: 01/01/2023]
Abstract
Selective voltage-gated sodium channel blockers are of growing interest as treatment for pain. For drug development of such compounds, it would be critical to have a biomarker that can be used for proof-of-mechanism. We aimed to evaluate whether drug-induced changes in sodium conductance can be detected in the peripheral nerve excitability profile in 18 healthy subjects. In a randomized, double-blind, 3-way crossover study, effects of single oral doses of 333 mg mexiletine and 300 mg lacosamide were compared with placebo. On each study visit, motor and sensory nerve excitability measurements of the median nerve were performed (predose; and 3 and 6 hours postdose) using Qtrac. Treatment effects were calculated using an analysis of covariance (ANCOVA) with baseline as covariate. Mexiletine and lacosamide had significant effects on multiple motor and sensory nerve excitability variables. Depolarizing threshold electrotonus (TEd40 (40-60 ms)) decreased by mexiletine (estimated difference (ED) -1.37% (95% confidence interval (CI): -2.20, -0.547; P = 0.002) and lacosamide (ED -1.27%, 95% CI: -2.10, -0.443; P = 0.004) in motor nerves. Moreover, mexiletine and lacosamide decreased superexcitability (less negative) in motor nerves (ED 1.74%, 95% CI: 0.615, 2.87; P = 0.004, and ED 1.47%, 95% CI: 0.341, 2.60; P = 0.013, respectively). Strength-duration time constant decreased after lacosamide in motor- (ED -0.0342 ms, 95% CI: -0.0571, -0.0112; P = 0.005) and sensory nerves (ED -0.0778 ms, 95% CI: -0.116, -0.0399; P < 0.001). Mexiletine and lacosamide significantly decrease excitability of motor and sensory nerves, in line with their suggested mechanism of action. Results of this study indicate that nerve excitability threshold tracking can be an effective pharmacodynamic biomarker. The method could be a valuable tool in clinical drug development.
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Affiliation(s)
- Titia Q. Ruijs
- Centre for Human Drug ResearchLeidenThe Netherlands,Leiden University Medical CentreLeidenThe Netherlands
| | - Ingrid W. Koopmans
- Centre for Human Drug ResearchLeidenThe Netherlands,Leiden University Medical CentreLeidenThe Netherlands
| | | | | | | | - Geert Jan Groeneveld
- Centre for Human Drug ResearchLeidenThe Netherlands,Leiden University Medical CentreLeidenThe Netherlands
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Kang KR, Kim CY, Kim J, Ryu B, Lee SG, Baek J, Kim YJ, Lee JM, Lee Y, Choi SO, Woo DH, Park IH, Chung HM. Establishment of Neurotoxicity Assessment Using Microelectrode Array (MEA) with hiPSC-Derived Neurons and Evaluation of New Psychoactive Substances (NPS). Int J Stem Cells 2022; 15:258-269. [PMID: 35769054 PMCID: PMC9396014 DOI: 10.15283/ijsc21217] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 04/01/2022] [Accepted: 04/01/2022] [Indexed: 11/09/2022] Open
Abstract
Background and Objectives Currently, safety pharmacological tests for the central nervous system depend on animal behavioral analysis. However, due to the subjectivity of behavioral analysis and differences between species, there is a limit to appropriate nervous system toxicity assessment, therefore a new neurotoxicity assessment that can simulate the human central nervous system is required. Methods and Results In our study, we developed an in vitro neurotoxicity assessment focusing on neuronal function. To minimize the differences between species and fast screening, hiPSC-derived neurons and a microelectrode array (MEA) that could simultaneously measure the action potentials of the neuronal networks were used. After analyzing the molecular and electrophysiological characters of our neuronal network, we conducted a neurotoxicity assessment on neurotransmitters, neurotoxicants, illicit drugs, and new psychoactive substances (NPS). We found that most substances used in our experiments responded more sensitively to our MEA-based neurotoxicity assessment than to the conventional neurotoxicity assessment. Also, this is the first paper that evaluates various illicit drugs and NPS using MEA-based neurotoxicity assessment using hiPSC-derived neurons. Conclusions Our study expanded the scope of application of neurotoxicity assessment using hiPSC-derived neurons to NPS, and accumulated evaluation data of various toxic substances for hiPSC-derived neurons.
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Affiliation(s)
- Kyu-Ree Kang
- Department of Stem Cell Biology, School of Medicine, Konkuk University, Seoul, Korea
| | - C-Yoon Kim
- Department of Stem Cell Biology, School of Medicine, Konkuk University, Seoul, Korea.,Department of Physiology, College of Veterinary Medicine, Konkuk University, Seoul, Korea
| | - Jin Kim
- Department of Laboratory Animal Medicine, College of Veterinary Medicine, Seoul National University, Seoul, Korea
| | - Bokyeong Ryu
- Department of Laboratory Animal Medicine, College of Veterinary Medicine, Seoul National University, Seoul, Korea
| | - Seul-Gi Lee
- Department of Stem Cell Biology, School of Medicine, Konkuk University, Seoul, Korea
| | - Jieun Baek
- Department of Stem Cell Biology, School of Medicine, Konkuk University, Seoul, Korea
| | - Ye-Ji Kim
- Drug Abuse Research Group, Research Center of Convergence Toxicology, Korea Institute of Toxicology, Daejeon, Korea
| | - Jin-Moo Lee
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Cheongju, Korea
| | - Yootmo Lee
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Cheongju, Korea
| | - Sun-Ok Choi
- Pharmacological Research Division, Toxicological Evaluation and Research Department, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Cheongju, Korea
| | - Dong Ho Woo
- Drug Abuse Research Group, Research Center of Convergence Toxicology, Korea Institute of Toxicology, Daejeon, Korea
| | - Il Hwan Park
- Departments of Thoracis and Cardiovascular Surgery, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - Hyung Min Chung
- Department of Stem Cell Biology, School of Medicine, Konkuk University, Seoul, Korea
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Carroll AS, Howells J, Lin CS, Park SB, Simon N, Reilly MM, Vucic S, Kiernan MC. Differences in nerve excitability properties across upper limb sensory and motor axons. Clin Neurophysiol 2021; 136:138-149. [DOI: 10.1016/j.clinph.2021.12.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 11/16/2021] [Accepted: 12/07/2021] [Indexed: 11/24/2022]
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Bucciarelli GM, Lechner M, Fontes A, Kats LB, Eisthen HL, Shaffer HB. From Poison to Promise: The Evolution of Tetrodotoxin and Its Potential as a Therapeutic. Toxins (Basel) 2021; 13:toxins13080517. [PMID: 34437388 PMCID: PMC8402337 DOI: 10.3390/toxins13080517] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/17/2021] [Accepted: 07/20/2021] [Indexed: 11/16/2022] Open
Abstract
Tetrodotoxin (TTX) is a potent neurotoxin that was first identified in pufferfish but has since been isolated from an array of taxa that host TTX-producing bacteria. However, determining its origin, ecosystem roles, and biomedical applications has challenged researchers for decades. Recognized as a poison and for its lethal effects on humans when ingested, TTX is primarily a powerful sodium channel inhibitor that targets voltage-gated sodium channels, including six of the nine mammalian isoforms. Although lethal doses for humans range from 1.5-2.0 mg TTX (blood level 9 ng/mL), when it is administered at levels far below LD50, TTX exhibits therapeutic properties, especially to treat cancer-related pain, neuropathic pain, and visceral pain. Furthermore, TTX can potentially treat a variety of medical ailments, including heroin and cocaine withdrawal symptoms, spinal cord injuries, brain trauma, and some kinds of tumors. Here, we (i) describe the perplexing evolution and ecology of tetrodotoxin, (ii) review its mechanisms and modes of action, and (iii) offer an overview of the numerous ways it may be applied as a therapeutic. There is much to be explored in these three areas, and we offer ideas for future research that combine evolutionary biology with therapeutics. The TTX system holds great promise as a therapeutic and understanding the origin and chemical ecology of TTX as a poison will only improve its general benefit to humanity.
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Affiliation(s)
- Gary M. Bucciarelli
- Department of Ecology and Evolutionary Biology & UCLA La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095, USA; (M.L.); (H.B.S.)
- Correspondence:
| | - Maren Lechner
- Department of Ecology and Evolutionary Biology & UCLA La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095, USA; (M.L.); (H.B.S.)
| | - Audrey Fontes
- Natural Science Division, Pepperdine University, Malibu, CA 90263, USA; (A.F.); (L.B.K.)
| | - Lee B. Kats
- Natural Science Division, Pepperdine University, Malibu, CA 90263, USA; (A.F.); (L.B.K.)
| | - Heather L. Eisthen
- Department of Integrative Biology, Michigan State University, East Lansing, MI 48824, USA;
| | - H. Bradley Shaffer
- Department of Ecology and Evolutionary Biology & UCLA La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095, USA; (M.L.); (H.B.S.)
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Hijma HJ, Groeneveld GJ. Analgesic drug development: proof-of-mechanism and proof-of-concept in early phase clinical studies. MEDICINE IN DRUG DISCOVERY 2021. [DOI: 10.1016/j.medidd.2021.100083] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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Alhatali B, Al Lawatia S, Khamis F, Kantur S, Al-Abri S, Kapil V, Thomas J, Johnson R, Hamelin EI, Coleman RM, Kazzi Z. A cluster of tetrodotoxin poisoning in Oman. Clin Toxicol (Phila) 2021; 60:262-266. [PMID: 33913398 DOI: 10.1080/15563650.2021.1917595] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
INTRODUCTION Tetrodotoxin (TTX) is a potent sodium channel blocker, with significant neurotoxicity, found in marine animals like pufferfish and blue-ringed octopus. The severity of toxicity depends on the amount of toxin ingested and the outcome depends on the time-lapse to appropriate medical care. CASES REPORT We report five patients who presented with tetrodotoxin poisoning after consuming fried internal organs of local pufferfish from the coast of Oman. The patients' clinical manifestations were consistent with the expected TTX toxidrome of perioral and generalized paresthesia, weakness of upper and lower extremities, gastrointestinal manifestations, dyspnea, dysarthria, ascending paralysis, hypotension, bradycardia and coma. The severity varied among the patients who recovered completely except one patient who developed a subarachnoid hemorrhage without underlying aneurysms on computed tomography-angiogram. This complication was potentially related to TTX poisoning and has not been previously reported. In addition to standard supportive management, patients with severe illness should potentially receive the intravenous acetylcholinesterase inhibitor neostigmine, and intermittent dialysis. Urine specimens were sent to CDC in Atlanta, where they were analyzed using online solid phase extraction (SPE) with LC-MS/MS and confirmed the diagnosis in all five cases. DISCUSSION In general, the patients' clinical manifestations were consistent with the expected TTX toxidrome except patient 3 who developed a subarachnoid hemorrhage early during his clinical course. Two patients received neostigmine and underwent dialysis with complete recovery.
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Affiliation(s)
- Badria Alhatali
- Department of Environmental and Occupational Health, Directorate General for Disease Surveillance and Control, Ministry of Health, Muscat, Oman
| | | | - Faryal Khamis
- Infectious Diseases Unit, Department of Internal Medicine, Royal Hospital, Muscat, Oman
| | | | - Seif Al-Abri
- Directorate General for Disease Surveillance and Control, Ministry of Health, Muscat, Oman
| | - Vikas Kapil
- Center for Global Health, Centers for Disease Control and Prevention (CDC), Atlanta, GA, USA
| | - Jerry Thomas
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Rudolph Johnson
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Elizabeth I Hamelin
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Rebecca M Coleman
- National Biodefense Analysis and Countermeasures Center, Ft. Detrick, Frederick, MD, USA
| | - Ziad Kazzi
- Emory University School of Medicine, Atlanta, GA, USA
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Bédry R, de Haro L, Bentur Y, Senechal N, Galil BS. Toxicological risks on the human health of populations living around the Mediterranean Sea linked to the invasion of non-indigenous marine species from the Red Sea: A review. Toxicon 2021; 191:69-82. [PMID: 33359388 DOI: 10.1016/j.toxicon.2020.12.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 12/07/2020] [Accepted: 12/19/2020] [Indexed: 10/22/2022]
Abstract
The Mediterranean region is, by far, a prime travel destination, having hosted more than 330 million tourists in 2016, mostly for seaside holidays. A greatly increased influx of thermophilic Red Sea species, introduced through the Suez Canal in a process referred to as Lessepsian invasion (in honor of Ferdinand de Lesseps who instigated the building of the Suez Canal), have raised awareness among scientists, medical personnel, and the public, of health risks caused by some venomous and poisonous marine species. The main species of concern are the poisonous Lagocephalus sceleratus, and the venomous Plotosus lineatus, Siganus luridus, Siganus rivulatus, Pterois miles, Synancea verrucosa, Rhopilema nomadica, Macrorhynchia philippina and Diadema setosum. Recognizing that the main factors that drive the introduction and dispersal of Red Sea biota in the Mediterranean, i.e., Suez Canal enlargements and warming seawater, are set to increase, and international tourist arrivals are forecasted to increase as well, to 500 million in 2030, an increase in intoxications and envenomations by alien marine species is to be expected and prepared for.
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Affiliation(s)
- R Bédry
- UHSI, Pellegrin University Hospital, 33000, Bordeaux, France.
| | - L de Haro
- Centre Antipoison de Marseille, Hôpital Sainte Marguerite, 13009, Marseille, France
| | - Y Bentur
- Israel Poison Information Center, Rambam Health Care Campus, The Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - N Senechal
- Bordeaux University, UMR EPOC, 5805, Pessac, France
| | - B S Galil
- Steinhardt Museum of Natural History, Tel Aviv University, Tel Aviv, Israel
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13
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Excitability of motor and sensory axons in multifocal motor neuropathy. Clin Neurophysiol 2020; 131:2641-2650. [PMID: 32947198 DOI: 10.1016/j.clinph.2020.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Revised: 07/18/2020] [Accepted: 08/14/2020] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To assess excitability differences between motor and sensory axons of affected nerves in patients with multifocal motor neuropathy (MMN). METHODS We performed motor and sensory excitability tests in affected median nerves of 20 MMN patients and in 20 age-matched normal subjects. CMAPs were recorded from the thenar and SNAPs from the 3rd digit. Clinical tests included assessment of muscle strength, two-point discrimination and joint position. RESULTS All MMN patients had weakness of the thenar muscle and normal sensory tests. Motor excitability testing in MMN showed an increased threshold for a 50% CMAP, increased rheobase, decreased stimulus-response slope, fanning-out of threshold electrotonus, decreased resting I/V slope, shortened refractory period, and more pronounced superexcitability. Sensory excitability testing in MMN revealed decreased accommodation half-time and S2-accommodation and less pronounced subexcitability. Mathematical modeling indicated increased Barrett-Barrett conductance for motor fibers and increase in internodal fast potassium conductance for sensory fibers. CONCLUSIONS Excitability findings in MMN suggest myelin sheath or paranodal seal involvement in motor fibers and, possibly, paranodal detachment in sensory fibers. SIGNIFICANCE Excitability properties of affected nerves in MMN differ between motor and sensory nerve fibers.
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14
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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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15
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Makker PGS, White D, Lees JG, Parmar J, Goldstein D, Park SB, Howells J, Moalem-Taylor G. Acute changes in nerve excitability following oxaliplatin treatment in mice. J Neurophysiol 2020; 124:232-244. [PMID: 32519566 DOI: 10.1152/jn.00260.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Oxaliplatin chemotherapy produces acute changes in peripheral nerve excitability in humans by modulating voltage-gated Na+ channel activity. However, there are few animal studies of oxaliplatin-induced neuropathy that demonstrate similar changes in excitability. In the present study, we measured the excitability of motor and sensory caudal nerve in C57BL/6 mice after oxaliplatin injections either systemically (intraperitoneal) or locally (intramuscular at the base of the tail). As opposed to intraperitoneal administration of oxaliplatin, a single intramuscular injection of oxaliplatin produced changes in both motor and sensory axons. In motor axons, oxaliplatin caused a greater change in response to long-lasting depolarization and an upward shift in the recovery cycle, particularly at 24 h [depolarizing threshold electrotonus (TEd) 10-20 ms, P = 0.0095; TEd 90-100 ms, P = 0.0056) and 48 h (TEd 10-20 ms, P = 0.02; TEd 90-100 ms, P = 0.04) posttreatment. Oxaliplatin treatment also stimulated the production of afterdischarges in motor axons. These changes were transient and showed dose dependence. Mathematical modeling demonstrated that these changes could be accounted for by slowing inactivation of voltage-gated Na+ channels by 73.3% and reducing fast K+ conductance by 47% in motor axons. In sensory axons, oxaliplatin caused an increase in threshold, a reduction in peak amplitude, and greater threshold changes to strong hyperpolarizing currents on days 4 and 8. Thus, local administration of oxaliplatin produced clinically relevant changes in nerve excitability in mice and may provide an alternative approach for the study of acute oxaliplatin-induced neurotoxicity.NEW & NOTEWORTHY We present a novel mouse model of acute oxaliplatin-induced peripheral neurotoxicity that is comparable to clinical observations. Intramuscular injection of oxaliplatin produced acute changes in motor nerve excitability that were attributable to alterations in Na+ and K+ channel activity. Conversely, we were unable to show any significant changes in nerve excitability with systemic intraperitoneal injections of oxaliplatin. This study suggests that local intramuscular injection is a valid approach for modelling oxaliplatin-induced peripheral neuropathy in animals.
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Affiliation(s)
- Preet G S Makker
- Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales (UNSW), Sydney, New South Wales, Australia
| | - Daniel White
- Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales (UNSW), Sydney, New South Wales, Australia
| | - Justin G Lees
- Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales (UNSW), Sydney, New South Wales, Australia
| | - Jasneet Parmar
- Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales (UNSW), Sydney, New South Wales, Australia
| | - David Goldstein
- Department of Medical Oncology, Prince of Wales Hospital, Randwick, New South Wales, Australia.,Prince of Wales Clinical School, UNSW, New South Wales, Australia
| | - Susanna B Park
- Brain and Mind Centre, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - James Howells
- Central Clinical School, Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia
| | - Gila Moalem-Taylor
- Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales (UNSW), Sydney, New South Wales, Australia
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16
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Moldovan M. Threshold tracking as a tool to study activity-dependent axonal plasticity. Clin Neurophysiol 2020; 131:1381-1382. [PMID: 32224021 DOI: 10.1016/j.clinph.2020.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 03/10/2020] [Indexed: 11/26/2022]
Affiliation(s)
- Mihai Moldovan
- Department of Clinical Neurophysiology, Rigshospitalet, Copenhagen, Denmark; Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.
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17
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Klein CS, Rymer WZ, Fisher MA. Altered nerve excitability properties after stroke are potentially associated with reduced neuromuscular activation. Clin Neurophysiol 2020; 131:1407-1418. [PMID: 32184063 DOI: 10.1016/j.clinph.2020.02.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 01/22/2020] [Accepted: 02/16/2020] [Indexed: 12/17/2022]
Abstract
OBJECTIVE To determine limb differences in motor axon excitability properties in stroke survivors and their relation to maximal electromyographic (EMG) activity. METHODS The median nerve was stimulated to record compound muscle action potentials (CMAP) from the abductor pollicis brevis (APB) in 28 stroke subjects (57.3 ± 7.5 y) and 24 controls (56.7 ± 9.3 y). RESULTS Paretic limb axons differed significantly from non-paretic limb axons including (1) smaller superexcitability and subexcitability, (2) higher threshold during subthreshold depolarizing currents, (3) greater accommodation (S3) to hyperpolarization, and (4) a larger stimulus-response slope. There were smaller differences between the paretic and control limbs. Responses in the paretic limb were reproduced in a model by a 5.6 mV hyperpolarizing shift in the activation voltage of Ih (the current activated by hyperpolarization), together with an 11.8% decrease in nodal Na+ conductance or a 0.9 mV depolarizing shift in the Na+ activation voltage. Subjects with larger deficits in APB maximal voluntary EMG had larger limb differences in excitability properties. CONCLUSIONS Stroke leads to altered modulation of Ih and altered Na+ channel properties that may be partially attributed to a reduction in neuromuscular activation. SIGNIFICANCE Plastic changes occur in the axon node and internode that likely influence axon excitability.
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Affiliation(s)
- C S Klein
- Guangdong Work Injury Rehabilitation Center, Guangzhou 510440, China; Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL 60611, USA.
| | - W Z Rymer
- Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL 60611, USA; Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - M A Fisher
- Department of Neurology, Hines VAH, Hines, IL 60141, USA; Loyola University Chicago Medical Center, 2160 S. First Ave., Maywood, IL 60153, USA
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18
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Tummanapalli SS, Issar T, Kwai N, Poynten A, Krishnan AV, Willcox M, Markoulli M. Association of corneal nerve loss with markers of axonal ion channel dysfunction in type 1 diabetes. Clin Neurophysiol 2020; 131:145-154. [DOI: 10.1016/j.clinph.2019.09.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 08/29/2019] [Accepted: 09/29/2019] [Indexed: 01/06/2023]
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19
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Alberti P, Canta A, Chiorazzi A, Fumagalli G, Meregalli C, Monza L, Pozzi E, Ballarini E, Rodriguez-Menendez V, Oggioni N, Sancini G, Marmiroli P, Cavaletti G. Topiramate prevents oxaliplatin-related axonal hyperexcitability and oxaliplatin induced peripheral neurotoxicity. Neuropharmacology 2019; 164:107905. [PMID: 31811874 DOI: 10.1016/j.neuropharm.2019.107905] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 11/26/2019] [Accepted: 12/03/2019] [Indexed: 12/15/2022]
Abstract
Oxaliplatin (OHP) Induced Peripheral Neurotoxicity (OIPN) is one of the dose-limiting toxicities of the drug and these adverse effects limit cancer therapy with L-OHP, used for colorectal cancer treatment. Acute neurotoxicity consists of symptoms that are the hallmarks of a transient axonal hyperexcitability; chronic neurotoxicity has a clinical picture compatible with a length-dependent sensory neuropathy. Acute OIPN pathogenesis has been linked to sodium voltage-operated channels (Na + VOC) dysfunction and it has been advocated as a possible predisposing factor to chronic neurotoxicity. We tested if topiramate (TPM), a well-known Na + VOC modulator, was able to modify acute as well as chronic OIPN. The project was divided into two parts. In Experiment 1 we tested by means of Nerve Excitability Testing (NET) a cohort of female Wistar rats to assess TPM effects after a single OHP administration (5 mg/kg, iv). In Experiment 2 we assessed TPM effects after chronic OHP treatment (5 mg/kg, 2qw4ws, iv) using NET, nerve conduction studies (NCS), behavioral tests and neuropathology (caudal nerve morphometry and morphology and Intraepidermal Nerve Fiber [IENF] density). In Experiment 1 TPM was able to prevent OHP effects on Na + VOC: OHP treatment induced a highly significant reduction of the sensory nerve's threshold, during the superexcitability period (p-value = 0.008), whereas TPM co-administration prevented this effect. In Experiment 2 we verified that TPM was able to prevent not only acute phenomena, but also to completely prevent chronic OIPN. This latter observation was supported by a multimodal approach: in fact, only OHP group showed altered findings compared to CTRL group at a neurophysiological (proximal caudal nerve sensory nerve action potential [SNAP] amplitude, p-value = 0.001; distal caudal nerve SNAP amplitude, p-value<0.001, distal caudal nerve sensory conduction velocity, p-value = 0.04), behavioral (mechanical threshold, p-value 0.003) and neuropathological levels (caudal nerve fibers density, p-value 0.001; IENF density, p-value <0.001). Our data show that TPM is a promising drug to prevent both acute and chronic OIPN. These findings have a high translational potential, since they were obtained using outcome measures that match clinical practice and TPM is already approved for clinical use being free from detrimental interaction with OHP anticancer properties.
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Affiliation(s)
- Paola Alberti
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy; NeuroMI (Milan Center for Neuroscience), School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy.
| | - Annalisa Canta
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy; NeuroMI (Milan Center for Neuroscience), School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy
| | - Alessia Chiorazzi
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy; NeuroMI (Milan Center for Neuroscience), School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy
| | - Giulia Fumagalli
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy; NeuroMI (Milan Center for Neuroscience), School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy; PhD program in Neuroscience, School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy
| | - Cristina Meregalli
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy; NeuroMI (Milan Center for Neuroscience), School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy
| | - Laura Monza
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy; NeuroMI (Milan Center for Neuroscience), School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy; Human Physiology Lab., School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy
| | - Eleonora Pozzi
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy; NeuroMI (Milan Center for Neuroscience), School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy; PhD program in Neuroscience, School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy
| | - Elisa Ballarini
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy; NeuroMI (Milan Center for Neuroscience), School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy
| | - Virginia Rodriguez-Menendez
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy; NeuroMI (Milan Center for Neuroscience), School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy
| | - Norberto Oggioni
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy; NeuroMI (Milan Center for Neuroscience), School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy
| | - Giulio Sancini
- NeuroMI (Milan Center for Neuroscience), School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy; Human Physiology Lab., School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy
| | - Paola Marmiroli
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy; NeuroMI (Milan Center for Neuroscience), School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy
| | - Guido Cavaletti
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy; NeuroMI (Milan Center for Neuroscience), School of Medicine and Surgery, University of Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy
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20
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Kamel J, Loh M, Cook M, MacIsaac RJ, Roberts LJ. Reducing glucose variability with continuous subcutaneous insulin infusion is associated with reversal of axonal dysfunction in type 1 diabetes mellitus. Muscle Nerve 2019; 61:44-51. [DOI: 10.1002/mus.26738] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 09/30/2019] [Accepted: 10/09/2019] [Indexed: 01/20/2023]
Affiliation(s)
- Jordan Kamel
- Department of Neurology and Neurological Research St Vincent's Hospital Melbourne Melbourne Victoria Australia
- Department of Medicine The University of Melbourne Victoria Australia
| | - Margaret Loh
- Department of Endocrinology and Diabetes St Vincent's Hospital Melbourne Victoria Australia
| | - Mark Cook
- Department of Neurology and Neurological Research St Vincent's Hospital Melbourne Melbourne Victoria Australia
- Department of Medicine The University of Melbourne Victoria Australia
| | - Richard J. MacIsaac
- Department of Medicine The University of Melbourne Victoria Australia
- Department of Endocrinology and Diabetes St Vincent's Hospital Melbourne Victoria Australia
| | - Leslie J. Roberts
- Department of Neurology and Neurological Research St Vincent's Hospital Melbourne Melbourne Victoria Australia
- Department of Medicine The University of Melbourne Victoria Australia
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21
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Sleutjes BTHM, Kovalchuk MO, Durmus N, Buitenweg JR, van Putten MJAM, van den Berg LH, Franssen H. Simulating perinodal changes observed in immune-mediated neuropathies: impact on conduction in a model of myelinated motor and sensory axons. J Neurophysiol 2019; 122:1036-1049. [PMID: 31291151 DOI: 10.1152/jn.00326.2019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Immune-mediated neuropathies affect myelinated axons, resulting in conduction slowing or block that may affect motor and sensory axons differently. The underlying mechanisms of these neuropathies are not well understood. Using a myelinated axon model, we studied the impact of perinodal changes on conduction. We extended a longitudinal axon model (41 nodes of Ranvier) with biophysical properties unique to human myelinated motor and sensory axons. We simulated effects of temperature and axonal diameter on conduction and strength-duration properties. We then studied effects of impaired nodal sodium channel conductance and paranodal myelin detachment by reducing periaxonal resistance, as well as their interaction, on conduction in the 9 middle nodes and enclosed paranodes. Finally, we assessed the impact of reducing the affected region (5 nodes) and adding nodal widening. Physiological motor and sensory conduction velocities and changes to axonal diameter and temperature were observed. The sensory axon had a longer strength-duration time constant. Reducing sodium channel conductance and paranodal periaxonal resistance induced progressive conduction slowing. In motor axons, conduction block occurred with a 4-fold drop in sodium channel conductance or a 7.7-fold drop in periaxonal resistance. In sensory axons, block arose with a 4.8-fold drop in sodium channel conductance or a 9-fold drop in periaxonal resistance. This indicated that motor axons are more vulnerable to developing block. A boundary of block emerged when the two mechanisms interacted. This boundary shifted in opposite directions for a smaller affected region and nodal widening. These differences may contribute to the predominance of motor deficits observed in some immune-mediated neuropathies.NEW & NOTEWORTHY Immune-mediated neuropathies may affect myelinated motor and sensory axons differently. By the development of a computational model, we quantitatively studied the impact of perinodal changes on conduction in motor and sensory axons. Simulations of increasing nodal sodium channel dysfunction and paranodal myelin detachment induced progressive conduction slowing. Sensory axons were more resistant to block than motor axons. This could explain the greater predisposition of motor axons to functional deficits observed in some immune-mediated neuropathies.
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Affiliation(s)
- Boudewijn T H M Sleutjes
- Department of Neurology, Brain Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Maria O Kovalchuk
- Department of Neurology, Brain Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Naric Durmus
- Biomedical Signals and Systems, MIRA, Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands.,Department of Clinical Neurophysiology, University of Twente, Enschede, The Netherlands
| | - Jan R Buitenweg
- Biomedical Signals and Systems, MIRA, Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Michel J A M van Putten
- Department of Clinical Neurophysiology, University of Twente, Enschede, The Netherlands.,Department of Neurology and Clinical Neurophysiology, Medisch Spectrum Twente, Enschede, The Netherlands
| | - Leonard H van den Berg
- Department of Neurology, Brain Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Hessel Franssen
- Department of Neurology, Brain Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands
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22
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Huang CW, Lai HJ, Huang PY, Lee MJ, Kuo CC. Anomalous enhancement of resurgent Na + currents at high temperatures by SCN9A mutations underlies the episodic heat-enhanced pain in inherited erythromelalgia. Sci Rep 2019; 9:12251. [PMID: 31439884 PMCID: PMC6706385 DOI: 10.1038/s41598-019-48672-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 08/09/2019] [Indexed: 01/12/2023] Open
Abstract
Inherited erythromelalgia (IEM), caused by mutations in Nav1.7 channel is characterized by episodic neuropathic pain triggered especially by warm temperature. However, the mechanism underlying the temperature–dependent episodic attacks of IEM remains elusive. We investigated the electrophysiological effect of temperature changes on Nav1.7 channels with three different mutations, p.I136V, p. I848T, and p.V1316A, both in vitro and in vivo. In vitro biophysical studies of the mutant channels show consistent temperature-dependent enhancement of the relative resurgent currents if normalized to the transient currents, as well as temperature-dependent changes in the time to peak and the kinetics of decay of the resurgent currents, but no congruent temperature–dependent changes in steady–state parameters such as shift of activation/inactivation curves and changes of the absolute size of the window or resurgent currents. In vivo nerve excitability tests (NET) in IEM patients reveal the essentially normal indices of NET at a single stimulus. However, there are evident abnormalities if assessed with preconditioning pulses, such as the decrease of threshold elevation in hyperpolarizing threshold electrotonus (50–100 ms), the increase of inward rectification in current–voltage curve, and the increase of refractoriness at the interpulse interval of 2–6 ms in recovery cycle, probably also implicating derangements in temperature dependence of inactivation and of recovery from inactivation in the mutant channels. The pathogenesis of heat–enhanced pain in IEM could be attributed to deranged temperature dependence of Nav1.7 channels responsible for the genesis of resurgent currents.
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Affiliation(s)
- Chiung-Wei Huang
- Department of Physiology, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Hsing-Jung Lai
- Department of Physiology, National Taiwan University College of Medicine, Taipei, Taiwan.,Department of Neurology, National Taiwan University Hospital Jinshan Branch, New Taipei City, Taiwan.,Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
| | - Po-Yuan Huang
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
| | - Ming-Jen Lee
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan. .,Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan.
| | - Chung-Chin Kuo
- Department of Physiology, National Taiwan University College of Medicine, Taipei, Taiwan. .,Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan.
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23
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Issar T, Arnold R, Kwai NCG, Walker S, Yan A, Borire AA, Poynten AM, Pussell BA, Endre ZH, Kiernan MC, Krishnan AV. Relative contributions of diabetes and chronic kidney disease to neuropathy development in diabetic nephropathy patients. Clin Neurophysiol 2019; 130:2088-2095. [PMID: 31541986 DOI: 10.1016/j.clinph.2019.08.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 07/04/2019] [Accepted: 08/12/2019] [Indexed: 12/12/2022]
Abstract
OBJECTIVE Chronic kidney disease (CKD) caused by diabetes is known as diabetic kidney disease (DKD). The present study aimed to examine the underlying mechanisms of axonal dysfunction and features of neuropathy in DKD compared to CKD and type 2 diabetes (T2DM) alone. METHODS Patients with DKD (n = 30), CKD (n = 28) or T2DM (n = 40) and healthy controls (n = 41) underwent nerve excitability assessments to examine axonal function. Neuropathy was assessed using the Total Neuropathy Score. A validated mathematical model of human axons was utilised to provide an indication of the underlying causes of nerve pathophysiology. RESULTS Total neuropathy score was significantly higher in patients with DKD compared to those with either CKD or T2DM (p < 0.05). In DKD, nerve excitability measures (S2 accommodation and superexcitability, p < 0.05) were more severely affected compared to both CKD and T2DM and worsened with increasing serum K+ (p < 0.01). Mathematical modelling indicated the basis for nerve dysfunction in DKD was an elevation of extracellular K+ and reductions in Na+ permeability and the hyperpolarisation-activated cation current, which was similar to CKD. CONCLUSIONS Patients with DKD manifested a more severe neuropathy phenotype and shared features of nerve dysfunction to that of CKD. SIGNIFICANCE The CKD, and not diabetes component, appears to underlie axonal pathophysiology in DKD.
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Affiliation(s)
- Tushar Issar
- Prince of Wales Clinical School, UNSW Sydney, NSW 2031, Australia
| | - Ria Arnold
- School of Medical Sciences, UNSW Sydney, NSW 2052, Australia
| | - Natalie C G Kwai
- Prince of Wales Clinical School, UNSW Sydney, NSW 2031, Australia; Department of Exercise Physiology, UNSW Sydney, NSW 2052, Australia
| | - Susan Walker
- Prince of Wales Clinical School, UNSW Sydney, NSW 2031, Australia
| | - Aimy Yan
- Prince of Wales Clinical School, UNSW Sydney, NSW 2031, Australia
| | - Adeniyi A Borire
- Prince of Wales Clinical School, UNSW Sydney, NSW 2031, Australia
| | - Ann M Poynten
- Department of Endocrinology, Prince of Wales Hospital, Sydney, NSW 2031, Australia
| | - Bruce A Pussell
- Department of Nephrology, Prince of Wales Hospital, Sydney, NSW 2031, Australia
| | - Zoltan H Endre
- Department of Nephrology, Prince of Wales Hospital, Sydney, NSW 2031, Australia
| | - Matthew C Kiernan
- Brain and Mind Centre, University of Sydney and Royal Prince Alfred Hospital, Sydney, NSW 2050, Australia
| | - Arun V Krishnan
- Prince of Wales Clinical School, UNSW Sydney, NSW 2031, Australia.
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24
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Kiernan MC, Bostock H, Park SB, Kaji R, Krarup C, Krishnan AV, Kuwabara S, Lin CSY, Misawa S, Moldovan M, Sung J, Vucic S, Wainger BJ, Waxman S, Burke D. Measurement of axonal excitability: Consensus guidelines. Clin Neurophysiol 2019; 131:308-323. [PMID: 31471200 DOI: 10.1016/j.clinph.2019.07.023] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 07/17/2019] [Accepted: 07/24/2019] [Indexed: 12/12/2022]
Abstract
Measurement of axonal excitability provides an in vivo indication of the properties of the nerve membrane and of the ion channels expressed on these axons. Axonal excitability techniques have been utilised to investigate the pathophysiological mechanisms underlying neurological diseases. This document presents guidelines derived for such studies, based on a consensus of international experts, and highlights the potential difficulties when interpreting abnormalities in diseased axons. The present manuscript provides a state-of-the-art review of the findings of axonal excitability studies and their interpretation, in addition to suggesting guidelines for the optimal performance of excitability studies.
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Affiliation(s)
- Matthew C Kiernan
- Brain and Mind Centre, University of Sydney and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney 2006, Australia.
| | - Hugh Bostock
- UCL Queen Square Institute of Neurology, London WC1N 3BG, United Kingdom
| | - Susanna B Park
- Brain and Mind Centre, University of Sydney and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney 2006, Australia
| | - Ryuji Kaji
- National Utano Hospital, 8-Narutaki Ondoyamacho, Ukyoku, Kyoto 616-8255, Japan
| | - Christian Krarup
- Department of Neuroscience, University of Copenhagen and Department of Clinical Neurophysiology, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Arun V Krishnan
- Prince of Wales Clinical School, University of New South Wales, Sydney, Australia
| | - Satoshi Kuwabara
- Department of Neurology, Graduate School of Medicine, Chiba University, Japan
| | - Cindy Shin-Yi Lin
- Brain and Mind Centre, University of Sydney and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney 2006, Australia
| | - Sonoko Misawa
- Department of Neurology, Graduate School of Medicine, Chiba University, Japan
| | - Mihai Moldovan
- Department of Neuroscience, University of Copenhagen and Department of Clinical Neurophysiology, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Jiaying Sung
- Taipei Medical University, Wanfang Hospital, Taipei, Taiwan
| | - Steve Vucic
- Department of Neurology, Westmead Hospital, Western Clinical School, University of Sydney, Australia
| | - Brian J Wainger
- Department of Neurology and Anesthesiology, Critical Care & Pain Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Stephen Waxman
- Department of Neurology, Yale Medical School, New Haven, CT 06510, USA; Neurorehabilitation Research Center, Veterans Affairs Hospital, West Haven, CT 06516, USA
| | - David Burke
- Brain and Mind Centre, University of Sydney and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney 2006, Australia
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25
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From Perception Threshold to Ion Channels-A Computational Study. Biophys J 2019; 117:281-295. [PMID: 31255293 DOI: 10.1016/j.bpj.2019.04.041] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 02/20/2019] [Accepted: 04/22/2019] [Indexed: 01/24/2023] Open
Abstract
Small-surface-area electrodes have successfully been used to preferentially activate cutaneous nociceptors, unlike conventional large area-electrodes, which preferentially activate large non-nociceptor fibers. Assessments of the strength-duration relationship, threshold electrotonus, and slowly increasing pulse forms have displayed different perception thresholds between large and small surface electrodes, which may indicate different excitability properties of the activated cutaneous nerves. In this study, the origin of the differences in perception thresholds between the two electrodes was investigated. It was hypothesized that different perception thresholds could be explained by the varying distributions of voltage-gated ion channels and by morphological differences between peripheral nerve endings of small and large fibers. A two-part computational model was developed to study activation of peripheral nerve fibers by different cutaneous electrodes. The first part of the model was a finite-element model, which calculated the extracellular field delivered by the cutaneous electrodes. The second part of the model was a detailed multicompartment model of an Aδ-axon as well as an Aβ-axon. The axon models included a wide range of voltage-gated ion channels: NaTTXs, NaTTXr, Nap, Kdr, KM, KA, and HCN channel. The computational model reproduced the experimentally assessed perception thresholds for the three protocols, the strength-duration relationship, the threshold electrotonus, and the slowly increasing pulse forms. The results support the hypothesis that voltage-gated ion channel distributions and morphology differences between small and large fibers were sufficient to explain the difference in perception thresholds between the two electrodes. In conclusion, assessments of perception thresholds using the three protocols may be an indirect measurement of the membrane excitability, and computational models may have the possibility to link voltage-gated ion channel activation to perception threshold measurements.
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26
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Garg N, Park SB, Howells J, Vucic S, Yiannikas C, Mathey EK, Nguyen T, Noto Y, Barnett MH, Krishnan AV, Spies J, Bostock H, Pollard JD, Kiernan MC. Conduction block in immune-mediated neuropathy: paranodopathy versus axonopathy. Eur J Neurol 2019; 26:1121-1129. [PMID: 30882969 DOI: 10.1111/ene.13953] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 03/11/2019] [Indexed: 12/15/2022]
Abstract
BACKGROUND AND PURPOSE Conduction block is a pathognomonic feature of immune-mediated neuropathies. The aim of this study was to advance understanding of pathophysiology and conduction block in chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy (MMN). METHODS A multimodal approach was used, incorporating clinical phenotyping, neurophysiology, immunohistochemistry and structural assessments. RESULTS Of 49 CIDP and 14 MMN patients, 25% and 79% had median nerve forearm block, respectively. Clinical scores were similar in CIDP patients with and without block. CIDP patients with median nerve block demonstrated markedly elevated thresholds and greater threshold changes in threshold electrotonus, whilst those without did not differ from healthy controls in electrotonus parameters. In contrast, MMN patients exhibited marked increases in superexcitability. Nerve size was similar in both CIDP groups at the site of axonal excitability. However, CIDP patients with block demonstrated more frequent paranodal serum binding to teased rat nerve fibres. In keeping with these findings, mathematical modelling of nerve excitability recordings in CIDP patients with block support the role of paranodal dysfunction and enhanced leakage of current between the node and internode. In contrast, changes in MMN probably resulted from a reduction in ion channel density along axons. CONCLUSIONS The underlying pathologies in CIDP and MMN are distinct. Conduction block in CIDP is associated with paranodal dysfunction which may be antibody-mediated in a subset of patients. In contrast, MMN is characterized by channel dysfunction downstream from the site of block.
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Affiliation(s)
- N Garg
- Brain and Mind Centre, Sydney Medical School, University of Sydney, Sydney, NSW, Australia.,Department of Neurology, Royal Prince Alfred Hospital, Sydney, NSW, Australia
| | - S B Park
- Brain and Mind Centre, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - J Howells
- Brain and Mind Centre, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - S Vucic
- Departments of Neurology and Neurophysiology, Westmead Hospital, University of Sydney, Sydney, NSW, Australia
| | - C Yiannikas
- Department of Neurology, Concord and Royal North Shore Hospitals, University of Sydney, Sydney, NSW, Australia
| | - E K Mathey
- Brain and Mind Centre, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - T Nguyen
- Brain and Mind Centre, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Y Noto
- Brain and Mind Centre, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - M H Barnett
- Brain and Mind Centre, Sydney Medical School, University of Sydney, Sydney, NSW, Australia.,Department of Neurology, Royal Prince Alfred Hospital, Sydney, NSW, Australia
| | - A V Krishnan
- Prince of Wales Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - J Spies
- Brain and Mind Centre, Sydney Medical School, University of Sydney, Sydney, NSW, Australia.,Department of Neurology, Royal Prince Alfred Hospital, Sydney, NSW, Australia
| | - H Bostock
- MRC Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, London, UK.,Institute of Neurology, University College London, London, UK
| | - J D Pollard
- Brain and Mind Centre, Sydney Medical School, University of Sydney, Sydney, NSW, Australia.,Department of Neurology, Royal Prince Alfred Hospital, Sydney, NSW, Australia
| | - M C Kiernan
- Brain and Mind Centre, Sydney Medical School, University of Sydney, Sydney, NSW, Australia.,Department of Neurology, Royal Prince Alfred Hospital, Sydney, NSW, Australia
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27
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McDermott LA, Weir GA, Themistocleous AC, Segerdahl AR, Blesneac I, Baskozos G, Clark AJ, Millar V, Peck LJ, Ebner D, Tracey I, Serra J, Bennett DL. Defining the Functional Role of Na V1.7 in Human Nociception. Neuron 2019; 101:905-919.e8. [PMID: 30795902 PMCID: PMC6424805 DOI: 10.1016/j.neuron.2019.01.047] [Citation(s) in RCA: 116] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 12/03/2018] [Accepted: 01/18/2019] [Indexed: 12/17/2022]
Abstract
Loss-of-function mutations in NaV1.7 cause congenital insensitivity to pain (CIP); this voltage-gated sodium channel is therefore a key target for analgesic drug development. Utilizing a multi-modal approach, we investigated how NaV1.7 mutations lead to human pain insensitivity. Skin biopsy and microneurography revealed an absence of C-fiber nociceptors in CIP patients, reflected in a reduced cortical response to capsaicin on fMRI. Epitope tagging of endogenous NaV1.7 revealed the channel to be localized at the soma membrane, axon, axon terminals, and the nodes of Ranvier of induced pluripotent stem cell (iPSC) nociceptors. CIP patient-derived iPSC nociceptors exhibited an inability to properly respond to depolarizing stimuli, demonstrating that NaV1.7 is a key regulator of excitability. Using this iPSC nociceptor platform, we found that some NaV1.7 blockers undergoing clinical trials lack specificity. CIP, therefore, arises due to a profound loss of functional nociceptors, which is more pronounced than that reported in rodent models, or likely achievable following acute pharmacological blockade. VIDEO ABSTRACT.
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Affiliation(s)
- Lucy A McDermott
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Greg A Weir
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | | | - Andrew R Segerdahl
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK; Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Iulia Blesneac
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Georgios Baskozos
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Alex J Clark
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Val Millar
- Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7FZ, UK
| | - Liam J Peck
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Daniel Ebner
- Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7FZ, UK
| | - Irene Tracey
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK; Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Jordi Serra
- Department of Clinical Neurophysiology, King's College Hospital, London SE5 9RS, UK
| | - David L Bennett
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
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28
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Howells J, Matamala JM, Park SB, Garg N, Vucic S, Bostock H, Burke D, Kiernan MC. In vivo evidence for reduced ion channel expression in motor axons of patients with amyotrophic lateral sclerosis. J Physiol 2018; 596:5379-5396. [PMID: 30175403 DOI: 10.1113/jp276624] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 08/31/2018] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS The progressive loss of motor units in amyotrophic lateral sclerosis (ALS) is initially compensated for by the reinnervation of denervated muscle fibres by surviving motor axons. A disruption in protein homeostasis is thought to play a critical role in the pathogenesis of ALS. The changes in surviving motor neurons were studied by comparing the nerve excitability properties of moderately and severely affected single motor axons from patients with ALS with those from single motor axons in control subjects. A mathematical model indicated that approximately 99% of the differences between the ALS and control units could be explained by a non-selective reduction in the expression of all ion channels. These changes in ALS patients are best explained by a failure in the supply of ion channel and other membrane proteins from the diseased motor neuron. ABSTRACT Amyotrophic lateral sclerosis (ALS) is characterised by a progressive loss of motor units and the reinnervation of denervated muscle fibres by surviving motor axons. This reinnervation preserves muscle function until symptom onset, when some 60-80% of motor units have been lost. We have studied the changes in surviving motor neurons by comparing the nerve excitability properties of 31 single motor axons from patients with ALS with those from 21 single motor axons in control subjects. ALS motor axons were classified as coming from moderately or severely affected muscles according to the compound muscle action potential amplitude of the parent muscle. Compared with control units, thresholds were increased, and there was reduced inward and outward rectification and greater superexcitability following a conditioning impulse. These abnormalities were greater in axons from severely affected muscles, and were correlated with loss of fine motor skills. A mathematical model indicated that 99.1% of the differences between the moderately affected ALS and control units could be explained by a reduction in the expression of all ion channels. For the severely affected units, modelling required, in addition, an increase in the current leak through and under the myelin sheath. This might be expected if the anchoring proteins responsible for the paranodal seal were reduced. We conclude that changes in axonal excitability identified in ALS patients are best explained by a failure in the supply of ion channel and other membrane proteins from the diseased motor neuron, a conclusion consistent with recent animal and in vitro human data.
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Affiliation(s)
- James Howells
- Brain & Mind Centre, University of Sydney, Sydney, Australia
| | | | - Susanna B Park
- Brain & Mind Centre, University of Sydney, Sydney, Australia
| | - Nidhi Garg
- Brain & Mind Centre, University of Sydney, Sydney, Australia.,Institute of Clinical Neurosciences, Royal Prince Alfred Hospital and University of Sydney, Sydney, Australia
| | - Steve Vucic
- Departments of Neurology and Neurophysiology, Westmead Hospital and University of Sydney, Sydney, Australia
| | - Hugh Bostock
- MRC Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK.,Institute of Neurology, UCL, Queen Square, London, WC1N 3BG, UK
| | - David Burke
- Institute of Clinical Neurosciences, Royal Prince Alfred Hospital and University of Sydney, Sydney, Australia
| | - Matthew C Kiernan
- Brain & Mind Centre, University of Sydney, Sydney, Australia.,Institute of Clinical Neurosciences, Royal Prince Alfred Hospital and University of Sydney, Sydney, Australia
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29
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Garg N, Park SB, Howells J, Noto YI, Vucic S, Yiannikas C, Tomlinson SE, Huynh W, Simon NG, Mathey EK, Spies J, Pollard JD, Krishnan AV, Kiernan MC. Anti-MAG neuropathy: Role of IgM antibodies, the paranodal junction and juxtaparanodal potassium channels. Clin Neurophysiol 2018; 129:2162-2169. [PMID: 30144659 DOI: 10.1016/j.clinph.2018.07.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 06/12/2018] [Accepted: 07/15/2018] [Indexed: 12/14/2022]
Abstract
OBJECTIVE To improve understanding of disease pathophysiology in anti-myelin-associated glycoprotein (anti-MAG) neuropathy to guide further treatment approaches. METHODS Anti-MAG neuropathy patients underwent clinical assessments, nerve conduction and excitability studies, and ultrasound assessment. RESULTS Patients demonstrated a distinctive axonal excitability profile characterised by a reduction in superexcitability [MAG: -14.2 ± 1.6% vs healthy controls (HC): -21.8 ± 1.2%; p < 0.01] without alterations in most other excitability parameters. Mathematical modelling of nerve excitability recordings suggested that changes in axonal function could be explained by a 72.5% increase in juxtaparanodal fast potassium channel activation and an accompanying hyperpolarization of resting membrane potential (by 0.3 mV) resulting in a 94.2% reduction in discrepancy between anti-MAG data and the healthy control model. Superexcitability changes correlated strongly with clinical and neurophysiological parameters. Furthermore, structural assessments demonstrated a proximal pattern of nerve enlargement (C6 nerve root cross-sectional area: 15.9 ± 8.1 mm2 vs HC: 9.1 ± 2.3 mm2; p < 0.05). CONCLUSIONS The imaging and neurophysiological results support the pathogenicity of anti-MAG IgM. Widening between adjacent loops of paranodal myelin due to antibodies would expand the pathway from the node to the juxtaparanode, increasing activation of juxtaparanodal fast potassium channels, thereby impairing saltatory conduction. SIGNIFICANCE Potassium channel blockers may prove beneficial in restoring conduction closer to its normal state and improving nerve function in anti-MAG neuropathy.
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Affiliation(s)
- Nidhi Garg
- Brain and Mind Centre, Sydney Medical School, The University of Sydney, 94 Mallett St, Camperdown, NSW 2050, Australia.
| | - Susanna B Park
- Brain and Mind Centre, Sydney Medical School, The University of Sydney, 94 Mallett St, Camperdown, NSW 2050, Australia.
| | - James Howells
- Brain and Mind Centre, Sydney Medical School, The University of Sydney, 94 Mallett St, Camperdown, NSW 2050, Australia.
| | - Yu-Ichi Noto
- Brain and Mind Centre, Sydney Medical School, The University of Sydney, 94 Mallett St, Camperdown, NSW 2050, Australia.
| | - Steve Vucic
- Departments of Neurology and Neurophysiology, Westmead Hospital, The University of Sydney, NSW, Australia.
| | - Con Yiannikas
- Department of Neurology, Concord and Royal North Shore Hospitals, The University of Sydney, NSW, Australia.
| | - Susan E Tomlinson
- Sydney Medical School, University of Sydney, Sydney, Australia; Department of Neurology, St Vincent's Hospital, Sydney, Australia.
| | - William Huynh
- Brain and Mind Centre, Sydney Medical School, The University of Sydney, 94 Mallett St, Camperdown, NSW 2050, Australia.
| | - Neil G Simon
- St Vincent's Clinical School, University of New South Wales, NSW, Australia.
| | - Emily K Mathey
- Brain and Mind Centre, Sydney Medical School, The University of Sydney, 94 Mallett St, Camperdown, NSW 2050, Australia.
| | - Judith Spies
- Brain and Mind Centre, Sydney Medical School, The University of Sydney, 94 Mallett St, Camperdown, NSW 2050, Australia.
| | - John D Pollard
- Brain and Mind Centre, Sydney Medical School, The University of Sydney, 94 Mallett St, Camperdown, NSW 2050, Australia.
| | - Arun V Krishnan
- Prince of Wales Clinical School, University of New South Wales, NSW, Australia.
| | - Matthew C Kiernan
- Brain and Mind Centre, Sydney Medical School, The University of Sydney, 94 Mallett St, Camperdown, NSW 2050, Australia.
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30
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Moldovan M, Alvarez S, Rothe C, Andresen TL, Urquhart A, Lange KHW, Krarup C. An in Vivo Mouse Model to Investigate the Effect of Local Anesthetic Nanomedicines on Axonal Conduction and Excitability. Front Neurosci 2018; 12:494. [PMID: 30093852 PMCID: PMC6070635 DOI: 10.3389/fnins.2018.00494] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 07/02/2018] [Indexed: 11/13/2022] Open
Abstract
Peripheral nerve blocks (PNBs) using local anesthetic (LA) are superior to systemic analgesia for management of post-operative pain. An insufficiently short PNB duration following single-shot LA can be optimized by development of extended release formulations among which liposomes have been shown to be the least toxic. In vivo rodent models for PNB have focused primarily on assessing behavioral responses following LA. In a previous study in human volunteers, we found that it is feasible to monitor the effect of LA in vivo by combining conventional conduction studies with nerve excitability studies. Here, we aimed to develop a mouse model where the same neurophysiological techniques can be used to investigate liposomal formulations of LA in vivo. To challenge the validity of the model, we tested the motor PNB following an unilamellar liposomal formulation, filled with the intermediate-duration LA lidocaine. Experiments were carried out in adult transgenic mice with fluorescent axons and with fluorescent tagged liposomes to allow in vivo imaging by probe-based confocal laser endomicroscopy. Recovery of conduction following LA injection at the ankle was monitored by stimulation of the tibial nerve fibers at the sciatic notch and recording of the plantar compound motor action potential (CMAP). We detected a delayed recovery in CMAP amplitude following liposomal lidocaine, without detrimental systemic effects. Furthermore, CMAP threshold-tracking studies of the distal tibial nerve showed that the increased rheobase was associated with a sequence of excitability changes similar to those found following non-encapsulated lidocaine PNB in humans, further supporting the translational value of the model.
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Affiliation(s)
- Mihai Moldovan
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.,Department of Clinical Neurophysiology, Rigshospitalet, Copenhagen, Denmark
| | - Susana Alvarez
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Christian Rothe
- Department of Anesthesia, Nordsjællands Hospital, Hillerød, Denmark
| | - Thomas L Andresen
- Department for Micro- and Nanotechnology, Technical University of Denmark, Lyngby, Denmark
| | - Andrew Urquhart
- Department for Micro- and Nanotechnology, Technical University of Denmark, Lyngby, Denmark
| | - Kai H W Lange
- Department of Anesthesia, Nordsjællands Hospital, Hillerød, Denmark
| | - Christian Krarup
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.,Department of Clinical Neurophysiology, Rigshospitalet, Copenhagen, Denmark
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31
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Makker PGS, Matamala JM, Park SB, Lees JG, Kiernan MC, Burke D, Moalem‐Taylor G, Howells J. A unified model of the excitability of mouse sensory and motor axons. J Peripher Nerv Syst 2018; 23:159-173. [DOI: 10.1111/jns.12278] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Revised: 06/13/2018] [Accepted: 06/13/2018] [Indexed: 11/29/2022]
Affiliation(s)
- Preet G. S. Makker
- School of Medical SciencesUniversity of New South Wales Sydney Australia
| | | | - Susanna B. Park
- Brain and Mind CentreThe University of Sydney Sydney Australia
| | - Justin G. Lees
- School of Medical SciencesUniversity of New South Wales Sydney Australia
| | - Matthew C. Kiernan
- Brain and Mind CentreThe University of Sydney Sydney Australia
- Royal Prince Alfred HospitalThe University of Sydney Sydney Australia
| | - David Burke
- Royal Prince Alfred HospitalThe University of Sydney Sydney Australia
| | - Gila Moalem‐Taylor
- School of Medical SciencesUniversity of New South Wales Sydney Australia
| | - James Howells
- Brain and Mind CentreThe University of Sydney Sydney Australia
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32
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Howells J, Bostock H, Park SB, Kiernan MC, Burke D. Tracking small sensory nerve action potentials in human axonal excitability studies. J Neurosci Methods 2018; 298:45-53. [DOI: 10.1016/j.jneumeth.2018.02.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 01/08/2018] [Accepted: 02/08/2018] [Indexed: 10/18/2022]
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33
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Ahn H, Lee C, Nam BH, Kim EB, Caetano-Anolles K, Kim H. Selective pressure on the protein-coding genes of the pufferfish is correlated with phenotypic traits. Mar Genomics 2017; 37:182-186. [PMID: 29273445 DOI: 10.1016/j.margen.2017.11.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 11/04/2017] [Accepted: 11/29/2017] [Indexed: 11/28/2022]
Abstract
The pufferfish accumulates neurotoxic tetrodotoxin in its body and inflates by filling its stomach with water. These traits are unique to this species, and may be a result of adaptation post-divergence of Tetraodontidae. However, evolution of the protein-coding genes in the pufferfish has not yet been well elucidated. Detection of positive selection on these genes can help us understand the mechanisms associated with functional evolution. We downloaded well-annotated gene information of two pufferfish species, Takifugu rubripes and Tetraodon nigroviridis, from the public ENSEMBL database. In order to detect selective pressure on protein-coding sequences, we performed dN/dS estimation using codeml within the PAML software package. We selected one to one orthologous genes among seven fish species (Gasterosteus aculeatus, Oryzias latipes, Poecilia formosa, Takifugu rubripes, Tetraodon nigroviridis, and Xiphophorus maculatus). Results of dN/dS analysis on orthologous genes indicate that pufferfish showed high non-synonymous substitution rate for positively selected genes, and the evolutionary rate was faster during the diversification of two pufferfishes after divergence. Additionally, a candidate mechanism for regulation of neuro-toxicity of tetrodotoxin was identified from functional annotation of positively selected genes. These results support positive selection on protein-coding genes of the pufferfish with the acquisition of specific phenotypic traits.
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Affiliation(s)
- Hyeonju Ahn
- Department of Agricultural Biotechnology, Seoul National University, Seoul 151-742, Republic of Korea
| | - Chul Lee
- Interdisciplinary Program in Bioinformatics, Seoul National University, Seoul 151-742, Republic of Korea
| | - Bo-Hye Nam
- Biotechnology Research Division, National Fisheries Research & Development Institute, Busan 619-705, Republic of Korea
| | - Eun Bae Kim
- Department of Animal Life Science, Kangwon National University, Chuncheon 200-701, Republic of Korea
| | - Kelsey Caetano-Anolles
- Department of Agricultural Biotechnology, Seoul National University, Seoul 151-742, Republic of Korea
| | - Heebal Kim
- Department of Agricultural Biotechnology, Seoul National University, Seoul 151-742, Republic of Korea.
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Heide R, Bostock H, Ventzel L, Grafe P, Bergmans J, Fuglsang-Frederiksen A, Finnerup NB, Tankisi H. Axonal excitability changes and acute symptoms of oxaliplatin treatment: In vivo evidence for slowed sodium channel inactivation. Clin Neurophysiol 2017; 129:694-706. [PMID: 29233604 DOI: 10.1016/j.clinph.2017.11.015] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2016] [Revised: 10/16/2017] [Accepted: 11/05/2017] [Indexed: 01/28/2023]
Abstract
OBJECTIVE Neurotoxicity is the most frequent dose-limiting side effect of the anti-cancer agent oxaliplatin, but the mechanisms are not well understood. This study used nerve excitability testing to investigate the pathophysiology of the acute neurotoxicity. METHODS Questionnaires, quantitative sensory tests, nerve conduction studies and nerve excitability testing were undertaken in 12 patients with high-risk colorectal cancer treated with adjuvant oxaliplatin and in 16 sex- and age-matched healthy controls. Examinations were performed twice for patients: once within 3 days after oxaliplatin treatment (post-infusion examination) and once shortly before the following treatment (recovery examination). RESULTS The most frequent post-infusion symptoms were tingling paresthesias and cold allodynia. The most prominent nerve excitability change was decreased superexcitability of motor axons which correlated with the average intensity of abnormal sensations (Spearman Rho = 0.80, p < .01). The motor nerve excitability changes were well modeled by a slowing of sodium channel inactivation, and were proportional to dose/m2 with a half-life of about 10d. CONCLUSIONS Oxaliplatin induces reversible slowing of sodium channel inactivation in motor axons, and these changes are closely related to the reversible cold allodynia. However, further studies are required due to small sample size in this study. SIGNIFICANCE Nerve excitability data provide an index of sodium channel dysfunction: an objective biomarker of acute oxaliplatin neurotoxicity.
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Affiliation(s)
- Rikke Heide
- Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark; Danish Pain Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Hugh Bostock
- Institute of Neurology, Queen Square House, London, United Kingdom
| | - Lise Ventzel
- Department of Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark
| | - Peter Grafe
- Institute of Physiology, Ludwig-Maximilians University Munich, Munich, Germany
| | - Joseph Bergmans
- Laboratory of Clinical Neurophysiology, Faculty of Medicine, University of Louvain, Brussels, Belgium
| | | | - Nanna B Finnerup
- Danish Pain Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Hatice Tankisi
- Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark.
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Tomlinson SE, Howells J, Burke D. In vivo assessment of neurological channelopathies: Application of peripheral nerve excitability studies. Neuropharmacology 2017; 132:98-107. [PMID: 28476643 DOI: 10.1016/j.neuropharm.2017.04.045] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 04/19/2017] [Accepted: 04/29/2017] [Indexed: 12/14/2022]
Abstract
With the rapid evolution of understanding of neurological channelopathies comes a need for sensitive tools to evaluate patients in clinical practice. Neurological channelopathies with a single-gene basis can manifest as seizures, headache, ataxia, vertigo, confusion, weakness and neuropathic pain and it is likely that other genetic factors contribute to the phenotype of many of these disorders. Ion channel dysfunction can result in abnormal cell membrane excitability but utilisation of advanced neurophysiology techniques has lagged behind developments in clinical, genetic and imaging evaluation of channelopathies. However, momentum in the application of in vivo axonal excitability testing sees these tests emerging as valuable tools, with the capacity to provide sensitive and specific insights into the mechanism of disease. While single-channel function cannot be directly measured in vivo, evaluation of subjects with single-gene channelopathies has provided insights into the effects of mutation-related alterations of membrane excitability, as well as compensatory adaptive changes. By showing how ion channel dysfunction can affect axonal excitability in vivo, studies of the excitability of peripheral nerve axons complement in vitro analysis of single channel activity. The interpretation of results is enhanced by mathematical modelling of axonal function and insights provided by in vitro work. This article is part of the Special Issue entitled 'Channelopathies.'
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Affiliation(s)
- Susan E Tomlinson
- Sydney Medical School, University of Sydney, Sydney, Australia; Department of Neurology, St Vincent's Hospital, Sydney, Australia.
| | - James Howells
- Brain and Mind Centre, University of Sydney, Sydney, Australia
| | - David Burke
- Sydney Medical School, University of Sydney, Sydney, Australia; Department of Neurology, Royal Prince Alfred Hospital, Sydney, Australia
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Banzrai C, Nodera H, Okada R, Higashi S, Osaki Y, Kaji R. Modification of multiple ion channel functions in vivo by pharmacological inhibition: observation by threshold tracking and modeling. THE JOURNAL OF MEDICAL INVESTIGATION 2017; 64:30-38. [PMID: 28373625 DOI: 10.2152/jmi.64.30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Maintenance of axonal excitability relies on complex balance by multiple ion currents, but its evaluation is limited by in vitro single channel neurophysiological study on overall behavior. We sought to evaluate behaviors of multiple ion currents by pharmacological blockade. The threshold tracking technique was used to measure multiple excitability indices on tail sensory nerve of normal male mice before and after administration of either BaCl2 or ivabradine. Mathematical modeling was used to identify the interval changes of the channel parameters. After administration of BaCl2 and ivabradine, the following changes were present: greater threshold changes of both depolarizing and hyperpolarizing threshold electrotonus by both; additionally, reduced S2 accommodation, reduced late subexcitability and increased superexcitability by BaCl2, increased S3 accommodation by ivabradine. Mathematical modelling implied reduction of slow K+ conductance, along with reduction of H conductance (Ih) by BaCl2; and reduction of Ih while augmentation of K+ conductances by ivabradine. Pharmacological blockade of a selective ion channel may be compensated by other ion channels. Unintended effects by ion channel modification could be caused by secondary current alteration by multiple ion channels. J. Med. Invest. 64: 30-38, February, 2017.
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Knutsen HK, Alexander J, Barregård L, Bignami M, Brüschweiler B, Ceccatelli S, Cottrill B, Dinovi M, Edler L, Grasl-Kraupp B, Hogstrand C, Hoogenboom LR, Nebbia CS, Oswald IP, Rose M, Roudot AC, Schwerdtle T, Vleminckx C, Vollmer G, Wallace H, Arnich N, Benford D, Botana L, Viviani B, Arcella D, Binaglia M, Horvath Z, Steinkellner H, van Manen M, Petersen A. Risks for public health related to the presence of tetrodotoxin (TTX) and TTX analogues in marine bivalves and gastropods. EFSA J 2017; 15:e04752. [PMID: 32625458 PMCID: PMC7010203 DOI: 10.2903/j.efsa.2017.4752] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Tetrodotoxin (TTX) and its analogues are produced by marine bacteria and have been detected in marine bivalves and gastropods from European waters. The European Commission asked EFSA for a scientific opinion on the risks to public health related to the presence of TTX and TTX analogues in marine bivalves and gastropods. The Panel on Contaminants in the Food Chain reviewed the available literature but did not find support for the minimum lethal dose for humans of 2 mg, mentioned in various reviews. Some human case reports describe serious effects at a dose of 0.2 mg, corresponding to 4 μg/kg body weight (bw). However, the uncertainties on the actual exposure in the studies preclude their use for derivation of an acute reference dose (ARfD). Instead, a group ARfD of 0.25 μg/kg bw, applying to TTX and its analogues, was derived based on a TTX dose of 25 μg/kg bw at which no apathy was observed in an acute oral study with mice, applying a standard uncertainty factor of 100. Estimated relative potencies for analogues are lower than that of TTX but are associated with a high degree of uncertainty. Based on the occurrence data submitted to EFSA and reported consumption days only, average and P95 exposures of 0.00-0.09 and 0.00-0.03 μg/kg bw, respectively, were calculated. Using a large portion size of 400 g bivalves and P95 occurrence levels of TTX, with exception of oysters, the exposure was below the group ARfD in all consumer groups. A concentration below 44 μg TTX equivalents/kg shellfish meat, based on a large portion size of 400 g, was considered not to result in adverse effects in humans. Liquid chromatography with tandem mass spectroscopy (LC-MS/MS) methods are the most suitable for identification and quantification of TTX and its analogues, with LOQs between 1 and 25 μg/kg.
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Park SB, Kiernan MC, Vucic S. Axonal Excitability in Amyotrophic Lateral Sclerosis : Axonal Excitability in ALS. Neurotherapeutics 2017; 14:78-90. [PMID: 27878516 PMCID: PMC5233634 DOI: 10.1007/s13311-016-0492-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Axonal excitability testing provides in vivo assessment of axonal ion channel function and membrane potential. Excitability techniques have provided insights into the pathophysiological mechanisms underlying the development of neurodegeneration and clinical features of amyotrophic lateral sclerosis (ALS) and related neuromuscular disorders. Specifically, abnormalities of Na+ and K+ conductances contribute to development of membrane hyperexcitability in ALS, thereby leading to symptom generation of muscle cramps and fasciculations, in addition to promoting a neurodegenerative cascade via Ca2+-mediated processes. Modulation of axonal ion channel function in ALS has resulted in significant symptomatic improvement that has been accompanied by stabilization of axonal excitability parameters. Separately, axonal ion channel dysfunction evolves with disease progression and correlates with survival, thereby serving as a potential therapeutic biomarker in ALS. The present review provides an overview of axonal excitability techniques and the physiological mechanisms underlying membrane excitability, with a focus on the role of axonal ion channel dysfunction in motor neuron disease and related neuromuscular diseases.
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Affiliation(s)
- Susanna B Park
- Brain and Mind Centre, University of Sydney, Sydney, Australia
| | | | - Steve Vucic
- Westmead Clinical School, University of Sydney, Sydney, Australia.
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39
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Wevers NR, van Vught R, Wilschut KJ, Nicolas A, Chiang C, Lanz HL, Trietsch SJ, Joore J, Vulto P. High-throughput compound evaluation on 3D networks of neurons and glia in a microfluidic platform. Sci Rep 2016; 6:38856. [PMID: 27934939 PMCID: PMC5146966 DOI: 10.1038/srep38856] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 11/11/2016] [Indexed: 12/11/2022] Open
Abstract
With great advances in the field of in vitro brain modelling, the challenge is now to implement these technologies for development and evaluation of new drug candidates. Here we demonstrate a method for culturing three-dimensional networks of spontaneously active neurons and supporting glial cells in a microfluidic platform. The high-throughput nature of the platform in combination with its compatibility with all standard laboratory equipment allows for parallel evaluation of compound effects.
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Affiliation(s)
- Nienke R Wevers
- MIMETAS BV, J.H. Oortweg 19, 2333 CH, Leiden, the Netherlands.,Department of Molecular Cell Biology, Leiden University Medical Centre, Leiden, the Netherlands
| | - Remko van Vught
- MIMETAS BV, J.H. Oortweg 19, 2333 CH, Leiden, the Netherlands
| | | | - Arnaud Nicolas
- MIMETAS BV, J.H. Oortweg 19, 2333 CH, Leiden, the Netherlands.,Division of Analytical Biosciences, Leiden Academic Centre for Drug Research, Leiden University, the Netherlands
| | - Chiwan Chiang
- MIMETAS BV, J.H. Oortweg 19, 2333 CH, Leiden, the Netherlands
| | | | | | - Jos Joore
- MIMETAS BV, J.H. Oortweg 19, 2333 CH, Leiden, the Netherlands
| | - Paul Vulto
- MIMETAS BV, J.H. Oortweg 19, 2333 CH, Leiden, the Netherlands.,Division of Analytical Biosciences, Leiden Academic Centre for Drug Research, Leiden University, the Netherlands
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40
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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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41
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Koch S, Bierbrauer J, Haas K, Wolter S, Grosskreutz J, Luft FC, Spies CD, Fielitz J, Weber-Carstens S. Critical illness polyneuropathy in ICU patients is related to reduced motor nerve excitability caused by reduced sodium permeability. Intensive Care Med Exp 2016; 4:10. [PMID: 27207148 PMCID: PMC4875580 DOI: 10.1186/s40635-016-0083-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Accepted: 04/29/2016] [Indexed: 01/01/2023] Open
Abstract
Background Reduced motor and sensory nerve amplitudes in critical illness polyneuropathy (CIP) are characteristic features described in electrophysiological studies and due to dysfunction of voltage-gated sodium channels. Yet, faulty membrane depolarization as reported in various tissues of critically ill patients may cause reduced membrane excitability as well. The aim of this study was to compare the pathophysiological differences in motor nerve membrane polarization and voltage-gated sodium channel function between CIP patients and critically ill patients not developing CIP during their ICU stay (ICU controls). Methods ICU patients underwent electrophysiological nerve conduction studies and were categorized as either ICU controls or CIP patients. Subsequently, excitability parameters were recorded as current-threshold relationship, stimulus-response behavior, threshold electrotonus, and recovery of excitability from the abductor pollicis brevis following median nerve stimulation. Results Twenty-six critically ill patients were enrolled and categorized as 12 ICU controls and 14 CIP patients. When compared to 31 healthy subjects, the ICU controls exhibited signs of membrane depolarization as shown by reduced superexcitability (p = 0.003), depolarized threshold electrotonus (p = 0.007), increased current-threshold relationship (p = 0.03), and slightly prolonged strength-duration time constant. In contrast, the CIP patients displayed a significantly reduced strength-duration time constant (p < 0.0001), which indicates an increased inactivation of voltage-gated sodium channels. Conclusions Abnormal motor nerve membrane depolarization is a general finding in critically ill patients whereas voltage-gated sodium channel dysfunction is a characteristic of CIP patients. Electronic supplementary material The online version of this article (doi:10.1186/s40635-016-0083-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Susanne Koch
- Department of Anesthesiology and Intensive Care Medicine, Campus Virchow-Klinikum and Campus Charité Mitte, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany.
| | - Jeffrey Bierbrauer
- Klinik für diagnostische und interventionelle Radiologie und Nuklearmedizin, Klinikum Esslingen GmbH, Hirschlandstraße 97, 73730, Esslingen a.N, Germany
| | - Kurt Haas
- Department of Anesthesiology and Intensive Care Medicine, Campus Virchow-Klinikum and Campus Charité Mitte, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany
| | - Simone Wolter
- Department of Anesthesiology and Intensive Care Medicine, Campus Virchow-Klinikum and Campus Charité Mitte, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany
| | | | - Friedrich C Luft
- Experimental and Clinical Research Center, Charité - Universitätsmedizin Berlin, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Jena, Germany
| | - Claudia D Spies
- Department of Anesthesiology and Intensive Care Medicine, Campus Virchow-Klinikum and Campus Charité Mitte, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany
| | - Jens Fielitz
- Experimental and Clinical Research Center, Charité - Universitätsmedizin Berlin, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Jena, Germany.,Heart Center Brandenburg and Medical School Brandenburg (MHB), Bernau, Germany.,Berlin Institute of Health (BIH), Berlin, Germany
| | - Steffen Weber-Carstens
- Department of Anesthesiology and Intensive Care Medicine, Campus Virchow-Klinikum and Campus Charité Mitte, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany.,Berlin Institute of Health (BIH), Berlin, Germany
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Banzrai C, Nodera H, Kawarai T, Higashi S, Okada R, Mori A, Shimatani Y, Osaki Y, Kaji R. Impaired Axonal Na(+) Current by Hindlimb Unloading: Implication for Disuse Neuromuscular Atrophy. Front Physiol 2016; 7:36. [PMID: 26909041 PMCID: PMC4754663 DOI: 10.3389/fphys.2016.00036] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 01/26/2016] [Indexed: 12/12/2022] Open
Abstract
This study aimed to characterize the excitability changes in peripheral motor axons caused by hindlimb unloading (HLU), which is a model of disuse neuromuscular atrophy. HLU was performed in normal 8-week-old male mice by fixing the proximal tail by a clip connected to the top of the animal's cage for 3 weeks. Axonal excitability studies were performed by stimulating the sciatic nerve at the ankle and recording the compound muscle action potential (CMAP) from the foot. The amplitudes of the motor responses of the unloading group were 51% of the control amplitudes [2.2 ± 1.3 mV (HLU) vs. 4.3 ± 1.2 mV (Control), P = 0.03]. Multiple axonal excitability analysis showed that the unloading group had a smaller strength-duration time constant (SDTC) and late subexcitability (recovery cycle) than the controls [0.075 ± 0.01 (HLU) vs. 0.12 ± 0.01 (Control), P < 0.01; 5.4 ± 1.0 (HLU) vs. 10.0 ± 1.3 % (Control), P = 0.01, respectively]. Three weeks after releasing from HLU, the SDTC became comparable to the control range. Using a modeling study, the observed differences in the waveforms could be explained by reduced persistent Na+ currents along with parameters related to current leakage. Quantification of RNA of a SCA1A gene coding a voltage-gated Na+ channel tended to be decreased in the sciatic nerve in HLU. The present study suggested that axonal ion currents are altered in vivo by HLU. It is still undetermined whether the dysfunctional axonal ion currents have any pathogenicity on neuromuscular atrophy or are the results of neural plasticity by atrophy.
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Affiliation(s)
| | - Hiroyuki Nodera
- Department of Neurology, Tokushima University Tokushima, Japan
| | | | - Saki Higashi
- Department of Neurology, Tokushima University Tokushima, Japan
| | - Ryo Okada
- Department of Neurology, Tokushima University Tokushima, Japan
| | - Atsuko Mori
- Department of Neurology, Tokushima University Tokushima, Japan
| | | | - Yusuke Osaki
- Department of Neurology, Tokushima University Tokushima, Japan
| | - Ryuji Kaji
- Department of Neurology, Tokushima University Tokushima, Japan
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Tomlinson SE, Tan SV, Burke D, Labrum RW, Haworth A, Gibbons VS, Sweeney MG, Griggs RC, Kullmann DM, Bostock H, Hanna MG. In vivo impact of presynaptic calcium channel dysfunction on motor axons in episodic ataxia type 2. Brain 2016; 139:380-91. [PMID: 26912519 PMCID: PMC4795516 DOI: 10.1093/brain/awv380] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 10/22/2015] [Accepted: 10/26/2015] [Indexed: 11/13/2022] Open
Abstract
Ion channel dysfunction causes a range of neurological disorders by altering transmembrane ion fluxes, neuronal or muscle excitability, and neurotransmitter release. Genetic neuronal channelopathies affecting peripheral axons provide a unique opportunity to examine the impact of dysfunction of a single channel subtype in detail in vivo. Episodic ataxia type 2 is caused by mutations in CACNA1A, which encodes the pore-forming subunit of the neuronal voltage-gated calcium channel Cav2.1. In peripheral motor axons, this channel is highly expressed at the presynaptic neuromuscular junction where it contributes to action potential-evoked neurotransmitter release, but it is not expressed mid-axon or thought to contribute to action potential generation. Eight patients from five families with genetically confirmed episodic ataxia type 2 underwent neurophysiological assessment to determine whether axonal excitability was normal and, if not, whether changes could be explained by Cav2.1 dysfunction. New mutations in the CACNA1A gene were identified in two families. Nerve conduction studies were normal, but increased jitter in single-fibre EMG studies indicated unstable neuromuscular transmission in two patients. Excitability properties of median motor axons were compared with those in 30 age-matched healthy control subjects. All patients had similar excitability abnormalities, including a high electrical threshold and increased responses to hyperpolarizing (P < 0.00007) and depolarizing currents (P < 0.001) in threshold electrotonus. In the recovery cycle, refractoriness (P < 0.0002) and superexcitability (P < 0.006) were increased. Cav2.1 dysfunction in episodic ataxia type 2 thus has unexpected effects on axon excitability, which may reflect an indirect effect of abnormal calcium current fluxes during development.
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Affiliation(s)
- Susan E Tomlinson
- 1 Sydney Medical School, University of Sydney, Australia 2 Department of Neurology, St Vincent's Hospital, Sydney, Australia
| | - S Veronica Tan
- 3 Institute of Neurology, University College London and MRC Centre for Neuromuscular Disease, Queen Square, UK
| | - David Burke
- 1 Sydney Medical School, University of Sydney, Australia 4 Department of Neurology, Royal Prince Alfred Hospital, Sydney, Australia
| | - Robyn W Labrum
- 5 Neurogenetics Unit, National Hospital for Neurology, Queen Square, UK
| | - Andrea Haworth
- 5 Neurogenetics Unit, National Hospital for Neurology, Queen Square, UK
| | | | - Mary G Sweeney
- 5 Neurogenetics Unit, National Hospital for Neurology, Queen Square, UK
| | | | - Dimitri M Kullmann
- 3 Institute of Neurology, University College London and MRC Centre for Neuromuscular Disease, Queen Square, UK 5 Neurogenetics Unit, National Hospital for Neurology, Queen Square, UK
| | - Hugh Bostock
- 3 Institute of Neurology, University College London and MRC Centre for Neuromuscular Disease, Queen Square, UK
| | - Michael G Hanna
- 3 Institute of Neurology, University College London and MRC Centre for Neuromuscular Disease, Queen Square, UK 5 Neurogenetics Unit, National Hospital for Neurology, Queen Square, UK
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Tigerholm J, Petersson ME, Obreja O, Eberhardt E, Namer B, Weidner C, Lampert A, Carr RW, Schmelz M, Fransén E. C-fiber recovery cycle supernormality depends on ion concentration and ion channel permeability. Biophys J 2016; 108:1057-71. [PMID: 25762318 DOI: 10.1016/j.bpj.2014.12.034] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 11/30/2014] [Accepted: 12/17/2014] [Indexed: 12/20/2022] Open
Abstract
Following each action potential, C-fiber nociceptors undergo cyclical changes in excitability, including a period of superexcitability, before recovering their basal excitability state. The increase in superexcitability during this recovery cycle depends upon their immediate firing history of the axon, but also determines the instantaneous firing frequency that encodes pain intensity. To explore the mechanistic underpinnings of the recovery cycle phenomenon a biophysical model of a C-fiber has been developed. The model represents the spatial extent of the axon including its passive properties as well as ion channels and the Na/K-ATPase ion pump. Ionic concentrations were represented inside and outside the membrane. The model was able to replicate the typical transitions in excitability from subnormal to supernormal observed empirically following a conducted action potential. In the model, supernormality depended on the degree of conduction slowing which in turn depends upon the frequency of stimulation, in accordance with experimental findings. In particular, we show that activity-dependent conduction slowing is produced by the accumulation of intraaxonal sodium. We further show that the supernormal phase results from a reduced potassium current Kdr as a result of accumulation of periaxonal potassium in concert with a reduced influx of sodium through Nav1.7 relative to Nav1.8 current. This theoretical prediction was supported by data from an in vitro preparation of small rat dorsal root ganglion somata showing a reduction in the magnitude of tetrodotoxin-sensitive relative to tetrodotoxin -resistant whole cell current. Furthermore, our studies provide support for the role of depolarization in supernormality, as previously suggested, but we suggest that the basic mechanism depends on changes in ionic concentrations inside and outside the axon. The understanding of the mechanisms underlying repetitive discharges in recovery cycles may provide insight into mechanisms of spontaneous activity, which recently has been shown to correlate to a perceived level of pain.
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Affiliation(s)
- Jenny Tigerholm
- Department of Computational Biology, School of Computer Science and Communication, KTH Royal Institute of Technology, Stockholm, Sweden; Stockholm Brain Institute, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Marcus E Petersson
- Department of Computational Biology, School of Computer Science and Communication, KTH Royal Institute of Technology, Stockholm, Sweden; Stockholm Brain Institute, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Otilia Obreja
- Anaesthesiology, Universitaetsmedizin Mannheim, University of Heidelberg, Mannheim, Germany
| | - Esther Eberhardt
- Institute of Physiology and Pathophysiology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Barbara Namer
- Department of Anesthesiology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Christian Weidner
- Department of Anesthesiology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Angelika Lampert
- Institute of Physiology and Pathophysiology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany; Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | - Richard W Carr
- Anaesthesiology, Universitaetsmedizin Mannheim, University of Heidelberg, Mannheim, Germany
| | - Martin Schmelz
- Anaesthesiology, Universitaetsmedizin Mannheim, University of Heidelberg, Mannheim, Germany
| | - Erik Fransén
- Department of Computational Biology, School of Computer Science and Communication, KTH Royal Institute of Technology, Stockholm, Sweden; Stockholm Brain Institute, KTH Royal Institute of Technology, Stockholm, Sweden.
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Banzrai C, Nodera H, Higashi S, Okada R, Osaki Y, Mori A, Kaji R. Age-dependent effects on sensory axonal excitability in normal mice. Neurosci Lett 2016; 611:81-7. [DOI: 10.1016/j.neulet.2015.11.032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 11/09/2015] [Accepted: 11/20/2015] [Indexed: 01/07/2023]
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Kwai NCG, Arnold R, Poynten AM, Howells J, Kiernan MC, Lin CSY, Krishnan AV. In vivo evidence of reduced nodal and paranodal conductances in type 1 diabetes. Clin Neurophysiol 2015; 127:1700-1706. [PMID: 26725257 DOI: 10.1016/j.clinph.2015.11.047] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 11/13/2015] [Accepted: 11/29/2015] [Indexed: 12/28/2022]
Abstract
OBJECTIVES Diabetic neuropathy is a debilitating complication of diabetes. Animal models of type 1 diabetes (T1DM) suggest that functional and structural changes, specifically axo-glial dysjunction, may contribute to neuropathy development. The present study sought to examine and characterise early sensory axonal function in T1DM patients in the absence of clinical neuropathy. METHODS Thirty patients with T1DM (15M:15F) without neuropathy underwent median nerve sensory and motor axonal excitability studies to examine axonal function. A verified mathematical model of human motor and sensory axons was used to elucidate the underlying causes of observed alterations. RESULTS Compared to controls (NC), T1DM patients demonstrated significant axonal excitability abnormalities in sensory and motor axons. These included marked reductions in sensory and motor subexcitability during the recovery cycle (T1DM 7.9 ± 0.4:10.4 ± 0.6%, NC 10.4 ± 0.7:15.4 ± 1.2%, P<0.01) and during hyperpolarizing threshold electrotonus at 10-20 ms (T1DM -75.5 ± 0.8:-69.7 ± 0.8%, NC -78.4 ± 1:-72.7 ± 0.9%, P<0.01). Mathematical modelling demonstrated that these changes were due to reduced nodal Na(+) currents, nodal/paranodal K(+) conductances and Na(+)/K(+) pump dysfunction, consistent with axo-glial dysjunction as outlined in animal models of T1DM. CONCLUSIONS The study provided support for the occurrence of early changes in nodal and paranodal conductances in patients with T1DM. SIGNIFICANCE These data indicate that axonal excitability techniques may detect early changes in diabetic patients, providing a window of opportunity for prophylactic intervention in T1DM.
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Affiliation(s)
- Natalie C G Kwai
- Prince of Wales Clinical School, The University of New South Wales, Sydney, Australia
| | - Ria Arnold
- Department of Pharmacology and Physiology, The University of New South Wales, Sydney, Australia
| | - Ann M Poynten
- Department of Endocrinology, Prince of Wales Hospital, Sydney, Australia
| | - James Howells
- Brain and Mind Centre, University of Sydney and Royal Prince Alfred Hospital, Sydney, Australia
| | - Matthew C Kiernan
- Brain and Mind Centre, University of Sydney and Royal Prince Alfred Hospital, Sydney, Australia
| | - Cindy S-Y Lin
- Department of Pharmacology and Physiology, The University of New South Wales, Sydney, Australia
| | - Arun V Krishnan
- Prince of Wales Clinical School, The University of New South Wales, Sydney, Australia.
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Lai HJ, Chiang YW, Yang CC, Hsieh ST, Chao CC, Lee MJ, Kuo CC. The Temporal Profiles of Changes in Nerve Excitability Indices in Familial Amyloid Polyneuropathy. PLoS One 2015; 10:e0141935. [PMID: 26529114 PMCID: PMC4631457 DOI: 10.1371/journal.pone.0141935] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 10/14/2015] [Indexed: 01/19/2023] Open
Abstract
Familial amyloid polyneuropathy (FAP) caused by a mutation in transthyretin (TTR) gene is an autosomal dominant inherited disorder. The aim of this study is to explore the pathophysiological mechanism of FAP. We prospectively recruited 12 pauci-symptomatic carriers, 18 patients who harbor a TTR mutation, p.A97S, and two-age matched control groups. Data of nerve excitability test (NET) from ulnar motor and sensory axons were collected.NET study of ulnar motor axons of patients shows increased threshold and rheobase, reduced threshold elevation during hyperpolarizing threshold electrotonus (TE), and increased refractoriness. In sensory nerve studies, there are increased threshold reduction in depolarizing TE, lower slope of recovery and delayed time to overshoot after hyperpolarizing TE, increased refractoriness and superexcitability in recovery cycle. NET profiles obtained from the ulnar nerve of carriers show the increase of threshold and rheobase, whereas no significant threshold changes in hyperpolarizing TE and superexcitability. The regression models demonstrate that the increase of refractoriness and prolonged relative refractory period are correlated to the disease progression from carriers to patients. The marked increase of refractoriness at short-width stimulus suggests a defect in sodium current which may represent an early, pre-symptomatic pathophysiological change in TTR-FAP. Focal disruption of basal lamina and myelin may further increase the internodal capacity, manifested by the lower slope of recovery and delayed time to overshoot after hyperpolarization TE as well as the increase of superexcitability. NET could therefore make a pragmatic tool for monitoring disease progress from the very early stage of TTR-FAP.
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Affiliation(s)
- Hsing-Jung Lai
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
| | - Ya-Wen Chiang
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
| | - Chih-Chao Yang
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
| | - Sung-Tsang Hsieh
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
- Institute of Anatomy and Cell Biology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Chi-Chao Chao
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
| | - Ming-Jen Lee
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
- Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan
| | - Chung-Chin Kuo
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
- Institute of Physiology, National Taiwan University College of Medicine, Taipei, Taiwan
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Uncini A, Kuwabara S. Nodopathies of the peripheral nerve: an emerging concept. J Neurol Neurosurg Psychiatry 2015; 86:1186-95. [PMID: 25699569 DOI: 10.1136/jnnp-2014-310097] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 01/31/2015] [Indexed: 12/17/2022]
Abstract
Peripheral nerve diseases are traditionally classified as demyelinating or axonal. It has been recently proposed that microstructural changes restricted to the nodal/paranodal region may be the key to understanding the pathophysiology of antiganglioside antibody mediated neuropathies. We reviewed neuropathies with different aetiologies (dysimmune, inflammatory, ischaemic, nutritional, toxic) in which evidence from nerve conductions, excitability studies, pathology and animal models, indicate the involvement of the nodal region in the pathogenesis. For these neuropathies, the classification in demyelinating and axonal is inadequate or even misleading, we therefore propose a new category of nodopathy that has the following features: (1) it is characterised by a pathophysiological continuum from transitory nerve conduction block to axonal degeneration; (2) the conduction block may be due to paranodal myelin detachment, node lengthening, dysfunction or disruption of Na(+) channels, altered homeostasis of water and ions, or abnormal polarisation of the axolemma; (3) the conduction block may be promptly reversible without development of excessive temporal dispersion; (4) axonal degeneration, depending on the specific disorder and its severity, eventually follows the conduction block. The term nodopathy focuses to the site of primary nerve injury, avoids confusion with segmental demyelinating neuropathies and circumvents the apparent paradox that something axonal may be reversible and have a good prognosis.
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Affiliation(s)
- Antonino Uncini
- Department of Neuroscience, Imaging and Clinical Sciences, University "G d'Annunzio", Chieti-Pescara, Chieti, Italy
| | - Satoshi Kuwabara
- Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
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50
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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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