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Wu J, Wu J, Chen T, Cai J, Ren R. Protein aggregation and its affecting mechanisms in neurodegenerative diseases. Neurochem Int 2024; 180:105880. [PMID: 39396709 DOI: 10.1016/j.neuint.2024.105880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2024] [Revised: 10/09/2024] [Accepted: 10/11/2024] [Indexed: 10/15/2024]
Abstract
Protein aggregation serves as a critical pathological marker in a spectrum of neurodegenerative diseases (NDs), including the formation of amyloid β (Aβ) and Tau neurofibrillary tangles in Alzheimer's disease, as well as α-Synuclein (α-Syn) aggregates in Parkinson's disease, Parkinson's disease-related dementia (PDD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). A significant proportion of patients with amyotrophic lateral sclerosis (ALS) exhibit TDP-43 aggregates. Moreover, a confluence of brain protein pathologies, such as Aβ, Tau, α-Syn, and TDP-43, has been identified in individual NDs cases, highlighting the intricate interplay among these proteins that is garnering heightened scrutiny. Importantly, protein aggregation is modulated by an array of factors, with burgeoning evidence suggesting that it frequently results from perturbations in protein homeostasis, influenced by the cellular membrane milieu, metal ion concentrations, post-translational modifications, and genetic mutations. This review delves into the pathological underpinnings of protein aggregation across various NDs and elucidates the intercommunication among disparate proteins within the same disease context. Additionally, we examine the pathogenic mechanisms by which diverse factors impinge upon protein aggregation, offering fresh perspectives for the future therapeutic intervention of NDs.
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Affiliation(s)
- Junyun Wu
- Neuroscience Care Unit, Second Affiliated Hospital of Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, Zhejiang, 310009, China
| | - Jianan Wu
- Department of Neurosurgery, Second Affiliated Hospital of Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, Zhejiang, 310009, China
| | - Tao Chen
- Neuroscience Care Unit, Second Affiliated Hospital of Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, Zhejiang, 310009, China
| | - Jing Cai
- Neuroscience Care Unit, Second Affiliated Hospital of Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, Zhejiang, 310009, China.
| | - Reng Ren
- Neuroscience Care Unit, Second Affiliated Hospital of Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, Zhejiang, 310009, China.
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2
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Hernandez Silva JC, Pausic N, Marroquin Rivera A, Labonté B, Proulx CD. Chronic Social Defeat Stress Induces Pathway-Specific Adaptations at Lateral Habenula Neuronal Outputs. J Neurosci 2024; 44:e2082232024. [PMID: 39164106 PMCID: PMC11426382 DOI: 10.1523/jneurosci.2082-23.2024] [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: 11/14/2023] [Revised: 07/15/2024] [Accepted: 08/10/2024] [Indexed: 08/22/2024] Open
Abstract
The lateral habenula (LHb) has emerged as a pivotal brain region implicated in depression, displaying hyperactivity in human and animal models of depression. While the role of LHb efferents in depressive disorders has been acknowledged, the specific synaptic alterations remain elusive. Here, employing optogenetics, retrograde tracing, and ex vivo whole-cell patch-clamp techniques, we investigated synaptic transmission in male mice subjected to chronic social defeat stress (CSDS) at three major LHb neuronal outputs: the dorsal raphe nucleus (DRN), the ventral tegmental area (VTA), and the rostromedial tegmental nucleus (RMTg). Our findings uncovered distinct synaptic adaptations in LHb efferent circuits in response to CSDS. Specifically, CSDS induced in susceptible mice postsynaptic potentiation and postsynaptic depression at the DRN and VTA neurons, respectively, receiving excitatory inputs from the LHb, while CSDS altered presynaptic transmission at the LHb terminals in RMTg in both susceptible and resilient mice. Moreover, whole-cell recordings at projection-defined LHb neurons indicate decreased spontaneous activity in VTA-projecting LHb neurons, accompanied by an imbalance in excitatory-inhibitory inputs at the RMTg-projecting LHb neurons. Collectively, these novel findings underscore the circuit-specific alterations in LHb efferents following chronic social stress, shedding light on potential synaptic adaptations underlying stress-induced depressive-like states.
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Affiliation(s)
- Jose Cesar Hernandez Silva
- CERVO Brain Research Center, Department of Psychiatry and Neuroscience, Faculty of medicine, Université Laval, Quebec City, QC G1J 2G3, Canada
| | - Nikola Pausic
- CERVO Brain Research Center, Department of Psychiatry and Neuroscience, Faculty of medicine, Université Laval, Quebec City, QC G1J 2G3, Canada
| | - Arturo Marroquin Rivera
- CERVO Brain Research Center, Department of Psychiatry and Neuroscience, Faculty of medicine, Université Laval, Quebec City, QC G1J 2G3, Canada
| | - Benoît Labonté
- CERVO Brain Research Center, Department of Psychiatry and Neuroscience, Faculty of medicine, Université Laval, Quebec City, QC G1J 2G3, Canada
| | - Christophe D Proulx
- CERVO Brain Research Center, Department of Psychiatry and Neuroscience, Faculty of medicine, Université Laval, Quebec City, QC G1J 2G3, Canada
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Bär J, Fanutza T, Reimann CC, Seipold L, Grohe M, Bolter JR, Delfs F, Bucher M, Gee CE, Schweizer M, Saftig P, Mikhaylova M. Non-canonical function of ADAM10 in presynaptic plasticity. Cell Mol Life Sci 2024; 81:342. [PMID: 39123091 PMCID: PMC11335265 DOI: 10.1007/s00018-024-05327-8] [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: 02/20/2024] [Revised: 06/07/2024] [Accepted: 06/17/2024] [Indexed: 08/12/2024]
Abstract
A Disintegrin And Metalloproteinase 10 (ADAM10) plays a pivotal role in shaping neuronal networks by orchestrating the activity of numerous membrane proteins through the shedding of their extracellular domains. Despite its significance in the brain, the specific cellular localization of ADAM10 remains not well understood due to a lack of appropriate tools. Here, using a specific ADAM10 antibody suitable for immunostainings, we observed that ADAM10 is localized to presynapses and especially enriched at presynaptic vesicles of mossy fiber (MF)-CA3 synapses in the hippocampus. These synapses undergo pronounced frequency facilitation of neurotransmitter release, a process that play critical roles in information transfer and neural computation. We demonstrate, that in conditional ADAM10 knockout mice the ability of MF synapses to undergo this type of synaptic plasticity is greatly reduced. The loss of facilitation depends on the cytosolic domain of ADAM10 and association with the calcium sensor synaptotagmin 7 rather than ADAM10's proteolytic activity. Our findings unveil a new role of ADAM10 in the regulation of synaptic vesicle exocytosis.
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Affiliation(s)
- Julia Bär
- AG Optobiology, Institute of Biology, Humboldt Universität Zu Berlin, 10115, Berlin, Germany
- Guest Group, "Neuronal Protein Transport", Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany
| | - Tomas Fanutza
- AG Optobiology, Institute of Biology, Humboldt Universität Zu Berlin, 10115, Berlin, Germany
- Guest Group, "Neuronal Protein Transport", Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany
| | - Christopher C Reimann
- Guest Group, "Neuronal Protein Transport", Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany
| | - Lisa Seipold
- Biochemisches Institut, Christian Albrechts-Universität Kiel, 24098, Kiel, Germany
| | - Maja Grohe
- Biochemisches Institut, Christian Albrechts-Universität Kiel, 24098, Kiel, Germany
| | - Janike Rabea Bolter
- AG Optobiology, Institute of Biology, Humboldt Universität Zu Berlin, 10115, Berlin, Germany
| | - Flemming Delfs
- Guest Group, "Neuronal Protein Transport", Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany
| | - Michael Bucher
- Guest Group, "Neuronal Protein Transport", Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany
| | - Christine E Gee
- Department of Synaptic Physiology, Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany
| | - Michaela Schweizer
- Morphology and Electron Microscopy, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, ZMNH, 20251, Hamburg, Germany
| | - Paul Saftig
- Biochemisches Institut, Christian Albrechts-Universität Kiel, 24098, Kiel, Germany.
| | - Marina Mikhaylova
- AG Optobiology, Institute of Biology, Humboldt Universität Zu Berlin, 10115, Berlin, Germany.
- Guest Group, "Neuronal Protein Transport", Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251, Hamburg, Germany.
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Upshaw WC, Soileau LG, Storey NR, Perkinson KA, Luther PM, Spillers NJ, Robinson CL, Miller BC, Ahmadzadeh S, Viswanath O, Shekoohi S, Kaye AD. An extract of phase II and III trials on recent developments in managing neuropathic pain syndromes: diabetic peripheral neuropathy, trigeminal neuralgia, and postherpetic neuralgia. Expert Opin Emerg Drugs 2024; 29:103-112. [PMID: 38410863 DOI: 10.1080/14728214.2024.2323193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 02/21/2024] [Indexed: 02/28/2024]
Abstract
INTRODUCTION Neuropathic pain (NP) conditions involve lesions to the somatosensory nervous system leading to chronic and debilitating pain. Many patients suffering from NP utilize pharmacological treatments with various drugs that seek to reduce pathologic neuronal states. However, many of these drugs show poor efficacy as well as cause significant adverse effects. Because of this, there is a major need for the development of safer and more efficacious drugs to treat NP. AREAS COVERED In this review, we analyzed current treatments being developed for a variety of NP conditions. Specifically, we sought drugs in phase II/III clinical trials with indications for NP conditions. Various databases were searched including Google Scholar, PubMed, and clinicaltrials.gov. EXPERT OPINION All the mentioned targets for treatments of NP seem to be promising alternatives for existing treatments that often possess poor side effect profiles for patients. However, gene therapy potentially offers the unique ability to inject a plasmid containing growth factors leading to nerve growth and repair. Because of this, gene therapy appears to be the most intriguing new treatment for NP.
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Affiliation(s)
- William C Upshaw
- School of Medicine, Louisiana State University Health Sciences Center Shreveport, Shreveport, LA, USA
| | - Lenise G Soileau
- School of Medicine, Louisiana State University Health Sciences Center Shreveport, Shreveport, LA, USA
| | - Nicholas R Storey
- School of Medicine, Louisiana State University Health Sciences Center Shreveport, Shreveport, LA, USA
| | | | - Patrick M Luther
- School of Medicine, Louisiana State University Health Sciences Center Shreveport, Shreveport, LA, USA
| | - Noah J Spillers
- School of Medicine, Louisiana State University Health Sciences Center Shreveport, Shreveport, LA, USA
| | - Christopher L Robinson
- Beth Israel Deaconess Medical Center, Department of Anesthesiology, Critical Care, and Pain Medicine, Harvard Medical School, Boston, MA, USA
| | - Benjamin C Miller
- Department of Anesthesiology, Louisiana State University Health Sciences Center at Shreveport, Shreveport, LA, USA
| | - Shahab Ahmadzadeh
- Department of Anesthesiology, Louisiana State University Health Sciences Center at Shreveport, Shreveport, LA, USA
| | - Omar Viswanath
- Department of Anesthesiology, Louisiana State University Health Sciences Center at Shreveport, Shreveport, LA, USA
- Creighton University School of Medicine, Phoenix, AZ, USA
| | - Sahar Shekoohi
- Department of Anesthesiology, Louisiana State University Health Sciences Center at Shreveport, Shreveport, LA, USA
| | - Alan D Kaye
- Department of Anesthesiology, Louisiana State University Health Sciences Center at Shreveport, Shreveport, LA, USA
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Kim D, Lee CB, Park KK, Bang H, Truong PL, Lee J, Jeong BH, Kim H, Won SM, Kim DH, Lee D, Ko JH, Baac HW, Kim K, Park HJ. Highly Reliable 3D Channel Memory and Its Application in a Neuromorphic Sensory System for Hand Gesture Recognition. ACS NANO 2023; 17:24826-24840. [PMID: 38060577 DOI: 10.1021/acsnano.3c05493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2023]
Abstract
Brain-inspired neuromorphic computing systems, based on a crossbar array of two-terminal multilevel resistive random-access memory (RRAM), have attracted attention as promising technologies for processing large amounts of unstructured data. However, the low reliability and inferior conductance tunability of RRAM, caused by uncontrollable metal filament formation in the uneven switching medium, result in lower accuracy compared to the software neural network (SW-NN). In this work, we present a highly reliable CoOx-based multilevel RRAM with an optimized crystal size and density in the switching medium, providing a three-dimensional (3D) grain boundary (GB) network. This design enhances the reliability of the RRAM by improving the cycle-to-cycle endurance and device-to-device stability of the I-V characteristics with minimal variation. Furthermore, the designed 3D GB-channel RRAM (3D GB-RRAM) exhibits excellent conductance tunability, demonstrating high symmetricity (624), low nonlinearity (βLTP/βLTD ∼ 0.20/0.39), and a large dynamic range (Gmax/Gmin ∼ 31.1). The cyclic stability of long-term potentiation and depression also exceeds 100 cycles (105 voltage pulses), and the relative standard deviation of Gmax/Gmin is only 2.9%. Leveraging these superior reliability and performance attributes, we propose a neuromorphic sensory system for finger motion tracking and hand gesture recognition as a potential elemental technology for the metaverse. This system consists of a stretchable double-layered photoacoustic strain sensor and a crossbar array neural network. We perform training and recognition tasks on ultrasonic patterns associated with finger motion and hand gestures, attaining a recognition accuracy of 97.9% and 97.4%, comparable to that of SW-NN (99.8% and 98.7%).
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Affiliation(s)
- Dohyung Kim
- Department of Organic and Nano Engineering & Human-Tech Convergence Program, Hanyang University, Seoul 04763, Korea
| | - Cheong Beom Lee
- Department of Chemical Engineering, Hanyang University, Seoul 04763, Korea
| | - Kyu Kwan Park
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Korea
| | - Hyeonsu Bang
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Korea
| | - Phuoc Loc Truong
- Department of Mechanical Engineering, Gachon University, Gyeonggi 13120, Korea
| | - Jongmin Lee
- Department of Organic and Nano Engineering & Human-Tech Convergence Program, Hanyang University, Seoul 04763, Korea
| | - Bum Ho Jeong
- Department of Organic and Nano Engineering & Human-Tech Convergence Program, Hanyang University, Seoul 04763, Korea
| | - Hakjun Kim
- Department of Organic and Nano Engineering & Human-Tech Convergence Program, Hanyang University, Seoul 04763, Korea
| | - Sang Min Won
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Korea
| | - Do Hwan Kim
- Department of Chemical Engineering, Hanyang University, Seoul 04763, Korea
| | - Daeho Lee
- Department of Mechanical Engineering, Gachon University, Gyeonggi 13120, Korea
| | - Jong Hwan Ko
- College of Information and Communication Engineering, Sungkyunkwan University, Suwon 16419, Korea
| | - Hyoung Won Baac
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Korea
| | - Kyeounghak Kim
- Department of Chemical Engineering, Hanyang University, Seoul 04763, Korea
| | - Hui Joon Park
- Department of Organic and Nano Engineering & Human-Tech Convergence Program, Hanyang University, Seoul 04763, Korea
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Mariajoseph FP, Lai L, Moore J, Chandra R, Goldschlager T, Praeger AJ, Slater LA. Pathophysiology of Contrast-Induced Neurotoxicity: A Narrative Review of Possible Mechanisms. Eur Neurol 2023; 87:26-35. [PMID: 38118425 PMCID: PMC11003557 DOI: 10.1159/000535928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 12/18/2023] [Indexed: 12/22/2023]
Abstract
BACKGROUND Contrast-induced neurotoxicity (CIN) is an increasingly observed event following the administration of iodinated contrast. It presents as a spectrum of neurological symptoms that closely mimic ischaemic stroke, however, CIN remains a poorly understood clinical phenomenon. An appreciation of the underlying pathophysiological mechanisms is essential to improve clinical understanding and enhance decision-making. METHODS A broad literature search of Medline (1946 to December 2022) and Embase (1947 to December 2022) was conducted. Articles discussing the pathophysiology of CIN were reviewed. SUMMARY The pathogenesis of CIN appears to be multifactorial. A key step is likely blood-brain barrier (BBB) breakdown due to factors including ischaemic stroke, uncontrolled hypertension, and possibly contrast agents themselves, among others. This is followed by passage of contrast agents across the BBB, leading to chemotoxic sequelae on neural tissue. KEY MESSAGES This review provides a clinically oriented review on the pathophysiology of CIN to enhance knowledge and improve decision-making among clinicians.
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Affiliation(s)
- Frederick P. Mariajoseph
- Department of Neurosurgery, Monash Health, Clayton, VIC, Australia
- Department of Surgery, School of Clinical Sciences at Monash Health, Monash University, Melbourne, VIC, Australia
| | - Leon Lai
- Department of Neurosurgery, Monash Health, Clayton, VIC, Australia
- Department of Surgery, School of Clinical Sciences at Monash Health, Monash University, Melbourne, VIC, Australia
| | - Justin Moore
- Department of Neurosurgery, Monash Health, Clayton, VIC, Australia
- Department of Surgery, School of Clinical Sciences at Monash Health, Monash University, Melbourne, VIC, Australia
| | - Ronil Chandra
- Monash Imaging, Monash Health, Clayton, VIC, Australia
- Department of Radiology and Radiological Sciences, Monash University, Melbourne, VIC, Australia
| | - Tony Goldschlager
- Department of Neurosurgery, Monash Health, Clayton, VIC, Australia
- Department of Surgery, School of Clinical Sciences at Monash Health, Monash University, Melbourne, VIC, Australia
| | - Adrian J. Praeger
- Department of Neurosurgery, Monash Health, Clayton, VIC, Australia
- Department of Surgery, School of Clinical Sciences at Monash Health, Monash University, Melbourne, VIC, Australia
| | - Lee-Anne Slater
- Monash Imaging, Monash Health, Clayton, VIC, Australia
- Department of Radiology and Radiological Sciences, Monash University, Melbourne, VIC, Australia
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Labouesse MA, Torres-Herraez A, Chohan MO, Villarin JM, Greenwald J, Sun X, Zahran M, Tang A, Lam S, Veenstra-VanderWeele J, Lacefield CO, Bonaventura J, Michaelides M, Chan CS, Yizhar O, Kellendonk C. A non-canonical striatopallidal Go pathway that supports motor control. Nat Commun 2023; 14:6712. [PMID: 37872145 PMCID: PMC10593790 DOI: 10.1038/s41467-023-42288-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Accepted: 10/05/2023] [Indexed: 10/25/2023] Open
Abstract
In the classical model of the basal ganglia, direct pathway striatal projection neurons (dSPNs) send projections to the substantia nigra (SNr) and entopeduncular nucleus to regulate motor function. Recent studies have re-established that dSPNs also possess axon collaterals within the globus pallidus (GPe) (bridging collaterals), yet the significance of these collaterals for behavior is unknown. Here we use in vivo optical and chemogenetic tools combined with deep learning approaches in mice to dissect the roles of dSPN GPe collaterals in motor function. We find that dSPNs projecting to the SNr send synchronous motor-related information to the GPe via axon collaterals. Inhibition of native activity in dSPN GPe terminals impairs motor activity and function via regulation of Npas1 neurons. We propose a model by which dSPN GPe axon collaterals (striatopallidal Go pathway) act in concert with the canonical terminals in the SNr to support motor control by inhibiting Npas1 neurons.
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Affiliation(s)
- Marie A Labouesse
- Department of Psychiatry, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, 10032, USA.
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, 10032, USA.
- Department of Health, Sciences and Technology, ETH Zurich, 8092, Zurich, Switzerland.
- Neuroscience Center Zurich, ETH Zurich and University of Zurich, 8057, Zurich, Switzerland.
| | - Arturo Torres-Herraez
- Department of Psychiatry, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, 10032, USA
| | - Muhammad O Chohan
- Department of Psychiatry, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, 10032, USA
- Division of Child and Adolescent Psychiatry, New York State Psychiatric Institute, New York, NY, 10032, USA
| | - Joseph M Villarin
- Department of Psychiatry, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, 10032, USA
| | - Julia Greenwald
- Department of Psychiatry, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, 10032, USA
| | - Xiaoxiao Sun
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, 10032, USA
- Department of Biomedical Engineering, Columbia University, New York, NY, 10027, USA
| | - Mysarah Zahran
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, 10032, USA
- Barnard College, Columbia University, New York, NY, 10027, USA
| | - Alice Tang
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, 10032, USA
- Columbia College, Columbia University, New York, NY, 10027, USA
| | - Sherry Lam
- Biobehavioral Imaging and Molecular Neuropsychopharmacology Unit, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD, 21224, USA
| | - Jeremy Veenstra-VanderWeele
- Department of Psychiatry, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, 10032, USA
- Division of Child and Adolescent Psychiatry, New York State Psychiatric Institute, New York, NY, 10032, USA
| | - Clay O Lacefield
- Department of Psychiatry, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, 10032, USA
| | - Jordi Bonaventura
- Biobehavioral Imaging and Molecular Neuropsychopharmacology Unit, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD, 21224, USA
- Departament de Patologia i Terapèutica Experimental, Institut de Neurociències, L'Hospitalet de Llobregat, Universitat de Barcelona, Barcelona, Spain
| | - Michael Michaelides
- Biobehavioral Imaging and Molecular Neuropsychopharmacology Unit, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD, 21224, USA
- Department of Psychiatry & Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - C Savio Chan
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Ofer Yizhar
- Departments of Brain Sciences and Molecular Neuroscience, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Christoph Kellendonk
- Department of Psychiatry, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, 10032, USA.
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, 10032, USA.
- Department of Molecular Pharmacology & Therapeutics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, 10032, USA.
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Bitar A, Rosales R, Paulitsch M. Gradient-based feature-attribution explainability methods for spiking neural networks. Front Neurosci 2023; 17:1153999. [PMID: 37829721 PMCID: PMC10565802 DOI: 10.3389/fnins.2023.1153999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 09/01/2023] [Indexed: 10/14/2023] Open
Abstract
Introduction Spiking neural networks (SNNs) are a model of computation that mimics the behavior of biological neurons. SNNs process event data (spikes) and operate more sparsely than artificial neural networks (ANNs), resulting in ultra-low latency and small power consumption. This paper aims to adapt and evaluate gradient-based explainability methods for SNNs, which were originally developed for conventional ANNs. Methods The adapted methods aim to create input feature attribution maps for SNNs trained through backpropagation that process either event-based spiking data or real-valued data. The methods address the limitations of existing work on explainability methods for SNNs, such as poor scalability, limited to convolutional layers, requiring the training of another model, and providing maps of activation values instead of true attribution scores. The adapted methods are evaluated on classification tasks for both real-valued and spiking data, and the accuracy of the proposed methods is confirmed through perturbation experiments at the pixel and spike levels. Results and discussion The results reveal that gradient-based SNN attribution methods successfully identify highly contributing pixels and spikes with significantly less computation time than model-agnostic methods. Additionally, we observe that the chosen coding technique has a noticeable effect on the input features that will be most significant. These findings demonstrate the potential of gradient-based explainability methods for SNNs in improving our understanding of how these networks process information and contribute to the development of more efficient and accurate SNNs.
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Affiliation(s)
- Ammar Bitar
- Intel Labs, Munich, Germany
- Department of Knowledge Engineering, Maastricht University, Maastricht, Netherlands
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Drukarch B, Wilhelmus MMM. Thinking about the action potential: the nerve signal as a window to the physical principles guiding neuronal excitability. Front Cell Neurosci 2023; 17:1232020. [PMID: 37701723 PMCID: PMC10493309 DOI: 10.3389/fncel.2023.1232020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 07/17/2023] [Indexed: 09/14/2023] Open
Abstract
Ever since the work of Edgar Adrian, the neuronal action potential has been considered as an electric signal, modeled and interpreted using concepts and theories lent from electronic engineering. Accordingly, the electric action potential, as the prime manifestation of neuronal excitability, serving processing and reliable "long distance" communication of the information contained in the signal, was defined as a non-linear, self-propagating, regenerative, wave of electrical activity that travels along the surface of nerve cells. Thus, in the ground-breaking theory and mathematical model of Hodgkin and Huxley (HH), linking Nernst's treatment of the electrochemistry of semi-permeable membranes to the physical laws of electricity and Kelvin's cable theory, the electrical characteristics of the action potential are presented as the result of the depolarization-induced, voltage- and time-dependent opening and closure of ion channels in the membrane allowing the passive flow of charge, particularly in the form of Na+ and K+ -ions, into and out of the neuronal cytoplasm along the respective electrochemical ion gradient. In the model, which treats the membrane as a capacitor and ion channels as resistors, these changes in ionic conductance across the membrane cause a sudden and transient alteration of the transmembrane potential, i.e., the action potential, which is then carried forward and spreads over long(er) distances by means of both active and passive conduction dependent on local current flow by diffusion of Na+ ion in the neuronal cytoplasm. However, although highly successful in predicting and explaining many of the electric characteristics of the action potential, the HH model, nevertheless cannot accommodate the various non-electrical physical manifestations (mechanical, thermal and optical changes) that accompany action potential propagation, and for which there is ample experimental evidence. As such, the electrical conception of neuronal excitability appears to be incomplete and alternatives, aiming to improve, extend or even replace it, have been sought for. Commonly misunderstood as to their basic premises and the physical principles they are built on, and mistakenly perceived as a threat to the generally acknowledged explanatory power of the "classical" HH framework, these attempts to present a more complete picture of neuronal physiology, have met with fierce opposition from mainstream neuroscience and, as a consequence, currently remain underdeveloped and insufficiently tested. Here we present our perspective that this may be an unfortunate state of affairs as these different biophysics-informed approaches to incorporate also non-electrical signs of the action potential into the modeling and explanation of the nerve signal, in our view, are well suited to foster a new, more complete and better integrated understanding of the (multi)physical nature of neuronal excitability and signal transport and, hence, of neuronal function. In doing so, we will emphasize attempts to derive the different physical manifestations of the action potential from one common, macroscopic thermodynamics-based, framework treating the multiphysics of the nerve signal as the inevitable result of the collective material, i.e., physico-chemical, properties of the lipid bilayer neuronal membrane (in particular, the axolemma) and/or the so-called ectoplasm or membrane skeleton consisting of cytoskeletal protein polymers, in particular, actin fibrils. Potential consequences for our view of action potential physiology and role in neuronal function are identified and discussed.
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Affiliation(s)
| | - Micha M. M. Wilhelmus
- Amsterdam UMC, Vrije Universiteit Amsterdam, Department of Anatomy and Neurosciences, Amsterdam Neuroscience, Amsterdam, Netherlands
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10
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Huang WC, Peng Z, Murdock MH, Liu L, Mathys H, Davila-Velderrain J, Jiang X, Chen M, Ng AP, Kim T, Abdurrob F, Gao F, Bennett DA, Kellis M, Tsai LH. Lateral mammillary body neurons in mouse brain are disproportionately vulnerable in Alzheimer's disease. Sci Transl Med 2023; 15:eabq1019. [PMID: 37075128 PMCID: PMC10511020 DOI: 10.1126/scitranslmed.abq1019] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 03/31/2023] [Indexed: 04/21/2023]
Abstract
The neural circuits governing the induction and progression of neurodegeneration and memory impairment in Alzheimer's disease (AD) are incompletely understood. The mammillary body (MB), a subcortical node of the medial limbic circuit, is one of the first brain regions to exhibit amyloid deposition in the 5xFAD mouse model of AD. Amyloid burden in the MB correlates with pathological diagnosis of AD in human postmortem brain tissue. Whether and how MB neuronal circuitry contributes to neurodegeneration and memory deficits in AD are unknown. Using 5xFAD mice and postmortem MB samples from individuals with varying degrees of AD pathology, we identified two neuronal cell types in the MB harboring distinct electrophysiological properties and long-range projections: lateral neurons and medial neurons. lateral MB neurons harbored aberrant hyperactivity and exhibited early neurodegeneration in 5xFAD mice compared with lateral MB neurons in wild-type littermates. Inducing hyperactivity in lateral MB neurons in wild-type mice impaired performance on memory tasks, whereas attenuating aberrant hyperactivity in lateral MB neurons ameliorated memory deficits in 5xFAD mice. Our findings suggest that neurodegeneration may be a result of genetically distinct, projection-specific cellular dysfunction and that dysregulated lateral MB neurons may be causally linked to memory deficits in AD.
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Affiliation(s)
- Wen-Chin Huang
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
| | - Zhuyu Peng
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
| | - Mitchell H. Murdock
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
| | - Liwang Liu
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
| | - Hansruedi Mathys
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
- Broad Institute of MIT and Harvard; Cambridge, MA, 02139, USA
| | - Jose Davila-Velderrain
- Broad Institute of MIT and Harvard; Cambridge, MA, 02139, USA
- MIT Computer Science and Artificial Intelligence Laboratory; Cambridge, MA 02139, USA
| | - Xueqiao Jiang
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
| | - Maggie Chen
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
| | - Ayesha P. Ng
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
| | - TaeHyun Kim
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
| | - Fatema Abdurrob
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
| | - Fan Gao
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
| | - David A. Bennett
- Rush Alzheimer’s Disease Center, Rush University Medical Center; Chicago, IL 60612, USA
| | - Manolis Kellis
- Broad Institute of MIT and Harvard; Cambridge, MA, 02139, USA
- MIT Computer Science and Artificial Intelligence Laboratory; Cambridge, MA 02139, USA
| | - Li-Huei Tsai
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology; Cambridge, MA, 02139, USA
- Broad Institute of MIT and Harvard; Cambridge, MA, 02139, USA
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11
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Vyleta NP, Snyder JS. Enhanced excitability but mature action potential waveforms at mossy fiber terminals of young, adult-born hippocampal neurons in mice. Commun Biol 2023; 6:290. [PMID: 36934174 PMCID: PMC10024705 DOI: 10.1038/s42003-023-04678-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 03/07/2023] [Indexed: 03/20/2023] Open
Abstract
Adult-born granule neurons pass through immature critical periods where they display enhanced somatic excitability and afferent plasticity, which is believed to endow them with unique roles in hippocampal learning and memory. Using patch clamp recordings in mouse hippocampal slices, here we show that young neuron hyper-excitability is also observed at presynaptic mossy fiber terminals onto CA3 pyramidal neurons. However, action potential waveforms mature faster in the bouton than in the soma, suggesting rapid efferent functionality during immature stages.
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Affiliation(s)
- Nicholas P Vyleta
- Department of Psychology, Djavad Mowafaghian Center for Brain Health, University of British Columbia, Vancouver, BC, Canada
| | - Jason S Snyder
- Department of Psychology, Djavad Mowafaghian Center for Brain Health, University of British Columbia, Vancouver, BC, Canada.
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12
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Labouesse MA, Torres-Herraez A, Chohan MO, Villarin J, Greenwald J, Sun X, Zahran M, Tang A, Lam S, Veenstra-VanderWeele J, Lacefield C, Bonaventura J, Michaelides M, Chan CS, Yizhar O, Kellendonk C. A non-canonical striatopallidal "Go" pathway that supports motor control. RESEARCH SQUARE 2023:rs.3.rs-2524816. [PMID: 36798372 PMCID: PMC9934763 DOI: 10.21203/rs.3.rs-2524816/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
In the classical model of the basal ganglia, direct pathway striatal projection neurons (dSPNs) send projections to the substantia nigra (SNr) and entopeduncular nucleus to regulate motor function. Recent studies have re-established that dSPNs also possess "bridging" collaterals within the globus pallidus (GPe), yet the significance of these collaterals for behavior is unknown. Here we use in vivo optical and chemogenetic tools combined with deep learning approaches to dissect the roles of bridging collaterals in motor function. We find that dSPNs projecting to the SNr send synchronous motor-related information to the GPe via axon collaterals. Inhibition of native activity in dSPN GPe terminals impairs motor activity and function via regulation of pallidostriatal Npas1 neurons. We propose a model by which dSPN GPe collaterals ("striatopallidal Go pathway") act in concert with the canonical terminals in the SNr to support motor control by inhibiting Npas1 signals going back to the striatum.
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Affiliation(s)
- Marie A. Labouesse
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
- Current address: Department of Health, Sciences and Technology, ETH Zurich, and Zurich Neuroscience Center, 8057 Zurich, Switzerland
| | - Arturo Torres-Herraez
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
- Equal second-author contribution
| | - Muhammad O. Chohan
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
- Division of Child and Adolescent Psychiatry, New York State Psychiatric Institute, New York, NY 10032, USA
- Equal second-author contribution
| | - Joseph Villarin
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
- Equal second-author contribution
| | - Julia Greenwald
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Xiaoxiao Sun
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA
| | - Mysarah Zahran
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
- Barnard College, Columbia University, New York, NY 10027, USA
| | - Alice Tang
- Columbia College, Columbia University, New York, NY 10027, USA
| | - Sherry Lam
- Biobehavioral Imaging and Molecular Neuropsychopharmacology Unit, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD 21224, USA
| | - Jeremy Veenstra-VanderWeele
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
- Division of Child and Adolescent Psychiatry, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Clay Lacefield
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Jordi Bonaventura
- Biobehavioral Imaging and Molecular Neuropsychopharmacology Unit, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD 21224, USA
- Departament de Patologia i Terapèutica Experimental, Institut de Neurociències, Universitat de Barcelona, L’Hospitalet de Llobregat, Catalonia
| | - Michael Michaelides
- Biobehavioral Imaging and Molecular Neuropsychopharmacology Unit, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD 21224, USA
- Department of Psychiatry & Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore MD 21205, USA
| | - C. Savio Chan
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Ofer Yizhar
- Departments of Brain Sciences and Molecular Neuroscience, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Christoph Kellendonk
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
- Department of Pharmacology, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
- Lead contact: Christoph Kellendonk
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Lemercier CE, Garenne A, Poulletier de Gannes F, El Khoueiry C, Arnaud-Cormos D, Levêque P, Lagroye I, Percherancier Y, Lewis N. Comparative study between radiofrequency-induced and muscimol-induced inhibition of cultured networks of cortical neuron. PLoS One 2022; 17:e0268605. [PMID: 36044461 PMCID: PMC9432733 DOI: 10.1371/journal.pone.0268605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 08/17/2022] [Indexed: 11/30/2022] Open
Abstract
Previous studies have shown that spontaneously active cultured networks of cortical neuron grown planar microelectrode arrays are sensitive to radiofrequency (RF) fields and exhibit an inhibitory response more pronounced as the exposure time and power increase. To better understand the mechanism behind the observed effects, we aimed at identifying similarities and differences between the inhibitory effect of RF fields (continuous wave, 1800 MHz) to the γ-aminobutyric acid type A (GABAA) receptor agonist muscimol (MU). Inhibition of the network bursting activity in response to RF exposure became apparent at an SAR level of 28.6 W/kg and co-occurred with an elevation of the culture medium temperature of ~1°C. Exposure to RF fields preferentially inhibits bursting over spiking activity and exerts fewer constraints on neural network bursting synchrony, differentiating it from a pharmacological inhibition with MU. Network rebound excitation, a phenomenon relying on the intrinsic properties of cortical neurons, was observed following the removal of tonic hyperpolarization after washout of MU but not in response to cessation of RF exposure. This implies that hyperpolarization is not the main driving force mediating the inhibitory effects of RF fields. At the level of single neurons, network inhibition induced by MU and RF fields occurred with reduced action potential (AP) half-width. As changes in AP waveform strongly influence efficacy of synaptic transmission, the narrowing effect on AP seen under RF exposure might contribute to reducing network bursting activity. By pointing only to a partial overlap between the inhibitory hallmarks of these two forms of inhibition, our data suggest that the inhibitory mechanisms of the action of RF fields differ from the ones mediated by the activation of GABAA receptors.
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Affiliation(s)
- Clément E. Lemercier
- Laboratoire de l’Intégration du Matériau au Système, CNRS UMR 5218, University of Bordeaux, Talence, France
- Faculty of Medicine, Institute of Physiology, Department of Systems Neuroscience, Ruhr University Bochum, Bochum, Germany
- * E-mail: (CEL); (NL)
| | - André Garenne
- Laboratoire de l’Intégration du Matériau au Système, CNRS UMR 5218, University of Bordeaux, Talence, France
| | | | - Corinne El Khoueiry
- Laboratoire de l’Intégration du Matériau au Système, CNRS UMR 5218, University of Bordeaux, Talence, France
| | - Delia Arnaud-Cormos
- Univ. Limoges, CNRS, XLIM, UMR 7252, Limoges, France
- Institut Universitaire de France (IUF), Paris, France
| | | | - Isabelle Lagroye
- Laboratoire de l’Intégration du Matériau au Système, CNRS UMR 5218, University of Bordeaux, Talence, France
- Paris “Sciences et Lettres” Research University, Paris, France
| | - Yann Percherancier
- Laboratoire de l’Intégration du Matériau au Système, CNRS UMR 5218, University of Bordeaux, Talence, France
| | - Noëlle Lewis
- Laboratoire de l’Intégration du Matériau au Système, CNRS UMR 5218, University of Bordeaux, Talence, France
- * E-mail: (CEL); (NL)
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Ginebaugh SP, Badawi Y, Tarr TB, Meriney SD. Neuromuscular Active Zone Structure and Function in Healthy and Lambert-Eaton Myasthenic Syndrome States. Biomolecules 2022; 12:biom12060740. [PMID: 35740866 PMCID: PMC9221282 DOI: 10.3390/biom12060740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/16/2022] [Accepted: 05/18/2022] [Indexed: 12/02/2022] Open
Abstract
The mouse neuromuscular junction (NMJ) has long been used as a model synapse for the study of neurotransmission in both healthy and disease states of the NMJ. Neurotransmission from these neuromuscular nerve terminals occurs at highly organized structures called active zones (AZs). Within AZs, the relationships between the voltage-gated calcium channels and docked synaptic vesicles govern the probability of acetylcholine release during single action potentials, and the short-term plasticity characteristics during short, high frequency trains of action potentials. Understanding these relationships is important not only for healthy synapses, but also to better understand the pathophysiology of neuromuscular diseases. In particular, we are interested in Lambert-Eaton myasthenic syndrome (LEMS), an autoimmune disorder in which neurotransmitter release from the NMJ decreases, leading to severe muscle weakness. In LEMS, the reduced neurotransmission is traditionally thought to be caused by the antibody-mediated removal of presynaptic voltage-gated calcium channels. However, recent experimental data and AZ computer simulations have predicted that a disruption in the normally highly organized active zone structure, and perhaps autoantibodies to other presynaptic proteins, contribute significantly to pathological effects in the active zone and the characteristics of chemical transmitters.
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15
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Glycogen Synthase Kinase 3: Ion Channels, Plasticity, and Diseases. Int J Mol Sci 2022; 23:ijms23084413. [PMID: 35457230 PMCID: PMC9028019 DOI: 10.3390/ijms23084413] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/13/2022] [Accepted: 04/14/2022] [Indexed: 12/15/2022] Open
Abstract
Glycogen synthase kinase 3β (GSK3) is a multifaceted serine/threonine (S/T) kinase expressed in all eukaryotic cells. GSK3β is highly enriched in neurons in the central nervous system where it acts as a central hub for intracellular signaling downstream of receptors critical for neuronal function. Unlike other kinases, GSK3β is constitutively active, and its modulation mainly involves inhibition via upstream regulatory pathways rather than increased activation. Through an intricate converging signaling system, a fine-tuned balance of active and inactive GSK3β acts as a central point for the phosphorylation of numerous primed and unprimed substrates. Although the full range of molecular targets is still unknown, recent results show that voltage-gated ion channels are among the downstream targets of GSK3β. Here, we discuss the direct and indirect mechanisms by which GSK3β phosphorylates voltage-gated Na+ channels (Nav1.2 and Nav1.6) and voltage-gated K+ channels (Kv4 and Kv7) and their physiological effects on intrinsic excitability, neuronal plasticity, and behavior. We also present evidence for how unbalanced GSK3β activity can lead to maladaptive plasticity that ultimately renders neuronal circuitry more vulnerable, increasing the risk for developing neuropsychiatric disorders. In conclusion, GSK3β-dependent modulation of voltage-gated ion channels may serve as an important pharmacological target for neurotherapeutic development.
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16
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ATR regulates neuronal activity by modulating presynaptic firing. Nat Commun 2021; 12:4067. [PMID: 34210973 PMCID: PMC8249387 DOI: 10.1038/s41467-021-24217-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 06/01/2021] [Indexed: 02/06/2023] Open
Abstract
Ataxia Telangiectasia and Rad3-related (ATR) protein, as a key DNA damage response (DDR) regulator, plays an essential function in response to replication stress and controls cell viability. Hypomorphic mutations of ATR cause the human ATR-Seckel syndrome, characterized by microcephaly and intellectual disability, which however suggests a yet unknown role for ATR in non-dividing cells. Here we show that ATR deletion in postmitotic neurons does not compromise brain development and formation; rather it enhances intrinsic neuronal activity resulting in aberrant firing and an increased epileptiform activity, which increases the susceptibility of ataxia and epilepsy in mice. ATR deleted neurons exhibit hyper-excitability, associated with changes in action potential conformation and presynaptic vesicle accumulation, independent of DDR signaling. Mechanistically, ATR interacts with synaptotagmin 2 (SYT2) and, without ATR, SYT2 is highly upregulated and aberrantly translocated to excitatory neurons in the hippocampus, thereby conferring a hyper-excitability. This study identifies a physiological function of ATR, beyond its DDR role, in regulating neuronal activity.
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17
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Arsenault D, Tremblay C, Emond V, Calon F. Sex-dependent alterations in the physiology of entorhinal cortex neurons in old heterozygous 3xTg-AD mice. Biol Sex Differ 2020; 11:63. [PMID: 33198813 PMCID: PMC7667843 DOI: 10.1186/s13293-020-00337-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 10/15/2020] [Indexed: 01/29/2023] Open
Abstract
While the higher prevalence of Alzheimer’s disease (AD) in women is clear, studies suggest that biological sex may also influence AD pathogenesis. However, mechanisms behind these differences are not clear. To investigate physiological differences between sexes at the cellular level in the brain, we investigated the intrinsic and synaptic properties of entorhinal cortex neurons in heterozygous 3xTg-AD mice of both sexes at the age of 20 months. This brain region was selected because of its early association with AD symptoms. First, we found physiological differences between male and female non-transgenic mice, providing indirect evidence of axonal alterations in old females. Second, we observed a transgene-dependent elevation of the firing activity, post-burst afterhyperpolarization (AHP), and spontaneous excitatory postsynaptic current (EPSC) activity, without any effect of sex. Third, the passive properties and the hyperpolarization-activated current (Ih) were altered by transgene expression only in female mice, whereas the paired-pulse ratio (PPR) of evoked EPSC was changed only in males. Fourth, both sex and transgene expression were associated with changes in action potential properties. Consistent with previous work, higher levels of Aβ neuropathology were detected in 3xTg-AD females, whereas tau deposition was similar. In summary, our results support the idea that aging and AD neuropathology differentially alter the physiology of entorhinal cortex neurons in males and females.
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Affiliation(s)
- Dany Arsenault
- Faculty of Pharmacy, Université Laval, Quebec City, QC, Canada.,Neuroscience, Centre de Recherche du CHU de Québec (CHUQ), Quebec City, QC, Canada.,Physiotek, Quebec City, QC, Canada
| | - Cyntia Tremblay
- Neuroscience, Centre de Recherche du CHU de Québec (CHUQ), Quebec City, QC, Canada
| | - Vincent Emond
- Neuroscience, Centre de Recherche du CHU de Québec (CHUQ), Quebec City, QC, Canada
| | - Frédéric Calon
- Faculty of Pharmacy, Université Laval, Quebec City, QC, Canada. .,Neuroscience, Centre de Recherche du CHU de Québec (CHUQ), Quebec City, QC, Canada.
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18
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Derr JB, Tamayo J, Clark JA, Morales M, Mayther MF, Espinoza EM, Rybicka-Jasińska K, Vullev VI. Multifaceted aspects of charge transfer. Phys Chem Chem Phys 2020; 22:21583-21629. [PMID: 32785306 PMCID: PMC7544685 DOI: 10.1039/d0cp01556c] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Charge transfer and charge transport are by far among the most important processes for sustaining life on Earth and for making our modern ways of living possible. Involving multiple electron-transfer steps, photosynthesis and cellular respiration have been principally responsible for managing the energy flow in the biosphere of our planet since the Great Oxygen Event. It is impossible to imagine living organisms without charge transport mediated by ion channels, or electron and proton transfer mediated by redox enzymes. Concurrently, transfer and transport of electrons and holes drive the functionalities of electronic and photonic devices that are intricate for our lives. While fueling advances in engineering, charge-transfer science has established itself as an important independent field, originating from physical chemistry and chemical physics, focusing on paradigms from biology, and gaining momentum from solar-energy research. Here, we review the fundamental concepts of charge transfer, and outline its core role in a broad range of unrelated fields, such as medicine, environmental science, catalysis, electronics and photonics. The ubiquitous nature of dipoles, for example, sets demands on deepening the understanding of how localized electric fields affect charge transfer. Charge-transfer electrets, thus, prove important for advancing the field and for interfacing fundamental science with engineering. Synergy between the vastly different aspects of charge-transfer science sets the stage for the broad global impacts that the advances in this field have.
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Affiliation(s)
- James B Derr
- Department of Biochemistry, University of California, Riverside, CA 92521, USA.
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Distribution of VTA Glutamate and Dopamine Terminals, and their Significance in CA1 Neural Network Activity. Neuroscience 2020; 446:171-198. [PMID: 32652172 DOI: 10.1016/j.neuroscience.2020.06.045] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 06/29/2020] [Accepted: 06/30/2020] [Indexed: 01/05/2023]
Abstract
Reciprocal connection between the ventral tegmental area (VTA) and the hippocampus forms a loop that controls information entry into long-term memory. Compared with the widely studied VTA dopamine system, VTA glutamate terminals are anatomically dominant in the hippocampus and less understood. The current study employs anterograde and retrograde labeling of VTA dopamine and glutamate neurons to map the distribution of their terminals within the layers of the hippocampus. Also, functional tracing of VTA dopamine and glutamate projections to the hippocampus was performed by photostimulation of VTA cell bodies during CA1 extracellular voltage sampling in vivo. VTA dopamine terminals predominantly innervate the CA1 basal dendrite layer and modulate the firing rate of active putative neurons. In contrast, anatomical dominance of VTA glutamate terminals in the CA1 pyramidal cell and apical dendrite layers suggests the possible involvement of these terminals in excitability regulation. In support of these outcomes, photostimulation of VTA dopamine neurons increased the firing rate but not intrinsic excitability parameters for putative pyramidal units. Conversely, activation of VTA glutamate neurons increased CA1 network firing rate and burst rate. In addition, VTA glutamate inputs reduced the interspike and interburst intervals for putative CA1 neurons. Taken together, we deduced that layer-specific distribution of presynaptic dopamine and glutamate terminals in the hippocampus determinines VTA modulation (dopamine) or regulation (glutamate) of excitability in the CA1 neural network.
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Leão LKR, Bittencourt LO, Oliveira AC, Nascimento PC, Miranda GHN, Ferreira RO, Nabiça M, Dantas K, Dionizio A, Cartágenes S, Buzalaf MAR, Crespo-Lopez ME, Maia CSF, Lima RR. Long-Term Lead Exposure Since Adolescence Causes Proteomic and Morphological Alterations in the Cerebellum Associated with Motor Deficits in Adult Rats. Int J Mol Sci 2020; 21:ijms21103571. [PMID: 32443589 PMCID: PMC7279001 DOI: 10.3390/ijms21103571] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/11/2020] [Accepted: 03/16/2020] [Indexed: 11/16/2022] Open
Abstract
Lead (Pb) is an environmental contaminant that presents a high risk for human health. We aimed to investigate the possible alterations triggered by the exposure to Pb acetate for a long period in motor performance and the possible relationship with biochemical, proteomic and morphological alterations in the cerebellum of rats. Male Wistar rats were exposed for 55 days, at 50 mg/Kg of Pb acetate, and the control animals received distilled water. Open field (OF) and rotarod tests; biochemistry parameters (MDA and nitrite); staining/immunostaining of Purkinje cells (PC), mature neurons (MN), myelin sheath (MS) and synaptic vesicles (SYN) and proteomic profile were analyzed. Pb deposition on the cerebellum area and this study drove to exploratory and locomotion deficits and a decrease in the number of PC, MN, SYN and MS staining/immunostaining. The levels of MDA and nitrite remained unchanged. The proteomic profile showed alterations in proteins responsible for neurotransmitters release, as well as receptor function and second messengers signaling, and also proteins involved in the process of apoptosis. Thus, we conclude that the long-term exposure to low Pb dose promoted locomotion and histological tracings, associated with alterations in the process of cell signaling, as well as death by apoptosis.
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Affiliation(s)
- Luana Ketlen Reis Leão
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, Pará 66075-110, Brazil; (L.K.R.L.); (L.O.B.); (A.C.O.); (P.C.N.); (G.H.N.M.); (R.O.F.)
| | - Leonardo Oliveira Bittencourt
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, Pará 66075-110, Brazil; (L.K.R.L.); (L.O.B.); (A.C.O.); (P.C.N.); (G.H.N.M.); (R.O.F.)
| | - Ana Carolina Oliveira
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, Pará 66075-110, Brazil; (L.K.R.L.); (L.O.B.); (A.C.O.); (P.C.N.); (G.H.N.M.); (R.O.F.)
| | - Priscila Cunha Nascimento
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, Pará 66075-110, Brazil; (L.K.R.L.); (L.O.B.); (A.C.O.); (P.C.N.); (G.H.N.M.); (R.O.F.)
| | - Giza Hellen Nonato Miranda
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, Pará 66075-110, Brazil; (L.K.R.L.); (L.O.B.); (A.C.O.); (P.C.N.); (G.H.N.M.); (R.O.F.)
| | - Railson Oliveira Ferreira
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, Pará 66075-110, Brazil; (L.K.R.L.); (L.O.B.); (A.C.O.); (P.C.N.); (G.H.N.M.); (R.O.F.)
| | - Mariane Nabiça
- Laboratory of Applied Analytical Spectrometry, Institute of Exact and Natural Sciences, Federal University of Pará - Belém, Pará 66075-110, Brazil; (M.N.); (K.D.)
| | - Kelly Dantas
- Laboratory of Applied Analytical Spectrometry, Institute of Exact and Natural Sciences, Federal University of Pará - Belém, Pará 66075-110, Brazil; (M.N.); (K.D.)
| | - Aline Dionizio
- Department of Biological Sciences, Bauru Dental School, University of São Paulo - Bauru, São Paulo 17012-901, Brazil; (A.D.); (M.A.R.B.)
| | - Sabrina Cartágenes
- Laboratory of Inflammation and Behavior Pharmacology, Pharmacy Faculty, Institute of Health Sciences, Federal University of Pará - Belém, Pará 66075-110, Brazil; (S.C.); (C.S.F.M.)
| | - Marília Afonso Rabelo Buzalaf
- Department of Biological Sciences, Bauru Dental School, University of São Paulo - Bauru, São Paulo 17012-901, Brazil; (A.D.); (M.A.R.B.)
| | - Maria Elena Crespo-Lopez
- Laboratory of Molecular Pharmacology, Institute of Biological Sciences, Federal University of Pará - Belém, Pará 66075-110, Brazil;
| | - Cristiane S F Maia
- Laboratory of Inflammation and Behavior Pharmacology, Pharmacy Faculty, Institute of Health Sciences, Federal University of Pará - Belém, Pará 66075-110, Brazil; (S.C.); (C.S.F.M.)
| | - Rafael Rodrigues Lima
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, Pará 66075-110, Brazil; (L.K.R.L.); (L.O.B.); (A.C.O.); (P.C.N.); (G.H.N.M.); (R.O.F.)
- Correspondence: ; Tel.: +55-91-3201-7891
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21
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Satake S, Konishi S. Roscovitine differentially facilitates cerebellar glutamatergic and GABAergic neurotransmission by enhancing Ca v 2.1 channel-mediated multivesicular release. Eur J Neurosci 2020; 52:3002-3021. [PMID: 32383214 DOI: 10.1111/ejn.14771] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Revised: 04/22/2020] [Accepted: 05/01/2020] [Indexed: 11/29/2022]
Abstract
Synaptic vesicle exocytosis is triggered by Ca2+ influx through several subtypes of voltage-gated calcium channels in the presynaptic terminal. We previously reported that paired-pulse stimulation at brief intervals increases Cav 2.1 (P/Q-type) channel-mediated multivesicular release (MVR) at glutamatergic synapses between granule cells (GCs) and molecular layer interneurons (MLIs) in rat cerebellar slices. However, it has yet to be determined how Cav 2 channel subtypes take part in MVR in single axon terminal. This study therefore aimed at examining the effects of roscovitine on different types of cerebellar synapses that make contacts with Purkinje cells (PCs), because this compound has been shown to enhance Cav 2.1 channel-mediated MVR at GC-MLI synapses. Bath application of roscovitine profoundly increased the amplitude of excitatory postsynaptic currents (EPSCs) at GC-PC synapses by a presynaptic mechanism as previously observed at GC-MLI synapses, whereas it caused a marginal effect on climbing fiber-mediated EPSCs in PCs. At MLI-PC synapses, roscovitine increased both the amplitude and decay time of inhibitory postsynaptic currents (IPSCs) by enhancing multivesicular GABA release. When extracellular Ca2+ concentration ([Ca2+ ]e ) decreased, roscovitine became less effective in increasing GC-PC EPSCs. By contrast, roscovitine was able to augment MLI-PC IPSCs in the low [Ca2+ ]e . The Cav 2.1 channel blocker ω-agatoxin IVA suppressed the roscovitine-induced facilitatory actions on both GC-PC EPSCs and MLI-PC IPSCs. These results demonstrate that roscovitine enhances MVR at the GC-PC excitatory synapses in a manner dependent on the driving force of Cav 2.1 channel-mediated Ca2+ influx into the nerve terminal, while it also facilitates MLI-PC inhibitory transmission via Ca2+ -insensitive mechanisms.
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Affiliation(s)
- Shin'Ichiro Satake
- Department of Fundamental Neuroscience, National Institute for Physiological Sciences (NIPS), Okazaki, Japan.,School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Japan
| | - Shiro Konishi
- Department of Neurophysiology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Japan
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22
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da Silva DRF, Bittencourt LO, Aragão WAB, Nascimento PC, Leão LKR, Oliveira ACA, Crespo-López ME, Lima RR. Long-term exposure to lead reduces antioxidant capacity and triggers motor neurons degeneration and demyelination in spinal cord of adult rats. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 194:110358. [PMID: 32151863 DOI: 10.1016/j.ecoenv.2020.110358] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Revised: 02/17/2020] [Accepted: 02/18/2020] [Indexed: 06/10/2023]
Abstract
Lead is a toxic metal found in environment with great neurotoxic potential. The main effect is associated with impairments in hippocampus and cerebellum, driving to cognitive and motor dysfunctions, however, there is a lack of evidences about the effects over the spinal cord. In this way, we aimed to investigate in vivo the effects of long-term exposure to lead acetate in oxidative biochemistry and morphology of rats' spinal cord. For this, 36 male Wistar rats (Rattus norvegicus) were divided into the group exposed to 50 mg/kg of lead acetate and control group, which received only distilled water, both groups through intragastric gavage, for 55 days. After the exposure period, the animals were euthanized and the spinal cords were collected to perform the analyses of lead levels quantification, oxidative biochemistry evaluation by levels of malondialdehyde (MDA), nitrites and the antioxidant capacity against peroxyl radicals (ACAP). Besides, morphological evaluation with quantitative analysis of mature and motor neurons and reactivity to myelin basic protein (MBP). Our results showed high levels of lead in spinal cord after long-term exposure; there was a reduction on ACAP level; however, there was no difference observed in MDA and nitrite levels. Moreover, there was a reduction of mature and motor neurons in all three regions, and a reduction of immunolabeling of MBP in the thoracic and lumbar segments. Therefore, we conclude that long-term exposure to lead is able of increasing the levels of the metal in spinal cord, affecting the antioxidant capacity and inducing morphological impairments in spinal cord parenchyma. Our results also suggest that the tissue impairments triggered by lead may be resultant from others molecular mechanisms besides the oxidative stress.
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Affiliation(s)
- Dannilo Roberto Ferreira da Silva
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, State of Pará, Brazil
| | - Leonardo Oliveira Bittencourt
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, State of Pará, Brazil
| | - Walessa Alana Bragança Aragão
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, State of Pará, Brazil
| | - Priscila Cunha Nascimento
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, State of Pará, Brazil
| | - Luana Ketlen Reis Leão
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, State of Pará, Brazil
| | - Ana Carolina Alves Oliveira
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, State of Pará, Brazil
| | - Maria Elena Crespo-López
- Laboratory of Molecular Pharmacology, Institute of Biological Sciences, Federal University of Pará, Belém, State of Pará, Brazil
| | - Rafael Rodrigues Lima
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, State of Pará, Brazil.
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23
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Korshunov KS, Blakemore LJ, Bertram R, Trombley PQ. Spiking and Membrane Properties of Rat Olfactory Bulb Dopamine Neurons. Front Cell Neurosci 2020; 14:60. [PMID: 32265662 PMCID: PMC7100387 DOI: 10.3389/fncel.2020.00060] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 03/02/2020] [Indexed: 11/13/2022] Open
Abstract
The mammalian olfactory bulb (OB) has a vast population of dopamine (DA) neurons, whose function is to increase odor discrimination through mostly inhibitory synaptic mechanisms. However, it is not well understood whether there is more than one neuronal type of OB DA neuron, how these neurons respond to different stimuli, and the ionic mechanisms behind those responses. In this study, we used a transgenic rat line (hTH-GFP) to identify fluorescent OB DA neurons for recording via whole-cell electrophysiology. These neurons were grouped based on their localization in the glomerular layer ("Top" vs. "Bottom") with these largest and smallest neurons grouped by neuronal area ("Large" vs. "Small," in μm2). We found that some membrane properties could be distinguished based on a neuron's area, but not by its glomerular localization. All OB DA neurons produced a single action potential when receiving a sufficiently depolarizing stimulus, while some could also spike multiple times when receiving weaker stimuli, an activity that was more likely in Large than Small neurons. This single spiking activity is likely driven by the Na+ current, which showed a sensitivity to inactivation by depolarization and a relatively long time constant for the removal of inactivation. These recordings showed that Small neurons were more sensitive to inactivation of Na+ current at membrane potentials of -70 and -60 mV than Large neurons. The hyperpolarization-activated H-current (identified by voltage sags) was more pronounced in Small than Large DA neurons across hyperpolarized membrane potentials. Lastly, to mimic a more physiological stimulus, these neurons received ramp stimuli of various durations and current amplitudes. When stimulated with weaker/shallow ramps, the neurons needed less current to begin and end firing and they produced more action potentials at a slower frequency. These spiking properties were further analyzed between the four groups of neurons, and these analyses support the difference in spiking induced with current step stimuli. Thus, there may be more than one type of OB DA neuron, and these neurons' activities may support a possible role of being high-pass filters in the OB by allowing the transmission of stronger odor signals while inhibiting weaker ones.
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Affiliation(s)
- Kirill S Korshunov
- Program in Neuroscience, Florida State University, Tallahassee, FL, United States.,Department of Biological Science, Florida State University, Tallahassee, FL, United States
| | - Laura J Blakemore
- Program in Neuroscience, Florida State University, Tallahassee, FL, United States.,Department of Biological Science, Florida State University, Tallahassee, FL, United States
| | - Richard Bertram
- Program in Neuroscience, Florida State University, Tallahassee, FL, United States.,Department of Mathematics, Florida State University, Tallahassee, FL, United States
| | - Paul Q Trombley
- Program in Neuroscience, Florida State University, Tallahassee, FL, United States.,Department of Biological Science, Florida State University, Tallahassee, FL, United States
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Tran H, Ranta R, Le Cam S, Louis-Dorr V. Fast simulation of extracellular action potential signatures based on a morphological filtering approximation. J Comput Neurosci 2020; 48:27-46. [PMID: 31953614 DOI: 10.1007/s10827-019-00735-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 11/06/2019] [Accepted: 11/11/2019] [Indexed: 02/03/2023]
Abstract
Simulating extracellular recordings of neuronal populations is an important and challenging task both for understanding the nature and relationships between extracellular field potentials at different scales, and for the validation of methodological tools for signal analysis such as spike detection and sorting algorithms. Detailed neuronal multicompartmental models with active or passive compartments are commonly used in this objective. Although using such realistic NEURON models could lead to realistic extracellular potentials, it may require a high computational burden making the simulation of large populations difficult without a workstation. We propose in this paper a novel method to simulate extracellular potentials of firing neurons, taking into account the NEURON geometry and the relative positions of the electrodes. The simulator takes the form of a linear geometry based filter that models the shape of an action potential by taking into account its generation in the cell body / axon hillock and its propagation along the axon. The validity of the approach for different NEURON morphologies is assessed. We demonstrate that our method is able to reproduce realistic extracellular action potentials in a given range of axon/dendrites surface ratio, with a time-efficient computational burden.
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Affiliation(s)
- Harry Tran
- CNRS, CRAN, Université de Lorraine, F-54000, Nancy, France
| | - Radu Ranta
- CNRS, CRAN, Université de Lorraine, F-54000, Nancy, France.
| | - Steven Le Cam
- CNRS, CRAN, Université de Lorraine, F-54000, Nancy, France
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25
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Mosqueira M, Aykut G, Fink RHA. Mepivacaine reduces calcium transients in isolated murine ventricular cardiomyocytes. BMC Anesthesiol 2020; 20:10. [PMID: 31914932 PMCID: PMC6947945 DOI: 10.1186/s12871-019-0926-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 12/30/2019] [Indexed: 12/14/2022] Open
Abstract
Background The potential mechanism of mepivacaine’s myocardial depressant effect observed in papillary muscle has not yet been investigated at cellular level. Therefore, we evaluated mepivacaine’s effects on Ca2+ transient in isolated adult mouse cardiomyocytes. Methods Single ventricular myocytes were enzymatically isolated from wild-type C57Bl/6 mice and loaded with 10 μM fluorescent Ca2+ indicator Fluo-4-AM to record intracellular Ca2+ transients upon electrical stimulation. The mepivacaine effects at half-maximal inhibitory concentration (IC50) was determined on calibrated cardiomyocytes’ Ca2+ transients by non-parametric statistical analyses on biophysical parameters. Combination of mepivacaine with NCX blockers ORM-10103 or NiCl2 were used to test a possible mechanism to explain mepivacaine-induced Ca2+ transients’ reduction. Results A significant inhibition at mepivacaine’s IC50 (50 μM) on Ca2+ transients was measured in biophysical parameters such as peak (control: 528.6 ± 73.61 nM vs mepivacaine: 130.9 ± 15.63 nM; p < 0.05), peak area (control: 401.7 ± 63.09 nM*s vs mepivacaine: 72.14 ± 10.46 nM*s; p < 0.05), slope (control: 7699 ± 1110 nM/s vs mepivacaine: 1686 ± 226.6 nM/s; p < 0.05), time to peak (control: 107.9 ± 8.967 ms vs mepivacaine: 83.61 ± 7.650 ms; p < 0.05) and D50 (control: 457.1 ± 47.16 ms vs mepivacaine: 284.5 ± 22.71 ms; p < 0.05). Combination of mepivacaine with NCX blockers ORM-10103 or NiCl2 showed a significant increase in the baseline of [Ca2+] and arrhythmic activity upon electrical stimulation. Conclusion At cellular level, mepivacaine blocks Na+ channels, enhancing the reverse mode activity of NCX, leading to a significant reduction of Ca2+ transients. These results suggest a new mechanism for the mepivacaine-reduction contractility effect.
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Affiliation(s)
- Matias Mosqueira
- Cardio-Ventilatory Muscle Physiology Laboratory, Institute of Physiology and Pathophysiology, Heidelberg University Hospital, Im Neuenheimer Feld 326, 69120, Heidelberg, Germany.
| | - Güçlü Aykut
- Cardio-Ventilatory Muscle Physiology Laboratory, Institute of Physiology and Pathophysiology, Heidelberg University Hospital, Im Neuenheimer Feld 326, 69120, Heidelberg, Germany
| | - Rainer H A Fink
- Cardio-Ventilatory Muscle Physiology Laboratory, Institute of Physiology and Pathophysiology, Heidelberg University Hospital, Im Neuenheimer Feld 326, 69120, Heidelberg, Germany
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26
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Siddiqi MK, Malik S, Majid N, Alam P, Khan RH. Cytotoxic species in amyloid-associated diseases: Oligomers or mature fibrils. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2019; 118:333-369. [PMID: 31928731 DOI: 10.1016/bs.apcsb.2019.06.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Amyloid diseases especially, Alzheimer's disease (AD), is characterized by an imbalance between the production and clearance of amyloid-β (Aβ) species. Amyloidogenic proteins or peptides can transform structurally from monomers into β-stranded fibrils via multiple oligomeric states. Among various amyloid species, structured oligomers are proposed to be more toxic than fibrils; however, the identification of amyloid oligomers has been challenging due to their heterogeneous and metastable nature. Multiple techniques have recently helped in better understanding of oligomer's assembly details and structural properties. Moreover, some progress on elucidating the mechanisms of oligomer-triggered toxicity has been made. Based on the collection of current findings, there is growing consensus that control of toxic amyloid oligomers could be a valid approach to regulate amyloid-associated toxicity, which could advance development of new diagnostics and therapeutics for amyloid-related diseases. In this review, we have described the recent scenario of amyloid diseases with a great deal of information about the recent understanding of oligomers' assembly, structural properties, and toxicity. Also comprehensive details have been provided to differentiate the degree of toxicity associated with prefibrillar aggregates.
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Affiliation(s)
| | - Sadia Malik
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India
| | - Nabeela Majid
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India
| | - Parvez Alam
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India
| | - Rizwan Hasan Khan
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India
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27
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Saba L, Viscomi MT, Martini A, Caioli S, Mercuri NB, Guatteo E, Zona C. Modified age-dependent expression of NaV1.6 in an ALS model correlates with motor cortex excitability alterations. Neurobiol Dis 2019; 130:104532. [PMID: 31302244 DOI: 10.1016/j.nbd.2019.104532] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 06/28/2019] [Accepted: 07/10/2019] [Indexed: 12/13/2022] Open
Abstract
Cortical hyperexcitability is an early and intrinsic feature of Amyotrophic Lateral Sclerosis (ALS), but the mechanisms underlying this critical neuronal dysfunction are poorly understood. Recently, we have demonstrated that layer V pyramidal neurons (PNs) in the primary motor cortex (M1) of one-month old (P30) G93A ALS mice display an early hyperexcitability status compared to Control mice. In order to investigate the time-dependent evolution of the cortical excitability in the G93A ALS model, here we have performed an electrophysiological and immunohistochemical study at three different mouse ages. M1 PNs from 14-days old (P14) G93A mice have shown no excitability alterations, while M1 PNs from 3-months old (P90) G93A mice have shown a hypoexcitability status, compared to Control mice. These age-dependent cortical excitability dysfunctions correlate with a similar time-dependent trend of the persistent sodium current (INaP) amplitude alterations, suggesting that INaP may play a crucial role in the G93A cortical excitability aberrations. Specifically, immunohistochemistry experiments have indicated that the expression level of the NaV1.6 channel, one of the voltage-gated Na+ channels mainly distributed within the central nervous system, varies in G93A primary motor cortex during disease progression, according to the excitability and INaP alterations, but not in other cortical areas. Microfluorometry experiments, combined with electrophysiological recordings, have verified that P30 G93A PNs hyperexcitability is associated to a greater accumulation of intracellular calcium ([Ca2+]i) compared to Control PNs, and that this difference is still present when G93A and Control PNs fire action potentials at the same frequency. These results suggest that [Ca2+]i de-regulation in G93A PNs may contribute to neuronal demise and that the NaV1.6 channels could be a potential therapeutic target to ameliorate ALS disease progression.
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Affiliation(s)
- Luana Saba
- Department of Systems Medicine, University of Rome "Tor Vergata" via Montpellier 1, Rome 00133, Italy
| | - Maria Teresa Viscomi
- Università Cattolica del Sacro Cuore, Istituto di Istologia ed Embriologia, Fondazione Policlinico Universitario A. Gemelli, Largo F. Vito 1, Rome 00168, Italy
| | - Alessandro Martini
- IRCCS Fondazione Santa Lucia, via del Fosso di Fiorano 64, Rome 00143, Italy
| | - Silvia Caioli
- IRCCS Fondazione Santa Lucia, via del Fosso di Fiorano 64, Rome 00143, Italy
| | - Nicola Biagio Mercuri
- Department of Systems Medicine, University of Rome "Tor Vergata" via Montpellier 1, Rome 00133, Italy; IRCCS Fondazione Santa Lucia, via del Fosso di Fiorano 64, Rome 00143, Italy
| | - Ezia Guatteo
- IRCCS Fondazione Santa Lucia, via del Fosso di Fiorano 64, Rome 00143, Italy; Department of Motor Science and Wellness, University of Naples 'Parthenope', Via Medina 40, Naples 80133, Italy
| | - Cristina Zona
- Department of Systems Medicine, University of Rome "Tor Vergata" via Montpellier 1, Rome 00133, Italy; IRCCS Fondazione Santa Lucia, via del Fosso di Fiorano 64, Rome 00143, Italy.
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Burke KJ, Bender KJ. Modulation of Ion Channels in the Axon: Mechanisms and Function. Front Cell Neurosci 2019; 13:221. [PMID: 31156397 PMCID: PMC6533529 DOI: 10.3389/fncel.2019.00221] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 05/01/2019] [Indexed: 12/11/2022] Open
Abstract
The axon is responsible for integrating synaptic signals, generating action potentials (APs), propagating those APs to downstream synapses and converting them into patterns of neurotransmitter vesicle release. This process is mediated by a rich assortment of voltage-gated ion channels whose function can be affected on short and long time scales by activity. Moreover, neuromodulators control the activity of these proteins through G-protein coupled receptor signaling cascades. Here, we review cellular mechanisms and signaling pathways involved in axonal ion channel modulation and examine how changes to ion channel function affect AP initiation, AP propagation, and the release of neurotransmitter. We then examine how these mechanisms could modulate synaptic function by focusing on three key features of synaptic information transmission: synaptic strength, synaptic variability, and short-term plasticity. Viewing these cellular mechanisms of neuromodulation from a functional perspective may assist in extending these findings to theories of neural circuit function and its neuromodulation.
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Affiliation(s)
| | - Kevin J. Bender
- Neuroscience Graduate Program and Department of Neurology, Kavli Institute for Fundamental Neuroscience, Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, United States
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29
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Emmenegger V, Obien MEJ, Franke F, Hierlemann A. Technologies to Study Action Potential Propagation With a Focus on HD-MEAs. Front Cell Neurosci 2019; 13:159. [PMID: 31118887 PMCID: PMC6504789 DOI: 10.3389/fncel.2019.00159] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 04/08/2019] [Indexed: 12/26/2022] Open
Abstract
Axons convey information in neuronal circuits via reliable conduction of action potentials (APs) from the axon initial segment (AIS) to the presynaptic terminals. Recent experimental findings increasingly evidence that the axonal function is not limited to the simple transmission of APs. Advances in subcellular-resolution recording techniques have shown that axons display activity-dependent modulation in spike shape and conduction velocity, which influence synaptic strength and latency. We briefly review here, how recent methodological developments facilitate the understanding of the axon physiology. We included the three most common methods, i.e., genetically encoded voltage imaging (GEVI), subcellular patch-clamp and high-density microelectrode arrays (HD-MEAs). We then describe the potential of using HD-MEAs in studying axonal physiology in more detail. Due to their robustness, amenability to high-throughput and high spatiotemporal resolution, HD-MEAs can provide a direct functional electrical readout of single cells and cellular ensembles at subcellular resolution. HD-MEAs can, therefore, be employed in investigating axonal pathologies, the effects of large-scale genomic interventions (e.g., with RNAi or CRISPR) or in compound screenings. A combination of extracellular microelectrode arrays (MEAs), intracellular microelectrodes and optical imaging may potentially reveal yet unexplored repertoires of axonal functions.
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Affiliation(s)
- Vishalini Emmenegger
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
| | - Marie Engelene J. Obien
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
- MaxWell Biosystems AG, Basel, Switzerland
| | - Felix Franke
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
| | - Andreas Hierlemann
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
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30
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Abstract
Amyloid diseases are of major concern all over the world due to a number of factors including: (i) aging population, (ii) increasing life span and (iii) lack of effective pharmacotherapy options. The past decade has seen intense research in discovering disease-modifying multi-targeting small molecules as therapeutic options. In recent years, targeting the amyloid cascade has emerged as an attractive strategy to discover novel neurotherapeutics. Formation of amyloid species, with different degrees of solubility and neurotoxicity is associated with the gradual decline in cognition leading to dementia/cell dysfunction. Here, in this chapter, we have described the recent scenario of amyloid diseases with a great deal of information about the structural features of oligomers, protofibrils and fibrils. Also, comprehensive details have been provided to differentiate the degree of toxicity associated with prefibrillar aggregates. Moreover, a review of the technologies that aid characterisation of oligomer, protofibrils and fibrils as well as various inhibition strategies to overcome protein fibrillation are also discussed.
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Affiliation(s)
| | - Nabeela Majid
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, 202002, U.P., India
| | - Sadia Malik
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, 202002, U.P., India
| | - Parvez Alam
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, 202002, U.P., India
| | - Rizwan Hasan Khan
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, 202002, U.P., India.
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Awan H, Adve RS, Wallbridge N, Plummer C, Eckford AW. Communication and Information Theory of Single Action Potential Signals in Plants. IEEE Trans Nanobioscience 2018; 18:61-73. [PMID: 30442613 DOI: 10.1109/tnb.2018.2880924] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Many plants, such as Mimosa pudica (the "sensitive plant"), employ electrochemical signals known as action potentials (APs) for rapid intercellular communication. In this paper, we consider a reaction-diffusion model of individual AP signals to analyze APs from a communication- and information-theoretic perspective. We use concepts from molecular communication to explain the underlying process of information transfer in a plant for a single AP pulse that is shared with one or more receiver cells. We also use the chemical Langevin equation to accommodate the deterministic as well as stochastic component of the system. Finally, we present an information-theoretic analysis of single action potentials, obtaining achievable information rates for these signals. We show that, in general, the presence of an AP signal can increase the mutual information and information propagation speed among neighboring cells with receivers in different settings.
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Tovar KR, Bridges DC, Wu B, Randall C, Audouard M, Jang J, Hansma PK, Kosik KS. Action potential propagation recorded from single axonal arbors using multielectrode arrays. J Neurophysiol 2018; 120:306-320. [PMID: 29641308 DOI: 10.1152/jn.00659.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
We report the presence of co-occurring extracellular action potentials (eAPs) from cultured mouse hippocampal neurons among groups of planar electrodes on multielectrode arrays (MEAs). The invariant sequences of eAPs among coactive electrode groups, repeated co-occurrences, and short interelectrode latencies are consistent with action potential propagation in unmyelinated axons. Repeated eAP codetection by multiple electrodes was widespread in all our data records. Codetection of eAPs confirms they result from the same neuron and allows these eAPs to be isolated from all other spikes independently of spike sorting algorithms. We averaged co-occurring events and revealed additional electrodes with eAPs that would otherwise be below detection threshold. We used these eAP cohorts to explore the temperature sensitivity of action potential propagation and the relationship between voltage-gated sodium channel density and propagation velocity. The sequence of eAPs among coactive electrodes "fingerprints" neurons giving rise to these events and identifies them within neuronal ensembles. We used this property and the noninvasive nature of extracellular recording to monitor changes in excitability at multiple points in single axonal arbors simultaneously over several hours, demonstrating independence of axonal segments. Over several weeks, we recorded changes in interelectrode propagation latencies and ongoing changes in excitability in different regions of single axonal arbors. Our work illustrates how repeated eAP co-occurrences can be used to extract physiological data from single axons with low-density MEAs. However, repeated eAP co-occurrences lead to oversampling spikes from single neurons and thus can confound traditional spike-train analysis. NEW & NOTEWORTHY We studied action potential propagation in single axons using low-density multielectrode arrays. We unambiguously identified the neuronal sources of propagating action potentials and recorded extracellular action potentials from several positions within single axonal arbors. We found a surprisingly high density of axonal voltage-gated sodium channels responsible for a high propagation safety factor. Our experiments also demonstrate that excitability in different segments of single axons is regulated independently on timescales from hours to weeks.
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Affiliation(s)
- Kenneth R Tovar
- Neuroscience Research Institute, University of California , Santa Barbara, California
| | - Daniel C Bridges
- Neuroscience Research Institute, University of California , Santa Barbara, California.,Department of Physics, University of California , Santa Barbara, California
| | - Bian Wu
- Neuroscience Research Institute, University of California , Santa Barbara, California
| | - Connor Randall
- Department of Physics, University of California , Santa Barbara, California
| | - Morgane Audouard
- Neuroscience Research Institute, University of California , Santa Barbara, California.,Department of Molecular, Cellular and Developmental Biology, University of California , Santa Barbara, California
| | - Jiwon Jang
- Neuroscience Research Institute, University of California , Santa Barbara, California.,Department of Molecular, Cellular and Developmental Biology, University of California , Santa Barbara, California
| | - Paul K Hansma
- Neuroscience Research Institute, University of California , Santa Barbara, California.,Department of Physics, University of California , Santa Barbara, California
| | - Kenneth S Kosik
- Neuroscience Research Institute, University of California , Santa Barbara, California.,Department of Molecular, Cellular and Developmental Biology, University of California , Santa Barbara, California
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Zhang Y, Bucher D, Nadim F. Ionic mechanisms underlying history-dependence of conduction delay in an unmyelinated axon. eLife 2017; 6. [PMID: 28691900 PMCID: PMC5519330 DOI: 10.7554/elife.25382] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 07/06/2017] [Indexed: 11/13/2022] Open
Abstract
Axonal conduction velocity can change substantially during ongoing activity, thus modifying spike interval structures and, potentially, temporal coding. We used a biophysical model to unmask mechanisms underlying the history-dependence of conduction. The model replicates activity in the unmyelinated axon of the crustacean stomatogastric pyloric dilator neuron. At the timescale of a single burst, conduction delay has a non-monotonic relationship with instantaneous frequency, which depends on the gating rates of the fast voltage-gated Na+ current. At the slower timescale of minutes, the mean value and variability of conduction delay increase. These effects are because of hyperpolarization of the baseline membrane potential by the Na+/K+ pump, balanced by an h-current, both of which affect the gating of the Na+ current. We explore the mechanisms of history-dependence of conduction delay in axons and develop an empirical equation that accurately predicts this history-dependence, both in the model and in experimental measurements.
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Affiliation(s)
- Yang Zhang
- Department of Mathematical Sciences, New Jersey Institute of Technology, Newark, United States
| | - Dirk Bucher
- Federated Department of Biological Sciences, NJIT and Rutgers University, Newark, United States
| | - Farzan Nadim
- Department of Mathematical Sciences, New Jersey Institute of Technology, Newark, United States.,Federated Department of Biological Sciences, NJIT and Rutgers University, Newark, United States
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Daily NJ, Du ZW, Wakatsuki T. High-Throughput Phenotyping of Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes and Neurons Using Electric Field Stimulation and High-Speed Fluorescence Imaging. Assay Drug Dev Technol 2017; 15:178-188. [PMID: 28525289 DOI: 10.1089/adt.2017.781] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Electrophysiology of excitable cells, including muscle cells and neurons, has been measured by making direct contact with a single cell using a micropipette electrode. To increase the assay throughput, optical devices such as microscopes and microplate readers have been used to analyze electrophysiology of multiple cells. We have established a high-throughput (HTP) analysis of action potentials (APs) in highly enriched motor neurons and cardiomyocytes (CMs) that are differentiated from human induced pluripotent stem cells (iPSCs). A multichannel electric field stimulation (EFS) device enabled the ability to electrically stimulate cells and measure dynamic changes in APs of excitable cells ultra-rapidly (>100 data points per second) by imaging entire 96-well plates. We found that the activities of both neurons and CMs and their response to EFS and chemicals are readily discerned by our fluorescence imaging-based HTP phenotyping assay. The latest generation of calcium (Ca2+) indicator dyes, FLIPR Calcium 6 and Cal-520, with the HTP device enables physiological analysis of human iPSC-derived samples highlighting its potential application for understanding disease mechanisms and discovering new therapeutic treatments.
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Kalmbach BE, Gray R, Johnston D, Cook EP. Systems-based analysis of dendritic nonlinearities reveals temporal feature extraction in mouse L5 cortical neurons. J Neurophysiol 2017; 117:2188-2208. [PMID: 28250154 DOI: 10.1152/jn.00951.2016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2016] [Revised: 02/14/2017] [Accepted: 02/27/2017] [Indexed: 01/29/2023] Open
Abstract
What do dendritic nonlinearities tell a neuron about signals injected into the dendrite? Linear and nonlinear dendritic components affect how time-varying inputs are transformed into action potentials (APs), but the relative contribution of each component is unclear. We developed a novel systems-identification approach to isolate the nonlinear response of layer 5 pyramidal neuron dendrites in mouse prefrontal cortex in response to dendritic current injections. We then quantified the nonlinear component and its effect on the soma, using functional models composed of linear filters and static nonlinearities. Both noise and waveform current injections revealed linear and nonlinear components in the dendritic response. The nonlinear component consisted of fast Na+ spikes that varied in amplitude 10-fold in a single neuron. A functional model reproduced the timing and amplitude of the dendritic spikes and revealed that they were selective to a preferred input dynamic (~4.5 ms rise time). The selectivity of the dendritic spikes became wider in the presence of additive noise, which was also predicted by the functional model. A second functional model revealed that the dendritic spikes were weakly boosted before being linearly integrated at the soma. For both our noise and waveform dendritic input, somatic APs were dependent on the somatic integration of the stimulus, followed a subset of large dendritic spikes, and were selective to the same input dynamics preferred by the dendrites. Our results suggest that the amplitude of fast dendritic spikes conveys information about high-frequency features in the dendritic input, which is then combined with low-frequency somatic integration.NEW & NOTEWORTHY The nonlinear response of layer 5 mouse pyramidal dendrites was isolated with a novel systems-based approach. In response to dendritic current injections, the nonlinear component contained mostly fast, variable-amplitude, Na+ spikes. A functional model accounted for the timing and amplitude of the dendritic spikes and revealed that dendritic spikes are selective to a preferred input dynamic, which was verified experimentally. Thus, fast dendritic nonlinearities behave as high-frequency feature detectors that influence somatic action potentials.
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Affiliation(s)
- Brian E Kalmbach
- Center for Learning and Memory, Department of Neuroscience, The University of Texas at Austin, Austin, Texas; and
| | - Richard Gray
- Center for Learning and Memory, Department of Neuroscience, The University of Texas at Austin, Austin, Texas; and
| | - Daniel Johnston
- Center for Learning and Memory, Department of Neuroscience, The University of Texas at Austin, Austin, Texas; and
| | - Erik P Cook
- Centre for Mathematics in Bioscience and Medicine, Department of Physiology, McGill University, Montreal, Quebec, Canada
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Takano Y, Shirai O, Kitazumi Y, Kano K. Proposal of a new mechanism for the directional propagation of the action potential using a mimicking system. Phys Chem Chem Phys 2017; 19:5310-5317. [PMID: 28155939 DOI: 10.1039/c6cp07603c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A nerve conduction model is constructed by using some liquid-membrane cells that mimic the function of the K+ and Na+ channels. By imitating two types of Na+ channels (ligand-gated Na+ channels and voltage-gated Na+ channels), a new mechanism for the directional propagation of the action potential along the axon toward the axon terminal is proposed. When the nerve cell is excited by an external (outer) stimulus, it can be presumed that the ligand-gated channels work as power sources at the synapse to propagate the change in the membrane potential, and then the voltage-gated channels locally assist the propagation at each site of the axon (nodes of Ranvier).
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Affiliation(s)
- Y Takano
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
| | - O Shirai
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
| | - Y Kitazumi
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
| | - K Kano
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
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Andreasen M, Nedergaard S. Furosemide depresses the presynaptic fiber volley and modifies frequency-dependent axonal excitability in rat hippocampus. J Neurophysiol 2017; 117:1512-1523. [PMID: 28100655 DOI: 10.1152/jn.00704.2016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 01/17/2017] [Accepted: 01/17/2017] [Indexed: 11/22/2022] Open
Abstract
The loop diuretic furosemide is known to have anticonvulsant effects, believed to be exerted through blockade of glial Na+-K+-2Cl- cotransport causing altered volume regulation in brain tissue. The possibility that direct effects of furosemide on neuronal properties could also be involved is supported by previous observations, but such effects have not been thoroughly investigated. In the present study we show that furosemide has two opposing effects on stimulus-induced postsynaptic excitation in the nonepileptic rat hippocampal slice: 1) an enhancement of e-s coupling, which depended on intact GABAA transmission and was partially mimicked by selective blockade of K+-2Cl- cotransport, and 2) a decrement of field excitatory postsynaptic potentials. The balance between these effects varied, depending on the amount of synaptic drive. In addition, the compound action potential (fiber volley) recorded from the stimulated Schaffer collateral axons in stratum radiatum showed a progressive decrease during perfusion of furosemide. This effect was activity-independent, was mimicked by the stilbene derivative DIDS, and could be reproduced on fiber volleys in the alveus. Furosemide also reduced the initial enhancement of the fiber volley observed during trains of high-frequency stimulation (HFS). Results of hyperosmotic expansion of the extracellular volume, with 30 mM sucrose, indicated that both the induction and antagonism of the HFS-induced enhancement were independent of signaling via the extracellular space. Furosemide caused an increased decay of paired-pulse-induced supranormal axonal excitability, which was antagonized by ZD7288. We conclude that furosemide decreases axonal excitability and prevents HFS-induced hyperexcitability via mechanisms downstream of blockage of anion transport, which could include hyperpolarization of axonal membranes.NEW & NOTEWORTHY This study shows that the anion transporter antagonists furosemide and DIDS cause a marked decrease of axonal excitability in rat hippocampal CA1 region and prevent the induction of activity-dependent hyperexcitability in Schaffer collateral axons. The data are consistent with direct effects on axonal membrane properties. We also find that activity-dependent enhancement and depression of axonal excitability can be modified independently, suggesting that these events are governed by different underlying processes.
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Characterization of Specific Roles of Sodium Channel Subtypes in Regional Anesthesia. Reg Anesth Pain Med 2016; 40:599-604. [PMID: 26236999 DOI: 10.1097/aap.0000000000000294] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND AND OBJECTIVES Commonly used local anesthetics (eg, lidocaine) are nonselective in blocking sodium channel subtypes, potentially resulting in adverse events, such as prolonged muscle paralysis and unstable hemodynamics. Subtype-selective sodium channel block might avoid these unwanted adverse effects while preserving desirable anesthetic effects. The contributions of sodium channel subtypes in different components of regional anesthesia are unclear and this study assumed that selective sodium channel subtype block might produce selective nerve block. METHODS Sciatic nerve block was performed in mice with lidocaine (nonselective sodium channel blocker), tetrodotoxin (TTX, TTX-sensitive sodium channel blocker), and A-803467 (selective Nav1.8 subtype blocker). Tactile sensory, pinprick, and thermal sensory block as well as motor block were evaluated after injection of study drugs. Median effective concentration (EC50) of lidocaine, TTX, and A-803467 as well as their blocking durations were determined. RESULTS Lidocaine produced regional anesthetic effects including tactile, pinprick, and thermal sensory block as well as motor block, with EC50 [mean, 95% confidence intervals (CIs)] of 4.4 (3.7-5.2), 9.4 (8.0-10.9), 5.2 (4.3-6.2), and 3.7 (3.3-4.2) mmol/L, respectively. Tetrodotoxin produced tactile sensory block and motor block with EC50 (mean, 95% CIs) of 7.7 (6.0-11.0) and 8.3 (7.4-9.8) μmol/L, respectively; whereas A-803467 produced tactile sensory block only, with EC50 (mean, 95% CIs) of 12.6 (11.7-15.6) μmol/L. CONCLUSIONS Sodium channel subtype selective blockers could induce selective nerve blocks. Tetrodotoxin-sensitive sodium channel subtypes contribute to low-threshold sensory block (eg, tactile) and motor block. Unexpectedly, selective Nav1.8 subtype block induced low-threshold sensory block rather than nociceptive or motor block.
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Takano Y, Shirai O, Kitazumi Y, Kano K. Propagation of the change in the membrane potential using a biocell-model. Phys Chem Chem Phys 2016; 18:12689-95. [PMID: 27094735 DOI: 10.1039/c5cp07446k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new model system of nerve conduction, which has two sites (the potential-sending and the potential-receiving sites) was constructed by the use of some liquid-membrane cells which mimic the function of the K(+) and Na(+) channels. The model system setup was such that the membrane potential of the K(+)-channel cell (resting potential) was different from that of the Na(+)-channel cell (action potential). Initially, the K(+)-channel cell at the potential-sending site was connected to that at the potential-receiving site. After switching from the K(+)-channel cell to the Na(+)-channel cell at the potential-sending site, the membrane potential of the K(+)-channel cell at the potential-receiving site began to vary with the generation of the circulating current. By placing several K(+)-channel cells in parallel at the potential-receiving site, the propagation mechanism of the action potential was interpreted and the influence of the resistor and the capacitor on the propagation was evaluated.
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Affiliation(s)
- Yoshinari Takano
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
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40
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Lewandowska MK, Radivojević M, Jäckel D, Müller J, Hierlemann AR. Cortical Axons, Isolated in Channels, Display Activity-Dependent Signal Modulation as a Result of Targeted Stimulation. Front Neurosci 2016; 10:83. [PMID: 27013945 PMCID: PMC4779934 DOI: 10.3389/fnins.2016.00083] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/19/2016] [Indexed: 12/01/2022] Open
Abstract
Mammalian cortical axons are extremely thin processes that are difficult to study as a result of their small diameter: they are too narrow to patch while intact, and super-resolution microscopy is needed to resolve single axons. We present a method for studying axonal physiology by pairing a high-density microelectrode array with a microfluidic axonal isolation device, and use it to study activity-dependent modulation of axonal signal propagation evoked by stimulation near the soma. Up to three axonal branches from a single neuron, isolated in different channels, were recorded from simultaneously using 10-20 electrodes per channel. The axonal channels amplified spikes such that propagations of individual signals along tens of electrodes could easily be discerned with high signal to noise. Stimulation from 10 up to 160 Hz demonstrated similar qualitative results from all of the cells studied: extracellular action potential characteristics changed drastically in response to stimulation. Spike height decreased, spike width increased, and latency increased, as a result of reduced propagation velocity, as the number of stimulations and the stimulation frequencies increased. Quantitatively, the strength of these changes manifested itself differently in cells at different frequencies of stimulation. Some cells' signal fidelity fell to 80% already at 10 Hz, while others maintained 80% signal fidelity at 80 Hz. Differences in modulation by axonal branches of the same cell were also seen for different stimulation frequencies, starting at 10 Hz. Potassium ion concentration changes altered the behavior of the cells causing propagation failures at lower concentrations and improving signal fidelity at higher concentrations.
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Affiliation(s)
- Marta K Lewandowska
- Bio Engineering Laboratory, Department of Biosystems Science and Engineering, ETH Zürich Basel, Switzerland
| | - Miloš Radivojević
- Bio Engineering Laboratory, Department of Biosystems Science and Engineering, ETH Zürich Basel, Switzerland
| | - David Jäckel
- Bio Engineering Laboratory, Department of Biosystems Science and Engineering, ETH Zürich Basel, Switzerland
| | - Jan Müller
- Bio Engineering Laboratory, Department of Biosystems Science and Engineering, ETH Zürich Basel, Switzerland
| | - Andreas R Hierlemann
- Bio Engineering Laboratory, Department of Biosystems Science and Engineering, ETH Zürich Basel, Switzerland
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Freeman SA, Desmazières A, Fricker D, Lubetzki C, Sol-Foulon N. Mechanisms of sodium channel clustering and its influence on axonal impulse conduction. Cell Mol Life Sci 2016; 73:723-35. [PMID: 26514731 PMCID: PMC4735253 DOI: 10.1007/s00018-015-2081-1] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 10/21/2015] [Accepted: 10/22/2015] [Indexed: 12/16/2022]
Abstract
The efficient propagation of action potentials along nervous fibers is necessary for animals to interact with the environment with timeliness and precision. Myelination of axons is an essential step to ensure fast action potential propagation by saltatory conduction, a process that requires highly concentrated voltage-gated sodium channels at the nodes of Ranvier. Recent studies suggest that the clustering of sodium channels can influence axonal impulse conduction in both myelinated and unmyelinated fibers, which could have major implications in disease, particularly demyelinating pathology. This comprehensive review summarizes the mechanisms governing the clustering of sodium channels at the peripheral and central nervous system nodes and the specific roles of their clustering in influencing action potential conduction. We further highlight the classical biophysical parameters implicated in conduction timing, followed by a detailed discussion on how sodium channel clustering along unmyelinated axons can impact axonal impulse conduction in both physiological and pathological contexts.
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Affiliation(s)
- Sean A Freeman
- ICM-GHU Pitié-Salpêtrière, Sorbonne Universités UPMC Univ Paris 06, UMR_S 1127, 75013, Paris, France.
- Inserm U1127, 75013, Paris, France.
- CNRS UMR7225, 75013, Paris, France.
| | - Anne Desmazières
- ICM-GHU Pitié-Salpêtrière, Sorbonne Universités UPMC Univ Paris 06, UMR_S 1127, 75013, Paris, France.
- Inserm U1127, 75013, Paris, France.
- CNRS UMR7225, 75013, Paris, France.
| | - Desdemona Fricker
- ICM-GHU Pitié-Salpêtrière, Sorbonne Universités UPMC Univ Paris 06, UMR_S 1127, 75013, Paris, France.
- Inserm U1127, 75013, Paris, France.
- CNRS UMR7225, 75013, Paris, France.
| | - Catherine Lubetzki
- ICM-GHU Pitié-Salpêtrière, Sorbonne Universités UPMC Univ Paris 06, UMR_S 1127, 75013, Paris, France.
- Inserm U1127, 75013, Paris, France.
- CNRS UMR7225, 75013, Paris, France.
- Assistance Publique-Hôpitaux de Paris, Hôpital Pitié-Salpêtrière, Paris, France.
| | - Nathalie Sol-Foulon
- ICM-GHU Pitié-Salpêtrière, Sorbonne Universités UPMC Univ Paris 06, UMR_S 1127, 75013, Paris, France.
- Inserm U1127, 75013, Paris, France.
- CNRS UMR7225, 75013, Paris, France.
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43
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Kushida Y, Shirai O, Takano Y, Kitazumi Y, Kano K. Influence of the Circulating Current on the Propagation of the Change in Membrane Potential. ANAL SCI 2015; 31:677-83. [PMID: 26165291 DOI: 10.2116/analsci.31.677] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The propagation of the change in potential differences across liquid membranes from the potential-sending cell to the potential-receiving cell was investigated by use of a system combined with three liquid membrane cells, which were composed of two aqueous phases and a 1,2-dichloroethane solution phase. The ionic composition of one potential-sending cell (S) was identical to that of the receiving cell (Rec), and that of another potential-sending cell (Ap) was different from that of the Rec. When the connection of cell Rec was switched from cell S to cell Ap, the change in the membrane potential was caused by the circulating current. The greater the ratio of the interfacial area of the membrane of cell Ap to that of cell Rec, the faster the change in the membrane potential propagated from cell Ap to cell Rec.
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Affiliation(s)
- Yuki Kushida
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University
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Kushida Y, Shirai O, Kitazumi Y, Kano K. Influence of Charging Current and Potential Drop on the Propagation of the Change in the Membrane Potential. ELECTROANAL 2014. [DOI: 10.1002/elan.201400195] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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45
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Rodríguez-Molina V, Patiño J, Vargas Y, Sánchez-Jaramillo E, Joseph-Bravo P, Charli JL. TRH regulates action potential shape in cerebral cortex pyramidal neurons. Brain Res 2014; 1571:1-11. [PMID: 24842001 DOI: 10.1016/j.brainres.2014.05.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 05/03/2014] [Accepted: 05/08/2014] [Indexed: 11/28/2022]
Abstract
Thyrotropin releasing hormone (TRH) is a neuropeptide with a wide neural distribution and a variety of functions. It modulates neuronal electrophysiological properties, including resting membrane potential, as well as excitatory postsynaptic potential and spike frequencies. We explored, with whole-cell patch clamp, TRH effect on action potential shape in pyramidal neurons of the sensorimotor cortex. TRH reduced spike and after hyperpolarization amplitudes, and increased spike half-width. The effect varied with dose, time and cortical layer. In layer V, 0.5µM of TRH induced a small increase in spike half-width, while 1 and 5µM induced a strong but transient change in spike half-width, and amplitude; after hyperpolarization amplitude was modified at 5µM of TRH. Cortical layers III and VI neurons responded intensely to 0.5µM TRH; layer II neurons response was small. The effect of 1µM TRH on action potential shape in layer V neurons was blocked by G-protein inhibition. Inhibition of the activity of the TRH-degrading enzyme pyroglutamyl peptidase II (PPII) reproduced the effect of TRH, with enhanced spike half-width. Many cortical PPII mRNA+ cells were VGLUT1 mRNA+, and some GAD mRNA+. These data show that TRH regulates action potential shape in pyramidal cortical neurons, and are consistent with the hypothesis that PPII controls its action in this region.
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Affiliation(s)
- Víctor Rodríguez-Molina
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), AP 70250, México, D.F. 04510, México; Facultad de Medicina, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México
| | - Javier Patiño
- Facultad de Medicina, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México
| | - Yamili Vargas
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Ave. Universidad 2001, Chamilpa, Cuernavaca, Morelos 62210, México
| | - Edith Sánchez-Jaramillo
- Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría, Ramón de la Fuente Muñíz, México D.F., México
| | - Patricia Joseph-Bravo
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Ave. Universidad 2001, Chamilpa, Cuernavaca, Morelos 62210, México
| | - Jean-Louis Charli
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Ave. Universidad 2001, Chamilpa, Cuernavaca, Morelos 62210, México.
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Butt AM, Fern RF, Matute C. Neurotransmitter signaling in white matter. Glia 2014; 62:1762-79. [PMID: 24753049 DOI: 10.1002/glia.22674] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 03/04/2014] [Accepted: 03/31/2014] [Indexed: 12/16/2022]
Abstract
White matter (WM) tracts are bundles of myelinated axons that provide for rapid communication throughout the CNS and integration in grey matter (GM). The main cells in myelinated tracts are oligodendrocytes and astrocytes, with small populations of microglia and oligodendrocyte precursor cells. The prominence of neurotransmitter signaling in WM, which largely exclude neuronal cell bodies, indicates it must have physiological functions other than neuron-to-neuron communication. A surprising aspect is the diversity of neurotransmitter signaling in WM, with evidence for glutamatergic, purinergic (ATP and adenosine), GABAergic, glycinergic, adrenergic, cholinergic, dopaminergic and serotonergic signaling, acting via a wide range of ionotropic and metabotropic receptors. Both axons and glia are potential sources of neurotransmitters and may express the respective receptors. The physiological functions of neurotransmitter signaling in WM are subject to debate, but glutamate and ATP-mediated signaling have been shown to evoke Ca(2+) signals in glia and modulate axonal conduction. Experimental findings support a model of neurotransmitters being released from axons during action potential propagation acting on glial receptors to regulate the homeostatic functions of astrocytes and myelination by oligodendrocytes. Astrocytes also release neurotransmitters, which act on axonal receptors to strengthen action potential propagation, maintaining signaling along potentially long axon tracts. The co-existence of multiple neurotransmitters in WM tracts suggests they may have diverse functions that are important for information processing. Furthermore, the neurotransmitter signaling phenomena described in WM most likely apply to myelinated axons of the cerebral cortex and GM areas, where they are doubtless important for higher cognitive function.
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Affiliation(s)
- Arthur M Butt
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, United Kingdom
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Jung S, Bang M, Kim BS, Lee S, Kotov NA, Kim B, Jeon D. Intracellular gold nanoparticles increase neuronal excitability and aggravate seizure activity in the mouse brain. PLoS One 2014; 9:e91360. [PMID: 24625829 PMCID: PMC3953378 DOI: 10.1371/journal.pone.0091360] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 02/10/2014] [Indexed: 12/16/2022] Open
Abstract
Due to their inert property, gold nanoparticles (AuNPs) have drawn considerable attention; their biological application has recently expanded to include nanomedicine and neuroscience. However, the effect of AuNPs on the bioelectrical properties of a single neuron remains unknown. Here we present the effect of AuNPs on a single neuron under physiological and pathological conditions in vitro. AuNPs were intracellularly applied to hippocampal CA1 neurons from the mouse brain. The electrophysiological property of CA1 neurons treated with 5- or 40-nm AuNPs was assessed using the whole-cell patch-clamp technique. Intracellular application of AuNPs increased both the number of action potentials (APs) and input resistance. The threshold and duration of APs and the after hyperpolarization (AHP) were decreased by the intracellular AuNPs. In addition, intracellular AuNPs elicited paroxysmal depolarizing shift-like firing patterns during sustained repetitive firings (SRF) induced by prolonged depolarization (10 sec). Furthermore, low Mg2+-induced epileptiform activity was aggravated by the intracellular AuNPs. In this study, we demonstrated that intracellular AuNPs alter the intrinsic properties of neurons toward increasing their excitability, and may have deleterious effects on neurons under pathological conditions, such as seizure. These results provide some considerable direction on application of AuNPs into central nervous system (CNS).
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Affiliation(s)
- Seungmoon Jung
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Minji Bang
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Byung Sun Kim
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Sungmun Lee
- Department of Biomedical Engineering, Khalifa University of Science, Technology, and Research, Abu Dhabi, United Arab Emirates
| | - Nicholas A. Kotov
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Bongsoo Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Daejong Jeon
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
- * E-mail:
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Rattay F, Potrusil T, Wenger C, Wise AK, Glueckert R, Schrott-Fischer A. Impact of morphometry, myelinization and synaptic current strength on spike conduction in human and cat spiral ganglion neurons. PLoS One 2013; 8:e79256. [PMID: 24260179 PMCID: PMC3832640 DOI: 10.1371/journal.pone.0079256] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 09/20/2013] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Our knowledge about the neural code in the auditory nerve is based to a large extent on experiments on cats. Several anatomical differences between auditory neurons in human and cat are expected to lead to functional differences in speed and safety of spike conduction. METHODOLOGY/PRINCIPAL FINDINGS Confocal microscopy was used to systematically evaluate peripheral and central process diameters, commonness of myelination and morphology of spiral ganglion neurons (SGNs) along the cochlea of three human and three cats. Based on these morphometric data, model analysis reveales that spike conduction in SGNs is characterized by four phases: a postsynaptic delay, constant velocity in the peripheral process, a presomatic delay and constant velocity in the central process. The majority of SGNs are type I, connecting the inner hair cells with the brainstem. In contrast to those of humans, type I neurons of the cat are entirely myelinated. Biophysical model evaluation showed delayed and weak spikes in the human soma region as a consequence of a lack of myelin. The simulated spike conduction times are in accordance with normal interwave latencies from auditory brainstem response recordings from man and cat. Simulated 400 pA postsynaptic currents from inner hair cell ribbon synapses were 15 times above threshold. They enforced quick and synchronous spiking. Both of these properties were not present in type II cells as they receive fewer and much weaker (∼26 pA) synaptic stimuli. CONCLUSIONS/SIGNIFICANCE Wasting synaptic energy boosts spike initiation, which guarantees the rapid transmission of temporal fine structure of auditory signals. However, a lack of myelin in the soma regions of human type I neurons causes a large delay in spike conduction in comparison with cat neurons. The absent myelin, in combination with a longer peripheral process, causes quantitative differences of temporal parameters in the electrically stimulated human cochlea compared to the cat cochlea.
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Affiliation(s)
- Frank Rattay
- Institute for Analysis and Scientific Computing, Vienna University of Technology, Vienna, Austria
| | - Thomas Potrusil
- Department of Otorhinolaryngology, Innsbruck Medical University, Innsbruck, Austria
- Faculty of Informatics, Vienna University of Technology, Vienna, Austria
| | - Cornelia Wenger
- Institute of Biophysics and Biomedical Engeneering, Faculty of Science, University of Lisbon, Lisbon, Portugal
| | | | - Rudolf Glueckert
- Department of Otorhinolaryngology, Innsbruck Medical University, Innsbruck, Austria
- University Clinics Innsbruck, Tiroler Landeskrankenanstalten, Innsbruck, Austria
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Su CK, Chiang CH, Lee CM, Fan YP, Ho CM, Shyu LY. Computational solution of spike overlapping using data-based subtraction algorithms to resolve synchronous sympathetic nerve discharge. Front Comput Neurosci 2013; 7:149. [PMID: 24198782 PMCID: PMC3813947 DOI: 10.3389/fncom.2013.00149] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Accepted: 10/09/2013] [Indexed: 01/09/2023] Open
Abstract
Sympathetic nerves conveying central commands to regulate visceral functions often display activities in synchronous bursts. To understand how individual fibers fire synchronously, we establish "oligofiber recording techniques" to record "several" nerve fiber activities simultaneously, using in vitro splanchnic sympathetic nerve-thoracic spinal cord preparations of neonatal rats as experimental models. While distinct spike potentials were easily recorded from collagenase-dissociated sympathetic fibers, a problem arising from synchronous nerve discharges is a higher incidence of complex waveforms resulted from spike overlapping. Because commercial softwares do not provide an explicit solution for spike overlapping, a series of custom-made LabVIEW programs incorporated with MATLAB scripts was therefore written for spike sorting. Spikes were represented as data points after waveform feature extraction and automatically grouped by k-means clustering followed by principal component analysis (PCA) to verify their waveform homogeneity. For dissimilar waveforms with exceeding Hotelling's T(2) distances from the cluster centroids, a unique data-based subtraction algorithm (SA) was used to determine if they were the complex waveforms resulted from superimposing a spike pattern close to the cluster centroid with the other signals that could be observed in original recordings. In comparisons with commercial software, higher accuracy was achieved by analyses using our algorithms for the synthetic data that contained synchronous spiking and complex waveforms. Moreover, both T(2)-selected and SA-retrieved spikes were combined as unit activities. Quantitative analyses were performed to evaluate if unit activities truly originated from single fibers. We conclude that applications of our programs can help to resolve synchronous sympathetic nerve discharges (SND).
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Affiliation(s)
- Chun-Kuei Su
- Institute of Biomedical Sciences, Academia Sinica Taipei, Taiwan
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50
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Judy JT, Zandi PP. A review of potassium channels in bipolar disorder. Front Genet 2013; 4:105. [PMID: 23781230 PMCID: PMC3678088 DOI: 10.3389/fgene.2013.00105] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 05/22/2013] [Indexed: 12/11/2022] Open
Abstract
Although bipolar disorder (BP) is one of the most heritable psychiatric conditions, susceptibility genes for the disorder have yet to be conclusively identified. It is likely that variants in multiple genes across multiple pathways contribute to the genotype–phenotype relationship in the affected population. Recent evidence from genome-wide association studies implicates an entire class of genes related to the structure and regulation of ion channels, suggesting that the etiology of BP may arise from channelopathies. In this review, we examine the evidence for this hypothesis, with a focus on the potential role of voltage-gated potassium channels. We consider evidence from genetic and expression studies, and discuss the potential underlying biology. We consider animal models and treatment implications of the involvement of potassium ion channelopathy in BP. Finally, we explore intriguing parallels between BP and epilepsy, the signature channelopathy of the central nervous system.
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Affiliation(s)
- Jennifer T Judy
- Department of Psychiatry, Johns Hopkins School of Medicine Baltimore, MD, USA
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