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Li Y, Fang Y, Li K, Yang H, Duan S, Sun L. Morphological Tracing and Functional Identification of Monosynaptic Connections in the Brain: A Comprehensive Guide. Neurosci Bull 2024; 40:1364-1378. [PMID: 38700806 PMCID: PMC11365912 DOI: 10.1007/s12264-024-01196-0] [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: 11/15/2023] [Accepted: 01/19/2024] [Indexed: 09/01/2024] Open
Abstract
Behavioral studies play a crucial role in unraveling the mechanisms underlying brain function. Recent advances in optogenetics, neuronal typing and labeling, and circuit tracing have facilitated the dissection of the neural circuitry involved in various important behaviors. The identification of monosynaptic connections, both upstream and downstream of specific neurons, serves as the foundation for understanding complex neural circuits and studying behavioral mechanisms. However, the practical implementation and mechanistic understanding of monosynaptic connection tracing techniques and functional identification remain challenging, particularly for inexperienced researchers. Improper application of these methods and misinterpretation of results can impede experimental progress and lead to erroneous conclusions. In this paper, we present a comprehensive description of the principles, specific operational details, and key steps involved in tracing anterograde and retrograde monosynaptic connections. We outline the process of functionally identifying monosynaptic connections through the integration of optogenetics and electrophysiological techniques, providing practical guidance for researchers.
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Affiliation(s)
- Yuanyuan Li
- Affiliated Mental Health Center and Hangzhou Seventh People's Hospital and School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou, 310058, China
- Liangzhu Laboratory, MOE Frontier Science Center for Brain Science and Brain-machine Integration, State Key Laboratory of Brain-machine Intelligence, Zhejiang University, Hangzhou, 311121, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University, Hangzhou, 310058, China
| | - Yuanyuan Fang
- Affiliated Mental Health Center and Hangzhou Seventh People's Hospital and School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou, 310058, China
- Liangzhu Laboratory, MOE Frontier Science Center for Brain Science and Brain-machine Integration, State Key Laboratory of Brain-machine Intelligence, Zhejiang University, Hangzhou, 311121, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University, Hangzhou, 310058, China
- Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100005, China
| | - Kaiyuan Li
- Affiliated Mental Health Center and Hangzhou Seventh People's Hospital and School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou, 310058, China
- Liangzhu Laboratory, MOE Frontier Science Center for Brain Science and Brain-machine Integration, State Key Laboratory of Brain-machine Intelligence, Zhejiang University, Hangzhou, 311121, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University, Hangzhou, 310058, China
| | - Hongbin Yang
- Affiliated Mental Health Center and Hangzhou Seventh People's Hospital and School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou, 310058, China
- Liangzhu Laboratory, MOE Frontier Science Center for Brain Science and Brain-machine Integration, State Key Laboratory of Brain-machine Intelligence, Zhejiang University, Hangzhou, 311121, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University, Hangzhou, 310058, China
| | - Shumin Duan
- Liangzhu Laboratory, MOE Frontier Science Center for Brain Science and Brain-machine Integration, State Key Laboratory of Brain-machine Intelligence, Zhejiang University, Hangzhou, 311121, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University, Hangzhou, 310058, China
- Department of Neurobiology and Department of Neurology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Li Sun
- Affiliated Mental Health Center and Hangzhou Seventh People's Hospital and School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou, 310058, China.
- Liangzhu Laboratory, MOE Frontier Science Center for Brain Science and Brain-machine Integration, State Key Laboratory of Brain-machine Intelligence, Zhejiang University, Hangzhou, 311121, China.
- NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University, Hangzhou, 310058, China.
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Bryson M, Kloefkorn H, Idlett-Ali S, Carrasco DI, Noble DJ, Martin K, Sawchuk MA, Au Yong N, Garraway SM, Hochman S. Emergent epileptiform activity in spinal sensory circuits drives ectopic bursting in afferent axons and sensory dysfunction after cord injury. Pain 2024:00006396-990000000-00676. [PMID: 39106457 DOI: 10.1097/j.pain.0000000000003364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 06/25/2024] [Indexed: 08/09/2024]
Abstract
ABSTRACT Spinal cord injury leads to hyperexcitability and dysfunction in spinal sensory processing. As hyperexcitable circuits can become epileptiform, we explored whether such activity emerges in a thoracic spinal cord injury (SCI) contusion model of neuropathic pain. Recordings from spinal sensory axons in multiple below-lesion segmental dorsal roots demonstrated that SCI facilitated the emergence of spontaneous ectopic burst spiking in afferent axons, which were correlated across multiple adjacent dorsal roots. Burst frequency correlated with behavioral mechanosensitivity. The same bursting events were recruited by afferent stimulation, and timing interactions with ongoing spontaneous bursts revealed that recruitment was limited by a prolonged post-burst refractory period. Ectopic bursting in afferent axons was driven by GABAA receptor activation, presumably by conversion of subthreshold GABAergic interneuronal presynaptic axoaxonic inhibitory actions to suprathreshold spiking. Collectively, the emergence of stereotyped bursting circuitry with hypersynchrony, sensory input activation, post-burst refractory period, and reorganization of connectivity represent defining features of an epileptiform network. Indeed, these same features were reproduced in naive animals with the convulsant 4-aminopyridine (fampridine). We conclude that spinal cord injury promotes the emergence of epileptiform activity in spinal sensory networks that promote profound corruption of sensory signaling. This includes hyperexcitability and bursting by ectopic spiking in afferent axons that propagate bidirectionally by reentrant central and peripheral projections as well as sensory circuit hypoexcitability during the burst refractory period. More broadly, the work links circuit hyperexcitability to epileptiform circuit emergence, further strengthening it as a conceptual basis to understand features of sensory dysfunction and neuropathic pain.
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Affiliation(s)
- Matthew Bryson
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Heidi Kloefkorn
- Department of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, OR, United States
| | | | - Dario I Carrasco
- Department of Neurosurgery, Emory University School of Medicine, Atlanta, GA, United States
| | - Donald James Noble
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Karmarcha Martin
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Michael A Sawchuk
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Nicholas Au Yong
- Department of Neurosurgery, Emory University School of Medicine, Atlanta, GA, United States
| | - Sandra M Garraway
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Shawn Hochman
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
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3
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Hoven D, Inaoka M, McCoy R, Withers A, Owens RM, Malliaras GG. Simple dynamic cell culture system reduces recording noise in microelectrode array recordings. MRS COMMUNICATIONS 2024; 14:261-266. [PMID: 38966401 PMCID: PMC11219396 DOI: 10.1557/s43579-024-00554-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 04/11/2024] [Indexed: 07/06/2024]
Abstract
Microelectrode arrays (MEAs) have applications in drug discovery, toxicology, and basic research. They measure the electrophysiological response of tissue cultures to quantify changes upon exposure to biochemical stimuli. Unfortunately, manual addition of chemicals introduces significant noise in the recordings. Here, we report a simple-to-fabricate fluidic system that addresses this issue. We show that cell cultures can be successfully established in the fluidic compartment under continuous flow conditions and that the addition of chemicals introduces minimal noise in the recordings. This dynamic cell culture system represents an improvement over traditional tissue culture wells used in MEAs, facilitating electrophysiology measurements. Graphical abstract
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Affiliation(s)
- Darius Hoven
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA UK
| | - Misaki Inaoka
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA UK
| | - Reece McCoy
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS UK
| | - Aimee Withers
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS UK
| | - Róisín M. Owens
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS UK
| | - George G. Malliaras
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA UK
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Morris PG, Taylor JD, Paton JFR, Nogaret A. Single shot detection of alterations across multiple ionic currents from assimilation of cell membrane dynamics. Sci Rep 2024; 14:6031. [PMID: 38472404 DOI: 10.1038/s41598-024-56576-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 03/08/2024] [Indexed: 03/14/2024] Open
Abstract
The dysfunction of ion channels is a causative factor in a variety of neurological diseases, thereby defining the implicated channels as key drug targets. The detection of functional changes in multiple specific ionic currents currently presents a challenge, particularly when the neurological causes are either a priori unknown, or are unexpected. Traditional patch clamp electrophysiology is a powerful tool in this regard but is low throughput. Here, we introduce a single-shot method for detecting alterations amongst a range of ion channel types from subtle changes in membrane voltage in response to a short chaotically driven current clamp protocol. We used data assimilation to estimate the parameters of individual ion channels and from these we reconstructed ionic currents which exhibit significantly lower error than the parameter estimates. Such reconstructed currents thereby become sensitive predictors of functional alterations in biological ion channels. The technique correctly predicted which ionic current was altered, and by approximately how much, following pharmacological blockade of BK, SK, A-type K+ and HCN channels in hippocampal CA1 neurons. We anticipate this assay technique could aid in the detection of functional changes in specific ionic currents during drug screening, as well as in research targeting ion channel dysfunction.
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Affiliation(s)
- Paul G Morris
- Department of Physics, University of Bath, Claverton Down, Bath, UK
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Joseph D Taylor
- Department of Physics, University of Bath, Claverton Down, Bath, UK
| | - Julian F R Paton
- Manaaki Manawa - the Centre for Heart Research, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Grafton, Auckland, New Zealand
| | - Alain Nogaret
- Department of Physics, University of Bath, Claverton Down, Bath, UK.
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Varadi G. Mechanism of Analgesia by Gabapentinoid Drugs: Involvement of Modulation of Synaptogenesis and Trafficking of Glutamate-Gated Ion Channels. J Pharmacol Exp Ther 2024; 388:121-133. [PMID: 37918854 DOI: 10.1124/jpet.123.001669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 10/18/2023] [Accepted: 10/23/2023] [Indexed: 11/04/2023] Open
Abstract
Gabapentinoids have clinically been used for treating epilepsy, neuropathic pain, and several other neurologic disorders for >30 years; however, the definitive molecular mechanism responsible for their therapeutic actions remained uncertain. The conventional pharmacological observation regarding their efficacy in chronic pain modulation is the weakening of glutamate release at presynaptic terminals in the spinal cord. While the α2/δ-1 subunit of voltage-gated calcium channels (VGCCs) has been identified as the primary drug receptor for gabapentinoids, the lack of consistent effect of this drug class on VGCC function is indicative of a minor role in regulating this ion channel's activity. The current review targets the efficacy and mechanism of gabapentinoids in treating chronic pain. The discovery of interaction of α2/δ-1 with thrombospondins established this protein as a major synaptogenic neuronal receptor for thrombospondins. Other findings identified α2/δ-1 as a powerful regulator of N-methyl-D-aspartate receptor (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) by potentiating the synaptic expression, a putative pathophysiological mechanism of neuropathic pain. Further, the interdependent interactions between thrombospondin and α2/δ-1 contribute to chronic pain states, while gabapentinoid ligands efficaciously reverse such pain conditions. Gabapentin normalizes and even blocks NMDAR and AMPAR synaptic targeting and activity elicited by nerve injury. SIGNIFICANCE STATEMENT: Gabapentinoid drugs are used to treat various neurological conditions including chronic pain. In chronic pain states, gene expression of cacnα2/δ-1 and thrombospondins are upregulated and promote aberrant excitatory synaptogenesis. The complex trait of protein associations that involve interdependent interactions between α2/δ-1 and thrombospondins, further, association of N-methyl-D-aspartate receptor and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor with the C-tail of α2/δ-1, constitutes a macromolecular signaling complex that forms the crucial elements for the pharmacological mode of action of gabapentinoids.
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Chalil SMK, Chandrasekharan IP, Kathirvel S, Katta RR. Ultra-High Performance Liquid Chromatography Method for Bioanalysis of Fampridine Using Dried Blood Spot (DBS) Methodology: Application to Pharmacokinetic Study in Albino Rats. J Chromatogr Sci 2023:bmad062. [PMID: 37567585 DOI: 10.1093/chromsci/bmad062] [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: 04/26/2023] [Revised: 06/28/2023] [Accepted: 07/26/2023] [Indexed: 08/13/2023]
Abstract
Fampridine (dalfampridine) is used to improve walking in people who have multiple sclerosis (a disease in which the nerves do not function properly and may cause weakness, numbness, loss of muscle coordination and problems with vision, speech and bladder control). Measurement of fampridine plasma concentrations is not practical at sites lacking the facilities to prepare and process blood samples. A dried blood spot (DBS) sampling method, in which a few drops of blood, drawn by lancet from the finger, are applied onto specially manufactured absorbent filter paper, can be used as an alternative to plasma monitoring and would allow for simplified sample storage and transport. Using blood samples from pharmacokinetic studies, an ultra-high performance liquid chromatography assay method for quantification of fampridine in DBS is developed and validated for specificity, selectivity, accuracy, precision, reproducibility and stability. Method was specific and selective relative to endogenous compounds, with required process efficiency, and no matrix effect. Inaccuracy and precision for intra-day and inter-day analyses were tested at all concentrations. Quantification of fampridine in DBS assay was not affected by blood deposit volume and punch position within spot, and hematocrit level had a limited but acceptable effect on measurement accuracy. Fampridine was stable for at least 2 months at room temperature. The correlation between DBS and plasma concentrations with an average blood-to-plasma ratio is determined. DBS sampling is a simple and practical method for monitoring fampridine concentrations. The method is completely validated as per ICH guidelines and extended to the in vivo determination of fampridine in male albino rats.
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Affiliation(s)
- Sheba M K Chalil
- National College of Pharmacy, KMCT Group of Institutions, Manassery, Kozhikode 673602, Kerala, India
| | | | - Singaram Kathirvel
- National College of Pharmacy, KMCT Group of Institutions, Manassery, Kozhikode 673602, Kerala, India
| | - Raja R Katta
- Department of Pharmaceutical Analysis, Sri Sivani College of Pharmacy, Srikakulam 532 402, Andhra Pradesh, India
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Al-Hassany L, Boucherie DM, Creeney H, van Drie RWA, Farham F, Favaretto S, Gollion C, Grangeon L, Lyons H, Marschollek K, Onan D, Pensato U, Stanyer E, Waliszewska-Prosół M, Wiels W, Chen HZ, Amin FM. Future targets for migraine treatment beyond CGRP. J Headache Pain 2023; 24:76. [PMID: 37370051 DOI: 10.1186/s10194-023-01567-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Accepted: 03/14/2023] [Indexed: 06/29/2023] Open
Abstract
BACKGROUND Migraine is a disabling and chronic neurovascular headache disorder. Trigeminal vascular activation and release of calcitonin gene-related peptide (CGRP) play a pivotal role in the pathogenesis of migraine. This knowledge has led to the development of CGRP(-receptor) therapies. Yet, a substantial proportion of patients do not respond to these treatments. Therefore, alternative targets for future therapies are warranted. The current narrative review provides a comprehensive overview of the pathophysiological role of these possible non-CGRP targets in migraine. FINDINGS We covered targets of the metabotropic receptors (pituitary adenylate cyclase-activating polypeptide (PACAP), vasoactive intestinal peptide (VIP), amylin, and adrenomedullin), intracellular targets (nitric oxide (NO), phosphodiesterase-3 (PDE3) and -5 (PDE5)), and ion channels (potassium, calcium, transient receptor potential (TRP), and acid-sensing ion channels (ASIC)). The majority of non-CGRP targets were able to induce migraine-like attacks, except for (i) calcium channels, as it is not yet possible to directly target channels to elucidate their precise involvement in migraine; (ii) TRP channels, activation of which can induce non-migraine headache; and (iii) ASICs, as their potential in inducing migraine attacks has not been investigated thus far. Drugs that target its receptors exist for PACAP, NO, and the potassium, TRP, and ASIC channels. No selective drugs exist for the other targets, however, some existing (migraine) treatments appear to indirectly antagonize responses to amylin, adrenomedullin, and calcium channels. Drugs against PACAP, NO, potassium channels, TRP channels, and only a PAC1 antibody have been tested for migraine treatment, albeit with ambiguous results. CONCLUSION While current research on these non-CGRP drug targets has not yet led to the development of efficacious therapies, human provocation studies using these targets have provided valuable insight into underlying mechanisms of migraine headaches and auras. Further studies are needed on these alternative therapies in non-responders of CGRP(-receptor) targeted therapies with the ultimate aim to pave the way towards a headache-free future for all migraine patients.
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Affiliation(s)
- Linda Al-Hassany
- Department of Internal Medicine, Division of Vascular Medicine and Pharmacology, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Deirdre M Boucherie
- Department of Internal Medicine, Division of Vascular Medicine and Pharmacology, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Hannah Creeney
- Wolfson Centre for Age-Related Diseases, King's College London, London, UK
| | - Ruben W A van Drie
- Department of Internal Medicine, Division of Vascular Medicine and Pharmacology, Erasmus MC University Medical Center, Rotterdam, The Netherlands
- Department of Cardiology, Division of Experimental Cardiology, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Fatemeh Farham
- Department of Headache, Iranian Centre of Neurological Researchers, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Silvia Favaretto
- Headache Center, Neurology Clinic, University Hospital of Padua, Padua, Italy
| | - Cédric Gollion
- Department of Neurology, University Hospital of Toulouse, Toulouse, France
| | - Lou Grangeon
- Neurology Department, Rouen University Hospital, Rouen, France
| | - Hannah Lyons
- Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Karol Marschollek
- Department of Neurology, Wroclaw Medical University, Wrocław, Poland
| | - Dilara Onan
- Spine Health Unit, Faculty of Physical Therapy and Rehabilitation, Hacettepe University, Ankara, Turkey
- Department of Clinical and Molecular Medicine, Sapienza University, Rome, Italy
| | - Umberto Pensato
- Neurology and Stroke Unit, IRCCS Humanitas Research Hospital, Rozzano, Milan, Italy
- Humanitas University, Pieve Emanuele, Milan, Italy
| | - Emily Stanyer
- Wolfson Centre for Age-Related Diseases, King's College London, London, UK
| | | | - Wietse Wiels
- Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Brussels, Belgium
| | - Hui Zhou Chen
- Wolfson Centre for Age-Related Diseases, King's College London, London, UK
| | - Faisal Mohammad Amin
- Danish Headache Center, Department of Neurology, Faculty of Health and Medical Sciences, Rigshospitalet Glostrup, University of Copenhagen, Copenhagen, Denmark.
- Department of Neurorehabilitation/Traumatic Brain Injury, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
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4-Aminopyridine Induces Nerve Growth Factor to Improve Skin Wound Healing and Tissue Regeneration. Biomedicines 2022; 10:biomedicines10071649. [PMID: 35884953 PMCID: PMC9313269 DOI: 10.3390/biomedicines10071649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 06/29/2022] [Accepted: 07/02/2022] [Indexed: 11/30/2022] Open
Abstract
The discovery of ways to enhance skin wound healing is of great importance due to the frequency of skin lesions. We discovered that 4-aminopyridine (4-AP), a potassium channel blocker approved by the FDA for improving walking ability in multiple sclerosis, greatly enhances skin wound healing. Benefits included faster wound closure, restoration of normal-appearing skin architecture, and reinnervation. Hair follicle neogenesis within the healed wounds was increased, both histologically and by analysis of K15 and K17 expression. 4-AP increased levels of vimentin (fibroblasts) and alpha-smooth muscle actin (α-SMA, collagen-producing myofibroblasts) in the healed dermis. 4-AP also increased neuronal regeneration with increased numbers of axons and S100+ Schwann cells (SCs), and increased expression of SRY-Box Transcription Factor 10 (SOX10). Treatment also increased levels of transforming growth factor-β (TGF-β), substance P, and nerve growth factor (NGF), important promoters of wound healing. In vitro studies demonstrated that 4-AP induced nerve growth factor and enhanced proliferation and migration of human keratinocytes. Thus, 4-AP enhanced many of the key attributes of successful wound healing and offers a promising new approach to enhance skin wound healing and tissue regeneration.
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Jiménez-Altayó F, Cabrera A, Bagán A, Giménez-Llort L, D’Ocon P, Pérez B, Pallàs M, Escolano C. An Imidazoline 2 Receptor Ligand Relaxes Mouse Aorta via Off-Target Mechanisms Resistant to Aging. Front Pharmacol 2022; 13:826837. [PMID: 35645795 PMCID: PMC9133327 DOI: 10.3389/fphar.2022.826837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 04/26/2022] [Indexed: 11/13/2022] Open
Abstract
Imidazoline receptors (IR) are classified into three receptor subtypes (I1R, I2R, and I3R) and previous studies showed that regulation of I2R signaling has neuroprotective potential. In order to know if I2R has a role in modulating vascular tone in health and disease, we evaluated the putative vasoactive effects of two recently synthesized I2R ligands, diethyl (1RS,3aSR,6aSR)-5-(3-chloro-4-fluorophenyl)-4,6-dioxo-1-phenyl-1,3a,4,5,6,6a-hexahydropyrrolo[3,4-c]pyrrole -1-phosphonate (B06) and diethyl [(1-(3-chloro-4-fluorobenzyl)-5,5-dimethyl-4-phenyl-4,5-dihydro-1H-imidazol-4-yl]phosphonate] (MCR5). Thoracic aortas from Oncins France 1 (3- to 4-months-old) and C57BL/6 (3- to 4- and 16- to 17-months-old mice) were mounted in tissue baths to measure isometric tension. In young mice of both strains, MCR5 induced greater relaxations than either B06 or the high-affinity I2R selective ligand 2-(2-benzofuranyl)-2-imidazoline (2-BFI), which evoked marginal responses. MCR5 relaxations were independent of I2R, as IR ligands did not significantly affect them, involved activation of smooth muscle KATP channels and inhibition of L-type voltage-gated Ca2+ channels, and were only slightly modulated by endothelium-derived nitric oxide (negatively) and prostacyclin (positively). Notably, despite the presence of endothelial dysfunction in old mice, MCR5 relaxations were preserved. In conclusion, the present study provides evidence against a functional contribution of I2R in the modulation of vascular tone in the mouse aorta. Moreover, the I2R ligand MCR5 is an endothelium-independent vasodilator that acts largely via I2R-independent pathways and is resistant to aging. We propose MCR5 as a candidate drug for the management of vascular disease in the elderly.
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Affiliation(s)
- Francesc Jiménez-Altayó
- Department of Pharmacology, Therapeutics and Toxicology, School of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain
- Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
- *Correspondence: Francesc Jiménez-Altayó,
| | - Anna Cabrera
- Department of Pharmacology, Therapeutics and Toxicology, School of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain
- Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Andrea Bagán
- Laboratory of Medicinal Chemistry (Associated Unit to CSIC), Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, Institute of Biomedicine (IBUB), University of Barcelona, Barcelona, Spain
| | - Lydia Giménez-Llort
- Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
- Department of Psychiatry and Forensic Medicine, School of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Pilar D’Ocon
- Department of Pharmacology, School of Medicine, Universidad de Valencia, Burjassot, Spain
- Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universidad de Valencia, Valencia, Spain
| | - Belén Pérez
- Department of Pharmacology, Therapeutics and Toxicology, School of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain
- Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Mercè Pallàs
- Pharmacology Section, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, Institut de Neurociències, University of Barcelona, Barcelona, Spain
| | - Carmen Escolano
- Laboratory of Medicinal Chemistry (Associated Unit to CSIC), Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, Institute of Biomedicine (IBUB), University of Barcelona, Barcelona, Spain
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10
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Radomski KL, Zi X, Lischka FW, Noble MD, Galdzicki Z, Armstrong RC. Acute axon damage and demyelination are mitigated by 4-aminopyridine (4-AP) therapy after experimental traumatic brain injury. Acta Neuropathol Commun 2022; 10:67. [PMID: 35501931 PMCID: PMC9059462 DOI: 10.1186/s40478-022-01366-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 04/11/2022] [Indexed: 11/10/2022] Open
Abstract
Damage to long axons in white matter tracts is a major pathology in closed head traumatic brain injury (TBI). Acute TBI treatments are needed that protect against axon damage and promote recovery of axon function to prevent long term symptoms and neurodegeneration. Our prior characterization of axon damage and demyelination after TBI led us to examine repurposing of 4-aminopyridine (4-AP), an FDA-approved inhibitor of voltage-gated potassium (Kv) channels. 4-AP is currently indicated to provide symptomatic relief for patients with chronic stage multiple sclerosis, which involves axon damage and demyelination. We tested clinically relevant dosage of 4-AP as an acute treatment for experimental TBI and found multiple benefits in corpus callosum axons. This randomized, controlled pre-clinical study focused on the first week after TBI, when axons are particularly vulnerable. 4-AP treatment initiated one day post-injury dramatically reduced axon damage detected by intra-axonal fluorescence accumulations in Thy1-YFP mice of both sexes. Detailed electron microscopy in C57BL/6 mice showed that 4-AP reduced pathological features of mitochondrial swelling, cytoskeletal disruption, and demyelination at 7 days post-injury. Furthermore, 4-AP improved the molecular organization of axon nodal regions by restoring disrupted paranode domains and reducing Kv1.2 channel dispersion. 4-AP treatment did not resolve deficits in action potential conduction across the corpus callosum, based on ex vivo electrophysiological recordings at 7 days post-TBI. Thus, this first study of 4-AP effects on axon damage in the acute period demonstrates a significant decrease in multiple pathological hallmarks of axon damage after experimental TBI.
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Affiliation(s)
- Kryslaine L. Radomski
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
- Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
| | - Xiaomei Zi
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
- Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
| | - Fritz W. Lischka
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
- Biomedical Instrumentation Center, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
| | - Mark D. Noble
- Department of Biomedical Genetics, School of Medicine and Dentistry, University of Rochester, 601 Elmwood Ave, Box 633, Rochester, NY 14642 USA
| | - Zygmunt Galdzicki
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
- Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
| | - Regina C. Armstrong
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
- Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814 USA
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11
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Hyperactivation is sufficient to release porcine sperm from immobilized oviduct glycans. Sci Rep 2022; 12:6446. [PMID: 35440797 PMCID: PMC9019019 DOI: 10.1038/s41598-022-10390-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 03/14/2022] [Indexed: 11/09/2022] Open
Abstract
Fertilizing sperm are retained by adhesion to specific glycans on the epithelium of the oviduct forming a reservoir before sperm are released from the reservoir so fertilization can ensue. Capacitated sperm lose affinity for the oviduct epithelium but the components of capacitation that are important for sperm release are uncertain. One important correlate of capacitation is the development of hyperactivated motility. Hyperactivation is characterized by asymmetrical flagellar beating with high beat amplitude. We tested whether the development of full-type asymmetrical motility was sufficient to release sperm from immobilized oviduct glycans. Sperm hyperactivation was induced by four different compounds, a cell-permeable cAMP analog (cBiMPS), CatSper activators (4-aminopyridine and procaine), and an endogenous steroid (progesterone). Using standard analysis (CASA) and direct visualization with high-speed video microscopy, we first confirmed that all four compounds induced hyperactivation. Subsequently, sperm were allowed to bind to immobilized oviduct glycans, and compounds or vehicle controls were added. All compounds caused sperm release from immobilized glycans, demonstrating that hyperactivation was sufficient to release sperm from oviduct cells and immobilized glycans. Pharmacological inhibition of the non-genomic progesterone receptor and CatSper diminished sperm release from oviduct glycans. Inhibition of the proteolytic activities of the ubiquitin-proteasome system (UPS), implicated in the regulation of sperm capacitation, diminished sperm release in response to all hyperactivation inducers. In summary, induction of sperm hyperactivation was sufficient to induce sperm release from immobilized oviduct glycans and release was dependent on CatSper and the UPS.
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12
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Clifford AM, Tresguerres M, Goss GG, Wood CM. A novel K + -dependent Na + uptake mechanism during low pH exposure in adult zebrafish (Danio rerio): New tricks for old dogma. Acta Physiol (Oxf) 2022; 234:e13777. [PMID: 34985194 DOI: 10.1111/apha.13777] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 09/27/2021] [Accepted: 01/01/2022] [Indexed: 12/16/2022]
Abstract
AIM To determine whether Na+ uptake in adult zebrafish (Danio rerio) exposed to acidic water adheres to traditional models reliant on Na+ /H+ Exchangers (NHEs), Na+ channels and Na+ /Cl- Cotransporters (NCCs) or if it occurs through a novel mechanism. METHODS Zebrafish were exposed to control (pH 8.0) or acidic (pH 4.0) water for 0-12 hours during which 22 Na+ uptake ( J Na in ), ammonia excretion, net acidic equivalent flux and net K+ flux ( J H net ) were measured. The involvement of NHEs, Na+ channels, NCCs, K+ -channels and K+ -dependent Na+ /Ca2+ exchangers (NCKXs) was evaluated by exposure to Cl- -free or elevated [K+ ] water, or to pharmacological inhibitors. The presence of NCKXs in gill was examined using RT-PCR. RESULTS J Na in was strongly attenuated by acid exposure, but gradually recovered to control rates. The systematic elimination of each of the traditional models led us to consider K+ as a counter substrate for Na+ uptake during acid exposure. Indeed, elevated environmental [K+ ] inhibited J Na in during acid exposure in a concentration-dependent manner, with near-complete inhibition at 10 mM. Moreover, J H net loss increased approximately fourfold at 8-10 hours of acid exposure which correlated with recovered J Na in in 1:1 fashion, and both J Na in and J H net were sensitive to tetraethylammonium (TEA) during acid exposure. Zebrafish gills expressed mRNA coding for six NCKX isoforms. CONCLUSIONS During acid exposure, zebrafish engage a novel Na+ uptake mechanism that utilizes the outwardly directed K+ gradient as a counter-substrate for Na+ and is sensitive to TEA. NKCXs are promising candidates to mediate this K+ -dependent Na+ uptake, opening new research avenues about Na+ uptake in zebrafish and other acid-tolerant aquatic species.
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Affiliation(s)
- Alexander M. Clifford
- Department of Zoology University of British Columbia Vancouver British Columbia Canada
- Marine Biology Research Division Scripps Institution of Oceanography University of California San Diego La Jolla California USA
| | - Martin Tresguerres
- Marine Biology Research Division Scripps Institution of Oceanography University of California San Diego La Jolla California USA
| | - Greg G. Goss
- Department of Biological Sciences University of Alberta Edmonton Alberta Canada
| | - Chris M. Wood
- Department of Zoology University of British Columbia Vancouver British Columbia Canada
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13
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Ahtiainen A, Genocchi B, Tanskanen JMA, Barros MT, Hyttinen JAK, Lenk K. Astrocytes Exhibit a Protective Role in Neuronal Firing Patterns under Chemically Induced Seizures in Neuron-Astrocyte Co-Cultures. Int J Mol Sci 2021; 22:12770. [PMID: 34884577 PMCID: PMC8657549 DOI: 10.3390/ijms222312770] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/19/2021] [Accepted: 11/22/2021] [Indexed: 12/12/2022] Open
Abstract
Astrocytes and neurons respond to each other by releasing transmitters, such as γ-aminobutyric acid (GABA) and glutamate, that modulate the synaptic transmission and electrochemical behavior of both cell types. Astrocytes also maintain neuronal homeostasis by clearing neurotransmitters from the extracellular space. These astrocytic actions are altered in diseases involving malfunction of neurons, e.g., in epilepsy, Alzheimer's disease, and Parkinson's disease. Convulsant drugs such as 4-aminopyridine (4-AP) and gabazine are commonly used to study epilepsy in vitro. In this study, we aim to assess the modulatory roles of astrocytes during epileptic-like conditions and in compensating drug-elicited hyperactivity. We plated rat cortical neurons and astrocytes with different ratios on microelectrode arrays, induced seizures with 4-AP and gabazine, and recorded the evoked neuronal activity. Our results indicated that astrocytes effectively counteracted the effect of 4-AP during stimulation. Gabazine, instead, induced neuronal hyperactivity and synchronicity in all cultures. Furthermore, our results showed that the response time to the drugs increased with an increasing number of astrocytes in the co-cultures. To the best of our knowledge, our study is the first that shows the critical modulatory role of astrocytes in 4-AP and gabazine-induced discharges and highlights the importance of considering different proportions of cells in the cultures.
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Affiliation(s)
- Annika Ahtiainen
- Faculty of Medicine and Health Technology, Tampere University, 33520 Tampere, Finland; (J.M.A.T.); (M.T.B.); (J.A.K.H.); (K.L.)
| | - Barbara Genocchi
- Faculty of Medicine and Health Technology, Tampere University, 33520 Tampere, Finland; (J.M.A.T.); (M.T.B.); (J.A.K.H.); (K.L.)
| | - Jarno M. A. Tanskanen
- Faculty of Medicine and Health Technology, Tampere University, 33520 Tampere, Finland; (J.M.A.T.); (M.T.B.); (J.A.K.H.); (K.L.)
| | - Michael T. Barros
- Faculty of Medicine and Health Technology, Tampere University, 33520 Tampere, Finland; (J.M.A.T.); (M.T.B.); (J.A.K.H.); (K.L.)
- School of Computer Science and Electronic Engineering, University of Essex, Colchester CO4 3SQ, UK
| | - Jari A. K. Hyttinen
- Faculty of Medicine and Health Technology, Tampere University, 33520 Tampere, Finland; (J.M.A.T.); (M.T.B.); (J.A.K.H.); (K.L.)
| | - Kerstin Lenk
- Faculty of Medicine and Health Technology, Tampere University, 33520 Tampere, Finland; (J.M.A.T.); (M.T.B.); (J.A.K.H.); (K.L.)
- Institute of Neural Engineering, Graz University of Technology, 8010 Graz, Austria
- BioTechMed, 8010 Graz, Austria
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14
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Paguigan ND, Yan Y, Karthikeyan M, Chase K, Carter J, Leavitt LS, Lim AL, Lin Z, Memon T, Christensen S, Bentzen BH, Schmitt N, Reilly CA, Teichert RW, Raghuraman S, Olivera BM, Schmidt EW. The Tunicate Metabolite 2-(3,5-Diiodo-4-methoxyphenyl)ethan-1-amine Targets Ion Channels of Vertebrate Sensory Neurons. ACS Chem Biol 2021; 16:1654-1662. [PMID: 34423964 DOI: 10.1021/acschembio.1c00328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Marine tunicates produce defensive amino-acid-derived metabolites, including 2-(3,5-diiodo-4-methoxyphenyl)ethan-1-amine (DIMTA), but their mechanisms of action are rarely known. Using an assay-guided approach, we found that out of the many different sensory cells in the mouse dorsal root ganglion (DRG), DIMTA selectively affected low-threshold cold thermosensors. Whole-cell electrophysiology experiments using DRG cells, channels expressed in Xenopus oocytes, and human cell lines revealed that DIMTA blocks several potassium channels, reducing the magnitude of the afterhyperpolarization and increasing the baseline intracellular calcium concentration [Ca2+]i of low-threshold cold thermosensors. When injected into mice, DIMTA increased the threshold of cold sensation by >3 °C. DIMTA may thus serve as a lead in the further design of compounds that inhibit problems in the cold-sensory system, such as cold allodynia and other neuropathic pain conditions.
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Affiliation(s)
- Noemi D. Paguigan
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah 81112, United States
| | - Yannan Yan
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark
| | - Manju Karthikeyan
- Department of Biology, University of Utah, Salt Lake City, Utah 81112, United States
| | - Kevin Chase
- Department of Biology, University of Utah, Salt Lake City, Utah 81112, United States
| | - Jackson Carter
- Department of Biology, University of Utah, Salt Lake City, Utah 81112, United States
| | - Lee S. Leavitt
- Department of Biology, University of Utah, Salt Lake City, Utah 81112, United States
| | - Albebson L. Lim
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah 81112, United States
| | - Zhenjian Lin
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah 81112, United States
| | - Tosifa Memon
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah 81112, United States
| | - Sean Christensen
- Department of Biology, University of Utah, Salt Lake City, Utah 81112, United States
| | - Bo H. Bentzen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark
| | - Nicole Schmitt
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark
| | - Christopher A. Reilly
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah 81112, United States
| | - Russell W. Teichert
- Department of Biology, University of Utah, Salt Lake City, Utah 81112, United States
| | | | - Baldomero M. Olivera
- Department of Biology, University of Utah, Salt Lake City, Utah 81112, United States
| | - Eric W. Schmidt
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah 81112, United States
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15
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Presynaptic Paraneoplastic Disorders of the Neuromuscular Junction: An Update. Brain Sci 2021; 11:brainsci11081035. [PMID: 34439654 PMCID: PMC8392118 DOI: 10.3390/brainsci11081035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 07/26/2021] [Accepted: 08/02/2021] [Indexed: 01/17/2023] Open
Abstract
The neuromuscular junction (NMJ) is the target of a variety of immune-mediated disorders, usually classified as presynaptic and postsynaptic, according to the site of the antigenic target and consequently of the neuromuscular transmission alteration. Although less common than the classical autoimmune postsynaptic myasthenia gravis, presynaptic disorders are important to recognize due to the frequent association with cancer. Lambert Eaton myasthenic syndrome is due to a presynaptic failure to release acetylcholine, caused by antibodies to the presynaptic voltage-gated calcium channels. Acquired neuromyotonia is a condition characterized by nerve hyperexcitability often due to the presence of antibodies against proteins associated with voltage-gated potassium channels. This review will focus on the recent developments in the autoimmune presynaptic disorders of the NMJ.
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16
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Page SJ, Kasner SE, Bockbrader M, Goldstein M, Finklestein SP, Ning M, El-Feky WH, Wilson CA, Roberts H. A double-blind, randomized, controlled study of two dose strengths of dalfampridine extended release on walking deficits in ischemic stroke. Restor Neurol Neurosci 2021; 38:301-309. [PMID: 32651338 PMCID: PMC7592666 DOI: 10.3233/rnn-201009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Stroke-induced ischemia affects both cortex and underlying white matter. Dalfampridine extended release tablets (D-ER) enhance action potential conduction in demyelinated axons, which may positively affect post-stroke recovery. OBJECTIVE Based on promising preliminary data, we compared efficacy of D-ER administered at 7.5 mg or 10 mg with placebo on post-stroke ambulation. Primary study outcome (response) was a ≥20% increase on the 2-minute walk test (2 MinWT) at 12 weeks after first drug administration. METHODS This was a multicenter, randomized, placebo-controlled, 3-arm, parallel-group, safety and efficacy trial. After obtaining baseline measures of 2 MinWT, Walk-12, and Timed Up and Go, subjects entered a 2-week, single-blind placebo run-in period and were randomized 1:1:1 to receive 7.5 mg D-ER, 10 mg D-ER, or placebo, dosed twice-daily for 12 weeks. Follow-up evaluations occurred at weeks 14 and 16 when subjects were off study drug. RESULTS The study was terminated early with 377 of planned 540 patients enrolled, due to no treatment effect. At week 12, mean increase in distances walked in 2 minutes were similar among the 3 study groups (14.9±40.0 feet; 19.4±39.6 feet; and 20.4±38.3 feet for placebo, 7.5 mg D-ER, and 10 mg D-ER, respectively). The proportion of subjects who showed ≥20% improvement on 2 MinWT at week 12 was 13.5%, 14.0%, and 19.0%, for placebo, 7.5 mg D-ER, and 10 mg D-ER, respectively; these were nonsignificant changes from baseline for all groups. CONCLUSIONS D-ER at either a 7.5-mg or 10-mg dose did not significantly increase performance on the 2 MinWT in stroke survivors with gait impairment, although this study was terminated early before full enrollment. (Clinical Trial # NCT02271217).
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Affiliation(s)
| | | | | | | | | | - MingMing Ning
- Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | | | | | - Holly Roberts
- Acorda Therapeutics, Inc., Ardsley, NY, USA,Correspondence to: Holly Roberts, MD, Acorda Therapeutics, Inc., 420 Saw Mill River Road, Ardsley, NY 10502, USA.
Tel.: (914) 326 5224; E-mail:
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17
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Abstract
K+ channels enable potassium to flow across the membrane with great selectivity. There are four K+ channel families: voltage-gated K (Kv), calcium-activated (KCa), inwardly rectifying K (Kir), and two-pore domain potassium (K2P) channels. All four K+ channels are formed by subunits assembling into a classic tetrameric (4x1P = 4P for the Kv, KCa, and Kir channels) or tetramer-like (2x2P = 4P for the K2P channels) architecture. These subunits can either be the same (homomers) or different (heteromers), conferring great diversity to these channels. They share a highly conserved selectivity filter within the pore but show different gating mechanisms adapted for their function. K+ channels play essential roles in controlling neuronal excitability by shaping action potentials, influencing the resting membrane potential, and responding to diverse physicochemical stimuli, such as a voltage change (Kv), intracellular calcium oscillations (KCa), cellular mediators (Kir), or temperature (K2P).
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18
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Bertagna F, Lewis R, Silva SRP, McFadden J, Jeevaratnam K. Effects of electromagnetic fields on neuronal ion channels: a systematic review. Ann N Y Acad Sci 2021; 1499:82-103. [PMID: 33945157 DOI: 10.1111/nyas.14597] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 02/09/2021] [Accepted: 03/12/2021] [Indexed: 12/18/2022]
Abstract
Many aspects of chemistry and biology are mediated by electromagnetic field (EMF) interactions. The central nervous system (CNS) is particularly sensitive to EMF stimuli. Studies have explored the direct effect of different EMFs on the electrical properties of neurons in the last two decades, particularly focusing on the role of voltage-gated ion channels (VGCs). This work aims to systematically review published evidence in the last two decades detailing the effects of EMFs on neuronal ion channels as per the PRISM guidelines. Following a predetermined exclusion and inclusion criteria, 22 papers were included after searches on three online databases. Changes in calcium homeostasis, attributable to the voltage-gated calcium channels, were found to be the most commonly reported result of EMF exposure. EMF effects on the neuronal landscape appear to be diverse and greatly dependent on parameters, such as the field's frequency, exposure time, and intrinsic properties of the irradiated tissue, such as the expression of VGCs. Here, we systematically clarify how neuronal ion channels are particularly affected and differentially modulated by EMFs at multiple levels, such as gating dynamics, ion conductance, concentration in the membrane, and gene and protein expression. Ion channels represent a major transducer for EMF-related effects on the CNS.
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Affiliation(s)
- Federico Bertagna
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, Surrey, UK.,School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK
| | - Rebecca Lewis
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, Surrey, UK.,School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK
| | - S Ravi P Silva
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, Surrey, UK.,Advanced Technology Institute, University of Surrey, Guildford, Surrey, UK
| | - Johnjoe McFadden
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, Surrey, UK.,School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK
| | - Kamalan Jeevaratnam
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford, Surrey, UK.,School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK
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19
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Cromwell EF, Leung M, Hammer M, Thai A, Rajendra R, Sirenko O. Disease Modeling with 3D Cell-Based Assays Using a Novel Flowchip System and High-Content Imaging. SLAS Technol 2021; 26:237-248. [PMID: 33783259 DOI: 10.1177/24726303211000688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
There is an increasing interest in using three-dimensional (3D) cell structures for modeling tumors, organs, and tissue to accelerate translational research. We describe here a novel automated organoid assay system (the Pu·MA System) combined with microfluidic-based flowchips that can facilitate 3D cell-based assays. The flowchip is composed of sample wells, which contain organoids, connected to additional multiple wells that can hold various assay reagents. Organoids are positioned in a protected chamber in sample wells, and fluids are exchanged from side reservoirs using pressure-driven flow. Media exchange, sample staining, wash steps, and other processes can be performed without disruption to or loss of 3D sample. The bottom of the sample chamber is thin, optically clear plastic compatible with high-content imaging (HCI). The whole system can be kept in an incubator, allowing long-term cellular assays to be performed. We present two examples of use of the system for biological research. In the first example, cytotoxicity effects of anticancer drugs were evaluated on HeLa and HepG2 spheroids using HCI and vascular endothelial growth factor expression. In the second application, the flowchip system was used for the functional evaluation of Ca2+ oscillations in neurospheroids. Neurospheres were incubated with neuroactive compounds, and neuronal activity was assessed using Ca2+-sensitive dyes and fast kinetic fluorescence imaging. This novel assay system using microfluidics enables automation of 3D cell-based cultures that mimic in vivo conditions, performs multidosing protocols and multiple media exchanges, provides gentle handling of spheroids and organoids, and allows a wide range of assay detection modalities.
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20
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Ryzhkina I, Murtazina L, Gainutdinov K, Konovalov A. Diluted Aqueous Dispersed Systems of 4-Aminopyridine: The Relationship of Self-Organization, Physicochemical Properties, and Influence on the Electrical Characteristics of Neurons. Front Chem 2021; 9:623860. [PMID: 33796504 PMCID: PMC8007878 DOI: 10.3389/fchem.2021.623860] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 02/01/2021] [Indexed: 11/22/2022] Open
Abstract
A variety of physicochemical methods were used to examine the self-organization, physicochemical, UV absorption, and fluorescent properties of diluted aqueous solutions (calculated concentrations from 1·10-20 to 1·10-2 M) of the membrane voltage-dependent potassium channels blocker 4-aminopyridine (4-AP). Using the dynamic light scattering method, it was shown that 4-AP solutions at concentrations in the range of 1·10-20-1·10-6 M are dispersed systems in which domains and nanoassociates of hundreds of nm in size are formed upon dilution. An interrelation between the non-monotonic concentration dependencies of the size of the dispersed phase, the fluorescence intensity (λ ex 225 nm, λ em 340 nm), specific electrical conductivity, and pH has been established. This allows us to predict the bioeffects of the 4-AP systems at low concentrations. The impact of these diluted aqueous systems on the electrical characteristics of identified neurons of Helix lucorum snails was studied. Incubation of neurons in the 4-AP systems for which the formation of domains and nanoassociates had been established lead to a nonmonotonic decrease of the resting potential by 7-13%. An analysis of the obtained results and published data allows for a conclusion that a consistent change in the nature and parameters of the dispersed phase, as well as the pH of the medium, apparently determines the nonmonotonic nature of the effect of the 4-AP systems in a 1·10-20-1·10-6 M concentration range on the resting membrane potential of neurons. It was found that the pre-incubation of neurons in the 4-AP system with a concentration of 1·10-12 M led to a 17.0% synergistic decrease in the membrane potential after a subsequent treatment with 1·10-2 M 4-AP solution. This finding demonstrates a significant modifying effect of self-organized dispersed systems of 4-AP in low concentrations on the neurons' sensitivity to 4-AP.
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Affiliation(s)
- Irina Ryzhkina
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, Kazan, Russia
| | - Lyaisan Murtazina
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, Kazan, Russia
| | - Khalil Gainutdinov
- Zavoisky Physical-Technical Institute, FRC Kazan Scientific Center, Russian Academy of Sciences, Kazan, Russia
| | - Alexander Konovalov
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, Kazan, Russia
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21
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Ojala KS, Ginebaugh SP, Wu M, Miller EW, Ortiz G, Covarrubias M, Meriney SD. A high-affinity, partial antagonist effect of 3,4-diaminopyridine mediates action potential broadening and enhancement of transmitter release at NMJs. J Biol Chem 2021; 296:100302. [PMID: 33465376 PMCID: PMC7949096 DOI: 10.1016/j.jbc.2021.100302] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 01/12/2021] [Accepted: 01/14/2021] [Indexed: 12/03/2022] Open
Abstract
3,4-Diaminopyridine (3,4-DAP) increases transmitter release from neuromuscular junctions (NMJs), and low doses of 3,4-DAP (estimated to reach ∼1 μM in serum) are the Food and Drug Administration (FDA)-approved treatment for neuromuscular weakness caused by Lambert–Eaton myasthenic syndrome. Canonically, 3,4-DAP is thought to block voltage-gated potassium (Kv) channels, resulting in prolongation of the presynaptic action potential (AP). However, recent reports have shown that low millimolar concentrations of 3,4-DAP have an off-target agonist effect on the Cav1 subtype (“L-type”) of voltage-gated calcium (Cav) channels and have speculated that this agonist effect might contribute to 3,4-DAP effects on transmitter release at the NMJ. To address 3,4-DAP’s mechanism(s) of action, we first used the patch-clamp electrophysiology to characterize the concentration-dependent block of 3,4-DAP on the predominant presynaptic Kv channel subtypes found at the mammalian NMJ (Kv3.3 and Kv3.4). We identified a previously unreported high-affinity (1–10 μM) partial antagonist effect of 3,4-DAP in addition to the well-known low-affinity (0.1–1 mM) antagonist activity. We also showed that 1.5-μM DAP had no effects on Cav1.2 or Cav2.1 current. Next, we used voltage imaging to show that 1.5- or 100-μM 3,4-DAP broadened the AP waveform in a dose-dependent manner, independent of Cav1 calcium channels. Finally, we demonstrated that 1.5- or 100-μM 3,4-DAP augmented transmitter release in a dose-dependent manner and this effect was also independent of Cav1 channels. From these results, we conclude that low micromolar concentrations of 3,4-DAP act solely on Kv channels to mediate AP broadening and enhance transmitter release at the NMJ.
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Affiliation(s)
- Kristine S Ojala
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Scott P Ginebaugh
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Man Wu
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Evan W Miller
- Departments of Chemistry and Molecular & Cell Biology, University of California, Berkeley, Berkeley, California, USA
| | - Gloria Ortiz
- Departments of Chemistry and Molecular & Cell Biology, University of California, Berkeley, Berkeley, California, USA
| | - Manuel Covarrubias
- Department of Neuroscience, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Stephen D Meriney
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
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22
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Assembly and Function of the Juxtaparanodal Kv1 Complex in Health and Disease. Life (Basel) 2020; 11:life11010008. [PMID: 33374190 PMCID: PMC7824554 DOI: 10.3390/life11010008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 12/21/2020] [Accepted: 12/23/2020] [Indexed: 02/07/2023] Open
Abstract
The precise axonal distribution of specific potassium channels is known to secure the shape and frequency of action potentials in myelinated fibers. The low-threshold voltage-gated Kv1 channels located at the axon initial segment have a significant influence on spike initiation and waveform. Their role remains partially understood at the juxtaparanodes where they are trapped under the compact myelin bordering the nodes of Ranvier in physiological conditions. However, the exposure of Kv1 channels in de- or dys-myelinating neuropathy results in alteration of saltatory conduction. Moreover, cell adhesion molecules associated with the Kv1 complex, including Caspr2, Contactin2, and LGI1, are target antigens in autoimmune diseases associated with hyperexcitability such as encephalitis, neuromyotonia, or neuropathic pain. The clustering of Kv1.1/Kv1.2 channels at the axon initial segment and juxtaparanodes is based on interactions with cell adhesion molecules and cytoskeletal linkers. This review will focus on the trafficking and assembly of the axonal Kv1 complex in the peripheral and central nervous system (PNS and CNS), during development, and in health and disease.
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Bursting in cerebellar stellate cells induced by pharmacological agents: Non-sequential spike adding. PLoS Comput Biol 2020; 16:e1008463. [PMID: 33315892 PMCID: PMC7769625 DOI: 10.1371/journal.pcbi.1008463] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 12/28/2020] [Accepted: 10/22/2020] [Indexed: 12/26/2022] Open
Abstract
Cerebellar stellate cells (CSCs) are spontaneously active, tonically firing (5-30 Hz), inhibitory interneurons that synapse onto Purkinje cells. We previously analyzed the excitability properties of CSCs, focusing on four key features: type I excitability, non-monotonic first-spike latency, switching in responsiveness and runup (i.e., temporal increase in excitability during whole-cell configuration). In this study, we extend this analysis by using whole-cell configuration to show that these neurons can also burst when treated with certain pharmacological agents separately or jointly. Indeed, treatment with 4-Aminopyridine (4-AP), a partial blocker of delayed rectifier and A-type K+ channels, at low doses induces a bursting profile in CSCs significantly different than that produced at high doses or when it is applied at low doses but with cadmium (Cd2+), a blocker of high voltage-activated (HVA) Ca2+ channels. By expanding a previously revised Hodgkin–Huxley type model, through the inclusion of Ca2+-activated K+ (K(Ca)) and HVA currents, we explain how these bursts are generated and what their underlying dynamics are. Specifically, we demonstrate that the expanded model preserves the four excitability features of CSCs, as well as captures their bursting patterns induced by 4-AP and Cd2+. Model investigation reveals that 4-AP is potentiating HVA, inducing square-wave bursting at low doses and pseudo-plateau bursting at high doses, whereas Cd2+ is potentiating K(Ca), inducing pseudo-plateau bursting when applied in combination with low doses of 4-AP. Using bifurcation analysis, we show that spike adding in square-wave bursts is non-sequential when gradually changing HVA and K(Ca) maximum conductances, delayed Hopf is responsible for generating the plateau segment within the active phase of pseudo-plateau bursts, and bursting can become “chaotic” when HVA and K(Ca) maximum conductances are made low and high, respectively. These results highlight the secondary effects of the drugs applied and suggest that CSCs have all the ingredients needed for bursting. Excitable cells, including neurons, fire action potentials (APs) in their membrane voltage that allow them to communicate with each other and to serve certain physiological purposes. They do so either tonically by firing APs periodically, or episodically by repeatedly firing clusters of APs (called bursts) separated by quiescent periods. Each one of those firing patterns can be neuron-specific and dependent on synaptic inputs and/or their physiological environment. Cerebellar stellate cells (CSCs) that synapse onto Purkinje cells, the sole output of the cerebellum responsible for motor control, are spontaneously active inhibitory interneurons that fire APs tonically. We previously studied the excitability properties of these neurons and showed that they possess several important key features, including type I excitability, runup, non-monotonic first spike latency and switching in responsiveness. In this study, we show that CSCs can also exhibit two modes of burst firing, called square-wave and pseudo-plateau, when treated with certain pharmacological agents. Using bifurcation theory, we demonstrate that spike adding in the square-wave burst is non-sequential, changing by several spikes when certain conductances are altered gradually. This study thus sheds lights onto the overall effects of the pharmacological agents and highlights the ability of CSCs to burst in certain biological conditions.
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Chen Z, Boxwell A, Conte C, Haas T, Harley A, Terman DH, Travers SP, Travers JB. Kv4 channel expression and kinetics in GABAergic and non-GABAergic rNST neurons. J Neurophysiol 2020; 124:1727-1742. [PMID: 32997557 DOI: 10.1152/jn.00396.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The rostral nucleus of the solitary tract (rNST) serves as the first central relay in the gustatory system. In addition to synaptic interactions, central processing is also influenced by the ion channel composition of individual neurons. For example, voltage-gated K+ channels such as outward K+ current (IA) can modify the integrative properties of neurons. IA currents are prevalent in rNST projection cells but are also found to a lesser extent in GABAergic interneurons. However, characterization of the kinetic properties of IA, the molecular basis of these currents, as well as the consequences of IA on spiking properties of identified rNST cells is lacking. Here, we show that IA in rNST GABAergic (G+) and non-GABAergic (G-) neurons share a common molecular basis. In both cell types, there was a reduction in IA following treatment with the specific Kv4 channel blocker AmmTx3. However, the kinetics of activation and inactivation of IA in the two cell types were different with G- neurons having significantly more negative half-maximal activation and inactivation values. Likewise, under current clamp, G- cells had significantly longer delays to spike initiation in response to a depolarizing stimulus preceded by a hyperpolarizing prepulse. Computational modeling and dynamic clamp suggest that differences in the activation half-maximum may account for the differences in delay. We further observed evidence for a window current under both voltage clamp and current clamp protocols. We speculate that the location of Kv4.3 channels on dendrites, together with a window current for IA at rest, serves to regulate excitatory afferent inputs.NEW & NOTEWORTHY Here, we demonstrate that the transient outward K+ current IA occurs in both GABAergic and non-GABAergic neurons via Kv4.3 channels in the rostral (gustatory) solitary nucleus. Although found in both cell types, IA is more prevalent in non-GABAergic cells; a larger conductance at more negative potentials leads to a greater impact on spike initiation compared with GABAergic neurons. An IA window current further suggests that IA can regulate excitatory afferent input to the nucleus.
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Affiliation(s)
- Z Chen
- Division of Biosciences, Ohio State University, Columbus, Ohio
| | - A Boxwell
- College of Medicine, Ohio State University, Columbus, Ohio
| | - C Conte
- Department of Statistics, Ohio State University, Columbus, Ohio
| | - T Haas
- Division of Biosciences, Ohio State University, Columbus, Ohio
| | - A Harley
- Division of Biosciences, Ohio State University, Columbus, Ohio
| | - D H Terman
- Department of Mathematics, Ohio State University, Columbus, Ohio
| | - S P Travers
- Division of Biosciences, Ohio State University, Columbus, Ohio
| | - J B Travers
- Division of Biosciences, Ohio State University, Columbus, Ohio
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De Giglio L, Cortese F, Pennisi EM. Aminopiridines in the treatment of multiple sclerosis and other neurological disorders. Neurodegener Dis Manag 2020; 10:409-423. [PMID: 33054615 DOI: 10.2217/nmt-2020-0018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Symptomatic treatment has a great relevance for the management of patients with neurologic diseases, since it reduces disease burden and improves quality of life. Aminopyridines (APs) are a group of potassium (K+) channel blocking agents that exert their activity both at central nervous system level and on neuromuscular junction. This review describes the use of APs for the symptomatic treatment of neurological conditions. We will describe trials leading to the approval of the extended-release 4-aminopyridine for MS and evidence in support of the use in other neurological diseases.
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Affiliation(s)
- Laura De Giglio
- Department of Medicine, San Filippo Neri Hospital, Neurology Unit, Rome, Italy
| | - Francesca Cortese
- Department of Medicine, San Filippo Neri Hospital, Neurology Unit, Rome, Italy
| | - Elena Maria Pennisi
- Department of Medicine, San Filippo Neri Hospital, Neurology Unit, Rome, Italy
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26
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K channel blockage with 3,4-diaminopyridine potentiates the effect of L-DOPA on dopamine release in striatal slices prepared from 6-OHDA pre-treated rats. Exp Brain Res 2020; 238:2539-2548. [PMID: 32870323 DOI: 10.1007/s00221-020-05912-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 08/24/2020] [Indexed: 12/24/2022]
Abstract
Although L-DOPA revolutionized in the treatment of Parkinson's disease, most patients developed motor complications after several years of treatment. Adjunctive therapy to L-DOPA with drugs related to dopaminergic signaling may reduce its dose without decreasing the therapeutic efficiency and thus ameliorates its adverse effects. It has been shown that 3,4-diaminopyridine (3,4-DAP), a K channel blocker, increased dopamine release from striatal slices by increasing neuronal firing in striatal dopaminergic terminals. The current study investigates whether 3,4-DAP may enhance L-DOPA-induced dopamine (DA) release from striatal slices by increasing neuronal firing in striatal dopaminergic terminals. The effects of L-DOPA and 3,4-DAP on spontaneous DA and DOPAC release were tested in vitro, on acute rat striatal slices prepared from non-treated and 6-hydroxydopamine-pre-treated rats. DA and DOPAC levels were determined by HPLC methods. When 3,4-diaminopyridine was combined with L-DOPA, the observed effect was considerably greater than the increases induced by L-DOPA or 3,4-DAP alone in normoxic and neurodegenerative conditions produced by FeSO4 and 6-hydroxydopamine. Furthermore, L-DOPA plus 3,4-DAP also ameliorated DOPAC levels in neurodegenerative conditions. These data indicate that 3,4 DAP plus L-DOPA activates striatal dopaminergic terminals by increasing the DA release and, thus, could be considered as a promising finding in treatment of acute and chronic injury in dopaminergic neurons.
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27
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Dietrich M, Koska V, Hecker C, Göttle P, Hilla AM, Heskamp A, Lepka K, Issberner A, Hallenberger A, Baksmeier C, Steckel J, Balk L, Knier B, Korn T, Havla J, Martínez-Lapiscina EH, Solà-Valls N, Manogaran P, Olbert ED, Schippling S, Cruz-Herranz A, Yiu H, Button J, Caldito NG, von Gall C, Mausberg AK, Stettner M, Zimmermann HG, Paul F, Brandt AU, Küry P, Goebels N, Aktas O, Berndt C, Saidha S, Green AJ, Calabresi PA, Fischer D, Hartung HP, Albrecht P. Protective effects of 4-aminopyridine in experimental optic neuritis and multiple sclerosis. Brain 2020; 143:1127-1142. [PMID: 32293668 DOI: 10.1093/brain/awaa062] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 12/08/2019] [Accepted: 01/20/2020] [Indexed: 12/30/2022] Open
Abstract
Chronic disability in multiple sclerosis is linked to neuroaxonal degeneration. 4-aminopyridine (4-AP) is used and licensed as a symptomatic treatment to ameliorate ambulatory disability in multiple sclerosis. The presumed mode of action is via blockade of axonal voltage gated potassium channels, thereby enhancing conduction in demyelinated axons. In this study, we provide evidence that in addition to those symptomatic effects, 4-AP can prevent neuroaxonal loss in the CNS. Using in vivo optical coherence tomography imaging, visual function testing and histologic assessment, we observed a reduction in retinal neurodegeneration with 4-AP in models of experimental optic neuritis and optic nerve crush. These effects were not related to an anti-inflammatory mode of action or a direct impact on retinal ganglion cells. Rather, histology and in vitro experiments indicated 4-AP stabilization of myelin and oligodendrocyte precursor cells associated with increased nuclear translocation of the nuclear factor of activated T cells. In experimental optic neuritis, 4-AP potentiated the effects of immunomodulatory treatment with fingolimod. As extended release 4-AP is already licensed for symptomatic multiple sclerosis treatment, we performed a retrospective, multicentre optical coherence tomography study to longitudinally compare retinal neurodegeneration between 52 patients on continuous 4-AP therapy and 51 matched controls. In line with the experimental data, during concurrent 4-AP therapy, degeneration of the macular retinal nerve fibre layer was reduced over 2 years. These results indicate disease-modifying effects of 4-AP beyond symptomatic therapy and provide support for the design of a prospective clinical study using visual function and retinal structure as outcome parameters.
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Affiliation(s)
- Michael Dietrich
- Department of Neurology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Valeria Koska
- Department of Neurology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Christina Hecker
- Department of Neurology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Peter Göttle
- Department of Neurology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Alexander M Hilla
- Department of Cell Physiology, Faculty of Biology and Biotechnology, Ruhr-University Bochum, Bochum, Germany
| | - Annemarie Heskamp
- Department of Cell Physiology, Faculty of Biology and Biotechnology, Ruhr-University Bochum, Bochum, Germany
| | - Klaudia Lepka
- Department of Neurology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Andrea Issberner
- Department of Neurology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Angelika Hallenberger
- Institute of Anatomy II, Medical Faculty, Heinrich Heine University Düsseldorf, Germany
| | - Christine Baksmeier
- Department of Neurology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Julia Steckel
- Department of Neurology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Lisanne Balk
- Department of Neurology, Amsterdam Neuroscience, MS Center Amsterdam, VU University Medical Center, Amsterdam, The Netherlands
| | - Benjamin Knier
- Department of Experimental Neuroimmunology, Technische Universität München, Munich, Germany
| | - Thomas Korn
- Department of Experimental Neuroimmunology, Technische Universität München, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Joachim Havla
- Institute of Clinical Neuroimmunology, Ludwig-Maximilians University, Munich, Germany.,Data Integration for Future Medicine consortium (DIFUTURE), Ludwig-Maximilians University, Munich, Germany
| | - Elena H Martínez-Lapiscina
- Service of Neurology, Hospital Clinic, University of Barcelona, Spain Neuroimmunology Program, Institut d'Investigació Biomèdica August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Nuria Solà-Valls
- Service of Neurology, Hospital Clinic, University of Barcelona, Spain Neuroimmunology Program, Institut d'Investigació Biomèdica August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Praveena Manogaran
- Neuroimmunology and Multiple Sclerosis Research, Department of Neurology, University Hospital Zürich and University of Zürich, Zurich, Switzerland.,Department of Information Technology and Electrical Engineering, Swiss Federal Institute of Technology, Zurich, Switzerland
| | - Elisabeth D Olbert
- Neuroimmunology and Multiple Sclerosis Research, Department of Neurology, University Hospital Zürich and University of Zürich, Zurich, Switzerland
| | - Sven Schippling
- Neuroimmunology and Multiple Sclerosis Research, Department of Neurology, University Hospital Zürich and University of Zürich, Zurich, Switzerland.,Neuroscience Center Zurich, University of Zurich and Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
| | - Andrés Cruz-Herranz
- Division of Neuroinflammation and Glial Biology, Department of Neurology, University of California San Francisco, San Francisco, USA
| | - Hao Yiu
- Division of Neuroinflammation and Glial Biology, Department of Neurology, University of California San Francisco, San Francisco, USA
| | - Julia Button
- Division of Neuroimmunology and Neurological Infections, Johns Hopkins Hospital, Baltimore, USA
| | | | - Charlotte von Gall
- Institute of Anatomy II, Medical Faculty, Heinrich Heine University Düsseldorf, Germany
| | - Anne K Mausberg
- Department of Neurology, University Hospital Essen, Essen, Germany
| | - Mark Stettner
- Department of Neurology, University Hospital Essen, Essen, Germany
| | - Hannah G Zimmermann
- NeuroCure Clinical Research Center and Experimental and Clinical Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health and Max Delbrueck Center for Molecular Medicine, Berlin, Germany
| | - Friedemann Paul
- NeuroCure Clinical Research Center and Experimental and Clinical Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health and Max Delbrueck Center for Molecular Medicine, Berlin, Germany
| | - Alexander U Brandt
- NeuroCure Clinical Research Center and Experimental and Clinical Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health and Max Delbrueck Center for Molecular Medicine, Berlin, Germany.,Department of Neurology, University of California, Irvine, USA
| | - Patrick Küry
- Department of Neurology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Norbert Goebels
- Department of Neurology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Orhan Aktas
- Department of Neurology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Carsten Berndt
- Department of Neurology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Shiv Saidha
- Division of Neuroimmunology and Neurological Infections, Johns Hopkins Hospital, Baltimore, USA
| | - Ari J Green
- Division of Neuroinflammation and Glial Biology, Department of Neurology, University of California San Francisco, San Francisco, USA.,Department of Ophthalmology, University of California San Francisco, San Francisco, USA
| | - Peter A Calabresi
- Division of Neuroimmunology and Neurological Infections, Johns Hopkins Hospital, Baltimore, USA
| | - Dietmar Fischer
- Department of Cell Physiology, Faculty of Biology and Biotechnology, Ruhr-University Bochum, Bochum, Germany
| | - Hans-Peter Hartung
- Department of Neurology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Philipp Albrecht
- Department of Neurology, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
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Abstract
A limited number of peripheral targets generate pain. Inflammatory mediators can sensitize these. The review addresses targets acting exclusively or predominantly on sensory neurons, mediators involved in inflammation targeting sensory neurons, and mediators involved in a more general inflammatory process, of which an analgesic effect secondary to an anti-inflammatory effect can be expected. Different approaches to address these systems are discussed, including scavenging proinflammatory mediators, applying anti-inflammatory mediators, and inhibiting proinflammatory or facilitating anti-inflammatory receptors. New approaches are contrasted to established ones; the current stage of progress is mentioned, in particular considering whether there is data from a molecular and cellular level, from animals, or from human trials, including an early stage after a market release. An overview of publication activity is presented, considering a IuPhar/BPS-curated list of targets with restriction to pain-related publications, which was also used to identify topics.
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Affiliation(s)
- Cosmin I Ciotu
- Center of Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, 1090, Vienna, Austria
| | - Michael J M Fischer
- Center of Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, 1090, Vienna, Austria.
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Wu ZZ, Chen SR, Pan HL. Reply to Meriney and Lacomis: Comment on direct aminopyridine effects on voltage-gated Ca 2+ channels. J Biol Chem 2020; 293:16101. [PMID: 30315088 DOI: 10.1074/jbc.rl118.005655] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Zi-Zhen Wu
- From the Department of Neuroscience, Johns Hopkins University, Baltimore, Maryland 21205 and
| | - Shao-Rui Chen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Hui-Lin Pan
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
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30
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Meriney SD, Lacomis D. Reported direct aminopyridine effects on voltage-gated calcium channels is a high-dose pharmacological off-target effect of no clinical relevance. J Biol Chem 2020; 293:16100. [PMID: 30315087 DOI: 10.1074/jbc.l118.005425] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
| | - David Lacomis
- the Division of Neuromuscular Diseases, Department of Neurology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
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31
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Tejero R, Balk S, Franco-Espin J, Ojeda J, Hennlein L, Drexl H, Dombert B, Clausen JD, Torres-Benito L, Saal-Bauernschubert L, Blum R, Briese M, Appenzeller S, Tabares L, Jablonka S. R-Roscovitine Improves Motoneuron Function in Mouse Models for Spinal Muscular Atrophy. iScience 2020; 23:100826. [PMID: 31981925 PMCID: PMC6992996 DOI: 10.1016/j.isci.2020.100826] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 08/08/2019] [Accepted: 01/06/2020] [Indexed: 12/27/2022] Open
Abstract
Neurotransmission defects and motoneuron degeneration are hallmarks of spinal muscular atrophy, a monogenetic disease caused by the deficiency of the SMN protein. In the present study, we show that systemic application of R-Roscovitine, a Cav2.1/Cav2.2 channel modifier and a cyclin-dependent kinase 5 (Cdk-5) inhibitor, significantly improved survival of SMA mice. In addition, R-Roscovitine increased Cav2.1 channel density and sizes of the motor endplates. In vitro, R-Roscovitine restored axon lengths and growth cone sizes of Smn-deficient motoneurons corresponding to enhanced spontaneous Ca2+ influx and elevated Cav2.2 channel cluster formations independent of its capability to inhibit Cdk-5. Acute application of R-Roscovitine at the neuromuscular junction significantly increased evoked neurotransmitter release, increased the frequency of spontaneous miniature potentials, and lowered the activation threshold of silent terminals. These data indicate that R-Roscovitine improves Ca2+ signaling and Ca2+ homeostasis in Smn-deficient motoneurons, which is generally crucial for motoneuron differentiation, maturation, and function. R-Roscovitine prolongs survival of SMA mice R-Roscovitine increases Ca2+ influx and growth cone size of SMA motoneurons R-Roscovitine beneficially affects neurotransmission in SMA motor nerve terminals R-Roscovitine wakes up dormant synapses of SMA motoneurons
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Affiliation(s)
- Rocio Tejero
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
| | - Stefanie Balk
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Julio Franco-Espin
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
| | - Jorge Ojeda
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
| | - Luisa Hennlein
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Hans Drexl
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Benjamin Dombert
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Jan-Dierk Clausen
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Laura Torres-Benito
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain
| | | | - Robert Blum
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Michael Briese
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany
| | - Silke Appenzeller
- Comprehensive Cancer Center Mainfranken, University Hospital Würzburg, 97080 Würzburg, Germany; Core Unit SysMed, University of Würzburg, 97080 Würzburg, Germany
| | - Lucia Tabares
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, 41009 Seville, Spain.
| | - Sibylle Jablonka
- Institute of Clinical Neurobiology, University Hospital Würzburg, 97078 Würzburg, Germany.
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Study on Dalfampridine in the treatment of Multiple Sclerosis Mobility Disability: A meta-analysis. PLoS One 2019; 14:e0222288. [PMID: 31513613 PMCID: PMC6742383 DOI: 10.1371/journal.pone.0222288] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 08/26/2019] [Indexed: 11/19/2022] Open
Abstract
Objective Systematic Review was used to evaluate the efficacy and safety of Dalfampridine (DAP) in the treatment of Mobility Disability (MS) in patients with Multiple Sclerosis. Methods Clinical randomized controlled studies about DAP and placebo in the treatment of Mobility Disability in patients with Multiple Sclerosis until March 2019 were explored by searching Embase, PubMed, Cochrane, Web of Knowledge, and ClinicalTrials.gov. Literature screening, data extraction, quality assessment, and statistical analysis were performed by using Stata 14.0. Results 10 papers were included in the meta-analysis, and the number of patients was 2100. In conclusion, the application of DAP in clinical can significantly improve the Mobility Disability of patients [OR = 2.73, 95%CI (1.66, 4.50), P<0.001, I2 = 74.1%] and boost the mobility speed of patients in Timing 24 Minute Walk Test (T24FW) [SMD = 3,08, 95%CI(1,58, 4.58), P<0.001, I2 = 98.7%]. There are no significant differences of the incidence of adverse events [RR = 1.06, 95%CI (0.99, 1.14), P = 0.928, I2 = 0.0%] and urinary tract infection [RR = 1.21, 95%CI(0.91, 1.60), P = 0.145, I2 = 37.2%] between the DAP test group (Doses≤10 mg) and the placebo control group, and the incidence of adverse events [RR = 1.14, 95%CI(1.02, 1.28), P = 0.793, I2 = 0.0%] and urinary tract infection[RR = 3.05, 95%CI(1.04, 8.99), P = 0.680, I2 = 0.0%] for the DAP test group (Doses>10 mg) is a litter higher than the placebo control group. Conclusion DAP can effectively improve Mobility Disability in patients with Multiple Sclerosis, which is safe and reliable in specific DAP usage doses.
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Haghdoost-Yazdi H, Piri H, Najafipour R, Faraji A, Fraidouni N, Dargahi T, Alipour Heidari M. Blockade of fast A-type and TEA-sensitive potassium channels provide an antiparkinsonian effect in a 6-OHDA animal model. ACTA ACUST UNITED AC 2019; 22:44-50. [PMID: 28064330 PMCID: PMC5726837 DOI: 10.17712/nsj.2017.1.20160266] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Objective: To evaluate the effect of K+ channels inhibitors in treatment of parkinson’s disease (PD). Methods: This prospective comparative study was conducted in the Qazvin University of Medical Sciences, Iran, from April 2015 to January 2016. Male rats (n=37) received intraperitoneal doses of TEA (2 and 5 mg/kg) or 4-AP (0.5 and 1 mg/kg) twice-daily, before a stereotactic injection of 6-hydroxydopamine (6-OHDA) for the following 7 days. The 6-OHDA was injected into right medial forebrain bundle (MFB) of the rat brains. Development and severity of PD were assessed using the apomorphine-induced rotational test, the elevated body swing test and rotarod tests. Concentration of malondialdehyde (MDA), a marker of oxidative stress, was measured in rat sera. Results: Tetraethylammonium and 4-AP significantly reduced the number of apomorphine-induced rotations and improved motor learning in the rotarod test at both doses. Administration of 4-AP and TEA together was more effective than single administration of either agent. Malondialdehyde measurement showed that pretreatment with TEA could not prevent 6-OHDA-induced oxidative stress. Conclusion: Our results showed that pretreatment with TEA and 4-AP has a neuroprotective effect against 6-OHDA in dopaminergic neurons in the substantia nigra.
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Affiliation(s)
- Hashem Haghdoost-Yazdi
- Cellular and Molecular Research Center, Qazvin University of Medical Sciences, Qazvin, Iran
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Chen J, Li L, Chen SR, Chen H, Xie JD, Sirrieh RE, MacLean DM, Zhang Y, Zhou MH, Jayaraman V, Pan HL. The α2δ-1-NMDA Receptor Complex Is Critically Involved in Neuropathic Pain Development and Gabapentin Therapeutic Actions. Cell Rep 2019; 22:2307-2321. [PMID: 29490268 PMCID: PMC5873963 DOI: 10.1016/j.celrep.2018.02.021] [Citation(s) in RCA: 173] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 12/20/2017] [Accepted: 02/06/2018] [Indexed: 12/13/2022] Open
Abstract
α2δ-1, commonly known as a voltage-activated Ca2+ channel subunit, is a binding site of gabapentinoids used to treat neuropathic pain and epilepsy. However, it is unclear how α2δ-1 contributes to neuropathic pain and gabapentinoid actions. Here, we show that Cacna2d1 overexpression potentiates presynaptic and postsynaptic NMDAR activity of spinal dorsal horn neurons to cause pain hypersensitivity. Conversely, Cacna2d1 knockdown or ablation normalizes synaptic NMDAR activity increased by nerve injury. α2δ-1 forms a heteromeric complex with NMDARs in rodent and human spinal cords. The α2δ-1-NMDAR interaction predominantly occurs through the C terminus of α2δ-1 and promotes surface trafficking and synaptic targeting of NMDARs. Gabapentin or an α2δ-1 C terminus-interfering peptide normalizes NMDAR synaptic targeting and activity increased by nerve injury. Thus, α2δ-1 is an NMDAR-interacting protein that increases NMDAR synaptic delivery in neuropathic pain. Gabapentinoids reduce neuropathic pain by inhibiting forward trafficking of α2δ-1-NMDAR complexes.
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Affiliation(s)
- Jinjun Chen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, Hunan 410128, China
| | - Lingyong Li
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Shao-Rui Chen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Hong Chen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Jing-Dun Xie
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; Department of Anesthesiology, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong 510060, China
| | - Rita E Sirrieh
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center, Houston, TX 77030, USA
| | - David M MacLean
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center, Houston, TX 77030, USA
| | - Yuhao Zhang
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Meng-Hua Zhou
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Vasanthi Jayaraman
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center, Houston, TX 77030, USA
| | - Hui-Lin Pan
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
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Abstract
The large-conductance calcium- and voltage-activated K+ (BK) channel has a requirement of high intracellular free Ca2+ concentrations for its activation in neurons under physiological conditions. The Ca2+ sources for BK channel activation are not well understood. In this study, we showed by coimmunopurification and colocalization analyses that BK channels form complexes with NMDA receptors (NMDARs) in both rodent brains and a heterologous expression system. The BK-NMDAR complexes are broadly present in different brain regions. The complex formation occurs between the obligatory BKα and GluN1 subunits likely via a direct physical interaction of the former's intracellular S0-S1 loop with the latter's cytosolic regions. By patch-clamp recording on mouse brain slices, we observed BK channel activation by NMDAR-mediated Ca2+ influx in dentate gyrus granule cells. BK channels modulate excitatory synaptic transmission via functional coupling with NMDARs at postsynaptic sites of medial perforant path-dentate gyrus granule cell synapses. A synthesized peptide of the BKα S0-S1 loop region, when loaded intracellularly via recording pipette, abolished the NMDAR-mediated BK channel activation and effect on synaptic transmission. These findings reveal the broad expression of the BK-NMDAR complexes in brain, the potential mechanism underlying the complex formation, and the NMDAR-mediated activation and function of postsynaptic BK channels in neurons.
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Ma H, Chen S, Chen H, Zhou J, Li D, Pan H. α2δ-1 couples to NMDA receptors in the hypothalamus to sustain sympathetic vasomotor activity in hypertension. J Physiol 2018; 596:4269-4283. [PMID: 29971791 PMCID: PMC6117594 DOI: 10.1113/jp276394] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 06/29/2018] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS α2δ-1 is upregulated, promoting the interaction with NMDA receptors (NMDARs), in the hypothalamus in a rat model of hypertension. The prevalence of α2δ-1-bound NMDARs at synaptic sites in the hypothalamus is increased in hypertensive animals. α2δ-1 is essential for the increased presynaptic and postsynaptic NMDAR activity of hypothalamic neurons in hypertension. α2δ-1-bound NMDARs in the hypothalamus are critically involved in augmented sympathetic outflow in hypertensive animals. ABSTRACT Increased glutamate NMDA receptor (NMDAR) activity in the paraventricular nucleus (PVN) of the hypothalamus leads to augmented sympathetic outflow in hypertension. However, the molecular mechanisms underlying this effect remain unclear. α2δ-1, previously considered to be a voltage-activated calcium channel subunit, is a newly discovered powerful regulator of NMDARs. In the present study, we determined the role of α2δ-1 in regulating synaptic NMDAR activity of rostral ventrolateral medulla (RVLM)-projecting PVN neurons in spontaneously hypertensive rats (SHRs). We show that the protein levels of α2δ-1 and NMDARs in synaptosomes and the α2δ-1-NMDAR complexes in the hypothalamus were substantially higher in SHRs than in normotensive control rats. The basal amplitude of evoked NMDAR currents and NMDAR-mediated synaptic glutamate release in RVLM-projecting PVN neurons were significantly increased in SHRs. Strikingly, inhibiting α2δ-1 activity with gabapentin or disrupting the α2δ-1-NMDAR association with an α2δ-1 C-terminus peptide completely normalized the amplitude of evoked NMDAR currents and NMDAR-mediated synaptic glutamate release in RVLM-projecting PVN neurons in SHRs. In addition, microinjection of the α2δ-1 C-terminus peptide into the PVN substantially reduced arterial blood pressure and renal sympathetic nerve discharges in SHRs. Our findings indicate that α2δ-1-bound NMDARs in the PVN are required for the potentiated presynaptic and postsynaptic NMDAR activity of PVN presympathetic neurons and for the elevated sympathetic outflow in hypertension. α2δ-1-bound NMDARs may be an opportune target for treating neurogenic hypertension.
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Affiliation(s)
- Huijie Ma
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative MedicineThe University of Texas MD Anderson Cancer CenterHoustonTXUSA
- Department of PhysiologyHebei Medical UniversityShijiazhuangHebeiChina
| | - Shao‐Rui Chen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative MedicineThe University of Texas MD Anderson Cancer CenterHoustonTXUSA
| | - Hong Chen
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative MedicineThe University of Texas MD Anderson Cancer CenterHoustonTXUSA
| | - Jing‐Jing Zhou
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative MedicineThe University of Texas MD Anderson Cancer CenterHoustonTXUSA
| | - De‐Pei Li
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative MedicineThe University of Texas MD Anderson Cancer CenterHoustonTXUSA
| | - Hui‐Lin Pan
- Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative MedicineThe University of Texas MD Anderson Cancer CenterHoustonTXUSA
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Leussink VI, Montalban X, Hartung HP. Restoring Axonal Function with 4-Aminopyridine: Clinical Efficacy in Multiple Sclerosis and Beyond. CNS Drugs 2018; 32:637-651. [PMID: 29992409 DOI: 10.1007/s40263-018-0536-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The oral potassium channel blocker 4-aminopyridine has been used in various neurological conditions for decades. Numerous case reports and studies have supported its clinical efficacy in ameliorating the clinical presentation of certain neurological disorders. However, its short half-life, erratic drug levels, and safety-related dose restrictions limited its use as a self-compounded drug in clinical practice. This changed with the introduction of a prolonged-release formulation, which was successfully tested in patients with multiple sclerosis. It was fully approved by the US FDA in January 2010 but initially received only conditional approval from the European Medicines Agency (EMA) in July 2011. After additional clinical studies, this conditional approval was changed to unrestricted approval in August 2017. This article reviews and discusses these recent studies and places aminopyridines and their clinical utility into the context of a broader spectrum of neurological disorders, where clinical efficacy has been suggested. In 2010, prolonged-release 4-aminopyridine became the first drug specifically licensed to improve walking in patients with multiple sclerosis. About one-third of patients across disease courses benefit from this treatment. In addition, various reports indicate clinical efficacy beyond multiple sclerosis, which may broaden its use in clinical practice.
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Affiliation(s)
| | - Xavier Montalban
- Servei de Neurologia-Neuroimmunologia, Centre d'Esclerosi Múltiple de Catalunya (Cemcat), Hospital Universitario Vall d'Hebron, Barcelona, Spain.,St. Michael's Hospital, University of Toronto, Toronto, Canada
| | - Hans-Peter Hartung
- Department of Neurology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany.
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Ladi-Seyedian SS, Nabavizadeh B, Sharifi-Rad L, Kajbafzadeh AM. Pharmacological treatments available for the management of underactive bladder in neurological conditions. Expert Rev Clin Pharmacol 2017; 11:193-204. [DOI: 10.1080/17512433.2018.1411801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Seyedeh-Sanam Ladi-Seyedian
- Pediatric Urology and Regenerative Medicine Research Center, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Behnam Nabavizadeh
- Pediatric Urology and Regenerative Medicine Research Center, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Lida Sharifi-Rad
- Pediatric Urology and Regenerative Medicine Research Center, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran
- Department of Physical Therapy, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Abdol-Mohammad Kajbafzadeh
- Pediatric Urology and Regenerative Medicine Research Center, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran
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Hassan S, Ejaz SA, Saeed A, Shehzad M, Ullah Khan S, Lecka J, Sévigny J, Shabir G, Iqbal J. 4-Aminopyridine based amide derivatives as dual inhibitors of tissue non-specific alkaline phosphatase and ecto-5'-nucleotidase with potential anticancer activity. Bioorg Chem 2017; 76:237-248. [PMID: 29197225 DOI: 10.1016/j.bioorg.2017.11.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 11/04/2017] [Accepted: 11/17/2017] [Indexed: 12/19/2022]
Abstract
Ecto-nucleotidase members i.e., ecto-5'-nucleotidase and alkaline phosphatase, hydrolyze extracellular nucleotides and play an important role in purinergic signaling. Their overexpression are implicated in a variety of pathological states, including immunological diseases, bone mineralization, vascular calcification and cancer, and thus they represent an emerging drug targets. In order to design potent and selective inhibitors, new derivatives of 4-aminopyridine have been synthesized (10a-10m) and their structures were established on the basis of spectral data. The effect of nature and position of substituent was interestingly observed and justified on the basis of their detailed structure activity relationships (SARs) against both families of ecto-nucleotidase. Compound 10a displayed significant inhibition (IC50 ± SEM = 0.25 ± 0.05 µM) that was found ≈168 fold more potent as compared to previously reported inhibitor suramin (IC50 ± SEM = 42.1 ± 7.8 µM). This compound exhibited 6 times more selectivity towards h-TNAP over h-e5'NT. The anticancer potential and mechanism were also established using cell viability assay, flow cytometric analysis and nuclear staining. Molecular docking studies were also carried out to gain insight into the binding interaction of potent compounds within the respective enzyme pockets and herring-sperm DNA.
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Affiliation(s)
- Sidra Hassan
- Centre for Advanced Drug Research, COMSATS Institute of Information Technology, 22060 Abbottabad, Pakistan
| | - Syeda Abida Ejaz
- Centre for Advanced Drug Research, COMSATS Institute of Information Technology, 22060 Abbottabad, Pakistan
| | - Aamer Saeed
- Department of Chemistry, Quaid-I-Azam University, 45320 Islamabad, Pakistan.
| | - Muddasar Shehzad
- Department of Chemistry, Quaid-I-Azam University, 45320 Islamabad, Pakistan
| | - Shafi Ullah Khan
- Centre for Advanced Drug Research, COMSATS Institute of Information Technology, 22060 Abbottabad, Pakistan
| | - Joanna Lecka
- Département de microbiologie-infectiologie et d'immunologie, Faculté de Médecine, Université Laval, Québec, QC, Canada; Centre de Recherche du CHU de Québec - Université Laval, Québec, QC, Canada
| | - Jean Sévigny
- Département de microbiologie-infectiologie et d'immunologie, Faculté de Médecine, Université Laval, Québec, QC, Canada; Centre de Recherche du CHU de Québec - Université Laval, Québec, QC, Canada
| | - Ghulam Shabir
- Department of Chemistry, Quaid-I-Azam University, 45320 Islamabad, Pakistan
| | - Jamshed Iqbal
- Centre for Advanced Drug Research, COMSATS Institute of Information Technology, 22060 Abbottabad, Pakistan.
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Jukkola P, Gu Y, Lovett-Racke AE, Gu C. Suppression of Inflammatory Demyelinaton and Axon Degeneration through Inhibiting Kv3 Channels. Front Mol Neurosci 2017; 10:344. [PMID: 29123469 PMCID: PMC5662905 DOI: 10.3389/fnmol.2017.00344] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 10/10/2017] [Indexed: 01/19/2023] Open
Abstract
The development of neuroprotective and repair strategies for treating progressive multiple sclerosis (MS) requires new insights into axonal injury. 4-aminopyridine (4-AP), a blocker of voltage-gated K+ (Kv) channels, is used in symptomatic treatment of progressive MS, but the underlying mechanism remains unclear. Here we report that deleting Kv3.1—the channel with the highest 4-AP sensitivity—reduces clinical signs in experimental autoimmune encephalomyelitis (EAE), a mouse model for MS. In Kv3.1 knockout (KO) mice, EAE lesions in sensory and motor tracts of spinal cord were markedly reduced, and radial astroglia were activated with increased expression of brain derived neurotrophic factor (BDNF). Kv3.3/Kv3.1 and activated BDNF receptors were upregulated in demyelinating axons in EAE and MS lesions. In spinal cord myelin coculture, BDNF treatment promoted myelination, and neuronal firing via altering channel expression. Therefore, suppressing Kv3.1 alters neural circuit activity, which may enhance BNDF signaling and hence protect axons from inflammatory insults.
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Affiliation(s)
- Peter Jukkola
- Biomedical Sciences Graduate Program, Wexner Medical Center, The Ohio State University, Columbus, OH, United States
| | - Yuanzheng Gu
- Department of Biological Chemistry and Pharmacology, Wexner Medical Center, The Ohio State University, Columbus, OH, United States
| | - Amy E Lovett-Racke
- Department of Microbial Infection and Immunity, Wexner Medical Center, The Ohio State University, Columbus, OH, United States
| | - Chen Gu
- Biomedical Sciences Graduate Program, Wexner Medical Center, The Ohio State University, Columbus, OH, United States.,Department of Biological Chemistry and Pharmacology, Wexner Medical Center, The Ohio State University, Columbus, OH, United States
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Schoser B, Eymard B, Datt J, Mantegazza R. Lambert–Eaton myasthenic syndrome (LEMS): a rare autoimmune presynaptic disorder often associated with cancer. J Neurol 2017; 264:1854-1863. [DOI: 10.1007/s00415-017-8541-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 06/06/2017] [Accepted: 06/07/2017] [Indexed: 10/19/2022]
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Ciallella JR, Reaume AG. In vivo phenotypic screening: clinical proof of concept for a drug repositioning approach. DRUG DISCOVERY TODAY. TECHNOLOGIES 2017. [PMID: 28647085 DOI: 10.1016/j.ddtec.2017.04.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In vivo phenotypic screening and drug repositioning are strategies developed as alternatives to underperforming hypothesis-driven molecular target based drug discovery efforts. This article reviews examples of drugs identified by phenotypic observations and describes the use of the theraTRACE®in vivo screening platform for finding and developing new indications for discontinued clinical compounds. Clinical proof-of-concept for the platform is exemplified by MLR-1023, a repositioned compound that has recently shown significant clinical efficacy in Type 2 diabetes patients. These findings validate an in vivo screening approach for drug development and underscore the importance of alternatives to target and mechanism based strategies that have failed to produce adequate numbers of new medicines.
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43
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Dalfampridine: Review on its recent development for symptomatic improvement in patients with multiple sclerosis. ARAB J CHEM 2016. [DOI: 10.1016/j.arabjc.2012.03.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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44
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Kasatkina LA. 4-Аminopyridine sequesters intracellular Ca 2+ which triggers exocytosis in excitable and non-excitable cells. Sci Rep 2016; 6:34749. [PMID: 27703262 PMCID: PMC5050491 DOI: 10.1038/srep34749] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 09/16/2016] [Indexed: 12/19/2022] Open
Abstract
4-aminopyridine is commonly used to stimulate neurotransmitter release resulting from sustained plasma membrane depolarization and Ca2+-influx from the extracellular space. This paper elucidated unconventional mechanism of 4-aminopyridine-stimulated glutamate release from neurons and non-neuronal cells which proceeds in the absence of external Ca2+. In brain nerve terminals, primary neurons and platelets 4-aminopyridine induced the exocytotic release of glutamate that was independent of external Ca2+ and was triggered by the sequestration of Ca2+ from intracellular stores. The initial level of 4-aminopyridine-stimulated glutamate release from neurons in the absence or presence of external Ca2+ was subequal and the difference was predominantly associated with subsequent tonic release of glutamate in Ca2+-supplemented medium. The increase in [Ca2+]i and the secretion of glutamate stimulated by 4-aminopyridine in Ca2+-free conditions have resulted from Ca2+ efflux from endoplasmic reticulum and were abolished by intracellular free Ca2+ chelator BAPTA. This suggests that Ca2+ sequestration plays a profound role in the 4-aminopyridine-mediated stimulation of excitable and non-excitable cells. 4-Aminopyridine combines the properties of depolarizing agent with the ability to sequester intracellular Ca2+. The study unmasks additional mechanism of action of 4-aminopyridine, an active substance of drugs for treatment of multiple sclerosis and conditions related to reduced Ca2+ efflux from intracellular stores.
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Affiliation(s)
- Ludmila A Kasatkina
- The Department of Neurochemistry, Palladin Institute of Biochemistry, NAS of Ukraine 9, Leontovicha Street, Kyiv, 01030, Ukraine
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45
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Protein partners of the calcium channel β subunit highlight new cellular functions. Biochem J 2016; 473:1831-44. [DOI: 10.1042/bcj20160125] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 03/15/2016] [Indexed: 12/21/2022]
Abstract
Calcium plays a key role in cell signalling by its intervention in a wide range of physiological processes. Its entry into cells occurs mainly via voltage-gated calcium channels (VGCC), which are found not only in the plasma membrane of excitable cells but also in cells insensitive to electrical signals. VGCC are composed of different subunits, α1, β, α2δ and γ, among which the cytosolic β subunit (Cavβ) controls the trafficking of the channel to the plasma membrane, its regulation and its gating properties. For many years, these were the main functions associated with Cavβ. However, a growing number of proteins have been found to interact with Cavβ, emphasizing the multifunctional role of this versatile protein. Interestingly, some of the newly assigned functions of Cavβ are independent of its role in the regulation of VGCC, and thus further increase its functional roles. Based on the identity of Cavβ protein partners, this review emphasizes the diverse cellular functions of Cavβ and summarizes both past findings as well as recent progress in the understanding of VGCC.
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Haghdoost-Yazdi H, Piri H, Faraji A, Fraidouni N, Dargahi T, Mahmudi M, Alipour Heidari M. Pretreatment with potassium channel blockers of 4-aminopyridine and tetraethylammonium attenuates behavioural symptoms of Parkinsonism induced by intrastriatal injection of 6-hydroxydopamine; the role of lipid peroxidation. Neurol Res 2016; 38:294-300. [DOI: 10.1080/01616412.2015.1114290] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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47
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Evoli A, Alboini PE, Damato V, Iorio R. 3,4-Diaminopyridine may improve myasthenia gravis with MuSK antibodies. Neurology 2016; 86:1070-1. [DOI: 10.1212/wnl.0000000000002466] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 10/12/2015] [Indexed: 11/15/2022] Open
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Aging-Related Hyperexcitability in CA3 Pyramidal Neurons Is Mediated by Enhanced A-Type K+ Channel Function and Expression. J Neurosci 2015; 35:13206-18. [PMID: 26400949 DOI: 10.1523/jneurosci.0193-15.2015] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aging-related impairments in hippocampus-dependent cognition have been attributed to maladaptive changes in the functional properties of pyramidal neurons within the hippocampal subregions. Much evidence has come from work on CA1 pyramidal neurons, with CA3 pyramidal neurons receiving comparatively less attention despite its age-related hyperactivation being postulated to interfere with spatial processing in the hippocampal circuit. Here, we use whole-cell current-clamp to demonstrate that aged rat (29-32 months) CA3 pyramidal neurons fire significantly more action potentials (APs) during theta-burst frequency stimulation and that this is associated with faster AP repolarization (i.e., narrower AP half-widths and enlarged fast afterhyperpolarization). Using a combination of patch-clamp physiology, pharmacology, Western blot analyses, immunohistochemistry, and array tomography, we demonstrate that these faster AP kinetics are mediated by enhanced function and expression of Kv4.2/Kv4.3 A-type K(+) channels, particularly within the perisomatic compartment, of CA3 pyramidal neurons. Thus, our study indicates that inhibition of these A-type K(+) channels can restore the intrinsic excitability properties of aged CA3 pyramidal neurons to a young-like state. Significance statement: Age-related learning deficits have been attributed, in part, to altered hippocampal pyramidal neuronal function with normal aging. Much evidence has come from work on CA1 neurons, with CA3 neurons receiving comparatively less attention despite its age-related hyperactivation being postulated to interfere with spatial processing. Hence, we conducted a series of experiments to identify the cellular mechanisms that underlie the hyperexcitability reported in the CA3 region. Contrary to CA1 neurons, we demonstrate that postburst afterhyperpolarization is not altered with aging and that aged CA3 pyramidal neurons are able to fire significantly more action potentials and that this is associated with faster action potential repolarization through enhanced expression of Kv4.2/Kv4.3 A-type K(+) channels, particularly within the cell bodies of CA3 pyramidal neurons.
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49
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Zhou MH, Bavencoffe A, Pan HL. Molecular Basis of Regulating High Voltage-Activated Calcium Channels by S-Nitrosylation. J Biol Chem 2015; 290:30616-23. [PMID: 26507659 DOI: 10.1074/jbc.m115.685206] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Indexed: 12/18/2022] Open
Abstract
Nitric oxide (NO) is involved in a variety of physiological processes, such as vasoregulation and neurotransmission, and has a complex role in the regulation of pain transduction and synaptic transmission. We have shown previously that NO inhibits high voltage-activated Ca(2+) channels in primary sensory neurons and excitatory synaptic transmission in the spinal dorsal horn. However, the molecular mechanism involved in this inhibitory action remains unclear. In this study, we investigated the role of S-nitrosylation in the NO regulation of high voltage-activated Ca(2+) channels. The NO donor S-nitroso-N-acetyl-DL-penicillamine (SNAP) rapidly reduced N-type currents when Cav2.2 was coexpressed with the Cavβ1 or Cavβ3 subunits in HEK293 cells. In contrast, SNAP only slightly inhibited P/Q-type and L-type currents reconstituted with various Cavβ subunits. SNAP caused a depolarizing shift in voltage-dependent N-type channel activation, but it had no effect on Cav2.2 protein levels on the membrane surface. The inhibitory effect of SNAP on N-type currents was blocked by the sulfhydryl-specific modifying reagent methanethiosulfonate ethylammonium. Furthermore, the consensus motifs of S-nitrosylation were much more abundant in Cav2.2 than in Cav1.2 and Cav2.1. Site-directed mutagenesis studies showed that Cys-805, Cys-930, and Cys-1045 in the II-III intracellular loop, Cys-1835 and Cys-2145 in the C terminus of Cav2.2, and Cys-346 in the Cavβ3 subunit were nitrosylation sites mediating NO sensitivity of N-type channels. Our findings demonstrate that the consensus motifs of S-nitrosylation in cytoplasmically accessible sites are critically involved in post-translational regulation of N-type Ca(2+) channels by NO. S-Nitrosylation mediates the feedback regulation of N-type channels by NO.
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Affiliation(s)
- Meng-Hua Zhou
- From the Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience and Pain Research, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Alexis Bavencoffe
- From the Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience and Pain Research, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Hui-Lin Pan
- From the Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience and Pain Research, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
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Kadow BT, Tyagi P, Chermansky CJ. Neurogenic Causes of Detrusor Underactivity. CURRENT BLADDER DYSFUNCTION REPORTS 2015; 10:325-331. [PMID: 26715948 DOI: 10.1007/s11884-015-0331-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Detrusor underactivity (DU) is a poorly understood dysfunction of the lower urinary tract which arises from multiple etiologies. Symptoms of DU are non-specific, and a pressure-flow urodynamic study is necessary to differentiate DU from other conditions such as overactive bladder (OAB) or bladder outlet obstruction (BOO). The prevalence of DU ranges from 10-48%, and DU is most prevalent in elderly males. The pathophysiology underlying DU can be from both neurogenic and non-neurogenic causes. In this article, we review the neurogenic causes of detrusor underactivity, including diabetic bladder dysfunction, spinal cord injury, multiple sclerosis, Parkinson's disease, cerebrovascular accident, traumatic brain injury, and Fowler's syndrome. As knowledge about the underlying causes of DU advances, there have been several potential therapeutic approaches proposed to help those who suffer from this condition.
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Affiliation(s)
- Brian T Kadow
- Department of Urology, University of Pittsburgh Medical Center, Pittsburgh, PA, U.S
| | - Pradeep Tyagi
- Department of Urology, University of Pittsburgh Medical Center, Pittsburgh, PA, U.S
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