1
|
Dwivedi R, Kaushik M, Tripathi M, Dada R, Tiwari P. Unraveling the genetic basis of epilepsy: Recent advances and implications for diagnosis and treatment. Brain Res 2024; 1843:149120. [PMID: 39032529 DOI: 10.1016/j.brainres.2024.149120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2024] [Revised: 07/05/2024] [Accepted: 07/08/2024] [Indexed: 07/23/2024]
Abstract
Epilepsy, affecting approximately 1% of the global population, manifests as recurring seizures and is heavily influenced by genetic factors. Recent advancements in genetic technologies have revolutionized our understanding of epilepsy's genetic landscape. Key studies, such as the discovery of mutations in ion channels (e.g., SCN1A and SCN2A), neurotransmitter receptors (e.g., GABRA1), and synaptic proteins (e.g., SYNGAP1, KCNQ2), have illuminated critical pathways underlying epilepsy susceptibility and pathogenesis. Genome-wide association studies (GWAS) have identified specific genetic variations linked to epilepsy risk, such as variants near SCN1A and PCDH7, enhancing diagnostic accuracy and enabling personalized treatment strategies. Moreover, epigenetic mechanisms, including DNA methylation (e.g., MBD5), histone modifications (e.g., HDACs), and non-coding RNAs (e.g., miR-134), play pivotal roles in altering gene expression and synaptic plasticity, contributing to epileptogenesis. These discoveries offer promising avenues for therapeutic interventions aimed at improving outcomes for epilepsy patients. Genetic testing has become essential in clinical practice, facilitating precise diagnosis and tailored management approaches based on individual genetic profiles. Furthermore, insights into epigenetic regulation suggest novel therapeutic targets for developing more effective epilepsy treatments. In summary, this review highlights significant progress in understanding the genetic and epigenetic foundations of epilepsy. By integrating findings from key studies and specifying genes involved in epigenetic modifications, we underscore the potential for advanced therapeutic strategies in this complex neurological disorder, emphasizing the importance of personalized medicine approaches in epilepsy management.
Collapse
Affiliation(s)
- Rekha Dwivedi
- Department of Neurology, All India Institute of Medical Sciences (AIIMS), New Delhi 110029, India
| | - Meenakshi Kaushik
- Department of Anatomy, All India Institute of Medical Sciences (AIIMS), New Delhi 110029, India
| | - Manjari Tripathi
- Department of Neurology, All India Institute of Medical Sciences (AIIMS), New Delhi 110029, India
| | - Rima Dada
- Department of Anatomy, All India Institute of Medical Sciences (AIIMS), New Delhi 110029, India
| | - Prabhakar Tiwari
- Department of Anatomy, All India Institute of Medical Sciences (AIIMS), New Delhi 110029, India.
| |
Collapse
|
2
|
Müller P, Draguhn A, Egorov AV. Persistent sodium currents in neurons: potential mechanisms and pharmacological blockers. Pflugers Arch 2024:10.1007/s00424-024-02980-7. [PMID: 38967655 DOI: 10.1007/s00424-024-02980-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2024] [Revised: 06/07/2024] [Accepted: 06/11/2024] [Indexed: 07/06/2024]
Abstract
Persistent sodium current (INaP) is an important activity-dependent regulator of neuronal excitability. It is involved in a variety of physiological and pathological processes, including pacemaking, prolongation of sensory potentials, neuronal injury, chronic pain and diseases such as epilepsy and amyotrophic lateral sclerosis. Despite its importance, neither the molecular basis nor the regulation of INaP are sufficiently understood. Of particular significance is a solid knowledge and widely accepted consensus about pharmacological tools for analysing the function of INaP and for developing new therapeutic strategies. However, the literature on INaP is heterogeneous, with varying definitions and methodologies used across studies. To address these issues, we provide a systematic review of the current state of knowledge on INaP, with focus on mechanisms and effects of this current in the central nervous system. We provide an overview of the specificity and efficacy of the most widely used INaP blockers: amiodarone, cannabidiol, carbamazepine, cenobamate, eslicarbazepine, ethosuximide, gabapentin, GS967, lacosamide, lamotrigine, lidocaine, NBI-921352, oxcarbazepine, phenytoine, PRAX-562, propofol, ranolazine, riluzole, rufinamide, topiramate, valproaic acid and zonisamide. We conclude that there is strong variance in the pharmacological effects of these drugs, and in the available information. At present, GS967 and riluzole can be regarded bona fide INaP blockers, while phenytoin and lacosamide are blockers that only act on the slowly inactivating component of sodium currents.
Collapse
Affiliation(s)
- Peter Müller
- Department Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tuebingen , Hoppe-Seyler-Straße 3, 72076, Tübingen, Germany.
| | - Andreas Draguhn
- Institute for Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Im Neuenheimer Feld 326, 69120, Heidelberg, Germany
| | - Alexei V Egorov
- Institute for Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Im Neuenheimer Feld 326, 69120, Heidelberg, Germany
| |
Collapse
|
3
|
King DR, Demirtas M, Tarasov M, Struckman HL, Meng X, Nassal D, Moise N, Miller A, Min D, Soltisz AM, Anne MNK, Alves Dias PA, Wagnon JL, Weinberg SH, Hund TJ, Veeraraghavan R, Radwański PB. Cardiac-Specific Deletion of Scn8a Mitigates Dravet Syndrome-Associated Sudden Death in Adults. JACC Clin Electrophysiol 2024; 10:829-842. [PMID: 38430092 PMCID: PMC11285447 DOI: 10.1016/j.jacep.2024.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 12/27/2023] [Accepted: 01/03/2024] [Indexed: 03/03/2024]
Abstract
BACKGROUND Sudden unexpected death in epilepsy (SUDEP) is a fatal complication experienced by otherwise healthy epilepsy patients. Dravet syndrome (DS) is an inherited epileptic disorder resulting from loss of function of the voltage-gated sodium channel, NaV 1.1, and is associated with particularly high SUDEP risk. Evidence is mounting that NaVs abundant in the brain also occur in the heart, suggesting that the very molecular mechanisms underlying epilepsy could also precipitate cardiac arrhythmias and sudden death. Despite marked reduction of NaV 1.1 functional expression in DS, pathogenic late sodium current (INa,L) is paradoxically increased in DS hearts. However, the mechanisms by which DS directly impacts the heart to promote sudden death remain unclear. OBJECTIVES In this study, the authors sought to provide evidence implicating remodeling of Na+ - and Ca2+ -handling machinery, including NaV 1.6 and Na+/Ca2+exchanger (NCX) within transverse (T)-tubules in DS-associated arrhythmias. METHODS The authors undertook scanning ion conductance microscopy (SICM)-guided patch clamp, super-resolution microscopy, confocal Ca2+ imaging, and in vivo electrocardiography studies in Scn1a haploinsufficient murine model of DS. RESULTS DS promotes INa,L in T-tubular nanodomains, but not in other subcellular regions. Consistent with increased NaV activity in these regions, super-resolution microscopy revealed increased NaV 1.6 density near Ca2+release channels, the ryanodine receptors (RyR2) and NCX in DS relative to WT hearts. The resulting INa,L in these regions promoted aberrant Ca2+ release, leading to ventricular arrhythmias in vivo. Cardiac-specific deletion of NaV 1.6 protects adult DS mice from increased T-tubular late NaV activity and the resulting arrhythmias, as well as sudden death. CONCLUSIONS These data demonstrate that NaV 1.6 undergoes remodeling within T-tubules of adult DS hearts serving as a substrate for Ca2+ -mediated cardiac arrhythmias and may be a druggable target for the prevention of SUDEP in adult DS subjects.
Collapse
Affiliation(s)
- D Ryan King
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA; Division of Outcomes and Translational Sciences, College of Pharmacy, The Ohio State University, Columbus, Ohio, USA
| | - Mustafa Demirtas
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA; Division of Outcomes and Translational Sciences, College of Pharmacy, The Ohio State University, Columbus, Ohio, USA
| | - Mikhail Tarasov
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA; Division of Outcomes and Translational Sciences, College of Pharmacy, The Ohio State University, Columbus, Ohio, USA
| | - Heather L Struckman
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA; Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Xiaolei Meng
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA; Division of Outcomes and Translational Sciences, College of Pharmacy, The Ohio State University, Columbus, Ohio, USA
| | - Drew Nassal
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA; Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Nicolae Moise
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA; Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Alec Miller
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA; Division of Outcomes and Translational Sciences, College of Pharmacy, The Ohio State University, Columbus, Ohio, USA
| | - Dennison Min
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA; Division of Outcomes and Translational Sciences, College of Pharmacy, The Ohio State University, Columbus, Ohio, USA
| | - Andrew M Soltisz
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA; Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Midhun N K Anne
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA; Department of Neuroscience, College of Medicine, The Ohio State University, Columbus, Ohio, USA
| | - Patrícia A Alves Dias
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA; Division of Outcomes and Translational Sciences, College of Pharmacy, The Ohio State University, Columbus, Ohio, USA; Department of Pharmacology and Toxicology, Faculty of Pharmacy, Charles University, Akademika Heyrovského Hradec Králové, Czech Republic
| | - Jacy L Wagnon
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA; Department of Neuroscience, College of Medicine, The Ohio State University, Columbus, Ohio, USA
| | - Seth H Weinberg
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA; Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Thomas J Hund
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA; Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA; Department of Internal Medicine, Division of Cardiovascular Medicine, College of Medicine, The Ohio State University, Columbus, Ohio, USA
| | - Rengasayee Veeraraghavan
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA; Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Przemysław B Radwański
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA; Division of Outcomes and Translational Sciences, College of Pharmacy, The Ohio State University, Columbus, Ohio, USA.
| |
Collapse
|
4
|
Jansen NA, Cestèle S, Marco SS, Schenke M, Stewart K, Patel J, Tolner EA, Brunklaus A, Mantegazza M, van den Maagdenberg AMJM. Brainstem depolarization-induced lethal apnea associated with gain-of-function SCN1AL263V is prevented by sodium channel blockade. Proc Natl Acad Sci U S A 2024; 121:e2309000121. [PMID: 38547067 PMCID: PMC10998578 DOI: 10.1073/pnas.2309000121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 02/21/2024] [Indexed: 04/02/2024] Open
Abstract
Apneic events are frightening but largely benign events that often occur in infants. Here, we report apparent life-threatening apneic events in an infant with the homozygous SCN1AL263V missense mutation, which causes familial hemiplegic migraine type 3 in heterozygous family members, in the absence of epilepsy. Observations consistent with the events in the infant were made in an Scn1aL263V knock-in mouse model, in which apnea was preceded by a large brainstem DC-shift, indicative of profound brainstem depolarization. The L263V mutation caused gain of NaV1.1 function effects in transfected HEK293 cells. Sodium channel blockade mitigated the gain-of-function characteristics, rescued lethal apnea in Scn1aL263V mice, and decreased the frequency of severe apneic events in the patient. Hence, this study shows that SCN1AL263V can cause life-threatening apneic events, which in a mouse model were caused by profound brainstem depolarization. In addition to being potentially relevant to sudden infant death syndrome pathophysiology, these data indicate that sodium channel blockers may be considered therapeutic for apneic events in patients with these and other gain-of-function SCN1A mutations.
Collapse
Affiliation(s)
- Nico A. Jansen
- Department of Human Genetics, Leiden University Medical Center, Leiden2333 ZC, The Netherlands
| | - Sandrine Cestèle
- Université Côte d’Azur, Valbonne-Sophia Antipolis06560, France
- Institute of Molecular and Cellular Pharmacology, Valbonne-Sophia Antipolis06560, France
| | - Silvia Sanchez Marco
- Department of Paediatric Neurology, Bristol Royal Hospital for Children, University Hospitals Bristol, BristolBS2 8BJ, United Kingdom
| | - Maarten Schenke
- Department of Human Genetics, Leiden University Medical Center, Leiden2333 ZC, The Netherlands
| | - Kirsty Stewart
- West of Scotland Genetic Services, Queen Elizabeth University Hospital, GlasgowG51 4TF, United Kingdom
| | - Jayesh Patel
- Department of Paediatric Neurology, Bristol Royal Hospital for Children, University Hospitals Bristol, BristolBS2 8BJ, United Kingdom
| | - Else A. Tolner
- Department of Human Genetics, Leiden University Medical Center, Leiden2333 ZC, The Netherlands
- Department of Neurology, Leiden University Medical Center, Leiden2333 ZA, The Netherlands
| | - Andreas Brunklaus
- The Paediatric Neurosciences Research Group, Royal Hospital for Children, GlasgowG51 4TF, United Kingdom
- School of Health and Wellbeing, University of Glasgow, GlasgowG12 8TB, United Kingdom
| | - Massimo Mantegazza
- Université Côte d’Azur, Valbonne-Sophia Antipolis06560, France
- Institute of Molecular and Cellular Pharmacology, Valbonne-Sophia Antipolis06560, France
- Inserm, Valbonne-Sophia Antipolis06560, France
| | - Arn M. J. M. van den Maagdenberg
- Department of Human Genetics, Leiden University Medical Center, Leiden2333 ZC, The Netherlands
- Department of Neurology, Leiden University Medical Center, Leiden2333 ZA, The Netherlands
| |
Collapse
|
5
|
Fan HC, Yang MT, Lin LC, Chiang KL, Chen CM. Clinical and Genetic Features of Dravet Syndrome: A Prime Example of the Role of Precision Medicine in Genetic Epilepsy. Int J Mol Sci 2023; 25:31. [PMID: 38203200 PMCID: PMC10779156 DOI: 10.3390/ijms25010031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 12/14/2023] [Accepted: 12/17/2023] [Indexed: 01/12/2024] Open
Abstract
Dravet syndrome (DS), also known as severe myoclonic epilepsy of infancy, is a rare and drug-resistant form of developmental and epileptic encephalopathies, which is both debilitating and challenging to manage, typically arising during the first year of life, with seizures often triggered by fever, infections, or vaccinations. It is characterized by frequent and prolonged seizures, developmental delays, and various other neurological and behavioral impairments. Most cases result from pathogenic mutations in the sodium voltage-gated channel alpha subunit 1 (SCN1A) gene, which encodes a critical voltage-gated sodium channel subunit involved in neuronal excitability. Precision medicine offers significant potential for improving DS diagnosis and treatment. Early genetic testing enables timely and accurate diagnosis. Advances in our understanding of DS's underlying genetic mechanisms and neurobiology have enabled the development of targeted therapies, such as gene therapy, offering more effective and less invasive treatment options for patients with DS. Targeted and gene therapies provide hope for more effective and personalized treatments. However, research into novel approaches remains in its early stages, and their clinical application remains to be seen. This review addresses the current understanding of clinical DS features, genetic involvement in DS development, and outcomes of novel DS therapies.
Collapse
Affiliation(s)
- Hueng-Chuen Fan
- Department of Pediatrics, Tungs’ Taichung Metroharbor Hospital, Wuchi, Taichung 435, Taiwan;
- Department of Rehabilitation, Jen-Teh Junior College of Medicine, Nursing and Management, Miaoli 356, Taiwan
- Department of Life Sciences, Agricultural Biotechnology Center, National Chung Hsing University, Taichung 402, Taiwan
| | - Ming-Tao Yang
- Department of Pediatrics, Far Eastern Memorial Hospital, New Taipei City 220, Taiwan;
- Department of Chemical Engineering and Materials Science, Yuan Ze University, Taoyuan 320, Taiwan
| | - Lung-Chang Lin
- Department of Pediatrics, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan;
- Department of Pediatrics, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 807, Taiwan
| | - Kuo-Liang Chiang
- Department of Pediatric Neurology, Kuang-Tien General Hospital, Taichung 433, Taiwan;
- Department of Nutrition, Hungkuang University, Taichung 433, Taiwan
| | - Chuan-Mu Chen
- Department of Life Sciences, Agricultural Biotechnology Center, National Chung Hsing University, Taichung 402, Taiwan
- The iEGG and Animal Biotechnology Center, and Rong Hsing Research Center for Translational Medicine, National Chung Hsing University, Taichung 402, Taiwan
| |
Collapse
|
6
|
Anderson LL, Everett‐Morgan D, Petkova SP, Silverman JL, Arnold JC. Ictal vocalizations in the Scn1a +/- mouse model of Dravet syndrome. Epilepsia Open 2023; 8:776-784. [PMID: 36811143 PMCID: PMC10472354 DOI: 10.1002/epi4.12715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 02/18/2023] [Indexed: 02/24/2023] Open
Abstract
OBJECTIVE Ictal vocalizations have shown diagnostic utility in epilepsy patients. Audio recordings of seizures have also been used for seizure detection. The present study aimed to determine whether generalized tonic-clonic seizures in the Scn1a+/- mouse model of Dravet syndrome are associated with either audible mouse squeaks or ultrasonic vocalizations. METHODS Acoustic recordings were captured from group-housed Scn1a+/- mice undergoing video-monitoring to quantify spontaneous seizure frequency. We generated audio clips (n = 129) during a generalized tonic-clonic seizure (GTCS) that included 30 seconds immediately prior to the GTCS (preictal) and 30 seconds following the conclusion of the seizure (postictal). Nonseizure clips (n = 129) were also exported from the acoustic recordings. A blinded reviewer manually reviewed the audio clips, and vocalizations were identified as either an audible (<20 kHz) mouse squeak or ultrasonic (>20 kHz). RESULTS Spontaneous GTCS in Scn1a+/- mice were associated with a significantly higher number of total vocalizations. The number of audible mouse squeaks was significantly greater with GTCS activity. Nearly all (98%) the seizure clips contained ultrasonic vocalizations, whereas ultrasonic vocalizations were present in only 57% of nonseizure clips. The ultrasonic vocalizations emitted in the seizure clips were at a significantly higher frequency and were nearly twice as long in duration as those emitted in the nonseizure clips. Audible mouse squeaks were primarily emitted during the preictal phase. The greatest number of ultrasonic vocalizations was detected during the ictal phase. SIGNIFICANCE Our study shows that ictal vocalizations are exhibited by Scn1a+/- mice. Quantitative audio analysis could be developed as a seizure detection tool for the Scn1a+/- mouse model of Dravet syndrome.
Collapse
Affiliation(s)
- Lyndsey L. Anderson
- Lambert Initiative for Cannabinoid TherapeuticsThe University of SydneyCamperdownNew South WalesAustralia
- Discipline of Pharmacology, School of PharmacyFaculty of Medicine and Health, The University of SydneyCamperdownNew South WalesAustralia
- Brain and Mind CentreThe University of SydneyCamperdownNew South WalesAustralia
| | - Declan Everett‐Morgan
- Lambert Initiative for Cannabinoid TherapeuticsThe University of SydneyCamperdownNew South WalesAustralia
| | - Stela P. Petkova
- Department of Psychiatry and Behavioral Sciences, MIND Institute, School of MedicineUniversity of CaliforniaDavisCaliforniaUSA
| | - Jill L. Silverman
- Department of Psychiatry and Behavioral Sciences, MIND Institute, School of MedicineUniversity of CaliforniaDavisCaliforniaUSA
| | - Jonathon C. Arnold
- Lambert Initiative for Cannabinoid TherapeuticsThe University of SydneyCamperdownNew South WalesAustralia
- Discipline of Pharmacology, School of PharmacyFaculty of Medicine and Health, The University of SydneyCamperdownNew South WalesAustralia
- Brain and Mind CentreThe University of SydneyCamperdownNew South WalesAustralia
| |
Collapse
|
7
|
Makridis KL, Friedo AL, Kellinghaus C, Losch FP, Schmitz B, Boßelmann C, Kaindl AM. Successful treatment of adult Dravet syndrome patients with cenobamate. Epilepsia 2022; 63:e164-e171. [PMID: 36176237 DOI: 10.1111/epi.17427] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 09/26/2022] [Accepted: 09/28/2022] [Indexed: 01/11/2023]
Abstract
Dravet syndrome (DS) is a rare, drug-resistant, severe developmental and epileptic encephalopathy caused by pathogenic variants in the α subunit of the voltage-gated sodium channel gene SCN1A. Hyperexcitability in DS results from loss of function in inhibitory interneurons. Thus sodium channel blockers are usually contraindicated in patients with DS as they may lead to disease aggravation. Cenobamate (CNB) is a novel antiseizure medication (ASM) with promising rates of seizure freedom in patients with focal-onset, drug-resistant epilepsy. CNB blocks persistent sodium currents by promoting the inactive states of sodium channels. In a multi-center study, we analyzed retrospectively the effect of an add-on therapy of CNB in adult patients with DS. We report four adult patients with DS in whom the use of CNB resulted in a significant seizure reduction of more than 80%, with a follow-up of up to 542 days. CNB was the first drug in these patients that resulted in a long-lasting and significant seizure reduction. No severe adverse events occurred. We highlight CNB as an ASM that may lead to a clinically meaningful reduction of seizure frequency in adult patients with DS. It is unclear, however, if all patients with DS benefit, requiring further investigation and functional experiments.
Collapse
Affiliation(s)
- Konstantin L Makridis
- Department of Pediatric Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Center for Chronically Sick Children, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Institute of Cell and Neurobiology, Charité - Universitätsmedizin Berlin, Berlin, Germany.,German Epilepsy Center for Children and Adolescents, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Anna-Lena Friedo
- Epilepsy Center Berlin-Brandenburg, Epilepsieklinik Tabor, Bernau, Germany
| | | | | | - Bettina Schmitz
- Department of Neurology, Vivantes Humboldt-Klinikum, Berlin, Germany
| | - Christian Boßelmann
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Angela M Kaindl
- Department of Pediatric Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Center for Chronically Sick Children, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Institute of Cell and Neurobiology, Charité - Universitätsmedizin Berlin, Berlin, Germany.,German Epilepsy Center for Children and Adolescents, Charité - Universitätsmedizin Berlin, Berlin, Germany
| |
Collapse
|
8
|
Suvekbala V, Ramachandran H, Veluchamy A, Mascarenhas MAB, Ramprasath T, Nair MKC, Garikipati VNS, Gundamaraju R, Subbiah R. The Promising Epigenetic Regulators for Refractory Epilepsy: An Adventurous Road Ahead. Neuromolecular Med 2022:10.1007/s12017-022-08723-0. [DOI: 10.1007/s12017-022-08723-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 07/13/2022] [Indexed: 10/14/2022]
|
9
|
Riva A, D'Onofrio G, Amadori E, Tripodi D, Balagura G, Iurilli V, Vari MS, Verrotti A, Striano P. Current and promising therapeutic options for Dravet syndrome. Expert Opin Pharmacother 2022; 23:1727-1736. [PMID: 36124778 DOI: 10.1080/14656566.2022.2127089] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION Dravet Syndrome (DS) is a developmental and epileptic encephalopathy carrying high-level psychobehavioral burdens. Although the disease has been known for almost 4 decades, and despite significant progress in the understanding of its physiopathology and natural course, the pharmacological treatment leaves patients and caregivers with significant unmet needs. This review provides a summary of the current and promising therapeutic options for DS. AREAS COVERED PubMed and ClinicalTrials.gov were screened using 'Dravet Syndrome' OR 'DS,' AND 'pharmacotherapy,' AND 'treatments.' Randomized clinical trials, structured reviews, and meta-analyses were selected for in-human application of well-known anti-seizure medications; while in-vivo experiments on models of DS were selected to evaluate the potential of new therapeutic strategies. EXPERT OPINION The search for new pharmacological treatment options is led by the need for care and defeat of the natural course of the disease, an aspect still largely neglected by the available therapeutic strategies. Yet, the last 6 years have led to a climate of increased interest and availability of clinical trials. Particularly, gene therapy could hopefully prevent DS evolution by directly relieving the specific genetic defect, although the possibility of off-target editing, and the uneasy administration route have still largely prevented its use.
Collapse
Affiliation(s)
- Antonella Riva
- Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy.,Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
| | - Gianluca D'Onofrio
- Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy.,Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
| | - Elisabetta Amadori
- Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy.,Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
| | - Domenico Tripodi
- Department of Medical, Oral and Biotechnological Sciences, University of Chieti, Genoa, Italy
| | - Ganna Balagura
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), Vrije Universiteit (VU), de Boelelaan, Amsterdam, Netherlands
| | | | - Maria Stella Vari
- Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | | | - Pasquale Striano
- Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy.,Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
| |
Collapse
|
10
|
Zavala-Tecuapetla C, Manjarrez-Marmolejo J, Ramírez-Jarquín JO, Rivera-Cerecedo CV. Eslicarbazepine, but Not Lamotrigine or Ranolazine, Shows Anticonvulsant Efficacy in Carbamazepine-Resistant Rats Developed by Window-Pentylenetetrazole Kindling. Brain Sci 2022; 12:brainsci12050629. [PMID: 35625015 PMCID: PMC9139658 DOI: 10.3390/brainsci12050629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 05/05/2022] [Accepted: 05/10/2022] [Indexed: 01/27/2023] Open
Abstract
Approximately 30% of epileptic patients develop Drug-Resistant Epilepsy. Based on evidence that shows a loss of efficacy in some sodium channel blocker antiseizure drugs in epilepsy, we focus our study on assessing the anticonvulsant efficacy of different sodium channel blockers on carbamazepine (CBZ)-resistant seizures generated using the window-pentylenetetrazole (PTZ) kindling model to verify whether one of these drugs presents some anticonvulsant effect that could have potential therapeutic use. Wistar rats were treated with a subthreshold dose of PTZ (35 mg/kg) three times/week. Fully kindled rats were then treated with a single dose of CBZ (40 mg/kg i.p.) at 2, 9 and 16 days after their last kindling stimulation to obtain CBZ-resistant rats. Right after, sodium channel blockers were tested for anticonvulsant action (lamotrigine, 30 mg/kg i.p.; eslicarbazepine, 150 or 300 mg/kg i.p.; ranolazine, 10, 20 or 40 mg/kg i.p.). Behavioral parameters included severity, latency or duration of convulsions. Our data showed for the first time directly that eslicarbazepine does have an anticonvulsant effect over CBZ-resistant seizures, while lamotrigine shows drug resistance and ranolazine demonstrates severe seizure worsening. It is of potential therapeutic relevance that eslicarbazepine could be useful to control seizures resistant to common sodium channel blockers such as CBZ.
Collapse
Affiliation(s)
- Cecilia Zavala-Tecuapetla
- Laboratory of Physiology of Reticular Formation, National Institute of Neurology and Neurosurgery, Insurgentes Sur 3877, La Fama, Mexico City 14269, Mexico;
- Correspondence:
| | - Joaquín Manjarrez-Marmolejo
- Laboratory of Physiology of Reticular Formation, National Institute of Neurology and Neurosurgery, Insurgentes Sur 3877, La Fama, Mexico City 14269, Mexico;
| | - Josué Orlando Ramírez-Jarquín
- Department of Molecular Neuropathology, Institute of Cellular Physiology, National Autonomous University of Mexico, Circuito Exterior s/n, Ciudad Universitaria, Mexico City 04510, Mexico;
| | - Claudia Verónica Rivera-Cerecedo
- Bioterium Academic Unit, Institute of Cellular Physiology, National Autonomous University of Mexico, Circuito Exterior s/n, Ciudad Universitaria, Mexico City 04510, Mexico;
| |
Collapse
|
11
|
Kahlig KM, Scott L, Hatch RJ, Griffin A, Martinez Botella G, Hughes ZA, Wittmann M. The novel persistent sodium current inhibitor PRAX-562 has potent anticonvulsant activity with improved protective index relative to standard of care sodium channel blockers. Epilepsia 2022; 63:697-708. [PMID: 35037706 PMCID: PMC9304232 DOI: 10.1111/epi.17149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 12/03/2021] [Accepted: 12/06/2021] [Indexed: 11/28/2022]
Abstract
OBJECTIVE This study investigates the effects of PRAX-562 on sodium current (INa ), intrinsic neuronal excitability, and protection from evoked seizures to determine whether a preferential persistent INa inhibitor would exhibit improved preclinical efficacy and tolerability compared to two standard voltage-gated sodium channel (NaV ) blockers. METHODS Inhibition of INa was characterized using patch clamp analysis. The effect on intrinsic excitability was measured using evoked action potentials recorded from hippocampal CA1 pyramidal neurons in mouse brain slices. Anticonvulsant activity was evaluated using the maximal electroshock seizure (MES) model, and tolerability was assessed by measuring spontaneous locomotor activity (sLMA). RESULTS PRAX-562 potently and preferentially inhibited persistent INa induced by ATX-II or the SCN8A mutation N1768D (half-maximal inhibitory concentration [IC50 ] = 141 and 75 nmol·L-1 , respectively) relative to peak INa tonic/resting block (60× preference). PRAX-562 also exhibited potent use-dependent block (31× preference to tonic block). This profile is considerably different from standard NaV blockers, including carbamazepine (CBZ; persistent INa IC50 = 77 500 nmol·L-1 , preference ratios of 30× [tonic block], less use-dependent block observed at various frequencies). In contrast to CBZ, PRAX-562 reduced neuronal intrinsic excitability with only a minor reduction in action potential amplitude. PRAX-562 (10 mg/kg po) completely prevented evoked seizures without affecting sLMA (MES unbound brain half-maximal efficacious concentration = 4.3 nmol·L-1 , sLMA half-maximal tolerated concentration = 69.7 nmol·L-1 , protective index [PI] = 16×). In contrast, CBZ and lamotrigine (LTG) had PIs of approximately 5.5×, with significant overlap between doses that were anticonvulsant and that reduced locomotor activity. SIGNIFICANCE PRAX-562 demonstrated robust preclinical anticonvulsant activity similar to CBZ but improved compared to LTG. PRAX-562 exhibited significantly improved preclinical tolerability compared with standard NaV blockers (CBZ and LTG), potentially due to the preference for persistent INa . Preferential targeting of persistent INa may represent a differentiated therapeutic option for diseases of hyperexcitability, where standard NaV blockers have demonstrated efficacy but poor tolerability.
Collapse
Affiliation(s)
| | - Liam Scott
- Praxis Precision Medicines, Boston, Massachusetts, USA
| | - Robert J Hatch
- Praxis Precision Medicines, Boston, Massachusetts, USA.,Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia
| | | | | | - Zoë A Hughes
- Praxis Precision Medicines, Boston, Massachusetts, USA
| | | |
Collapse
|
12
|
Xu C, Zhang Y, Gozal D, Carney P. Channelopathy of Dravet Syndrome and Potential Neuroprotective Effects of Cannabidiol. J Cent Nerv Syst Dis 2021; 13:11795735211048045. [PMID: 34992485 PMCID: PMC8724990 DOI: 10.1177/11795735211048045] [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] [Indexed: 12/19/2022] Open
Abstract
Dravet syndrome (DS) is a channelopathy, neurodevelopmental, epileptic encephalopathy characterized by seizures, developmental delay, and cognitive impairment that includes susceptibility to thermally induced seizures, spontaneous seizures, ataxia, circadian rhythm and sleep disorders, autistic-like behaviors, and premature death. More than 80% of DS cases are linked to mutations in genes which encode voltage-gated sodium channel subunits, SCN1A and SCN1B, which encode the Nav1.1α subunit and Nav1.1β1 subunit, respectively. There are other gene mutations encoding potassium, calcium, and hyperpolarization-activated cyclic nucleotide-gated (HCN) channels related to DS. One-third of patients have pharmacoresistance epilepsy. DS is unresponsive to standard therapy. Cannabidiol (CBD), a non-psychoactive phytocannabinoid present in Cannabis, has been introduced for treating DS because of its anticonvulsant properties in animal models and humans, especially in pharmacoresistant patients. However, the etiological channelopathiological mechanism of DS and action mechanism of CBD on the channels are unclear. In this review, we summarize evidence of the direct and indirect action mechanism of sodium, potassium, calcium, and HCN channels in DS, especially sodium subunits. Some channels' loss-of-function or gain-of-function in inhibitory or excitatory neurons determine the balance of excitatory and inhibitory are associated with DS. A great variety of mechanisms of CBD anticonvulsant effects are focused on modulating these channels, especially sodium, calcium, and potassium channels, which will shed light on ionic channelopathy of DS and the precise molecular treatment of DS in the future.
Collapse
Affiliation(s)
- Changqing Xu
- Department of Child Health and the Child Health Research Institute, School of Medicine, University of Missouri, Columbia, MO, USA
| | - Yumin Zhang
- Department of Anatomy, Physiology and Genetics; Department of Neuroscience, Uniformed Services University School of Medicine, Bethesda, MD, USA
| | - David Gozal
- Department of Child Health and the Child Health Research Institute, School of Medicine, University of Missouri, Columbia, MO, USA
| | - Paul Carney
- Departments of Child Health and Neurology, School of Medicine, University of Missouri, Columbia, MO, USA
| |
Collapse
|
13
|
Auffenberg E, Hedrich UB, Barbieri R, Miely D, Groschup B, Wuttke TV, Vogel N, Lührs P, Zanardi I, Bertelli S, Spielmann N, Gailus-Durner V, Fuchs H, Hrabě de Angelis M, Pusch M, Dichgans M, Lerche H, Gavazzo P, Plesnila N, Freilinger T. Hyperexcitable interneurons trigger cortical spreading depression in an Scn1a migraine model. J Clin Invest 2021; 131:142202. [PMID: 34546973 PMCID: PMC8553559 DOI: 10.1172/jci142202] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 09/02/2021] [Indexed: 12/12/2022] Open
Abstract
Cortical spreading depression (CSD), a wave of depolarization followed by depression of cortical activity, is a pathophysiological process implicated in migraine with aura and various other brain pathologies, such as ischemic stroke and traumatic brain injury. To gain insight into the pathophysiology of CSD, we generated a mouse model for a severe monogenic subtype of migraine with aura, familial hemiplegic migraine type 3 (FHM3). FHM3 is caused by mutations in SCN1A, encoding the voltage-gated Na+ channel NaV1.1 predominantly expressed in inhibitory interneurons. Homozygous Scn1aL1649Q knock-in mice died prematurely, whereas heterozygous mice had a normal lifespan. Heterozygous Scn1aL1649Q knock-in mice compared with WT mice displayed a significantly enhanced susceptibility to CSD. We found L1649Q to cause a gain-of-function effect with an impaired Na+-channel inactivation and increased ramp Na+ currents leading to hyperactivity of fast-spiking inhibitory interneurons. Brain slice recordings using K+-sensitive electrodes revealed an increase in extracellular K+ in the early phase of CSD in heterozygous mice, likely representing the mechanistic link between interneuron hyperactivity and CSD initiation. The neuronal phenotype and premature death of homozygous Scn1aL1649Q knock-in mice was partially rescued by GS967, a blocker of persistent Na+ currents. Collectively, our findings identify interneuron hyperactivity as a mechanism to trigger CSD.
Collapse
Affiliation(s)
- Eva Auffenberg
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.,Institute for Stroke and Dementia Research (ISD), University Hospital, LMU Munich, Munich, Germany
| | - Ulrike Bs Hedrich
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Raffaella Barbieri
- Biophysics Institute, Consiglio Nazionale delle Ricerche (CNR), Genoa, Italy
| | - Daniela Miely
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Bernhard Groschup
- Institute for Stroke and Dementia Research (ISD), University Hospital, LMU Munich, Munich, Germany
| | - Thomas V Wuttke
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.,Department of Neurosurgery, University of Tübingen, Tübingen, Germany
| | - Niklas Vogel
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Philipp Lührs
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Ilaria Zanardi
- Biophysics Institute, Consiglio Nazionale delle Ricerche (CNR), Genoa, Italy
| | - Sara Bertelli
- Biophysics Institute, Consiglio Nazionale delle Ricerche (CNR), Genoa, Italy
| | - Nadine Spielmann
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Valerie Gailus-Durner
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Helmut Fuchs
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Martin Hrabě de Angelis
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany.,Chair of Experimental Genetics, School of Life Science Weihenstephan, Technische Universität München, Freising, Germany.,German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Michael Pusch
- Biophysics Institute, Consiglio Nazionale delle Ricerche (CNR), Genoa, Italy
| | - Martin Dichgans
- Institute for Stroke and Dementia Research (ISD), University Hospital, LMU Munich, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Holger Lerche
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Paola Gavazzo
- Biophysics Institute, Consiglio Nazionale delle Ricerche (CNR), Genoa, Italy
| | - Nikolaus Plesnila
- Institute for Stroke and Dementia Research (ISD), University Hospital, LMU Munich, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Tobias Freilinger
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.,Department of Neurology, Klinikum Passau, Passau, Germany
| |
Collapse
|
14
|
Pernici CD, Mensah JA, Dahle EJ, Johnson KJ, Handy L, Buxton L, Smith MD, West PJ, Metcalf CS, Wilcox KS. Development of an antiseizure drug screening platform for Dravet syndrome at the NINDS contract site for the Epilepsy Therapy Screening Program. Epilepsia 2021; 62:1665-1676. [PMID: 34002394 PMCID: PMC8360068 DOI: 10.1111/epi.16925] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 04/25/2021] [Accepted: 04/27/2021] [Indexed: 02/06/2023]
Abstract
OBJECTIVE Dravet syndrome (DS) is a rare but catastrophic genetic epilepsy, with 80% of patients carrying a mutation in the SCN1A gene. Currently, no antiseizure drug (ASD) exists that adequately controls seizures. In the clinic, individuals with DS often present first with a febrile seizure and, subsequently, generalized tonic-clonic seizures that can continue throughout life. To facilitate the development of ASDs for DS, the contract site of the National Institute of Neurological Disorders and Stroke (NINDS) Epilepsy Therapy Screening Program (ETSP) has evaluated a mouse model of DS using the conditional knock-in Scn1aA1783V/WT mouse. METHODS Survival rates and temperature thresholds for Scn1aA1783V/WT were determined. Prototype ASDs were administered via intraperitoneal injections at the time-to-peak effect, which was previously determined, prior to the induction of hyperthermia-induced seizures. ASDs were considered effective if they significantly increased the temperature at which Scn1aA1783V/WT mice had seizures. RESULTS Approximately 50% of Scn1aA1783V/WT survive to adulthood and all have hyperthermia-induced seizures. The results suggest that hyperthermia-induced seizures in this model of DS are highly refractory to a battery of ASDs. Exceptions were clobazam, tiagabine, levetiracetam, and the combination of clobazam and valproic acid with add-on stiripentol, which elevated seizure thresholds. SIGNIFICANCE Overall, the data demonstrate that the proposed model for DS is suitable for screening novel compounds for the ability to block hyperthermia-induced seizures and that heterozygous mice can be evaluated repeatedly over the course of several weeks, allowing for higher throughput screening.
Collapse
Affiliation(s)
- Chelsea D. Pernici
- Epilepsy Therapy Screening Program (ETSP) Contract SiteUniversity of UtahSalt Lake CityUTUSA
- Department of Pharmacology and ToxicologyUniversity of UtahSalt Lake CityUTUSA
| | - Jeffrey A. Mensah
- Department of Pharmacology and ToxicologyUniversity of UtahSalt Lake CityUTUSA
| | - E. Jill Dahle
- Epilepsy Therapy Screening Program (ETSP) Contract SiteUniversity of UtahSalt Lake CityUTUSA
- Department of Pharmacology and ToxicologyUniversity of UtahSalt Lake CityUTUSA
| | - Kristina J. Johnson
- Epilepsy Therapy Screening Program (ETSP) Contract SiteUniversity of UtahSalt Lake CityUTUSA
| | - Laura Handy
- Epilepsy Therapy Screening Program (ETSP) Contract SiteUniversity of UtahSalt Lake CityUTUSA
| | - Lauren Buxton
- Epilepsy Therapy Screening Program (ETSP) Contract SiteUniversity of UtahSalt Lake CityUTUSA
- Department of Pharmacology and ToxicologyUniversity of UtahSalt Lake CityUTUSA
| | - Misty D. Smith
- Epilepsy Therapy Screening Program (ETSP) Contract SiteUniversity of UtahSalt Lake CityUTUSA
- Department of Pharmacology and ToxicologyUniversity of UtahSalt Lake CityUTUSA
| | - Peter J. West
- Epilepsy Therapy Screening Program (ETSP) Contract SiteUniversity of UtahSalt Lake CityUTUSA
- Department of Pharmacology and ToxicologyUniversity of UtahSalt Lake CityUTUSA
| | - Cameron S. Metcalf
- Epilepsy Therapy Screening Program (ETSP) Contract SiteUniversity of UtahSalt Lake CityUTUSA
- Department of Pharmacology and ToxicologyUniversity of UtahSalt Lake CityUTUSA
| | - Karen S. Wilcox
- Epilepsy Therapy Screening Program (ETSP) Contract SiteUniversity of UtahSalt Lake CityUTUSA
- Department of Pharmacology and ToxicologyUniversity of UtahSalt Lake CityUTUSA
| |
Collapse
|
15
|
Abstract
Genetic testing has yielded major advances in our understanding of the causes of epilepsy. Seizures remain resistant to treatment in a significant proportion of cases, particularly in severe, childhood-onset epilepsy, the patient population in which an underlying causative genetic variant is most likely to be identified. A genetic diagnosis can be explanatory as to etiology, and, in some cases, might suggest a therapeutic approach; yet, a clear path from genetic diagnosis to treatment remains unclear in most cases. Here, we discuss theoretical considerations behind the attempted use of small molecules for the treatment of genetic epilepsies, which is but one among various approaches currently under development. We explore a few salient examples and consider the future of the small molecule approach for genetic epilepsies. We conclude that significant additional work is required to understand how genetic variation leads to dysfunction of epilepsy-associated protein targets, and how this impacts the function of diverse subtypes of neurons embedded within distributed brain circuits to yield epilepsy and epilepsy-associated comorbidities. A syndrome- or even variant-specific approach may be required to achieve progress. Advances in the field will require improved methods for large-scale target validation, compound identification and optimization, and the development of accurate model systems that reflect the core features of human epilepsy syndromes, as well as novel approaches towards clinical trials of such compounds in small rare disease cohorts.
Collapse
Affiliation(s)
- Ethan M Goldberg
- Department of Pediatrics, Division of Neurology, Abramson Research Center, The Epilepsy Neurogenetics Initiative, The Children's Hospital of Philadelphia, Abramson Research Center Room 502A, 19104, Philadelphia, PA, USA.
- Departments of Neurology and Neuroscience, The University of Pennsylvania Perelman School of Medicine, 19104, Philadelphia, PA, USA.
| |
Collapse
|
16
|
Satpute Janve V, Anderson LL, Bahceci D, Hawkins NA, Kearney JA, Arnold JC. The Heat Sensing Trpv1 Receptor Is Not a Viable Anticonvulsant Drug Target in the Scn1a +/- Mouse Model of Dravet Syndrome. Front Pharmacol 2021; 12:675128. [PMID: 34079465 PMCID: PMC8165383 DOI: 10.3389/fphar.2021.675128] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 04/27/2021] [Indexed: 11/13/2022] Open
Abstract
Cannabidiol has been approved for the treatment of drug-resistant childhood epilepsies including Dravet syndrome (DS). Although the mechanism of anticonvulsant action of cannabidiol is unknown, emerging data suggests involvement of the transient receptor potential cation channel subfamily V member 1 (Trpv1). Pharmacological and genetic studies in conventional seizure models suggest Trpv1 is a novel anticonvulsant target. However, whether targeting Trpv1 is anticonvulsant in animal models of drug-resistant epilepsies is not known. Thus, we examined whether Trpv1 affects the epilepsy phenotype of the F1.Scn1a +/- mouse model of DS. We found that cortical Trpv1 mRNA expression was increased in seizure susceptible F1.Scn1a +/- mice with a hybrid genetic background compared to seizure resistant 129.Scn1a +/- mice isogenic on 129S6/SvEvTac background, suggesting Trpv1 could be a genetic modifier. Previous studies show functional loss of Trpv1 is anticonvulsant. However, Trpv1 selective antagonist SB-705498 did not affect hyperthermia-induced seizure threshold, frequency of spontaneous seizures or survival of F1.Scn1a +/- mice. Surprisingly, Trpv1 deletion had both pro- and anti-seizure effects. Trpv1 deletion did not affect hyperthermia-induced seizure temperature thresholds of F1.Scn1a +/- ; Trpv1 +/- at P14-16 but was proconvulsant at P18 as it reduced seizure temperature thresholds. Conversely, Trpv1 deletion did not alter the frequency of spontaneous seizures but reduced their severity. These results suggest that Trpv1 is a modest genetic modifier of spontaneous seizure severity in the F1.Scn1a +/- model of DS. However, the opposing pro- and anti-seizure effects of Trpv1 deletion and the lack of effects of Trpv1 inhibition suggest that Trpv1 is unlikely a viable anticonvulsant drug target in DS.
Collapse
Affiliation(s)
- Vaishali Satpute Janve
- Lambert Initiative for Cannabinoid Therapeutics, Brain and Mind Centre, Sydney, NSW, Australia.,Discipline of Pharmacology, Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Lyndsey L Anderson
- Lambert Initiative for Cannabinoid Therapeutics, Brain and Mind Centre, Sydney, NSW, Australia.,Discipline of Pharmacology, Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Dilara Bahceci
- Lambert Initiative for Cannabinoid Therapeutics, Brain and Mind Centre, Sydney, NSW, Australia.,Discipline of Pharmacology, Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Nicole A Hawkins
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Jennifer A Kearney
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Jonathon C Arnold
- Lambert Initiative for Cannabinoid Therapeutics, Brain and Mind Centre, Sydney, NSW, Australia.,Discipline of Pharmacology, Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| |
Collapse
|
17
|
Hézső T, Naveed M, Dienes C, Kiss D, Prorok J, Árpádffy-Lovas T, Varga R, Fujii E, Mercan T, Topal L, Kistamás K, Szentandrássy N, Almássy J, Jost N, Magyar J, Bányász T, Baczkó I, Varró A, Nánási PP, Virág L, Horváth B. Mexiletine-like cellular electrophysiological effects of GS967 in canine ventricular myocardium. Sci Rep 2021; 11:9565. [PMID: 33953276 PMCID: PMC8100105 DOI: 10.1038/s41598-021-88903-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 03/26/2021] [Indexed: 12/14/2022] Open
Abstract
Enhancement of the late Na+ current (INaL) increases arrhythmia propensity in the heart, while suppression of the current is antiarrhythmic. GS967 is an agent considered as a selective blocker of INaL. In the present study, effects of GS967 on INaL and action potential (AP) morphology were studied in canine ventricular myocytes by using conventional voltage clamp, action potential voltage clamp and sharp microelectrode techniques. The effects of GS967 (1 µM) were compared to those of the class I/B antiarrhythmic compound mexiletine (40 µM). Under conventional voltage clamp conditions, INaL was significantly suppressed by GS967 and mexiletine, causing 80.4 ± 2.2% and 59.1 ± 1.8% reduction of the densities of INaL measured at 50 ms of depolarization, and 79.0 ± 3.1% and 63.3 ± 2.7% reduction of the corresponding current integrals, respectively. Both drugs shifted the voltage dependence of the steady-state inactivation curve of INaL towards negative potentials. GS967 and mexiletine dissected inward INaL profiles under AP voltage clamp conditions having densities, measured at 50% of AP duration (APD), of −0.37 ± 0.07 and −0.28 ± 0.03 A/F, and current integrals of −56.7 ± 9.1 and −46.6 ± 5.5 mC/F, respectively. Drug effects on peak Na+ current (INaP) were assessed by recording the maximum velocity of AP upstroke (V+max) in multicellular preparations. The offset time constant was threefold faster for GS967 than mexiletine (110 ms versus 289 ms), while the onset of the rate-dependent block was slower in the case of GS967. Effects on beat-to-beat variability of APD was studied in isolated myocytes. Beat-to-beat variability was significantly decreased by both GS967 and mexiletine (reduction of 42.1 ± 6.5% and 24.6 ± 12.8%, respectively) while their shortening effect on APD was comparable. It is concluded that the electrophysiological effects of GS967 are similar to those of mexiletine, but with somewhat faster offset kinetics of V+max block. However, since GS967 depressed V+max and INaL at the same concentration, the current view that GS967 represents a new class of drugs that selectively block INaL has to be questioned and it is suggested that GS967 should be classified as a class I/B antiarrhythmic agent.
Collapse
Affiliation(s)
- Tamás Hézső
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, 4012, Debrecen, Hungary
| | - Muhammad Naveed
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Dóm tér 12, 6701, Szeged, Hungary
| | - Csaba Dienes
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, 4012, Debrecen, Hungary
| | - Dénes Kiss
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, 4012, Debrecen, Hungary
| | - János Prorok
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Dóm tér 12, 6701, Szeged, Hungary.,MTA-SZTE Research Group for Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - Tamás Árpádffy-Lovas
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Dóm tér 12, 6701, Szeged, Hungary
| | - Richárd Varga
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Dóm tér 12, 6701, Szeged, Hungary
| | - Erika Fujii
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, 4012, Debrecen, Hungary
| | - Tanju Mercan
- Department of Biophysics, School of Medicine, Akdeniz University, Antalya, Turkey
| | - Leila Topal
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Dóm tér 12, 6701, Szeged, Hungary
| | - Kornél Kistamás
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, 4012, Debrecen, Hungary
| | - Norbert Szentandrássy
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, 4012, Debrecen, Hungary.,Department of Basic Medical Sciences, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - János Almássy
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, 4012, Debrecen, Hungary
| | - Norbert Jost
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Dóm tér 12, 6701, Szeged, Hungary.,MTA-SZTE Research Group for Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - János Magyar
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, 4012, Debrecen, Hungary.,Division of Sport Physiology, Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Tamás Bányász
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, 4012, Debrecen, Hungary
| | - István Baczkó
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Dóm tér 12, 6701, Szeged, Hungary.,Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Szeged, Hungary
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Dóm tér 12, 6701, Szeged, Hungary. .,MTA-SZTE Research Group for Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary. .,Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Szeged, Hungary.
| | - Péter P Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, 4012, Debrecen, Hungary. .,Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary.
| | - László Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Dóm tér 12, 6701, Szeged, Hungary.,Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Szeged, Hungary
| | - Balázs Horváth
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, 4012, Debrecen, Hungary.,Faculty of Pharmacy, University of Debrecen, Debrecen, Hungary
| |
Collapse
|
18
|
Mantegazza M, Cestèle S, Catterall WA. Sodium channelopathies of skeletal muscle and brain. Physiol Rev 2021; 101:1633-1689. [PMID: 33769100 DOI: 10.1152/physrev.00025.2020] [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] [Indexed: 12/15/2022] Open
Abstract
Voltage-gated sodium channels initiate action potentials in nerve, skeletal muscle, and other electrically excitable cells. Mutations in them cause a wide range of diseases. These channelopathy mutations affect every aspect of sodium channel function, including voltage sensing, voltage-dependent activation, ion conductance, fast and slow inactivation, and both biosynthesis and assembly. Mutations that cause different forms of periodic paralysis in skeletal muscle were discovered first and have provided a template for understanding structure, function, and pathophysiology at the molecular level. More recent work has revealed multiple sodium channelopathies in the brain. Here we review the well-characterized genetics and pathophysiology of the periodic paralyses of skeletal muscle and then use this information as a foundation for advancing our understanding of mutations in the structurally homologous α-subunits of brain sodium channels that cause epilepsy, migraine, autism, and related comorbidities. We include studies based on molecular and structural biology, cell biology and physiology, pharmacology, and mouse genetics. Our review reveals unexpected connections among these different types of sodium channelopathies.
Collapse
Affiliation(s)
- Massimo Mantegazza
- Université Cote d'Azur, Valbonne-Sophia Antipolis, France.,CNRS UMR7275, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne-Sophia Antipolis, France.,INSERM, Valbonne-Sophia Antipolis, France
| | - Sandrine Cestèle
- Université Cote d'Azur, Valbonne-Sophia Antipolis, France.,CNRS UMR7275, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne-Sophia Antipolis, France
| | | |
Collapse
|
19
|
Abstract
The voltage-gated sodium channel α-subunit genes comprise a highly conserved gene family. Mutations of three of these genes, SCN1A, SCN2A and SCN8A, are responsible for a significant burden of neurological disease. Recent progress in identification and functional characterization of patient variants is generating new insights and novel approaches to therapy for these devastating disorders. Here we review the basic elements of sodium channel function that are used to characterize patient variants. We summarize a large body of work using global and conditional mouse mutants to characterize the in vivo roles of these channels. We provide an overview of the neurological disorders associated with mutations of the human genes and examples of the effects of patient mutations on channel function. Finally, we highlight therapeutic interventions that are emerging from new insights into mechanisms of sodium channelopathies.
Collapse
|
20
|
Anderson LL, Ametovski A, Lin Luo J, Everett-Morgan D, McGregor IS, Banister SD, Arnold JC. Cannabichromene, Related Phytocannabinoids, and 5-Fluoro-cannabichromene Have Anticonvulsant Properties in a Mouse Model of Dravet Syndrome. ACS Chem Neurosci 2021; 12:330-339. [PMID: 33395525 DOI: 10.1021/acschemneuro.0c00677] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Cannabis-based products are increasingly being used to treat refractory childhood epilepsies such as Dravet syndrome. Cannabis contains at least 140 terpenophenolic compounds known as phytocannabinoids. These include the known anticonvulsant compound cannabidiol (CBD) and several molecules showing emergent anticonvulsant properties in animal models. Cannabichromene (CBC) is a phytocannabinoid frequently detected in artisanal cannabis oils used in the community by childhood epilepsy patients. Here we examined the brain and plasma pharmacokinetic profiles of CBC, cannabichromenic acid (CBCA), cannabichromevarin (CBCV), and cannabichromevarinic acid (CBCVA) following intraperitoneal administration in mice. The anticonvulsant potential of each was then tested against hyperthermia-induced seizures in the Scn1a+/- mouse model of Dravet syndrome. All phytocannabinoids within the CBC series were readily absorbed and showed substantial brain penetration (brain-plasma ratios ranging from 0.2 to 5.8). Anticonvulsant efficacy was evident with CBC, CBCA, and CBCVA, each significantly increasing the temperature threshold at which Scn1a+/- mice had a generalized tonic-clonic seizure. We synthesized a fluorinated derivative of CBC (5-fluoro-CBC), which showed improved brain penetration relative to the parent CBC molecule but not any greater anticonvulsant effect. Since CBC and derivatives are anticonvulsant in a model of intractable pediatric epilepsy, they may constitute part of the mechanism through which artisanal cannabis oils are anticonvulsant in patients.
Collapse
Affiliation(s)
- Lyndsey L. Anderson
- Brain and Mind Centre, The University of Sydney, Sydney, NSW 2050, Australia
- Discipline of Pharmacology, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia
- Lambert Initiative for Cannabinoid Therapeutics, The University of Sydney, Sydney, NSW 2050, Australia
| | - Adam Ametovski
- Brain and Mind Centre, The University of Sydney, Sydney, NSW 2050, Australia
- Lambert Initiative for Cannabinoid Therapeutics, The University of Sydney, Sydney, NSW 2050, Australia
- School of Chemistry, Faculty of Science, The University of Sydney, Sydney, NSW 2050, Australia
| | - Jia Lin Luo
- Brain and Mind Centre, The University of Sydney, Sydney, NSW 2050, Australia
- Lambert Initiative for Cannabinoid Therapeutics, The University of Sydney, Sydney, NSW 2050, Australia
- School of Psychology, Faculty of Science, The University of Sydney, Sydney, NSW 2050, Australia
| | - Declan Everett-Morgan
- Lambert Initiative for Cannabinoid Therapeutics, The University of Sydney, Sydney, NSW 2050, Australia
| | - Iain S. McGregor
- Brain and Mind Centre, The University of Sydney, Sydney, NSW 2050, Australia
- Discipline of Pharmacology, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia
- School of Psychology, Faculty of Science, The University of Sydney, Sydney, NSW 2050, Australia
| | - Samuel D. Banister
- Brain and Mind Centre, The University of Sydney, Sydney, NSW 2050, Australia
- Lambert Initiative for Cannabinoid Therapeutics, The University of Sydney, Sydney, NSW 2050, Australia
- School of Chemistry, Faculty of Science, The University of Sydney, Sydney, NSW 2050, Australia
| | - Jonathon C. Arnold
- Brain and Mind Centre, The University of Sydney, Sydney, NSW 2050, Australia
- Discipline of Pharmacology, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia
- Lambert Initiative for Cannabinoid Therapeutics, The University of Sydney, Sydney, NSW 2050, Australia
| |
Collapse
|
21
|
Jones LB, Peters CH, Rosch RE, Owers M, Hughes E, Pal DK, Ruben PC. The L1624Q Variant in SCN1A Causes Familial Epilepsy Through a Mixed Gain and Loss of Channel Function. Front Pharmacol 2021; 12:788192. [PMID: 34925043 PMCID: PMC8675213 DOI: 10.3389/fphar.2021.788192] [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: 10/01/2021] [Accepted: 11/17/2021] [Indexed: 11/13/2022] Open
Abstract
Variants of the SCN1A gene encoding the neuronal voltage-gated sodium channel NaV1.1 cause over 85% of all cases of Dravet syndrome, a severe and often pharmacoresistent epileptic encephalopathy with mostly infantile onset. But with the increased availability of genetic testing for patients with epilepsy, variants in SCN1A have now also been described in a range of other epilepsy phenotypes. The vast majority of these epilepsy-associated variants are de novo, and most are either nonsense variants that truncate the channel or missense variants that are presumed to cause loss of channel function. However, biophysical analysis has revealed a significant subset of missense mutations that result in increased excitability, further complicating approaches to precision pharmacotherapy for patients with SCN1A variants and epilepsy. We describe clinical and biophysical data of a familial SCN1A variant encoding the NaV1.1 L1624Q mutant. This substitution is located on the extracellular linker between S3 and S4 of Domain IV of NaV1.1 and is a rare case of a familial SCN1A variant causing an autosomal dominant frontal lobe epilepsy. We expressed wild-type (WT) and L1642Q channels in CHO cells. Using patch-clamp to characterize channel properties at several temperatures, we show that the L1624Q variant increases persistent current, accelerates fast inactivation onset and decreases current density. While SCN1A-associated epilepsy is typically considered a loss-of-function disease, our results put L1624Q into a growing set of mixed gain and loss-of-function variants in SCN1A responsible for epilepsy.
Collapse
Affiliation(s)
- Laura B Jones
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Colin H Peters
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Richard E Rosch
- MRC Centre for Neurodevelopmental Disorders, King's College London, London, United Kingdom.,Department of Paediatric Neurology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Maxine Owers
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Elaine Hughes
- Department of Paediatric Neurosciences, King's College Hospital, London, United Kingdom.,Department of Paediatric Neurosciences, Evelina London Children's Hospital, London, United Kingdom
| | - Deb K Pal
- MRC Centre for Neurodevelopmental Disorders, King's College London, London, United Kingdom.,Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology, and Neuroscience, King's College London, London, United Kingdom
| | - Peter C Ruben
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| |
Collapse
|
22
|
Abstract
Voltage-gated sodium channels (VGSCs) are foundational to excitable cell function: Their coordinated passage of sodium ions into the cell is critical for the generation and propagation of action potentials throughout the nervous system. The classical paradigm of action potential physiology states that sodium passes through the membrane only transiently (1-2 milliseconds), before the channels inactivate and cease to conduct sodium ions. However, in reality, a small fraction of the total sodium current (1%-2%) remains at steady state despite prolonged depolarization. While this persistent sodium current (INaP) contributes to normal physiological functioning of neurons, accumulating evidence indicates a particularly pathogenic role for an elevated INaP in epilepsy (reviewed previously1). Due to significant advances over the past decade of epilepsy research concerning the importance of INaP in sodium channelopathies, this review seeks to summarize recent evidence and highlight promising novel anti-seizure medication strategies through preferentially targeting INaP.
Collapse
Affiliation(s)
- Eric R. Wengert
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, USA
- Neuroscience Graduate Program, University of Virginia, Charlottesville, VA, USA
| | - Manoj K. Patel
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, USA
- Neuroscience Graduate Program, University of Virginia, Charlottesville, VA, USA
| |
Collapse
|
23
|
Miziak B, Czuczwar S. Advances in the design and discovery of novel small molecule drugs for the treatment of Dravet Syndrome. Expert Opin Drug Discov 2020; 16:579-593. [PMID: 33275464 DOI: 10.1080/17460441.2021.1857722] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Introduction: Dravet syndrome (severe myoclonic epilepsy in infancy) begins in the first year of life characterized by generalized or unilateral clonic seizures that are frequently triggered by high fever. A subsequent worsening stage occurs (in years 1-4 of life) and seizure activity is accompanied by disturbed psychomotor development. The third stage of the disease, known as the 'stabilization phase,' is associated with seizures and intellectual impairment. Of note, a mutation in the voltage-gated sodium-channel gene α 1 subunit (SCN1A) has been found in around 85% of patients with Dravet syndrome.Areas covered: The authors review the current treatment strategies as well as potential drugs in the initial stages of clinical evaluation. The authors also review drugs with protective activity in mice models of Dravet syndrome.Expert opinion: Experimental data and results from initial clinical studies have brought attention to several drugs with various mechanisms of action including: ataluren (a suppressant of premature stop codons; under clinical evaluation), EPX-100, EPX-200, fenfluramine (serotonin modulators), soticlestat (an 24-hydroxylase cholesterol enzyme inhibitor), SPN-817 (an inhibitor of acetylcholinesterase), verapamil (a voltage-dependent calcium channel inhibitor) and STK-001 (an antisense oligonucleotide). The latter is scheduled for clinical evaluation.
Collapse
Affiliation(s)
- Barbara Miziak
- Department of Pathophysiology, Medical University of Lublin, Lublin, Poland
| | - Stanisław Czuczwar
- Department of Pathophysiology, Medical University of Lublin, Lublin, Poland
| |
Collapse
|
24
|
Anderson LL, Low IK, McGregor IS, Arnold JC. Interactions between cannabidiol and Δ 9 -tetrahydrocannabinol in modulating seizure susceptibility and survival in a mouse model of Dravet syndrome. Br J Pharmacol 2020; 177:4261-4274. [PMID: 32608111 DOI: 10.1111/bph.15181] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 05/28/2020] [Accepted: 06/24/2020] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND AND PURPOSE Extracts from the cannabis plant can dramatically improve the health of children suffering from refractory epilepsies such as Dravet syndrome. These extracts typically contain cannabidiol (CBD), a phytocannabinoid with well-documented anticonvulsant effects, but may also contain Δ9 -tetrahydrocannabinol (Δ9 -THC). It is unclear whether the presence of Δ9 -THC modulates the anticonvulsant efficacy of CBD. Here, we utilized the Scn1a+/- mouse model of Dravet syndrome to examine this question. EXPERIMENTAL APPROACH Scn1a+/- mice recapitulate core features of Dravet syndrome, including hyperthermia-induced seizures, early onset spontaneous seizures and sudden death. We assessed the effects on CBD and Δ9 -THC alone, and in combination on hyperthermia-induced seizures, spontaneous seizures and premature mortality. KEY RESULTS Administered alone, CBD (100 mg·kg-1 i.p.) was anticonvulsant against hyperthermia-induced seizures as were low (0.1 and 0.3 mg·kg-1 i.p.) but not higher doses of Δ9 -THC. A subthreshold dose of CBD (12 mg·kg-1 ) enhanced the anticonvulsant effects of Δ9 -THC (0.1 mg·kg-1 ). Sub-chronic oral administration of Δ9 -THC or CBD alone did not affect spontaneous seizure frequency or mortality while, surprisingly, their co-administration increased the severity of spontaneous seizures and overall mortality. CONCLUSION AND IMPLICATIONS Low doses of Δ9 -THC are anticonvulsant against hyperthermia-induced seizures in Scn1a+/- mice, effects that are enhanced by a sub-anticonvulsant dose of CBD. However, proconvulsant effects and increased premature mortality are observed when CBD and Δ9 -THC are sub-chronically dosed in combination. The possible explanations and implications of this are discussed.
Collapse
Affiliation(s)
- Lyndsey L Anderson
- Brain and Mind Centre, The University of Sydney, Sydney, New South Wales, Australia.,Discipline of Pharmacology, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.,Lambert Initiative for Cannabinoid Therapeutics, The University of Sydney, Sydney, New South Wales, Australia
| | - Ivan K Low
- Lambert Initiative for Cannabinoid Therapeutics, The University of Sydney, Sydney, New South Wales, Australia
| | - Iain S McGregor
- Brain and Mind Centre, The University of Sydney, Sydney, New South Wales, Australia.,Lambert Initiative for Cannabinoid Therapeutics, The University of Sydney, Sydney, New South Wales, Australia.,School of Psychology, Faculty of Science, The University of Sydney, Sydney, New South Wales, Australia
| | - Jonathon C Arnold
- Brain and Mind Centre, The University of Sydney, Sydney, New South Wales, Australia.,Discipline of Pharmacology, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.,Lambert Initiative for Cannabinoid Therapeutics, The University of Sydney, Sydney, New South Wales, Australia
| |
Collapse
|
25
|
Brunklaus A, Lal D. Sodium channel epilepsies and neurodevelopmental disorders: from disease mechanisms to clinical application. Dev Med Child Neurol 2020; 62:784-792. [PMID: 32227486 DOI: 10.1111/dmcn.14519] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/04/2020] [Indexed: 12/18/2022]
Abstract
Genetic variants in brain-expressed voltage-gated sodium channels (SCNs) have emerged as one of the most frequent causes of Mendelian forms of epilepsy and neurodevelopmental disorders (NDDs). This review explores the biological concepts that underlie sodium channel NDDs, explains their phenotypic heterogeneity, and appraises how this knowledge may inform clinical practice. We observe that excitatory/inhibitory neuronal expression ratios of sodium channels are important regulatory mechanisms underlying brain development, homeostasis, and neurological diseases. We hypothesize that a detailed understanding of gene expression, variant tolerance, location, and function, as well as timing of seizure onset can aid the understanding of how variants in SCN1A, SCN2A, SCN3A, and SCN8A contribute to seizure aetiology and inform treatment choice. We propose a model in which variant type, development-specific gene expression, and functions of SCNs explain the heterogeneity of sodium channel associated NDDs. Understanding of basic disease mechanisms and detailed knowledge of variant characteristics have increasing influence on clinical decision making, enabling us to stratify treatment and move closer towards precision medicine in sodium channel epilepsy and NDDs. WHAT THIS PAPER ADDS: Sodium-channel disorder heterogeneity is explained by variant-specific gene expression timing and function. Gene tolerance and location analyses aid sodium channel variant interpretation. Sodium-channel variant characteristics can contribute to clinical decision making.
Collapse
Affiliation(s)
- Andreas Brunklaus
- The Paediatric Neurosciences Research Group, Royal Hospital for Children, Glasgow, UK.,School of Medicine, University of Glasgow, Glasgow, UK
| | - Dennis Lal
- Cologne Center for Genomics, University Hospital Cologne, University of Cologne, Cologne, Germany.,Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA.,Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, MA, USA.,Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH, USA.,Genomic Medicine Institute, Lerner Research Institute Cleveland Clinic, Cleveland, OH, USA
| |
Collapse
|
26
|
Electrophysiological Alterations of Pyramidal Cells and Interneurons of the CA1 Region of the Hippocampus in a Novel Mouse Model of Dravet Syndrome. Genetics 2020; 215:1055-1066. [PMID: 32554600 DOI: 10.1534/genetics.120.303399] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 06/05/2020] [Indexed: 11/18/2022] Open
Abstract
Dravet syndrome is a developmental epileptic encephalopathy caused by pathogenic variation in SCN1A To characterize the pathogenic substitution (p.H939R) of a local individual with Dravet syndrome, fibroblast cells from the individual were reprogrammed to pluripotent stem cells and differentiated into neurons. Sodium currents of these neurons were compared with healthy control induced neurons. A novel Scn1a H939R/+ mouse model was generated with the p.H939R substitution. Immunohistochemistry and electrophysiological experiments were performed on hippocampal slices of Scn1a H939R/+ mice. We found that the sodium currents recorded in the proband-induced neurons were significantly smaller and slower compared to wild type (WT). The resting membrane potential and spike amplitude were significantly depolarized in the proband-induced neurons. Similar differences in resting membrane potential and spike amplitude were observed in the interneurons of the hippocampus of Scn1a H939R/+ mice. The Scn1a H939R/+ mice showed the characteristic features of a Dravet-like phenotype: increased mortality and both spontaneous and heat-induced seizures. Immunohistochemistry showed a reduction in amount of parvalbumin and vesicular acetylcholine transporter in the hippocampus of Scn1a H939R/+ compared to WT mice. Overall, these results underline hyper-excitability of the hippocampal CA1 circuit of this novel mouse model of Dravet syndrome which, under certain conditions, such as temperature, can trigger seizure activity. This hyper-excitability is due to the altered electrophysiological properties of pyramidal neurons and interneurons which are caused by the dysfunction of the sodium channel bearing the p.H939R substitution. This novel Dravet syndrome model also highlights the reduction in acetylcholine and the contribution of pyramidal cells, in addition to interneurons, to network hyper-excitability.
Collapse
|
27
|
D'Adamo MC, Liantonio A, Conte E, Pessia M, Imbrici P. Ion Channels Involvement in Neurodevelopmental Disorders. Neuroscience 2020; 440:337-359. [PMID: 32473276 DOI: 10.1016/j.neuroscience.2020.05.032] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 05/16/2020] [Accepted: 05/19/2020] [Indexed: 12/14/2022]
Abstract
Inherited and sporadic mutations in genes encoding for brain ion channels, affecting membrane expression or biophysical properties, have been associated with neurodevelopmental disorders characterized by epilepsy, cognitive and behavioral deficits with significant phenotypic and genetic heterogeneity. Over the years, the screening of a growing number of patients and the functional characterization of newly identified mutations in ion channels genes allowed to recognize new phenotypes and to widen the clinical spectrum of known diseases. Furthermore, advancements in understanding disease pathogenesis at atomic level or using patient-derived iPSCs and animal models have been pivotal to orient therapeutic intervention and to put the basis for the development of novel pharmacological options for drug-resistant disorders. In this review we will discuss major improvements and critical issues concerning neurodevelopmental disorders caused by dysfunctions in brain sodium, potassium, calcium, chloride and ligand-gated ion channels.
Collapse
Affiliation(s)
- Maria Cristina D'Adamo
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Malta
| | | | - Elena Conte
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Italy
| | - Mauro Pessia
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Malta; Department of Physiology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Paola Imbrici
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Italy.
| |
Collapse
|
28
|
Meisler MH. SCN8A encephalopathy: Mechanisms and models. Epilepsia 2020; 60 Suppl 3:S86-S91. [PMID: 31904118 DOI: 10.1111/epi.14703] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 03/06/2019] [Accepted: 03/06/2019] [Indexed: 12/12/2022]
Abstract
De novo mutations of the neuronal sodium channel SCN8A have been identified in approximately 2% of individuals with epileptic encephalopathy. These missense mutations alter the biophysical properties of sodium channel Nav1.6 in ways that lead to neuronal hyperexcitability. We generated two mouse models carrying patient mutations N1768D and R1872W to examine the effects on neuronal function in vivo. The conditional R1872W mutation is activated by expression of CRE recombinase, permitting characterization of the effects of the mutation on different classes of neurons and at different points in postnatal development. Preclinical drug testing in these mouse models provides support for several new therapies for this devastating disorder. In contrast with the gain-of-function mutations in epilepsy, mutations of SCN8A that result in partial or complete loss of function are associated with intellectual disability and other disorders.
Collapse
Affiliation(s)
- Miriam H Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan
| |
Collapse
|
29
|
Patra PH, Serafeimidou-Pouliou E, Bazelot M, Whalley BJ, Williams CM, McNeish AJ. Cannabidiol improves survival and behavioural co-morbidities of Dravet syndrome in mice. Br J Pharmacol 2020; 177:2779-2792. [PMID: 32321192 PMCID: PMC7236080 DOI: 10.1111/bph.15003] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 12/16/2019] [Accepted: 01/07/2020] [Indexed: 12/21/2022] Open
Abstract
Background and Purpose Dravet syndrome is a severe, genetic form of paediatric epilepsy associated with premature mortality and co‐morbidities such as anxiety, depression, autism, motor dysfunction and memory deficits. Cannabidiol is an approved anticonvulsive drug in the United States and Europe for seizures associated with Dravet syndrome in patients 2 years of age and older. We investigated its potential to prevent premature mortality and improve associated co‐morbidities. Experimental Approach The efficacy of sub‐chronic cannabidiol administration in two mouse models of Dravet syndrome was investigated. The effect of cannabidiol on neonatal welfare and survival was studied using Scn1a−/− mice. We then used a hybrid, heterozygote Scn1a+/− mouse model to study the effect of cannabidiol on survival and behavioural co‐morbidities: motor deficits (rotarod and static‐beam test), gait abnormality (gait test), social anxiety (social interaction test), anxiety‐like (elevated plus maze) and depressive‐like behaviours (sucrose preference test) and cognitive impairment (radial arm maze test). Key Results In Scn1a−/− mice, cannabidiol increased survival and delayed worsening of neonatal welfare. In Scn1a+/− mice, chronic cannabidiol administration did not show any adverse effect on motor function and gait, reduced premature mortality, improved social behaviour and memory function, and reduced anxiety‐like and depressive‐like behaviours. Conclusion and Implications We are the first to demonstrate a potential disease‐modifying effect of cannabidiol in animal models of Dravet syndrome. Cannabidiol treatment reduced premature mortality and improved several behavioural co‐morbidities in Dravet syndrome mice. These crucial findings may be translated into human therapy to address behavioural co‐morbidities associated with Dravet syndrome.
Collapse
Affiliation(s)
- Pabitra Hriday Patra
- School of Pharmacy, University of Reading, Reading, UK.,School of Psychology and Clinical Language Sciences, University of Reading, Reading, UK
| | | | | | | | | | | |
Collapse
|
30
|
Mason ER, Cummins TR. Differential Inhibition of Human Nav1.2 Resurgent and Persistent Sodium Currents by Cannabidiol and GS967. Int J Mol Sci 2020; 21:ijms21072454. [PMID: 32244818 PMCID: PMC7177867 DOI: 10.3390/ijms21072454] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 03/27/2020] [Accepted: 03/28/2020] [Indexed: 12/24/2022] Open
Abstract
Many epilepsy patients are refractory to conventional antiepileptic drugs. Resurgent and persistent currents can be enhanced by epilepsy mutations in the Nav1.2 channel, but conventional antiepileptic drugs inhibit normal transient currents through these channels, along with aberrant resurgent and persistent currents that are enhanced by Nav1.2 epilepsy mutations. Pharmacotherapies that specifically target aberrant resurgent and/or persistent currents would likely have fewer unwanted side effects and be effective in many patients with refractory epilepsy. This study investigated the effects of cannbidiol (CBD) and GS967 (each at 1 μM) on transient, resurgent, and persistent currents in human embryonic kidney (HEK) cells stably expressing wild-type hNav1.2 channels. We found that CBD preferentially inhibits resurgent currents over transient currents in this paradigm; and that GS967 preferentially inhibits persistent currents over transient currents. Therefore, CBD and GS967 may represent a new class of more targeted and effective antiepileptic drugs.
Collapse
Affiliation(s)
- Emily R. Mason
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, IUPUI campus, Indianapolis, IN 46202, USA
- Correspondence:
| | - Theodore R. Cummins
- Department of Biology, Purdue School of Science, IUPUI campus, Indianapolis, IN 46202, USA;
| |
Collapse
|
31
|
Du J, Simmons S, Brunklaus A, Adiconis X, Hession CC, Fu Z, Li Y, Shema R, Møller RS, Barak B, Feng G, Meisler M, Sanders S, Lerche H, Campbell AJ, McCarroll S, Levin JZ, Lal D. Differential excitatory vs inhibitory SCN expression at single cell level regulates brain sodium channel function in neurodevelopmental disorders. Eur J Paediatr Neurol 2020; 24:129-133. [PMID: 31928904 DOI: 10.1016/j.ejpn.2019.12.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 12/18/2019] [Indexed: 10/25/2022]
Abstract
The four voltage-gated sodium channels SCN1/2/3/8A have been associated with heterogeneous types of developmental disorders, each presenting with disease specific temporal and cell type specific gene expression. Using single-cell RNA sequencing transcriptomic data from humans and mice, we observe that SCN1A is predominantly expressed in inhibitory neurons. In contrast, SCN2/3/8A are profoundly expressed in excitatory neurons with SCN2/3A starting prenatally, followed by SCN1/8A neonatally. In contrast to previous observations from low resolution RNA screens, we observe that all four genes are expressed in both excitatory and inhibitory neurons, however, exhibit differential expression strength. These findings provide molecular evidence, at single-cell resolution, to support the hypothesis that the excitatory/inhibitory (E/I) neuronal expression ratios of sodium channels are important regulatory mechanisms underlying brain homeostasis and neurological diseases. Modulating the E/I expression balance within cell types of sodium channels could serve as a potential strategy to develop targeted treatment for NaV-associated neuronal developmental disorders.
Collapse
Affiliation(s)
- Juanjiangmeng Du
- Cologne Center for Genomics, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Sean Simmons
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA; Analytic and Translational Genetics Unit, Massachusetts General Hospital, Cambridge, MA, USA
| | - Andreas Brunklaus
- The Paediatric Neurosciences Research Group, Royal Hospital for Children, Glasgow, UK; School of Medicine, University of Glasgow, Glasgow, UK.
| | - Xian Adiconis
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Cynthia C Hession
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Zhanyan Fu
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Yinqing Li
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Reut Shema
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Rikke S Møller
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Dianalund, Denmark; Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark
| | - Boaz Barak
- McGovern Institute for Brain Research and Department of Brain & Cognitive Sciences, MIT, Cambridge, MA, USA
| | - Guoping Feng
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA; McGovern Institute for Brain Research and Department of Brain & Cognitive Sciences, MIT, Cambridge, MA, USA
| | - Miriam Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA; Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Stephan Sanders
- Department of Psychiatry, UCSF Weill Institute for Neurosciences, University of California, San Francisco, CA, USA
| | - Holger Lerche
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Arthur J Campbell
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Steven McCarroll
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA; Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Joshua Z Levin
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Dennis Lal
- Cologne Center for Genomics, University of Cologne, University Hospital Cologne, Cologne, Germany; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA; Analytic and Translational Genetics Unit, Massachusetts General Hospital, Cambridge, MA, USA; Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH, USA; Genomic Medicine Institute, Lerner Research Institute Cleveland Clinic, Cleveland, OH, USA.
| |
Collapse
|
32
|
Recent advances in treatment of epilepsy-related sodium channelopathies. Eur J Paediatr Neurol 2020; 24:123-128. [PMID: 31889633 DOI: 10.1016/j.ejpn.2019.12.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 12/06/2019] [Indexed: 11/22/2022]
Abstract
Voltage-gated sodium channels (VGSCs) play a crucial role in generation of action potentials. Pathogenic variants in the five human brain expressed VGSC genes, SCN1A, SCN2A, SCN3A, SCN8A and SCN1B have been associated with a spectrum of epilepsy phenotypes and neurodevelopmental disorders. In the last decade, next generation sequencing techniques have revolutionized the way we diagnose these channelopathies, which is paving the way towards precision medicine. Knowing the functional effect (Loss-of-function versus Gain-of-function) of a variant is not only important for understanding the underlying pathophysiology, but it is particularly crucial to orient therapeutic decisions. Here we provide a review of the literature dealing with treatment options in epilepsy-related sodium channelopathies, including the current and emerging medications.
Collapse
|
33
|
Jansen NA, Dehghani A, Linssen MML, Breukel C, Tolner EA, van den Maagdenberg AMJM. First FHM3 mouse model shows spontaneous cortical spreading depolarizations. Ann Clin Transl Neurol 2019; 7:132-138. [PMID: 31880072 PMCID: PMC6952313 DOI: 10.1002/acn3.50971] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 12/07/2019] [Indexed: 01/19/2023] Open
Abstract
Here we show, for the first time, spontaneous cortical spreading depolarization (CSD) events - the electrophysiological correlate of the migraine aura - in animals by using the first generated familial hemiplegic migraine type 3 (FHM3) transgenic mouse model. The mutant mice express L263V-mutated α1 subunits in voltage-gated NaV 1.1 sodium channels (Scn1aL263V ). CSDs consistently propagated from visual to motor cortex, recapitulating what has been shown in patients with migraine with aura. This model may be valuable for the preclinical study of migraine with aura and other diseases in which spreading depolarization is a prominent feature.
Collapse
Affiliation(s)
- Nico A Jansen
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Anisa Dehghani
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Margot M L Linssen
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Cor Breukel
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Else A Tolner
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.,Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands
| | - Arn M J M van den Maagdenberg
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.,Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands
| |
Collapse
|
34
|
Barbieri R, Bertelli S, Pusch M, Gavazzo P. Late sodium current blocker GS967 inhibits persistent currents induced by familial hemiplegic migraine type 3 mutations of the SCN1A gene. J Headache Pain 2019; 20:107. [PMID: 31730442 PMCID: PMC6858687 DOI: 10.1186/s10194-019-1056-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 10/29/2019] [Indexed: 01/31/2023] Open
Abstract
Background Familial hemiplegic migraine (FHM) is a group of genetic migraine, associated with hemiparesis and aura. Three causative different genes have been identified, all of which are involved in membrane ion transport. Among these, SCN1A encodes the voltage-gated Na+ channel Nav1.1, and FHM caused by mutations of SCN1A is named FHM3. For 7 of the 12 known FHM3-causing SCNA1 mutations functional consequences have been investigated, and even if gain of function effect seems to be a predominant phenotype, for several mutations conflicting results have been obtained and the available data do not reveal a univocal FHM3 pathomechanism. Methods To obtain a more complete picture, here, we characterized by patch clamp approach the remaining 5 mutations (Q1489H, I1498M, F1499 L, M1500 V, F1661 L) in heterologous expression systems. Results With the exception of I1498M, all mutants exhibited the same current density as WT and exhibited a shift of the steady state inactivation to more positive voltages, an accelerated recovery from inactivation, and an increase of the persistent current, revealing that most FHM3 mutations induce a gain of function. We also determined the effect of GS967, a late Na+ current blocker, on the above mentioned mutants as well as on previously characterized ones (L1649Q, L1670 W, F1774S). GS967 inhibited persistent currents of all SCNA1 FMH3-related mutants and dramatically slowed the recovery from fast inactivation of WT and mutants, consistent with the hypothesis that GS967 specifically binds to and thereby stabilizes the fast inactivated state. Simulation of neuronal firing showed that enhanced persistent currents cause an increase of ionic fluxes during action potential repolarization and consequent accumulation of K+ and/or exhaustion of neuronal energy resources. In silico application of GS967 largely reduced net ionic currents in neurons without impairing excitability. Conclusion In conclusion, late Na+ current blockers appear a promising specific pharmacological treatment of FHM3.
Collapse
Affiliation(s)
- R Barbieri
- Biophysics Institute, National Research Council, Via De Marini 6, Genoa, Italy
| | - S Bertelli
- Biophysics Institute, National Research Council, Via De Marini 6, Genoa, Italy.,International School of Advanced Studies (SISSA), Via Bonomea, 265, Trieste, Italy
| | - M Pusch
- Biophysics Institute, National Research Council, Via De Marini 6, Genoa, Italy
| | - P Gavazzo
- Biophysics Institute, National Research Council, Via De Marini 6, Genoa, Italy.
| |
Collapse
|
35
|
Carvill GL, Dulla CG, Lowenstein DH, Brooks-Kayal AR. The path from scientific discovery to cures for epilepsy. Neuropharmacology 2019; 167:107702. [PMID: 31301334 DOI: 10.1016/j.neuropharm.2019.107702] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 07/05/2019] [Accepted: 07/06/2019] [Indexed: 02/06/2023]
Abstract
The epilepsies are a complex group of disorders that can be caused by a myriad of genetic and acquired factors. As such, identifying interventions that will prevent development of epilepsy, as well as cure the disorder once established, will require a multifaceted approach. Here we discuss the progress in scientific discovery propelling us towards this goal, including identification of genetic risk factors and big data approaches that integrate clinical and molecular 'omics' datasets to identify common pathophysiological signatures and biomarkers. We discuss the many animal and cellular models of epilepsy, what they have taught us about pathophysiology, and the cutting edge cellular, optogenetic, chemogenetic and anti-seizure drug screening approaches that are being used to find new cures in these models. Finally, we reflect on the work that still needs to be done towards identify at-risk individuals early, targeting and stopping epileptogenesis, and optimizing promising treatment approaches. Ultimately, developing and implementing cures for epilepsy will require a coordinated and immense effort from clinicians and basic scientists, as well as industry, and should always be guided by the needs of individuals affected by epilepsy and their families. This article is part of the special issue entitled 'New Epilepsy Therapies for the 21st Century - From Antiseizure Drugs to Prevention, Modification and Cure of Epilepsy'.
Collapse
Affiliation(s)
- Gemma L Carvill
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA.
| | - Chris G Dulla
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA.
| | - Dan H Lowenstein
- Department of Neurology, University of California, San Francisco, CA, 94941, USA
| | - Amy R Brooks-Kayal
- Department of Pediatrics and Neurology, University of Colorado School of Medicine and Children's Hospital Colorado, Aurora, CO, 80045, USA
| |
Collapse
|
36
|
Wengert ER, Saga AU, Panchal PS, Barker BS, Patel MK. Prax330 reduces persistent and resurgent sodium channel currents and neuronal hyperexcitability of subiculum neurons in a mouse model of SCN8A epileptic encephalopathy. Neuropharmacology 2019; 158:107699. [PMID: 31278928 DOI: 10.1016/j.neuropharm.2019.107699] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 06/25/2019] [Accepted: 07/01/2019] [Indexed: 11/28/2022]
Abstract
SCN8A epileptic encephalopathy is a severe genetic epilepsy syndrome caused by de novo gain-of-function mutations of SCN8A encoding the voltage-gated sodium (Na) channel (VGSC) NaV1.6. Therapeutic management is difficult in many patients, leading to uncontrolled seizures and risk of sudden unexpected death in epilepsy (SUDEP). There is a need to develop novel anticonvulsants that can specifically target aberrant VGSC activity associated with SCN8A gain-of-function mutations. In this study, we investigate the effects of Prax330, a novel VGSC inhibitor, on the biophysical properties of wild-type (WT) NaV1.6 and the patient mutation p.Asn1768Asp (N1768D) in ND7/23 cells. The effects of Prax330 on persistent (INaP) and resurgent (INaR) Na currents and neuronal excitability in subiculum neurons from a knock-in mouse model of the Scn8a-N1768D mutation (Scn8aD/+) were also examined. In ND7/23 cells, Prax330 reduced INaP currents recorded from cells expressing Scn8a-N1768D and hyperpolarized steady-state inactivation curves. Recordings from brain slices demonstrated elevated INaP and INaR in subiculum neurons from Scn8aD/+ mutant mice and abnormally large action potential (AP) burst-firing events in a subset of neurons. Prax330 (1 μM) reduced both INaP and INaR and suppressed AP bursts, with a smaller effect on AP waveforms that had similar morphology to WT neurons. Prax330 (1 μM) also reduced synaptically-evoked APs in Scn8aD/+ subiculum neurons but not in WT neurons. Our results highlight the efficacy of targeting INaP and INaR and inactivation parameters in controlling subiculum excitability and suggest Prax330 as a promising novel therapy for SCN8A epileptic encephalopathy.
Collapse
Affiliation(s)
- Eric R Wengert
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, 22908, USA; Neuroscience Graduate Program, University of Virginia Health System, Charlottesville, VA, 22908, USA
| | - Anusha U Saga
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, 22908, USA
| | - Payal S Panchal
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, 22908, USA
| | - Bryan S Barker
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, 22908, USA; Neuroscience Graduate Program, University of Virginia Health System, Charlottesville, VA, 22908, USA
| | - Manoj K Patel
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, 22908, USA; Neuroscience Graduate Program, University of Virginia Health System, Charlottesville, VA, 22908, USA.
| |
Collapse
|
37
|
Shi L, Zhu M, Li H, Wen Z, Chen X, Luo J, Lin C, Zhang Z. SCN1A and SCN2A polymorphisms are associated with response to valproic acid in Chinese epilepsy patients. Eur J Clin Pharmacol 2019; 75:655-663. [PMID: 30693367 DOI: 10.1007/s00228-019-02633-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 01/16/2019] [Indexed: 01/03/2023]
Abstract
PURPOSE There is a large inter-individual variation in the efficacy of valproic acid (VPA) against epilepsy. The genetic polymorphism influence of sodium channels on VPA response remains a matter of debate. The aim of the study was to explore the effect of SCN1A and SCN2A gene polymorphisms on VPA response in the treatment of epilepsy among Chinese patients. METHODS A total of 354 epileptic patients with VPA treatment were genotyped for five single nucleotide polymorphisms (SNP), including SCN1A rs10188577 T>C, rs2298771 T>C, rs3812718 G>A, and SCN2A rs2304016 A>G, rs17183814 G>A. A binary logistic regression analysis was performed to evaluate the association of genotype with VPA antiepileptic effects, adjusting the influence of confounding factors. RESULTS Genotype distributions of all selected SNPs were consistent with the Hardy-Weinberg equilibrium in epilepsy patients. SCN1A rs3812718 and SCN2A rs2304016 were found to be significantly associated with VPA response, both in monotherapy and in VPA-based polytherapy. Patients with the rs3812718 A allele were more frequently seen in the VPA-responsive group (P < 0.05), and the rs2304016 G allele was related to an increased risk of resistance to VPA therapy (P < 0.05). CONCLUSIONS Our study revealed that SCN1A rs3812718 and SCN2A rs2304016 polymorphisms might be markers of VPA response in Chinese epilepsy patients. TRIAL REGISTRATION ChiCTR-1800016477.
Collapse
Affiliation(s)
- Lihong Shi
- Department of Pharmacy, Xiangya Hospital, Central South University, No. 87 Xiangya Road, Changsha, 410008, Hunan, China.,Institute of Hospital Pharmacy, Central South University, No. 87 Xiangya Road, Changsha, 410008, Hunan, China
| | - Miaomiao Zhu
- Department of Pharmacy, Xiangya Hospital, Central South University, No. 87 Xiangya Road, Changsha, 410008, Hunan, China.,Institute of Hospital Pharmacy, Central South University, No. 87 Xiangya Road, Changsha, 410008, Hunan, China
| | - Huilan Li
- Department of Pharmacy, Xiangya Hospital, Central South University, No. 87 Xiangya Road, Changsha, 410008, Hunan, China.,Institute of Hospital Pharmacy, Central South University, No. 87 Xiangya Road, Changsha, 410008, Hunan, China
| | - Zhipeng Wen
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, No. 110 Xiangya Road, Changsha, 410008, China.,Institute of Clinical Pharmacology, Central South University, No. 110 Xiangya Road, Changsha, 410008, China
| | - Xiaoping Chen
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, No. 110 Xiangya Road, Changsha, 410008, China.,Institute of Clinical Pharmacology, Central South University, No. 110 Xiangya Road, Changsha, 410008, China
| | - Jia Luo
- Department of Pharmacy, Xiangya Hospital, Central South University, No. 87 Xiangya Road, Changsha, 410008, Hunan, China.,Institute of Hospital Pharmacy, Central South University, No. 87 Xiangya Road, Changsha, 410008, Hunan, China
| | - Cong Lin
- Department of Pharmacy, Xiangya Hospital, Central South University, No. 87 Xiangya Road, Changsha, 410008, Hunan, China.,Institute of Hospital Pharmacy, Central South University, No. 87 Xiangya Road, Changsha, 410008, Hunan, China
| | - Zanling Zhang
- Department of Pharmacy, Xiangya Hospital, Central South University, No. 87 Xiangya Road, Changsha, 410008, Hunan, China. .,Institute of Hospital Pharmacy, Central South University, No. 87 Xiangya Road, Changsha, 410008, Hunan, China.
| |
Collapse
|
38
|
Brigo F, Striano P, Balagura G, Belcastro V. Emerging drugs for the treatment of Dravet syndrome. Expert Opin Emerg Drugs 2018; 23:261-269. [DOI: 10.1080/14728214.2018.1552937] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Francesco Brigo
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
- Division of Neurology, “Franz Tappeiner” Hospital, Merano, Italy
| | - Pasquale Striano
- Pediatric Neurology and Muscular Diseases Unit, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, “G. Gaslini” Institute, Genova, Italy
| | - Ganna Balagura
- Pediatric Neurology and Muscular Diseases Unit, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, “G. Gaslini” Institute, Genova, Italy
| | | |
Collapse
|
39
|
Ghovanloo MR, Shuart NG, Mezeyova J, Dean RA, Ruben PC, Goodchild SJ. Inhibitory effects of cannabidiol on voltage-dependent sodium currents. J Biol Chem 2018; 293:16546-16558. [PMID: 30219789 PMCID: PMC6204917 DOI: 10.1074/jbc.ra118.004929] [Citation(s) in RCA: 123] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 09/12/2018] [Indexed: 12/25/2022] Open
Abstract
Cannabis sativa contains many related compounds known as phytocannabinoids. The main psychoactive and nonpsychoactive compounds are Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), respectively. Much of the evidence for clinical efficacy of CBD-mediated antiepileptic effects has been from case reports or smaller surveys. The mechanisms for CBD's anticonvulsant effects are unclear and likely involve noncannabinoid receptor pathways. CBD is reported to modulate several ion channels, including sodium channels (Nav). Evaluating the therapeutic mechanisms and safety of CBD demands a richer understanding of its interactions with central nervous system targets. Here, we used voltage-clamp electrophysiology of HEK-293 cells and iPSC neurons to characterize the effects of CBD on Nav channels. Our results show that CBD inhibits hNav1.1-1.7 currents, with an IC50 of 1.9-3.8 μm, suggesting that this inhibition could occur at therapeutically relevant concentrations. A steep Hill slope of ∼3 suggested multiple interactions of CBD with Nav channels. CBD exhibited resting-state blockade, became more potent at depolarized potentials, and also slowed recovery from inactivation, supporting the idea that CBD binding preferentially stabilizes inactivated Nav channel states. We also found that CBD inhibits other voltage-dependent currents from diverse channels, including bacterial homomeric Nav channel (NaChBac) and voltage-gated potassium channel subunit Kv2.1. Lastly, the CBD block of Nav was temperature-dependent, with potency increasing at lower temperatures. We conclude that CBD's mode of action likely involves 1) compound partitioning in lipid membranes, which alters membrane fluidity affecting gating, and 2) undetermined direct interactions with sodium and potassium channels, whose combined effects are loss of channel excitability.
Collapse
Affiliation(s)
- Mohammad-Reza Ghovanloo
- From the Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada and
- the Department of Cellular and Molecular Biology, Xenon Pharmaceuticals, Burnaby, British Columbia V5G 4W8, Canada
| | - Noah Gregory Shuart
- the Department of Cellular and Molecular Biology, Xenon Pharmaceuticals, Burnaby, British Columbia V5G 4W8, Canada
| | - Janette Mezeyova
- the Department of Cellular and Molecular Biology, Xenon Pharmaceuticals, Burnaby, British Columbia V5G 4W8, Canada
| | - Richard A Dean
- the Department of Cellular and Molecular Biology, Xenon Pharmaceuticals, Burnaby, British Columbia V5G 4W8, Canada
| | - Peter C Ruben
- From the Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada and
| | - Samuel J Goodchild
- the Department of Cellular and Molecular Biology, Xenon Pharmaceuticals, Burnaby, British Columbia V5G 4W8, Canada
| |
Collapse
|
40
|
Hawkins NA, Calhoun JD, Huffman AM, Kearney JA. Gene expression profiling in a mouse model of Dravet syndrome. Exp Neurol 2018; 311:247-256. [PMID: 30347190 DOI: 10.1016/j.expneurol.2018.10.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 09/11/2018] [Accepted: 10/18/2018] [Indexed: 11/18/2022]
Abstract
Dravet syndrome is a severe, early-onset epileptic encephalopathy frequently resulting from de novo mutations of SCN1A. Mice with heterozygous deletion of Scn1a (Scn1a+/-) model many features of Dravet syndrome, including spontaneous seizures and premature lethality. Scn1a+/- mice exhibit variable phenotype penetrance and expressivity dependent upon the strain background. On the 129S6/SvEvTac (129) strain, Scn1a+/- mice do not display an overt phenotype. However Scn1a+/- mice on the [129S6xB6]F1 strain (F1.Scn1a+/-) exhibit juvenile-onset spontaneous seizures and premature lethality. QTL mapping identified several modifier loci responsible for strain-dependent differences in survival of Scn1a+/- mice, but these loci do not account for all the observed phenotypic variance. Global RNA-seq analysis was performed to identify additional genes and pathways that may contribute to variable phenotypes. Hippocampal gene expression was analyzed in wild-type (WT) and Scn1a+/- mice on both F1 and 129 strains, at two time points during disease development. There were few gene expression differences between 129.WT and 129.Scn1a+/- mice and approximately 100 genes with small expression differences (6-36%) between F1.WT and F1.Scn1a+/- mice. Strain-specific gene expression differences were more pronounced, with dozens of genes with >1.5-fold expression differences between 129 and F1 strains. Age-specific and seizure-related gene expression differences were most prominent, with hundreds of genes with >2-fold differences in expression identified between groups with and without seizures, suggesting potential differences in developmental trajectory and/or homeostatic plasticity during disease onset. Global expression differences in the context of Scn1a deletion may account for strain-dependent variation in seizure susceptibility and survival observed in Scn1a+/- mice.
Collapse
Affiliation(s)
- Nicole A Hawkins
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Jeffrey D Calhoun
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Alexandra M Huffman
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Jennifer A Kearney
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
| |
Collapse
|
41
|
Gonçalves TC, Benoit E, Partiseti M, Servent D. The Na V1.7 Channel Subtype as an Antinociceptive Target for Spider Toxins in Adult Dorsal Root Ganglia Neurons. Front Pharmacol 2018; 9:1000. [PMID: 30233376 PMCID: PMC6131673 DOI: 10.3389/fphar.2018.01000] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 08/14/2018] [Indexed: 12/11/2022] Open
Abstract
Although necessary for human survival, pain may sometimes become pathologic if long-lasting and associated with alterations in its signaling pathway. Opioid painkillers are officially used to treat moderate to severe, and even mild, pain. However, the consequent strong and not so rare complications that occur, including addiction and overdose, combined with pain management costs, remain an important societal and economic concern. In this context, animal venom toxins represent an original source of antinociceptive peptides that mainly target ion channels (such as ASICs as well as TRP, CaV, KV and NaV channels) involved in pain transmission. The present review aims to highlight the NaV1.7 channel subtype as an antinociceptive target for spider toxins in adult dorsal root ganglia neurons. It will detail (i) the characteristics of these primary sensory neurons, the first ones in contact with pain stimulus and conveying the nociceptive message, (ii) the electrophysiological properties of the different NaV channel subtypes expressed in these neurons, with a particular attention on the NaV1.7 subtype, an antinociceptive target of choice that has been validated by human genetic evidence, and (iii) the features of spider venom toxins, shaped of inhibitory cysteine knot motif, that present high affinity for the NaV1.7 subtype associated with evidenced analgesic efficacy in animal models.
Collapse
Affiliation(s)
- Tânia C Gonçalves
- Sanofi R&D, Integrated Drug Discovery - High Content Biology, Paris, France.,Service d'Ingénierie Moléculaire des Protéines, CEA de Saclay, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Evelyne Benoit
- Service d'Ingénierie Moléculaire des Protéines, CEA de Saclay, Université Paris-Saclay, Gif-sur-Yvette, France.,Institut des Neurosciences Paris-Saclay, UMR CNRS/Université Paris-Sud 9197, Gif-sur-Yvette, France
| | - Michel Partiseti
- Sanofi R&D, Integrated Drug Discovery - High Content Biology, Paris, France
| | - Denis Servent
- Service d'Ingénierie Moléculaire des Protéines, CEA de Saclay, Université Paris-Saclay, Gif-sur-Yvette, France
| |
Collapse
|
42
|
Novel Quantitative Analyses of Spontaneous Synaptic Events in Cortical Pyramidal Cells Reveal Subtle Parvalbumin-Expressing Interneuron Dysfunction in a Knock-In Mouse Model of Alzheimer's Disease. eNeuro 2018; 5:eN-CFN-0059-18. [PMID: 30105300 PMCID: PMC6088364 DOI: 10.1523/eneuro.0059-18.2018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 06/19/2018] [Accepted: 06/24/2018] [Indexed: 12/19/2022] Open
Abstract
Alzheimer’s disease (AD) is a neurodegenerative disorder that has become a compelling global public health concern. Besides pathological hallmarks such as extracellular amyloid plaques, intracellular neurofibrillary tangles (NFTs), and loss of neurons and synapses, clinical reports have shown that epileptiform activity, even seizures, can occur early in the disease. Aberrant synaptic and network activities as well as epileptiform discharges have also been observed in various mouse models of AD. The new AppNL-F mouse model is generated by a gene knock-in approach and there are limited studies on basic synaptic properties in AppNL-F mice. Therefore, we applied quantitative methods to analyze spontaneous excitatory and inhibitory synaptic events in parietal cortex layer 2/3 pyramidal cells. First, by an objective amplitude distribution analysis, we found decreased amplitudes of spontaneous IPSCs (sIPSCs) in aged AppNL-F mice caused by a reduction in the amplitudes of the large sIPSCs with fast rates of rise, consistent with deficits in the function of parvalbumin-expressing interneurons (PV INs). Second, we calculated the burstiness and memory in a series of successive synaptic events. Lastly, by using a novel approach to determine the excitation-to-inhibition (E/I) ratio, we found no changes in the AppNL-F mice, indicating that homeostatic mechanisms may have maintained the overall balance of excitation and inhibition in spite of a mildly impaired PV IN function.
Collapse
|
43
|
A Transient Developmental Window of Fast-Spiking Interneuron Dysfunction in a Mouse Model of Dravet Syndrome. J Neurosci 2018; 38:7912-7927. [PMID: 30104343 DOI: 10.1523/jneurosci.0193-18.2018] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 07/12/2018] [Accepted: 07/17/2018] [Indexed: 01/06/2023] Open
Abstract
Dravet syndrome is a severe, childhood-onset epilepsy largely due to heterozygous loss-of-function mutation of the gene SCN1A, which encodes the type 1 neuronal voltage-gated sodium (Na+) channel α subunit Nav1.1. Prior studies in mouse models of Dravet syndrome (Scn1a+/- mice) indicate that, in cerebral cortex, Nav1.1 is predominantly expressed in GABAergic interneurons, in particular in parvalbumin-positive fast-spiking basket cell interneurons (PVINs). This has led to a model of Dravet syndrome pathogenesis in which Nav1.1 mutation leads to preferential dysfunction of interneurons, decreased synaptic inhibition, hyperexcitability, and epilepsy. However, such studies have been implemented at early developmental time points. Here, we performed electrophysiological recordings in acute brain slices prepared from male and female Scn1a+/- mice as well as age-matched wild-type littermate controls and found that, later in development, the excitability of PVINs had normalized. Analysis of action potential waveforms indirectly suggests a reorganization of axonal Na+ channels in PVINs from Scn1a+/- mice, a finding supported by immunohistochemical data showing elongation of the axon initial segment. Our results imply that transient impairment of action potential generation by PVINs may contribute to the initial appearance of epilepsy, but is not the mechanism of ongoing, chronic epilepsy in Dravet syndrome.SIGNIFICANCE STATEMENT Dravet syndrome is characterized by normal early development, temperature-sensitive seizures in infancy, progression to treatment-resistant epilepsy, developmental delay, autism, and sudden unexplained death due to mutation in SCN1A encoding the Na+ channel subunit Nav1.1. Prior work has revealed a preferential impact of Nav1.1 loss on the function of GABAergic inhibitory interneurons. However, such data derive exclusively from recordings of neurons in young Scn1a+/- mice. Here, we show that impaired action potential generation observed in parvalbumin-positive fast-spiking interneurons (PVINs) in Scn1a+/- mice during early development has normalized by postnatal day 35. This work suggests that a transient impairment of PVINs contributes to epilepsy onset, but is not the mechanism of ongoing, chronic epilepsy in Dravet syndrome.
Collapse
|
44
|
Griffin A, Hamling KR, Hong S, Anvar M, Lee LP, Baraban SC. Preclinical Animal Models for Dravet Syndrome: Seizure Phenotypes, Comorbidities and Drug Screening. Front Pharmacol 2018; 9:573. [PMID: 29915537 PMCID: PMC5994396 DOI: 10.3389/fphar.2018.00573] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 05/14/2018] [Indexed: 12/18/2022] Open
Abstract
Epilepsy is a common chronic neurological disease affecting almost 3 million people in the United States and 50 million people worldwide. Despite availability of more than two dozen FDA-approved anti-epileptic drugs (AEDs), one-third of patients fail to receive adequate seizure control. Specifically, pediatric genetic epilepsies are often the most severe, debilitating and pharmaco-resistant forms of epilepsy. Epileptic syndromes share a common symptom of unprovoked seizures. While some epilepsies/forms of epilepsy are the result of acquired insults such as head trauma, febrile seizure, or viral infection, others have a genetic basis. The discovery of epilepsy associated genes suggests varied underlying pathologies and opens the door for development of new "personalized" treatment options for each genetic epilepsy. Among these, Dravet syndrome (DS) has received substantial attention for both the pre-clinical and early clinical development of novel therapeutics. Despite these advances, there is no FDA-approved treatment for DS. Over 80% of patients diagnosed with DS carry a de novo mutation within the voltage-gated sodium channel gene SCN1A and these patients suffer with drug resistant and life-threatening seizures. Here we will review the preclinical animal models for DS featuring inactivation of SCN1A (including zebrafish and mice) with an emphasis on seizure phenotypes and behavioral comorbidities. Because many drugs fail somewhere between initial preclinical discovery and clinical trials, it is equally important that we understand how these models respond to known AEDs. As such, we will also review the available literature and recent drug screening efforts using these models with a focus on assay protocols and predictive pharmacological profiles. Validation of these preclinical models is a critical step in our efforts to efficiently discover new therapies for these patients. The behavioral and electrophysiological drug screening assays in zebrafish will be discussed in detail including specific examples from our laboratory using a zebrafish scn1 mutant and a summary of the nearly 3000 drugs screened to date. As the discovery and development phase rapidly moves from the lab-to-the-clinic for DS, it is hoped that this preclinical strategy offers a platform for how to approach any genetic epilepsy.
Collapse
Affiliation(s)
- Aliesha Griffin
- Epilepsy Research Laboratory Department of Neurological Surgery and Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, United States
| | - Kyla R Hamling
- Epilepsy Research Laboratory Department of Neurological Surgery and Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, United States
| | - SoonGweon Hong
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA, United States
| | - Mana Anvar
- Epilepsy Research Laboratory Department of Neurological Surgery and Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, United States
| | - Luke P Lee
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA, United States
| | - Scott C Baraban
- Epilepsy Research Laboratory Department of Neurological Surgery and Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, United States
| |
Collapse
|
45
|
Xie A, Gallant B, Guo H, Gonzalez A, Clark M, Madigan A, Feng F, Chen HD, Cui Y, Dudley SC, Wan Y. Functional cardiac Na + channels are expressed in human melanoma cells. Oncol Lett 2018; 16:1689-1695. [PMID: 30008854 PMCID: PMC6036419 DOI: 10.3892/ol.2018.8865] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 04/26/2018] [Indexed: 11/12/2022] Open
Abstract
Resting membrane potential (RMP) and intracellular Ca2+ concentration [(Ca2+)i] are involved in tumorigenesis and metastasis. The present study investigated whether functional cardiac Na+ channels are expressed in human melanoma cells (WM 266-4) and its nonmalignant human melanocytes (HMC), as well as whether they participate in RMP maintenance and Ca2+ homeostasis. Confocal microscopy and western blot analysis were used to detect Na+ channels. The patch-clamp technique was employed to record Na+ currents and action potentials. Cytoplasmic Ca2+ was measured by loading Fluo-4. Cardiac (Nav1.5) Na+ channels were expressed in HMCs and WM 266-4 cells. Tetrodotoxin (TTX) dose-dependently blocked Na+ currents in WM 266-4 while HMCs had no Na+ currents. Ultraviolet light induced similar action potentials in HMCs and WM 266-4 cells, which were abolished by transient receptor potential A1 channel-specific blocker, HC-030031. Compared with HMCs, RMP was substantially depolarized in WM 266-4. TTX hyperpolarized RMP in WM 266-4 cells at a concentration of 30 µM, which facilitated Ca2+ influx. Compared with HMCs, (Ca2+)i was significantly higher in WM 266-4 cells and was elevated by 30 µM TTX. Collectively, Cardiac Na+ channels depolarize RMP and inhibit Ca2+ uptake in melanoma cells possibly contributing to tumorigenesis and metastasis. Na+ channel agonists may be developed to treat melanoma such as WM 266-4.
Collapse
Affiliation(s)
- An Xie
- Lifespan Cardiovascular Institute, The Warren Alpert School of Medicine of Brown University and The Providence Veterans Administration Medical Center, Providence, RI 02903, USA.,Department of Medicine, Lillehei Heart Institute, University of Minnesota, Minneapolis, MN 55455, USA
| | - Benjamin Gallant
- Department of Biology, Providence College, Providence, RI 02918, USA
| | - Hao Guo
- Department of Dermatology, No. 1 Hospital of China Medical University, Shenyang 110001, P.R. China
| | - Alfredo Gonzalez
- Department of Biology, Providence College, Providence, RI 02918, USA
| | - Matthew Clark
- Department of Biology, Providence College, Providence, RI 02918, USA
| | - Audrey Madigan
- Department of Biology, Providence College, Providence, RI 02918, USA
| | - Feng Feng
- Department of Medicine, Lillehei Heart Institute, University of Minnesota, Minneapolis, MN 55455, USA
| | - Hong-Duo Chen
- Department of Dermatology, No. 1 Hospital of China Medical University, Shenyang 110001, P.R. China
| | - Yali Cui
- College of Life Science, Northwest University, Xi'an, Shaanxi 710069, P.R. China
| | - Samuel C Dudley
- Lifespan Cardiovascular Institute, The Warren Alpert School of Medicine of Brown University and The Providence Veterans Administration Medical Center, Providence, RI 02903, USA.,Department of Medicine, Lillehei Heart Institute, University of Minnesota, Minneapolis, MN 55455, USA
| | - Yinsheng Wan
- Department of Biology, Providence College, Providence, RI 02918, USA
| |
Collapse
|
46
|
Baker EM, Thompson CH, Hawkins NA, Wagnon JL, Wengert ER, Patel MK, George AL, Meisler MH, Kearney JA. The novel sodium channel modulator GS-458967 (GS967) is an effective treatment in a mouse model of SCN8A encephalopathy. Epilepsia 2018; 59:1166-1176. [PMID: 29782051 DOI: 10.1111/epi.14196] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/16/2018] [Indexed: 01/17/2023]
Abstract
OBJECTIVE De novo mutations of SCN8A, encoding the voltage-gated sodium channel NaV 1.6, have been associated with a severe infant onset epileptic encephalopathy. Individuals with SCN8A encephalopathy have a mean age of seizure onset of 4-5 months, with multiple seizure types that are often refractory to treatment with available drugs. Anecdotal reports suggest that high-dose phenytoin is effective for some patients, but there are associated adverse effects and potential for toxicity. Functional characterization of several SCN8A encephalopathy variants has shown that elevated persistent sodium current is one of several common biophysical defects. Therefore, specifically targeting elevated persistent current may be a useful therapeutic strategy in some cases. METHODS The novel sodium channel modulator GS967 has greater preference for persistent as opposed to peak current and nearly 10-fold greater potency than phenytoin. We evaluated the therapeutic effect of GS967 in the Scn8aN1768D/+ mouse model carrying an SCN8A patient mutation that results in elevated persistent sodium current. We also performed patch clamp recordings to assess the effect of GS967 on peak and persistent sodium current and excitability in hippocampal neurons from Scn8aN1768D/+ mice. RESULTS GS967 potently blocked persistent sodium current without affecting peak current, normalized action potential morphology, and attenuated excitability in neurons from heterozygous Scn8aN1768D/+ mice. Acute treatment with GS967 provided dose-dependent protection against maximal electroshock-induced seizures in Scn8aN1768D/+ and wild-type mice. Chronic treatment of Scn8aN1768D/+ mice with GS967 resulted in lower seizure burden and complete protection from seizure-associated lethality observed in untreated Scn8aN1768D/+ mice. Protection was achieved at a chronic dose that did not cause overt behavioral toxicity or sedation. SIGNIFICANCE Persistent sodium current modulators like GS967 may be an effective precision targeting strategy for SCN8A encephalopathy and other functionally similar channelopathies when elevated persistent sodium current is the primary dysfunction.
Collapse
Affiliation(s)
- Erin M Baker
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Christopher H Thompson
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Nicole A Hawkins
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Jacy L Wagnon
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Eric R Wengert
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, USA
| | - Manoj K Patel
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, USA
| | - Alfred L George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Miriam H Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Jennifer A Kearney
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| |
Collapse
|
47
|
Carpenter JC, Schorge S. The voltage-gated channelopathies as a paradigm for studying epilepsy-causing genes. CURRENT OPINION IN PHYSIOLOGY 2018. [DOI: 10.1016/j.cophys.2018.01.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
48
|
Abstract
Dravet Syndrome is a devastating childhood epilepsy disorder with high incidence of premature death plus comorbidities of ataxia, circadian rhythm disorder, impaired sleep quality, autistic-like social-interaction deficits and severe cognitive impairment. It is primarily caused by heterozygous loss-of-function mutations in the SCN1A gene that encodes brain voltage-gated sodium channel type-1, termed NaV1.1. Here I review experiments on mouse genetic models that implicate specific loss of sodium currents and action potential firing in GABAergic inhibitory interneurons as the fundamental cause of Dravet Syndrome. The resulting imbalance of excitatory to inhibitory neurotransmission in neural circuits causes both epilepsy and co-morbidities. Promising therapeutic approaches involving atypical sodium channel blockers, novel drug combinations, and cannabidiol give hope for improved outcomes for Dravet Syndrome patients.
Collapse
Affiliation(s)
- William A Catterall
- Department of Pharmacology, University of Washington, Seattle, WA 98195-7280 USA
| |
Collapse
|
49
|
Kim Y, Bravo E, Thirnbeck CK, Smith-Mellecker LA, Kim SH, Gehlbach BK, Laux LC, Zhou X, Nordli DR, Richerson GB. Severe peri-ictal respiratory dysfunction is common in Dravet syndrome. J Clin Invest 2018; 128:1141-1153. [PMID: 29329111 DOI: 10.1172/jci94999] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 01/04/2018] [Indexed: 11/17/2022] Open
Abstract
Dravet syndrome (DS) is a severe childhood-onset epilepsy commonly due to mutations of the sodium channel gene SCN1A. Patients with DS have a high risk of sudden unexplained death in epilepsy (SUDEP), widely believed to be due to cardiac mechanisms. Here we show that patients with DS commonly have peri-ictal respiratory dysfunction. One patient had severe and prolonged postictal hypoventilation during video EEG monitoring and died later of SUDEP. Mice with an Scn1aR1407X/+ loss-of-function mutation were monitored and died after spontaneous and heat-induced seizures due to central apnea followed by progressive bradycardia. Death could be prevented with mechanical ventilation after seizures were induced by hyperthermia or maximal electroshock. Muscarinic receptor antagonists did not prevent bradycardia or death when given at doses selective for peripheral parasympathetic blockade, whereas apnea, bradycardia, and death were prevented by the same drugs given at doses high enough to cross the blood-brain barrier. When given via intracerebroventricular infusion at a very low dose, a muscarinic receptor antagonist prevented apnea, bradycardia, and death. We conclude that SUDEP in patients with DS can result from primary central apnea, which can cause bradycardia, presumably via a direct effect of hypoxemia on cardiac muscle.
Collapse
Affiliation(s)
- YuJaung Kim
- Department of Neurology and.,Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa, USA
| | | | | | | | - Se Hee Kim
- Division of Pediatric Neurology, Northwestern University, Chicago, Illinois, USA
| | | | - Linda C Laux
- Division of Pediatric Neurology, Northwestern University, Chicago, Illinois, USA
| | | | - Douglas R Nordli
- Division of Pediatric Neurology, Northwestern University, Chicago, Illinois, USA
| | - George B Richerson
- Department of Neurology and.,Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa, USA.,Neurology Service, Veterans Affairs Medical Center, Iowa City, Iowa, USA
| |
Collapse
|
50
|
Oyrer J, Maljevic S, Scheffer IE, Berkovic SF, Petrou S, Reid CA. Ion Channels in Genetic Epilepsy: From Genes and Mechanisms to Disease-Targeted Therapies. Pharmacol Rev 2018; 70:142-173. [PMID: 29263209 DOI: 10.1124/pr.117.014456] [Citation(s) in RCA: 163] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 10/02/2017] [Indexed: 12/19/2022] Open
Abstract
Epilepsy is a common and serious neurologic disease with a strong genetic component. Genetic studies have identified an increasing collection of disease-causing genes. The impact of these genetic discoveries is wide reaching-from precise diagnosis and classification of syndromes to the discovery and validation of new drug targets and the development of disease-targeted therapeutic strategies. About 25% of genes identified in epilepsy encode ion channels. Much of our understanding of disease mechanisms comes from work focused on this class of protein. In this study, we review the genetic, molecular, and physiologic evidence supporting the pathogenic role of a number of different voltage- and ligand-activated ion channels in genetic epilepsy. We also review proposed disease mechanisms for each ion channel and highlight targeted therapeutic strategies.
Collapse
Affiliation(s)
- Julia Oyrer
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Snezana Maljevic
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Ingrid E Scheffer
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Samuel F Berkovic
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Steven Petrou
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| | - Christopher A Reid
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia (J.O., S.M., I.E.S., S.P., C.A.R.); Department of Medicine, Austin Health, University of Melbourne, Heidelberg West, Melbourne, Australia (I.E.S., S.F.B.); and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia (I.E.S.)
| |
Collapse
|