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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.
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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
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2
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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.
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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
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Morais A, Qin T, Ayata C, Harriott AM. Inhibition of persistent sodium current reduces spreading depression-evoked allodynia in a mouse model of migraine with aura. Pain 2023; 164:2564-2571. [PMID: 37318029 DOI: 10.1097/j.pain.0000000000002962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 04/18/2023] [Indexed: 06/16/2023]
Abstract
ABSTRACT We investigated the efficacy of inhibiting persistent Na + currents (I NaP ) in acute rodent models of migraine with aura. Cortical spreading depression (SD) is a slow wave of neuronal and glial depolarization that underlies the migraine aura. Minimally invasive optogenetic SD (opto-SD) causes periorbital mechanical allodynia in mice, suggesting SD activates trigeminal nociceptors. Persistent Na + currents contribute to neuronal intrinsic excitability and have been implicated in peripheral and cortical excitation. We examined a preferential inhibitor of I NaP, GS-458967, on SD-induced periorbital allodynia, SD susceptibility, and formalin-induced peripheral pain. Periorbital mechanical allodynia was tested in male and female Thy1-ChR2-YFP mice after a single opto-SD event using manual von Frey monofilaments. GS-458967 (1 mg/kg, s.c.) or vehicle was dosed immediately after opto-SD induction, and allodynia was tested 1 hour later. The electrical SD threshold and KCl-induced SD frequency were examined in the cortex in male Sprague-Dawley rats after 1 hour pretreatment with GS-458967 (3 mg/kg, s.c.) or vehicle. Effects of GS-458967 (0.5-5 mg/kg, p.o.) on spontaneous formalin hind paw behavior and locomotion were also examined in male CD-1 mice. GS-458967 suppressed opto-SD-induced periorbital allodynia and decreased susceptibility to SD. GS-458967 also diminished early and late phase formalin-induced paw-licking behavior with early phase paw licking responding to lower doses. GS-458967 up to 3 mg/kg had no impact on locomotor activity. These data provide evidence that I NaP inhibition can reduce opto-SD-induced trigeminal pain behavior and support I NaP inhibition as an antinociceptive strategy for both abortive and preventive treatment of migraine.
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Affiliation(s)
- Andreia Morais
- Neurovascular Research Unit, Department of Radiology, Massachusetts General Hospital, Boston, MA, United States
| | - Tao Qin
- Neurovascular Research Unit, Department of Radiology, Massachusetts General Hospital, Boston, MA, United States
| | - Cenk Ayata
- Neurovascular Research Unit, Department of Radiology, Massachusetts General Hospital, Boston, MA, United States
- Department of Neurology, Massachusetts General Hospital, Boston, MA, United States
- Harvard Medical School, Boston, MA, United States
| | - Andrea M Harriott
- Neurovascular Research Unit, Department of Radiology, Massachusetts General Hospital, Boston, MA, United States
- Department of Neurology, Massachusetts General Hospital, Boston, MA, United States
- Harvard Medical School, Boston, MA, United States
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4
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Brunklaus A, Feng T, Brünger T, Perez-Palma E, Heyne H, Matthews E, Semsarian C, Symonds JD, Zuberi SM, Lal D, Schorge S. Gene variant effects across sodium channelopathies predict function and guide precision therapy. Brain 2022; 145:4275-4286. [PMID: 35037686 PMCID: PMC9897196 DOI: 10.1093/brain/awac006] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 11/27/2021] [Accepted: 12/10/2021] [Indexed: 11/14/2022] Open
Abstract
Pathogenic variants in the voltage-gated sodium channel gene family lead to early onset epilepsies, neurodevelopmental disorders, skeletal muscle channelopathies, peripheral neuropathies and cardiac arrhythmias. Disease-associated variants have diverse functional effects ranging from complete loss-of-function to marked gain-of-function. Therapeutic strategy is likely to depend on functional effect. Experimental studies offer important insights into channel function but are resource intensive and only performed in a minority of cases. Given the evolutionarily conserved nature of the sodium channel genes, we investigated whether similarities in biophysical properties between different voltage-gated sodium channels can predict function and inform precision treatment across sodium channelopathies. We performed a systematic literature search identifying functionally assessed variants in any of the nine voltage-gated sodium channel genes until 28 April 2021. We included missense variants that had been electrophysiologically characterized in mammalian cells in whole-cell patch-clamp recordings. We performed an alignment of linear protein sequences of all sodium channel genes and correlated variants by their overall functional effect on biophysical properties. Of 951 identified records, 437 sodium channel-variants met our inclusion criteria and were reviewed for functional properties. Of these, 141 variants were epilepsy-associated (SCN1/2/3/8A), 79 had a neuromuscular phenotype (SCN4/9/10/11A), 149 were associated with a cardiac phenotype (SCN5/10A) and 68 (16%) were considered benign. We detected 38 missense variant pairs with an identical disease-associated variant in a different sodium channel gene. Thirty-five out of 38 of those pairs resulted in similar functional consequences, indicating up to 92% biophysical agreement between corresponding sodium channel variants (odds ratio = 11.3; 95% confidence interval = 2.8 to 66.9; P < 0.001). Pathogenic missense variants were clustered in specific functional domains, whereas population variants were significantly more frequent across non-conserved domains (odds ratio = 18.6; 95% confidence interval = 10.9-34.4; P < 0.001). Pore-loop regions were frequently associated with loss-of-function variants, whereas inactivation sites were associated with gain-of-function (odds ratio = 42.1, 95% confidence interval = 14.5-122.4; P < 0.001), whilst variants occurring in voltage-sensing regions comprised a range of gain- and loss-of-function effects. Our findings suggest that biophysical characterisation of variants in one SCN-gene can predict channel function across different SCN-genes where experimental data are not available. The collected data represent the first gain- versus loss-of-function topological map of SCN proteins indicating shared patterns of biophysical effects aiding variant analysis and guiding precision therapy. We integrated our findings into a free online webtool to facilitate functional sodium channel gene variant interpretation (http://SCN-viewer.broadinstitute.org).
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Affiliation(s)
- Andreas Brunklaus
- Correspondence to: Dr Andreas Brunklaus, MD Fraser of Allander Neurosciences Unit Office Block, Ground Floor, Zone 2 Royal Hospital for Children 1345 Govan Road Glasgow G51 4TF, UK E-mail:
| | | | | | - Eduardo Perez-Palma
- Centro de Genética y Genómica, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago, Chile
| | - Henrike Heyne
- Genomic and Personalized Medicine, Digital Health Center, Hasso Plattner Institute, Potsdam, Germany
- Hasso Plattner Institute, Mount Sinai School of Medicine, New York, NY, USA
- Institute for Molecular Medicine Finland: FIMM, Helsinki, Finland
| | - Emma Matthews
- Atkinson Morley Neuromuscular Centre, St George’s University Hospitals NHS Foundation Trust, London, UK
- Molecular and Clinical Sciences Research Institute, St George’s University of London, London, UK
| | - Christopher Semsarian
- Agnes Ginges Centre for Molecular Cardiology at Centenary Institute, The University of Sydney, Sydney, Australia
- Sydney Medical School Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- Department of Cardiology, Royal Prince Alfred Hospital, Sydney, Australia
| | - Joseph D Symonds
- The Paediatric Neurosciences Research Group, Royal Hospital for Children, Glasgow, UK
- Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK
| | - Sameer M Zuberi
- The Paediatric Neurosciences Research Group, Royal Hospital for Children, Glasgow, UK
- Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK
| | - Dennis Lal
- Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, USA
- Stanley Center for Psychiatric Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Stephanie Schorge
- Correspondence may also be addressed to: Professor Stephanie Schorge, PhD Department of Neuroscience Physiology and Pharmacology UCL, London WC1E 6BT, UK E-mail:
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Borowicz-Reutt K, Banach M. Ranolazine Interacts Antagonistically with Some Classical Antiepileptic Drugs-An Isobolographic Analysis. Molecules 2022; 27:molecules27248955. [PMID: 36558088 PMCID: PMC9784994 DOI: 10.3390/molecules27248955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/13/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Ranolazine, an antianginal and antiarrhythmic drug blocking slow inactivating persistent sodium currents, is described as a compound with anticonvulsant potential. Since arrhythmia often accompanies seizures, patients suffering from epilepsy are frequently co-treated with antiepileptic and antiarrhythmic drugs. The aim of this study was to evaluate the effect of ranolazine on maximal-electroshock (MES)-induced seizures in mice as well as interactions between ranolazine and classical antiepileptic drugs in this model of epilepsy. Types of pharmacodynamic interactions were established by isobolographic analysis of obtained data. The main findings of the study were that ranolazine behaves like an antiseizure drug in the MES test. Moreover, ranolazine interacted antagonistically with carbamazepine, phenytoin, and phenobarbital in the proportions of 1:3 and 1:1. These interactions occurred pharmacodynamic, since ranolazine did not change the brain levels of antiepileptic drugs measured in the fluorescence polarization immunoassay. Ranolazine and its combinations with carbamazepine, phenytoin, and phenobarbital did not impair motor coordination evaluated in the chimney test. Unfortunately, an attempt to conduct a passive avoidance task (evaluating long-term memory) resulted in ranolazine-induced delayed lethality. In conclusion, ranolazine exhibits clear-cut anticonvulsant properties in the MES test but interacts antagonistically with some antiepileptic drugs. The obtained results need confirmation in clinical studies. The mechanisms of ranolazine-induced toxicity require specific explanation.
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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.
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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
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Smith MC, Klein P, Krauss GL, Rashid S, Seiden LG, Stern JM, Rosenfeld WE. Dose Adjustment of Concomitant Antiseizure Medications During Cenobamate Treatment: Expert Opinion Consensus Recommendations. Neurol Ther 2022; 11:1705-1720. [PMID: 36057761 PMCID: PMC9588096 DOI: 10.1007/s40120-022-00400-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 08/15/2022] [Indexed: 01/20/2023] Open
Abstract
INTRODUCTION Our objective was to provide expert consensus recommendations to improve treatment tolerability through dose adjustments of concomitant antiseizure medications (ASMs) during addition of cenobamate to existing ASM therapy in adult patients with uncontrolled focal seizures. METHODS A panel of seven epileptologists experienced in the use of ASMs, including cenobamate, used a modified Delphi process to reach consensus. The panelists discussed tolerability issues with concomitant ASMs during cenobamate titration and practical strategies for dose adjustments that may prevent or mitigate adverse effects. The resulting recommendations consider concomitant ASM dose level and specify proactive (prior to report of an adverse effect) and reactive (in response to report of an adverse effect) dose adjustment suggestions based on concomitant ASM pharmacokinetic and pharmacodynamic interactions with cenobamate. Specific dose adjustment recommendations are provided. RESULTS We recommend proactively lowering the dose of clobazam, phenytoin, and phenobarbital due to their known drug-drug interactions with cenobamate, and lacosamide due to a pharmacodynamic interaction with cenobamate, to prevent adverse effects during cenobamate titration. Reactive lowering of a concomitant ASM dose is sufficient for other ASMs at standard dosing owing to quick resolution of adverse effects. For carbamazepine and lamotrigine doses exceeding the upper end of standard dosing (e.g., carbamazepine, greater than 1200 mg/day; lamotrigine, greater than 500 mg/day), we encourage consideration of proactive dose reduction at cenobamate 200 mg/day to prevent potential adverse effects. All dose reductions for adverse effects can be repeated every 2 weeks as dictated by the adverse effects. At cenobamate 200 mg/day, we recommend that patients be evaluated for marked improvement of seizures and further dose reductions be considered to reduce potentially unnecessary polypharmacy. CONCLUSION The primary goal of the recommended dose reductions of concomitant ASMs is to prevent or resolve adverse effects, thereby allowing cenobamate to reach the optimal dose to achieve the maximal potential of improving seizure control.
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Affiliation(s)
- Michael C. Smith
- Department of Neurological Sciences, Section of Clinical Neurophysiology and Epilepsy, Rush Medical College, 1725 W. Harrison Street, Suite 885, Chicago, IL 60612 USA
| | - Pavel Klein
- Mid-Atlantic Epilepsy and Sleep Center, Bethesda, MD USA
| | | | - Samiya Rashid
- Epilepsy and Neurology Specialists of San Diego, Encinitas, CA USA
| | | | - John M. Stern
- University of California at Los Angeles, Los Angeles, CA USA
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Cervantes DO, Pizzo E, Ketkar H, Parambath SP, Tang S, Cianflone E, Cannata A, Vinukonda G, Jain S, Jacobson JT, Rota M. Scn1b expression in the adult mouse heart modulates Na + influx in myocytes and reveals a mechanistic link between Na + entry and diastolic function. Am J Physiol Heart Circ Physiol 2022; 322:H975-H993. [PMID: 35394857 PMCID: PMC9076421 DOI: 10.1152/ajpheart.00465.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 03/09/2022] [Accepted: 03/23/2022] [Indexed: 11/22/2022]
Abstract
Voltage-gated sodium channels (VGSCs) are macromolecular assemblies composed of a number of proteins regulating channel conductance and properties. VGSCs generate Na+ current (INa) in myocytes and play fundamental roles in excitability and impulse conduction in the heart. Moreover, VGSCs condition mechanical properties of the myocardium, a process that appears to involve the late component of INa. Variants in the gene SCN1B, encoding the VGSC β1- and β1B-subunits, result in inherited neurological disorders and cardiac arrhythmias. But the precise contributions of β1/β1B-subunits and VGSC integrity to the overall function of the adult heart remain to be clarified. For this purpose, adult mice with cardiac-restricted, inducible deletion of Scn1b (conditional knockout, cKO) were studied. Myocytes from cKO mice had increased densities of fast (+20%)- and slow (+140%)-inactivating components of INa, with respect to control cells. By echocardiography and invasive hemodynamics, systolic function was preserved in cKO mice, but diastolic properties and ventricular compliance were compromised, with respect to control animals. Importantly, inhibition of late INa with GS967 normalized left ventricular filling pattern and isovolumic relaxation time in cKO mice. At the cellular level, cKO myocytes presented delayed kinetics of Ca2+ transients and cell mechanics, defects that were corrected by inhibition of INa. Collectively, these results document that VGSC β1/β1B-subunits modulate electrical and mechanical function of the heart by regulating, at least in part, Na+ influx in cardiomyocytes.NEW & NOTEWORTHY We have investigated the consequences of deletion of Scn1b, the gene encoding voltage-gated sodium channel β1-subunits, on myocyte and cardiac function. Our findings support the notion that Scn1b expression controls properties of Na+ influx and Ca2+ cycling in cardiomyocytes affecting the modality of cell contraction and relaxation. These effects at the cellular level condition electrical recovery and diastolic function in vivo, substantiating the multifunctional role of β1-subunits in the physiology of the heart.
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Affiliation(s)
| | - Emanuele Pizzo
- Department of Physiology, New York Medical College, Valhalla, New York
| | - Harshada Ketkar
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, New York
| | - Sreema P Parambath
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, New York
| | - Samantha Tang
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, New York
| | - Eleonora Cianflone
- Department of Physiology, New York Medical College, Valhalla, New York
- Molecular and Cellular Cardiology, Department of Medical and Surgical Sciences, Magna Graecia University, Catanzaro, Italy
| | - Antonio Cannata
- School of Cardiovascular Medicine and Sciences, King's College London British Heart Foundation Centre of Excellence, London, United Kingdom
| | | | - Sudhir Jain
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, New York
| | - Jason T Jacobson
- Department of Physiology, New York Medical College, Valhalla, New York
- Department of Cardiology, Westchester Medical Center, Valhalla, New York
| | - Marcello Rota
- Department of Physiology, New York Medical College, Valhalla, New York
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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.
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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;
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10
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Milder PC, Zybura AS, Cummins TR, Marrs JA. Neural Activity Correlates With Behavior Effects of Anti-Seizure Drugs Efficacy Using the Zebrafish Pentylenetetrazol Seizure Model. Front Pharmacol 2022; 13:836573. [PMID: 35496264 PMCID: PMC9041662 DOI: 10.3389/fphar.2022.836573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 03/03/2022] [Indexed: 11/29/2022] Open
Abstract
Approximately 30% of patients with epilepsy do not achieve adequate seizure control through current anti-seizure drugs and treatment methods. Therefore, a critical need exists to efficiently screen anti-seizure drugs to enhance our ability to tailor treatment protocols and improve patient outcomes. The zebrafish pentylenetetrazol (PTZ) seizure model has become an increasingly popular screening paradigm for novel anti-seizure compounds. However, previous research using this model was variable due to differing experimental methods. Here, we present a method that was optimized to improve reliability and reproducibility in our laboratory using this PTZ model to develop a more robust screening of anti-seizure drugs comparing behavior and neural activity. Our behavior assay, spanning 90 min using 10 mM PTZ on 7 days post fertilization zebrafish, provides a broad window to observe anti-seizure drug efficacy. To compare our method with previously published data, we tested carbamazepine, lamotrigine, and topiramate, which have been tested in previous PTZ zebrafish assays. In addition, we assessed the candidate anti-seizure compound GS967, which has not been previously tested in the zebrafish seizure model. We examined the efficacy of anti-seizure drugs by acute administration concurrent with PTZ application and by pretreatment prior to exposure with PTZ. Pretreatment permitted us to examine potential neuroprotection and determine whether treatment time affects anti-seizure drugs’ responses. As independent validation of anti-seizure drugs’ effects, we evaluated whether the anti-seizure drug efficacy in the behavioral assay correlated with neural activity measurements, using electroencephalogram (EEG) and calcium signaling using GCaMP. There was no significant difference in the reduction of PTZ-induced seizure behavior activity between the pretreatment groups and acute treatment groups. Acute treatment with anti-seizure drugs in the EEG and GCaMP assays from 15 to 30 min post-anti-seizure drug exposure revealed consistent results between behavioral, EEG, and GCaMP assays for two of the three anti-seizure drugs. Lamotrigine only reduced neural activity (EEG and GCaMP assays). Carbamazepine, topiramate, and GS967 reduced activity in all three assays. The findings show that EEG and GCaMP assays largely correlate with the behavior findings, helping us connect physiological and behavior responses to anti-seizure drug and better assess anti-seizure drug efficacy.
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Darpo B, Sager PT, Xue H, Kamin M. A Phase 1 Clinical Study Evaluating the Effects of Cenobamate on the QT Interval. Clin Pharmacol Drug Dev 2022; 11:523-534. [PMID: 35182037 DOI: 10.1002/cpdd.1077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 12/27/2021] [Indexed: 11/12/2022]
Abstract
Cenobamate is an antiseizure medication for uncontrolled focal seizures. This thorough QT study assessed the effects of therapeutic and supratherapeutic cenobamate doses (maximum recommended dose, 400 mg/day) on correct QT interval (QTc) in healthy adults (N = 108) randomly assigned to 1 of 3 treatments: (A) cenobamate (days 1-63) up-titrated by 50-mg increments weekly to a 200 mg/day therapeutic dose (day 35) and then by 100 mg weekly to a 500 mg/day supratherapeutic dose (day 63), with placebo-moxifloxacin (days -1 and 64); (B) moxifloxacin 400 mg (day -1; positive control), placebo-cenobamate (days 1-63), and placebo-moxifloxacin (day 64); and (C) placebo-moxifloxacin (day -1), placebo-cenobamate (days 1-64), and moxifloxacin 400 mg (day 64). The primary end point was baseline-adjusted, placebo-corrected QTc (ΔΔQTcF; corrected for heart rate [HR] by Fridericia's method) with cenobamate 200 and 500 mg/day. Baseline electrocardiographic parameters were balanced across groups. Mean ΔΔQTcF was negative throughout for cenobamate doses (largest: day 35, -10.8 milliseconds; day 63, -18.4 milliseconds). Based on concentration-QTc analysis, ∆∆QTcF effect was predicted as -9.85 and -17.14 milliseconds at mean peak plasma levels of therapeutic (200 mg/day; 23.06 μg/mL) and supratherapeutic (500 mg/day; 63.96 μg/mL) doses. Cenobamate had no clinically relevant prolonging effect on electrocardiographic parameters (eg, PR, QRS); HR effects were similar to placebo. Cenobamate showed slight dose-related shortening of QTc, but to a degree not known to be clinically relevant (no reductions ≤340 milliseconds). Cenobamate had no clinically relevant effects on HR or electrocardiographic parameters and no QTc-prolonging effect at therapeutic/supratherapeutic doses. Cenobamate is contraindicated in patients with short-QT syndrome and caution should be used when coadministering with drugs that shorten QT interval.
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Affiliation(s)
| | - Philip T Sager
- Cardiovascular Research Institute and Department of Medicine, Stanford University, Palo Alto, California, USA
| | | | - Marc Kamin
- SK Life Science, Inc., Paramus, New Jersey, USA
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12
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Efficacy and safety of adjunctive cenobamate: post-hoc analysis of study C017 in patients grouped by mechanism of action of concomitant antiseizure medications. Seizure 2022; 96:86-93. [DOI: 10.1016/j.seizure.2022.02.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 02/04/2022] [Accepted: 02/06/2022] [Indexed: 11/22/2022] Open
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13
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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.
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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
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14
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Teran FA, Bravo E, Richerson GB. Sudden unexpected death in epilepsy: Respiratory mechanisms. HANDBOOK OF CLINICAL NEUROLOGY 2022; 189:153-176. [PMID: 36031303 PMCID: PMC10191258 DOI: 10.1016/b978-0-323-91532-8.00012-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Epilepsy is one of the most common chronic neurologic diseases, with a prevalence of 1% in the US population. Many people with epilepsy live normal lives, but are at risk of sudden unexpected death in epilepsy (SUDEP). This mysterious comorbidity of epilepsy causes premature death in 17%-50% of those with epilepsy. Most SUDEP occurs after a generalized seizure, and patients are typically found in bed in the prone position. Until recently, it was thought that SUDEP was due to cardiovascular failure, but patients who died while being monitored in hospital epilepsy units revealed that most SUDEP is due to postictal central apnea. Some cases may occur when seizures invade the amygdala and activate projections to the brainstem. Evidence suggests that the pathophysiology is linked to defects in the serotonin system and central CO2 chemoreception, and that there is considerable overlap with mechanisms thought to be involved in sudden infant death syndrome (SIDS). Future work is needed to identify biomarkers for patients at highest risk, improve ascertainment, develop methods to alert caregivers when SUDEP is imminent, and find effective approaches to prevent these fatal events.
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Affiliation(s)
- Frida A Teran
- Department of Neurology, University of Iowa, Iowa City, IA, United States; Medical Scientist Training Program, University of Iowa, Iowa City, IA, United States.
| | - Eduardo Bravo
- Department of Neurology, University of Iowa, Iowa City, IA, United States
| | - George B Richerson
- Department of Neurology, University of Iowa, Iowa City, IA, United States; Department of Molecular Physiology & Biophysics, University of Iowa, Iowa City, IA, United States
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15
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Ranolazine: An Old Drug with Emerging Potential; Lessons from Pre-Clinical and Clinical Investigations for Possible Repositioning. Pharmaceuticals (Basel) 2021; 15:ph15010031. [PMID: 35056088 PMCID: PMC8777683 DOI: 10.3390/ph15010031] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 12/16/2021] [Accepted: 12/20/2021] [Indexed: 02/07/2023] Open
Abstract
Ischemic heart disease is a significant public health problem with high mortality and morbidity. Extensive scientific investigations from basic sciences to clinics revealed multilevel alterations from metabolic imbalance, altered electrophysiology, and defective Ca2+/Na+ homeostasis leading to lethal arrhythmias. Despite the recent identification of numerous molecular targets with potential therapeutic interest, a pragmatic observation on the current pharmacological R&D output confirms the lack of new therapeutic offers to patients. By contrast, from recent trials, molecules initially developed for other fields of application have shown cardiovascular benefits, as illustrated with some anti-diabetic agents, regardless of the presence or absence of diabetes, emphasizing the clear advantage of “old” drug repositioning. Ranolazine is approved as an antianginal agent and has a favorable overall safety profile. This drug, developed initially as a metabolic modulator, was also identified as an inhibitor of the cardiac late Na+ current, although it also blocks other ionic currents, including the hERG/Ikr K+ current. The latter actions have been involved in this drug’s antiarrhythmic effects, both on supraventricular and ventricular arrhythmias (VA). However, despite initial enthusiasm and promising development in the cardiovascular field, ranolazine is only authorized as a second-line treatment in patients with chronic angina pectoris, notwithstanding its antiarrhythmic properties. A plausible reason for this is the apparent difficulty in linking the clinical benefits to the multiple molecular actions of this drug. Here, we review ranolazine’s experimental and clinical knowledge on cardiac metabolism and arrhythmias. We also highlight advances in understanding novel effects on neurons, the vascular system, skeletal muscles, blood sugar control, and cancer, which may open the way to reposition this “old” drug alone or in combination with other medications.
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16
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Sander JW, Rosenfeld WE, Halford JJ, Steinhoff BJ, Biton V, Toledo M. Long-term individual retention with cenobamate in adults with focal seizures: Pooled data from the clinical development program. Epilepsia 2021; 63:139-149. [PMID: 34813673 PMCID: PMC9299487 DOI: 10.1111/epi.17134] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 11/05/2021] [Accepted: 11/10/2021] [Indexed: 11/30/2022]
Abstract
Objective We determined retention on open‐label cenobamate therapy in the clinical development program to assess the long‐term efficacy and tolerability of adjunctive cenobamate in individuals with uncontrolled focal seizures. Methods Data from two randomized, controlled cenobamate studies and one open‐label safety and pharmacokinetic study were pooled. Based on the percentage of participants remaining on treatment, retention rates were estimated using Kaplan‐Meier survival analyses. We performed two additional analyses to assess factors contributing to retention, stratifying a robust data set (through 2 years) by cenobamate modal dose and frequently used concomitant anti‐seizure medications. Cenobamate discontinuations and treatment‐emergent adverse events were summarized. Results Data from 1844 participants were pooled: 149 from a single‐dose randomized trial, 355 from a multi‐dose randomized trial, and 1340 from an open‐label safety and pharmacokinetic study. Most participants from randomized trials continued in open‐label extensions, and pooled data represent >95% of participants exposed to cenobamate. Baseline characteristics and disease and treatment histories were similar across studies. Median duration of cenobamate exposure was 34 months, with a median modal dose of 200 mg/day. Kaplan‐Meier estimates of cumulative cenobamate retention rates were 80% at 1 year and 72% at 2 years. Once participants reached the maintenance phase, retention rates were consistently high in participants receiving ≥100 mg/day cenobamate, and concomitant anti‐seizure medications did not affect long‐term retention. By 2 years, 535 (29%) had actually discontinued cenobamate; the most common reasons for discontinuation were adverse events (37.6%), withdrawal of consent (21.1%), and other (16.8%). Significance Treatment retention rates provide a proxy measure for long‐term efficacy, safety, tolerability, and adherence. The consistently high retention rates we found suggest that cenobamate may be an effective and well‐tolerated new treatment option for people with drug‐resistant focal seizures.
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Affiliation(s)
- Josemir W Sander
- NIHR University College London Hospitals Biomedical Research Centre, UCL Queen Square Institute of Neurology, London, UK.,Chalfont Centre for Epilepsy, Chalfont St. Peter, UK.,Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, The Netherlands
| | - William E Rosenfeld
- Comprehensive Epilepsy Care Center for Children and Adults, St. Louis, Missouri, USA
| | - Jonathan J Halford
- Comprehensive Epilepsy Center, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Bernhard J Steinhoff
- Department of Neurology and Clinical Neurophysiology, Kork Epilepsy Center, Kehl-Kork, Germany.,Clinic for Neurology and Neurophysiology, Freiburg, Germany
| | - Victor Biton
- Arkansas Epilepsy Program, Little Rock, Arkansas, USA
| | - Manuel Toledo
- Epilepsy Unit, Neurology Department, Hospital Universitari Vall d'Hebron, Barcelona, Spain
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17
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Rosenfeld WE, Abou-Khalil B, Aboumatar S, Bhatia P, Biton V, Krauss GL, Sperling MR, Vossler DG, Klein P, Wechsler R. Post hoc analysis of a phase 3, multicenter, open-label study of cenobamate for treatment of uncontrolled focal seizures: Effects of dose adjustments of concomitant antiseizure medications. Epilepsia 2021; 62:3016-3028. [PMID: 34633074 PMCID: PMC9292883 DOI: 10.1111/epi.17092] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 09/23/2021] [Accepted: 09/23/2021] [Indexed: 01/23/2023]
Abstract
Objective To report post hoc results on how adjustments to baseline antiseizure medications (ASMs) in a subset of study sites (10 US sites) from a long‐term, open‐label phase 3 study of adjunctive cenobamate affected tolerability, efficacy, and retention. Methods Patients with uncontrolled focal seizures taking stable doses of one to three ASMs were administered increasing doses of cenobamate (12.5, 25, 50, 100, 150, 200 mg/day) over 12 weeks at 2‐week intervals (target dose = 200 mg/day). Further increases to 400 mg/day by 50 mg/day biweekly increments were allowed during maintenance phase. Dose adjustments of cenobamate and concomitant ASMs were allowed. Data were assessed until last visit, at data cut‐off, on or after September 1, 2019. Results A total of 240 patients meeting eligibility criteria were assessed (median [max] exposure 30.2 [43.0] months), with 177 patients continuing cenobamate at data cut‐off. Most common baseline concomitant ASMs were lacosamide, levetiracetam, lamotrigine, zonisamide, and clobazam. For most baseline concomitant ASMs, ~70% of patients taking that ASM were continuing cenobamate at data cut‐off. Patients continuing cenobamate had greater mean ASM dose reductions and percent dose changes from baseline vs those who discontinued. Of patients continuing cenobamate, 24.6% discontinued one or more concomitant ASMs completely. Dose decreases for all concomitant ASMs generally occurred during titration or early maintenance phases and were mostly due to central nervous system (CNS)–related adverse events such as somnolence, dizziness, unsteady gait, and fatigue. Responder rates from ≥50% through 100% for patients continuing cenobamate were generally similar regardless of concomitant ASMs (of those most commonly taken), with ~81% being ≥50% responders and ~12% achieving 100% seizure reduction in the maintenance phase, which lasted up to 40.2 (median = 29.5) months. Significance Concomitant ASM dose reductions were associated with more patients remaining on cenobamate. This is likely due to efficacy and improved tolerability, with overall reduced concomitant drug burden in patients with uncontrolled seizures despite taking one to three baseline concomitant ASMs.
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Affiliation(s)
- William E Rosenfeld
- Comprehensive Epilepsy Care Center for Children and Adults, St. Louis, Missouri, USA
| | | | | | | | - Victor Biton
- Arkansas Epilepsy Program, Little Rock, Arkansas, USA
| | - Gregory L Krauss
- Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | | | - David G Vossler
- University of Washington School of Medicine, Seattle, Washington, USA
| | - Pavel Klein
- Mid-Atlantic Epilepsy and Sleep Center, Bethesda, Maryland, USA
| | - Robert Wechsler
- Consultants in Epilepsy & Neurology, PLLC, Boise, Idaho, USA.,Idaho Comprehensive Epilepsy Center, Boise, Idaho, USA
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18
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Steinhoff BJ, Rosenfeld WE, Serratosa JM, Brandt C, Klein P, Toledo M, Krauss GL. Practical guidance for the management of adults receiving adjunctive cenobamate for the treatment of focal epilepsy-expert opinion. Epilepsy Behav 2021; 123:108270. [PMID: 34509033 DOI: 10.1016/j.yebeh.2021.108270] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/13/2021] [Accepted: 08/14/2021] [Indexed: 10/20/2022]
Abstract
Clinical trial results have demonstrated that adjunctive cenobamate (CNB) substantially decreases seizure frequency in adults with uncontrolled focal onset seizures with an acceptable and well-identified safety profile. This manuscript summarizes an expert panel's recommendations regarding optimized CNB treatment of epilepsies with focal onset seizures. Cenobamate, when slowly titrated to the target maintenance dose, represents an effective new antiseizure medication (ASM) with a comparatively high rate of seizure freedom relative to existing treatment options. This paper reviews selection of suitable CNB treatment candidates, realistic treatment expectations and goals, appropriate CNB target doses, and methods to mitigate or avoid potential adverse events. Cenobamate can be a promising therapeutic choice for adult people with epilepsy with focal onset seizures who do not reach adequate seizure control despite treatment with conventional ASMs.
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Affiliation(s)
- Bernhard J Steinhoff
- Department for Adults, Kork Epilepsy Center, Kehl-Kork, Germany; Clinic for Neurology and Neurophysiology, Freiburg, Germany.
| | - William E Rosenfeld
- Comprehensive Epilepsy Care Center for Children and Adults, St. Louis, MO, USA
| | - José M Serratosa
- Epilepsy Unit, Department of Neurology, Fundación Jiménez Díaz, Madrid, Spain
| | - Christian Brandt
- Department of General Epileptology, Bethel Epilepsy Centre, Mara Hospital, Bielefeld, Germany
| | - Pavel Klein
- Mid-Atlantic Epilepsy and Sleep Center, Bethesda, MD, USA
| | - Manuel Toledo
- Epilepsy Unit, Department of Neurology, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Gregory L Krauss
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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19
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Roberti R, De Caro C, Iannone LF, Zaccara G, Lattanzi S, Russo E. Pharmacology of Cenobamate: Mechanism of Action, Pharmacokinetics, Drug-Drug Interactions and Tolerability. CNS Drugs 2021; 35:609-618. [PMID: 33993416 DOI: 10.1007/s40263-021-00819-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/20/2021] [Indexed: 12/31/2022]
Abstract
Cenobamate is one of the latest antiseizure medications (ASMs) developed for the treatment of focal onset seizures in adult patients. The recommended starting dose is 12.5 mg/day, titrated gradually to the target daily dose of 200 mg, which may be increased to a maximum of 400 mg/day based on clinical response. Although the high rate of seizure freedom observed in randomized, placebo-controlled clinical trials has resulted in exciting expectations, further clinical studies are needed to better define its clinical profile. Cenobamate is characterized by a peculiar pharmacology regarding both pharmacodynamics and pharmacokinetics. The mechanism of action has only partly been described, with the drug acting on voltage-gated sodium channels through a pronounced action on persistent rather than transient currents. Cenobamate also acts as a positive allosteric modulator of GABAA receptors independently from the benzodiazepine binding site. The bioavailability of cenobamate is not influenced by other drugs, except phenytoin; it can inhibit cytochrome P450 (CYP) 2C19 and induce CYP3A4 and 2B6, and hence can potentially interact with many drugs (e.g. dose adjustments may be required for lamotrigine, carbamazepine and clobazam). The pharmacokinetics of cenobamate are not linear and dosage increases imply a disproportional increase in plasma levels, particularly at doses higher than 300 mg. The most common and dose-related adverse effects associated with cenobamate include central nervous system-related symptoms, mainly somnolence, dizziness, diplopia, and disturbances in gait and coordination. A somewhat higher incidence of adverse events has been observed in patients concomitantly treated with sodium channel blockers. The most relevant safety issues are currently represented by the risk of severe skin reactions (apparently avoidable by a slow titration) and QT shortening (the drug is contraindicated in patients with familial short QT syndrome or taking QT-shortening drugs). Overall, cenobamate is a promising ASM with an intriguing and not fully understood mechanism of action; pharmacokinetic issues need to be considered in clinical practice.
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Affiliation(s)
- Roberta Roberti
- Science of Health Department, University Magna Grecia of Catanzaro, Via T. Campanella, 115, 88100, Catanzaro, Italy
| | - Carmen De Caro
- Science of Health Department, University Magna Grecia of Catanzaro, Via T. Campanella, 115, 88100, Catanzaro, Italy
| | - Luigi Francesco Iannone
- Science of Health Department, University Magna Grecia of Catanzaro, Via T. Campanella, 115, 88100, Catanzaro, Italy
| | | | - Simona Lattanzi
- Neurological Clinic, Department of Experimental and Clinical Medicine, Marche Polytechnic University, Ancona, Italy
| | - Emilio Russo
- Science of Health Department, University Magna Grecia of Catanzaro, Via T. Campanella, 115, 88100, Catanzaro, Italy.
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Pagès N, Maurois P, Bac P, Meza-Toledo S, Peralta-Cruz J, Chamorro-Cevallos G, Cristóbal-Luna JM, Vamecq J. Anticonvulsive profile of two GABA B receptor antagonists on acute seizure mice models. Epilepsy Res 2021; 174:106644. [PMID: 33932748 DOI: 10.1016/j.eplepsyres.2021.106644] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 04/04/2021] [Accepted: 04/16/2021] [Indexed: 11/28/2022]
Abstract
INTRODUCTION DL-3-hydroxy-3-phenylpentanamide (HEPP) and DL-3-hydroxy-3-(4'chlorophenyl)-pentanamide (Cl-HEPP) are phenyl-alcohol-amides that are metabotropic GABAB receptor (MGBR) antagonists and protective against absence seizures. This study aims to further characterize the anticonvulsant profile of these drugs. METHODS HEPP and Cl-HEPP were evaluated in various standardized acute seizure and toxic tests in female Swiss-OF1 mice. RESULTS Toxicities of HEPP and Cl-HEPP were limited; doses up to 30 mg/kg did not result in hypothermia, reduced spontaneous locomotor activity, or failure of the rotarod test, with doses >15 mg/kg potentiating pentobarbital-induced sleep. In maximal electroshock-induced seizures, 20 mg/kg Cl-HEPP protected 100 % of mice; lower doses shortened post-ictal recovery. Seizure protection occurred against subcutaneous pentylenetetrazole and picrotoxin, being limited against N-methyl-d-aspartate. In bicuculline test, clonic or fatal tonic seizures were decreased, onset delayed, and recovery improved; ED50 values (dose protecting 50 % of the animals) were 37.5 and 25 mg/kg for HEPP and Cl-HEPP, respectively. In magnesium deficiency-dependent audiogenic seizures (MDDAS), ED50 values were 3 and 8 mg/kg for Cl-HEPP and HEPP, respectively. The components of MDDAS (latency, wild running, seizure, and recovery phases) in unprotected animals were only minimally affected by near ED50 doses of Cl-HEPP and HEPP. DISCUSSION HEPP and, to a greater extent, Cl-HEPP provide anti-seizure protections in several acute seizure tests in mice at nontoxic doses. These results are consistent with the action of these drugs on diverse molecular targets directly resulting from their MGBR antagonistic properties. However, other mechanisms might occur possibly for the protection given in the MES test. Finally, a similarity in the modulation of MDDAS components between the two phenyl alcohol amides and ethosuximide could also be based on the MGBR antagonistic properties of the former, given the recently re-evaluated therapeutic relevant targets of the latter.
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Affiliation(s)
- Nicole Pagès
- Toxicology Laboratory, Faculty of Pharmacy, 67400 Illkirch, France; Neuropharmacology Laboratory, Faculty of Pharmacy, 92290 Châtenay Malabry, France
| | - Pierre Maurois
- Neuropharmacology Laboratory, Faculty of Pharmacy, 92290 Châtenay Malabry, France
| | - Pierre Bac
- Neuropharmacology Laboratory, Faculty of Pharmacy, 92290 Châtenay Malabry, France
| | - Sergio Meza-Toledo
- Departamento de Bioquímica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional (IPN), Ciudad de México, Mexico
| | - Javier Peralta-Cruz
- Departamento de Química Orgánica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional (IPN), Ciudad de México, Mexico
| | - Germán Chamorro-Cevallos
- Departamento de Farmacia, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional (IPN), Ciudad de México, Mexico
| | - José Melesio Cristóbal-Luna
- Departamento de Farmacia, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional (IPN), Ciudad de México, Mexico
| | - Joseph Vamecq
- Inserm, Biochemistry and Molecular Biology Laboratory, HMNO, CBP, CHRU Lille & EA 7364 - RADEME, North France University Lille, 2, Bld Prof Jules Leclercq, 59037, Lille, France.
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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.
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22
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Földi MC, Pesti K, Zboray K, Toth AV, Hegedűs T, Málnási-Csizmadia A, Lukacs P, Mike A. The mechanism of non-blocking inhibition of sodium channels revealed by conformation-selective photolabeling. Br J Pharmacol 2021; 178:1200-1217. [PMID: 33450052 DOI: 10.1111/bph.15365] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 12/10/2020] [Accepted: 01/03/2021] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Sodium channel inhibitors can be used to treat hyperexcitability-related diseases, including epilepsies, pain syndromes, neuromuscular disorders and cardiac arrhythmias. The applicability of these drugs is limited by their nonspecific effect on physiological function. They act mainly by sodium channel block and in addition by modulation of channel kinetics. While channel block inhibits healthy and pathological tissue equally, modulation can preferentially inhibit pathological activity. An ideal drug designed to target the sodium channels of pathological tissue would act predominantly by modulation. Thus far, no such drug has been described. EXPERIMENTAL APPROACH Patch-clamp experiments with ultra-fast solution exchange and photolabeling-coupled electrophysiology were applied to describe the unique mechanism of riluzole on Nav1.4 sodium channels. In silico docking experiments were used to study the molecular details of binding. KEY RESULTS We present evidence that riluzole acts predominantly by non-blocking modulation. We propose that, being a relatively small molecule, riluzole is able to stay bound to the binding site, but nonetheless stay off the conduction pathway, by residing in one of the fenestrations. We demonstrate how this mechanism can be recognized. CONCLUSIONS AND IMPLICATIONS Our results identify riluzole as the prototype of this new class of sodium channel inhibitors. Drugs of this class are expected to selectively prevent hyperexcitability, while having minimal effect on cells firing at a normal rate from a normal resting potential.
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Affiliation(s)
- Mátyás C Földi
- MTA-ELTE NAP B Opto-Neuropharmacology Group, Budapest, Hungary.,Plant Protection Institute, Centre for Agricultural Research, Martonvásár, Hungary
| | - Krisztina Pesti
- MTA-ELTE NAP B Opto-Neuropharmacology Group, Budapest, Hungary.,Department of Biochemistry, Eötvös Loránd University, Budapest, Hungary.,School of PhD Studies, Semmelweis University, Budapest, Hungary
| | - Katalin Zboray
- Plant Protection Institute, Centre for Agricultural Research, Martonvásár, Hungary
| | - Adam V Toth
- Plant Protection Institute, Centre for Agricultural Research, Martonvásár, Hungary
| | - Tamás Hegedűs
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - András Málnási-Csizmadia
- Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Budapest, Hungary
| | - Peter Lukacs
- MTA-ELTE NAP B Opto-Neuropharmacology Group, Budapest, Hungary.,Plant Protection Institute, Centre for Agricultural Research, Martonvásár, Hungary
| | - Arpad Mike
- MTA-ELTE NAP B Opto-Neuropharmacology Group, Budapest, Hungary.,Plant Protection Institute, Centre for Agricultural Research, Martonvásár, Hungary.,Department of Biochemistry, Eötvös Loránd University, Budapest, Hungary
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23
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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.
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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
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24
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Inhibitory Effectiveness of Gomisin A, a Dibenzocyclooctadiene Lignan Isolated from Schizandra chinensis, on the Amplitude and Gating of Voltage-Gated Na + Current. Int J Mol Sci 2020; 21:ijms21228816. [PMID: 33233411 PMCID: PMC7700137 DOI: 10.3390/ijms21228816] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 11/18/2020] [Accepted: 11/19/2020] [Indexed: 12/12/2022] Open
Abstract
Gomisin A (Gom A), a lignan isolated from Schisandra chinensis, has been reported produce numerous biological activities. However, its action on the ionic mechanisms remains largely unanswered. The present experiments were undertaken to investigate the possible perturbations of Gom A or other related compounds on different types of membrane ionic currents in electrically excitable cells (i.e., pituitary GH3 and pancreatic INS-1 cells). The exposure to Gom A led to the differential inhibition of peak and end-pulse components of voltage-gated Na+ current (INa) in GH3 cells with effective IC50 of 6.2 and 0.73 μM, respectively. The steady-state inactivation curve of INa in the presence of Gom A was shifted towards a more hyperpolarized potential. However, neither changes in the overall current-voltage relationship nor those for the gating charge of the current were demonstrated. The application of neither morin (10 μM) nor hesperidin (10 μM) perturbed the strength of INa, while sesamine could suppress it. However, in the continued presence of Gom A, the addition of sesamine failed to suppress INa further. Gom A also effectively suppressed the strength of persistent INa activated by long ramp voltage command, and further application of tefluthrin effectively attenuated Gom A-mediated inhibition of the current. The presence of Gom A mildly inhibited erg-mediated K+ current, while a lack of change in the amplitude of hyperpolarization-activated cation current was observed in its presence. Under cell-attached current recordings, the exposure to Gom A resulted in the decreased firing of spontaneous action currents with a minimal change in AC amplitude. In pancreatic INS-1 cells, the presence of Gom A was also noticed to inhibit peak and end-pulse components of INa differentially with the IC50 of 5.9 and 0.84 μM, respectively. Taken together, the emerging results presented herein provide the evidence that Gom A can differentially inhibit peak and sustained INa in endocrine cells (e.g., GH3 and INS-1 cells).
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25
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Shore AN, Colombo S, Tobin WF, Petri S, Cullen ER, Dominguez S, Bostick CD, Beaumont MA, Williams D, Khodagholy D, Yang M, Lutz CM, Peng Y, Gelinas JN, Goldstein DB, Boland MJ, Frankel WN, Weston MC. Reduced GABAergic Neuron Excitability, Altered Synaptic Connectivity, and Seizures in a KCNT1 Gain-of-Function Mouse Model of Childhood Epilepsy. Cell Rep 2020; 33:108303. [PMID: 33113364 PMCID: PMC7712469 DOI: 10.1016/j.celrep.2020.108303] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 08/06/2020] [Accepted: 10/01/2020] [Indexed: 01/07/2023] Open
Abstract
Gain-of-function (GOF) variants in K+ channels cause severe childhood epilepsies, but there are no mechanisms to explain how increased K+ currents lead to network hyperexcitability. Here, we introduce a human Na+-activated K+ (KNa) channel variant (KCNT1-Y796H) into mice and, using a multiplatform approach, find motor cortex hyperexcitability and early-onset seizures, phenotypes strikingly similar to those of human patients. Although the variant increases KNa currents in cortical excitatory and inhibitory neurons, there is an increase in the KNa current across subthreshold voltages only in inhibitory neurons, particularly in those with non-fast-spiking properties, resulting in inhibitory-neuron-specific impairments in excitability and action potential (AP) generation. We further observe evidence of synaptic rewiring, including increases in homotypic synaptic connectivity, accompanied by network hyperexcitability and hypersynchronicity. These findings support inhibitory-neuron-specific mechanisms in mediating the epileptogenic effects of KCNT1 channel GOF, offering cell-type-specific currents and effects as promising targets for therapeutic intervention.
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Affiliation(s)
- Amy N Shore
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA
| | - Sophie Colombo
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | - William F Tobin
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA
| | - Sabrina Petri
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | - Erin R Cullen
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA
| | - Soledad Dominguez
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | | | - Michael A Beaumont
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Axion BioSystems, Atlanta, GA 30309, USA
| | - Damian Williams
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | - Dion Khodagholy
- Department of Electrical Engineering, Columbia University, New York, NY 10032, USA
| | - Mu Yang
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | | | - Yueqing Peng
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Jennifer N Gelinas
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Neurology, Columbia University, New York, NY 10032, USA
| | - David B Goldstein
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Genetics and Development, Columbia University, New York, NY 10032, USA
| | - Michael J Boland
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Genetics and Development, Columbia University, New York, NY 10032, USA
| | - Wayne N Frankel
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Neurology, Columbia University, New York, NY 10032, USA
| | - Matthew C Weston
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA.
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26
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Guignet M, Campbell A, White HS. Cenobamate (XCOPRI): Can preclinical and clinical evidence provide insight into its mechanism of action? Epilepsia 2020; 61:2329-2339. [DOI: 10.1111/epi.16718] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/11/2020] [Accepted: 09/16/2020] [Indexed: 12/31/2022]
Affiliation(s)
- Michelle Guignet
- Department of Pharmacy School of Pharmacy University of Washington Seattle WA USA
| | - Amanda Campbell
- Department of Pharmacy School of Pharmacy University of Washington Seattle WA USA
| | - H. Steve White
- Department of Pharmacy School of Pharmacy University of Washington Seattle WA USA
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27
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Comelli M, Meo M, Cervantes DO, Pizzo E, Plosker A, Mohler PJ, Hund TJ, Jacobson JT, Meste O, Rota M. Rhythm dynamics of the aging heart: an experimental study using conscious, restrained mice. Am J Physiol Heart Circ Physiol 2020; 319:H893-H905. [PMID: 32886003 DOI: 10.1152/ajpheart.00379.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Heart rate variability (HRV) is a measure of variation in time interval between heartbeats and reflects the influence of autonomic nervous system and circulating/locally released factors on sinoatrial node discharge. Here, we tested whether electrocardiograms (ECGs) obtained in conscious, restrained mice, a condition that affects sympathovagal balance, reveal alterations of heart rhythm dynamics with aging. Moreover, based on emergence of sodium channels as modulators of pacemaker activity, we addressed consequences of altered sodium channels on heart rhythm. C57Bl/6 mice and mice with enhanced late sodium current due to Nav1.5 mutation at Ser571 (S571E) at ~4 to ~24 mo of age, were studied. HRV was assessed using time- and frequency-domain and nonlinear parameters. For C57Bl/6 and S571E mice, standard deviation of RR intervals (SDRR), total power of RR interval variation, and nonlinear standard deviation 2 (SD2) were maximal at ~4 mo and decreased at ~18 and ~24 mo, together with attenuation of indexes of sympathovagal balance. Modulation of sympathetic and/or parasympathetic divisions revealed attenuation of autonomic tone at ~24 mo. At ~4 mo, S571E mice presented lower heart rate and higher SDRR, total power, and SD2 with respect to C57Bl/6, properties reversed by late sodium current inhibition. At ~24 mo, heart rate decreased in C57Bl/6 but increased in S571E, a condition preserved after autonomic blockade. Collectively, our data indicate that aging is associated with reduced HRV. Moreover, sodium channel function conditions heart rate and its age-related adaptations, but does not interfere with HRV decline occurring with age.NEW & NOTEWORTHY We have investigated age-associated alterations of heart rate properties in mice using conscious electrocardiographic recordings. Our findings support the notion that aging is coupled with altered sympathovagal balance with consequences on heart rate variability. Moreover, by using a genetically engineered mouse line, we provide evidence that sodium channels modulate heart rate and its age-related adaptations.
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Affiliation(s)
- Martina Comelli
- Department of Physiology, New York Medical College, Valhalla, New York
| | - Marianna Meo
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Bordeaux University Foundation, F-33600 Pessac-Bordeaux, France, with Univ. Bordeaux and INSERM, CRCTB, U1045, Bordeaux, France
| | | | - Emanuele Pizzo
- Department of Physiology, New York Medical College, Valhalla, New York
| | - Aaron Plosker
- Department of Physiology, New York Medical College, Valhalla, New York
| | - Peter J Mohler
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio.,Department of Physiology and Cell Biology, The Ohio State University College of Medicine, Columbus, Ohio.,Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, Ohio
| | - Thomas J Hund
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio.,Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, Ohio.,Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio
| | - Jason T Jacobson
- Department of Physiology, New York Medical College, Valhalla, New York.,Division of Cardiology, Department of Medicine, Westchester Medical Center, New York Medical College, Valhalla, New York
| | - Olivier Meste
- Laboratoire d'Informatique, Signaux et Systèmes de Sophia Antipolis, Université Côte d'Azur, CNRS, I3S, France
| | - Marcello Rota
- Department of Physiology, New York Medical College, Valhalla, New York
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28
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Lai MC, Wu SN, Huang CW. Telmisartan, an Antagonist of Angiotensin II Receptors, Accentuates Voltage-Gated Na + Currents and Hippocampal Neuronal Excitability. Front Neurosci 2020; 14:902. [PMID: 33013297 PMCID: PMC7499822 DOI: 10.3389/fnins.2020.00902] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Accepted: 08/03/2020] [Indexed: 12/19/2022] Open
Abstract
Telmisartan (TEL), a non-peptide blocker of the angiotensin II type 1 receptor, is a widely used antihypertensive agent. Nevertheless, its neuronal ionic effects and how they potentially affect neuronal network excitability remain largely unclear. With the aid of patch-clamp technology, the effects of TEL on membrane ion currents present in hippocampal neurons (mHippoE-14 cells) were investigated. For additional characterization of the effects of TEL on hippocampal neuronal excitability, we undertook in vivo studies on Sprague Dawley (SD) rats using pilocarpine-induced seizure modeling, a hippocampal histopathological analysis, and inhibitory avoidance testing. In these hippocampal neurons, TEL increased the peak amplitude of INa, with a concomitant decline in the current inactivation rate. The TEL concentration dependently enhanced the peak amplitude of depolarization-elicited INa and lessened the inactivation rate of INa. By comparison, TEL was more efficacious in stimulating the peak INa and in prolonging the inactivation time course of this current than tefluthrin or (-)-epicatechin-3-gallate. In the continued presence of pioglitazone, the TEL-perturbed stimulation of INa remained effective. In addition, cell exposure to TEL shifted the steady-state inactivation INa curve to fewer negative potentials with no perturbations of the slope factor. Unlike chlorotoxin, either ranolazine, eugenol, or KMUP-1 reversed TEL-mediated increases in the strength of non-inactivating INa. In the cell-attached voltage-clamp recordings, TEL shortened the latency in the generation of action currents. Meanwhile, TEL increased the peak INa, with a concurrent decrease in current inactivation in HEKT293T cells expressing SCN5A. Furthermore, although TEL did not aggravate pilocarpine-induced chronic seizures and tended to preserve cognitive performance, it significantly accentuated hippocampal mossy fiber sprouting. Collectively, TEL stimulation of peak INa in combination with an apparent retardation in current inactivation could be an important mechanism through which hippocampal neuronal excitability is increased, and hippocampal network excitability is accentuated following status epilepticus, suggesting further attention to this finding.
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Affiliation(s)
- Ming-Chi Lai
- Department of Pediatrics, Chi-Mei Medical Center, Tainan, Taiwan
| | - Sheng-Nan Wu
- Department of Physiology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chin-Wei Huang
- Department of Neurology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
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29
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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.
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Affiliation(s)
- Miriam H Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan
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30
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Auvin S, Avbersek A, Bast T, Chiron C, Guerrini R, Kaminski RM, Lagae L, Muglia P, Cross JH. Drug Development for Rare Paediatric Epilepsies: Current State and Future Directions. Drugs 2020; 79:1917-1935. [PMID: 31734883 DOI: 10.1007/s40265-019-01223-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Rare diseases provide a challenge in the evaluation of new therapies. However, orphan drug development is of increasing interest because of the legislation enabling facilitated support by regulatory agencies through scientific advice, and the protection of the molecules with orphan designation. In the landscape of the rare epilepsies, very few syndromes, namely Dravet syndrome, Lennox-Gastaut syndrome and West syndrome, have been subject to orphan drug development. Despite orphan designations for rare epilepsies having dramatically increased in the past 10 years, the number of approved drugs remains limited and restricted to a handful of epilepsy syndromes. In this paper, we describe the current state of orphan drug development for rare epilepsies. We identified a large number of compounds currently under investigation, but mostly in the same rare epilepsy syndromes as in the past. A rationale for further development in rare epilepsies could be based on the match between the drug mechanisms of action and the knowledge of the causative gene mutation or by evidence from animal models. In case of the absence of strong pathophysiological hypotheses, exploratory/basket clinical studies could be helpful to identify a subpopulation that may benefit from the new drug. We provide some suggestions for future improvements in orphan drug development such as promoting paediatric drug investigations, better evaluation of the incidence and the prevalence, together with the natural history data, and the development of new primary outcomes.
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Affiliation(s)
- Stéphane Auvin
- PROTECT, INSERM U1141, Université de Paris, Paris, France. .,Service de Neurologie Pédiatrique, AP-HP, Hôpital Universitaire Robert-Debré, 48, Boulevard Sérurier, 75935, Paris Cedex 19, France.
| | | | - Thomas Bast
- The Kork Epilepsy Center, Kehl-Kork, Germany.,Medical Faculty of the University of Freiburg, Freiburg, Germany
| | - Catherine Chiron
- PROTECT, INSERM U1141, Université de Paris, Paris, France.,Service de Neurologie Pédiatrique, AP-HP, Hôpital Necker-Enfanst Malades, Paris, France
| | - Renzo Guerrini
- Neuroscience Department, Children's Hospital Anna Meyer-University of Florence, Florence, Italy
| | - Rafal M Kaminski
- UCB Pharma, Braine-l'Alleud, Belgium.,Roche Pharma Research and Early Development (pRED), Roche Innovation Center, Basel, Switzerland
| | - Lieven Lagae
- Department Development and Regeneration, Section Paediatric Neurology, University Hospitals, University of Leuven, Leuven, Belgium
| | | | - J Helen Cross
- UCL NIHR BRC Great Ormond Street Institute of Child Health, London, UK
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31
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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.
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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;
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32
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Interneuron Desynchronization Precedes Seizures in a Mouse Model of Dravet Syndrome. J Neurosci 2020; 40:2764-2775. [PMID: 32102923 DOI: 10.1523/jneurosci.2370-19.2020] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 12/27/2019] [Accepted: 02/13/2020] [Indexed: 12/14/2022] Open
Abstract
Recurrent seizures, which define epilepsy, are transient abnormalities in the electrical activity of the brain. The mechanistic basis of seizure initiation, and the contribution of defined neuronal subtypes to seizure pathophysiology, remains poorly understood. We performed in vivo two-photon calcium imaging in neocortex during temperature-induced seizures in male and female Dravet syndrome (Scn1a+/-) mice, a neurodevelopmental disorder with prominent temperature-sensitive epilepsy. Mean activity of both putative principal cells and parvalbumin-positive interneurons (PV-INs) was higher in Scn1a+/- relative to wild-type controls during quiet wakefulness at baseline and at elevated core body temperature. However, wild-type PV-INs showed a progressive synchronization in response to temperature elevation that was absent in PV-INs from Scn1a+/- mice. Hence, PV-IN activity remains intact interictally in Scn1a+/- mice, yet exhibits decreased synchrony immediately before seizure onset. We suggest that impaired PV-IN synchronization may contribute to the transition to the ictal state during temperature-induced seizures in Dravet syndrome.SIGNIFICANCE STATEMENT Epilepsy is a common neurological disorder defined by recurrent, unprovoked seizures. However, basic mechanisms of seizure initiation and propagation remain poorly understood. We performed in vivo two-photon calcium imaging in an experimental model of Dravet syndrome (Scn1a+/- mice)-a severe neurodevelopmental disorder defined by temperature-sensitive, treatment-resistant epilepsy-and record activity of putative excitatory neurons and parvalbumin-positive GABAergic neocortical interneurons (PV-INs) during naturalistic seizures induced by increased core body temperature. PV-IN activity was higher in Scn1a+/- relative to wild-type controls during quiet wakefulness. However, wild-type PV-INs showed progressive synchronization in response to temperature elevation that was absent in PV-INs from Scn1a+/- mice before seizure onset. Hence, impaired PV-IN synchronization may contribute to transition to seizure in Dravet syndrome.
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33
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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.
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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.
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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.
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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.
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The Novel Direct Modulatory Effects of Perampanel, an Antagonist of AMPA Receptors, on Voltage-Gated Sodium and M-type Potassium Currents. Biomolecules 2019; 9:biom9100638. [PMID: 31652643 PMCID: PMC6843791 DOI: 10.3390/biom9100638] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 10/20/2019] [Indexed: 12/17/2022] Open
Abstract
Perampanel (PER) is a selective blocker of AMPA receptors showing efficacy in treating various epileptic disorders including brain tumor-related epilepsy and also potential in treating motor neuron disease. However, besides its inhibition of AMPA-induced currents, whether PER has any other direct ionic effects in different types of neurons remains largely unknown. We investigated the effects of PER and related compounds on ionic currents in different types of cells, including hippocampal mHippoE-14 neurons, motor neuron-like NSC-34 cells and U87 glioma cells. We found that PER differentially and effectively suppressed the amplitude of voltage-gated Na+ currents (INa) in mHippoE-14 cells. The IC50 values required to inhibit peak and late INa were 4.12 and 0.78 μM, respectively. PER attenuated tefluthrin-induced increases in both amplitude and deactivating time constant of INa. Importantly, PER also inhibited the amplitude of M-type K+ currents (IK(M)) with an IC50 value of 0.92 μM. The suppression of IK(M) was attenuated by the addition of flupirtine or ZnCl2 but not by L-quisqualic acid or sorafenib. Meanwhile, in cell-attached configuration, PER (3 μM) decreased the activity of M-type K+ channels with no change in single-channel conductance but shifting the activation curve along the voltage axis in a rightward direction. Supportively, PER suppressed IK(M) in NSC-34 cells and INa in U87 glioma cells. The inhibitory effects of PER on both INa and IK(M), independent of its antagonistic effect on AMPA receptors, may be responsible for its wide-spectrum of effects observed in neurological clinical practice.
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36
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Kang YJ, Clement EM, Sumsky SL, Xiang Y, Park IH, Santaniello S, Greenfield LJ, Garcia-Rill E, Smith BN, Lee SH. The critical role of persistent sodium current in hippocampal gamma oscillations. Neuropharmacology 2019; 162:107787. [PMID: 31550457 DOI: 10.1016/j.neuropharm.2019.107787] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Revised: 09/11/2019] [Accepted: 09/19/2019] [Indexed: 10/25/2022]
Abstract
Gamma network oscillations in the brain are fast rhythmic network oscillations in the gamma frequency range (~30-100 Hz), playing key roles in the hippocampus for learning, memory, and spatial processing. There is evidence indicating that GABAergic interneurons, including parvalbumin-expressing basket cells (PVBCs), contribute to cortical gamma oscillations through synaptic interactions with excitatory cells. However, the molecular, cellular, and circuit underpinnings underlying generation and maintenance of cortical gamma oscillations are largely elusive. Recent studies demonstrated that intrinsic and synaptic properties of GABAergic interneurons and excitatory cells are regulated by a slowly inactivating or non-inactivating sodium current (i.e., persistent sodium current, INaP), suggesting that INaP is involved in gamma oscillations. Here, we tested whether INaP plays a role in hippocampal gamma oscillations using pharmacological, optogenetic, and electrophysiological approaches. We found that INaP blockers, phenytoin (40 μM and 100 μM) and riluzole (10 μM), reduced gamma oscillations induced by optogenetic stimulation of CaMKII-expressing cells in CA1 networks. Whole-cell patch-clamp recordings further demonstrated that phenytoin (100 μM) reduced INaP and firing frequencies in both PVBCs and pyramidal cells without altering threshold and amplitude of action potentials, but increased rheobase in both cell types. These results suggest that INaP in pyramidal cells and PVBCs is required for hippocampal gamma oscillations, supporting a pyramidal-interneuron network gamma model. Phenytoin-mediated modulation of hippocampal gamma oscillations may be a mechanism underlying its anticonvulsant efficacy, as well as its contribution to cognitive impairments in epilepsy patients.
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Affiliation(s)
- Young-Jin Kang
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; Department of Neuroscience, University of Kentucky, Lexington, KY 40536, USA
| | - Ethan M Clement
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Stefan L Sumsky
- Biomedical Engineering Department, CT Institute for Brain and Cognitive Sciences, University of Connecticut, Storrs, CT 06269, USA
| | - Yangfei Xiang
- Department of Genetics, Yale Stem Cell Center, Yale Child Study Center, Yale School of Medicine, New Haven, CT 06520, USA
| | - In-Hyun Park
- Department of Genetics, Yale Stem Cell Center, Yale Child Study Center, Yale School of Medicine, New Haven, CT 06520, USA
| | - Sabato Santaniello
- Biomedical Engineering Department, CT Institute for Brain and Cognitive Sciences, University of Connecticut, Storrs, CT 06269, USA
| | - Lazar John Greenfield
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; Department of Neurology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Edgar Garcia-Rill
- Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Bret N Smith
- Department of Neuroscience, University of Kentucky, Lexington, KY 40536, USA
| | - Sang-Hun Lee
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; Department of Neuroscience, University of Kentucky, Lexington, KY 40536, USA; Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
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37
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Bunton-Stasyshyn RKA, Wagnon JL, Wengert ER, Barker BS, Faulkner A, Wagley PK, Bhatia K, Jones JM, Maniaci MR, Parent JM, Goodkin HP, Patel MK, Meisler MH. Prominent role of forebrain excitatory neurons in SCN8A encephalopathy. Brain 2019; 142:362-375. [PMID: 30601941 DOI: 10.1093/brain/awy324] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 10/29/2018] [Indexed: 12/25/2022] Open
Abstract
De novo mutations of the sodium channel gene SCN8A result in an epileptic encephalopathy with refractory seizures, developmental delay, and elevated risk of sudden death. p.Arg1872Trp is a recurrent de novo SCN8A mutation reported in 14 unrelated individuals with epileptic encephalopathy that included seizure onset in the prenatal or infantile period and severe verbal and ambulatory comorbidities. The major biophysical effect of the mutation was previously shown to be impaired channel inactivation accompanied by increased current density. We have generated a conditional mouse mutation in which expression of this severe gain-of-function mutation is dependent upon Cre recombinase. Global activation of p.Arg1872Trp by EIIa-Cre resulted in convulsive seizures and lethality at 2 weeks of age. Neural activation of the p.Arg1872Trp mutation by Nestin-Cre also resulted in early onset seizures and death. Restriction of p.Arg1872Trp expression to excitatory neurons using Emx1-Cre recapitulated seizures and juvenile lethality between 1 and 2 months of age. In contrast, activation of p.Arg1872Trp in inhibitory neurons by Gad2-Cre or Dlx5/6-Cre did not induce seizures or overt neurological dysfunction. The sodium channel modulator GS967/Prax330 prolonged survival of mice with global expression of R1872W and also modulated the activity of the mutant channel in transfected cells. Activation of the p.Arg1872Trp mutation in adult mice was sufficient to generate seizures and death, indicating that successful therapy will require lifelong treatment. These findings provide insight into the pathogenic mechanism of this gain-of-function mutation of SCN8A and identify excitatory neurons as critical targets for therapeutic intervention.
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Affiliation(s)
| | - Jacy L Wagnon
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Eric R Wengert
- Department of Anesthesiology, University of Virginia, Charlottesville VA, USA.,Neuroscience Graduate Program, University of Virginia, Charlottesville VA, USA
| | - Bryan S Barker
- Department of Anesthesiology, University of Virginia, Charlottesville VA, USA.,Neuroscience Graduate Program, University of Virginia, Charlottesville VA, USA
| | - Alexa Faulkner
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA
| | - Pravin K Wagley
- Department of Neurology, University of Virginia, Charlottesville VA, USA
| | - Kritika Bhatia
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Julie M Jones
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Marissa R Maniaci
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Jack M Parent
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA.,Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Howard P Goodkin
- Neuroscience Graduate Program, University of Virginia, Charlottesville VA, USA.,Department of Neurology, University of Virginia, Charlottesville VA, USA
| | - Manoj K Patel
- Department of Anesthesiology, University of Virginia, Charlottesville VA, USA.,Neuroscience Graduate Program, University of Virginia, Charlottesville VA, USA
| | - Miriam H Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA.,Department of Neurology, University of Michigan, Ann Arbor, MI, USA
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Zaman T, Abou Tayoun A, Goldberg EM. A single-center SCN8A-related epilepsy cohort: clinical, genetic, and physiologic characterization. Ann Clin Transl Neurol 2019; 6:1445-1455. [PMID: 31402610 PMCID: PMC6689675 DOI: 10.1002/acn3.50839] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 06/20/2019] [Accepted: 06/21/2019] [Indexed: 12/13/2022] Open
Abstract
Objective Pathogenic variants in SCN8A, encoding the voltage‐gated sodium (Na+) channel α subunit Nav1.6, is a known cause of epilepsy. Here, we describe clinical and genetic features of all patients with SCN8A epilepsy evaluated at a single‐tertiary care center, with biophysical data on identified Nav1.6 variants and pharmacological response to selected Na+ channel blockers. Methods SCN8A variants were identified via an exome‐based panel of epilepsy‐associated genes for next generation sequencing (NGS), or via exome sequencing. Biophysical characterization was performed using voltage‐clamp recordings of ionic currents in heterologous cells. Results We observed a range in age of onset and severity of epilepsy and associated developmental delay/intellectual disability. Na+ channel blockers were highly or partially effective in most patients. Nav1.6 variants exhibited one or more biophysical defects largely consistent with gain of channel function. We found that clinical severity was correlated with the presence of multiple observed biophysical defects and the extent to which pathological Na+ channel activity could be normalized pharmacologically. For variants not previously reported, functional studies enhanced the evidence of pathogenicity. Interpretation We present a comprehensive single‐center dataset for SCN8A epilepsy that includes clinical, genetic, electrophysiologic, and pharmacologic data. We confirm a spectrum of severity and a variety of biophysical defects of Nav1.6 variants consistent with gain of channel function. Na+ channel blockers in the treatment of SCN8A epilepsy may correlate with the effect of such agents on pathological Na+ current observed in heterologous systems.
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Affiliation(s)
- Tariq Zaman
- Division of Neurology Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104
| | - Ahmad Abou Tayoun
- Division of Genomic Diagnostics, Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104.,Genetics Department, Al Jalila Children's Specialty Hospital, Dubai, United Arab Emirates
| | - Ethan M Goldberg
- Division of Neurology Department of Pathology, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104.,Department of Neurology, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19104.,Department of Neuroscience, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19104.,The Epilepsy Neurogenetics Initiative, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104
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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'.
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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
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40
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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.
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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.
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Nakamura M, Cho JH, Shin H, Jang IS. Effects of cenobamate (YKP3089), a newly developed anti-epileptic drug, on voltage-gated sodium channels in rat hippocampal CA3 neurons. Eur J Pharmacol 2019; 855:175-182. [PMID: 31063770 DOI: 10.1016/j.ejphar.2019.05.007] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 04/30/2019] [Accepted: 05/03/2019] [Indexed: 11/26/2022]
Abstract
New, more effective pharmacologic treatments for epilepsy are needed, as a substantial portion of patients (>30%) are refractory to currently available anti-epileptic drugs. Cenobamate (YKP3089) is an investigational anti-epileptic drug in clinical development. Two completed adequate and well-controlled studies demonstrated a significant reduction in focal seizures with cenobamate in patients with epilepsy. In this study, we characterized the effects of cenobamate on voltage-gated Na+ channels in acutely isolated rat hippocampal CA3 neurons using a whole-cell patch-clamp technique. While cenobamate had little effect on the peak component of transient Na+ current (INaT) induced by brief depolarizing step pulses, it potently inhibited the non-inactivating persistent component of INa (INaP). In addition, cenobamate potently inhibited the current by slow voltage-ramp stimuli. Cenobamate significantly shifted the steady-state fast inactivation relationship toward a hyperpolarizing range, indicating that cenobamate binds to voltage-gated Na+ channels at the inactivated state with a higher affinity. Cenobamate also accelerated the development of inactivation and retarded recovery from inactivation of voltage-gated Na+ channels. In current clamp experiments, cenobamate hyperpolarized membrane potentials in a concentration-dependent manner, and these effects were mediated by inhibiting the INaP. Cenobamate also increased the threshold for generation of action potentials, and decreased the number of action potentials elicited by depolarizing current injection. Given that the INaP plays a pivotal role in the repetitive and/or burst generation of action potentials, the cenobamate-mediated preferential blockade of INaP might contribute to anti-epileptic activity.
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Affiliation(s)
- Michiko Nakamura
- Department of Pharmacology, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 700-412, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 700-412, Republic of Korea.
| | - Jin-Hwa Cho
- Department of Pharmacology, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 700-412, Republic of Korea.
| | - Hyewon Shin
- Department of Pharmacology, SK Biopharmaceuticals, Co., Ltd., 221 Pangyoyeok-ro, Seongnam, Gyeonggi, 305-712, Republic of Korea.
| | - Il-Sung Jang
- Department of Pharmacology, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 700-412, Republic of Korea; Brain Science & Engineering Institute, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 700-412, Republic of Korea.
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Aiba I, Noebels JL. Adrenergic agonist induces rhythmic firing in quiescent cardiac preganglionic neurons in nucleus ambiguous via activation of intrinsic membrane excitability. J Neurophysiol 2019; 121:1266-1278. [PMID: 30699052 PMCID: PMC6485744 DOI: 10.1152/jn.00761.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Cholinergic vagal nerves projecting from neurons in the brain stem nucleus ambiguus (NAm) play a predominant role in cardiac parasympathetic pacemaking control. Central adrenergic signaling modulates the tone of this vagal output; however, the exact excitability mechanisms are not fully understood. We investigated responses of NAm neurons to adrenergic agonists using in vitro mouse brain stem slices. Preganglionic NAm neurons were identified by ChAT-tdTomato fluorescence in young adult transgenic mice, and their cardiac projection was confirmed by retrograde dye tracing. Juxtacellular recordings detected sparse or absent spontaneous action potentials (AP) in NAm neurons. However, bath application of epinephrine or norepinephrine strongly and reversibly activated most NAm neurons regardless of their basal firing rate. Epinephrine was more potent than norepinephrine, and this activation largely depends on α1-adrenoceptors. Interestingly, adrenergic activation of NAm neurons does not require an ionotropic synaptic mechanism, because postsynaptic excitatory or inhibitory receptor blockade did not occlude the excitatory effect, and bath-applied adrenergic agonists did not alter excitatory or inhibitory synaptic transmission. Instead, adrenergic agonists significantly elevated intrinsic membrane excitability to facilitate generation of recurrent action potentials. T-type calcium current and hyperpolarization-activated current are involved in this excitation pattern, although not required for spontaneous AP induction by epinephrine. In contrast, pharmacological blockade of persistent sodium current significantly inhibited the adrenergic effects. Our results demonstrate that central adrenergic signaling enhances the intrinsic excitability of NAm neurons and that persistent sodium current is required for this effect. This central balancing mechanism may counteract excessive peripheral cardiac excitation during increased sympathetic tone. NEW & NOTEWORTHY Cardiac preganglionic cholinergic neurons in the nucleus ambiguus (NAm) are responsible for slowing cardiac pacemaking. This study identified that adrenergic agonists can induce rhythmic action potentials in otherwise quiescent cholinergic NAm preganglionic neurons in brain stem slice preparation. The modulatory influence of adrenaline on central parasympathetic outflow may contribute to both physiological and deleterious cardiovascular regulation.
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Affiliation(s)
- Isamu Aiba
- Department of Neurology, Baylor College of Medicine , Houston, Texas
| | - Jeffrey L Noebels
- Department of Neurology, Baylor College of Medicine , Houston, Texas
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Abstract
Evidence from both preclinical and clinical studies suggest the importance of zinc homeostasis in seizures/epilepsy. Undoubtedly, zinc, via modulation of a variety of targets, is necessary for maintaining the balance between neuronal excitation and inhibition, while an imbalance between excitation and inhibition underlies seizures. However, the relationship between zinc signaling and seizures/epilepsy is complex as both extracellular and intracellular zinc may produce either protective or detrimental effects. This review provides an overview of preclinical/behavioral, functional and molecular studies, as well as clinical data on the involvement of zinc in the pathophysiology and treatment of seizures/epilepsy. Furthermore, the potential of targeting elements associated with zinc signaling or homeostasis and zinc levels as a therapeutic strategy for epilepsy is discussed.
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Affiliation(s)
- Urszula Doboszewska
- Department of Animal Physiology, Institute of Biology and Biochemistry, Faculty of Biology and Biotechnology, Maria Curie-Skłodowska University, Lublin, Poland.
| | - Katarzyna Młyniec
- Department of Pharmacobiology, Jagiellonian University Medical College, Kraków, Poland
| | - Aleksandra Wlaź
- Department of Pathophysiology, Medical University of Lublin, Lublin, Poland
| | - Ewa Poleszak
- Department of Applied Pharmacy, Medical University of Lublin, Lublin, Poland
| | - Gabriel Nowak
- Department of Pharmacobiology, Jagiellonian University Medical College, Kraków, Poland; Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Piotr Wlaź
- Department of Animal Physiology, Institute of Biology and Biochemistry, Faculty of Biology and Biotechnology, Maria Curie-Skłodowska University, Lublin, Poland
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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.
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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
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45
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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.
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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.)
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46
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Auerbach DS, Biton Y, Polonsky B, McNitt S, Gross RA, Dirksen RT, Moss AJ. Risk of cardiac events in Long QT syndrome patients when taking antiseizure medications. Transl Res 2018; 191:81-92.e7. [PMID: 29121487 PMCID: PMC5733703 DOI: 10.1016/j.trsl.2017.10.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 10/02/2017] [Accepted: 10/07/2017] [Indexed: 12/29/2022]
Abstract
Many antiseizure medications (ASMs) affect ion channel function. We investigated whether ASMs alter the risk of cardiac events in patients with corrected QT (QTc) prolongation. The study included people from the Rochester-based Long QT syndrome (LQTS) Registry with baseline QTc prolongation and history of ASM therapy (n = 296). Using multivariate Anderson-Gill models, we assessed the risk of recurrent cardiac events associated with ASM therapy. We stratified by LQTS genotype and predominant mechanism of ASM action (Na+ channel blocker and gamma-aminobutyric acid modifier.) There was an increased risk of cardiac events when participants with QTc prolongation were taking vs off ASMs (HR 1.65, 95% confidence interval [CI] 1.36-2.00, P < 0.001). There was an increased risk of cardiac events when LQTS2 (HR 1.49, 95% CI 1.03-2.15, P = 0.036) but not LQTS1 participants were taking ASMs (interaction, P = 0.016). Na+ channel blocker ASMs were associated with an increased risk of cardiac events in participants with QTc prolongation, specifically LQTS2, but decreased risk in LQTS1. The increased risk when taking all ASMs and Na+ channel blocker ASMs was attenuated by concurrent beta-adrenergic blocker therapy (interaction, P < 0.001). Gamma-aminobutyric acid modifier ASMs were associated with an increased risk of events in patients not concurrently treated with beta-adrenergic blockers. Female participants were at an increased risk of cardiac events while taking all ASMs and each class of ASMs. Despite no change in overall QTc duration, pharmacogenomic analyses set the stage for future prospective clinical and mechanistic studies to validate that ASMs with predominantly Na+ channel blocking actions are deleterious in LQTS2, but protective in LQTS1.
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Affiliation(s)
- David S Auerbach
- Department of Medicine, Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, NY; Department of Pharmacology & Physiology, University of Rochester School of Medicine and Dentistry, Rochester, NY.
| | - Yitschak Biton
- Department of Medicine, Heart Research Follow up Program, University of Rochester School of Medicine and Dentistry, Rochester, NY; Department of Cardiology, Massachusetts General Hospital and Harvard Medical School, Boston, Mass
| | - Bronislava Polonsky
- Department of Medicine, Heart Research Follow up Program, University of Rochester School of Medicine and Dentistry, Rochester, NY
| | - Scott McNitt
- Department of Medicine, Heart Research Follow up Program, University of Rochester School of Medicine and Dentistry, Rochester, NY
| | - Robert A Gross
- Department of Pharmacology & Physiology, University of Rochester School of Medicine and Dentistry, Rochester, NY; Department of Neurology, University of Rochester School of Medicine and Dentistry, Rochester, NY
| | - Robert T Dirksen
- Department of Pharmacology & Physiology, University of Rochester School of Medicine and Dentistry, Rochester, NY
| | - Arthur J Moss
- Department of Medicine, Heart Research Follow up Program, University of Rochester School of Medicine and Dentistry, Rochester, NY
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Modulation of Abnormal Sodium Channel Currents in Heart and Brain: Hope for SUDEP Prevention and Seizure Reduction. Epilepsy Curr 2017; 17:306-310. [PMID: 29225548 DOI: 10.5698/1535-7597.17.5.306] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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48
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Anderson LL, Hawkins NA, Thompson CH, Kearney JA, George AL. Unexpected Efficacy of a Novel Sodium Channel Modulator in Dravet Syndrome. Sci Rep 2017; 7:1682. [PMID: 28490751 PMCID: PMC5431801 DOI: 10.1038/s41598-017-01851-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 04/04/2017] [Indexed: 01/03/2023] Open
Abstract
Dravet syndrome, an epileptic encephalopathy affecting children, largely results from heterozygous loss-of-function mutations in the brain voltage-gated sodium channel gene SCN1A. Heterozygous Scn1a knockout (Scn1a +/-) mice recapitulate the severe epilepsy phenotype of Dravet syndrome and are an accepted animal model. Because clinical observations suggest conventional sodium channel blocking antiepileptic drugs may worsen the disease, we predicted the phenotype of Scn1a +/- mice would be exacerbated by GS967, a potent, unconventional sodium channel blocker. Unexpectedly, GS967 significantly improved survival of Scn1a +/- mice and suppressed spontaneous seizures. By contrast, lamotrigine exacerbated the seizure phenotype. Electrophysiological recordings of acutely dissociated neurons revealed that chronic GS967-treatment had no impact on evoked action potential firing frequency of interneurons, but did suppress aberrant spontaneous firing of pyramidal neurons and was associated with significantly lower sodium current density. Lamotrigine had no effects on neuronal excitability of either neuron subtype. Additionally, chronically GS967-treated Scn1a +/- mice exhibited normalized pyramidal neuron sodium current density and reduced hippocampal NaV1.6 protein levels, whereas lamotrigine treatment had no effect on either pyramidal neuron sodium current or hippocampal NaV1.6 levels. Our findings demonstrate unexpected efficacy of a novel sodium channel blocker in Dravet syndrome and suggest a potential mechanism involving a secondary change in NaV1.6.
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Affiliation(s)
- Lyndsey L Anderson
- 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
| | - Christopher H Thompson
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Jennifer A Kearney
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Alfred L George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
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Karagueuzian HS, Pezhouman A, Angelini M, Olcese R. Enhanced Late Na and Ca Currents as Effective Antiarrhythmic Drug Targets. Front Pharmacol 2017; 8:36. [PMID: 28220073 PMCID: PMC5292429 DOI: 10.3389/fphar.2017.00036] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 01/18/2017] [Indexed: 11/30/2022] Open
Abstract
While recent advances clarified the molecular and cellular modes of action of antiarrhythmic drugs (AADs), their link to suppression of dynamical arrhythmia mechanisms remains only partially understood. The current classifications of AADs (Classes I, III, and IV) rely on blocking peak Na, K and L-type calcium currents (ICa,L), with Class II with dominant beta receptor blocking activity and Class V including drugs with diverse classes of actions. The discovery that the calcium and redox sensor, cardiac Ca/calmodulin-dependent protein kinase II (CaMKII) enhances both the late Na (INa-L) and the late ICa,L in patients at high risk of VT/VF provided a new and a rational AAD target. Pathological rise of either or both of INa-L and late ICa,L are demonstrated to promote cellular early afterdepolarizations (EADs) and EAD-mediated triggered activity that can initiate VT/VF in remodeled hearts. Selective inhibition of the INa-L without affecting their peak transients with the highly specific prototype drug, GS-967 suppresses these EAD-mediated VT/VFs. As in the case of INa-L, selective inhibition of the late ICa,L without affecting its peak with the prototype drug, roscovitine suppressed oxidative EAD-mediated VT/VF. These findings indicate that specific blockers of the late inward currents without affecting their peaks (gating modifiers), offer a new and effective AAD class action i.e., “Class VI.” The development of safe drugs with selective Class VI actions provides a rational and effective approach to treat VT/VF particularly in cardiac conditions associated with enhanced CaMKII activity such as heart failure.
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Affiliation(s)
- Hrayr S Karagueuzian
- Translational Arrhythmia Section, David Geffen School of Medicine, University of California, Los AngelesLos Angeles, CA, USA; Cardiovascular Research Laboratory, Departments of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los AngelesLos Angeles, CA, USA
| | - Arash Pezhouman
- Translational Arrhythmia Section, David Geffen School of Medicine, University of California, Los AngelesLos Angeles, CA, USA; Cardiovascular Research Laboratory, Departments of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los AngelesLos Angeles, CA, USA
| | - Marina Angelini
- Department of Anesthesiology and Perioperative Medicine, David Geffen School of Medicine, University of California, Los Angeles Los Angeles, CA, USA
| | - Riccardo Olcese
- Cardiovascular Research Laboratory, Departments of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los AngelesLos Angeles, CA, USA; Department of Anesthesiology and Perioperative Medicine, David Geffen School of Medicine, University of California, Los AngelesLos Angeles, CA, USA; Department of Physiology, David Geffen School of Medicine, University of California, Los AngelesLos Angeles, CA, USA
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50
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Terragni B, Scalmani P, Colombo E, Franceschetti S, Mantegazza M. Ranolazine vs phenytoin: greater effect of ranolazine on the transient Na(+) current than on the persistent Na(+) current in central neurons. Neuropharmacology 2016; 110:223-236. [PMID: 27450092 DOI: 10.1016/j.neuropharm.2016.06.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 06/08/2016] [Accepted: 06/26/2016] [Indexed: 12/13/2022]
Abstract
Voltage-gated Na(+) channels (NaV) are involved in pathologies and are important targets of drugs (NaV-blockers), e.g. some anti-epileptic drugs (AEDs). Besides the fast inactivating transient Na(+) current (INaT), they generate a slowly inactivating "persistent" current (INaP). Ranolazine, a NaV-blocker approved for treatment of angina pectoris, is considered a preferential inhibitor of INaP and has been proposed as a novel AED. Although it is thought that classic NaV-blockers used as AEDs target mainly INaT, they can also reduce INaP. It is important to disclose specific features of novel NaV-blockers, which could be necessary for their effect as AEDs in drug resistant patients. We have compared the action of ranolazine and of the classic AED phenytoin in transfected cells expressing the neuronal NaV1.1 Na(+) channel and in neurons of neocortical slices. Our results show that the relative block of INaT versus INaP of ranolazine and phenytoin is variable and depends on Na(+) current activation conditions. Strikingly, ranolazine blocks with less efficacy INaP and more efficacy INaT than phenytoin in conditions mimicking pathological states (i.e. high frequency firing and long lasting depolarizations). The effects are consistent with binding of ranolazine to both open/pre-open and inactivated states; larger INaT block at high stimulation frequencies is caused by the induction of a slow inactivated state. Thus, contrary than expected, ranolazine is not a better INaP blocker than phenytoin in central neurons, and phenytoin is not a better INaT blocker than ranolazine. Nevertheless, they show a complementary action and could differentially target specific pathological dysfunctions.
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Affiliation(s)
- Benedetta Terragni
- Department of Neurophysiology and Diagnostic Epileptology, IRCCS Foundation C. Besta Neurological Institute, 20133, Milan, Italy.
| | - Paolo Scalmani
- Department of Neurophysiology and Diagnostic Epileptology, IRCCS Foundation C. Besta Neurological Institute, 20133, Milan, Italy.
| | - Elisa Colombo
- Department of Neurophysiology and Diagnostic Epileptology, IRCCS Foundation C. Besta Neurological Institute, 20133, Milan, Italy.
| | - Silvana Franceschetti
- Department of Neurophysiology and Diagnostic Epileptology, IRCCS Foundation C. Besta Neurological Institute, 20133, Milan, Italy.
| | - Massimo Mantegazza
- Institute of Molecular and Cellular Pharmacology (IPMC), CNRS UMR7275, 06560, Valbonne-Sophia Antipolis, France; University of the Côte d'Azur (UCA), 06560, Valbonne-Sophia Antipolis, France; Inserm, 06560, Valbonne-Sophia Antipolis, France.
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