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Gu J, Shao W, Liu L, Wang Y, Yang Y, Zhang Z, Wu Y, Xu Q, Gu L, Zhang Y, Shen Y, Zhao H, Zeng C, Zhang H. Challenges and future directions of SUDEP models. Lab Anim (NY) 2024; 53:226-243. [PMID: 39187733 DOI: 10.1038/s41684-024-01426-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 08/02/2024] [Indexed: 08/28/2024]
Abstract
Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death among patients with epilepsy, causing a global public health burden. The underlying mechanisms of SUDEP remain elusive, and effective prevention or treatment strategies require further investigation. A major challenge in current SUDEP research is the lack of an ideal model that maximally mimics the human condition. Animal models are important for revealing the potential pathogenesis of SUDEP and preventing its occurrence; however, they have potential limitations due to species differences that prevent them from precisely replicating the intricate physiological and pathological processes of human disease. This Review provides a comprehensive overview of several available SUDEP animal models, highlighting their pros and cons. More importantly, we further propose the establishment of an ideal model based on brain-computer interfaces and artificial intelligence, hoping to offer new insights into potential advancements in SUDEP research. In doing so, we hope to provide valuable information for SUDEP researchers, offer new insights into the pathogenesis of SUDEP and open new avenues for the development of strategies to prevent SUDEP.
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Affiliation(s)
- JiaXuan Gu
- Department of Anesthesiology, the Fourth Clinical School of Medicine, Zhejiang Chinese Medical University, Hangzhou, China
| | - WeiHui Shao
- Department of Anesthesiology, the Fourth Clinical School of Medicine, Zhejiang Chinese Medical University, Hangzhou, China
| | - Lu Liu
- Department of Anesthesiology, Zhejiang University School of Medicine, Hangzhou, China
| | - YuLing Wang
- Department of Anesthesiology, the Fourth Clinical School of Medicine, Zhejiang Chinese Medical University, Hangzhou, China
| | - Yue Yang
- Department of Anesthesiology, the Fourth Clinical School of Medicine, Zhejiang Chinese Medical University, Hangzhou, China
| | - ZhuoYue Zhang
- Department of Anesthesiology, Zhejiang University School of Medicine, Hangzhou, China
| | - YaXuan Wu
- Department of Anesthesiology, the Fourth Clinical School of Medicine, Zhejiang Chinese Medical University, Hangzhou, China
| | - Qing Xu
- Department of Anesthesiology, Zhejiang University School of Medicine, Hangzhou, China
| | - LeYuan Gu
- Department of Anesthesiology, the Fourth Clinical School of Medicine, Zhejiang Chinese Medical University, Hangzhou, China
| | - YuanLi Zhang
- Department of Anesthesiology, the Fourth Clinical School of Medicine, Zhejiang Chinese Medical University, Hangzhou, China
| | - Yue Shen
- Department of Anesthesiology, Affiliated Hangzhou First People's Hospital, Westlake University School of Medicine, Hangzhou, China
| | - HaiTing Zhao
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Chang Zeng
- Health Management Center, Xiangya Hospital, Central South University, Changsha, China
| | - HongHai Zhang
- Department of Anesthesiology, the Fourth Clinical School of Medicine, Zhejiang Chinese Medical University, Hangzhou, China.
- Department of Anesthesiology, Zhejiang University School of Medicine, Hangzhou, China.
- Department of Anesthesiology, Affiliated Hangzhou First People's Hospital, Westlake University School of Medicine, Hangzhou, China.
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Feng H, Clatot J, Kaneko K, Flores-Mendez M, Wengert ER, Koutcher C, Hoddeson E, Lopez E, Lee D, Arias L, Liang Q, Zhang X, Somarowthu A, Covarrubias M, Gunthorpe MJ, Large CH, Akizu N, Goldberg EM. Targeted therapy improves cellular dysfunction, ataxia, and seizure susceptibility in a model of a progressive myoclonus epilepsy. Cell Rep Med 2024; 5:101389. [PMID: 38266642 PMCID: PMC10897515 DOI: 10.1016/j.xcrm.2023.101389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 11/09/2023] [Accepted: 12/20/2023] [Indexed: 01/26/2024]
Abstract
The recurrent variant KCNC1-p.Arg320His causes progressive myoclonus epilepsy (EPM) type 7, defined by progressive myoclonus, epilepsy, and ataxia, and is without effective treatment. KCNC1 encodes the voltage-gated potassium channel subunit Kv3.1, specifically expressed in high-frequency-firing neurons. Variant subunits act via loss of function; hence, EPM7 pathogenesis may involve impaired excitability of Kv3.1-expressing neurons, while enhancing Kv3 activity could represent a viable therapeutic strategy. We generate a mouse model, Kcnc1-p.Arg320His/+, which recapitulates the core features of EPM7, including progressive ataxia and seizure susceptibility. Kv3.1-expressing cerebellar granule cells and neocortical parvalbumin-positive GABAergic interneurons exhibit abnormalities consistent with Kv3 channel dysfunction. A Kv3-specific positive modulator (AUT00206) selectively enhances the firing frequency of Kv3.1-expressing neurons and improves motor function and seizure susceptibility in Kcnc1-Arg320His/+ mice. This work identifies a cellular and circuit basis of dysfunction in EPM7 and demonstrates that Kv3 positive modulators such as AUT00206 have therapeutic potential for the treatment of EPM7.
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Affiliation(s)
- Huijie Feng
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Jerome Clatot
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; The Epilepsy Neurogenetics Initiative, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Keisuke Kaneko
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Anesthesiology, Nihon University, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan
| | - Marco Flores-Mendez
- The Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Eric R Wengert
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Carly Koutcher
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Emily Hoddeson
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Emily Lopez
- The University of Pennsylvania School of Arts and Sciences, Philadelphia, PA, USA
| | - Demetrius Lee
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Leroy Arias
- The University of Pennsylvania School of Arts and Sciences, Philadelphia, PA, USA
| | - Qiansheng Liang
- Department of Neuroscience and Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Xiaohong Zhang
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Ala Somarowthu
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Manuel Covarrubias
- Department of Neuroscience and Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Martin J Gunthorpe
- Autifony Therapeutics, Ltd., Stevenage Bioscience Catalyst, Stevenage SG1 2FX, UK
| | - Charles H Large
- Autifony Therapeutics, Ltd., Stevenage Bioscience Catalyst, Stevenage SG1 2FX, UK
| | - Naiara Akizu
- The Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Departments of Pathology & Laboratory Medicine, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Ethan M Goldberg
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; The Epilepsy Neurogenetics Initiative, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Neurology, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Neuroscience, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
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Smith J, Richerson G, Kouchi H, Duprat F, Mantegazza M, Bezin L, Rheims S. Are we there yet? A critical evaluation of sudden and unexpected death in epilepsy models. Epilepsia 2024; 65:9-25. [PMID: 37914406 DOI: 10.1111/epi.17812] [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: 08/04/2023] [Revised: 10/11/2023] [Accepted: 10/31/2023] [Indexed: 11/03/2023]
Abstract
Although animal models have helped to elaborate meaningful hypotheses about the pathophysiology of sudden and unexpected death in epilepsy (SUDEP), specific prevention strategies are still lacking, potentially reflecting the limitations of these models and the intrinsic difficulties of investigating SUDEP. The interpretation of preclinical data and their translation to diagnostic and therapeutic developments in patients thus require a high level of confidence in their relevance to model the human situation. Preclinical models of SUDEP are heterogeneous and include rodent and nonrodent species. A critical aspect is whether the animals have isolated seizures exclusively induced by a specific trigger, such as models where seizures are elicited by electrical stimulation, pharmacological intervention, or DBA mouse strains, or whether they suffer from epilepsy with spontaneous seizures, with or without spontaneous SUDEP, either of nongenetic epilepsy etiology or from genetically based developmental and epileptic encephalopathies. All these models have advantages and potential disadvantages, but it is important to be aware of these limitations to interpret data appropriately in a translational perspective. The majority of models with spontaneous seizures are of a genetic basis, whereas SUDEP cases with a genetic basis represent only a small proportion of the total number. In almost all models, cardiorespiratory arrest occurs during the course of the seizure, contrary to that in patients observed at the time of death, potentially raising the issue of whether we are studying models of SUDEP or models of periseizure death. However, some of these limitations are impossible to avoid and can in part be dependent on specific features of SUDEP, which may be difficult to model. Several preclinical tools are available to address certain gaps in SUDEP pathophysiology, which can be used to further validate current preclinical models.
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Affiliation(s)
- Jonathon Smith
- Lyon Neuroscience Research Center (CRNL, INSERM U1028/CNRS UMR 5292, Lyon 1 University), Lyon, France
| | - George Richerson
- Department of Neurology, University of Iowa, Iowa City, Iowa, USA
| | - Hayet Kouchi
- Lyon Neuroscience Research Center (CRNL, INSERM U1028/CNRS UMR 5292, Lyon 1 University), Lyon, France
| | - Fabrice Duprat
- University Cote d'Azur, Valbonne-Sophia Antipolis, France
- CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology, Valbonne-Sophia Antipolis, France
- Inserm, Valbonne-Sophia Antipolis, France
| | - Massimo Mantegazza
- University Cote d'Azur, Valbonne-Sophia Antipolis, France
- CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology, Valbonne-Sophia Antipolis, France
- Inserm, Valbonne-Sophia Antipolis, France
| | - Laurent Bezin
- Lyon Neuroscience Research Center (CRNL, INSERM U1028/CNRS UMR 5292, Lyon 1 University), Lyon, France
| | - Sylvain Rheims
- Lyon Neuroscience Research Center (CRNL, INSERM U1028/CNRS UMR 5292, Lyon 1 University), Lyon, France
- Department of Functional Neurology and Epileptology, Hospices Civils de Lyon and Lyon 1 University, Lyon, France
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Medvedeva TM, Sysoeva MV, Sysoev IV, Vinogradova LV. Intracortical functional connectivity dynamics induced by reflex seizures. Exp Neurol 2023; 368:114480. [PMID: 37454711 DOI: 10.1016/j.expneurol.2023.114480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 06/13/2023] [Accepted: 07/12/2023] [Indexed: 07/18/2023]
Abstract
Functional connectivity analysis is gaining more interest due to its promising clinical applications. To study network mechanisms underlying seizure termination and postictal depression, we explore dynamics of interhemispheric functional connectivity near the offset of focal and bilateral seizures in the experimental model of reflex audiogenic epilepsy. In the model, seizures and spreading depression are induced by sound stimulation of genetically predisposed rodents. We characterize temporal evolution of seizure-associated coupling dynamics in the frontoparietal cortex during late ictal, immediate postictal and interictal resting states, using two measures applied to local field potentials recorded in awake epileptic rats. Signals were analyzed with mean phase coherence index in delta (1-4 Hz), theta (4-10 Hz) beta (10-25 Hz) and gamma (25-50 Hz) frequency bands and mutual information function. The study shows that reflex seizures elicit highly dynamic changes in interhemispheric functional coupling with seizure-, region- and frequency-specific patterns of increased and decreased connectivity during late ictal and immediate postictal periods. Also, secondary generalization of recurrent seizures (kindling) is associated with pronounced alterations in resting-state functional connectivity - an early wideband decrease and a subsequent beta-gamma increase. The findings show that intracortical functional connectivity is dynamically modified in response to seizures on short and long timescales, suggesting the existence of activity-dependent plastic network alterations that may promote or prevent seizure propagation within the cortex and underlie postictal behavioral impairments.
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Affiliation(s)
- Tatiana M Medvedeva
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
| | - Marina V Sysoeva
- Yuri Gagarin State Technical University of Saratov, Saratov, Russia
| | - Ilya V Sysoev
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia; Saratov State University, Saratov, Russia
| | - Lyudmila V Vinogradova
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia.
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Bosco F, Guarnieri L, Leo A, Tallarico M, Gallelli L, Rania V, Citraro R, De Sarro G. Audiogenic epileptic DBA/2 mice strain as a model of genetic reflex seizures and SUDEP. Front Neurol 2023; 14:1223074. [PMID: 37681009 PMCID: PMC10481168 DOI: 10.3389/fneur.2023.1223074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 07/14/2023] [Indexed: 09/09/2023] Open
Abstract
Epilepsy is a chronic neurological disease characterized by abnormal brain activity, which results in repeated spontaneous seizures. Sudden unexpected death in epilepsy (SUDEP) is the leading cause of seizure-related premature death, particularly in drug-resistant epilepsy patients. The etiology of SUDEP is a structural injury to the brain that is not fully understood, but it is frequently associated with poorly controlled and repeated generalized tonic-clonic seizures (GTCSs) that cause cardiorespiratory and autonomic dysfunctions, indicating the involvement of the brainstem. Both respiratory and cardiac abnormalities have been observed in SUDEP, but not much progress has been made in their prevention. Owing to the complexity of SUDEP, experimental animal models have been used to investigate cardiac and/or respiratory dysregulation due to or associated with epileptic seizures that may contribute to death in humans. Numerous rodent models, especially mouse models, have been developed to better understand epilepsy and SUDEP physiopathology. This review synthesizes the current knowledge about dilute brown agouti coat color (DBA/2) mice as a possible SUDEP model because respiratory arrest (RA) and sudden death induced by audiogenic generalized seizures (AGSs) have been observed in these animals. Respiratory/cardiac dysfunction, brainstem arousal system dysfunction, and alteration of the neurotransmitter systems, which are observed in human SUDEP, have also been observed in these mice. In particular, serotonin (5-HT) alteration and adenosine neurotransmission appear to contribute to not only the pathophysiological mechanisms of medication but also seizure-related respiratory dysfunctions in this animal model. These neurotransmitter systems could be the relevant targets for medication development for chronic epilepsy and SUDEP prevention. We reviewed data on AGSs in DBA/2 mice and the relevance of this model of generalized tonic-clonic epilepsy to human SUDEP. Furthermore, the advantages of using this strain prone to AGSs for the identification of possible new therapeutic targets and treatment options have also been assessed.
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Affiliation(s)
- Francesca Bosco
- Section of Pharmacology, Science of Health Department, School of Medicine, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
| | - Lorenza Guarnieri
- Section of Pharmacology, Science of Health Department, School of Medicine, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
| | - Antonio Leo
- Section of Pharmacology, Science of Health Department, School of Medicine, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
- Research Center FAS@UMG, Department of Health Science, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
| | - Martina Tallarico
- Section of Pharmacology, Science of Health Department, School of Medicine, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
| | - Luca Gallelli
- Section of Pharmacology, Science of Health Department, School of Medicine, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
- Research Center FAS@UMG, Department of Health Science, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
| | - Vincenzo Rania
- Section of Pharmacology, Science of Health Department, School of Medicine, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
| | - Rita Citraro
- Section of Pharmacology, Science of Health Department, School of Medicine, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
- Research Center FAS@UMG, Department of Health Science, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
| | - Giovambattista De Sarro
- Section of Pharmacology, Science of Health Department, School of Medicine, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
- Research Center FAS@UMG, Department of Health Science, University “Magna Graecia” of Catanzaro, Catanzaro, Italy
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Brun L, Borloz E, Felix MS, Louis Durand J, Villard L. Ultrasound-induced seizures in a mouse model of KCNQ2-NEO-DEE. Epilepsy Res 2023; 193:107160. [PMID: 37187037 DOI: 10.1016/j.eplepsyres.2023.107160] [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: 02/21/2023] [Revised: 04/04/2023] [Accepted: 05/01/2023] [Indexed: 05/17/2023]
Abstract
PURPOSE KCNQ2 neonatal developmental and epileptic encephalopathy (NEO-DEE) is characterized by intractable seizures accompanied by an abnormal neurodevelopment. In a mouse model of NEO-DEE carrying the p.(Thr274Met) variant of Kcnq2, spontaneous generalized seizures occur unexpectedly preventing controlled studies and highlighting the necessity for a customized setup to trigger seizures on demand. We aimed to obtain a stable and objective read-out to control the efficacy of new antiepileptic drugs or to test seizure susceptibility. We developed a protocol to trigger ultrasound-induced seizures (UIS) on demand in this model. METHODS We tested the ability of our protocol to induce seizures at four developmental stages in the Kcnq2p.(Thr274Met/+) mouse model. We mapped the activated brain regions using c-fos protein labeling 2 h after seizure induction. RESULTS We show that the UIS have the same phenotypic expression and the same severity as spontaneous generalized seizures (SGS) in the Kcnq2-NEO-DEE mouse model. The developmental period during which mice exhibit SGS corresponds to the period during which Kcnq2p.(Thr274Met/+) mice are the most susceptible to US. C-fos labeling reveals a subset of 6 brain regions activated 2 h after the induction of the seizure. The same regions were identified in the context of seizure induction in other rodent models. CONCLUSION This study provides a non-invasive and easy to use method to induce seizures in a Kcnq2-NEO-DEE mouse model and documents early neuronal activation in specific brain regions. This method can be used to test the efficacy of new antiepileptic approaches for this intractable form of genetic epilepsy.
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Affiliation(s)
- Lucile Brun
- Aix Marseille Univ, Inserm, MMG, Marseille, France
| | | | | | | | - Laurent Villard
- Aix Marseille Univ, Inserm, MMG, Marseille, France; Service de Génétique Médicale, AP-HM, Hôpital de La Timone, Marseille, France.
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Faingold CL, Feng HJ. A unified hypothesis of SUDEP: Seizure-induced respiratory depression induced by adenosine may lead to SUDEP but can be prevented by autoresuscitation and other restorative respiratory response mechanisms mediated by the action of serotonin on the periaqueductal gray. Epilepsia 2023; 64:779-796. [PMID: 36715572 PMCID: PMC10673689 DOI: 10.1111/epi.17521] [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: 10/07/2022] [Revised: 01/20/2023] [Accepted: 01/27/2023] [Indexed: 01/31/2023]
Abstract
Sudden unexpected death in epilepsy (SUDEP) is a major cause of death in people with epilepsy (PWE). Postictal apnea leading to cardiac arrest is the most common sequence of terminal events in witnessed cases of SUDEP, and postconvulsive central apnea has been proposed as a potential biomarker of SUDEP susceptibility. Research in SUDEP animal models has led to the serotonin and adenosine hypotheses of SUDEP. These neurotransmitters influence respiration, seizures, and lethality in animal models of SUDEP, and are implicated in human SUDEP cases. Adenosine released during seizures is proposed to be an important seizure termination mechanism. However, adenosine also depresses respiration, and this effect is mediated, in part, by inhibition of neuronal activity in subcortical structures that modulate respiration, including the periaqueductal gray (PAG). Drugs that enhance the action of adenosine increase postictal death in SUDEP models. Serotonin is also released during seizures, but enhances respiration in response to an elevated carbon dioxide level, which often occurs postictally. This effect of serotonin can potentially compensate, in part, for the adenosine-mediated respiratory depression, acting to facilitate autoresuscitation and other restorative respiratory response mechanisms. A number of drugs that enhance the action of serotonin prevent postictal death in several SUDEP models and reduce postictal respiratory depression in PWE. This effect of serotonergic drugs may be mediated, in part, by actions on brainstem sites that modulate respiration, including the PAG. Enhanced activity in the PAG increases respiration in response to hypoxia and other exigent conditions and can be activated by electrical stimulation. Thus, we propose the unifying hypothesis that seizure-induced adenosine release leads to respiratory depression. This can be reversed by serotonergic action on autoresuscitation and other restorative respiratory responses acting, in part, via the PAG. Therefore, we hypothesize that serotonergic or direct activation of this brainstem site may be a useful approach for SUDEP prevention.
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Affiliation(s)
- Carl L Faingold
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois, USA
- Department of Neurology, Southern Illinois University School of Medicine, Springfield, Illinois, USA
| | - Hua-Jun Feng
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Anesthesia, Harvard Medical School, Boston, Massachusetts, USA
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Gu B, Adeli H. Toward automated prediction of sudden unexpected death in epilepsy. Rev Neurosci 2022; 33:877-887. [PMID: 35619127 DOI: 10.1515/revneuro-2022-0024] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 04/19/2022] [Indexed: 12/14/2022]
Abstract
Sudden unexpected death in epilepsy (SUDEP) is a devastating yet overlooked complication of epilepsy. The rare and complex nature of SUDEP makes it challenging to study. No prediction or prevention of SUDEP is currently available in a clinical setting. In the past decade, significant advances have been made in our knowledge of the pathophysiologic cascades that lead to SUDEP. In particular, studies of brain, heart, and respiratory functions in both human patients at the epilepsy monitoring unit and animal models during fatal seizures provide critical information to integrate computational tools for SUDEP prediction. The rapid advances in automated seizure detection and prediction algorithms provide a fundamental framework for their adaption in predicting SUDEP. If a SUDEP can be predicted, then there will be a potential for medical intervention to be administered, either by their caregivers or via an implanted device automatically delivering electrical stimulation or medication, and finally save lives from fatal seizures. This article presents recent developments of SUDEP studies focusing on the pathophysiologic basis of SUDEP and computational implications of machine learning techniques that can be adapted and extended for SUDEP prediction. This article also discusses some novel ideas for SUDEP prediction and rescue including principal component analysis and closed-loop intervention.
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Affiliation(s)
- Bin Gu
- Department of Neuroscience, Ohio State University, Columbus, OH 43210, USA
| | - Hojjat Adeli
- Department of Neuroscience, Ohio State University, Columbus, OH 43210, USA.,Department of Biomedical Informatics, Ohio State University, Columbus, OH 43210, USA
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Zhu L, Chen D, Lin X, Liu L. Gene expression profile for different susceptibilities to sound stimulation: a comparative study on brainstems between two inbred laboratory mouse strains. BMC Genomics 2022; 23:783. [PMID: 36451107 PMCID: PMC9710100 DOI: 10.1186/s12864-022-09016-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 11/16/2022] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND DBA/1 mice have a higher susceptibility to generalized audiogenic seizures (AGSz) and seizure-induced respiratory arrest (S-IRA) than C57/BL6 mice. The gene expression profile might be potentially related to this difference. This study aimed to investigate the susceptibility difference in AGSz and S-IRA between DBA/1 and C57BL/6 mice by profiling long noncoding RNAs (lncRNAs) and mRNA expression. METHODS We compared lncRNAs and mRNAs from the brainstem of the two strains with Arraystar Mouse lncRNA Microarray V3.0 (Arraystar, Rockville, MD). Gene Ontology (GO) and pathway analyses were performed to determine the potentially related biological functions and pathways based on differentially expressed mRNAs. qRT-PCR was carried out to validate the results. RESULTS A total of 897 lncRNAs and 438 mRNAs were differentially expressed (fold change ≥2, P < 0.05), of which 192 lncRNAs were upregulated and 705 lncRNAs were downregulated. A total of 138 mRNAs were upregulated, and 300 mRNAs were downregulated. In terms of specific mRNAs, Htr5b, Gabra2, Hspa1b and Gfra1 may be related to AGSz or S-IRA. Additionally, lncRNA Neat1 may participate in the difference in susceptibility. GO and pathway analyses suggested that TGF-β signaling, metabolic process and MHC protein complex could be involved in these differences. Coexpression analysis identified 9 differentially expressed antisense lncRNAs and 115 long intergenic noncoding RNAs (lincRNAs), and 2010012P19Rik and its adjacent RNA Tnfsf12-Tnfsf13 may have participated in S-IRA by regulating sympathetic neuron function. The results of the qRT-PCR of five selected lncRNAs (AK038711, Gm11762, 1500004A13Rik, AA388235 and Neat1) and four selected mRNAs (Hspa1b, Htr5b, Gabra2 and Gfra1) were consistent with those obtained by microarray. CONCLUSION We concluded that TGF-β signaling and metabolic process may contribute to the differential sensitivity to AGSz and S-IRA. Among mRNAs, Htr5b, Gabra2, Hspa1b and Gfra1 could potentially influence the susceptibility. LncRNA Neat1 and 2010012P19Rik may also contribute to the different response to sound stimulation. Further studies should be carried out to explore the underlying functions and mechanisms of differentially expressed RNAs.
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Affiliation(s)
- Lina Zhu
- grid.412901.f0000 0004 1770 1022Department of Neurology, West China Hospital, Sichuan University, Wai Nan Guo Xue Lane 37 #, Chengdu, 610041 Sichuan China
| | - Deng Chen
- grid.412901.f0000 0004 1770 1022Department of Neurology, West China Hospital, Sichuan University, Wai Nan Guo Xue Lane 37 #, Chengdu, 610041 Sichuan China
| | - Xin Lin
- grid.412901.f0000 0004 1770 1022Department of Neurology, West China Hospital, Sichuan University, Wai Nan Guo Xue Lane 37 #, Chengdu, 610041 Sichuan China
| | - Ling Liu
- grid.412901.f0000 0004 1770 1022Department of Neurology, West China Hospital, Sichuan University, Wai Nan Guo Xue Lane 37 #, Chengdu, 610041 Sichuan China
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Rodent Models of Audiogenic Epilepsy: Genetic Aspects, Advantages, Current Problems and Perspectives. Biomedicines 2022; 10:biomedicines10112934. [PMID: 36428502 PMCID: PMC9687921 DOI: 10.3390/biomedicines10112934] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/10/2022] [Accepted: 11/11/2022] [Indexed: 11/18/2022] Open
Abstract
Animal models of epilepsy are of great importance in epileptology. They are used to study the mechanisms of epileptogenesis, and search for new genes and regulatory pathways involved in the development of epilepsy as well as screening new antiepileptic drugs. Today, many methods of modeling epilepsy in animals are used, including electroconvulsive, pharmacological in intact animals, and genetic, with the predisposition for spontaneous or refractory epileptic seizures. Due to the simplicity of manipulation and universality, genetic models of audiogenic epilepsy in rodents stand out among this diversity. We tried to combine data on the genetics of audiogenic epilepsy in rodents, the relevance of various models of audiogenic epilepsy to certain epileptic syndromes in humans, and the advantages of using of rodent strains predisposed to audiogenic epilepsy in current epileptology.
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Wenker IC, Boscia AR, Lewis C, Tariq A, Miralles R, Hanflink JC, Saraf P, Patel MK. Forebrain epileptiform activity is not required for seizure-induced apnea in a mouse model of Scn8a epilepsy. Front Neural Circuits 2022; 16:1002013. [PMID: 36160949 PMCID: PMC9490431 DOI: 10.3389/fncir.2022.1002013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Accepted: 08/19/2022] [Indexed: 11/24/2022] Open
Abstract
Sudden unexpected death in epilepsy (SUDEP) accounts for the deaths of 8-17% of patients with epilepsy. Although the mechanisms of SUDEP are essentially unknown, one proposed mechanism is respiratory arrest initiated by a convulsive seizure. In mice, we have previously observed that extended apnea occurs during the tonic phase of seizures. Although often survived, tonic seizures became fatal when breathing did not immediately recover postictally. We also found that respiratory muscles were tonically contracted during the apnea, suggesting that muscle contraction could be the cause of apnea. In the present study, we tested the hypothesis that pyramidal neurons of the motor cortex drive motor units during the tonic phase, which produces apnea. Mice harboring the patient-derived N1768D point mutation of an Scn8a allele were crossed with transgenic mice such that inhibitory Designer Receptors Exclusively Activated by Designer Drugs (DREADD) receptors were selectively expressed in excitatory forebrain neurons. We then triggered audiogenic and hippocampal (HC) stimulated seizures under control conditions and when excitatory forebrain neurons were inhibited with the synthetic ligand Clozapine-N-Oxide (CNO). We found that inhibition with CNO was sufficient to increase seizure threshold of HC stimulated, but not audiogenic, seizures. In addition, regardless of seizure type, CNO nearly eliminated epileptiform activity that occurred proximal to the tonic phase; however, the seizure behaviors, notably the tonic phase and concomitant apnea, were unchanged. We interpret these results to indicate that while cortical neurons are likely critical for epileptogenesis and seizure initiation, the behavioral manifestations of tonic seizures are generated by neural circuitry in the mid- and/or hindbrain.
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Respiratory dysfunction in two rodent models of chronic epilepsy and acute seizures and its link with the brainstem serotonin system. Sci Rep 2022; 12:10248. [PMID: 35715469 PMCID: PMC9205882 DOI: 10.1038/s41598-022-14153-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 06/02/2022] [Indexed: 11/22/2022] Open
Abstract
Patients with drug-resistant epilepsy can experience respiratory alterations, notably during seizures. The mechanisms underlying long-term alterations in respiratory function remain unclear. As the brainstem 5-HT system is a prominent modulator of respiratory function, this study aimed at determining whether epilepsy is associated with alterations in both the respiratory function and brainstem serotonin (5-HT) system in rats. Epilepsy was triggered by pilocarpine-induced status epilepticus in rats. Our results showed that 30–50% of epileptic (EPI) rats exhibited a sharp decrease in oxygen consumption (SDOC), low metabolic rate of oxygen, and slow regular ventilation (EPI/SDOC + rats). These alterations were detected only in rats with chronic epilepsy, independent of behavioral seizures, were persistent over time, and not associated with death. In these rats, 5-HT fiber density in the nucleus tractus solitarius was lower than that in the control and EPI/SDOC− rats. Both EPI/SDOC + rats and DBA/2 mice that present with audiogenic-induced seizure followed by fatal respiratory arrest—a model of sudden and expected death in epilepsy—had increased transcript levels of tryptophan hydroxylase 2 and 5-HT presynaptic transporter. Thus, our data support that 5-HT alterations are associated with chronic and acute epilepsy-related respiratory dysfunction.
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Laporte MH, Chi KI, Caudal LC, Zhao N, Schwarz Y, Rolland M, Martinez-Hernandez J, Martineau M, Chatellard C, Denarier E, Mercier V, Lemaître F, Blot B, Moutaux E, Cazorla M, Perrais D, Lanté F, Bruns D, Fraboulet S, Hemming FJ, Kirchhoff F, Sadoul R. Alix is required for activity-dependent bulk endocytosis at brain synapses. PLoS Biol 2022; 20:e3001659. [PMID: 35658004 PMCID: PMC9200306 DOI: 10.1371/journal.pbio.3001659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 06/15/2022] [Accepted: 05/04/2022] [Indexed: 12/04/2022] Open
Abstract
In chemical synapses undergoing high frequency stimulation, vesicle components can be retrieved from the plasma membrane via a clathrin-independent process called activity-dependent bulk endocytosis (ADBE). Alix (ALG-2-interacting protein X/PDCD6IP) is an adaptor protein binding to ESCRT and endophilin-A proteins which is required for clathrin-independent endocytosis in fibroblasts. Alix is expressed in neurons and concentrates at synapses during epileptic seizures. Here, we used cultured neurons to show that Alix is recruited to presynapses where it interacts with and concentrates endophilin-A during conditions triggering ADBE. Using Alix knockout (ko) neurons, we showed that this recruitment, which requires interaction with the calcium-binding protein ALG-2, is necessary for ADBE. We also found that presynaptic compartments of Alix ko hippocampi display subtle morphological defects compatible with flawed synaptic activity and plasticity detected electrophysiologically. Furthermore, mice lacking Alix in the forebrain undergo less seizures during kainate-induced status epilepticus and reduced propagation of the epileptiform activity. These results thus show that impairment of ADBE due to the lack of neuronal Alix leads to abnormal synaptic recovery during physiological or pathological repeated stimulations. The adaptor protein Alix (PDCD6IP) is necessary for membrane shaping underlying various biological processes including endocytosis. This study shows that Alix mediates activity-dependent bulk endocytosis and is required for correct synaptic physiology under normal and pathological conditions.
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Affiliation(s)
- Marine H. Laporte
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Department of Cell Biology, University of Geneva, Geneva, Switzerland
- * E-mail: (MHL); (FK); (RS)
| | - Kwang Il Chi
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - Laura C. Caudal
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Na Zhao
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Yvonne Schwarz
- Molecular Neurophysiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Marta Rolland
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - José Martinez-Hernandez
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Universidad Castilla-La Mancha, Albacete, Spain
| | - Magalie Martineau
- Interdisciplinary Institute for Neuroscience, University of Bordeaux-CNRS UMR 5297, Bordeaux, France
| | - Christine Chatellard
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Institut de Biologie Structurale, University Grenoble Alpes—CNRS-CEA UMR 5075, Grenoble, France
| | - Eric Denarier
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - Vincent Mercier
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Department of Biochemistry, University of Geneva, Geneva, Switzerland
| | - Florent Lemaître
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Département des Neurosciences, Centre de Recherche du centre hospitalier de Montréal, Canada
| | - Béatrice Blot
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - Eve Moutaux
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - Maxime Cazorla
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Institut de Neuroscience la Timone, CNRS UMR7289, Marseille, France
| | - David Perrais
- Interdisciplinary Institute for Neuroscience, University of Bordeaux-CNRS UMR 5297, Bordeaux, France
| | - Fabien Lanté
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - Dieter Bruns
- Molecular Neurophysiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Sandrine Fraboulet
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Institute for Advanced Biosciences, Univ. Grenoble Alpes—INSERM U1209—CNRS UMR 5309, Grenoble, France
| | - Fiona J. Hemming
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
- * E-mail: (MHL); (FK); (RS)
| | - Rémy Sadoul
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Institut de Biologie Structurale, University Grenoble Alpes—CNRS-CEA UMR 5075, Grenoble, France
- * E-mail: (MHL); (FK); (RS)
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Xia M, Owen B, Chiang J, Levitt A, Preisinger K, Yan WW, Huffman R, Nobis WP. Disruption of Synaptic Transmission in the Bed Nucleus of the Stria Terminalis Reduces Seizure-Induced Death in DBA/1 Mice and Alters Brainstem E/I Balance. ASN Neuro 2022; 14:17590914221103188. [PMID: 35611439 PMCID: PMC9136462 DOI: 10.1177/17590914221103188] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death in refractory epilepsy patients. Accumulating evidence from recent human studies and animal models suggests that seizure-related respiratory arrest may be important for initiating cardiorespiratory arrest and death. Prior evidence suggests that apnea onset can coincide with seizure spread to the amygdala and that stimulation of the amygdala can reliably induce apneas in epilepsy patients, potentially implicating amygdalar regions in seizure-related respiratory arrest and subsequent postictal hypoventilation and cardiorespiratory death. This study aimed to determine if an extended amygdalar structure, the dorsal bed nucleus of the stria terminalis (dBNST), is involved in seizure-induced respiratory arrest (S-IRA) and death using DBA/1 mice, a mouse strain which has audiogenic seizures (AGS) and a high incidence of postictal respiratory arrest and death. The presence of S-IRA significantly increased c-Fos expression in the dBNST of DBA/1 mice. Furthermore, disruption of synaptic output from the dBNST via viral-induced tetanus neurotoxin (TeNT) significantly improved survival following S-IRA in DBA/1 mice without affecting baseline breathing or hypercapnic (HCVR) and hypoxic ventilatory response (HVR). This disruption in the dBNST resulted in changes to the balance of excitatory/inhibitory (E/I) synaptic events in the downstream brainstem regions of the lateral parabrachial nucleus (PBN) and the periaqueductal gray (PAG). These findings suggest that the dBNST is a potential subcortical forebrain site necessary for the mediation of S-IRA, potentially through its outputs to brainstem respiratory regions.
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Affiliation(s)
| | | | | | | | | | | | | | - William P. Nobis
- Department of Neurology, Vanderbilt University Medical Center, 6130A MRB 3/Bio Sci Building, 465 21st Ave S, Nashville, TN 37235, USA.
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Armstrong JL, Saraf TS, Bhatavdekar O, Canal CE. Spontaneous seizures in adult Fmr1 knockout mice: FVB.129P2-Pde6b+ Tyr Fmr1/J. Epilepsy Res 2022; 182:106891. [PMID: 35290907 PMCID: PMC9050957 DOI: 10.1016/j.eplepsyres.2022.106891] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 02/14/2022] [Accepted: 02/17/2022] [Indexed: 01/26/2023]
Abstract
The prevalence of seizures in individuals with fragile X syndrome (FXS) is ~25%; however, there are no reports of spontaneous seizures in the Fmr1 knockout mouse model of FXS. Herein, we report that 48% of adult (median age P96), Fmr1 knockout mice from our colony were found expired in their home cages. We observed and recorded adult Fmr1 knockout mice having spontaneous convulsions in their home cages. In addition, we captured by electroencephalography an adult Fmr1 knockout mouse having a spontaneous seizure-during preictal, ictal, and postictal phases-which confirmed the presence of a generalized seizure. We did not observe this phenotype in control conspecifics or in juvenile (age <P35) Fmr1 knockout mice. We hypothesized that chronic, random, noise perturbations during development caused the phenotype. We recorded decibels (dB) in our vivarium. The average was 61 dB, but operating the automatic door to the vivarium caused spikes to 95 dB. We modified the door to eliminate noise spikes, which reduced unexpected deaths to 33% in Fmr1 knockout mice raised from birth in this environment (P = 0.07). As the modifications did not eliminate unexpected deaths, we further hypothesized that building vibrations may also be a contributing factor. After installing anti-vibration pads underneath housing carts, unexpected deaths of Fmr1 knockout mice born and raised in this environment decreased to 29% (P < 0.01 compared to the original environment). We also observed significant sex effects, for example, after interventions to reduce sound and vibration, significantly fewer male, but not female, Fmr1 knockout mice died unexpectedly (P < 0.001). The spontaneous seizure phenotype in our Fmr1 knockout mice could serve as a model of seizures observed in individuals with FXS, potentially offering a new translationally-valid phenotype for FXS research. Finally, these observations, although anomalous, serve as a reminder to consider gene-environment interactions when interpreting data derived from Fmr1 knockout mice.
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Affiliation(s)
- Jessica L Armstrong
- Mercer University, College of Pharmacy, Department of Pharmaceutical Sciences, 3001 Mercer University Drive, Atlanta, GA 30341, USA
| | - Tanishka S Saraf
- Mercer University, College of Pharmacy, Department of Pharmaceutical Sciences, 3001 Mercer University Drive, Atlanta, GA 30341, USA
| | - Omkar Bhatavdekar
- Johns Hopkins University, Department of Chemical and Biomolecular Engineering, 3400 North Charles Street, Croft Hall B27, Baltimore, MD 21218, USA
| | - Clinton E Canal
- Mercer University, College of Pharmacy, Department of Pharmaceutical Sciences, 3001 Mercer University Drive, Atlanta, GA 30341, USA.
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16
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Somatostatin-Positive Interneurons Contribute to Seizures in SCN8A Epileptic Encephalopathy. J Neurosci 2021; 41:9257-9273. [PMID: 34544834 DOI: 10.1523/jneurosci.0718-21.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
SCN8A epileptic encephalopathy is a devastating epilepsy syndrome caused by mutant SCN8A, which encodes the voltage-gated sodium channel NaV1.6. To date, it is unclear if and how inhibitory interneurons, which express NaV1.6, influence disease pathology. Using both sexes of a transgenic mouse model of SCN8A epileptic encephalopathy, we found that selective expression of the R1872W SCN8A mutation in somatostatin (SST) interneurons was sufficient to convey susceptibility to audiogenic seizures. Patch-clamp electrophysiology experiments revealed that SST interneurons from mutant mice were hyperexcitable but hypersensitive to action potential failure via depolarization block under normal and seizure-like conditions. Remarkably, GqDREADD-mediated activation of WT SST interneurons resulted in prolonged electrographic seizures and was accompanied by SST hyperexcitability and depolarization block. Aberrantly large persistent sodium currents, a hallmark of SCN8A mutations, were observed and were found to contribute directly to aberrant SST physiology in computational modeling and pharmacological experiments. These novel findings demonstrate a critical and previously unidentified contribution of SST interneurons to seizure generation not only in SCN8A epileptic encephalopathy, but epilepsy in general.SIGNIFICANCE STATEMENT SCN8A epileptic encephalopathy is a devastating neurological disorder that results from de novo mutations in the sodium channel isoform Nav1.6. Inhibitory neurons express NaV1.6, yet their contribution to seizure generation in SCN8A epileptic encephalopathy has not been determined. We show that mice expressing a human-derived SCN8A variant (R1872W) selectively in somatostatin (SST) interneurons have audiogenic seizures. Physiological recordings from SST interneurons show that SCN8A mutations lead to an elevated persistent sodium current which drives initial hyperexcitability, followed by premature action potential failure because of depolarization block. Furthermore, chemogenetic activation of WT SST interneurons leads to audiogenic seizure activity. These findings provide new insight into the importance of SST inhibitory interneurons in seizure initiation, not only in SCN8A epileptic encephalopathy, but for epilepsy broadly.
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Tupal S, Faingold CL. Serotonin 5-HT 4 receptors play a critical role in the action of fenfluramine to block seizure-induced sudden death in a mouse model of SUDEP. Epilepsy Res 2021; 177:106777. [PMID: 34601387 DOI: 10.1016/j.eplepsyres.2021.106777] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 08/25/2021] [Accepted: 09/21/2021] [Indexed: 11/28/2022]
Abstract
RATIONALE Our previous study showed that the recently approved anticonvulsant drug, fenfluramine, which enhances the release of serotonin (5-hydroxytryptamine, 5-HT) in the brain, prevents seizure-induced respiratory arrest (S-IRA) in the DBA/1 mouse model of sudden unexpected death in epilepsy (SUDEP). The present study examined the role of 5-HT receptor subtypes in mediating the effect of this agent by combined administration of fenfluramine with selective 5-HT receptor antagonists prior to seizure in DBA/1 mice. METHODS Fenfluramine (15 mg/kg, i.p.) was administered to primed DBA/1 mice, and audiogenic seizure (Sz) was induced 16 h later. Thirty min prior to Sz induction a selective antagonist acting on 5-HT1A, 5-HT2, 5-HT3 5-HT4, 5-HT5A, 5-HT6 or 5-HT7 receptors at a sub-toxic dose was administered, and changes in seizure-induced behaviors were evaluated. Follow-up studies examined the effect of administration of a 5-HT4 receptor agonist, BIMU 8, as well as the effect of co-administration of ineffective doses of fenfluramine and BIMU-8 on Sz behaviors. RESULTS The 5-HT4 antagonist (GR125487) was the only 5-HT receptor antagonist that was able to reverse the action of fenfluramine to block Sz and S-IRA. Treatment with the 5-HT4 receptor agonist (BIMU-8), or co-administration of ineffective doses of BIMU-8 and fenfluramine significantly reduced the incidence of S-IRA and tonic Sz in DBA/1 mice. The antagonists for 5-HT3, 5-HT5A 5-HT6, and 5-HT7 receptors did not significantly affect the action of fenfluramine. However, the 5-HT1A and the 5-HT2 antagonists enhanced the anticonvulsant effects of fenfluramine. CONCLUSIONS These findings suggest that the action of fenfluramine to prevent seizure-induced sudden death in DBA/1 mice is mediated primarily by activation of 5-HT4 receptors. These studies are the first to indicate the therapeutic potential of 5-HT4 receptor agonists either alone or in combination with fenfluramine for preventing SUDEP. Enhancement of the anticonvulsant effect of fenfluramine by 5-HT1A and 5-HT2 antagonists may involve presynaptic actions of these antagonists. Thus, the Sz and S-IRA blocking actions of fenfluramine involve complex interactions with several 5-HT receptor subtypes. These data also provide further support for the serotonin hypothesis of SUDEP.
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Affiliation(s)
- Srinivasan Tupal
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, USA
| | - Carl L Faingold
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, USA.
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Acute and chronic cardiorespiratory consequences of focal intrahippocampal administration of seizure-inducing agents. Implications for SUDEP. Auton Neurosci 2021; 235:102864. [PMID: 34428716 DOI: 10.1016/j.autneu.2021.102864] [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: 02/19/2021] [Revised: 07/02/2021] [Accepted: 07/26/2021] [Indexed: 11/20/2022]
Abstract
The risk factors for SUDEP are undoubtedly heterogenous but the main factor is the frequency of generalized tonic-clonic seizures with apnoea and/or cardiac abnormalities likely precipitating the lethal event. By its very nature modelling SUDEP experimentally is challenging, yet insights into the nature of the lethal event and precipitating factors are vital in order to understand and prevent fatalities. Acute animal models, which induce status epilepticus (SE), can be used to help understand pathophysiological processes during and following seizures, which sometimes lead to death. The most commonly used method to induce seizures and status epilepticus is systemic administration of an ictogenic agent. Microinjection of such agents into restricted regions within the brain induces a more localised epileptic focus and circumvents the risk of direct actions on cardiorespiratory control centres. Both approaches have revealed substantial cardiovascular and respiratory consequences, including death as a result of apnoea, which may be of central origin, obstructive due to laryngospasm or, at least in genetically modified mice, a result of spreading depolarisation to medullary respiratory control centres. SUDEP is by definition a result of epilepsy, which in turn is diagnosed on the basis of two or more unprovoked seizures. The incidence of tonic-clonic seizures is the main risk factor, raising the possibility that repeated seizures cause cumulative pathological and/or pathophysiological changes that contribute to the risk of SUDEP. Chronic experimental models, which induce repeated seizures that in some cases lead to death, do show progressive development of pathophysiological changes in the myocardium, e.g. prolongation of QT the interval of the ECG or, over longer periods, ventricular hypertrophy. However, the currently available evidence indicates that seizure-related deaths are primarily due to apnoeas, but cardiac factors, particularly cumulative cardiac pathophysiologies due to repeated seizures, are potential contributing factors.
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Yu W, Smolen CE, Hill SF, Meisler MH. Spontaneous seizures and elevated seizure susceptibility in response to somatic mutation of sodium channel Scn8a in the mouse. Hum Mol Genet 2021; 30:902-907. [PMID: 33822038 PMCID: PMC8165645 DOI: 10.1093/hmg/ddab092] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 03/24/2021] [Accepted: 03/29/2021] [Indexed: 02/05/2023] Open
Abstract
De novo mutations of neuronal sodium channels are responsible for ~5% of developmental and epileptic encephalopathies, but the role of somatic mutation of these genes in adult-onset epilepsy is not known. We evaluated the role of post-zygotic somatic mutation by adult activation of a conditional allele of the pathogenic variant Scn8aR1872W in the mouse. After activation of CAG-Cre-ER by tamoxifen, the mutant transcript was expressed throughout the brain at a level proportional to tamoxifen dose. The threshold for generation of spontaneous seizures was reached when the proportion of mutant transcript reached 8% of total Scn8a transcript, equivalent to expression of the epileptogenic variant in 16% of heterozygous neurons. Expression below this level did not result in spontaneous seizures, but did increase susceptibility to seizure induction by kainate or auditory stimulation. The relatively high threshold for spontaneous seizures indicates that somatic mutation of sodium channels is unlikely to contribute to the elevated incidence of epilepsy in the elderly population. However, somatic mutation could increase susceptibility to other seizure stimuli.
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Affiliation(s)
- Wenxi Yu
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109 USA
| | - Corrine E Smolen
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109 USA
| | - Sophie F Hill
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109 USA
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109 USA
| | - Miriam H Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109 USA
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109 USA
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20
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Wenker IC, Teran FA, Wengert ER, Wagley PK, Panchal PS, Blizzard EA, Saraf P, Wagnon JL, Goodkin HP, Meisler MH, Richerson GB, Patel MK. Postictal Death Is Associated with Tonic Phase Apnea in a Mouse Model of Sudden Unexpected Death in Epilepsy. Ann Neurol 2021; 89:1023-1035. [PMID: 33604927 DOI: 10.1002/ana.26053] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 02/17/2021] [Accepted: 02/17/2021] [Indexed: 12/25/2022]
Abstract
OBJECTIVE Sudden unexpected death in epilepsy (SUDEP) is an unpredictable and devastating comorbidity of epilepsy that is believed to be due to cardiorespiratory failure immediately after generalized convulsive seizures. METHODS We performed cardiorespiratory monitoring of seizure-induced death in mice carrying either a p.Arg1872Trp or p.Asn1768Asp mutation in a single Scn8a allele-mutations identified from patients who died from SUDEP-and of seizure-induced death in pentylenetetrazole-treated wild-type mice. RESULTS The primary cause of seizure-induced death for all mice was apnea, as (1) apnea began during a seizure and continued for tens of minutes until terminal asystole, and (2) death was prevented by mechanical ventilation. Fatal seizures always included a tonic phase that was coincident with apnea. This tonic phase apnea was not sufficient to produce death, as it also occurred during many nonfatal seizures; however, all seizures that were fatal had tonic phase apnea. We also made the novel observation that continuous tonic diaphragm contraction occurred during tonic phase apnea, which likely contributes to apnea by preventing exhalation, and this was only fatal when breathing did not resume after the tonic phase ended. Finally, recorded seizures from a patient with developmental epileptic encephalopathy with a previously undocumented SCN8A likely pathogenic variant (p.Leu257Val) revealed similarities to those of the mice, namely, an extended tonic phase that was accompanied by apnea. INTERPRETATION We conclude that apnea coincident with the tonic phase of a seizure, and subsequent failure to resume breathing, are the determining events that cause seizure-induced death in Scn8a mutant mice. ANN NEUROL 2021;89:1023-1035.
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Affiliation(s)
- Ian C Wenker
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA
| | - Frida A Teran
- Department of Neurology, University of Iowa, Iowa City, IA.,Medical Scientist Training Program, University of Iowa, Iowa City, IA.,Iowa Neuroscience Institute, University of Iowa, Iowa City, IA
| | - Eric R Wengert
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA.,Neuroscience Graduate Program, University of Virginia, Charlottesville, VA
| | - Pravin K Wagley
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA.,Department of Neurology, University of Virginia Health System, Charlottesville, VA
| | - Payal S Panchal
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA
| | - Elizabeth A Blizzard
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA
| | - Priyanka Saraf
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA
| | - Jacy L Wagnon
- Department of Human Genetics, University of Michigan, Ann Arbor, MI
| | - Howard P Goodkin
- Department of Neurology, University of Virginia Health System, Charlottesville, VA
| | - Miriam H Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, MI
| | - George B Richerson
- Department of Neurology, University of Iowa, Iowa City, IA.,Iowa Neuroscience Institute, University of Iowa, Iowa City, IA.,Veterans Affairs Medical Center, Iowa City, IA
| | - Manoj K Patel
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA
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21
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Wengert ER, Wenker IC, Wagner EL, Wagley PK, Gaykema RP, Shin JB, Patel MK. Adrenergic Mechanisms of Audiogenic Seizure-Induced Death in a Mouse Model of SCN8A Encephalopathy. Front Neurosci 2021; 15:581048. [PMID: 33762902 PMCID: PMC7982890 DOI: 10.3389/fnins.2021.581048] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 02/10/2021] [Indexed: 12/14/2022] Open
Abstract
Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death amongst patients whose seizures are not adequately controlled by current therapies. Patients with SCN8A encephalopathy have an elevated risk for SUDEP. While transgenic mouse models have provided insight into the molecular mechanisms of SCN8A encephalopathy etiology, our understanding of seizure-induced death has been hampered by the inability to reliably trigger both seizures and seizure-induced death in these mice. Here, we demonstrate that mice harboring an Scn8a allele with the patient-derived mutation N1768D (D/+) are susceptible to audiogenic seizures and seizure-induced death. In adult D/+ mice, audiogenic seizures are non-fatal and have nearly identical behavioral, electrographical, and cardiorespiratory characteristics as spontaneous seizures. In contrast, at postnatal days 20–21, D/+ mice exhibit the same seizure behavior, but have a significantly higher incidence of seizure-induced death following an audiogenic seizure. Seizure-induced death was prevented by either stimulating breathing via mechanical ventilation or by acute activation of adrenergic receptors. Conversely, in adult D/+ mice inhibition of adrenergic receptors converted normally non-fatal audiogenic seizures into fatal seizures. Taken together, our studies show that in our novel audiogenic seizure-induced death model adrenergic receptor activation is necessary and sufficient for recovery of breathing and prevention of seizure-induced death.
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Affiliation(s)
- Eric R Wengert
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, United States.,Neuroscience Graduate Program, University of Virginia Health System, Charlottesville, VA, United States
| | - Ian C Wenker
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, United States
| | - Elizabeth L Wagner
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA, United States.,Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA, United States
| | - Pravin K Wagley
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, United States
| | - Ronald P Gaykema
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, United States
| | - Jung-Bum Shin
- Neuroscience Graduate Program, University of Virginia Health System, Charlottesville, VA, United States.,Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA, United States
| | - Manoj K Patel
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA, United States.,Neuroscience Graduate Program, University of Virginia Health System, Charlottesville, VA, United States
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22
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Purnell BS, Petrucci AN, Li R, Buchanan GF. The effect of time-of-day and circadian phase on vulnerability to seizure-induced death in two mouse models. J Physiol 2021; 599:1885-1899. [PMID: 33501667 DOI: 10.1113/jp280856] [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: 09/23/2020] [Accepted: 01/18/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Sudden unexpected death in epilepsy (SUDEP) is the leading cause of premature death in patients with refractory epilepsy. SUDEP typically occurs during the night, although the reason for this is unclear. We found that, in normally entrained mice, time-of-day alters vulnerability to seizure-induced death. We found that, in free-running mice, circadian phase alters the vulnerability to seizure-induced death. These findings suggest that circadian rhythmicity may be responsible for the increased night-time prevalence of SUDEP ABSTRACT: Sudden unexpected death in epilepsy (SUDEP) is the leading cause of epilepsy-related death. SUDEP typically occurs during the night following a seizure. Many aspects of mammalian physiology are regulated by circadian rhythms in ways that might make seizures occuring during the night more dangerous. Using two mouse models of seizure-induced death, we demonstrate that time-of-day and circadian rhythms alter vulnerability to seizure-induced death. We exposed normally entrained DBA/1 mice to a potentially seizure-inducing acoustic stimulus at different times of day and compared the characteristics and outcomes of the seizures. Time-of-day did not alter the probability of a seizure but it did alter the probability of seizure-induced death. To determine whether circadian rhythms alter vulnerability to seizure-induced death, we induced maximal electroshock seizures in free-running C57BL/6J mice at different circadian time points at the same time as measuring breathing via whole body plethysmography. Circadian phase did not affect seizure severity but it did alter postictal respiratory outcomes and the probability of seizure-induced death. By contrast to our expectations, in entrained and free-running mice, vulnerability to seizure-induced death was greatest during the night and subjective night, respectively. These findings suggest that circadian rhythmicity may be responsible for the increased night-time prevalence of SUDEP and that the underlying mechanism is phase conserved between nocturnal and diurnal mammals. All of the seizures in the present study were induced during wakefulness, indicating that the effect of time point on vulnerability to seizure-induced death was not the result of sleep. Understanding why SUDEP occurs more frequently during the night may inform future preventative countermeasures.
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Affiliation(s)
- Benton S Purnell
- Interdisciplinary Graduate Program in Neuroscience, Iowa City, IA, USA.,Iowa Neuroscience Institute, Iowa City, IA, USA.,Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Alexandra N Petrucci
- Interdisciplinary Graduate Program in Neuroscience, Iowa City, IA, USA.,Iowa Neuroscience Institute, Iowa City, IA, USA.,Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Rui Li
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Gordon F Buchanan
- Interdisciplinary Graduate Program in Neuroscience, Iowa City, IA, USA.,Iowa Neuroscience Institute, Iowa City, IA, USA.,Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
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23
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Koga Y, Tsuchimoto D, Hayashi Y, Abolhassani N, Yoneshima Y, Sakumi K, Nakanishi H, Toyokuni S, Nakabeppu Y. Neural stem cell-specific ITPA deficiency causes neural depolarization and epilepsy. JCI Insight 2020; 5:140229. [PMID: 33208550 PMCID: PMC7710303 DOI: 10.1172/jci.insight.140229] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 10/15/2020] [Indexed: 11/17/2022] Open
Abstract
Inosine triphosphate pyrophosphatase (ITPA) hydrolyzes inosine triphosphate (ITP) and other deaminated purine nucleotides to the corresponding nucleoside monophosphates. In humans, ITPA deficiency causes severe encephalopathy with epileptic seizure, microcephaly, and developmental retardation. In this study, we established neural stem cell-specific Itpa-conditional KO mice (Itpa-cKO mice) to clarify the effects of ITPA deficiency on the neural system. The Itpa-cKO mice showed growth retardation and died within 3 weeks of birth. We did not observe any microcephaly in the Itpa-cKO mice, although the female Itpa-cKO mice did show adrenal hypoplasia. The Itpa-cKO mice showed limb-clasping upon tail suspension and spontaneous and/or audiogenic seizure. Whole-cell patch-clamp recordings from entorhinal cortex neurons in brain slices revealed a depolarized resting membrane potential, increased firing, and frequent spontaneous miniature excitatory postsynaptic current and miniature inhibitory postsynaptic current in the Itpa-cKO mice compared with ITPA-proficient controls. Accumulated ITP or its metabolites, such as cyclic inosine monophosphates, or RNA containing inosines may cause membrane depolarization and hyperexcitability in neurons and induce the phenotype of ITPA-deficient mice, including seizure.
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Affiliation(s)
- Yuichiro Koga
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, and
| | - Daisuke Tsuchimoto
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, and
| | - Yoshinori Hayashi
- Department of Aging Science and Pharmacology, Faculty of Dental Sciences, Kyushu University, Fukuoka, Japan
- Department of Physiology, Nihon University School of Dentistry, Tokyo, Japan
| | - Nona Abolhassani
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, and
| | - Yasuto Yoneshima
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, and
| | - Kunihiko Sakumi
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, and
| | - Hiroshi Nakanishi
- Department of Pharmacology, Faculty of Pharmacy, Yasuda Women’s University, Hiroshima, Japan
| | - Shinya Toyokuni
- Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yusaku Nakabeppu
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, and
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