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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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Nishiguchi T, Shibata K, Yamanishi K, Dittrich MN, Islam NY, Patel S, Phuong NJ, Marra PS, Malicoat JR, Seki T, Nishizawa Y, Yamanashi T, Iwata M, Shinozaki G. The Bispectral Electroencephalography Method Quantifies Postoperative Delirium-Like States in Young and Aged Male Mice After Head-Mount Implantation Surgery. J Gerontol A Biol Sci Med Sci 2024; 79:glae158. [PMID: 38877811 PMCID: PMC11272051 DOI: 10.1093/gerona/glae158] [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: 01/08/2024] [Indexed: 06/16/2024] Open
Abstract
Delirium, a syndrome characterized by an acute change in attention, awareness, and cognition, is commonly observed in older adults, although there are few quantitative monitoring methods in the clinical setting. We developed a bispectral electroencephalography (BSEEG) method capable of detecting delirium and can quantify the severity of delirium using a novel algorithm. Preclinical application of this novel BSEEG method can capture a delirium-like state in mice following lipopolysaccharide administration. However, its application to postoperative delirium (POD) has not yet been validated in animal experiments. This study aimed to create a POD model in mice with the BSEEG method by monitoring BSEEG scores following EEG head-mount implantation surgery and throughout the recovery. We compared the BSEEG scores of C57BL/6J young (2-3 months old) with aged (18-19 months old) male mice for quantitative evaluation of POD-like states. Postoperatively, both groups displayed increased BSEEG scores and a loss of regular diurnal changes in BSEEG scores. In young mice, BSEEG scores and regular diurnal changes recovered relatively quickly to baseline by postoperative day (PO-Day) 3. Conversely, aged mice exhibited prolonged increases in postoperative BSEEG scores and it reached steady states only after PO-Day 8. This study suggests that the BSEEG method can be utilized as a quantitative measure of POD and assess the effect of aging on recovery from POD in the preclinical model.
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Affiliation(s)
- Tsuyoshi Nishiguchi
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, California, USA
- Faculty of Medicine, Department of Neuropsychiatry, Tottori University, Yonago, Tottori, Japan
| | - Kazuki Shibata
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, California, USA
- Sumitomo Pharma Co. Ltd., Osaka, Osaka, Japan
| | - Kyosuke Yamanishi
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, California, USA
- Department of Neuropsychiatry, School of Medicine, Hyogo Medical University, Nishinomiya, Hyogo, Japan
| | - Mia Nicole Dittrich
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, California, USA
| | - Noah Yuki Islam
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, California, USA
| | - Shivani Patel
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
| | - Nathan James Phuong
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, California, USA
| | - Pedro S Marra
- Department of Psychiatry, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Johnny R Malicoat
- Department of Psychiatry, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Tomoteru Seki
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, California, USA
- Department of Psychiatry, Tokyo Medical University, Shinjuku-ku, Tokyo, Japan
| | - Yoshitaka Nishizawa
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, California, USA
- Faculty of Medicine, Department of Neuropsychiatry, Osaka Medical and Pharmaceutical University, Takatsuki, Osaka, Japan
| | - Takehiko Yamanashi
- Faculty of Medicine, Department of Neuropsychiatry, Tottori University, Yonago, Tottori, Japan
| | - Masaaki Iwata
- Faculty of Medicine, Department of Neuropsychiatry, Tottori University, Yonago, Tottori, Japan
| | - Gen Shinozaki
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, California, USA
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Petrucci AN, Jones AR, Kreitlow BL, Buchanan GF. Peri-ictal activation of dorsomedial dorsal raphe serotonin neurons reduces mortality associated with maximal electroshock seizures. Brain Commun 2024; 6:fcae052. [PMID: 38487550 PMCID: PMC10939444 DOI: 10.1093/braincomms/fcae052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 12/13/2023] [Accepted: 03/08/2024] [Indexed: 03/17/2024] Open
Abstract
Over one-third of patients with epilepsy will develop refractory epilepsy and continue to experience seizures despite medical treatment. These patients are at the greatest risk for sudden unexpected death in epilepsy. The precise mechanisms underlying sudden unexpected death in epilepsy are unknown, but cardiorespiratory dysfunction and arousal impairment have been implicated. Substantial circumstantial evidence suggests serotonin is relevant to sudden unexpected death in epilepsy as it modulates sleep/wake regulation, breathing and arousal. The dorsal raphe nucleus is a major serotonergic center and a component of the ascending arousal system. Seizures disrupt the firing of dorsal raphe neurons, which may contribute to reduced responsiveness. However, the relevance of the dorsal raphe nucleus and its subnuclei to sudden unexpected death in epilepsy remains unclear. The dorsomedial dorsal raphe may be a salient target due to its role in stress and its connections with structures implicated in sudden unexpected death in epilepsy. We hypothesized that optogenetic activation of dorsomedial dorsal raphe serotonin neurons in TPH2-ChR2-YFP (n = 26) mice and wild-type (n = 27) littermates before induction of a maximal electroshock seizure would reduce mortality. In this study, pre-seizure activation of dorsal raphe nucleus serotonin neurons reduced mortality in TPH2-ChR2-YFP mice with implants aimed at the dorsomedial dorsal raphe. These results implicate the dorsomedial dorsal raphe in this novel circuit influencing seizure-induced mortality. It is our hope that these results and future experiments will define circuit mechanisms that could ultimately reduce sudden unexpected death in epilepsy.
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Affiliation(s)
- Alexandra N Petrucci
- Interdisciplinary Graduate Program in Neuroscience, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Allysa R Jones
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Benjamin L Kreitlow
- Interdisciplinary Graduate Program in Neuroscience, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Gordon F Buchanan
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, 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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Villacres JE, Riveira N, Kim S, Colgin LL, Noebels JL, Lopez AY. Abnormal patterns of sleep and waking behaviors are accompanied by neocortical oscillation disturbances in an Ank3 mouse model of epilepsy-bipolar disorder comorbidity. Transl Psychiatry 2023; 13:403. [PMID: 38123552 PMCID: PMC10733341 DOI: 10.1038/s41398-023-02700-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 11/28/2023] [Accepted: 12/04/2023] [Indexed: 12/23/2023] Open
Abstract
ANK3 is a leading bipolar disorder (BD) candidate gene in humans and provides a unique opportunity for studying epilepsy-BD comorbidity. Previous studies showed that deletion of Ank3-1b, a BD-associated variant of Ank3 in mice leads to increased firing threshold and diminished action potential dynamic range of parvalbumin (PV) interneurons and absence epilepsy, thus providing a biological mechanism linking epilepsy and BD. To explore the behavioral overlap of these disorders, we characterized behavioral patterns of Ank3-1b KO mice during overnight home-cage activity and examined network activity during these behaviors using paired video and EEG recordings. Since PV interneurons contribute to the generation of high-frequency gamma oscillations, we anticipated changes in the power of neocortical EEG signals in the gamma frequency range (> 25 Hz) during behavioral states related to human BD symptoms, including abnormal sleep, hyperactivity, and repetitive behaviors. Ank3-1b KO mice exhibited an overall increase in slow gamma (~25-45 Hz) power compared to controls, and slow gamma power correlated with seizure phenotype severity across behaviors. During sleep, increased slow gamma power correlated with decreased time spent in the rapid eye movement (REM) stage of sleep. Seizures were more common during REM sleep compared to non-REM (NREM) sleep. We also found that Ank3-1b KO mice were hyperactive and exhibited a repetitive behavior phenotype that co-occurred with increased slow gamma power. Our results identify a novel EEG biomarker associating Ank3 genetic variation with BD and epilepsy and suggest modulation of gamma oscillations as a potential therapeutic target.
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Affiliation(s)
- Juan E Villacres
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX, 78712-0805, USA
- Department of Neuroscience, The University of Texas at Austin, Austin, TX, 78712-0805, USA
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, 78712-0805, USA
| | - Nicholas Riveira
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX, 78712-0805, USA
- Department of Neuroscience, The University of Texas at Austin, Austin, TX, 78712-0805, USA
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, 78712-0805, USA
| | - Sohmee Kim
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX, 78712-0805, USA
- Department of Neuroscience, The University of Texas at Austin, Austin, TX, 78712-0805, USA
| | - Laura L Colgin
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX, 78712-0805, USA
- Department of Neuroscience, The University of Texas at Austin, Austin, TX, 78712-0805, USA
- Institute for Neuroscience, The University of Texas at Austin, Austin, TX, 78712-0805, USA
| | - Jeffrey L Noebels
- Department of Neurology, Baylor College of Medicine, Houston, TX, 77030, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Angel Y Lopez
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX, 78712-0805, USA.
- Department of Neuroscience, The University of Texas at Austin, Austin, TX, 78712-0805, USA.
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Sainju RK, Dragon DN, Winnike HB, Vilella L, Li X, Lhatoo S, Eyck PT, Wendt LH, Richerson GB, Gehlbach BK. Interictal respiratory variability predicts severity of hypoxemia after generalized convulsive seizures. Epilepsia 2023; 64:2373-2384. [PMID: 37344924 PMCID: PMC10538446 DOI: 10.1111/epi.17691] [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: 04/05/2023] [Revised: 06/19/2023] [Accepted: 06/19/2023] [Indexed: 06/23/2023]
Abstract
OBJECTIVE Severe respiratory dysfunction induced by generalized convulsive seizures (GCS) is now thought to be a common mechanism for sudden unexpected death in epilepsy (SUDEP). In a mouse model of seizure-induced death, increased interictal respiratory variability was reported in mice that later died of respiratory arrest after GCS. We studied respiratory variability in epilepsy patients as a predictive tool for severity of postictal hypoxemia, a potential biomarker for SUDEP risk. We then explored the relationship between respiratory variability and central CO2 drive, measured by the hypercapnic ventilatory response (HCVR). METHODS We reviewed clinical, video-electroencephalography, and respiratory (belts, airflow, pulse oximeter, and HCVR) data of epilepsy patients. Mean, SD, and coefficient of variation (CV) of interbreath interval (IBI) were calculated. Primary outcomes were: (1) nadir of capillary oxygen saturation (SpO2 ) and (2) duration of oxygen desaturation. Poincaré plots of IBI were created. Covariates were evaluated in univariate models, then, based on Akaike information criteria (AIC), multivariate regression models were created. RESULTS Of 66 GCS recorded in 131 subjects, 30 had interpretable respiratory data. In the multivariate model with the lowest AIC value, duration of epilepsy was a significant predictor of duration of oxygen desaturation. Duration of tonic phase and CV of IBI during the third postictal minute correlated with SpO2 nadir, whereas CV of IBI during non-rapid eye movement sleep had a negative correlation. Poincaré plots showed that long-term variability was significantly greater in subjects with ≥200 s of postictal oxygen desaturation after GCS compared to those with <200 s desaturation. Finally, HCVR slope showed a negative correlation with measures of respiratory variability. SIGNIFICANCE These results indicate that interictal respiratory variability predicts severity of postictal oxygen desaturation, suggesting its utility as a potential biomarker. They also suggest that interictal respiratory control may be abnormal in some patients with epilepsy.
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Affiliation(s)
- Rup K. Sainju
- Department of Neurology University of Iowa Hospitals and Clinics, Iowa City, IA
| | - Deidre N. Dragon
- Department of Neurology University of Iowa Hospitals and Clinics, Iowa City, IA
| | - Harold B. Winnike
- Institute for Clinical and Translational Science University of Iowa, Iowa City, IA
| | - Laura Vilella
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX
| | - Xiaojin Li
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX
| | - Samden Lhatoo
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX
| | - Patrick Ten Eyck
- Institute for Clinical and Translational Science University of Iowa, Iowa City, IA
| | - Linder H Wendt
- Institute for Clinical and Translational Science University of Iowa, Iowa City, IA
| | - George B. Richerson
- Department of Neurology University of Iowa Hospitals and Clinics, Iowa City, IA
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA
- Iowa Neuroscience Institute, University of Iowa, IA
- VA Medical Center, Iowa City, IA
| | - Brian K. Gehlbach
- Department of Internal Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA
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Abstract
PURPOSE OF REVIEW Sudden unexpected death in epilepsy (SUDEP) is a leading cause of death in patients with epilepsy. This review highlights the recent literature regarding epidemiology on a global scale, putative mechanisms and thoughts towards intervention and prevention. RECENT FINDINGS Recently, numerous population-based studies have examined the incidence of SUDEP in many countries. Remarkably, incidence is quite consistent across these studies, and is commensurate with the recent estimates of about 1.2 per 1000 patient years. These studies further continue to support that incidence is similar across the ages and that comparable factors portend heightened risk for SUDEP. Fervent research in patients and animal studies continues to hone the understanding of potential mechanisms for SUDEP, especially those regarding seizure-induced respiratory dysregulation. Many of these studies and others have begun to lay out a path towards identification of improved treatment and prevention means. However, continued efforts are needed to educate medical professionals about SUDEP risk and the need to disclose this to patients. SUMMARY SUDEP is a devastating potential outcome of epilepsy. More is continually learned about risk and mechanisms from clinical and preclinical studies. This knowledge can hopefully be leveraged into preventive measures in the near future.
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Affiliation(s)
- Gordon F Buchanan
- Department of Neurology
- Neuroscience Graduate Program
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Ana T Novella Maciel
- Department of Neurology
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Universidad Nacional Autónoma de México, Mexico City, México
| | - Matthew J Summerfield
- Neuroscience Graduate Program
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
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George AG, Farrell JS, Colangeli R, Wall AK, Gom RC, Kesler MT, Rodriguez de la Hoz C, Villa BR, Perera T, Rho JM, Kurrasch D, Teskey GC. Sudden unexpected death in epilepsy is prevented by blocking postictal hypoxia. Neuropharmacology 2023; 231:109513. [PMID: 36948357 DOI: 10.1016/j.neuropharm.2023.109513] [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: 10/19/2022] [Revised: 02/21/2023] [Accepted: 03/18/2023] [Indexed: 03/24/2023]
Abstract
Epilepsy is at times a fatal disease. Sudden unexpected death in epilepsy (SUDEP) is the leading cause of epilepsy-related mortality in people with intractable epilepsy and is defined by exclusion; non-accidental, non-toxicologic, and non-anatomic causes of death. While SUDEP often follows a bilateral tonic-clonic seizure, the mechanisms that ultimately lead to terminal apnea and then asystole remain elusive and there is a lack of preventative treatments. Based on the observation that discrete seizures lead to local and postictal vasoconstriction, resulting in hypoperfusion, hypoxia and behavioural disturbances in the forebrain we reasoned those similar mechanisms may play a role in SUDEP when seizures invade the brainstem. Here we tested this neurovascular-based hypothesis of SUDEP in awake non-anesthetized mice by pharmacologically preventing seizure-induced vasoconstriction, with cyclooxygenase-2 or L-type calcium channel antagonists. In both acute and chronic mouse models of seizure-induced premature mortality, ibuprofen and nicardipine extended life while systemic drug levels remained high enough to be effective. We also examined the potential role of spreading depolarization in the acute model of seizure-induced premature mortality. These data provide a proof-of-principle for the neurovascular hypothesis of SUDEP rather than spreading depolarization and the use of currently available drugs to prevent it.
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Affiliation(s)
- Antis G George
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada
| | - Jordan S Farrell
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Neurosurgery, Stanford University, Palo Alto, CA, 94305, USA
| | - Roberto Colangeli
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada; Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Marche Polytechnic University, Ancona, Italy
| | - Alexandra K Wall
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada
| | - Renaud C Gom
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada
| | - Mitchell T Kesler
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
| | | | - Bianca R Villa
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada
| | - Tefani Perera
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada
| | - Jong M Rho
- Department of Pediatrics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; Department of Neurosciences, Pediatrics and Pharmacology, University of California, San Diego and Rady Children's Hospital, San Diego, CA, USA
| | - Deborah Kurrasch
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Medical Genetics, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - G Campbell Teskey
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
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Kim DS, Pessah IN, Santana CM, Purnell BS, Li R, Buchanan GF, Rumbeiha WK. Investigations into hydrogen sulfide-induced suppression of neuronal activity in vivo and calcium dysregulation in vitro. Toxicol Sci 2023; 192:kfad022. [PMID: 36882182 PMCID: PMC10109532 DOI: 10.1093/toxsci/kfad022] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023] Open
Abstract
Acute exposure to high concentrations of hydrogen sulfide (H2S) leads to sudden death and, if survived, lingering neurological disorders. Clinical signs include seizures, loss of consciousness, and dyspnea. The proximate mechanisms underlying H2S-induced acute toxicity and death have not been clearly elucidated. We investigated electrocerebral, cardiac and respiratory activity during H2S exposure using electroencephalogram (EEG), electrocardiogram (EKG) and plethysmography. H2S suppressed electrocerebral activity and disrupted breathing. Cardiac activity was comparatively less affected. To test whether Ca2+ dysregulation contributes to H2S-induced EEG suppression, we developed an in vitro real-time rapid throughput assay measuring patterns of spontaneous synchronized Ca2+ oscillations in cultured primary cortical neuronal networks loaded with the indicator Fluo-4 using the fluorescent imaging plate reader (FLIPR-Tetra®). Sulfide >5 ppm dysregulated synchronous calcium oscillation (SCO) patterns in a dose-dependent manner. Inhibitors of NMDA and AMPA receptors magnified H2S-induced SCO suppression. Inhibitors of L-type voltage gated Ca2+ channels and transient receptor potential channels prevented H2S-induced SCO suppression. Inhibitors of T-type voltage gated Ca2+ channels, ryanodine receptors, and sodium channels had no measurable influence on H2S-induced SCO suppression. Exposures to > 5 ppm sulfide also suppressed neuronal electrical activity in primary cortical neurons measured by multi-electrode array (MEA), an effect alleviated by pretreatment with the nonselective transient receptor potential channel inhibitor, 2-APB. 2-APB also reduced primary cortical neuronal cell death from sulfide exposure. These results improve our understanding of the role of different Ca2+ channels in acute H2S-induced neurotoxicity and identify transient receptor potential channel modulators as novel structures with potential therapeutic benefits.
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Affiliation(s)
- Dong-Suk Kim
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, California 95616, USA
| | - Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, California 95616, USA
| | - Cristina M Santana
- VDPAM, College of Veterinary Medicine, Iowa State University, Ames, Iowa 50011, USA
- MRIGlobal, Kansas City, Missouri 64110, USA
| | - Benton S Purnell
- Department of Neurology, Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52246, USA
- Department of Nerosurgery, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Rui Li
- Department of Neurology, Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52246, USA
| | - Gordon F Buchanan
- Department of Neurology, Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52246, USA
| | - Wilson K Rumbeiha
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, California 95616, USA
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10
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Joyal KG, Petrucci AN, Littlepage-Saunders MV, Boodhoo NA, Wendt LH, Buchanan GF. Selective Serotonin Reuptake Inhibitors and 5-HT 2 Receptor Agonists Have Distinct, Sleep-state Dependent Effects on Postictal Breathing in Amygdala Kindled Mice. Neuroscience 2023; 513:76-95. [PMID: 36702372 PMCID: PMC9974756 DOI: 10.1016/j.neuroscience.2023.01.016] [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: 08/24/2022] [Revised: 01/11/2023] [Accepted: 01/16/2023] [Indexed: 01/24/2023]
Abstract
Seizures can cause profound breathing disruptions. Seizures arising from sleep cause greater breathing impairment than those emerging from wakefulness and more often result in sudden unexpected death in epilepsy (SUDEP). The neurotransmitter serotonin (5-HT) plays a major role in respiration and sleep-wake regulation. 5-HT modulates seizure susceptibility and severity and is dysregulated by seizures. Thus, the impact of seizures on breathing dysregulation may be due to impaired 5-HT neurotransmission. We examined whether pharmacologically increasing 5-HT neurotransmission prior to seizures improves postictal breathing and how sleep-state during seizure induction contributes to these effects. We assessed breathing with whole-body plethysmography in 84 amygdala-kindled mice pre-treated with selective serotonin reuptake inhibitors (SSRI) or 5-HT2 receptor agonists. SSRIs and 5-HT2 agonists increased postictal breathing frequency (fR), tidal volume (VT), and minute ventilation (VE) at different timepoints following seizures induced during wakefulness. These effects were not observed following seizures induced during NREM sleep. SSRIs suppressed ictal and postictal apnea regardless of sleep state. The SSRI citalopram and the 5-HT2 agonists TCB-2 and MK-212 decreased breathing variability following wake-occurring seizures at different postictal timepoints. Only MK-212 decreased breathing variability when seizures were induced during NREM sleep. The 5-HT2A antagonist MDL-11939 reduced the effect of citalopram on fR, VT, and VE, and enhanced its effect on breathing variability in the initial period following a seizure. These results suggest that 5-HT mechanisms that are dependent on or independent from the 5-HT2 family of receptors impact breathing on different timescales during the recovery of eupnea, and that certain serotonergic treatments may be less effective at facilitating postictal breathing following seizures emerging from sleep.
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Affiliation(s)
- Katelyn G Joyal
- Interdisciplinary Graduate Program in Neuroscience, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
| | - Alexandra N Petrucci
- Interdisciplinary Graduate Program in Neuroscience, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
| | - Mydirah V Littlepage-Saunders
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
| | - Nicole A Boodhoo
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
| | - Linder H Wendt
- Institute for Clinical and Translational Science, University of Iowa, Iowa City, IA 52242, USA.
| | - Gordon F Buchanan
- Interdisciplinary Graduate Program in Neuroscience, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
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11
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Purnell BS, Braun A, Fedele D, Murugan M, Boison D. Diaphragmatic pacing for the prevention of sudden unexpected death in epilepsy. Brain Commun 2022; 4:fcac232. [PMID: 36196086 PMCID: PMC9525001 DOI: 10.1093/braincomms/fcac232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/18/2022] [Accepted: 09/15/2022] [Indexed: 01/19/2023] Open
Abstract
Sudden unexpected death in epilepsy is the leading cause of epilepsy related death. Currently, there are no reliable methods for preventing sudden unexpected death in epilepsy. The precise pathophysiology of sudden unexpected death in epilepsy is unclear; however, convergent lines of evidence suggest that seizure-induced respiratory arrest plays a central role. It is generally agreed that sudden unexpected death in epilepsy could be averted if the patient could be rapidly ventilated following the seizure. The diaphragm is a muscle in the chest which contracts to draw air into the lungs. Diaphragmatic pacing is a surgical intervention which facilitates normal ventilation in situations, such as spinal cord injury and sleep apnoea, in which endogenous respiration would be inadequate or non-existent. In diaphragmatic pacing, electrodes are implanted directly onto diaphragm or adjacent to the phrenic nerves which innervate the diaphragm. These electrodes are then rhythmically stimulated, thereby eliciting contractions of the diaphragm which emulate endogenous breathing. The goal of this study was to test the hypothesis that seizure-induced respiratory arrest and death can be prevented with diaphragmatic pacing. Our approach was to induce respiratory arrest using maximal electroshock seizures in adult, male, C57BL6 mice outfitted with EEG and diaphragmatic electrodes (n = 8 mice). In the experimental group, the diaphragm was stimulated to exogenously induce breathing. In the control group, no stimulation was applied. Breathing and cortical electrographic activity were monitored using whole body plethysmography and EEG, respectively. A majority of the animals that did not receive the diaphragmatic pacing intervention died of seizure-induced respiratory arrest. Conversely, none of the animals that received the diaphragmatic pacing intervention died. Diaphragmatic pacing improved postictal respiratory outcomes (two-way ANOVA, P < 0.001) and reduced the likelyhood of seizure-induced death (Fisher's exact test, P = 0.026). Unexpectedly, diaphragmatic pacing did not instantly restore breathing during the postictal period, potentially indicating peripheral airway occlusion by laryngospasm. All diaphragmatically paced animals breathed at some point during the pacing stimulation. Two animals took their first breath prior to the onset of pacing and some animals had significant apnoeas after the pacing stimulation. Sudden unexpected death in epilepsy results in more years of potential life lost than any other neurological condition with the exception of stroke. By demonstrating that seizure-induced respiratory arrest can be prevented by transient diaphragmatic pacing in animal models we hope to inform the development of closed-loop systems capable of detecting and preventing sudden unexpected death in epilepsy.
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Affiliation(s)
- Benton S Purnell
- Department of Neurosurgery, Robert Wood Johnson Medical School, Rutgers University, 10 Plum St., New Brunswick, NJ 08901, USA
| | - Alexander Braun
- Department of Neurosurgery, Robert Wood Johnson Medical School, Rutgers University, 10 Plum St., New Brunswick, NJ 08901, USA
| | - Denise Fedele
- Department of Neurosurgery, Robert Wood Johnson Medical School, Rutgers University, 10 Plum St., New Brunswick, NJ 08901, USA
| | - Madhuvika Murugan
- Department of Neurosurgery, Robert Wood Johnson Medical School, Rutgers University, 10 Plum St., New Brunswick, NJ 08901, USA
| | - Detlev Boison
- Department of Neurosurgery, Robert Wood Johnson Medical School, Rutgers University, 10 Plum St., New Brunswick, NJ 08901, USA
- Brain Health Institute, Rutgers University, 683 Hoes Lane West, Piscataway, NJ 08854, USA
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12
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Kreitlow BL, Li W, Buchanan GF. Chronobiology of epilepsy and sudden unexpected death in epilepsy. Front Neurosci 2022; 16:936104. [PMID: 36161152 PMCID: PMC9490261 DOI: 10.3389/fnins.2022.936104] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 06/27/2022] [Indexed: 11/24/2022] Open
Abstract
Epilepsy is a neurological disease characterized by spontaneous, unprovoked seizures. Various insults render the brain hyperexcitable and susceptible to seizure. Despite there being dozens of preventative anti-seizure medications available, these drugs fail to control seizures in nearly 1 in 3 patients with epilepsy. Over the last century, a large body of evidence has demonstrated that internal and external rhythms can modify seizure phenotypes. Physiologically relevant rhythms with shorter periodic rhythms, such as endogenous circadian rhythms and sleep-state, as well as rhythms with longer periodicity, including multidien rhythms and menses, influence the timing of seizures through poorly understood mechanisms. The purpose of this review is to discuss the findings from both human and animal studies that consider the effect of such biologically relevant rhythms on epilepsy and seizure-associated death. Patients with medically refractory epilepsy are at increased risk of sudden unexpected death in epilepsy (SUDEP). The role that some of these rhythms play in the nocturnal susceptibility to SUDEP will also be discussed. While the involvement of some of these rhythms in epilepsy has been known for over a century, applying the rhythmic nature of such phenomenon to epilepsy management, particularly in mitigating the risk of SUDEP, has been underutilized. As our understanding of the physiological influence on such rhythmic phenomenon improves, and as technology for chronic intracranial epileptiform monitoring becomes more widespread, smaller and less invasive, novel seizure-prediction technologies and time-dependent chronotherapeutic seizure management strategies can be realized.
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Affiliation(s)
- Benjamin L. Kreitlow
- Medical Scientist Training Program, University of Iowa, Iowa City, IA, United States
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA, United States
- Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, United States
- Department of Neurology, University of Iowa, Iowa City, IA, United States
- Carver College of Medicine, University of Iowa, Iowa City, IA, United States
| | - William Li
- Department of Neurology, University of Iowa, Iowa City, IA, United States
- Carver College of Medicine, University of Iowa, Iowa City, IA, United States
| | - Gordon F. Buchanan
- Medical Scientist Training Program, University of Iowa, Iowa City, IA, United States
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA, United States
- Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, United States
- Department of Neurology, University of Iowa, Iowa City, IA, United States
- Carver College of Medicine, University of Iowa, Iowa City, IA, United States
- *Correspondence: Gordon F. Buchanan, ; orcid.org/0000-0003-2371-4455
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13
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Joyal KG, Kreitlow BL, Buchanan GF. The role of sleep state and time of day in modulating breathing in epilepsy: implications for sudden unexpected death in epilepsy. Front Neural Circuits 2022; 16:983211. [PMID: 36082111 PMCID: PMC9445500 DOI: 10.3389/fncir.2022.983211] [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: 06/30/2022] [Accepted: 07/25/2022] [Indexed: 11/13/2022] Open
Abstract
Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death among patients with refractory epilepsy. While the exact etiology of SUDEP is unknown, mounting evidence implicates respiratory dysfunction as a precipitating factor in cases of seizure-induced death. Dysregulation of breathing can occur in epilepsy patients during and after seizures as well as interictally, with many epilepsy patients exhibiting sleep-disordered breathing (SDB), such as obstructive sleep apnea (OSA). The majority of SUDEP cases occur during the night, with the victim found prone in or near a bed. As breathing is modulated in both a time-of-day and sleep state-dependent manner, it is relevant to examine the added burden of nocturnal seizures on respiratory function. This review explores the current state of understanding of the relationship between respiratory function, sleep state and time of day, and epilepsy. We highlight sleep as a particularly vulnerable period for individuals with epilepsy and press that this topic warrants further investigation in order to develop therapeutic interventions to mitigate the risk of SUDEP.
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Affiliation(s)
- Katelyn G. Joyal
- Interdisciplinary Graduate Program in Neuroscience, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
| | - Benjamin L. Kreitlow
- Interdisciplinary Graduate Program in Neuroscience, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
- Medical Scientist Training Program, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
| | - Gordon F. Buchanan
- Interdisciplinary Graduate Program in Neuroscience, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
- Medical Scientist Training Program, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
- *Correspondence: Gordon F. Buchanan
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14
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Collard R, Aziz MC, Rapp K, Cutshall C, Duyvesteyn E, Metcalf CS. Galanin analogs prevent mortality from seizure-induced respiratory arrest in mice. Front Neural Circuits 2022; 16:901334. [PMID: 36051473 PMCID: PMC9425456 DOI: 10.3389/fncir.2022.901334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 07/28/2022] [Indexed: 11/13/2022] Open
Abstract
ObjectiveSudden Unexpected Death in Epilepsy (SUDEP) accounts for 20% of mortality in those with recurrent seizures. While risk factors, monitoring systems, and standard practices are in place, the pathophysiology of SUDEP is still not well understood. Better knowledge of SUDEP and its potential mechanisms of action is crucial to reducing risk in this patient population and developing potential treatment options. Clinical studies and animal models of SUDEP suggest that diminished post-ictal respiratory control may be the dominant mechanism contributing to mortality. Recently, it was demonstrated that the depletion of the neuropeptide galanin in the amygdala occurs in human SUDEP. The amygdala plays a key role in the central integration of respiratory signaling; the depletion of galanin may represent a critical change that predisposes individuals to SUDEP.Materials and methodsTo evaluate the impact of enhancing galaninergic signaling to potentially protect against SUDEP, we studied seizure-induced respiratory arrest (S-IRA) following central (intracerebroventricular, intra-amygdala) and systemic (intraperitoneal, subcutaneous) administration of galanin analogs. Seizure naïve and seizure experienced (fully kindled) mice were tested.ResultsCentral and systemically administered galanin analogs protect against S-IRA in naïve C57Bl/6J mice. Differential efficacy between receptor subtype-selective analogs varied based on the route of administration. Sub-chronic systemic administration at doses that reduced 6 Hz seizures also protected against S-IRA. Acute treatment benefits also extended to fully kindled mice experiencing tonic extension.SignificanceThese data demonstrate that galanin analogs may be protective against post-ictal respiratory collapse.
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Affiliation(s)
- Ryley Collard
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, United States
| | - Miriam C. Aziz
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, United States
| | - Kevin Rapp
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, United States
| | - Connor Cutshall
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, United States
| | - Evalien Duyvesteyn
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, United States
| | - Cameron S. Metcalf
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, United States
- Epilepsy Therapy Screening Program Contract Site, Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT, United States
- *Correspondence: Cameron S. Metcalf,
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15
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Buchanan GF, Gluckman BJ, Kalume FK, Lhatoo S, Maganti RK, Noebels JL, Simeone KA, Quigg MS, Pavlova MK. Proceedings of the Sleep and Epilepsy Workshop: Section 3 Mortality: Sleep, Night, and SUDEP. Epilepsy Curr 2021; 21:15357597211004556. [PMID: 33787378 PMCID: PMC8609595 DOI: 10.1177/15357597211004556] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death in patients with refractory epilepsy. Likely pathophysiological mechanisms include seizure-induced cardiac and respiratory dysregulation. A frequently identified feature in SUDEP cases is that they occur at night. This raises the question of a role for sleep state in regulating of SUDEP. An association with sleep has been identified in a number of studies with patients and in animal models. The focus of this section of the Sleep and Epilepsy Workshop was on identifying and understanding the role for sleep and time of day in the pathophysiology of SUDEP.
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Affiliation(s)
- Gordon F. Buchanan
- Department of Neurology and Iowa Neuroscience Institute, University of Iowa Carver College of Medicine, Iowa City, IA, USA
- Department of Neurology, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, USA
| | - Bruce J. Gluckman
- Department of Engineering Science & Mechanics, Penn State University, University Park, PA, USA
- Department of Neurosurgery, Penn State University, University Park, PA, USA
- Department of Biomedical Engineering, Penn State University, University Park, PA, USA
| | - Franck K. Kalume
- Department of Neurological Surgery, University of Washington and Seattle Children’s Research Institute, Seattle, WA, USA
| | - Samden Lhatoo
- Department of Neurology, University of Texas McGovern Medical School, Houston, TX, USA
| | - Rama K. Maganti
- Department of Neurology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Jeffrey L. Noebels
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Kristina A. Simeone
- Department of Pharmacology & Neuroscience, Creighton University School of Medicine, Omaha, NE, USA
| | - Mark S. Quigg
- Department of Neurology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Milena K. Pavlova
- Department of Neurology, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, USA
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16
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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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17
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Bispectral EEG (BSEEG) quantifying neuro-inflammation in mice induced by systemic inflammation: A potential mouse model of delirium. J Psychiatr Res 2021; 133:205-211. [PMID: 33360427 DOI: 10.1016/j.jpsychires.2020.12.036] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 12/03/2020] [Accepted: 12/09/2020] [Indexed: 02/06/2023]
Abstract
Most of the animal studies using inflammation-induced cognitive change have relied on behavioral testing without objective and biologically solid methods to quantify the severity of cognitive disturbances. We have developed a bispectral EEG (BSEEG) method using a novel algorithm in clinical study. This method effectively differentiates between patients with and without delirium, and predict long-term mortality. In the present study, we aimed to apply our bispectral EEG (BSEEG) method, which can detect patients with delirium, to a mouse model of delirium with systemic inflammation induced by lipopolysaccharides (LPS) injection. We recorded EEG after LPS injection using wildtype early adulthood mice (2~3-month-old) and aged mice (18-19-month-old). Animal EEG recordings were converted for power spectral density to calculate BSEEG score using the similar BSEEG algorithm previously developed for our human study. The BSEEG score was relatively stable and slightly high during the day. Alternatively, the BSEEG score was erratic and low in average during the night. LPS injection increased the BSEEG score dose-dependently and diminished the diurnal changes. The mean BSEEG score increased much more in the aged mice group as dosage increased. Our results suggest that BSEEG method can objectively "quantify" level of neuro-Inflammation induced by systemic inflammation (LPS), and that this BSEEG method can be useful as a model of delirium in mice.
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18
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Petrucci AN, Joyal KG, Chou JW, Li R, Vencer KM, Buchanan GF. Post-ictal Generalized EEG Suppression is reduced by Enhancing Dorsal Raphe Serotonergic Neurotransmission. Neuroscience 2020; 453:206-221. [PMID: 33242541 DOI: 10.1016/j.neuroscience.2020.11.029] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 11/14/2020] [Accepted: 11/16/2020] [Indexed: 01/02/2023]
Abstract
Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death in patients with refractory epilepsy. A proposed risk marker for SUDEP is the duration of post-ictal generalized EEG suppression (PGES). The mechanisms underlying PGES are unknown. Serotonin (5-HT) has been implicated in SUDEP pathophysiology. Seizures suppress activity of 5-HT neurons in the dorsal raphe nucleus (DRN). We hypothesized that suppression of DRN 5-HT neuron activity contributes to PGES and increasing 5-HT neurotransmission or stimulating the DRN before a seizure would decrease PGES duration. Adult C57BL/6J and Pet1-Cre mice received EEG/EMG electrodes, a bipolar stimulating/recording electrode in the right basolateral amygdala, and either a microdialysis guide cannula or an injection of adeno-associated virus (AAV) allowing expression of channelrhodopsin2 plus an optic fiber into the DRN. Systemic application of the selective 5-HT reuptake inhibitor citalopram (20 mg/kg) decreased PGES duration from seizures induced during wake (n = 23) and non-rapid eye movement (NREM) sleep (n = 13) whereas fluoxetine (10 mg/kg) pretreatment decreased PGES duration following seizures induced from wake (n = 11), but not NREM sleep (n = 9). Focal chemical (n = 6) or optogenetic (n = 8) stimulation of the DRN reduced PGES duration following seizures in kindled mice induced during wake. During PGES, animals exhibited immobility and suppression of EEG activity that was reduced by citalopram pretreatment. These results suggest 5-HT and the DRN may regulate PGES.
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Affiliation(s)
- Alexandra N Petrucci
- Interdisciplinary Graduate Program in Neuroscience, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States; Department of Neurology, Carver College of Medicine, Carver College of Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States; Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States.
| | - Katelyn G Joyal
- Interdisciplinary Graduate Program in Neuroscience, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States; Department of Neurology, Carver College of Medicine, Carver College of Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States; Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States.
| | - Jonathan W Chou
- Department of Neurology, Carver College of Medicine, Carver College of Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States; Department of Health and Human Physiology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, IA 52242, United States.
| | - Rui Li
- Department of Neurology, Carver College of Medicine, Carver College of Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States; Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States.
| | - Kimberly M Vencer
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States; Department of Health and Human Physiology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, IA 52242, United States
| | - Gordon F Buchanan
- Interdisciplinary Graduate Program in Neuroscience, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States; Department of Neurology, Carver College of Medicine, Carver College of Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States; Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States.
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19
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Purnell BS, Buchanan GF. Free-running circadian breathing rhythms are eliminated by suprachiasmatic nucleus lesion. J Appl Physiol (1985) 2020; 129:49-57. [PMID: 32501775 PMCID: PMC7469233 DOI: 10.1152/japplphysiol.00211.2020] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 05/06/2020] [Accepted: 06/02/2020] [Indexed: 11/22/2022] Open
Abstract
It is widely agreed that breathing is subject to circadian regulation. Circadian differences in respiratory physiology significantly impact a number of diseases including sleep apnea, asthma, and seizure-induced death. The effect of time of day on breathing has been previously characterized; however, an endogenous free-running respiratory rhythm in mammals has not previously been described. Furthermore, it is assumed that circadian rhythms in breathing are dependent on the hypothalamic suprachiasmatic nucleus (SCN), the home of the mammalian central circadian oscillator, but this has not been shown experimentally. The breathing of mice was monitored during wakefulness using whole body plethysmography at six times of day while housed under light-dark conditions and at six circadian phases while housed under constant darkness. Respiratory frequency and minute ventilation, but not tidal volume, were significantly higher during the active phase in both entrained and free-running conditions. To determine whether circadian regulation of breathing requires the SCN, in separate sets of animals this structure was electrolytically lesioned bilaterally or a sham surgery was performed, and breathing was measured at six different time points. Time-dependent oscillations in breathing were lost in SCN-lesioned animals, but not those subjected to sham surgery. These results suggest that breathing is subject to circadian regulation via the SCN. Mechanistic insights into the circadian regulation of breathing may lead to targeted interventions to reduce the morbidity and mortality associated with diseases with respiratory pathophysiology.NEW & NOTEWORTHY It has long been appreciated that breathing is altered by time of day. This study demonstrates that rhythmicity in breathing persists in constant darkness but is dependent on the suprachiasmatic nucleus in the hypothalamus. Understanding circadian rhythms in breathing may be important for the treatment and prevention of diseases such as sleep apnea and sudden unexpected death in epilepsy.
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Affiliation(s)
- Benton S Purnell
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, Iowa
- Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Gordon F Buchanan
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, Iowa
- Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, Iowa
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20
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Petrucci AN, Joyal KG, Purnell BS, Buchanan GF. Serotonin and sudden unexpected death in epilepsy. Exp Neurol 2020; 325:113145. [PMID: 31866464 PMCID: PMC7029792 DOI: 10.1016/j.expneurol.2019.113145] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 11/12/2019] [Accepted: 12/10/2019] [Indexed: 12/20/2022]
Abstract
Epilepsy is a highly prevalent disease characterized by recurrent, spontaneous seizures. Approximately one-third of epilepsy patients will not achieve seizure freedom with medical management and become refractory to conventional treatments. These patients are at greatest risk for sudden unexpected death in epilepsy (SUDEP). The exact etiology of SUDEP is unknown, but a combination of respiratory, cardiac, neuronal electrographic dysfunction, and arousal impairment is thought to underlie SUDEP. Serotonin (5-HT) is involved in regulation of breathing, sleep/wake states, arousal, and seizure modulation and has been implicated in the pathophysiology of SUDEP. This review explores the current state of understanding of the relationship between 5-HT, epilepsy, and respiratory and autonomic control processes relevant to SUDEP in epilepsy patients and in animal models.
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Affiliation(s)
- Alexandra N Petrucci
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA 52242, United States of America; Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States of America
| | - Katelyn G Joyal
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA 52242, United States of America; Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States of America
| | - Benton S Purnell
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA 52242, United States of America; Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States of America
| | - Gordon F Buchanan
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA 52242, United States of America; Department of Neurology, University of Iowa, Iowa City, IA 52242, United States of America; Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States of America.
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21
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Li R, Buchanan GF. Scurrying to Understand Sudden Expected Death in Epilepsy: Insights From Animal Models. Epilepsy Curr 2019; 19:390-396. [PMID: 31526023 PMCID: PMC6891182 DOI: 10.1177/1535759719874787] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death in patients with refractory epilepsy, accounting for up to 17% of deaths in patients with epilepsy. The pathophysiology of SUDEP has remained unclear, largely because it is unpredictable and commonly unwitnessed. This poses a great challenge to studies in patients. Recently, there has been an increase in animal studies to try to better understand the pathophysiology of SUDEP. In this current review, we focus on developments through seizure-induced death models and the preventative strategies they may reveal.
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Affiliation(s)
- Rui Li
- Department of Neurology, Carver College of Medicine, University of Iowa, IA, USA
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, IA, USA
| | - Gordon F. Buchanan
- Department of Neurology, Carver College of Medicine, University of Iowa, IA, USA
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, IA, USA
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22
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Teran FA, Kim Y, Crotts MS, Bravo E, Emaus KJ, Richerson GB. Time of Day and a Ketogenic Diet Influence Susceptibility to SUDEP in Scn1a R1407X/+ Mice. Front Neurol 2019; 10:278. [PMID: 30984098 PMCID: PMC6449461 DOI: 10.3389/fneur.2019.00278] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 03/04/2019] [Indexed: 01/02/2023] Open
Abstract
Sudden unexpected death in epilepsy (SUDEP) is a major cause of mortality in patients with drug-resistant epilepsy. Most SUDEP cases occur in bed at night and are preceded by a generalized tonic-clonic seizure (GTCS). Dravet syndrome (DS) is a severe childhood-onset epilepsy commonly caused by mutations in the SCN1A gene. Affected individuals suffer from refractory seizures and an increased risk of SUDEP. Here, we demonstrate that mice with the Scn1aR1407X/+ loss-of-function mutation (DS) experience more spontaneous seizures and SUDEP during the early night. We also evaluate effects of long-term ketogenic diet (KD) treatment on mortality and seizure frequency. DS mice showed high premature mortality (44% survival by P60) that was associated with increased spontaneous GTCSs 1–2 days prior to SUDEP. KD treated mice had a significant reduction in mortality (86% survival by P60) compared to mice fed a control diet. Interestingly, increased survival was not associated with a decrease in seizure frequency. Further studies are needed to determine how KD confers protection from SUDEP. Moreover, our findings implicate time of day as a factor influencing the occurrence of seizures and SUDEP. DS mice, though nocturnal, are more likely to have SUDEP at night, suggesting that the increased incidence of SUDEP at night in may not be solely due to sleep.
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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.,Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, United States
| | - YuJaung Kim
- Department of Neurology, University of Iowa, Iowa City, IA, United States.,Department of Biomedical Engineering, University of Iowa, Iowa City, IA, United States
| | - Megan S Crotts
- Department of Neurology, University of Iowa, Iowa City, IA, United States
| | - Eduardo Bravo
- Department of Neurology, University of Iowa, Iowa City, IA, United States.,Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, United States
| | - Katlynn J Emaus
- 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.,Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, United States.,Department of Molecular Physiology & Biophysics, University of Iowa, Iowa City, IA, United States.,Neurology, Veterans Affairs Medical Center, Iowa City, IA, United States
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23
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Kruse SW, Dayton KG, Purnell BS, Rosner JI, Buchanan GF. Effect of monoamine reuptake inhibition and α 1 blockade on respiratory arrest and death following electroshock-induced seizures in mice. Epilepsia 2019; 60:495-507. [PMID: 30723893 PMCID: PMC6467066 DOI: 10.1111/epi.14652] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Revised: 12/26/2018] [Accepted: 01/03/2019] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death in patients with refractory epilepsy. Although the mechanisms for SUDEP are incompletely understood, seizure-induced respiratory arrest (S-IRA) has been strongly and consistently implicated. A body of evidence indicates that serotonin (5-HT), a modulator of breathing, plays a critical role in SUDEP. Because the 5-HT and norepinephrine (NE) systems interact in many biologic processes and NE is known to modulate breathing and seizures, we hypothesized that NE may play a role in S-IRA and SUDEP. METHODS We examined the effects of pharmacologic manipulation of 5-HT and NE on S-IRA and death following maximal electroshock (MES)-induced seizures in adult wild-type (WT) mice, genetically 5-HT neuron-deficient (Lmx1bf/f/p ) mice, and chemically NE neuron-deficient mice. Mice were treated with pharmacologic agents targeting the serotonergic and noradrenergic systems and subjected to seizure induction via MES while breathing was measured via whole-body plethysmography. RESULTS S-IRA and death was reduced in WT mice with NE reuptake inhibitors (NRIs), reboxetine and atomoxetine, selective serotonin reuptake inhibitors (SSRIs), fluoxetine and citalopram, and the dual 5-HT/NE reuptake inhibitor (SNRI), duloxetine. S-IRA and death was also reduced in Lmx1bf/f/p mice with reboxetine and fluoxetine. The protective effects of the reuptake inhibitors were prevented by the α1 antagonist, prazosin. Citalopram did not reduce S-IRA and death in NE neuron-deficient mice. SIGNIFICANCE These data suggest that 5-HT and NE critically interact in the modulation of breathing following a seizure and potentially inform preventive strategies for SUDEP.
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Affiliation(s)
- Stephen W. Kruse
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242
- Iowa Neuroscience Institute, University of Iowa, Iowa City, IA 52242
| | - Kyle G. Dayton
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA 52242
- Iowa Neuroscience Institute, University of Iowa, Iowa City, IA 52242
| | - Benton S. Purnell
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA 52242
- Iowa Neuroscience Institute, University of Iowa, Iowa City, IA 52242
| | - Jared I. Rosner
- Secondary Student Training Program, University of Iowa, Iowa City, IA 52242
| | - Gordon F. Buchanan
- Department of Neurology, University of Iowa, Iowa City, IA 52242
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA 52242
- Iowa Neuroscience Institute, University of Iowa, Iowa City, IA 52242
- Carver College of Medicine, University of Iowa, Iowa City, IA 52242
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24
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Purnell BS, Thijs RD, Buchanan GF. Dead in the Night: Sleep-Wake and Time-Of-Day Influences on Sudden Unexpected Death in Epilepsy. Front Neurol 2018; 9:1079. [PMID: 30619039 PMCID: PMC6297781 DOI: 10.3389/fneur.2018.01079] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 11/27/2018] [Indexed: 11/13/2022] Open
Abstract
Sudden unexpected death in epilepsy (SUDEP) is the leading cause of epilepsy-related death in patients with refractory epilepsy. Convergent lines of evidence suggest that SUDEP occurs due to seizure induced perturbation of respiratory, cardiac, and electrocerebral function as well as potential predisposing factors. It is consistently observed that SUDEP happens more during the night and the early hours of the morning. The aim of this review is to discuss evidence from patient cases, clinical studies, and animal research which is pertinent to the nocturnality of SUDEP. There are a number of factors which might contribute to the nighttime predilection of SUDEP. These factors fall into four categories: influences of (1) being unwitnessed, (2) lying prone in bed, (3) sleep-wake state, and (4) circadian rhythms. During the night, seizures are more likely to be unwitnessed; therefore, it is less likely that another person would be able to administer a lifesaving intervention. Patients are more likely to be prone on a bed following a nocturnal seizure. Being prone in the accouterments of a bed during the postictal period might impair breathing and increase SUDEP risk. Sleep typically happens at night and seizures which emerge from sleep might be more dangerous. Lastly, there are circadian changes to physiology during the night which might facilitate SUDEP. These possible explanations for the nocturnality of SUDEP are not mutually exclusive. The increased rate of SUDEP during the night is likely multifactorial involving both situational factors, such as being without a witness and prone, and physiological changes due to the influence of sleep and circadian rhythms. Understanding the causal elements in the nocturnality of SUDEP may be critical to the development of effective preventive countermeasures.
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Affiliation(s)
- Benton S Purnell
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA, United States.,Neuroscience Program, University of Iowa, Iowa City, IA, United States.,Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
| | - Roland D Thijs
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, Netherlands.,NIHR University College London Hospitals Biomedical Research Centre, UCL Institute of Neurology, London, United Kingdom.,Department of Neurology, LUMC Leiden University Medical Center, Leiden, Netherlands
| | - Gordon F Buchanan
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA, United States.,Neuroscience Program, University of Iowa, Iowa City, IA, United States.,Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
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25
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Dorsal Raphe Serotonin Neurons Mediate CO 2-Induced Arousal from Sleep. J Neurosci 2018; 38:1915-1925. [PMID: 29378860 DOI: 10.1523/jneurosci.2182-17.2018] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 01/07/2018] [Accepted: 01/10/2018] [Indexed: 01/10/2023] Open
Abstract
Arousal from sleep in response to CO2 is a critical protective phenomenon. Dysregulation of CO2-induced arousal contributes to morbidity and mortality from prevalent diseases, such as obstructive sleep apnea and sudden infant death syndrome. Despite the critical nature of this protective reflex, the precise mechanism for CO2-induced arousal is unknown. Because CO2 is a major regulator of breathing, prevailing theories suggest that activation of respiratory chemo- and mechano-sensors is required for CO2-induced arousal. However, populations of neurons that are not involved in the regulation of breathing are also chemosensitive. Among these are serotonin (5-HT) neurons in the dorsal raphe nucleus (DRN) that comprise a component of the ascending arousal system. We hypothesized that direct stimulation of these neurons with CO2 could cause arousal from sleep independently of enhancing breathing. Dialysis of CO2-rich acidified solution into DRN, but not medullary raphe responsible for modulating breathing, caused arousal from sleep. Arousal was lost in mice with a genetic absence of 5-HT neurons, and with acute pharmacological or optogenetic inactivation of DRN 5-HT neurons. Here we demonstrate that CO2 can cause arousal from sleep directly, without requiring enhancement of breathing, and that chemosensitive 5-HT neurons in the DRN critically mediate this arousal. Better understanding mechanisms underlying this protective reflex may lead to interventions to reduce disease-associated morbidity and mortality.SIGNIFICANCE STATEMENT Although CO2-induced arousal is critical to a number of diseases, the specific mechanism is not well understood. We previously demonstrated that serotonin (5-HT) neurons are important for CO2-induced arousal, as mice without 5-HT neurons do not arouse to CO2 Many have interpreted this to mean that medullary 5-HT neurons that regulate breathing are important in this arousal mechanism. Here we found that direct application of CO2-rich aCSF to the dorsal raphe nucleus, but not the medullary raphe, causes arousal from sleep, and that this arousal was lost with genetic ablation or acute inhibition of 5-HT neurons. We propose that 5-HT neurons in the dorsal raphe nucleus can be activated directly by CO2 to cause arousal independently of respiratory activation.
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