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Kessi M, Peng J, Duan H, He H, Chen B, Xiong J, Wang Y, Yang L, Wang G, Kiprotich K, Bamgbade OA, He F, Yin F. The Contribution of HCN Channelopathies in Different Epileptic Syndromes, Mechanisms, Modulators, and Potential Treatment Targets: A Systematic Review. Front Mol Neurosci 2022; 15:807202. [PMID: 35663267 PMCID: PMC9161305 DOI: 10.3389/fnmol.2022.807202] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 04/06/2022] [Indexed: 12/04/2022] Open
Abstract
Background Hyperpolarization-activated cyclic nucleotide-gated (HCN) current reduces dendritic summation, suppresses dendritic calcium spikes, and enables inhibitory GABA-mediated postsynaptic potentials, thereby suppressing epilepsy. However, it is unclear whether increased HCN current can produce epilepsy. We hypothesized that gain-of-function (GOF) and loss-of-function (LOF) variants of HCN channel genes may cause epilepsy. Objectives This systematic review aims to summarize the role of HCN channelopathies in epilepsy, update genetic findings in patients, create genotype–phenotype correlations, and discuss animal models, GOF and LOF mechanisms, and potential treatment targets. Methods The review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, for all years until August 2021. Results We identified pathogenic variants of HCN1 (n = 24), HCN2 (n = 8), HCN3 (n = 2), and HCN4 (n = 6) that were associated with epilepsy in 74 cases (43 HCN1, 20 HCN2, 2 HCN3, and 9 HCN4). Epilepsy was associated with GOF and LOF variants, and the mechanisms were indeterminate. Less than half of the cases became seizure-free and some developed drug-resistant epilepsy. Of the 74 cases, 12 (16.2%) died, comprising HCN1 (n = 4), HCN2 (n = 2), HCN3 (n = 2), and HCN4 (n = 4). Of the deceased cases, 10 (83%) had a sudden unexpected death in epilepsy (SUDEP) and 2 (16.7%) due to cardiopulmonary failure. SUDEP affected more adults (n = 10) than children (n = 2). HCN1 variants p.M234R, p.C329S, p.V414M, p.M153I, and p.M305L, as well as HCN2 variants p.S632W and delPPP (p.719–721), were associated with different phenotypes. HCN1 p.L157V and HCN4 p.R550C were associated with genetic generalized epilepsy. There are several HCN animal models, pharmacological targets, and modulators, but precise drugs have not been developed. Currently, there are no HCN channel openers. Conclusion We recommend clinicians to include HCN genes in epilepsy gene panels. Researchers should explore the possible underlying mechanisms for GOF and LOF variants by identifying the specific neuronal subtypes and neuroanatomical locations of each identified pathogenic variant. Researchers should identify specific HCN channel openers and blockers with high binding affinity. Such information will give clarity to the involvement of HCN channelopathies in epilepsy and provide the opportunity to develop targeted treatments.
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Affiliation(s)
- Miriam Kessi
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
- Department of Pediatrics, Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Jing Peng
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Haolin Duan
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Hailan He
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Baiyu Chen
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Juan Xiong
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Ying Wang
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Lifen Yang
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Guoli Wang
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Karlmax Kiprotich
- Department of Epidemiology and Medical Statistics, School of Public Health, Moi University, Eldoret, Kenya
| | - Olumuyiwa A. Bamgbade
- Department of Anesthesiology and Pharmacology, University of British Columbia, Vancouver, BC, Canada
| | - Fang He
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Fei Yin
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
- *Correspondence: Fei Yin
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Cheah CS, Beckman MA, Catterall WA, Oakley JC. Sharp-Wave Ripple Frequency and Interictal Epileptic Discharges Increase in Tandem During Thermal Induction of Seizures in a Mouse Model of Genetic Epilepsy. Front Cell Neurosci 2021; 15:751762. [PMID: 34733140 PMCID: PMC8558377 DOI: 10.3389/fncel.2021.751762] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 09/28/2021] [Indexed: 11/13/2022] Open
Abstract
Dravet Syndrome (DS) is a genetic, infantile-onset epilepsy with refractory seizures and severe cognitive impairment. While network level pathophysiology is poorly understood, work in genetic mouse models of DS reveals selective reduction of inhibitory interneuron excitability, a likely mechanism of seizures and comorbidities. Consistent with the critical role of interneurons in timing and recruitment of network activity, hippocampal sharp wave ripples (SPW-R)—interneuron dependent compound brain rhythms essential for spatial learning and memory—are less frequent and ripple frequency is slower in DS mice, both likely to impair cognitive performance. Febrile seizures are characteristic of DS, reflecting a temperature-dependent shift in excitation–inhibition balance. DS interneurons are sensitive to depolarization block and may fall silent with increased excitation precipitating epileptic transformation of ripples. To determine the temperature dependence of SWP-R features and relationship of SPW-R to hippocampal interictal activity, we recorded hippocampal local field potentials in a DS mouse model and wildtype littermate controls while increasing core body temperature. In both genotypes, temperature elevation speeds ripple frequency, although DS ripples remain consistently slower. The rate of SPW-R also increases in both genotypes but subsequently falls in DS mice as interictal epileptic activity simultaneously increases preceding a thermally-evoked seizure. Epileptic events occur intermixed with SPW-R, some during SPW-R burst complexes, and transiently suppress SPW-R occurrence suggesting shared network elements. Together these data demonstrate a temperature dependence of SPW-R rate and ripple frequency and suggest a pathophysiologic mechanism by which elevated temperature transforms a normal brain rhythm into epileptic event.
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Affiliation(s)
- Christine S Cheah
- Department of Neurology, University of Washington, Seattle, WA, United States
| | - Megan A Beckman
- Department of Pharmacology, University of Washington, Seattle, WA, United States
| | - William A Catterall
- Department of Pharmacology, University of Washington, Seattle, WA, United States
| | - John C Oakley
- Department of Neurology, University of Washington, Seattle, WA, United States.,Department of Pharmacology, University of Washington, Seattle, WA, United States
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3
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Bongioanni P, Del Carratore R, Corbianco S, Diana A, Cavallini G, Masciandaro SM, Dini M, Buizza R. Climate change and neurodegenerative diseases. ENVIRONMENTAL RESEARCH 2021; 201:111511. [PMID: 34126048 DOI: 10.1016/j.envres.2021.111511] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 05/25/2021] [Accepted: 06/08/2021] [Indexed: 06/12/2023]
Abstract
The climate change induced global warming, and in particular the increased frequency and intensity of heat waves, have been linked to health problems. Among them, scientific works have been reporting an increased incidence of neurological diseases, encompassing also neurodegenerative ones, such as Dementia of Alzheimer's type, Parkinson's Disease, and Motor Neuron Diseases. Although the increase in prevalence of neurodegenerative diseases is well documented by literature reports, the link between global warming and the enhanced prevalence of such diseases remains elusive. This is the main theme of our work, which aims to examine the connection between high temperature exposure and neurodegenerative diseases. Firstly, we evaluate the influence of high temperatures exposure on the pathophysiology of these disorders. Secondly, we discuss its effects on the thermoregulation, already compromised in affected patients, and its interference with processes of excitotoxicity, oxidative stress and neuroinflammation, all of them related with neurodegeneration. Finally, we investigate chronic versus acute stressors on body warming, and put forward a possible interpretation of the beneficial or detrimental effects on the brain, which is responsible for the incidence or progression of neurological disorders.
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Affiliation(s)
- Paolo Bongioanni
- Severe Acquired Brain Injuries Dpt Section, Azienda Ospedaliero-Universitaria Pisana, Pisa, Italy; NeuroCare Onlus, Pisa, Italy
| | | | - Silvia Corbianco
- Interdepartmental Research Centre on Biology and Pathology of Aging, University of Pisa, Italy; Human Movement and Rehabilitation Research Laboratory, Pisa, Italy
| | - Andrea Diana
- Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy
| | - Gabriella Cavallini
- Interdepartmental Research Centre on Biology and Pathology of Aging, University of Pisa, Italy
| | - Silvia M Masciandaro
- NeuroCare Onlus, Pisa, Italy; Institute of Clinical Physiology, National Research Council, Pisa, Italy
| | - Marco Dini
- Interdepartmental Research Centre on Biology and Pathology of Aging, University of Pisa, Italy; Human Movement and Rehabilitation Research Laboratory, Pisa, Italy
| | - Roberto Buizza
- Scuola Superiore Sant'Anna and Centre for Climate Change Studies and Sustainable Actions (3CSA), Pisa, Italy
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4
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Mosili P, Maikoo S, Mabandla MV, Qulu L. The Pathogenesis of Fever-Induced Febrile Seizures and Its Current State. Neurosci Insights 2020; 15:2633105520956973. [PMID: 33225279 PMCID: PMC7649866 DOI: 10.1177/2633105520956973] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 08/18/2020] [Indexed: 12/13/2022] Open
Abstract
Febrile seizures, commonly in children between the ages of 3 months to 5 years, are a neurological abnormality characterized by neuronal hyper-excitability, that occur as a result of an increased core body temperature during a fever, which was caused by an underlying systemic infection. Such infections cause the immune system to elicit an inflammatory response resulting in the release of cytokines from macrophages. The cytokines such as interleukin (IL)- 1β, IL-6, and tumour necrosis factor-α (TNF-α) combat the infection in the localized area ultimately spilling over into circulation resulting in elevated cytokine levels. The cytokines, along with pathogen-associated molecular patterns (PAMPs) expressed on pathogens for example, lipopolysaccharide (LPS), interact with the blood brain barrier (BBB) causing a ‘leaky’ BBB which facilitates cytokines and LPS entry into the central nervous system. The cytokines activate the microglia which release their own cytokines, specifically IL1β. IL-β interacts with the brain endothelium resulting in the activation of cyclooxygenase 2 which catalyzes the production of prostaglandin 2 (PGE2). PGE2 enters the hypothalamic region and induces a fever. Abnormally increased IL-1β levels also progressively increases excitatory (glutamatergic) neurotransmission, and decreases inhibitory (GABAergic) neurotransmission, thus mediating the pathogenesis of convulsions. Current treatments for febrile seizures present with side effects that are detrimental to health, which fosters the need for an alternative, more affordable treatment with fewer adverse side effects, and 1 that is easily accessible, especially in low income areas that are also affected by other underlying socio-economic factors, in which febrile seizures are of growing concern.
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Affiliation(s)
- Palesa Mosili
- University of KwaZulu-Natal College of Health Sciences, Durban, KwaZulu-Natal, South Africa
| | - Shreyal Maikoo
- University of KwaZulu-Natal, Durban, KwaZulu-Natal, South Africa
| | | | - Lihle Qulu
- University of KwaZulu-Natal College of Health Sciences, Durban, KwaZulu-Natal, South Africa
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5
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Nomura S, Kida H, Hirayama Y, Imoto H, Inoue T, Moriyama H, Mitsushima D, Suzuki M. Reduction of spike generation frequency by cooling in brain slices from rats and from patients with epilepsy. J Cereb Blood Flow Metab 2019; 39:2286-2294. [PMID: 30117752 PMCID: PMC6827110 DOI: 10.1177/0271678x18795365] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
This study aimed to understand the mechanism by which brain cooling terminates epileptic discharge. Cortical slices were prepared from rat brains (n = 19) and samples from patients with intractable epilepsy that had undergone temporal lobectomy (n = 7). We performed whole cell current clamp recordings at approximately physiological brain temperature (35℃) and at cooler temperatures (25℃ and 15℃). The firing threshold in human neurons was lower at 25℃ (-32.6 mV) than at 35℃ (-27.0 mV). The resting potential and spike frequency were similar at 25℃ and 35℃. Cooling from 25℃ to 15℃ did not change the firing threshold, but the resting potential increased from -65.5 to -54.0 mV and the waveform broadened from 1.85 to 6.55 ms, due to delayed repolarization. These changes enhanced the initial spike appearance and reduced spike frequency; moreover, spike frequency was insensitive to increased levels of current injections. Similar results were obtained in rat brain studies. We concluded that the reduction in spike frequency at 15℃, due to delayed repolarization, might be a key mechanism by which brain cooling terminates epileptic discharge. On the other hand, spike frequency was not influenced by the reduced firing threshold or the elevated resting potential caused by cooling.
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Affiliation(s)
- Sadahiro Nomura
- Department of Neurosurgery, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan.,Epilepsy Center, Yamaguchi University Hospital, Yamaguchi, Japan
| | - Hiroyuki Kida
- Department of Physiology, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
| | - Yuya Hirayama
- Department of Neurosurgery, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
| | - Hirochika Imoto
- Department of Neurosurgery, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan.,Epilepsy Center, Yamaguchi University Hospital, Yamaguchi, Japan
| | - Takao Inoue
- Department of Neurosurgery, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
| | - Hiroshi Moriyama
- Department of Neurosurgery, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
| | - Dai Mitsushima
- Department of Physiology, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
| | - Michiyasu Suzuki
- Department of Neurosurgery, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
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6
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Ruszkiewicz JA, Tinkov AA, Skalny AV, Siokas V, Dardiotis E, Tsatsakis A, Bowman AB, da Rocha JBT, Aschner M. Brain diseases in changing climate. ENVIRONMENTAL RESEARCH 2019; 177:108637. [PMID: 31416010 PMCID: PMC6717544 DOI: 10.1016/j.envres.2019.108637] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 08/06/2019] [Accepted: 08/07/2019] [Indexed: 05/12/2023]
Abstract
Climate change is one of the biggest and most urgent challenges for the 21st century. Rising average temperatures and ocean levels, altered precipitation patterns and increased occurrence of extreme weather events affect not only the global landscape and ecosystem, but also human health. Multiple environmental factors influence the onset and severity of human diseases and changing climate may have a great impact on these factors. Climate shifts disrupt the quantity and quality of water, increase environmental pollution, change the distribution of pathogens and severely impacts food production - all of which are important regarding public health. This paper focuses on brain health and provides an overview of climate change impacts on risk factors specific to brain diseases and disorders. We also discuss emerging hazards in brain health due to mitigation and adaptation strategies in response to climate changes.
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Affiliation(s)
- Joanna A Ruszkiewicz
- Molecular Toxicology Group, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Alexey A Tinkov
- Yaroslavl State University, Yaroslavl, Russia; IM Sechenov First Moscow State Medical University, Moscow, Russia; Institute of Cellular and Intracellular Symbiosis, Russian Academy of Sciences, Orenburg, Russia
| | - Anatoly V Skalny
- Yaroslavl State University, Yaroslavl, Russia; IM Sechenov First Moscow State Medical University, Moscow, Russia; Trace Element Institute for UNESCO, Lyon, France
| | - Vasileios Siokas
- Department of Neurology, Laboratory of Neurogenetics, University of Thessaly, University Hospital of Larissa, Larissa, Greece
| | - Efthimios Dardiotis
- Department of Neurology, Laboratory of Neurogenetics, University of Thessaly, University Hospital of Larissa, Larissa, Greece
| | - Aristidis Tsatsakis
- Laboratory of Toxicology, School of Medicine, University of Crete, 71003, Heraklion, Greece
| | - Aaron B Bowman
- School of Health Sciences, Purdue University, West Lafayette, IN, United States
| | - João B T da Rocha
- Department of Biochemistry, Federal University of Santa Maria, Santa Maria, Brazil
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, United States.
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7
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Raveau M, Shimohata A, Amano K, Miyamoto H, Yamakawa K. DYRK1A-haploinsufficiency in mice causes autistic-like features and febrile seizures. Neurobiol Dis 2018; 110:180-191. [PMID: 29223763 DOI: 10.1016/j.nbd.2017.12.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 11/28/2017] [Accepted: 12/05/2017] [Indexed: 11/28/2022] Open
Abstract
Mutations and copy number variants affecting DYRK1A gene encoding the dual-specificity tyrosine phosphorylation-regulated kinase 1A are among the most frequent genetic causes of neurodevelopmental disorders including autism spectrum disorder (ASD) associated with microcephaly, febrile seizures and severe speech acquisition delay. Here we developed a mouse model harboring a frame-shift mutation in Dyrk1a resulting in a protein truncation and elimination of its kinase activity site. Dyrk1a+/- mice showed significant impairments in cognition and cognitive flexibility, communicative ultrasonic vocalizations, and social contacts. Susceptibility to hyperthermia-induced seizures was also significantly increased in these mice. The truncation leading to haploinsufficiency of DYRK1A in mice thus recapitulates the syndromic phenotypes observed in human patients and constitutes a useful model for further investigations of the mechanisms leading to ASD, speech delay and febrile seizures.
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Affiliation(s)
- Matthieu Raveau
- Laboratory for Neurogenetics, RIKEN Brain Science Institute, Saitama 351-0198, Japan
| | - Atsushi Shimohata
- Laboratory for Neurogenetics, RIKEN Brain Science Institute, Saitama 351-0198, Japan
| | - Kenji Amano
- Laboratory for Neurogenetics, RIKEN Brain Science Institute, Saitama 351-0198, Japan
| | - Hiroyuki Miyamoto
- Laboratory for Neurogenetics, RIKEN Brain Science Institute, Saitama 351-0198, Japan
| | - Kazuhiro Yamakawa
- Laboratory for Neurogenetics, RIKEN Brain Science Institute, Saitama 351-0198, Japan.
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8
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Yu F, Xu J, Xiao Z, Peng B, He X. Endoplasmic reticulum retention of KCNQ2 potassium channel mutants following temperature elevation. Biomed Mater Eng 2017; 28:S243-S253. [PMID: 28372301 DOI: 10.3233/bme-171647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND KCNQ2 plays a key role in the regulation of neuronal excitability. The R214W and Y284C mutants of KCNQ2 channels, which are associated with BFNC, can decrease channel function to cause neuronal hyperexcitability and promote seizures. Previous studies revealed that elevated temperature caused up-regulation of KCNQ2 expression. OBJECTIVE The present study sought to investigate the impact of temperature elevation on neuronal KCNQ2 ion channel mutants. METHODS Protein expression of wt KCNQ2 and the R214W, Y284C and truncated selective filter mutants at different temperatures was detected by live-cell confocal fluorescence microscopy and by Western blotting. Whole-cell patch clamp was performed to record the effect of temperature on the electrophysiological activity of KCNQ2 channels. RESULTS Temperature elevation caused an unexpected increase in voltage-dependent KCNQ2 channel activation but also increased the endoplasmic reticulum (ER) retention of KCNQ2 protein, and the ER retention was greater for mutants associated with BFNC than for wt KCNQ2. Temperature elevation did not increase the fluorescence intensity of cells transfected with a truncated selective filter mutant. CONCLUSIONS The direct effect of heat on KCNQ2 channels may be involved in excitability regulation of neurons, and the P-loop region is critical for temperature-dependent modulation of the expression and trafficking of KCNQ2 channels.
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Affiliation(s)
- Fang Yu
- Department of Pathology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Jian Xu
- Weifang Maternity and Child Hospital, Weifang, China
| | - Zheman Xiao
- Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan University, Wuhan, China
| | - Biwen Peng
- Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan University, Wuhan, China
| | - Xiaohua He
- Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan University, Wuhan, China
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9
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Dutton SBB, Dutt K, Papale LA, Helmers S, Goldin AL, Escayg A. Early-life febrile seizures worsen adult phenotypes in Scn1a mutants. Exp Neurol 2017; 293:159-171. [PMID: 28373025 DOI: 10.1016/j.expneurol.2017.03.026] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 02/17/2017] [Accepted: 03/22/2017] [Indexed: 01/27/2023]
Abstract
Mutations in the voltage-gated sodium channel (VGSC) gene SCN1A, encoding the Nav1.1 channel, are responsible for a number of epilepsy disorders including genetic epilepsy with febrile seizures plus (GEFS+) and Dravet syndrome (DS). Patients with SCN1A mutations often experience prolonged early-life febrile seizures (FSs), raising the possibility that these events may influence epileptogenesis and lead to more severe adult phenotypes. To test this hypothesis, we subjected 21-23-day-old mice expressing the human SCN1A GEFS+ mutation R1648H to prolonged hyperthermia, and then examined seizure and behavioral phenotypes during adulthood. We found that early-life FSs resulted in lower latencies to induced seizures, increased severity of spontaneous seizures, hyperactivity, and impairments in social behavior and recognition memory during adulthood. Biophysical analysis of brain slice preparations revealed an increase in epileptiform activity in CA3 pyramidal neurons along with increased action potential firing, providing a mechanistic basis for the observed worsening of adult phenotypes. These findings demonstrate the long-term negative impact of early-life FSs on disease outcomes. This has important implications for the clinical management of this patient population and highlights the need for therapeutic interventions that could ameliorate disease progression.
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Affiliation(s)
- Stacey B B Dutton
- Department of Human Genetics, Emory University, Atlanta, GA 30022, USA; Department of Biology, Agnes Scott College, Atlanta, GA 30030, USA
| | - Karoni Dutt
- Departments of Microbiology & Molecular Genetics and Anatomy & Neurobiology, University of California, Irvine, CA 92697, USA
| | - Ligia A Papale
- Department of Human Genetics, Emory University, Atlanta, GA 30022, USA
| | - Sandra Helmers
- Department of Neurology, Emory University, Atlanta, GA 30022, USA
| | - Alan L Goldin
- Departments of Microbiology & Molecular Genetics and Anatomy & Neurobiology, University of California, Irvine, CA 92697, USA
| | - Andrew Escayg
- Department of Human Genetics, Emory University, Atlanta, GA 30022, USA.
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10
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Hong Z, Tian Y, Qi M, Li Y, Du Y, Chen L, Liu W, Chen L. Transient Receptor Potential Vanilloid 4 Inhibits γ-Aminobutyric Acid-Activated Current in Hippocampal Pyramidal Neurons. Front Mol Neurosci 2016; 9:77. [PMID: 27616980 PMCID: PMC4999446 DOI: 10.3389/fnmol.2016.00077] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 08/10/2016] [Indexed: 12/26/2022] Open
Abstract
The balance between excitatory and inhibitory neurotransmitter systems is crucial for the modulation of neuronal excitability in the central nervous system (CNS). The activation of transient receptor potential vanilloid 4 (TRPV4) is reported to enhance the response of hippocampal glutamate receptors, but whether the inhibitory neurotransmitter system can be regulated by TRPV4 remains unknown. γ-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the CNS. Here, we show that application of transient receptor potential vanilloid 4 (TRPV4) synthetic (GSK1016790A or 4α-PDD) or endogenous agonist (5,6-EET) inhibited GABA-activated current (IGABA) in hippocampal CA1 pyramidal neurons, which was blocked by specific antagonists of TRPV4 and of GABAA receptors. GSK1016790A increased the phosphorylated AMP-activated protein kinase (p-AMPK) and decreased the phosphorylated protein kinase B (p-Akt) protein levels, which was attenuated by removing extracellular calcium or by a calcium/calmodulin-dependent protein kinase kinase-β antagonist. GSK1016790A-induced decrease of p-Akt protein level was sensitive to an AMPK antagonist. GSK1016790A-inhibited IGABA was blocked by an AMPK antagonist or a phosphatidyl inositol 3 kinase (PI3K) agonist. GSK1016790A-induced inhibition of IGABA was also significantly attenuated by a protein kinase C (PKC) antagonist but was unaffected by protein kinase A or calcium/calmodulin-dependent protein kinase II antagonist. We conclude that activation of TRPV4 inhibits GABAA receptor, which may be mediated by activation of AMPK and subsequent down-regulation of PI3K/Akt signaling and activation of PKC signaling. Inhibition of GABAA receptors may account for the neuronal hyperexcitability caused by TRPV4 activation.
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Affiliation(s)
- Zhiwen Hong
- Department of Physiology, Nanjing Medical University Nanjing, China
| | - Yujing Tian
- Department of Physiology, Nanjing Medical University Nanjing, China
| | - Mengwen Qi
- Department of Physiology, Nanjing Medical University Nanjing, China
| | - Yingchun Li
- Department of Physiology, Nanjing Medical University Nanjing, China
| | - Yimei Du
- Research Center of Ion Channelopathy, Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology Wuhan, China
| | - Lei Chen
- Department of Physiology, Nanjing Medical University Nanjing, China
| | - Wentao Liu
- Department of Pharmacology, Nanjing Medical University Nanjing, China
| | - Ling Chen
- Department of Physiology, Nanjing Medical University Nanjing, China
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11
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Brisch R, Bielau H, Saniotis A, Wolf R, Bogerts B, Krell D, Steiner J, Braun K, Krzyżanowska M, Krzyżanowski M, Jankowski Z, Kaliszan M, Bernstein HG, Gos T. Calretinin and parvalbumin in schizophrenia and affective disorders: a mini-review, a perspective on the evolutionary role of calretinin in schizophrenia, and a preliminary post-mortem study of calretinin in the septal nuclei. Front Cell Neurosci 2015; 9:393. [PMID: 26578879 PMCID: PMC4624860 DOI: 10.3389/fncel.2015.00393] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 09/22/2015] [Indexed: 12/14/2022] Open
Abstract
OBJECTIVE The septal nuclei are important limbic regions that are involved in emotional behavior and connect to various brain regions such as the habenular complex. Both the septal nuclei and the habenular complex are involved in the pathology of schizophrenia and affective disorders. METHODS We characterized the number and density of calretinin-immunoreactive neurons in the lateral, medial, and dorsal subregions of the septal nuclei in three groups of subjects: healthy control subjects (N = 6), patients with schizophrenia (N = 10), and patients with affective disorders (N = 6). RESULTS Our mini-review of the combined role of calretinin and parvalbumin in schizophrenia and affective disorders summarizes 23 studies. We did not observe significant differences in the numbers of calretinin-immunoreactive neurons or neuronal densities in the lateral, medial, and dorsal septal nuclei of patients with schizophrenia or patients with affective disorders compared to healthy control subjects. CONCLUSIONS Most post-mortem investigations of patients with schizophrenia have indicated significant abnormalities of parvalbumin-immunoreactive neurons in various brain regions including the hippocampus, the anterior cingulate cortex, and the prefrontal cortex in schizophrenia. This study also provides an explanation from an evolutionary perspective for why calretinin is affected in schizophrenia.
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Affiliation(s)
- Ralf Brisch
- Department of Forensic Medicine, Medical University of Gdańsk Gdańsk, Poland
| | - Hendrik Bielau
- Department of Psychiatry and Psychotherapy, Otto-von-Guericke-University of Magdeburg Magdeburg, Germany
| | - Arthur Saniotis
- School of Medicine, The University of Adelaide Adelaide, SA, Australia ; Institute of Evolutionary Medicine, University of Zurich Zurich, Switzerland
| | - Rainer Wolf
- Department of Psychiatry and Psychotherapy, Ruhr University Bochum Bochum, Germany
| | - Bernhard Bogerts
- Department of Psychiatry and Psychotherapy, Otto-von-Guericke-University of Magdeburg Magdeburg, Germany ; Center for Behavioral Brain Sciences Magdeburg, Germany
| | - Dieter Krell
- Department of Psychiatry and Psychotherapy, Otto-von-Guericke-University of Magdeburg Magdeburg, Germany
| | - Johann Steiner
- Department of Psychiatry and Psychotherapy, Otto-von-Guericke-University of Magdeburg Magdeburg, Germany ; Center for Behavioral Brain Sciences Magdeburg, Germany
| | - Katharina Braun
- Center for Behavioral Brain Sciences Magdeburg, Germany ; Department of Zoology/Developmental Neurobiology, Institute of Biology, Otto-von-Guericke-University of Magdeburg Magdeburg, Germany
| | - Marta Krzyżanowska
- Department of Forensic Medicine, Medical University of Gdańsk Gdańsk, Poland
| | - Maciej Krzyżanowski
- Department of Forensic Medicine, Medical University of Gdańsk Gdańsk, Poland
| | - Zbigniew Jankowski
- Department of Forensic Medicine, Medical University of Gdańsk Gdańsk, Poland
| | - Michał Kaliszan
- Department of Forensic Medicine, Medical University of Gdańsk Gdańsk, Poland
| | - Hans-Gert Bernstein
- Department of Psychiatry and Psychotherapy, Otto-von-Guericke-University of Magdeburg Magdeburg, Germany
| | - Tomasz Gos
- Department of Forensic Medicine, Medical University of Gdańsk Gdańsk, Poland
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Deng R, Koenig MA, Young LM, Jia X. Early Quantitative Gamma-Band EEG Marker is Associated with Outcomes After Cardiac Arrest and Targeted Temperature Management. Neurocrit Care 2015; 23:262-73. [PMID: 26130405 PMCID: PMC4560606 DOI: 10.1007/s12028-015-0157-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
BACKGROUND Brain recovery after cardiac arrest (CA) is sensitive to temperature. Yet the effect of temperature management on different EEG frequency bands has not been elucidated. A novel quantitative EEG algorithm, sub-band information quantity (SIQ), was applied to evaluate EEG recovery and outcomes after CA. METHODS Twenty-four Wistar rats undergoing 7-min CA were randomly assigned to immediate hypothermia (32-34 °C), normothermia (36.5-37.5 °C), or hyperthermia (38.5-39.5 °C) (n = 8). EEG was recorded continuously for the first 8 h and then for serial 30-min epochs daily. The neurologic deficit score (NDS) at 72-h was the primary functional outcome. Another four rats without brain injury were added as a control. RESULTS Better recovery of gamma-band SIQ was found in the hypothermia group (0.60 ± 0.03) compared with the normothermia group (0.40 ± 0.03) (p < 0.01) and in the normothermia group compared with the hyperthermia group (0.34 ± 0.03) (p < 0.05). The NDS was also improved in the lower temperature groups: hypothermia [median (25th, 75th), 74 (61, 74)] versus normothermia [49 (47, 61)] versus hyperthermia [43 (0, 50)] (p < 0.01). Throughout the 72-h experiment, the gamma-band SIQ showed the strongest correlation at every time point (ranging 0.520-0.788 from 30-min to 72-h post-resuscitation, all p < 0.05) whereas the delta-band SIQ had poor correlation with the 72-h NDS. No significant difference of sub-band EEG was found with temperature manipulation alone. CONCLUSIONS Recovery of gamma-band SIQ-qEEG was strongly associated with functional outcomes after CA. Induced hypothermia was associated with faster recovery of gamma-band SIQ and improved functional outcomes. Targeted temperature management primarily affected gamma frequency oscillations but not delta rhythm.
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Affiliation(s)
- Ruoxian Deng
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Matthew A. Koenig
- Department of Medicine, The University of Hawaii John A. Burns School of Medicine, Honolulu, HI 96813
- Neuroscience Institute, The Queen’s Medical Center, Honolulu, HI 96813
| | - Leanne Moon Young
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Xiaofeng Jia
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, MD 21201
- Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201
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Functional and structural deficits of the dentate gyrus network coincide with emerging spontaneous seizures in an Scn1a mutant Dravet Syndrome model during development. Neurobiol Dis 2015; 77:35-48. [PMID: 25725421 DOI: 10.1016/j.nbd.2015.02.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 01/03/2015] [Accepted: 02/16/2015] [Indexed: 12/27/2022] Open
Abstract
Dravet syndrome (DS) is characterized by severe infant-onset myoclonic epilepsy along with delayed psychomotor development and heightened premature mortality. A primary monogenic cause is mutation of the SCN1A gene, which encodes the voltage-gated sodium channel subunit Nav1.1. The nature and timing of changes caused by SCN1A mutation in the hippocampal dentate gyrus (DG) network, a core area for gating major excitatory input to hippocampus and a classic epileptogenic zone, are not well known. In particularly, it is still not clear whether the developmental deficit of this epileptogenic neural network temporally matches with the progress of seizure development. Here, we investigated the emerging functional and structural deficits of the DG network in a novel mouse model (Scn1a(E1099X/+)) that mimics the genetic deficit of human DS. Scn1a(E1099X/+) (Het) mice, similarly to human DS patients, exhibited early spontaneous seizures and were more susceptible to hyperthermia-induced seizures starting at postnatal week (PW) 3, with seizures peaking at PW4. During the same period, the Het DG exhibited a greater reduction of Nav1.1-expressing GABAergic neurons compared to other hippocampal areas. Het DG GABAergic neurons showed altered action potential kinetics, reduced excitability, and generated fewer spontaneous inhibitory inputs into DG granule cells. The effect of reduced inhibitory input to DG granule cells was exacerbated by heightened spontaneous excitatory transmission and elevated excitatory release probability in these cells. In addition to electrophysiological deficit, we observed emerging morphological abnormalities of DG granule cells. Het granule cells exhibited progressively reduced dendritic arborization and excessive spines, which coincided with imbalanced network activity and the developmental onset of spontaneous seizures. Taken together, our results establish the existence of significant structural and functional developmental deficits of the DG network and the temporal correlation between emergence of these deficits and the onset of seizures in Het animals. Most importantly, our results uncover the developmental deficits of neural connectivity in Het mice. Such structural abnormalities likely further exacerbate network instability and compromise higher-order cognitive processing later in development, and thus highlight the multifaceted impacts of Scn1a deficiency on neural development.
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Gu F, Hazra A, Aulakh A, Žiburkus J. Purinergic control of hippocampal circuit hyperexcitability in Dravet syndrome. Epilepsia 2014; 55:245-55. [PMID: 24417577 DOI: 10.1111/epi.12487] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2013] [Indexed: 02/06/2023]
Abstract
OBJECTIVE Severe myoclonic epilepsy in infancy (SMEI) or Dravet syndrome is one of the most devastating childhood epilepsies. Children with SMEI have febrile and afebrile seizures (FS and aFS), ataxia, and social and cognitive dysfunctions. SMEI is pharmacologically intractable and can be fatal in 10-20% of patients. It remains to be elucidated how channelopathies that cause SMEI impact synaptic activities in key neural circuits, and there is an ongoing critical need for alternative methods of controlling seizures in SMEI. Using the SCN1A gene knock-in mouse model of SMEI (mSMEI), we studied hippocampal cell and circuit excitability, particularly during hyperthermia, and tested whether an adenosine A1 receptor (A1R) agonist can reliably control hippocampal circuit hyperexcitability. METHODS Using a combination of electrophysiology (extracellular and whole-cell voltage clamp) and fast voltage-sensitive dye imaging (VSDI), we quantified synaptic excitation and inhibition, spatiotemporal characteristics of neural circuit activity, and hyperthermia-induced febrile seizure-like events (FSLEs) in juvenile mouse hippocampal slices. We used hyperthermia to elicit FSLEs in hippocampal slices, while making use of adenosine A1R agonist N6-cyclopentyladenosine (CPA) to control abnormally widespread neural activity and FSLEs. RESULTS We discovered a significant excitation/inhibition (E/I) imbalance in mSMEI hippocampi, in which inhibition was decreased and excitation increased. This imbalance was associated with an increased spatial extent of evoked neural circuit activation and a lowered FSLE threshold. We found that a low concentration (50 nm) of CPA blocked FSLEs and reduced the spatial extent of abnormal neural activity spread while preserving basal levels of excitatory synaptic transmission. SIGNIFICANCE Our study reveals significant hippocampal synapse and circuit dysfunctions in mSMEI and demonstrates that the A1R agonist CPA can reliably control hippocampal hyperexcitability and FSLEs in vitro. These findings may warrant further investigations of purinergic agonists as part of the development of new therapeutic approaches for Dravet syndrome.
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Affiliation(s)
- Feng Gu
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, U.S.A
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15
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Nakamura Y, Shi X, Numata T, Mori Y, Inoue R, Lossin C, Baram TZ, Hirose S. Novel HCN2 mutation contributes to febrile seizures by shifting the channel's kinetics in a temperature-dependent manner. PLoS One 2013; 8:e80376. [PMID: 24324597 PMCID: PMC3851455 DOI: 10.1371/journal.pone.0080376] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 10/02/2013] [Indexed: 12/27/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channel-mediated currents, known as I h, are involved in the control of rhythmic activity in neuronal circuits and in determining neuronal properties including the resting membrane potential. Recent studies have shown that HCN channels play a role in seizure susceptibility and in absence and limbic epilepsy including temporal lobe epilepsy following long febrile seizures (FS). This study focused on the potential contributions of abnormalities in the HCN2 isoform and their role in FS. A novel heterozygous missense mutation in HCN2 exon 1 leading to p.S126L was identified in two unrelated patients with FS. The mutation was inherited from the mother who had suffered from FS in a pedigree. To determine the effect of this substitution we conducted whole-cell patch clamp electrophysiology. We found that mutant channels had elevated sensitivity to temperature. More specifically, they displayed faster kinetics at higher temperature. Kinetic shift by change of temperature sensitivity rather than the shift of voltage dependence led to increased availability of I h in conditions promoting FS. Responses to cyclic AMP did not differ between wildtype and mutant channels. Thus, mutant HCN2 channels cause significant cAMP-independent enhanced availability of I h during high temperatures, which may contribute to hyperthermia-induced neuronal hyperexcitability in some individuals with FS.
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Affiliation(s)
- Yuki Nakamura
- Department of Pediatrics, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
- The Research Institute for the Molecular Pathomechanisms of Epilepsy, Fukuoka University, Fukuoka, Japan
| | - Xiuyu Shi
- The Research Institute for the Molecular Pathomechanisms of Epilepsy, Fukuoka University, Fukuoka, Japan
- Department of Pediatrics, Chinese PLA General Hospital, Beijing, China
| | - Tomohiro Numata
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Yasuo Mori
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Ryuji Inoue
- Department of Physiology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - Christoph Lossin
- Department of Neurology, School of Medicine University of California Davis, Sacramento, California, United States of America
| | - Tallie Z. Baram
- Departments of Anatomy & Neurobiology, Pediatrics, and Neurology, University of California Irvine, Irvine, California, United States of America
| | - Shinichi Hirose
- Department of Pediatrics, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
- The Research Institute for the Molecular Pathomechanisms of Epilepsy, Fukuoka University, Fukuoka, Japan
- * E-mail:
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16
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Kim JA, Connors BW. High temperatures alter physiological properties of pyramidal cells and inhibitory interneurons in hippocampus. Front Cell Neurosci 2012; 6:27. [PMID: 22783167 PMCID: PMC3390787 DOI: 10.3389/fncel.2012.00027] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 06/13/2012] [Indexed: 01/14/2023] Open
Abstract
Temperature has multiple effects on neurons, yet little is known about the effects of high temperature on the physiology of mammalian central neurons. Hyperthermia can influence behavior and cause febrile seizures. We studied the effects of acute hyperthermia on the immature hippocampus in vitro by recording from pyramidal neurons and inhibitory oriens-lacunosum moleculare (O-LM) interneurons (identified by green fluorescent protein (GFP) expression in the GIN mouse line). Warming to 41°C caused depolarization, spontaneous action potentials, reduced input resistance and membrane time constant, and increased spontaneous synaptic activity of most pyramidal cells and O-LM interneurons. Pyramidal neurons of area CA3 were more strongly excited by hyperthermia than those of area CA1. About 90% of O-LM interneurons in both CA1 and CA3 increased their firing rates at hyperthermic temperatures; interneurons in CA3 fired faster than those in CA1 on average. Blockade of fast synaptic transmission did not abolish the effect of hyperthermia on neuronal excitability. Our results suggest that hyperthermia increases hippocampal excitability, particularly in seizure-prone area CA3, by altering the intrinsic membrane properties of pyramidal cells and interneurons.
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Affiliation(s)
- Jennifer A Kim
- Department of Neuroscience, Brown University, Providence RI, USA
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17
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Hyperthermia induces epileptiform discharges in cultured rat cortical neurons. Brain Res 2011; 1417:87-102. [DOI: 10.1016/j.brainres.2011.08.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2011] [Revised: 08/08/2011] [Accepted: 08/11/2011] [Indexed: 01/28/2023]
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Abstract
This review focuses upon the past 8 years of research on hyperthermic effects on behavior. Heat stress and heat stoke become severe conditions when body temperatures exceed 40°C as this can lead to delirium, convulsions, coma, and death. The animal literature indicates that hyperthermia can increase glutamatergic and decrease GABAergic neurotransmission. Interestingly, µ-opiate receptor antagonists can attenuate the morphological and biochemical changes in brain, as well as, ameliorate some behavioral deficits induced by heart stress. In humans, heat stress can produce detrimental effects on motor and cognitive performance. Since most cognitive tasks require a motor response, some cognitive deficiencies may be attributed to decreased motor performance. Although hyperthermia may exert more deleterious effects on complex than simple cognitive tasks, systematic studies are needed to examine the effects of different levels and durations of hyperthermia (irrespective of dehydration) on cognition. Additionally, body temperatures should be carefully monitored where controls are run for baseline or brief exposures to a hyperthermic environment. Acute radiofrequency exposure can disrupt behavior when body temperatures increase >1°C with whole body SAR between 3.2-8.4 W/kg and time-averaged power densities at 8-140 mW/cm(2). Effects of lower levels of radiation are conflicting and some experiments fail to replicate even with the original investigators. This suggests either that brief exposure to the radiation is at a threshold where some individuals are affected while others are not, or that these levels are innocuous. Nevertheless, thermal changes appear to account for almost all of the behavioral effects reported.
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Affiliation(s)
- William C Wetsel
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC 27710, USA.
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19
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Förstera B, Belaidi AA, Jüttner R, Bernert C, Tsokos M, Lehmann TN, Horn P, Dehnicke C, Schwarz G, Meier JC. Irregular RNA splicing curtails postsynaptic gephyrin in the cornu ammonis of patients with epilepsy. Brain 2010; 133:3778-94. [DOI: 10.1093/brain/awq298] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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20
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Ohno Y, Sofue N, Ishihara S, Mashimo T, Sasa M, Serikawa T. Scn1a missense mutation impairs GABAA receptor-mediated synaptic transmission in the rat hippocampus. Biochem Biophys Res Commun 2010; 400:117-22. [PMID: 20707984 DOI: 10.1016/j.bbrc.2010.08.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Accepted: 08/06/2010] [Indexed: 02/07/2023]
Abstract
Mutations of the Na(v)1.1 channel subunit SCN1A have been implicated in the pathogenesis of human febrile seizures (FS). We have recently developed hyperthermia-induced seizure-susceptible (Hiss) rat, a novel rat model of FS, which carries a missense mutation (N1417H) in Scn1a[1]. Here, we conducted electrophysiological studies to clarify the influences of the Scn1a mutation on the hippocampal synaptic transmission, specifically focusing on the GABAergic system. Hippocampal slices were prepared from Hiss or F344 (control) rats and maintained in artificial cerebrospinal fluid saturated with 95% O(2) and 5% CO(2)in vitro. Single neuron activity was recorded from CA1 pyramidal neurons and their responses to the test (unconditioned) or paired pulse (PP) stimulation of the Schaffer collateral/commissural fibers were evaluated. Hiss rats were first tested for pentylenetetrazole-induced seizures and confirmed to show high seizure susceptibility to the blockade of GAGA(A) receptors. The Scn1a mutation in Hiss rats did not directly affect spike generation (i.e., number of evoked spikes and firing threshold) of the CA1 pyramidal neurons elicited by the Schaffer collateral/commissural stimulation. However, GABA(A) receptor-mediated inhibition of pyramidal neurons by the PP stimulation was significantly disrupted in Hiss rats, yielding a significant increase in the number of PP-induced firings at PP intervals of 32-256ms. The present study shows that the Scn1a missense mutation preferentially impairs GABA(A) receptor-mediated synaptic transmission without directly altering the excitability of the pyramidal neurons in the hippocampus, which may be linked to the pathogenesis of FS.
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Affiliation(s)
- Yukihiro Ohno
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka 569-1094, Japan.
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Koyama R, Matsuki N. Novel etiological and therapeutic strategies for neurodiseases: mechanisms and consequences of febrile seizures: lessons from animal models. J Pharmacol Sci 2010; 113:14-22. [PMID: 20424387 DOI: 10.1254/jphs.09r19fm] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Febrile seizures (FS) are the most common type of convulsive events in infancy and childhood. Genetic and environmental elements have been suggested to contribute to FS. FS can be divided into simple and complex types, the former being benign, whereas it is controversial whether complex FS have an association with the development of temporal lobe epilepsy (TLE) in later life. In the hippocampus of TLE patients, several structural and functional alterations take place that render the region an epileptic foci. Thus, it is important to clarify the cellular and molecular changes in the hippocampus after FS and to determine whether they are epileptogenic. To achieve this goal, human studies are too limited because the sample tissues are only available from adult patients in the advanced and drug-resistant stages of the disease, masking the underlying etiology. These facts have inspired researchers to take advantage of well-established animal models of FS to answer the following questions: 1) How does hyperthermia induce FS? 2) Do FS induce neuroanatomical changes? 3) Do FS induce neurophysiological changes? 4) Do FS affect the behavior in later life? Here we introduce and discuss accumulating reports to answer these questions.
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Affiliation(s)
- Ryuta Koyama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Japan.
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Qu L, Boyce R, Leung LS. Seizures in the developing brain result in a long-lasting decrease in GABAB inhibitory postsynaptic currents in the rat hippocampus. Neurobiol Dis 2010; 37:704-10. [DOI: 10.1016/j.nbd.2009.12.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2009] [Revised: 11/27/2009] [Accepted: 12/09/2009] [Indexed: 11/16/2022] Open
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Qu L, Leung LS. Effects of temperature elevation on neuronal inhibition in hippocampal neurons of immature and mature rats. J Neurosci Res 2010; 87:2773-85. [PMID: 19396879 DOI: 10.1002/jnr.22105] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Febrile seizures are the most common seizure type in children, and hyperthermia may contribute to seizure generation during fever. We have previously demonstrated that hyperthermia suppressed gamma-aminobutyric acid (GABA)-ergic synaptic transmission in CA1 neurons of immature rats. However, whether this suppression is age-dependent is unknown. Moreover, it is unclear whether hyperthermia has differential effects on neuronal inhibition in CA1 pyramidal cells (PCs) and dentate gyrus granule cells (GCs). In this study, we investigated the effects of hyperthermia on GABA(A) and GABA(B) receptor-mediated inhibitory postsynaptic currents (IPSCs) in CA1 and DG neurons from immature (11-17 days old) and mature (6-8 weeks old) rats using whole-cell recordings in vitro. In immature rats, hyperthermia decreased the peak amplitude of GABA(A) receptor-mediated IPSCs (GABA(A) IPSCs) in PCs but not in GCs. However, hyperthermia decreased the decay time constant of GABA(A) IPSCs to a similar extent in both PCs and GCs. In mature rats, hyperthermia decreased the peak amplitude but not the decay time constant of GABA(A) IPSCs in both PCs and GCs. Hyperthermia decreased charge transfer (area) of the GABA(A) IPSC of PCs more in immature than in mature rats. In contrast, hyperthermia decreased the GABA(B) receptor-mediated IPSCs to the same degree in immature and mature rats, for either CA1 or DG neurons. Because the hippocampus has been found to be involved in hyperthermia-induced behavioral seizures in immature rats, we suggest that the higher sensitivity of CA1 inhibitory synaptic function to hyperthermia in immature compared with mature rats might partially explain the higher susceptibility for febrile seizures in immature animals.
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Affiliation(s)
- Lintao Qu
- Graduate Program in Neuroscience, University of Western Ontario, London, Ontario, Canada
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Abstract
Febrile seizures (FSs) are seizures that occur during fever, usually at the time of a cold or flu, and represent the most common cause of seizures in the pediatric population. Up to 5% of children between the ages of six months and five years-of-age will experience a FS. Clinically these seizures are categorized as benign events with little impact on the growth and development of the child. However, studies have linked the occurrence of FSs to an increased risk of developing adult epileptic disorders. There are many unanswered questions about FSs, such as the mechanism of their generation, the long-term effects of these seizures, and their role in epileptogenesis. Answers are beginning to emerge based on results from animal studies. This review summarizes the current literature on animal models of FSs, mechanisms underlying the seizures, and functional, structural, and molecular changes that may result from them.
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Scantlebury MH, Heida JG. Febrile seizures and temporal lobe epileptogenesis. Epilepsy Res 2009; 89:27-33. [PMID: 20005077 DOI: 10.1016/j.eplepsyres.2009.11.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2009] [Revised: 10/26/2009] [Accepted: 11/07/2009] [Indexed: 11/19/2022]
Abstract
Febrile seizures (FS) are a common neurological disorder that affects children. Simple FS are thought to be benign but experimental and clinical evidence support that the risk of developing epilepsy after FS increases if the FS are prolonged and the brain is abnormal. In addition, prolonged FS (PFS) have many deleterious long-term effects characterized mainly in the hippocampus but may involve the whole brain and that prompt abortive treatment of PFS may prevent some of the adverse effects. This review focuses on some of the key factors involved in the generation of FS, factors leading to PFS and potential mechanisms and functional correlates leading to temporal lobe epilepsy (TLE).
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Affiliation(s)
- Morris H Scantlebury
- Saul R. Korey Department of Neurology, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York, USA.
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Qu L, Leung LS. Mechanisms of hyperthermia-induced depression of GABAergic synaptic transmission in the immature rat hippocampus. J Neurochem 2008; 106:2158-69. [DOI: 10.1111/j.1471-4159.2008.05576.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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