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Dong P, Bakhurin K, Li Y, Mikati MA, Cui J, Grill WM, Yin HH, Yang H. Attenuating midline thalamus bursting to mitigate absence epilepsy. Proc Natl Acad Sci U S A 2024; 121:e2403763121. [PMID: 38968111 DOI: 10.1073/pnas.2403763121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 05/31/2024] [Indexed: 07/07/2024] Open
Abstract
Advancing the mechanistic understanding of absence epilepsy is crucial for developing new therapeutics, especially for patients unresponsive to current treatments. Utilizing a recently developed mouse model of absence epilepsy carrying the BK gain-of-function channelopathy D434G, here we report that attenuating the burst firing of midline thalamus (MLT) neurons effectively prevents absence seizures. We found that enhanced BK channel activity in the BK-D434G MLT neurons promotes synchronized bursting during the ictal phase of absence seizures. Modulating MLT neurons through pharmacological reagents, optogenetic stimulation, or deep brain stimulation effectively attenuates burst firing, leading to reduced absence seizure frequency and increased vigilance. Additionally, enhancing vigilance by amphetamine, a stimulant medication, or physical perturbation also effectively suppresses MLT bursting and prevents absence seizures. These findings suggest that the MLT is a promising target for clinical interventions. Our diverse approaches offer valuable insights for developing next generation therapeutics to treat absence epilepsy.
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Affiliation(s)
- Ping Dong
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710
| | - Konstantin Bakhurin
- Department of Psychology and Neuroscience, Duke University, Durham, NC 27708
| | - Yuhui Li
- Department of Biomedical Engineering, Duke University, Durham, NC 27708
| | - Mohamad A Mikati
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710
- Department of Pediatrics, Duke University Medical Center, Durham, NC 27710
| | - Jianmin Cui
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, NC 27708
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710
- Department of Neurosurgery, Duke University Medical Center, Durham, NC 27710
| | - Henry H Yin
- Department of Psychology and Neuroscience, Duke University, Durham, NC 27708
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710
| | - Huanghe Yang
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710
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2
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Colombo S, Reddy HP, Petri S, Williams DJ, Shalomov B, Dhindsa RS, Gelfman S, Krizay D, Bera AK, Yang M, Peng Y, Makinson CD, Boland MJ, Frankel WN, Goldstein DB, Dascal N. Epilepsy in a mouse model of GNB1 encephalopathy arises from altered potassium (GIRK) channel signaling and is alleviated by a GIRK inhibitor. Front Cell Neurosci 2023; 17:1175895. [PMID: 37275776 PMCID: PMC10232839 DOI: 10.3389/fncel.2023.1175895] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 04/12/2023] [Indexed: 06/07/2023] Open
Abstract
De novo mutations in GNB1, encoding the Gβ1 subunit of G proteins, cause a neurodevelopmental disorder with global developmental delay and epilepsy, GNB1 encephalopathy. Here, we show that mice carrying a pathogenic mutation, K78R, recapitulate aspects of the disorder, including developmental delay and generalized seizures. Cultured mutant cortical neurons also display aberrant bursting activity on multi-electrode arrays. Strikingly, the antiepileptic drug ethosuximide (ETX) restores normal neuronal network behavior in vitro and suppresses spike-and-wave discharges (SWD) in vivo. ETX is a known blocker of T-type voltage-gated Ca2+ channels and G protein-coupled potassium (GIRK) channels. Accordingly, we present evidence that K78R results in a gain-of-function (GoF) effect by increasing the activation of GIRK channels in cultured neurons and a heterologous model (Xenopus oocytes)-an effect we show can be potently inhibited by ETX. This work implicates a GoF mechanism for GIRK channels in epilepsy, identifies a new mechanism of action for ETX in preventing seizures, and establishes this mouse model as a pre-clinical tool for translational research with predicative value for GNB1 encephalopathy.
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Affiliation(s)
- Sophie Colombo
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
| | - Haritha P. Reddy
- Department of Physiology and Pharmacology, School of Medicine, Tel Aviv University, Tel Aviv, Israel
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, India
| | - Sabrina Petri
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
| | - Damian J. Williams
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
| | - Boris Shalomov
- Department of Physiology and Pharmacology, School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ryan S. Dhindsa
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
| | - Sahar Gelfman
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
| | - Daniel Krizay
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
| | - Amal K. Bera
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, India
| | - Mu Yang
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
- Mouse NeuroBehavior Core Facility, Columbia University Irving Medical Center, New York, NY, United States
| | - Yueqing Peng
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
| | - Christopher D. Makinson
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, United States
- Department of Neuroscience, Columbia University, New York, NY, United States
| | - Michael J. Boland
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, United States
| | - Wayne N. Frankel
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY, United States
| | - David B. Goldstein
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY, United States
| | - Nathan Dascal
- Department of Physiology and Pharmacology, School of Medicine, Tel Aviv University, Tel Aviv, Israel
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Papazoglou A, Arshaad MI, Henseler C, Daubner J, Broich K, Hescheler J, Ehninger D, Haenisch B, Weiergräber M. Ca v3 T-Type Voltage-Gated Ca 2+ Channels and the Amyloidogenic Environment: Pathophysiology and Implications on Pharmacotherapy and Pharmacovigilance. Int J Mol Sci 2022; 23:ijms23073457. [PMID: 35408817 PMCID: PMC8998330 DOI: 10.3390/ijms23073457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 03/17/2022] [Accepted: 03/18/2022] [Indexed: 12/07/2022] Open
Abstract
Voltage-gated Ca2+ channels (VGCCs) were reported to play a crucial role in neurotransmitter release, dendritic resonance phenomena and integration, and the regulation of gene expression. In the septohippocampal system, high- and low-voltage-activated (HVA, LVA) Ca2+ channels were shown to be involved in theta genesis, learning, and memory processes. In particular, HVA Cav2.3 R-type and LVA Cav3 T-type Ca2+ channels are expressed in the medial septum-diagonal band of Broca (MS-DBB), hippocampal interneurons, and pyramidal cells, and ablation of both channels was proven to severely modulate theta activity. Importantly, Cav3 Ca2+ channels contribute to rebound burst firing in septal interneurons. Consequently, functional impairment of T-type Ca2+ channels, e.g., in null mutant mouse models, caused tonic disinhibition of the septohippocampal pathway and subsequent enhancement of hippocampal theta activity. In addition, impairment of GABA A/B receptor transcription, trafficking, and membrane translocation was observed within the septohippocampal system. Given the recent findings that amyloid precursor protein (APP) forms complexes with GABA B receptors (GBRs), it is hypothesized that T-type Ca2+ current reduction, decrease in GABA receptors, and APP destabilization generate complex functional interdependence that can constitute a sophisticated proamyloidogenic environment, which could be of potential relevance in the etiopathogenesis of Alzheimer’s disease (AD). The age-related downregulation of T-type Ca2+ channels in humans goes together with increased Aβ levels that could further inhibit T-type channels and aggravate the proamyloidogenic environment. The mechanistic model presented here sheds new light on recent reports about the potential risks of T-type Ca2+ channel blockers (CCBs) in dementia, as observed upon antiepileptic drug application in the elderly.
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Affiliation(s)
- Anna Papazoglou
- Experimental Neuropsychopharmacology, Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Kurt-Georg-Kiesinger-Allee 3, 53175 Bonn, Germany; (A.P.); (M.I.A.); (C.H.); (J.D.)
| | - Muhammad Imran Arshaad
- Experimental Neuropsychopharmacology, Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Kurt-Georg-Kiesinger-Allee 3, 53175 Bonn, Germany; (A.P.); (M.I.A.); (C.H.); (J.D.)
| | - Christina Henseler
- Experimental Neuropsychopharmacology, Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Kurt-Georg-Kiesinger-Allee 3, 53175 Bonn, Germany; (A.P.); (M.I.A.); (C.H.); (J.D.)
| | - Johanna Daubner
- Experimental Neuropsychopharmacology, Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Kurt-Georg-Kiesinger-Allee 3, 53175 Bonn, Germany; (A.P.); (M.I.A.); (C.H.); (J.D.)
| | - Karl Broich
- Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Kurt-Georg-Kiesinger-Allee 3, 53175 Bonn, Germany; (K.B.); (B.H.)
| | - Jürgen Hescheler
- Faculty of Medicine, Institute of Neurophysiology, University of Cologne, Robert-Koch-Str. 39, 50931 Cologne, Germany;
- Center of Physiology and Pathophysiology, Faculty of Medicine, University of Cologne, Robert-Koch-Str. 39, 50931 Cologne, Germany
| | - Dan Ehninger
- Translational Biogerontology, German Center for Neurodegenerative Diseases (Deutsches Zentrum für Neurodegenerative Erkrankungen, DZNE), Venusberg-Campus 1/99, 53127 Bonn, Germany;
- German Center for Neurodegenerative Diseases (Deutsches Zentrum für Neurodegenerative Erkrankungen, DZNE), Venusberg-Campus 1/99, 53127 Bonn, Germany
| | - Britta Haenisch
- Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Kurt-Georg-Kiesinger-Allee 3, 53175 Bonn, Germany; (K.B.); (B.H.)
- German Center for Neurodegenerative Diseases (Deutsches Zentrum für Neurodegenerative Erkrankungen, DZNE), Venusberg-Campus 1/99, 53127 Bonn, Germany
- Center for Translational Medicine, Medical Faculty, University of Bonn, 53113 Bonn, Germany
| | - Marco Weiergräber
- Experimental Neuropsychopharmacology, Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Kurt-Georg-Kiesinger-Allee 3, 53175 Bonn, Germany; (A.P.); (M.I.A.); (C.H.); (J.D.)
- Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Kurt-Georg-Kiesinger-Allee 3, 53175 Bonn, Germany; (K.B.); (B.H.)
- Faculty of Medicine, Institute of Neurophysiology, University of Cologne, Robert-Koch-Str. 39, 50931 Cologne, Germany;
- Center of Physiology and Pathophysiology, Faculty of Medicine, University of Cologne, Robert-Koch-Str. 39, 50931 Cologne, Germany
- Correspondence: ; Tel.: +49-228-99307-4358
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Jha M, Alam O, Naim MJ, Sharma V, Bhatia P, Sheikh AA, Nawaz F, Alam P, Manaithiya A, Kumar V, Nazar S, Siddiqui N. Recent advancement in the discovery and development of anti-epileptic biomolecules: An insight into structure activity relationship and Docking. Eur J Pharm Sci 2020; 153:105494. [PMID: 32730845 DOI: 10.1016/j.ejps.2020.105494] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/20/2020] [Accepted: 07/27/2020] [Indexed: 12/22/2022]
Abstract
Although there have been many advancements in scientific research and development, the cause of epilepsy still remains an open challenge. In spite of high throughput research in the field of anti-epileptic drugs, efficacy void is still prevalent before the researchers. Researchers have persistently been exploring all the possibilities to curb undesirable side effects of the anti-epileptic drugs or looking for a more substantial approach to diminish or cure epilepsy. The drug development has shown a hope to medicinal chemists and researchers to carry further research by going through a substantial literature survey. This review article attempts to describe the recent developments in the anti-epileptic agents, pertaining to different molecular scaffolds considering their structure-activity relationship, docking studies and their mechanism of actions.
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Affiliation(s)
- Mukund Jha
- Medicinal Chemistry and Molecular Modelling Lab, Department of Pharmaceutical Chemistry, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi, 110062, India
| | - Ozair Alam
- Medicinal Chemistry and Molecular Modelling Lab, Department of Pharmaceutical Chemistry, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi, 110062, India.
| | - Mohd Javed Naim
- Medicinal Chemistry and Molecular Modelling Lab, Department of Pharmaceutical Chemistry, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi, 110062, India
| | - Vrinda Sharma
- Medicinal Chemistry and Molecular Modelling Lab, Department of Pharmaceutical Chemistry, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi, 110062, India
| | - Parth Bhatia
- Medicinal Chemistry and Molecular Modelling Lab, Department of Pharmaceutical Chemistry, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi, 110062, India
| | - Aadil Ahmad Sheikh
- Medicinal Chemistry and Molecular Modelling Lab, Department of Pharmaceutical Chemistry, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi, 110062, India
| | - Farah Nawaz
- Medicinal Chemistry and Molecular Modelling Lab, Department of Pharmaceutical Chemistry, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi, 110062, India
| | - Perwaiz Alam
- Medicinal Chemistry and Molecular Modelling Lab, Department of Pharmaceutical Chemistry, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi, 110062, India
| | - Ajay Manaithiya
- Medicinal Chemistry and Molecular Modelling Lab, Department of Pharmaceutical Chemistry, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi, 110062, India
| | - Vivek Kumar
- Department of Cardiology, Fortis Heart Institute, New Delhi, 110025, India
| | - Shagufi Nazar
- Medicinal Chemistry and Molecular Modelling Lab, Department of Pharmaceutical Chemistry, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi, 110062, India
| | - Nadeem Siddiqui
- Medicinal Chemistry and Molecular Modelling Lab, Department of Pharmaceutical Chemistry, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi, 110062, India
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DEMİRTAŞ ŞAHİN T, UTKAN T, KARSON A, YAZIR Y, KARAOZ E. Genetik absans epilepsili WAG/Rij sıçanlarda kardiyovasküler değişiklikler: Kronik etosüksimid tedavisinin etkileri. CUKUROVA MEDICAL JOURNAL 2020. [DOI: 10.17826/cumj.724491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Sekar S, Marks WN, Gopalakrishnan V, Greba Q, Snutch TP, Howland JG, Taghibiglou C. Evidence for altered insulin signalling in the brains of genetic absence epilepsy rats from Strasbourg. Clin Exp Pharmacol Physiol 2020; 47:1530-1536. [PMID: 32304254 DOI: 10.1111/1440-1681.13326] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 04/12/2020] [Accepted: 04/13/2020] [Indexed: 01/15/2023]
Abstract
Insulin-mediated signalling in the brain is critical for neuronal functioning. Insulin resistance is implicated in the development of some neurological diseases, although changes associated with absence epilepsy have not been established yet. Therefore, we examined the major components of PI3K/Akt-mediated insulin signalling in cortical, thalamic, and hippocampal tissues collected from Genetic Absence Epilepsy Rats from Strasbourg (GAERS) and Non-Epileptic Control (NEC) rats. Insulin levels were also measured in plasma and cerebrospinal fluid (CSF). For the brain samples, the nuclear fraction (NF) and total homogenate (TH) were isolated and investigated for insulin signalling markers including insulin receptor beta (IRβ), IR substrate-1 and 2 (IRS1 & 2), phosphatase and tensin homologue (PTEN), phosphoinositide 3-kinase phospho-85 alpha (PI3K p85α), phosphatidylinositol 4,5-bisphosphate, phosphatidylinositol (3,4,5)-trisphosphate, protein kinase B (PKB/Akt1/2/3), glucose transporter-1 and 4 (GLUT1 & 4) and glycogen synthase kinase-3β (GSK3β) using western blotting. A significant increase in PTEN and GSK3β levels and decreased PI3K p85α and pAkt1/2/3 levels were observed in NF of GAERS cortical and hippocampal tissues. IRβ, IRS1, GLUT1, and GLUT4 levels were significantly decreased in hippocampal TH of GAERS compared to NEC. A non-significant increase in insulin levels was observed in plasma and CSF of GAERS rats. An insulin sensitivity assay showed decreased p-Akt level in cortical and hippocampal tissues. Together, altered hippocampal insulin signalling was more prominent in NF and TH compared to cortical and thalamic regions in GAERS. Restoring insulin signalling may improve the pathophysiology displayed by GAERS, including the spike-and-wave discharges that relate to absence seizures in patients.
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Affiliation(s)
- Sathiya Sekar
- Department of Anatomy, Physiology, Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Wendie N Marks
- Department of Anatomy, Physiology, Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Venkat Gopalakrishnan
- Department of Anatomy, Physiology, Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Quentin Greba
- Department of Anatomy, Physiology, Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Terrance P Snutch
- Michael Smith Laboratories and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
| | - John G Howland
- Department of Anatomy, Physiology, Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Changiz Taghibiglou
- Department of Anatomy, Physiology, Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
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Regulation and control roles of the basal ganglia in the development of absence epileptiform activities. Cogn Neurodyn 2019; 14:137-154. [PMID: 32015772 DOI: 10.1007/s11571-019-09559-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 09/02/2019] [Accepted: 09/30/2019] [Indexed: 10/25/2022] Open
Abstract
Absence epileptiform activities are traditionally considered to be primarily induced by abnormal interactions between the cortical and thalamic neurons, which form the thalamocortical circuit in the brain. The basal ganglia, as an organizational unit in the brain, has close input and output relationships with the thalamocortical circuit. Although several studies report that the basal ganglia may participate in controlling and regulating absence epileptiform activities, to date, there have been no studies regarding whether the basal ganglia directly cause absence epileptiform activities. In this paper, we built a basal ganglia-corticothalamic network model to determine the role of basal ganglia in this disease. We determined that absence epileptiform activities might be directly induced by abnormal coupling strengths on certain pivotal pathways in the basal ganglia. These epileptiform activities can be well controlled by the coupling strengths of three major pathways that project from the thalamocortical network to the basal ganglia. The results implied that the substantia nigra pars compacta (SNc) can be considered to be the effective treatment target area for inhibiting epileptiform activities, which supports the observations of previous studies. Particularly, as a major contribution of this paper, we determined that the final presentation position of the epileptic slow spike waves is not limited to the cerebral cortex; these waves may additionally appear in the thalamus, striatal medium spiny neurons, striatal fast spiking interneuron, the SNc, subthalamic nucleus, substantia nigra pars reticulata and globus pallidus pars externa. In addition, consistent with several previous studies, the delay in the network was observed to be a critical factor for inducing transitions between different types of absence epileptiform activities. Our new model not only explains the onset and control mechanism but also provides a unified framework to study similar problems in neuron systems.
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Celli R, Santolini I, Guiducci M, van Luijtelaar G, Parisi P, Striano P, Gradini R, Battaglia G, Ngomba RT, Nicoletti F. The α2δ Subunit and Absence Epilepsy: Beyond Calcium Channels? Curr Neuropharmacol 2018; 15:918-925. [PMID: 28290248 PMCID: PMC5652034 DOI: 10.2174/1570159x15666170309105451] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 01/16/2017] [Accepted: 03/06/2017] [Indexed: 02/08/2023] Open
Abstract
Background: Spike-wave discharges, underlying absence seizures, are generated within a cortico-thalamo-cortical network that involves the somatosensory cortex, the reticular thalamic nucleus, and the ventrobasal thalamic nuclei. Activation of T-type voltage-sensitive calcium channels (VSCCs) contributes to the pathological oscillatory activity of this network, and some of the first-line drugs used in the treatment of absence epilepsy inhibit T-type calcium channels. The α2δ subunit is a component of high voltage-activated VSCCs (i.e., L-, N-, P/Q-, and R channels) and studies carried out in heterologous expression systems suggest that it may also associate with T channels. The α2δ subunit is also targeted by thrombospondins, which regulate synaptogenesis in the central nervous system. Objective: To discuss the potential role for the thrombospondin/α2δ axis in the pathophysiology of absence epilepsy. Methods: We searched PubMed articles for the terms “absence epilepsy”, “T-type voltage-sensitive calcium channels”, “α2δ subunit”, “ducky mice”, “pregabalin”, “gabapentin”, “thrombospondins”, and included papers focusing this Review's scope. Results: We moved from the evidence that mice lacking the α2δ-2 subunit show absence seizures and α2δ ligands (gabapentin and pregabalin) are detrimental in the treatment of absence epilepsy. This suggests that α2δ may be protective against absence epilepsy via a mechanism that does not involve T channels. We discuss the interaction between thrombospondins and α2δ and its potential relevance in the regulation of excitatory synaptic formation in the cortico-thalamo-cortical network. Conclusion: We speculate on the possibility that the thrombospondin/α2δ axis is critical for the correct functioning of the cortico-thalamo-cortical network, and that abnormalities in this axis may play a role in the pathophysiology of absence epilepsy.
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Affiliation(s)
- Roberta Celli
- I.R.C.C.S. Neuromed, Neuropharmacology Unit, Pozzilli, (IS), Italy
| | - Ines Santolini
- I.R.C.C.S. Neuromed, Neuropharmacology Unit, Pozzilli, (IS), Italy
| | - Michela Guiducci
- Departments of Neurosciences, Mental Health and Sensory Organs, Experimental Medicine, and Physiology and Pharmacology, University Sapienza, Rome, Italy
| | - Gilles van Luijtelaar
- Donders Centre for Cognition, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen. Netherlands
| | - Pasquale Parisi
- Departments of Neurosciences, Mental Health and Sensory Organs, Experimental Medicine, and Physiology and Pharmacology, University Sapienza, Rome, Italy
| | - Pasquale Striano
- Pediatric Neurology and Muscular Diseases Unit, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, "G. Gaslini" Institute, Genova, Italy
| | - Roberto Gradini
- I.R.C.C.S. Neuromed, Neuropharmacology Unit, Pozzilli, (IS), Italy
| | | | - Richard T Ngomba
- University of Lincoln, School of Pharmacy, Lincoln, United Kingdom
| | - Ferdinando Nicoletti
- Department of Physiology and Pharmacology, University Sapienza, Piazzale Aldo Moro, 5, 00185 Rome, Italy
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Hu B, Guo Y, Shi F, Zou X, Dong J, Pan L, Yu M, Zhou C, Cheng Z, Tang W, Sun H, Chen L. The generation mechanism of spike-and-slow wave discharges appearing on thalamic relay nuclei. Sci Rep 2018; 8:4953. [PMID: 29563579 PMCID: PMC5862852 DOI: 10.1038/s41598-018-23280-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 03/08/2018] [Indexed: 12/19/2022] Open
Abstract
In this paper, we use a model modified from classic corticothalamic network(CT) to explore the mechanism of absence seizures appearing on specific relay nuclei (SRN) of the thalamus. It is found that typical seizure states appear on SRN through tuning several critical connection strengths in the model. In view of previous experimental and theoretical works which were mainly on epilepsy seizure phenomena appearing on excitatory pyramidal neurons (EPN) of the cortex, this is a novel model to consider the seizure observed on thalamus. In particular, the onset mechanism is different from previous theoretical studies. Inspired by some previous clinical and experimental studies, we employ the external stimuli voltage on EPN and SRN in the network, and observe that the seizure can be well inhibited by tuning the stimulus intensity appropriately. We further explore the effect of the signal transmission delays on seizures, and found that the polyspike phenomenon appears only when the delay is sufficiently large. The experimental data also confirmed our model. Since there is a complex network in the brain and all organizations are interacting closely with each other, the results obtained in this paper provide not only biological insights into the regulatory mechanisms but also a reference for the prevention and treatment of epilepsy in future.
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Affiliation(s)
- Bing Hu
- Institute of Applied Mathematics, Department of Mathematics and Statistics, College of Science, Huazhong Agricultural University, Wuhan, 430070, China.
- Key Laboratory of Systems Biology, CAS center for Excellence in Molecular Cell Science, Innovation Center for Cell Signaling Network, Institute of Biochemistry and Cell Biology, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China.
| | - Yu Guo
- Institute of Applied Mathematics, Department of Mathematics and Statistics, College of Science, Huazhong Agricultural University, Wuhan, 430070, China
| | - Feng Shi
- Institute of Applied Mathematics, Department of Mathematics and Statistics, College of Science, Huazhong Agricultural University, Wuhan, 430070, China
| | - Xiaoqiang Zou
- Institute of Applied Mathematics, Department of Mathematics and Statistics, College of Science, Huazhong Agricultural University, Wuhan, 430070, China
| | - Jing Dong
- Institute of Applied Mathematics, Department of Mathematics and Statistics, College of Science, Huazhong Agricultural University, Wuhan, 430070, China
| | - Long Pan
- Institute of Applied Mathematics, Department of Mathematics and Statistics, College of Science, Huazhong Agricultural University, Wuhan, 430070, China
| | - Min Yu
- Institute of Applied Mathematics, Department of Mathematics and Statistics, College of Science, Huazhong Agricultural University, Wuhan, 430070, China
| | - Chaowei Zhou
- Institute of Applied Mathematics, Department of Mathematics and Statistics, College of Science, Huazhong Agricultural University, Wuhan, 430070, China
| | - Zhang Cheng
- Institute of Applied Mathematics, Department of Mathematics and Statistics, College of Science, Huazhong Agricultural University, Wuhan, 430070, China
| | - Wanyue Tang
- Institute of Applied Mathematics, Department of Mathematics and Statistics, College of Science, Huazhong Agricultural University, Wuhan, 430070, China
| | - Haochen Sun
- Institute of Applied Mathematics, Department of Mathematics and Statistics, College of Science, Huazhong Agricultural University, Wuhan, 430070, China
| | - Luonan Chen
- Key Laboratory of Systems Biology, CAS center for Excellence in Molecular Cell Science, Innovation Center for Cell Signaling Network, Institute of Biochemistry and Cell Biology, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China.
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10
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Abstract
Epilepsy, characterized by spontaneous recurrent seizures (SRS), is a serious and common neurological disorder afflicting an estimated 1% of the population worldwide. Animal experiments, especially those utilizing small laboratory rodents, remain essential to understanding the fundamental mechanisms underlying epilepsy and to prevent, diagnose, and treat this disease. While much attention has been focused on epileptogenesis in animal models of epilepsy, there is little discussion on SRS, the hallmark of epilepsy. This is in part due to the technical difficulties of rigorous SRS detection. In this review, we comprehensively summarize both genetic and acquired models of SRS and discuss the methodology used to monitor and detect SRS in mice and rats.
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Affiliation(s)
- Bin Gu
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA.
| | - Katherine A Dalton
- Psychology & Neuroscience Program, University of North Carolina, Chapel Hill, NC 27599, USA
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11
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Control of absence epilepsy seizures in specific relay nuclei of thalamus. J Theor Biol 2017; 435:50-61. [PMID: 28918332 DOI: 10.1016/j.jtbi.2017.09.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 09/08/2017] [Accepted: 09/11/2017] [Indexed: 11/21/2022]
Abstract
In this paper, we used a classic basal ganglia-corticothalamic model(BGCT) to study the onset and control mechanism of absence epilepsy in specific relay nuclei (SRN) of thalamus. It was found that the seizure state may appear in SRN by turning the coupling strength -vsr and signal transmission delay τ on the route "Thalamic reticular nuclei (TRN) of thalamus ⟶ SRN". With increasing of -vsr, the seizure state appeared two times, and its onset mechanism has not been discussed in previous studies. The seizure activity can be well controlled by adjusting the activation level of the substantia nigra pars reticulata (SNr) in basal ganglia, which is a main output tissue to the corticothalamic system through two direct inhibitory pathways "SNr ⟶ SRN" and "SNr ⟶ TRN" in our model. We found that the interesting bidirectional regulation phenomenon appeared as considering the single pathway "SNr ⟶ SRN" and "SNr ⟶ TRN", or when they coexisted in one network, the mechanism of which is also different from some previous theoretical studies. At last, we pointed out that the mechanism obtained above can also explain the onset and control of the poly-spikes slow wave appeared in SRN by turning τ to large enough. Therefore, the results in the paper will further deepen our understanding of the generation and control mechanism of epilepsy disease.
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12
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Kim JB, Jung JM, Park MH, Lee EJ, Kwon DY. Negative myoclonus induced by gabapentin and pregabalin: A case series and systematic literature review. J Neurol Sci 2017; 382:36-39. [PMID: 29111014 DOI: 10.1016/j.jns.2017.09.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 09/11/2017] [Accepted: 09/14/2017] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Negative myoclonus is a jerky, brief, and sudden interruption of voluntary muscle contraction. Although gabapentin and pregabalin have been reported to induce positive myoclonus in some patients with impaired renal function, there are only a few studies describing pregabalin- or gabapentin-induced negative myoclonus. This study reviewed patients who had developed pregabalin- or gabapentin-induced negative myoclonus. METHODS We collected the patients with negative myoclonus who were referred to the department of neurology at a university-affiliated hospital and selected pregabalin- or gabapentin-induced negative myoclonus. Then reviewed the literature with respect to pregabalin- or gabapentin-induced negative myoclonus. RESULTS A total of 77 patients with negative myoclonus were reviewed. Among them, 21 neuropathic pain patients who were prescribed and developed negative myoclonus induced by pregabalin (9 cases) or gabapentin (12 cases). To prove causality of the drug, probable and certain level of category according to the WHO-UMC criteria were recruited. Of the 21 patients, 3 had impaired renal function, while 18 had normal renal function. Review of the literature identified 7 further cases (6 had normal renal function) with pregabalin- or gabapentin-induced negative myoclonus. CONCLUSION Pregabalin- and gabapentin-induced negative myoclonus can develop even in patients with normal renal function. Physicians should keep in mind the possibility of patients developing negative myoclonus under treatment of pregabalin or gabapentin even in short period of time and with low dosage, and in the normal range of renal function. Further prospective study investigating incidence and risk factors is warranted.
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Affiliation(s)
- Jung Bin Kim
- Department of Neurology, Korea University Anam Hospital, Korea University College of Medicine, Seoul, South Korea
| | - Jin-Man Jung
- Department of Neurology, Korea University Ansan Hospital, Korea University College of Medicine, Ansan, South Korea
| | - Moon-Ho Park
- Department of Neurology, Korea University Ansan Hospital, Korea University College of Medicine, Ansan, South Korea
| | - Eun Ju Lee
- Medical Library, Korea University, Seoul, South Korea
| | - Do-Young Kwon
- Department of Neurology, Korea University Ansan Hospital, Korea University College of Medicine, Ansan, South Korea.
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13
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Kim JH, Nam G. Synthesis and evaluation of 6-pyrazoylamido-3N-substituted azabicyclo[3,1,0]hexane derivatives as T-type calcium channel inhibitors for treatment of neuropathic pain. Bioorg Med Chem 2016; 24:5028-5035. [PMID: 27591007 DOI: 10.1016/j.bmc.2016.06.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 06/02/2016] [Accepted: 06/03/2016] [Indexed: 10/21/2022]
Abstract
A new series of aryls, including benzo[d]imidazole/isoxazole/pyrazole, conjugated to 3N-substituted-azabicyclo[3.1.0]hexane derivatives were designed and synthesized as inhibitors of T-type calcium channels. Among the synthesized compounds, 3N-R-substituted azabicyclo[3.1.0]hexane carboxamide derivatives containing 5-isobutyl-1-phenyl-pyrazole ring exhibited potent and selective T-channel inhibition and good metabolic stability without CYP450 inhibition. Compounds 10d and 10e contained hydrophobic substituents at the 3N-position and exhibited potent in vitro efficacy, as well as neuropathic pain alleviation in rats.
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Affiliation(s)
- Jung Hyun Kim
- Center for Neuro-Medicine, Brain Science Institute, Korea Institutes of Science and Technology (KIST), Seoul 136-791, Republic of Korea
| | - Ghilsoo Nam
- Center for Neuro-Medicine, Brain Science Institute, Korea Institutes of Science and Technology (KIST), Seoul 136-791, Republic of Korea; School of Science, University of Science and Technology, Daejeon 305-333, Republic of Korea.
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14
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Sharop BR, Boldyriev OI, Batiuk MY, Shtefan NL, Shuba YM. Compensatory reduction of Cav3.1 expression in thalamocortical neurons of juvenile rats of WAG/Rij model of absence epilepsy. Epilepsy Res 2015; 119:10-2. [PMID: 26656778 DOI: 10.1016/j.eplepsyres.2015.11.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Revised: 10/07/2015] [Accepted: 11/09/2015] [Indexed: 11/16/2022]
Abstract
Absence seizures are the non-convulsive form of generalized epilepsy critically dependent on T-type calcium channels (Cav3) in thalamic neurons. In humans, absences accompany only childhood or adolescent epileptic syndromes--though in its polygenic rat models WAG/Rij and GAERS the opposite developmental pattern is observed. Hereby we address this issue by transcriptional and functional study of thalamic Cav3 in juvenile (i.e., free of seizures) rats of the absence-prone WAG/Rij strain and their coevals of the maternal Wistar strain. First, we measured the low voltage-activated (LVA) Ca(2+) current in freshly isolated thalamocortical neurons from laterodorsal nucleus of thalamus. The difference between current densities in control (12.9 ± 1.8pA/pF) and absence epilepsy (7.9 ± 1.8pA/pF) groups reached ∼ 39%. Second, we assessed the contribution of different T-channel isoforms into the reduction of Cav3-mediated current in WAG/Rij juveniles by means of RT PCR. The expression of all three LVA calcium channels was revealed with the prevalence of G and I isoforms. The expression level of G isoform (Cav3.1) was 35% smaller in WAG/Rij strain if compared to the control animals while that of H and I isoforms (Cav3.2 and Cav3.3, respectively) remained stable. The weakened expression of Cav3.1 in juveniles of WAG/Rij rats could represent a compensatory mechanism determining the pattern of the age dependency in the disease manifestation by this model of absence epilepsy.
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Affiliation(s)
- Bizhan R Sharop
- Department of Nerve & Muscle Physiology, Bogomoletz Institute of Physiology, NASU, Bogomotetz Str., 4, Kiev, 01024, Ukraine; International Center of Molecular Physiology, NASU, Kyiv, Ukraine; State Key Laboratory of Molecular and Cellular Physiology, Kyiv, Ukraine.
| | - Oleksii I Boldyriev
- Department of Nerve & Muscle Physiology, Bogomoletz Institute of Physiology, NASU, Bogomotetz Str., 4, Kiev, 01024, Ukraine; International Center of Molecular Physiology, NASU, Kyiv, Ukraine; State Key Laboratory of Molecular and Cellular Physiology, Kyiv, Ukraine
| | - Mykhailo Y Batiuk
- International Center of Molecular Physiology, NASU, Kyiv, Ukraine; State Key Laboratory of Molecular and Cellular Physiology, Kyiv, Ukraine
| | - Nataliia L Shtefan
- Department of Nerve & Muscle Physiology, Bogomoletz Institute of Physiology, NASU, Bogomotetz Str., 4, Kiev, 01024, Ukraine
| | - Yaroslav M Shuba
- Department of Nerve & Muscle Physiology, Bogomoletz Institute of Physiology, NASU, Bogomotetz Str., 4, Kiev, 01024, Ukraine; International Center of Molecular Physiology, NASU, Kyiv, Ukraine; State Key Laboratory of Molecular and Cellular Physiology, Kyiv, Ukraine
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15
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Venzi M, Di Giovanni G, Crunelli V. A critical evaluation of the gamma-hydroxybutyrate (GHB) model of absence seizures. CNS Neurosci Ther 2015; 21:123-40. [PMID: 25403866 PMCID: PMC4335601 DOI: 10.1111/cns.12337] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 09/13/2014] [Accepted: 09/17/2014] [Indexed: 12/13/2022] Open
Abstract
Typical absence seizures (ASs) are nonconvulsive epileptic events which are commonly observed in pediatric and juvenile epilepsies and may be present in adults suffering from other idiopathic generalized epilepsies. Our understanding of the pathophysiological mechanisms of ASs has been greatly advanced by the availability of genetic and pharmacological models, in particular the γ-hydroxybutyrate (GHB) model which, in recent years, has been extensively used in studies in transgenic mice. GHB is an endogenous brain molecule that upon administration to various species, including humans, induces not only ASs but also a state of sedation/hypnosis. Analysis of the available data clearly indicates that only in the rat does there exist a set of GHB-elicited behavioral and EEG events that can be confidently classified as ASs. Other GHB activities, particularly in mice, appear to be mostly of a sedative/hypnotic nature: thus, their relevance to ASs requires further investigation. At the molecular level, GHB acts as a weak GABA-B agonist, while the existence of a GHB receptor remains elusive. The pre- and postsynaptic actions underlying GHB-elicited ASs have been thoroughly elucidated in thalamus, but little is known about the cellular/network effects of GHB in neocortex, the other brain region involved in the generation of ASs.
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Affiliation(s)
- Marcello Venzi
- Neuroscience DivisionSchool of BioscienceCardiff UniversityCardiffUK
| | - Giuseppe Di Giovanni
- Neuroscience DivisionSchool of BioscienceCardiff UniversityCardiffUK
- Department of Physiology and BiochemistryMalta UniversityMsida, Malta
| | - Vincenzo Crunelli
- Neuroscience DivisionSchool of BioscienceCardiff UniversityCardiffUK
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16
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Nieto-Rostro M, Sandhu G, Bauer CS, Jiruska P, Jefferys JGR, Dolphin AC. Altered expression of the voltage-gated calcium channel subunit α₂δ-1: a comparison between two experimental models of epilepsy and a sensory nerve ligation model of neuropathic pain. Neuroscience 2014; 283:124-37. [PMID: 24641886 PMCID: PMC4259901 DOI: 10.1016/j.neuroscience.2014.03.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 03/03/2014] [Accepted: 03/09/2014] [Indexed: 12/20/2022]
Abstract
The auxiliary α2δ-1 subunit of voltage-gated calcium channels is up-regulated in dorsal root ganglion neurons following peripheral somatosensory nerve damage, in several animal models of neuropathic pain. The α2δ-1 protein has a mainly presynaptic localization, where it is associated with the calcium channels involved in neurotransmitter release. Relevant to the present study, α2δ-1 has been shown to be the therapeutic target of the gabapentinoid drugs in their alleviation of neuropathic pain. These drugs are also used in the treatment of certain epilepsies. In this study we therefore examined whether the level or distribution of α2δ-1 was altered in the hippocampus following experimental induction of epileptic seizures in rats, using both the kainic acid model of human temporal lobe epilepsy, in which status epilepticus is induced, and the tetanus toxin model in which status epilepticus is not involved. The main finding of this study is that we did not identify somatic overexpression of α2δ-1 in hippocampal neurons in either of the epilepsy models, unlike the upregulation of α2δ-1 that occurs following peripheral nerve damage to both somatosensory and motor neurons. However, we did observe local reorganization of α2δ-1 immunostaining in the hippocampus only in the kainic acid model, where it was associated with areas of neuronal cell loss, as indicated by absence of NeuN immunostaining, dendritic loss, as identified by areas where microtubule-associated protein-2 immunostaining was missing, and reactive gliosis, determined by regions of strong OX42 staining.
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Affiliation(s)
- M Nieto-Rostro
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - G Sandhu
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - C S Bauer
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - P Jiruska
- Neuronal Networks Group, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham B15 2TT, UK
| | - J G R Jefferys
- Neuronal Networks Group, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham B15 2TT, UK
| | - A C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK.
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17
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Flow- and voltage-dependent blocking effect of ethosuximide on the inward rectifier K⁺ (Kir2.1) channel. Pflugers Arch 2014; 467:1733-46. [PMID: 25220134 DOI: 10.1007/s00424-014-1611-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 08/21/2014] [Accepted: 09/05/2014] [Indexed: 12/31/2022]
Abstract
Absence seizures are manifestations of abnormal thalamocortical oscillations characterized by spike-and-wave complexes in EEG. Ethosuximide (ETX) is one of the principal medications against absence seizures. We investigate the effect of ETX on the Kir2.1 channel, a prototypical inward rectifier K(+) channel possibly playing an important role in the setting of neuronal membrane potential. We demonstrate that the outward currents of Kir2.1 channels are significantly inhibited by intracellular ETX. We further show that the movement of neutral molecule ETX in the Kir2.1 channel is accompanied by ∼1.2 K(+), giving rise to the vivid voltage dependence of ETX unbinding rate. Moreover, the apparent affinity (K d ) of ETX in the channels are decreased by single-point mutations involving M183, E224, and S165, and especially by double mutations involving T141/S165, which always also disrupt the flux-coupling feature of ETX block. Molecular dynamics simulation demonstrates narrowing of the pore at ∼D172 by binding of ETX to S165 or T141. ETX block of the Kir2.1 channels may cause a modest but critical depolarization of the relevant neurons, decreasing available T-type Ca(2+) channels and consequently lessening pathological thalamocortical burst discharges.
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18
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Regionally specific expression of high-voltage-activated calcium channels in thalamic nuclei of epileptic and non-epileptic rats. Mol Cell Neurosci 2014; 61:110-22. [PMID: 24914823 DOI: 10.1016/j.mcn.2014.06.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 05/30/2014] [Accepted: 06/05/2014] [Indexed: 11/21/2022] Open
Abstract
The polygenic origin of generalized absence epilepsy results in dysfunction of ion channels that allows the switch from physiological asynchronous to pathophysiological highly synchronous network activity. Evidence from rat and mouse models of absence epilepsy indicates that altered Ca(2+) channel activity contributes to cellular and network alterations that lead to seizure activity. Under physiological circumstances, high voltage-activated (HVA) Ca(2+) channels are important in determining the thalamic firing profile. Here, we investigated a possible contribution of HVA channels to the epileptic phenotype using a rodent genetic model of absence epilepsy. In this study, HVA Ca(2+) currents were recorded from neurons of three different thalamic nuclei that are involved in both sensory signal transmission and rhythmic-synchronized activity during epileptic spike-and-wave discharges (SWD), namely the dorsal part of the lateral geniculate nucleus (dLGN), the ventrobasal thalamic complex (VB) and the reticular thalamic nucleus (NRT) of epileptic Wistar Albino Glaxo rats from Rijswijk (WAG/Rij) and non-epileptic August Copenhagen Irish (ACI) rats. HVA Ca(2+) current densities in dLGN neurons were significantly increased in epileptic rats compared with non-epileptic controls while other thalamic regions revealed no differences between the strains. Application of specific channel blockers revealed that the increased current was carried by L-type Ca(2+) channels. Electrophysiological evidence of increased L-type current correlated with up-regulated mRNA and protein expression of a particular L-type channel, namely Cav1.3, in dLGN of epileptic rats. No significant changes were found for other HVA Ca(2+) channels. Moreover, pharmacological inactivation of L-type Ca(2+) channels results in altered firing profiles of thalamocortical relay (TC) neurons from non-epileptic rather than from epileptic rats. While HVA Ca(2+) channels influence tonic and burst firing in ACI and WAG/Rij differently, it is discussed that increased Cav1.3 expression may indirectly contribute to increased robustness of burst firing and thereby the epileptic phenotype of absence epilepsy.
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19
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Chen Y, Parker WD, Wang K. The role of T-type calcium channel genes in absence seizures. Front Neurol 2014; 5:45. [PMID: 24847307 PMCID: PMC4023043 DOI: 10.3389/fneur.2014.00045] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 03/24/2014] [Indexed: 12/05/2022] Open
Abstract
The thalamic relay neurons, reticular thalamic nucleus, and neocortical pyramidal cells form a circuit that sustains oscillatory burst firing, and is regarded as the underlying mechanism of absence seizures. T-type calcium channels play a key role in this circuit. Here, we review the role of T-type calcium channel genes in the development of absence seizures, and emphasize gain or loss of function mutations, and other variations that alter both quantity and quality of transcripts, and methylation status of isoforms of T-type calcium channel proteins might be of equal importance in understanding the pathological mechanism of absence seizures.
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Affiliation(s)
- Yucai Chen
- University of Illinois at Chicago , Peoria, IL , USA
| | | | - Keling Wang
- Hebei Children Hospital , Shijiazhuang , China
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20
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Siwek ME, Müller R, Henseler C, Broich K, Papazoglou A, Weiergräber M. The CaV2.3 R-type voltage-gated Ca2+ channel in mouse sleep architecture. Sleep 2014; 37:881-92. [PMID: 24790266 DOI: 10.5665/sleep.3652] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES Voltage-gated Ca(2+) channels (VGCCs) are key elements in mediating thalamocortical rhythmicity. Low-voltage activated (LVA) CaV 3 T-type Ca(2+) channels have been related to thalamic rebound burst firing and to generation of non-rapid eye movement (NREM) sleep. High-voltage activated (HVA) CaV 1 L-type Ca(2+) channels, on the opposite, favor the tonic mode of action associated with higher levels of vigilance. However, the role of the HVA Non-L-type CaV2.3 Ca(2+) channels, which are predominantly expressed in the reticular thalamic nucleus (RTN), still remains unclear. Recently, CaV2.3(-/-) mice were reported to exhibit altered spike-wave discharge (SWD)/absence seizure susceptibility supported by the observation that CaV2.3 mediated Ca(2+) influx into RTN neurons can trigger small-conductance Ca(2+)-activated K(+)-channel type 2 (SK2) currents capable of maintaining thalamic burst activity. Based on these studies we investigated the role of CaV2.3 R-type Ca(2+) channels in rodent sleep. METHODS The role of CaV2.3 Ca(2+) channels was analyzed in CaV2.3(-/-) mice and controls in both spontaneous and artificial urethane-induced sleep, using implantable video-EEG radiotelemetry. Data were analyzed for alterations in sleep architecture using sleep staging software and time-frequency analysis. RESULTS CaV2.3 deficient mice exhibited reduced wake duration and increased slow-wave sleep (SWS). Whereas mean sleep stage durations remained unchanged, the total number of SWS epochs was increased in CaV2.3(-/-) mice. Additional changes were observed for sleep stage transitions and EEG amplitudes. Furthermore, urethane-induced SWS mimicked spontaneous sleep results obtained from CaV2.3 deficient mice. Quantitative Real-time PCR did not reveal changes in thalamic CaV3 T-type Ca(2+) channel expression. The detailed mechanisms of SWS increase in CaV2.3(-/-) mice remain to be determined. CONCLUSIONS Low-voltage activated CaV2.3 R-type Ca(2+) channels in the thalamocortical loop and extra-thalamocortical circuitries substantially regulate rodent sleep architecture thus representing a novel potential target for pharmacological treatment of sleep disorders in the future.
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Affiliation(s)
| | - Ralf Müller
- Department of Psychiatry and Psychotherapy, University of Cologne, Cologne, Germany
| | | | - Karl Broich
- Federal Institute for Drugs and Medical Devices, Bonn, BfArM, Germany
| | - Anna Papazoglou
- Federal Institute for Drugs and Medical Devices, Bonn, BfArM, Germany
| | - Marco Weiergräber
- Federal Institute for Drugs and Medical Devices, Bonn, BfArM, Germany ; Department of Psychiatry and Psychotherapy, University of Cologne, Cologne, Germany
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21
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Lee JH, Seo SH, Lim EJ, Cho NC, Nam G, Kang SB, Pae AN, Jeong N, Keum G. Synthesis and biological evaluation of 1-(isoxazol-5-ylmethylaminoethyl)-4-phenyl tetrahydropyridine and piperidine derivatives as potent T-type calcium channel blockers with antinociceptive effect in a neuropathic pain model. Eur J Med Chem 2014; 74:246-57. [DOI: 10.1016/j.ejmech.2013.12.056] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 12/20/2013] [Accepted: 12/24/2013] [Indexed: 12/11/2022]
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22
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Engbers JDT, Anderson D, Zamponi GW, Turner RW. Signal processing by T-type calcium channel interactions in the cerebellum. Front Cell Neurosci 2013; 7:230. [PMID: 24348329 PMCID: PMC3841819 DOI: 10.3389/fncel.2013.00230] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 11/06/2013] [Indexed: 01/28/2023] Open
Abstract
T-type calcium channels of the Cav3 family are unique among voltage-gated calcium channels due to their low activation voltage, rapid inactivation, and small single channel conductance. These special properties allow Cav3 calcium channels to regulate neuronal processing in the subthreshold voltage range. Here, we review two different subthreshold ion channel interactions involving Cav3 channels and explore the ability of these interactions to expand the functional roles of Cav3 channels. In cerebellar Purkinje cells, Cav3 and intermediate conductance calcium-activated potassium (IKCa) channels form a novel complex which creates a low voltage-activated, transient outward current capable of suppressing temporal summation of excitatory postsynaptic potentials (EPSPs). In large diameter neurons of the deep cerebellar nuclei, Cav3-mediated calcium current (I T) and hyperpolarization-activated cation current (I H) are activated during trains of inhibitory postsynaptic potentials. These currents have distinct, and yet synergistic, roles in the subthreshold domain with I T generating a rebound burst and I H controlling first spike latency and rebound spike precision. However, by shortening the membrane time constant the membrane returns towards resting value at a faster rate, allowing I H to increase the efficacy of I T and increase the range of burst frequencies that can be generated. The net effect of Cav3 channels thus depends on the channels with which they are paired. When expressed in a complex with a KCa channel, Cav3 channels reduce excitability when processing excitatory inputs. If functionally coupled with an HCN channel, the depolarizing effect of Cav3 channels is accentuated, allowing for efficient inversion of inhibitory inputs to generate a rebound burst output. Therefore, signal processing relies not only on the activity of individual subtypes of channels but also on complex interactions between ion channels whether based on a physical complex or by indirect effects on membrane properties.
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Affiliation(s)
- Jordan D. T. Engbers
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, University of CalgaryCalgary, Canada
| | - Dustin Anderson
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, University of CalgaryCalgary, Canada
| | - Gerald W. Zamponi
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of CalgaryCalgary, Canada
| | - Ray W. Turner
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, University of CalgaryCalgary, Canada
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of CalgaryCalgary, Canada
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Sleep spindles are generated in the absence of T-type calcium channel-mediated low-threshold burst firing of thalamocortical neurons. Proc Natl Acad Sci U S A 2013; 110:20266-71. [PMID: 24282303 DOI: 10.1073/pnas.1320572110] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
T-type Ca(2+) channels in thalamocortical (TC) neurons have long been considered to play a critical role in the genesis of sleep spindles, one of several TC oscillations. A classical model for TC oscillations states that reciprocal interaction between synaptically connected GABAergic thalamic reticular nucleus (TRN) neurons and glutamatergic TC neurons generates oscillations through T-type channel-mediated low-threshold burst firings of neurons in the two nuclei. These oscillations are then transmitted from TC neurons to cortical neurons, contributing to the network of TC oscillations. Unexpectedly, however, we found that both WT and KO mice for CaV3.1, the gene for T-type Ca(2+) channels in TC neurons, exhibit typical waxing-and-waning sleep spindle waves at a similar occurrence and with similar amplitudes and episode durations during non-rapid eye movement sleep. Single-unit recording in parallel with electroencephalography in vivo confirmed a complete lack of burst firing in the mutant TC neurons. Of particular interest, the tonic spike frequency in TC neurons was significantly increased during spindle periods compared with nonspindle periods in both genotypes. In contrast, no significant change in burst firing frequency between spindle and nonspindle periods was noted in the WT mice. Furthermore, spindle-like oscillations were readily generated within intrathalamic circuits composed solely of TRN and TC neurons in vitro in both the KO mutant and WT mice. Our findings call into question the essential role of low-threshold burst firings in TC neurons and suggest that tonic firing is important for the generation and propagation of spindle oscillations in the TC circuit.
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