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Uva L, Bruno G, de Curtis M. Activity-dependent extracellular potassium changes in unmyelinated versus myelinated areas in olfactory regions of the isolated female guinea-pig brain. Exp Neurol 2024; 379:114884. [PMID: 38992824 DOI: 10.1016/j.expneurol.2024.114884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 06/26/2024] [Accepted: 07/08/2024] [Indexed: 07/13/2024]
Abstract
The potassium released in the extracellular space during neuronal activity is rapidly removed by glia and neurons to maintain tissue homeostasis. Oligodendrocyte-derived myelin axonal coating contributes to potassium buffering and is therefore crucial to control brain excitability. We studied activity-dependent extracellular potassium ([K+]o) changes in the piriform cortex (PC), a region that features highly segregated bundles of myelinated and unmyelinated fibers. Four-aminopyridine (4AP; 50 μM) treatment or patterned high-frequency stimulations (hfST) were utilized to generate [K+]o changes measured with potassium-sensitive electrodes in the myelinated lateral olfactory tract (LOT), in the unmyelinated PC layer I and in the myelinated deep PC layers in the ex vivo isolated guinea-pig brain. Seizure-like events induced by 4AP are initiated by the abrupt [K+]o rise in the layer I formed by unmyelinated fibers (Uva et al., 2017). Larger [K+]o shifts occurred in unmyelinated layers compared to the myelinated LOT. LOT hfST that mimicks pre-seizure discharges also generated higher [K+]o changes in unmyelinated PC layer I than in LOT and deep PC layers. The treatment with the Kir4.1 potassium channel blocker BaCl2 (100 μM) enhanced the [K+]o changes generated by hfST in myelinated structures. Our data show that activity-dependent [K+]o changes are intrinsically different in myelinated vs unmyelinated cortical regions. The larger [K+]o shifts generated in unmyelinated structures may represent a vehicle for seizure generation.
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Affiliation(s)
- Laura Uva
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11/via Amadeo 42, Milano, Italy..
| | - Gaia Bruno
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11/via Amadeo 42, Milano, Italy.; Dipartimento di Biologia e Biotecnologia, via Forlanini, 6, Università di Pavia, 27100, Pavia, Italy..
| | - Marco de Curtis
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11/via Amadeo 42, Milano, Italy..
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2
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Groschup B, Calandra GM, Raitmayr C, Shrouder J, Llovera G, Zaki AG, Burgstaller S, Bischof H, Eroglu E, Liesz A, Malli R, Filser S, Plesnila N. Probing intracellular potassium dynamics in neurons with the genetically encoded sensor lc-LysM GEPII 1.0 in vitro and in vivo. Sci Rep 2024; 14:13753. [PMID: 38877089 PMCID: PMC11178854 DOI: 10.1038/s41598-024-62993-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 05/23/2024] [Indexed: 06/16/2024] Open
Abstract
Neuronal activity is accompanied by a net outflow of potassium ions (K+) from the intra- to the extracellular space. While extracellular [K+] changes during neuronal activity are well characterized, intracellular dynamics have been less well investigated due to lack of respective probes. In the current study we characterized the FRET-based K+ biosensor lc-LysM GEPII 1.0 for its capacity to measure intracellular [K+] changes in primary cultured neurons and in mouse cortical neurons in vivo. We found that lc-LysM GEPII 1.0 can resolve neuronal [K+] decreases in vitro during seizure-like and intense optogenetically evoked activity. [K+] changes during single action potentials could not be recorded. We confirmed these findings in vivo by expressing lc-LysM GEPII 1.0 in mouse cortical neurons and performing 2-photon fluorescence lifetime imaging. We observed an increase in the fluorescence lifetime of lc-LysM GEPII 1.0 during periinfarct depolarizations, which indicates a decrease in intracellular neuronal [K+]. Our findings suggest that lc-LysM GEPII 1.0 can be used to measure large changes in [K+] in neurons in vitro and in vivo but requires optimization to resolve smaller changes as observed during single action potentials.
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Affiliation(s)
- Bernhard Groschup
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, LMU Munich, Munich, Germany
- Graduate School of Systemic Neurosciences, LMU Munich, Planegg-Martinsried, Germany
| | - Gian Marco Calandra
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, LMU Munich, Munich, Germany
- Graduate School of Systemic Neurosciences, LMU Munich, Planegg-Martinsried, Germany
| | - Constanze Raitmayr
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, LMU Munich, Munich, Germany
| | - Joshua Shrouder
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, LMU Munich, Munich, Germany
| | - Gemma Llovera
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, LMU Munich, Munich, Germany
| | - Asal Ghaffari Zaki
- Regenerative and Restorative Medicine Research Center (REMER), Research Institute for Health Sciences and Technologies (SABITA), Istanbul Medipol University, Istanbul, Turkey
- Molecular Biology, Genetics and Bioengineering Program, Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul, Turkey
| | - Sandra Burgstaller
- Institut für Klinische Anatomie und Zellanalytik (Österbergstraße 3), Eberhard Karls Universität Tübingen, Tübingen, Germany
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/4, 8010, Graz, Austria
| | - Helmut Bischof
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/4, 8010, Graz, Austria
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Auf der Morgenstelle 8, 72076, Tübingen, Germany
| | - Emrah Eroglu
- Regenerative and Restorative Medicine Research Center (REMER), Research Institute for Health Sciences and Technologies (SABITA), Istanbul Medipol University, Istanbul, Turkey
- Molecular Biology, Genetics and Bioengineering Program, Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul, Turkey
| | - Arthur Liesz
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, LMU Munich, Munich, Germany
- Graduate School of Systemic Neurosciences, LMU Munich, Planegg-Martinsried, Germany
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Roland Malli
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/4, 8010, Graz, Austria
- BioTechMed-Graz, Mozartgasse 12/II, 8010, Graz, Austria
| | - Severin Filser
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, LMU Munich, Munich, Germany
- Deutsches Zentrum Für Neurodegenerative Erkrankungen (DZNE), Light Microscope Facility (LMF), Bonn, Germany
| | - Nikolaus Plesnila
- Institute for Stroke and Dementia Research (ISD), LMU University Hospital, LMU Munich, Munich, Germany.
- Graduate School of Systemic Neurosciences, LMU Munich, Planegg-Martinsried, Germany.
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Auf der Morgenstelle 8, 72076, Tübingen, Germany.
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Dossi E, Zonca L, Pivonkova H, Milior G, Moulard J, Vargova L, Chever O, Holcman D, Rouach N. Astroglial gap junctions strengthen hippocampal network activity by sustaining afterhyperpolarization via KCNQ channels. Cell Rep 2024; 43:114158. [PMID: 38722742 DOI: 10.1016/j.celrep.2024.114158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 03/01/2024] [Accepted: 04/11/2024] [Indexed: 06/01/2024] Open
Abstract
Throughout the brain, astrocytes form networks mediated by gap junction channels that promote the activity of neuronal ensembles. Although their inputs on neuronal information processing are well established, how molecular gap junction channels shape neuronal network patterns remains unclear. Here, using astroglial connexin-deficient mice, in which astrocytes are disconnected and neuronal bursting patterns are abnormal, we show that astrocyte networks strengthen bursting activity via dynamic regulation of extracellular potassium levels, independently of glutamate homeostasis or metabolic support. Using a facilitation-depression model, we identify neuronal afterhyperpolarization as the key parameter underlying bursting pattern regulation by extracellular potassium in mice with disconnected astrocytes. We confirm this prediction experimentally and reveal that astroglial network control of extracellular potassium sustains neuronal afterhyperpolarization via KCNQ voltage-gated K+ channels. Altogether, these data delineate how astroglial gap junctions mechanistically strengthen neuronal population bursts and point to approaches for controlling aberrant activity in neurological diseases.
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Affiliation(s)
- Elena Dossi
- Neuroglial Interactions in Cerebral Physiology and Pathologies, Center for Interdisciplinary Research in Biology, Collège de France, CNRS, INSERM, Labex Memolife, Université PSL, Paris, France
| | - Lou Zonca
- Group of Data Modeling and Computational Biology, Institute of Biology, Ecole Normale Superieure, CNRS, INSERM, Université PSL, Paris, France; ED386, Ecole Doctorale de Sciences Mathématiques Paris Centre, Paris, France
| | - Helena Pivonkova
- Neuroglial Interactions in Cerebral Physiology and Pathologies, Center for Interdisciplinary Research in Biology, Collège de France, CNRS, INSERM, Labex Memolife, Université PSL, Paris, France; Department of Cellular Neurophysiology, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czech Republic; 2(nd) Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Giampaolo Milior
- Neuroglial Interactions in Cerebral Physiology and Pathologies, Center for Interdisciplinary Research in Biology, Collège de France, CNRS, INSERM, Labex Memolife, Université PSL, Paris, France
| | - Julien Moulard
- Neuroglial Interactions in Cerebral Physiology and Pathologies, Center for Interdisciplinary Research in Biology, Collège de France, CNRS, INSERM, Labex Memolife, Université PSL, Paris, France
| | - Lydia Vargova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czech Republic; 2(nd) Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Oana Chever
- Neuroglial Interactions in Cerebral Physiology and Pathologies, Center for Interdisciplinary Research in Biology, Collège de France, CNRS, INSERM, Labex Memolife, Université PSL, Paris, France
| | - David Holcman
- Group of Data Modeling and Computational Biology, Institute of Biology, Ecole Normale Superieure, CNRS, INSERM, Université PSL, Paris, France.
| | - Nathalie Rouach
- Neuroglial Interactions in Cerebral Physiology and Pathologies, Center for Interdisciplinary Research in Biology, Collège de France, CNRS, INSERM, Labex Memolife, Université PSL, Paris, France.
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Wendling F, Koksal-Ersoz E, Al-Harrach M, Yochum M, Merlet I, Ruffini G, Bartolomei F, Benquet P. Multiscale neuro-inspired models for interpretation of EEG signals in patients with epilepsy. Clin Neurophysiol 2024; 161:198-210. [PMID: 38520800 DOI: 10.1016/j.clinph.2024.03.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 03/06/2024] [Accepted: 03/11/2024] [Indexed: 03/25/2024]
Abstract
OBJECTIVE The aim is to gain insight into the pathophysiological mechanisms underlying interictal epileptiform discharges observed in electroencephalographic (EEG) and stereo-EEG (SEEG, depth electrodes) recordings performed during pre-surgical evaluation of patients with drug-resistant epilepsy. METHODS We developed novel neuro-inspired computational models of the human cerebral cortex at three different levels of description: i) microscale (detailed neuron models), ii) mesoscale (neuronal mass models) and iii) macroscale (whole brain models). Although conceptually different, micro- and mesoscale models share some similar features, such as the typology of neurons (pyramidal cells and three types of interneurons), their spatial arrangement in cortical layers, and their synaptic connectivity (excitatory and inhibitory). The whole brain model consists of a large-scale network of interconnected neuronal masses, with connectivity based on the human connectome. RESULTS For these three levels of description, the fine-tuning of free parameters and the quantitative comparison with real data allowed us to reproduce interictal epileptiform discharges with a high degree of fidelity and to formulate hypotheses about the cell- and network-related mechanisms underlying the generation of fast ripples and SEEG-recorded epileptic spikes and spike-waves. CONCLUSIONS The proposed models provide valuable insights into the pathophysiological mechanisms underlying the generation of epileptic events. The knowledge gained from these models effectively complements the clinical analysis of SEEG data collected during the evaluation of patients with epilepsy. SIGNIFICANCE These models are likely to play a key role in the mechanistic interpretation of epileptiform activity.
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Affiliation(s)
| | | | | | | | | | | | - Fabrice Bartolomei
- APHM, Timone Hospital, Epileptology and Cerebral Rhythmology Department, Marseille, France; Univ Aix Marseille, INSERM, INS, Inst Neurosci Syst, Marseille, France
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5
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Wenzel M, Huberfeld G, Grayden DB, de Curtis M, Trevelyan AJ. A debate on the neuronal origin of focal seizures. Epilepsia 2023; 64 Suppl 3:S37-S48. [PMID: 37183507 DOI: 10.1111/epi.17650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 04/26/2023] [Accepted: 05/12/2023] [Indexed: 05/16/2023]
Abstract
A critical question regarding how focal seizures start is whether we can identify particular cell classes that drive the pathological process. This was the topic for debate at the recent International Conference for Technology and Analysis of Seizures (ICTALS) meeting (July 2022, Bern, CH) that we summarize here. The debate has been fueled in recent times by the introduction of powerful new ways to manipulate subpopulations of cells in relative isolation, mostly using optogenetics. The motivation for resolving the debate is to identify novel targets for therapeutic interventions through a deeper understanding of the etiology of seizures.
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Affiliation(s)
- Michael Wenzel
- Department of Epileptology, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Gilles Huberfeld
- Neurology Department, Hopital Fondation Adolphe de Rothschild, Paris, France
- Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS, INSERM, Université PSL, Paris, France
| | - David B Grayden
- Department of Biomedical Engineering, The University of Melbourne, Melbourne, Victoria, Australia
- Department of Medicine, St Vincent's Hospital, The University of Melbourne, Melbourne, Victoria, Australia
- Graeme Clark Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Marco de Curtis
- Epilepsy Unit, Fondazione I.R.C.C.S., Istituto Neurologico Carlo Besta, Milan, Italy
| | - Andrew J Trevelyan
- Newcastle University Biosciences Institute, Medical School, Framlington Place, Newcastle upon Tyne, UK
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6
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Graham RT, Parrish RR, Alberio L, Johnson EL, Owens L, Trevelyan AJ. Optogenetic stimulation reveals a latent tipping point in cortical networks during ictogenesis. Brain 2023; 146:2814-2827. [PMID: 36572952 PMCID: PMC10316782 DOI: 10.1093/brain/awac487] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Revised: 11/17/2022] [Accepted: 12/06/2022] [Indexed: 12/28/2022] Open
Abstract
Brain-state transitions are readily apparent from changes in brain rhythms,1 but are difficult to predict, suggestive that the underlying cause is latent to passive recording methods. Among the most important transitions, clinically, are the starts of seizures. We here show that an 'active probing' approach may have several important benefits for epileptic management, including by helping predict these transitions. We used mice expressing the optogenetic actuator, channelrhodopsin, in pyramidal cells, allowing this population to be stimulated in isolation. Intermittent stimulation at frequencies as low as 0.033 Hz (period = 30 s) delayed the onset of seizure-like events in an acute brain slice model of ictogenesis, but the effect was lost if stimulation was delivered at even lower frequencies (1/min). Notably, active probing additionally provides advance indication of when seizure-like activity is imminent, revealed by monitoring the postsynaptic response to stimulation. The postsynaptic response, recorded extracellularly, showed an all-or-nothing change in both amplitude and duration, a few hundred seconds before seizure-like activity began-a sufficient length of time to provide a helpful warning of an impending seizure. The change in the postsynaptic response then persisted for the remainder of the recording, indicative of a state change from a pre-epileptic to a pro-epileptic network. This occurred in parallel with a large increase in the stimulation-triggered Ca2+ entry into pyramidal dendrites, and a step increase in the number of evoked postsynaptic action potentials, both consistent with a reduction in the threshold for dendritic action potentials. In 0 Mg2+ bathing media, the reduced threshold was not associated with changes in glutamatergic synaptic function, nor of GABAergic release from either parvalbumin or somatostatin interneurons, but simulations indicate that the step change in the optogenetic response can instead arise from incremental increases in intracellular [Cl-]. The change in the response to stimulation was replicated by artificially raising intracellular [Cl-], using the optogenetic chloride pump, halorhodopsin. By contrast, increases in extracellular [K+] cannot account for the firing patterns in the response to stimulation, although this, and other cellular changes, may contribute to ictal initiation in other circumstances. We describe how these various cellular changes form a synergistic network of positive feedback mechanisms, which may explain the precipitous nature of seizure onset. This model of seizure initiation draws together several major lines of epilepsy research as well as providing an important proof-of-principle regarding the utility of open-loop brain stimulation for clinical management of the condition.
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Affiliation(s)
- Robert T Graham
- Medical School, Newcastle University Biosciences Institute, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - R Ryley Parrish
- Medical School, Newcastle University Biosciences Institute, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - Laura Alberio
- Medical School, Newcastle University Biosciences Institute, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - Emily L Johnson
- Medical School, Newcastle University Biosciences Institute, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - Laura Owens
- Medical School, Newcastle University Biosciences Institute, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - Andrew J Trevelyan
- Medical School, Newcastle University Biosciences Institute, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
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7
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Bussaka S, Suehiro T, Mitsuiki K, Morioka T, Shono T, Fujiki F, Nakano T. Non-convulsive status epilepticus possibly induced by a rapid correction of severe hyperkalemia: a case report and literature review. BMC Nephrol 2023; 24:93. [PMID: 37038101 PMCID: PMC10084670 DOI: 10.1186/s12882-023-03141-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 03/24/2023] [Indexed: 04/12/2023] Open
Abstract
BACKGROUND Patients with chronic kidney disease frequently develop neurological complications including confusion and altered consciousness. Non-convulsive status epilepticus, which is characterized by a change in behavior and/or mental process accompanied by epileptiform discharges on electroencephalogram in the absence of convulsive seizures, is one of the overlooked causes of altered consciousness. The incidence and precise pathophysiological mechanism of non-convulsive status epilepticus in patients with kidney disease, and especially in patients with electrolyte disturbances, remains unknown. We recently treated an older patient with chronic kidney disease and severe hyperkalemia in whom non-convulsive status epilepticus developed following a correction of severe hyperkalemia. CASE PRESENTATION An 82-year-old male was admitted to our hospital at midnight because of weakness of all four limbs (Day 1). He underwent urgent hemodialysis for severe hyperkalemia (9.84 mEq/L) and his serum potassium concentration decreased to 4.97 mEq/L. He regained full consciousness and his limb weakness improved on the morning of Day 2, but he became confused in the evening. Electroencephalogram revealed repeated low-voltage ictal discharges in the right occipital region and a diagnosis of non-convulsive status epilepticus was made. Following medication with fosphenytoin and phenytoin, the patient became fully alert and orientated on Day 8. CONCLUSION We speculate that a rapid correction of hyperkalemia was the possible cause of non-convulsive status epilepticus development. To our knowledge, this is the first report of non-convulsive status epilepticus from a potassium abnormality. We described a case of this condition in detail and summarized 78 previous case reports of non-convulsive status epilepticus with kidney disease or electrolyte disturbances.
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Affiliation(s)
- Saki Bussaka
- Department of Nephrology, Harasanshin Hospital, 1-8, Taihakumachi, Hakata-Ku, Fukuoka, Fukuoka, 812-0033, Japan
| | - Takaichi Suehiro
- Department of Nephrology, Harasanshin Hospital, 1-8, Taihakumachi, Hakata-Ku, Fukuoka, Fukuoka, 812-0033, Japan.
| | - Koji Mitsuiki
- Department of Nephrology, Harasanshin Hospital, 1-8, Taihakumachi, Hakata-Ku, Fukuoka, Fukuoka, 812-0033, Japan
| | - Takato Morioka
- Department of Neurosurgery, Harasanshin Hospital, Fukuoka, Japan
| | - Tadahisa Shono
- Department of Neurosurgery, Harasanshin Hospital, Fukuoka, Japan
| | - Fujio Fujiki
- Department of Neurology, Harasanshin Hospital, Fukuoka, Japan
| | - Toshiaki Nakano
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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8
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Curry RN, Aiba I, Meyer J, Lozzi B, Ko Y, McDonald MF, Rosenbaum A, Cervantes A, Huang-Hobbs E, Cocito C, Greenfield JP, Jalali A, Gavvala J, Mohila C, Serin Harmanci A, Noebels J, Rao G, Deneen B. Glioma epileptiform activity and progression are driven by IGSF3-mediated potassium dysregulation. Neuron 2023; 111:682-695.e9. [PMID: 36787748 PMCID: PMC9991983 DOI: 10.1016/j.neuron.2023.01.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/11/2022] [Accepted: 01/17/2023] [Indexed: 02/15/2023]
Abstract
Seizures are a frequent pathophysiological feature of malignant glioma. Recent studies implicate peritumoral synaptic dysregulation as a driver of brain hyperactivity and tumor progression; however, the molecular mechanisms that govern these phenomena remain elusive. Using scRNA-seq and intraoperative patient ECoG recordings, we show that tumors from seizure patients are enriched for gene signatures regulating synapse formation. Employing a human-to-mouse in vivo functionalization pipeline to screen these genes, we identify IGSF3 as a mediator of glioma progression and dysregulated neural circuitry that manifests as spreading depolarization (SD). Mechanistically, we discover that IGSF3 interacts with Kir4.1 to suppress potassium buffering and found that seizure patients exhibit reduced expression of potassium handlers in proliferating tumor cells. In vivo imaging reveals that dysregulated synaptic activity emanates from the tumor-neuron interface, which we confirm in patients. Our studies reveal that tumor progression and seizures are enabled by ion dyshomeostasis and identify SD as a driver of disease.
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Affiliation(s)
- Rachel Naomi Curry
- The Integrative Molecular and Biomedical Sciences Graduate Program, Baylor College of Medicine, Houston, TX 77030, USA; Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA; Center for Cancer Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Isamu Aiba
- Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jochen Meyer
- Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Brittney Lozzi
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA; Center for Cancer Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Program in Genetics and Genomics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Yeunjung Ko
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA; Center for Cancer Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Program in Immunology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Malcolm Ford McDonald
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA; Center for Cancer Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Program in Development, Disease, Models, and Therapeutics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Anna Rosenbaum
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA; Center for Cancer Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Alexis Cervantes
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA; Center for Cancer Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Emmet Huang-Hobbs
- The Integrative Molecular and Biomedical Sciences Graduate Program, Baylor College of Medicine, Houston, TX 77030, USA; Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA; Center for Cancer Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Carolina Cocito
- Department of Pediatric Neurological Surgery, Weill Cornell Medicine, New York, NY 10065, USA
| | | | - Ali Jalali
- Center for Cancer Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neurosurgery, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jay Gavvala
- Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Carrie Mohila
- Department of Pathology, Texas Children's Hospital, Houston, TX 77030, USA
| | - Akdes Serin Harmanci
- Center for Cancer Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neurosurgery, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jeffrey Noebels
- Center for Cancer Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ganesh Rao
- Center for Cancer Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neurosurgery, Baylor College of Medicine, Houston, TX 77030, USA
| | - Benjamin Deneen
- The Integrative Molecular and Biomedical Sciences Graduate Program, Baylor College of Medicine, Houston, TX 77030, USA; Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA; Center for Cancer Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Program in Development, Disease, Models, and Therapeutics, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neurosurgery, Baylor College of Medicine, Houston, TX 77030, USA.
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9
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Activity-Dependent Fluctuations in Interstitial [K +]: Investigations Using Ion-Sensitive Microelectrodes. MOLECULES (BASEL, SWITZERLAND) 2023; 28:molecules28020523. [PMID: 36677581 PMCID: PMC9865121 DOI: 10.3390/molecules28020523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/31/2022] [Accepted: 01/02/2023] [Indexed: 01/06/2023]
Abstract
In the course of action potential firing, all axons and neurons release K+ from the intra- cellular compartment into the interstitial space to counteract the depolarizing effect of Na+ influx, which restores the resting membrane potential. This efflux of K+ from axons results in K+ accumulation in the interstitial space, causing depolarization of the K+ reversal potential (EK), which can prevent subsequent action potentials. To ensure optimal neuronal function, the K+ is buffered by astrocytes, an energy-dependent process, which acts as a sink for interstitial K+, absorbing it at regions of high concentration and distributing it through the syncytium for release in distant regions. Pathological processes in which energy production is compromised, such as anoxia, ischemia, epilepsy and spreading depression, can lead to excessive interstitial K+ accumulation, disrupting sensitive trans-membrane ion gradients and attenuating neuronal activity. The changes that occur in interstitial [K+] resulting from both physiological and pathological processes can be monitored accurately in real time using K+-sensitive microelectrodes, an invaluable tool in electrophysiological studies.
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10
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Kinboshi M. [Studying abroad for epilepsy basic research during the COVID-19 pandemic]. Rinsho Shinkeigaku 2023; 63:105-107. [PMID: 36843023 DOI: 10.5692/clinicalneurol.63_2_studyabroad1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
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11
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Proskurina EY, Chizhov AV, Zaitsev AV. Optogenetic Low-Frequency Stimulation of Principal Neurons, but Not Parvalbumin-Positive Interneurons, Prevents Generation of Ictal Discharges in Rodent Entorhinal Cortex in an In Vitro 4-Aminopyridine Model. Int J Mol Sci 2022; 24:ijms24010195. [PMID: 36613660 PMCID: PMC9820186 DOI: 10.3390/ijms24010195] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/17/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022] Open
Abstract
Low-frequency electrical stimulation is used to treat some drug-resistant forms of epilepsy. Despite the effectiveness of the method in suppressing seizures, there is a considerable risk of side effects. An optogenetic approach allows the targeting of specific populations of neurons, which can increase the effectiveness and safety of low-frequency stimulation. In our study, we tested the efficacy of the suppression of ictal activity in entorhinal cortex slices in a 4-aminopyridine model with three variants of low-frequency light stimulation (LFLS): (1) activation of excitatory and inhibitory neurons (on Thy1-ChR2-YFP mice), (2) activation of inhibitory interneurons only (on PV-Cre mice after virus injection with channelrhodopsin2 gene), and (3) hyperpolarization of excitatory neurons (on Wistar rats after virus injection with archaerhodopsin gene). Only in the first variant did simultaneous LFLS of excitatory and inhibitory neurons replace ictal activity with interictal activity. We suggest that LFLS caused changes in the concentration gradients of K+ and Na+ cations across the neuron membrane, which activated Na-K pumping. According to the mathematical modeling, the increase in Na-K pump activity in neurons induced by LFLS led to an antiepileptic effect. Thus, a less specific and generalized optogenetic effect on entorhinal cortex neurons was more effective in suppressing ictal activity in the 4-aminopyridine model.
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Affiliation(s)
- Elena Y. Proskurina
- Almazov National Medical Research Centre, 2 Akkuratova Street, 197341 St. Petersburg, Russia
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, 44 Toreza Prospekt, 194223 St. Petersburg, Russia
| | - Anton V. Chizhov
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, 44 Toreza Prospekt, 194223 St. Petersburg, Russia
- Computational Physics Laboratory, Ioffe Institute, 26 Polytekhnicheskaya Street, 194021 St. Petersburg, Russia
- MathNeuro Team, Inria Centre at Universite Cote d’Azur, 06902 Sophia Antipolis, France
| | - Aleksey V. Zaitsev
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, 44 Toreza Prospekt, 194223 St. Petersburg, Russia
- Correspondence:
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12
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Proskurina EY, Zaitsev AV. Regulation of Potassium and Chloride Concentrations in Nervous Tissue as a Method of Anticonvulsant Therapy. J EVOL BIOCHEM PHYS+ 2022. [DOI: 10.1134/s0022093022050015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Abstract
Under some pathological conditions, such as pharmacoresistant
epilepsy, status epilepticus or certain forms of genetic abnormalities,
spiking activity of GABAergic interneurons may enhance excitation
processes in neuronal circuits and provoke the generation of ictal
discharges. As a result, anticonvulsants acting on the GABAergic
system may be ineffective or even increase seizure activity. This
paradoxical effect of the inhibitory system is due to ionic imbalances
in nervous tissue. This review addresses the mechanisms of ictal
discharge initiation in neuronal networks due to the imbalance of
chloride and potassium ions, as well as possible ways to regulate
ionic concentrations. Both the enhancement (or attenuation) of the
activity of certain neuronal ion transporters and ion pumps and
their additional expression via gene therapy can be effective in
suppressing seizure activity caused by ionic imbalances. The Na+–K+-pump,
NKCC1 and KCC2 cotransporters are important for maintaining proper
K+ and Cl– concentrations
in nervous tissue, having been repeatedly considered as pharmacological
targets for antiepileptic exposures. Further progress in this direction
is hampered by the lack of sufficiently selective pharmacological
tools and methods for providing effective drug delivery to the epileptic
focus. The use of the gene therapy techniques, such as overexpressing
of the KCC2 transporter in the epileptic focus, seems to be a more promising
approach. Another possible direction could be the use of optogenetic
tools, namely specially designed light-activated ion pumps or ion
channels. In this case, photon energy can be used to create the
required gradients of chloride and potassium ions, although these
methods also have significant limitations which complicate their
rapid introduction into medicine.
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13
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Gentiletti D, de Curtis M, Gnatkovsky V, Suffczynski P. Focal seizures are organized by feedback between neural activity and ion concentration changes. eLife 2022; 11:68541. [PMID: 35916367 PMCID: PMC9377802 DOI: 10.7554/elife.68541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 07/12/2022] [Indexed: 11/13/2022] Open
Abstract
Human and animal EEG data demonstrate that focal seizures start with low-voltage fast activity, evolve into rhythmic burst discharges and are followed by a period of suppressed background activity. This suggests that processes with dynamics in the range of tens of seconds govern focal seizure evolution. We investigate the processes associated with seizure dynamics by complementing the Hodgkin-Huxley mathematical model with the physical laws that dictate ion movement and maintain ionic gradients. Our biophysically realistic computational model closely replicates the electrographic pattern of a typical human focal seizure characterized by low voltage fast activity onset, tonic phase, clonic phase and postictal suppression. Our study demonstrates, for the first time in silico, the potential mechanism of seizure initiation by inhibitory interneurons via the initial build-up of extracellular K+ due to intense interneuronal spiking. The model also identifies ionic mechanisms that may underlie a key feature in seizure dynamics, i.e., progressive slowing down of ictal discharges towards the end of seizure. Our model prediction of specific scaling of inter-burst intervals is confirmed by seizure data recorded in the whole guinea pig brain in vitro and in humans, suggesting that the observed termination pattern may hold across different species. Our results emphasize ionic dynamics as elementary processes behind seizure generation and indicate targets for new therapeutic strategies.
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14
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Rienecker KDA, Poston RG, Segales JS, Finholm IW, Sono MH, Munteanu SJ, Ghaninejad-Esfahani M, Rejepova A, Tejeda-Garibay S, Wickman K, Marron Fernandez de Velasco E, Thayer SA, Saha RN. Mild membrane depolarization in neurons induces immediate early gene transcription and acutely subdues responses to successive stimulus. J Biol Chem 2022; 298:102278. [PMID: 35863435 PMCID: PMC9396413 DOI: 10.1016/j.jbc.2022.102278] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Revised: 07/12/2022] [Accepted: 07/13/2022] [Indexed: 11/22/2022] Open
Abstract
Immediate early genes (IEGs) are transcribed in response to neuronal activity from sensory stimulation during multiple adaptive processes in the brain. The transcriptional profile of IEGs is indicative of the duration of neuronal activity, but its sensitivity to the strength of depolarization remains unknown. Also unknown is whether activity history of graded potential changes influence future neuronal activity. In this work with dissociated rat cortical neurons, we found that mild depolarization—mediated by elevated extracellular potassium (K+)—induces a wide array of rapid IEGs and transiently depresses transcriptional and signaling responses to a successive stimulus. This latter effect was independent of de novo transcription, translation, and signaling via calcineurin or mitogen-activated protein kinase. Furthermore, as measured by multiple electrode arrays and calcium imaging, mild depolarization acutely subdues subsequent spontaneous and bicuculline-evoked activity via calcium- and N-methyl-d-aspartate receptor–dependent mechanisms. Collectively, this work suggests that a recent history of graded potential changes acutely depress neuronal intrinsic properties and subsequent responses. Such effects may have several potential downstream implications, including reducing signal-to-noise ratio during synaptic plasticity processes.
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Affiliation(s)
- Kira D A Rienecker
- Molecular and Cell Biology Department, School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, California, USA, 95343
| | - Robert G Poston
- Molecular and Cell Biology Department, School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, California, USA, 95343
| | - Joshua S Segales
- Molecular and Cell Biology Department, School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, California, USA, 95343
| | - Isabelle W Finholm
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, MN, 55455, USA
| | - Morgan H Sono
- Molecular and Cell Biology Department, School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, California, USA, 95343
| | - Sorina J Munteanu
- Molecular and Cell Biology Department, School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, California, USA, 95343
| | - Mina Ghaninejad-Esfahani
- Molecular and Cell Biology Department, School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, California, USA, 95343
| | - Ayna Rejepova
- Molecular and Cell Biology Department, School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, California, USA, 95343
| | - Susana Tejeda-Garibay
- Molecular and Cell Biology Department, School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, California, USA, 95343
| | - Kevin Wickman
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, MN, 55455, USA
| | | | - Stanley A Thayer
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, MN, 55455, USA
| | - Ramendra N Saha
- Molecular and Cell Biology Department, School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, California, USA, 95343.
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15
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Reply to “Slow oscillations anticipate interictal epileptic discharges”. Clin Neurophysiol 2022; 139:130-131. [DOI: 10.1016/j.clinph.2022.04.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Accepted: 04/19/2022] [Indexed: 11/22/2022]
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16
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A unified physiological framework of transitions between seizures, sustained ictal activity and depolarization block at the single neuron level. J Comput Neurosci 2022; 50:33-49. [PMID: 35031915 PMCID: PMC8818009 DOI: 10.1007/s10827-022-00811-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 11/10/2021] [Accepted: 01/03/2022] [Indexed: 10/29/2022]
Abstract
The majority of seizures recorded in humans and experimental animal models can be described by a generic phenomenological mathematical model, the Epileptor. In this model, seizure-like events (SLEs) are driven by a slow variable and occur via saddle node (SN) and homoclinic bifurcations at seizure onset and offset, respectively. Here we investigated SLEs at the single cell level using a biophysically relevant neuron model including a slow/fast system of four equations. The two equations for the slow subsystem describe ion concentration variations and the two equations of the fast subsystem delineate the electrophysiological activities of the neuron. Using extracellular K+ as a slow variable, we report that SLEs with SN/homoclinic bifurcations can readily occur at the single cell level when extracellular K+ reaches a critical value. In patients and experimental models, seizures can also evolve into sustained ictal activity (SIA) and depolarization block (DB), activities which are also parts of the dynamic repertoire of the Epileptor. Increasing extracellular concentration of K+ in the model to values found during experimental status epilepticus and DB, we show that SIA and DB can also occur at the single cell level. Thus, seizures, SIA, and DB, which have been first identified as network events, can exist in a unified framework of a biophysical model at the single neuron level and exhibit similar dynamics as observed in the Epileptor.Author Summary: Epilepsy is a neurological disorder characterized by the occurrence of seizures. Seizures have been characterized in patients in experimental models at both macroscopic and microscopic scales using electrophysiological recordings. Experimental works allowed the establishment of a detailed taxonomy of seizures, which can be described by mathematical models. We can distinguish two main types of models. Phenomenological (generic) models have few parameters and variables and permit detailed dynamical studies often capturing a majority of activities observed in experimental conditions. But they also have abstract parameters, making biological interpretation difficult. Biophysical models, on the other hand, use a large number of variables and parameters due to the complexity of the biological systems they represent. Because of the multiplicity of solutions, it is difficult to extract general dynamical rules. In the present work, we integrate both approaches and reduce a detailed biophysical model to sufficiently low-dimensional equations, and thus maintaining the advantages of a generic model. We propose, at the single cell level, a unified framework of different pathological activities that are seizures, depolarization block, and sustained ictal activity.
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17
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Burgstaller S, Bischof H, Rauter T, Schmidt T, Schindl R, Patz S, Groschup B, Filser S, van den Boom L, Sasse P, Lukowski R, Plesnila N, Graier WF, Malli R. Immobilization of Recombinant Fluorescent Biosensors Permits Imaging of Extracellular Ion Signals. ACS Sens 2021; 6:3994-4000. [PMID: 34752056 PMCID: PMC8630794 DOI: 10.1021/acssensors.1c01369] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
![]()
Given the importance
of ion gradients and fluxes in biology, monitoring
ions locally at the exterior of the plasma membrane of intact cells
in a noninvasive manner is highly desirable but challenging. Classical
targeting of genetically encoded biosensors at the exterior of cell
surfaces would be a suitable approach; however, it often leads to
intracellular accumulation of the tools in vesicular structures and
adverse modifications, possibly impairing sensor functionality. To
tackle these issues, we generated recombinant fluorescent ion biosensors
fused to traptavidin (TAv) specifically coupled to a biotinylated
AviTag expressed on the outer cell surface of cells. We show that
purified chimeras of TAv and pH-Lemon or GEPII 1.0, Förster
resonance energy transfer-based pH and K+ biosensors, can
be immobilized directly and specifically on biotinylated surfaces
including glass platelets and intact cells, thereby remaining fully
functional for imaging of ion dynamics. The immobilization of recombinant
TAv–GEPII 1.0 on the extracellular cell surface of primary
cortical rat neurons allowed imaging of excitotoxic glutamate-induced
K+ efflux in vitro. We also performed micropatterning of
purified TAv biosensors using a microperfusion system to generate
spatially separated TAv–pH-Lemon and TAv–GEPII 1.0 spots
for simultaneous pH and K+ measurements on cell surfaces.
Our results suggest that the approach can be greatly expanded by immobilizing
various biosensors on extracellular surfaces to quantitatively visualize
microenvironmental transport and signaling processes in different
cell culture models and other experimental settings.
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Affiliation(s)
- Sandra Burgstaller
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, Graz 8010, Austria
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, Eberhard Karls University of Tuebingen, Auf der Morgenstelle 8, Tuebingen 72076, Germany
- NMI Natural and Medical Sciences Institute at the University of Tuebingen, Reutlingen 72770, Germany
| | - Helmut Bischof
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, Graz 8010, Austria
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, Eberhard Karls University of Tuebingen, Auf der Morgenstelle 8, Tuebingen 72076, Germany
| | - Thomas Rauter
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, Graz 8010, Austria
| | - Tony Schmidt
- Gottfried Schatz Research Center, Biophysics, Medical University of Graz, Neue Stiftingtalstraße 6/6, Graz 8010, Austria
| | - Rainer Schindl
- Gottfried Schatz Research Center, Biophysics, Medical University of Graz, Neue Stiftingtalstraße 6/6, Graz 8010, Austria
| | - Silke Patz
- Department of Neurosurgery, Medical University of Graz, Auenbruggerplatz 29, Graz 8036, Austria
| | - Bernhard Groschup
- Laboratory of Experimental Stroke Research, Institute for Stroke and Dementia Research, University of Munich Medical Center, Munich 81377, Germany
| | - Severin Filser
- Laboratory of Experimental Stroke Research, Institute for Stroke and Dementia Research, University of Munich Medical Center, Munich 81377, Germany
| | - Lucas van den Boom
- Institute of Physiology I, Medical Faculty, University of Bonn, Bonn 53127, Germany
| | - Philipp Sasse
- Institute of Physiology I, Medical Faculty, University of Bonn, Bonn 53127, Germany
| | - Robert Lukowski
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, Eberhard Karls University of Tuebingen, Auf der Morgenstelle 8, Tuebingen 72076, Germany
| | - Nikolaus Plesnila
- Laboratory of Experimental Stroke Research, Institute for Stroke and Dementia Research, University of Munich Medical Center, Munich 81377, Germany
- Munich Cluster for Systems Neurology (SyNergy), Feodor-Lynen-Str. 17, Munich 81377, Germany
| | - Wolfgang F. Graier
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, Graz 8010, Austria
- BioTechMed Graz, Mozartgasse 12/II, Graz 8010, Austria
| | - Roland Malli
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, Graz 8010, Austria
- BioTechMed Graz, Mozartgasse 12/II, Graz 8010, Austria
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18
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Liu H, Tufa U, Zahra A, Chow J, Sivanenthiran N, Cheng C, Liu Y, Cheung P, Lim S, Jin Y, Mao M, Sun Y, Wu C, Wennberg R, Bardakjian B, Carlen PL, Eubanks JH, Song H, Zhang L. Electrographic Features of Spontaneous Recurrent Seizures in a Mouse Model of Extended Hippocampal Kindling. Cereb Cortex Commun 2021; 2:tgab004. [PMID: 34296153 PMCID: PMC8152854 DOI: 10.1093/texcom/tgab004] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 01/08/2021] [Accepted: 01/13/2021] [Indexed: 01/14/2023] Open
Abstract
Epilepsy is a chronic neurological disorder characterized by spontaneous recurrent seizures (SRS) and comorbidities. Kindling through repetitive brief stimulation of a limbic structure is a commonly used model of temporal lobe epilepsy. Particularly, extended kindling over a period up to a few months can induce SRS, which may simulate slowly evolving epileptogenesis of temporal lobe epilepsy. Currently, electroencephalographic (EEG) features of SRS in rodent models of extended kindling remain to be detailed. We explored this using a mouse model of extended hippocampal kindling. Intracranial EEG recordings were made from the kindled hippocampus and unstimulated hippocampal, neocortical, piriform, entorhinal, or thalamic area in individual mice. Spontaneous EEG discharges with concurrent low-voltage fast onsets were observed from the two corresponding areas in nearly all SRS detected, irrespective of associated motor seizures. Examined in brain slices, epileptiform discharges were induced by alkaline artificial cerebrospinal fluid in the hippocampal CA3, piriform and entorhinal cortical areas of extended kindled mice but not control mice. Together, these in vivo and in vitro observations suggest that the epileptic activity involving a macroscopic network may generate concurrent discharges in forebrain areas and initiate SRS in hippocampally kindled mice.
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Affiliation(s)
- Haiyu Liu
- Departments of Neurosurgery, The First Hospital of Jilin University, Changchun, Jilin 130021 China.,Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Uilki Tufa
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8.,Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario M5S 3H5, Canada
| | - Anya Zahra
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Jonathan Chow
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Nila Sivanenthiran
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Chloe Cheng
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Yapg Liu
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Phinehas Cheung
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Stellar Lim
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Yaozhong Jin
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Min Mao
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Yuqing Sun
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Chiping Wu
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Richard Wennberg
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8.,Department of Medicine, University of Toronto, Toronto, Ontario M2K 1E2, Canada
| | - Berj Bardakjian
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario M5S 3H5, Canada
| | - Peter L Carlen
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8.,Department of Medicine, University of Toronto, Toronto, Ontario M2K 1E2, Canada.,Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - James H Eubanks
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8.,Department of Surgery, University of Toronto, Toronto, Ontario M5G 1X5, Canada
| | - Hongmei Song
- Departments of Neurosurgery, The First Hospital of Jilin University, Changchun, Jilin 130021 China.,Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8
| | - Liang Zhang
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada M5T 2S8.,Department of Medicine, University of Toronto, Toronto, Ontario M2K 1E2, Canada
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19
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Exacerbation of Epilepsy by Astrocyte Alkalization and Gap Junction Uncoupling. J Neurosci 2021; 41:2106-2118. [PMID: 33478985 DOI: 10.1523/jneurosci.2365-20.2020] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/02/2020] [Accepted: 11/25/2020] [Indexed: 12/12/2022] Open
Abstract
Seizures invite seizures. At the initial stage of epilepsy, seizures intensify with each episode; however, the mechanisms underlying this exacerbation remain to be solved. Astrocytes have a strong control over neuronal excitability and the mode of information processing. This control is accomplished by adjusting the levels of various ions in the extracellular space. The network of astrocytes connected via gap junctions allows a wider or more confined distribution of these ions depending on the open probability of the gap junctions. K+ clearance relies on the K+ uptake by astrocytes and the subsequent diffusion of K+ through the astrocyte network. When astrocytes become uncoupled, K+ clearance becomes hindered. Accumulation of extracellular K+ leads to hyperexcitability of neurons. Here, using acute hippocampal slices from mice, we uncovered that brief periods of epileptiform activity result in gap junction uncoupling. In slices that experienced short-term epileptiform activity, extracellular K+ transients in response to glutamate became prolonged. Na+ imaging with a fluorescent indicator indicated that intercellular diffusion of small cations in the astrocytic syncytium via gap junctions became rapidly restricted after epileptiform activity. Using a transgenic mouse with astrocyte-specific expression of a pH sensor (Lck-E2GFP), we confirmed that astrocytes react to epileptiform activity with intracellular alkalization. Application of Na+/HCO3 - cotransporter blocker led to the suppression of intracellular alkalization of astrocytes and to the prevention of astrocyte uncoupling and hyperactivity intensification both in vitro and in vivo Therefore, the inhibition of astrocyte alkalization could become a promising therapeutic strategy for countering epilepsy development.SIGNIFICANCE STATEMENT We aimed to understand the mechanisms underlying the plastic change of forebrain circuits associated with the intensification of epilepsy. Here, we demonstrate that first-time exposure to only brief periods of epileptiform activity results in acute disturbance of the intercellular astrocyte network formed by gap junctions in hippocampal tissue slices from mice. Moreover, rapid clearance of K+ from the extracellular space was impaired. Epileptiform activity activated inward Na+/HCO3 - cotransport in astrocytes by cell depolarization, resulting in their alkalization. Our data suggest that alkaline pH shifts in astrocytes lead to gap junction uncoupling, hampering K+ clearance, and thereby to exacerbation of epilepsy. Pharmacological intervention could become a promising new strategy to dampen neuronal hyperexcitability and epileptogenesis.
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20
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Lin P, Lee J, Chen Y, Li F, Ling D. Nanotechnology enabled metal-ion-based disease diagnostics. Sci Bull (Beijing) 2020; 65:1587-1589. [PMID: 36659029 DOI: 10.1016/j.scib.2020.06.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Peihua Lin
- Institute of Pharmaceutics and Hangzhou Institute of Innovative Medicine, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China; Key Laboratory of Biomedical Engineering of Ministry of Education, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou 310058, China
| | - Jiyoung Lee
- Institute of Pharmaceutics and Hangzhou Institute of Innovative Medicine, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Ying Chen
- Institute of Pharmaceutics and Hangzhou Institute of Innovative Medicine, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Fangyuan Li
- Institute of Pharmaceutics and Hangzhou Institute of Innovative Medicine, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China; Key Laboratory of Biomedical Engineering of Ministry of Education, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou 310058, China.
| | - Daishun Ling
- Institute of Pharmaceutics and Hangzhou Institute of Innovative Medicine, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China; Key Laboratory of Biomedical Engineering of Ministry of Education, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou 310058, China.
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21
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Zimmer TS, Broekaart DWM, Gruber VE, van Vliet EA, Mühlebner A, Aronica E. Tuberous Sclerosis Complex as Disease Model for Investigating mTOR-Related Gliopathy During Epileptogenesis. Front Neurol 2020; 11:1028. [PMID: 33041976 PMCID: PMC7527496 DOI: 10.3389/fneur.2020.01028] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 08/06/2020] [Indexed: 12/13/2022] Open
Abstract
Tuberous sclerosis complex (TSC) represents the prototypic monogenic disorder of the mammalian target of rapamycin (mTOR) pathway dysregulation. It provides the rational mechanistic basis of a direct link between gene mutation and brain pathology (structural and functional abnormalities) associated with a complex clinical phenotype including epilepsy, autism, and intellectual disability. So far, research conducted in TSC has been largely neuron-oriented. However, the neuropathological hallmarks of TSC and other malformations of cortical development also include major morphological and functional changes in glial cells involving astrocytes, oligodendrocytes, NG2 glia, and microglia. These cells and their interglial crosstalk may offer new insights into the common neurobiological mechanisms underlying epilepsy and the complex cognitive and behavioral comorbidities that are characteristic of the spectrum of mTOR-associated neurodevelopmental disorders. This review will focus on the role of glial dysfunction, the interaction between glia related to mTOR hyperactivity, and its contribution to epileptogenesis in TSC. Moreover, we will discuss how understanding glial abnormalities in TSC might give valuable insight into the pathophysiological mechanisms that could help to develop novel therapeutic approaches for TSC or other pathologies characterized by glial dysfunction and acquired mTOR hyperactivation.
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Affiliation(s)
- Till S Zimmer
- Department of (Neuro)Pathology, Amsterdam Neuroscience, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands
| | - Diede W M Broekaart
- Department of (Neuro)Pathology, Amsterdam Neuroscience, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands
| | | | - Erwin A van Vliet
- Department of (Neuro)Pathology, Amsterdam Neuroscience, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands.,Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, Netherlands
| | - Angelika Mühlebner
- Department of (Neuro)Pathology, Amsterdam Neuroscience, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands
| | - Eleonora Aronica
- Department of (Neuro)Pathology, Amsterdam Neuroscience, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands.,Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, Netherlands
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22
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Rao VR, G Leguia M, Tcheng TK, Baud MO. Cues for seizure timing. Epilepsia 2020; 62 Suppl 1:S15-S31. [PMID: 32738157 DOI: 10.1111/epi.16611] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 06/20/2020] [Accepted: 06/22/2020] [Indexed: 01/22/2023]
Abstract
The cyclical organization of seizures in epilepsy has been described since antiquity. However, historical explanations for seizure cycles-based on celestial, hormonal, and environmental factors-have only recently become testable with the advent of chronic electroencephalography (cEEG) and modern statistical techniques. Here, factors purported over millennia to influence seizure timing are viewed through a contemporary lens. We discuss the emerging concept that seizures are organized over multiple timescales, each involving differential influences of external and endogenous rhythm generators. Leveraging large cEEG datasets and circular statistics appropriate for cyclical phenomena, we present new evidence for circadian (day-night), multidien (multi-day), and circannual (about-yearly) variation in seizure activity. Modulation of seizure timing by multiscale temporal variables has implications for diagnosis and therapy in clinical epilepsy. Uncovering the mechanistic basis for seizure cycles, particularly the factors that govern multidien periodicity, will be a major focus of future work.
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Affiliation(s)
- Vikram R Rao
- Department of Neurology and Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, California
| | - Marc G Leguia
- Department of Neurology, Sleep-Wake-Epilepsy Center and Center for Experimental Neurology, Inselspital Bern, University Hospital, University of Bern, Bern, Switzerland
| | | | - Maxime O Baud
- Department of Neurology, Sleep-Wake-Epilepsy Center and Center for Experimental Neurology, Inselspital Bern, University Hospital, University of Bern, Bern, Switzerland.,Wyss Center for Bio and Neuroengineering, Geneva, Switzerland
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23
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Octeau JC, Gangwani MR, Allam SL, Tran D, Huang S, Hoang-Trong TM, Golshani P, Rumbell TH, Kozloski JR, Khakh BS. Transient, Consequential Increases in Extracellular Potassium Ions Accompany Channelrhodopsin2 Excitation. Cell Rep 2020; 27:2249-2261.e7. [PMID: 31116972 PMCID: PMC6582980 DOI: 10.1016/j.celrep.2019.04.078] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 03/04/2019] [Accepted: 04/17/2019] [Indexed: 12/13/2022] Open
Abstract
Channelrhodopsin2 (ChR2) optogenetic excitation is widely used to study neurons, astrocytes, and circuits. Using complementary approaches in situ and in vivo, we found that ChR2 stimulation leads to significant transient elevation of extracellular potassium ions by ~5 mM. Such elevations were detected in ChR2-expressing mice, following local in vivo expression of ChR2(H134R) with adeno-associated viruses (AAVs), in different brain areas and when ChR2 was expressed in neurons or astrocytes. In particular, ChR2-mediated excitation of striatal astrocytes was sufficient to increase medium spiny neuron (MSN) excitability and immediate early gene expression. The effects on MSN excitability were recapitulated in silico with a computational MSN model and detected in vivo as increased action potential firing in awake, behaving mice. We show that transient, physiologically consequential increases in extracellular potassium ions accompany ChR2 optogenetic excitation. This coincidental effect may be important to consider during astrocyte studies employing ChR2 to interrogate neural circuits and animal behavior. Using multiple approaches, Octeau et al. discover that optogenetic excitation of ChR2-expressing cells leads to significant transient extracellular potassium ion elevations that increase neuronal excitability and immediate early gene expression in neurons following in vivo stimulation.
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Affiliation(s)
- J Christopher Octeau
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA
| | - Mohitkumar R Gangwani
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA
| | - Sushmita L Allam
- IBM T.J. Watson Research Center, P.O. Box 218, 1101 Kitchawan Road, Yorktown Heights, NY 10598, USA
| | - Duy Tran
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA
| | - Shuhan Huang
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA
| | - Tuan M Hoang-Trong
- IBM T.J. Watson Research Center, P.O. Box 218, 1101 Kitchawan Road, Yorktown Heights, NY 10598, USA
| | - Peyman Golshani
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA; Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA; Intellectual and Developmental Disabilities Research Center, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA; Center for Neurobehavioral Genetics, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA
| | - Timothy H Rumbell
- IBM T.J. Watson Research Center, P.O. Box 218, 1101 Kitchawan Road, Yorktown Heights, NY 10598, USA
| | - James R Kozloski
- IBM T.J. Watson Research Center, P.O. Box 218, 1101 Kitchawan Road, Yorktown Heights, NY 10598, USA
| | - Baljit S Khakh
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA; Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA.
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24
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Temporal phenotyping for transitional disease progress: An application to epilepsy and Alzheimer's disease. J Biomed Inform 2020; 107:103462. [PMID: 32562896 DOI: 10.1016/j.jbi.2020.103462] [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: 11/26/2019] [Revised: 05/27/2020] [Accepted: 05/30/2020] [Indexed: 11/21/2022]
Abstract
Complicated multifactorial diseases deteriorate from one disease to other diseases. For example, existing studies consider Alzheimer's disease (AD) a comorbidity of epilepsy, but also recognize epilepsy to occur more frequently in patients with AD than those without. It is important to understand the progress of disease that deteriorates to severe diseases. To this end, we develop a transitional phenotyping method based on both longitudinal and cross-sectional relationships between diseases and/or medications. For a cross-sectional approach, we utilized a skip-gram model to represent co-occurred disease or medication. For a longitudinal approach, we represented each patient as a transition probability between medical events and used supervised tensor factorization to decompose into groups of medical events that develop together. Then we harmonized both information to derive high-risk transitional patterns. We applied our method to disease progress from epilepsy to AD. An epilepsy-AD cohort of 600,000 patients were extracted from Cerner Health Facts data. Our experimental results suggested a causal relationship between epilepsy and later onset of AD, and also identified five epilepsy subgroups with distinct phenotypic patterns leading to AD. While such findings are preliminary, the proposed method combining representation learning with tensor factorization seems to be an effective approach for risk factor analysis.
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25
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Salami P, Peled N, Nadalin JK, Martinet LE, Kramer MA, Lee JW, Cash SS. Seizure onset location shapes dynamics of initiation. Clin Neurophysiol 2020; 131:1782-1797. [PMID: 32512346 DOI: 10.1016/j.clinph.2020.04.168] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 03/24/2020] [Accepted: 04/13/2020] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Ictal electrographic patterns are widely thought to reflect underlying neural mechanisms of seizures. Here we studied the degree to which seizure patterns are consistent in a given patient, relate to particular brain regions and if two candidate biomarkers (high-frequency oscillations, HFOs; infraslow activity, ISA) and network activity, as assessed with cross-frequency interactions, can discriminate between seizure types. METHODS We analyzed temporal changes in low and high frequency oscillations recorded during seizures, as well as phase-amplitude coupling (PAC) to monitor the interactions between delta/theta and ripple/fast ripple frequency bands at seizure onset. RESULTS Seizures of multiple electrographic patterns were observed in a given patient and brain region. While there was an increase in HFO rate across different electrographic patterns, there are specific relationships between types of HFO activity and onset region. Similarly, changes in PAC dynamics were more closely related to seizure onset region than they were to electrographic patterns while ISA was a poor indicator for seizure onset. CONCLUSIONS Our findings suggest that the onset region sculpts neurodynamics at seizure initiation and that unique features of the cytoarchitecture and/or connectivity of that region play a significant role in determining seizure mechanism. SIGNIFICANCE To learn how seizures are initiated, researchers would do well to consider other aspects of their manifestation, in addition to their electrographic patterns. Examination of onset pattern in conjunction with the interactions between different oscillatory frequencies in the context of different brain regions might be more informative and lead to more reliable clinical inference as well as novel therapeutic approaches.
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Affiliation(s)
- Pariya Salami
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
| | - Noam Peled
- Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Jessica K Nadalin
- Department of Mathematics and Statistics, Boston University, Boston, MA, USA
| | - Louis-Emmanuel Martinet
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Mark A Kramer
- Department of Mathematics and Statistics, Boston University, Boston, MA, USA
| | - Jong W Lee
- Department of Neurology, Brigham and Women's Hospital, Boston, MA, USA
| | - Sydney S Cash
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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26
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Burman RJ, Raimondo JV, Jefferys JG, Sen A, Akerman CJ. The transition to status epilepticus: how the brain meets the demands of perpetual seizure activity. Seizure 2020; 75:137-144. [DOI: 10.1016/j.seizure.2019.09.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 09/23/2019] [Indexed: 02/08/2023] Open
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27
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Rienecker KDA, Poston RG, Saha RN. Merits and Limitations of Studying Neuronal Depolarization-Dependent Processes Using Elevated External Potassium. ASN Neuro 2020; 12:1759091420974807. [PMID: 33256465 PMCID: PMC7711227 DOI: 10.1177/1759091420974807] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 10/07/2020] [Accepted: 10/22/2020] [Indexed: 01/24/2023] Open
Abstract
Elevated extracellular potassium chloride is widely used to achieve membrane depolarization of cultured neurons. This technique has illuminated mechanisms of calcium influx through L-type voltage sensitive calcium channels, activity-regulated signaling, downstream transcriptional events, and many other intracellular responses to depolarization. However, there is enormous variability in these treatments, including durations from seconds to days and concentrations from 3mM to 150 mM KCl. Differential effects of these variable protocols on neuronal activity and transcriptional programs are underexplored. Furthermore, potassium chloride treatments in vitro are criticized for being poor representatives of in vivo phenomena and are questioned for their effects on cell viability. In this review, we discuss the intracellular consequences of elevated extracellular potassium chloride treatment in vitro, the variability of such treatments in the literature, the strengths and limitations of this tool, and relevance of these studies to brain functions and dysfunctions.
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Affiliation(s)
- Kira D. A. Rienecker
- Department of Molecular and Cell Biology,
School of Natural Sciences, University of California, Merced, United
States
| | - Robert G. Poston
- Department of Molecular and Cell Biology,
School of Natural Sciences, University of California, Merced, United
States
| | - Ramendra N. Saha
- Department of Molecular and Cell Biology,
School of Natural Sciences, University of California, Merced, United
States
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28
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Breithausen B, Kautzmann S, Boehlen A, Steinhäuser C, Henneberger C. Limited contribution of astroglial gap junction coupling to buffering of extracellular K + in CA1 stratum radiatum. Glia 2019; 68:918-931. [PMID: 31743499 DOI: 10.1002/glia.23751] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 10/25/2019] [Accepted: 10/29/2019] [Indexed: 12/21/2022]
Abstract
Astrocytes form large networks, in which individual cells are connected via gap junctions. It is thought that this astroglial gap junction coupling contributes to the buffering of extracellular K+ increases. However, it is largely unknown how the control of extracellular K+ by astroglial gap junction coupling depends on the underlying activity patterns and on the magnitude of extracellular K+ increases. We explored this dependency in acute hippocampal slices (CA1, stratum radiatum) by direct K+ -sensitive microelectrode recordings and acute pharmacological inhibition of gap junctions. K+ transients evoked by synaptic and axonal activity were largely unaffected by acute astroglial uncoupling in slices obtained from young and adult rats. Iontophoretic K+ -application enabled us to generate K+ gradients with defined spatial properties and magnitude. By varying the K+ -iontophoresis position and protocol, we found that acute pharmacological uncoupling increases the amplitude of K+ transients once their initial amplitude exceeded ~10 mM. Our experiments demonstrate that the contribution of gap junction coupling to buffering of extracellular K+ gradients is limited to large and localized K+ increases.
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Affiliation(s)
- Björn Breithausen
- Institute of Cellular Neurosciences, University of Bonn Medical School, Bonn, Germany
| | - Steffen Kautzmann
- Institute of Cellular Neurosciences, University of Bonn Medical School, Bonn, Germany
| | - Anne Boehlen
- Institute of Cellular Neurosciences, University of Bonn Medical School, Bonn, Germany
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, University of Bonn Medical School, Bonn, Germany
| | - Christian Henneberger
- Institute of Cellular Neurosciences, University of Bonn Medical School, Bonn, Germany.,Institute of Neurology, University College London, London, UK.,German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
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29
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Klorig DC, Alberto GE, Smith T, Godwin DW. Optogenetically-Induced Population Discharge Threshold as a Sensitive Measure of Network Excitability. eNeuro 2019; 6:ENEURO.0229-18.2019. [PMID: 31619450 PMCID: PMC6838688 DOI: 10.1523/eneuro.0229-18.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 09/06/2019] [Accepted: 09/27/2019] [Indexed: 12/21/2022] Open
Abstract
Network excitability is governed by synaptic efficacy, intrinsic excitability, and the circuitry in which these factors are expressed. The complex interplay between these factors determines how circuits function and, at the extreme, their susceptibility to seizure. We have developed a sensitive, quantitative estimate of network excitability in freely behaving mice using a novel optogenetic intensity-response procedure. Synchronous activation of deep sublayer CA1 pyramidal cells produces abnormal network-wide epileptiform population discharges (PDs) that are nearly indistinguishable from spontaneously-occurring interictal spikes (IISs). By systematically varying light intensity, and therefore the magnitude of the optogenetically-mediated current, we generated intensity-response curves using the probability of PD as the dependent variable. Manipulations known to increase excitability, such as sub-convulsive doses (20 mg/kg) of the chemoconvulsant pentylenetetrazol (PTZ), produced a leftward shift in the curve compared to baseline. The anti-epileptic drug levetiracetam (LEV; 40 mk/kg), in combination with PTZ, produced a rightward shift. Optogenetically-induced PD threshold (oPDT) baselines were stable over time, suggesting the metric is appropriate for within-subject experimental designs with multiple pharmacological manipulations.
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Affiliation(s)
- D C Klorig
- Department of Neurobiology and Anatomy
- Neuroscience Program
| | - G E Alberto
- Department of Neurobiology and Anatomy
- Neuroscience Program
| | - T Smith
- Department of Neurobiology and Anatomy
| | - D W Godwin
- Department of Neurobiology and Anatomy
- Neuroscience Program
- Department of Physiology and Pharmacology, Wake Forest University, Winston-Salem, NC
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30
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ECS Dynamism and Its Influence on Neuronal Excitability and Seizures. Neurochem Res 2019; 44:1020-1036. [DOI: 10.1007/s11064-019-02773-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 03/07/2019] [Accepted: 03/07/2019] [Indexed: 02/08/2023]
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31
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Weiss SA, Staba R, Bragin A, Moxon K, Sperling M, Avoli M, Engel J. "Interneurons and principal cell firing in human limbic areas at focal seizure onset". Neurobiol Dis 2018; 124:183-188. [PMID: 30471414 DOI: 10.1016/j.nbd.2018.11.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 11/11/2018] [Accepted: 11/19/2018] [Indexed: 10/27/2022] Open
Affiliation(s)
- Shennan A Weiss
- Depts. of Neurology and Neuroscience, Thomas Jefferson University, Philadelphia, PA 19107, USA.
| | - Richard Staba
- Dept. of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Anatol Bragin
- Dept. of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Karen Moxon
- Dept. of Biomedical Engineering, UC Davis, Davis, CA 95616, USA
| | - Michael Sperling
- Depts. of Neurology and Neuroscience, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Massimo Avoli
- Montreal Neurological Institute, Depts. of Neurology & Neurosurgery and of Physiology, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Jerome Engel
- Dept. of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA; Dept. of Neurosurgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA; Dept. of Neurobiology, Dept. of Psychiatry and Biobehavioral Sciences, Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
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