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Perveen N, Alqahtani F, Ashraf W, Fawad Rasool M, Muhammad Muneeb Anjum S, Kaukab I, Ahmad T, Alqarni SA, Imran I. Perampanel increases seizure threshold in pentylenetetrazole-kindled mice and improves behavioral dysfunctions by modifying mRNA expression levels of BDNF/TrkB and inflammatory markers. Saudi Pharm J 2024; 32:101930. [PMID: 38226351 PMCID: PMC10788632 DOI: 10.1016/j.jsps.2023.101930] [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: 11/23/2023] [Accepted: 12/18/2023] [Indexed: 01/17/2024] Open
Abstract
Perampanel (PER), a novel 3rd-generation antiseizure drug that modulates altered post-synaptic glutamatergic storming by selectively inhibiting AMPA receptors, is recently approved to treat intractable forms of seizures. However, to date, presumably consequences of long-term PER therapy on the comorbid deleterious psychiatric disturbances and its correlation with neuroinflammatory parameters are not fully investigated in chronic models of epilepsy. Therefore, we investigated the real-time effect of PER on brain electroencephalographic (EEG) activity, behavioral alterations, redox balance, and relative mRNA expression in pentylenetetrazole (PTZ) induced kindling. Male BALB/c mice were pretreated with PER (0.125, 0.25, and 0.5 mg/kg) for 3 weeks and challenged with 11 injections of PTZ at the sub-threshold dose of 40 mg/kg every other day. vEEG from implanted cortical electrodes was monitored to elucidate seizure propagation and behavioral manifestations. Recorded EEG signals exhibited that PER 0.5 mg/kg pretreatment exceptionally impeded the onset of sharp epileptic spike-wave discharges and associated motor symptoms. Additionally, qEEG analysis showed that PER prevented alterations in absolute mean spectral power and reduced RMS amplitude of epileptogenic spikes vs PTZ control. Furthermore, our outcomes illustrated that PER dose-dependently attenuated PTZ-evoked anxiety-like behavior, memory deficits, and depressive-like behavior that was validated by a series of behavioral experiments. Moreover PER, significantly reduced lipid peroxidation, AChE, and increased levels of SOD and total thiol in the mice brain via AMPAR antagonism. Post-PTZ kindling provoked overstimulation of BDNF/TrkB signaling and increased release of pro-inflammatory cytokines that were reversed by PER with suppression of iNOS in brain immune cells. In conclusion, our findings highlight that PER might play an auspicious preventive role in the proepileptic transformation of brain circuits via suppression of BDNF/TrkB signaling and reduced transcriptional levels of neuroinflammatory markers leading to improvised epilepsy-induced neurobehavioral and neurochemical effects.
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Affiliation(s)
- Nadia Perveen
- Department of Pharmacology, Faculty of Pharmacy, Bahauddin Zakariya University, Multan 60800, Pakistan
| | - Faleh Alqahtani
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Waseem Ashraf
- Department of Pharmacology, Faculty of Pharmacy, Bahauddin Zakariya University, Multan 60800, Pakistan
| | - Muhammad Fawad Rasool
- Department of Pharmacy Practice, Faculty of Pharmacy, Bahauddin Zakariya University, Multan 60800, Pakistan
| | - Syed Muhammad Muneeb Anjum
- The Institute of Pharmaceutical Sciences, University of Veterinary & Animal Sciences, Lahore 75270, Pakistan
| | - Iram Kaukab
- District Quality Control Board, Multan, Pakistan
| | - Tanveer Ahmad
- Institut pour l’Avancée des Biosciences, Centre de Recherche UGA/INSERM U1209/CNRS 5309, Université Grenoble Alpes, France
| | - Saleh A. Alqarni
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Imran Imran
- Department of Pharmacology, Faculty of Pharmacy, Bahauddin Zakariya University, Multan 60800, Pakistan
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Brodovskaya A, Sun H, Adotevi N, Wenker IC, Mitchell KE, Clements RT, Kapur J. Neuronal plasticity contributes to postictal death. Prog Neurobiol 2023; 231:102531. [PMID: 37778436 PMCID: PMC10842614 DOI: 10.1016/j.pneurobio.2023.102531] [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: 03/30/2023] [Revised: 08/07/2023] [Accepted: 09/25/2023] [Indexed: 10/03/2023]
Abstract
Repeated generalized tonic-clonic seizures (GTCSs) are the most critical risk factor for sudden unexpected death in epilepsy (SUDEP). GTCSs can cause fatal apnea. We investigated neuronal plasticity mechanisms that precipitate postictal apnea and seizure-induced death. Repeated seizures worsened behavior, precipitated apnea, and enlarged active neuronal circuits, recruiting more neurons in such brainstem nuclei as periaqueductal gray (PAG) and dorsal raphe, indicative of brainstem plasticity. Seizure-activated neurons are more excitable and have enhanced AMPA-mediated excitatory transmission after a seizure. Global deletion of the GluA1 subunit of AMPA receptors abolishes postictal apnea and seizure-induced death. Treatment with a drug that blocks Ca2+-permeable AMPA receptors also renders mice apnea-free with five-fold better survival than untreated mice. Repeated seizures traffic the GluA1 subunit-containing AMPA receptors to synapses, and blocking this mechanism decreases the probability of postictal apnea and seizure-induced death.
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Affiliation(s)
| | - Huayu Sun
- Department of Neurology, University of Virginia, Charlottesville, VA 22908, USA
| | - Nadia Adotevi
- Department of Neurology, University of Virginia, Charlottesville, VA 22908, USA
| | - Ian C Wenker
- Department of Anesthesiology, University of Virginia, Charlottesville, VA 22908, USA
| | - Keri E Mitchell
- Department of Chemistry, University of Virginia, Charlottesville, VA 22908, USA
| | - Rachel T Clements
- Department of Neuroscience, University of Virginia, Charlottesville, VA 22908, USA
| | - Jaideep Kapur
- Department of Neurology, University of Virginia, Charlottesville, VA 22908, USA; UVA Brain Institute, University of Virginia, Charlottesville, VA 22908, USA.
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Skwarzynska D, Sun H, Kasprzak I, Sharma S, Williamson J, Kapur J. Glycolytic lactate production supports status epilepticus in experimental animals. Ann Clin Transl Neurol 2023; 10:1873-1884. [PMID: 37632130 PMCID: PMC10578888 DOI: 10.1002/acn3.51881] [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: 06/20/2023] [Revised: 07/27/2023] [Accepted: 08/09/2023] [Indexed: 08/27/2023] Open
Abstract
OBJECTIVE Status epilepticus (SE) requires rapid intervention to prevent cerebral injury and mortality. The ketogenic diet, which bypasses glycolysis, is a promising remedy for patients with refractory SE. We tested the role of glycolytic lactate production in sustaining SE. METHODS Extracellular lactate and glucose concentration during a seizure and SE in vivo was measured using lactate and glucose biosensors. A lactate dehydrogenase inhibitor, oxamate, blocked pyruvate to lactate conversion during SE. Video-EEG recordings evaluated seizure duration, severity, and immunohistochemistry was used to determine neuronal loss. Genetically encoded calcium indicator GCaMP7 was used to study the effect of oxamate on CA1 pyramidal neurons in vitro. Spontaneous excitatory postsynaptic currents (sEPSCs) were recorded from CA1 neurons to study oxamate's impact on neurotransmission. RESULTS The extracellular glucose concentration dropped rapidly during seizures, and lactate accumulated in the extracellular space. Inhibition of pyruvate to lactate conversion with oxamate terminated SE in mice. There was less neuronal loss in treated compared to control mice. Oxamate perfusion decreased tonic and phasic neuronal activity of GCaMP7-expressing CA1 pyramidal neurons in vitro. Oxamate application reduced the frequency, but not amplitude of sEPSCs recorded from CA1 neurons, suggesting an effect on the presynaptic glutamatergic neurotransmission. INTERPRETATION A single seizure and SE stimulate lactate production. Diminishing pyruvate to lactate conversion with oxamate terminated SE and reduced associated neuronal death. Oxamate reduced neuronal excitability and excitatory neurotransmission at the presynaptic terminal. Glycolytic lactate production sustains SE and is an attractive therapeutic target.
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Affiliation(s)
- Daria Skwarzynska
- Neuroscience Graduate ProgramUniversity of VirginiaCharlottesvilleVirginia22908USA
| | - Huayu Sun
- Department of NeurologyUniversity of VirginiaCharlottesvilleVirginia22908USA
| | - Izabela Kasprzak
- Department of NeurologyUniversity of VirginiaCharlottesvilleVirginia22908USA
| | - Supriya Sharma
- Department of NeurologyUniversity of VirginiaCharlottesvilleVirginia22908USA
| | - John Williamson
- Department of NeurologyUniversity of VirginiaCharlottesvilleVirginia22908USA
| | - Jaideep Kapur
- Department of NeurologyUniversity of VirginiaCharlottesvilleVirginia22908USA
- UVA Brain InstituteUniversity of VirginiaCharlottesvilleVirginia22908USA
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Postnikova TY, Griflyuk AV, Zhigulin AS, Soboleva EB, Barygin OI, Amakhin DV, Zaitsev AV. Febrile Seizures Cause a Rapid Depletion of Calcium-Permeable AMPA Receptors at the Synapses of Principal Neurons in the Entorhinal Cortex and Hippocampus of the Rat. Int J Mol Sci 2023; 24:12621. [PMID: 37628802 PMCID: PMC10454714 DOI: 10.3390/ijms241612621] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Revised: 08/01/2023] [Accepted: 08/09/2023] [Indexed: 08/27/2023] Open
Abstract
Febrile seizures (FSs) are a relatively common early-life condition that can cause CNS developmental disorders, but the specific mechanisms of action of FS are poorly understood. In this work, we used hyperthermia-induced FS in 10-day-old rats. We demonstrated that the efficiency of glutamatergic synaptic transmission decreased rapidly after FS by recording local field potentials. This effect was transient, and after two days there were no differences between control and post-FS groups. During early ontogeny, the proportion of calcium-permeable (CP)-AMPA receptors in the synapses of the principal cortical and hippocampal neurons is high. Therefore, rapid internalization of CP-AMPA receptors may be one of the mechanisms underlying this phenomenon. Using the whole-cell patch-clamp method and the selective CP-AMPA receptor blocker IEM-1460, we tested whether the proportion of CP-AMPA receptors changed. We have demonstrated that FS rapidly reduces synaptic CP-AMPA receptors in both the hippocampus and the entorhinal cortex. This process was accompanied by a sharp decrease in the calcium permeability of the membrane of principal neurons, which we revealed in experiments with kainate-induced cobalt uptake. Our experiments show that FSs cause rapid changes in the function of the glutamatergic system, which may have compensatory effects that prevent excessive excitotoxicity and neuronal death.
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Affiliation(s)
| | | | | | | | | | | | - Aleksey V. Zaitsev
- Sechenov Institute of Evolutionary Physiology and Biochemistry of RAS, 44, Toreza Prospekt, Saint Petersburg 194223, Russia; (T.Y.P.); (A.V.G.); (A.S.Z.); (E.B.S.); (O.I.B.); (D.V.A.)
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Perversi F, Costa C, Labate A, Lattanzi S, Liguori C, Maschio M, Meletti S, Nobili L, Operto FF, Romigi A, Russo E, Di Bonaventura C. The broad-spectrum activity of perampanel: state of the art and future perspective of AMPA antagonism beyond epilepsy. Front Neurol 2023; 14:1182304. [PMID: 37483446 PMCID: PMC10359664 DOI: 10.3389/fneur.2023.1182304] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 06/07/2023] [Indexed: 07/25/2023] Open
Abstract
Glutamate is the brain's main excitatory neurotransmitter. Glutamatergic neurons primarily compose basic neuronal networks, especially in the cortex. An imbalance of excitatory and inhibitory activities may result in epilepsy or other neurological and psychiatric conditions. Among glutamate receptors, AMPA receptors are the predominant mediator of glutamate-induced excitatory neurotransmission and dictate synaptic efficiency and plasticity by their numbers and/or properties. Therefore, they appear to be a major drug target for modulating several brain functions. Perampanel (PER) is a highly selective, noncompetitive AMPA antagonist approved in several countries worldwide for treating different types of seizures in various epileptic conditions. However, recent data show that PER can potentially address many other conditions within epilepsy and beyond. From this perspective, this review aims to examine the new preclinical and clinical studies-especially those produced from 2017 onwards-on AMPA antagonism and PER in conditions such as mesial temporal lobe epilepsy, idiopathic and genetic generalized epilepsy, brain tumor-related epilepsy, status epilepticus, rare epileptic syndromes, stroke, sleep, epilepsy-related migraine, cognitive impairment, autism, dementia, and other neurodegenerative diseases, as well as provide suggestions on future research agenda aimed at probing the possibility of treating these conditions with PER and/or other AMPA receptor antagonists.
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Affiliation(s)
| | - Cinzia Costa
- Section of Neurology, Department of Medicine and Surgery, University of Perugia, Perugia, Italy
- Neurological Clinic, S. Maria Della Misericordia Hospital, Perugia, Italy
| | - Angelo Labate
- Neurophysiopatology and Movement Disorders Clinic, University of Messina, Messina, Italy
| | - Simona Lattanzi
- Neurological Clinic, Department of Experimental and Clinical Medicine, Marche Polytechnic University, Ancona, Italy
| | - Claudio Liguori
- Department of Systems Medicine, University of Rome ‘Tor Vergata”, Rome, Italy
- Epilepsy Center, Neurology Unit, University Hospital “Tor Vergata”, Rome, Italy
| | - Marta Maschio
- Center for Tumor-Related Epilepsy, UOSD Neuro-Oncology, IRCCS Regina Elena National Cancer Institute, Rome, Italy
| | - Stefano Meletti
- Neurology Department, University Hospital of Modena, Modena, Italy
- Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio-Emilia, Modena, Italy
| | - Lino Nobili
- Child Neuropsychiatry Unit, IRCCS Istituto G. Gaslini, Genova, Italy
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Child and Maternal Health (DINOGMI), University of Genova, Genova, Italy
| | - Francesca Felicia Operto
- Child and Adolescent Neuropsychiatry Unit, Department of Medicine, Surgery and Dentistry, University of Salerno, Salerno, Italy
- Department of Science of Health, School of Medicine, University Magna Graecia of Catanzaro, Catanzaro, Italy
| | - Andrea Romigi
- Sleep Medicine Center, Neurological Mediterranean Institute IRCCS Neuromed, Pozzilli, Italy
- Psychology Faculty, International Telematic University Uninettuno, Rome, Italy
| | - Emilio Russo
- Department of Science of Health, School of Medicine, University Magna Graecia of Catanzaro, Catanzaro, Italy
| | - Carlo Di Bonaventura
- Epilepsy Unit, Department of Human Neurosciences, Sapienza University of Rome, Rome, Italy
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Naylor DE. In the fast lane: Receptor trafficking during status epilepticus. Epilepsia Open 2023; 8 Suppl 1:S35-S65. [PMID: 36861477 PMCID: PMC10173858 DOI: 10.1002/epi4.12718] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 02/23/2023] [Indexed: 03/03/2023] Open
Abstract
Status epilepticus (SE) remains a significant cause of morbidity and mortality and often is refractory to standard first-line treatments. A rapid loss of synaptic inhibition and development of pharmacoresistance to benzodiazepines (BZDs) occurs early during SE, while NMDA and AMPA receptor antagonists remain effective treatments after BZDs have failed. Multimodal and subunit-selective receptor trafficking within minutes to an hour of SE involves GABA-A, NMDA, and AMPA receptors and contributes to shifts in the number and subunit composition of surface receptors with differential impacts on the physiology, pharmacology, and strength of GABAergic and glutamatergic currents at synaptic and extrasynaptic sites. During the first hour of SE, synaptic GABA-A receptors containing γ2 subunits move to the cell interior while extrasynaptic GABA-A receptors with δ subunits are preserved. Conversely, NMDA receptors containing N2B subunits are increased at synaptic and extrasynaptic sites, and homomeric GluA1 ("GluA2-lacking") calcium permeant AMPA receptor surface expression also is increased. Molecular mechanisms, largely driven by NMDA receptor or calcium permeant AMPA receptor activation early during circuit hyperactivity, regulate subunit-specific interactions with proteins involved with synaptic scaffolding, adaptin-AP2/clathrin-dependent endocytosis, endoplasmic reticulum (ER) retention, and endosomal recycling. Reviewed here is how SE-induced shifts in receptor subunit composition and surface representation increase the excitatory to inhibitory imbalance that sustains seizures and fuels excitotoxicity contributing to chronic sequela such as "spontaneous recurrent seizures" (SRS). A role for early multimodal therapy is suggested both for treatment of SE and for prevention of long-term comorbidities.
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Affiliation(s)
- David E Naylor
- VA Greater Los Angeles Healthcare System, Department of Neurology, David Geffen School of Medicine at UCLA, and The Lundquist Institute at Harbor-UCLA Medical Center, Los Angeles, California, USA
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Fisch U, Jünger AL, Hert L, Rüegg S, Sutter R. Therapeutically induced EEG burst-suppression pattern to treat refractory status epilepticus—what is the evidence? ZEITSCHRIFT FÜR EPILEPTOLOGIE 2022. [DOI: 10.1007/s10309-022-00539-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractCurrent guidelines advocate to treat refractory status epilepticus (RSE) with continuously administered anesthetics to induce an artificial coma if first- and second-line antiseizure drugs have failed to stop seizure activity. A common surrogate for monitoring the depth of the artificial coma is the appearance of a burst-suppression pattern (BS) in the EEG. This review summarizes the current knowledge on the origin and neurophysiology of the BS phenomenon as well as the evidence from the literature for the presumed benefit of BS as therapy in adult patients with RSE.
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Kapur J, Long L, Dixon-Salazar T. Consequences: Bench to home. Epilepsia 2022; 63 Suppl 1:S14-S24. [PMID: 35999173 DOI: 10.1111/epi.17342] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 06/08/2022] [Accepted: 06/08/2022] [Indexed: 01/02/2023]
Abstract
Seizure clusters (also referred to as acute repetitive seizures) consist of several seizures interspersed with brief interictal periods. Seizure clusters can break down γ-aminobutyric acidergic (GABAergic) inhibition of dentate granule cells, leading to hyperactivation. Functional changes to GABAA receptors, which play a vital neuroinhibitory role, can include altered GABAA receptor subunit trafficking and cellular localization, intracellular chloride accumulation, and dysregulation of proteins critical to chloride homeostasis. A reduction in neuroinhibition and potentiation of excitatory neurotransmission in CA1 pyramidal neurons represent pathological mechanisms that underlie seizure clusters. Benzodiazepines are well-established treatments for seizure clusters; however, there remain barriers to appropriate care. At the clinical level, there is variability in seizure cluster definitions, such as the number and/or type of seizures associated with a cluster as well as the interictal duration between seizures. This can lead to delays in diagnosis and timely treatment. There are gaps in understanding between clinicians, their patients, and caregivers regarding acute treatment for seizure clusters, such as the use of rescue medications and emergency services. This lack of consensus to define seizure clusters in addition to a lack of education for appropriate treatment can affect quality of life for patients and place a greater burden on patient families and caregivers. For patients with seizure clusters, the sense of unpredictability can lead to continuous traumatic stress, during which patients and families live with a heightened level of anxiety. Clinicians can affect patient quality of life and clinical outcomes through improved seizure cluster education and treatment, such as the development and implementation of a personalized seizure action plan as well as prescriptions for suitable rescue medications indicated for seizure clusters and instructions for their proper use. In all, the combination of targeted therapy along with patient education and support can improve quality of life.
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Affiliation(s)
- Jaideep Kapur
- Department of Neurology, University of Virginia, Charlottesville, Virginia, USA
| | - Lucretia Long
- Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA
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Naik AA, Brodovskaya A, Subedi S, Akram A, Kapur J. Extrahippocampal seizure and memory circuits overlap. eNeuro 2022; 9:ENEURO.0179-22.2022. [PMID: 35853724 PMCID: PMC9319425 DOI: 10.1523/eneuro.0179-22.2022] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 06/08/2022] [Accepted: 06/24/2022] [Indexed: 11/21/2022] Open
Abstract
Seizures cause retrograde amnesia. We have previously demonstrated that seizures erode recently formed memories through shared ensembles and mechanisms in the CA1 region of the hippocampus. Here, we tested whether seizure circuits overlap spatial memory circuits outside of the CA. Spatial memory is consolidated by the hippocampal-cortical coupling that are connected via multiple pathways. We tested whether a seizure invades structures involved in memory consolidation by using the activity reporter TRAP2 mice. T-maze alternation learning activated neurons in the dentate gyrus, mediodorsal thalamus, retrosplenial cortex, and medial prefrontal cortex. This spatial memory relies on the plasticity of the AMPA receptor GluA1 subunit. GluA1 knockout/TRAP2 mice did not learn to alternate, and structures interposed between the hippocampus and the cortex were not active. A seizure prevented the recall of alternation memory and activated memory-labeled structures. There was a widespread overlap between learning-activated ensembles and seizure-activated neurons, which likely contributes to retrograde amnesia.Significance StatementWe propose that seizures cause retrograde amnesia by engaging the circuits that participate in memory consolidation.
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Affiliation(s)
- Aijaz Ahmad Naik
- Department of Neurology, University of Virginia, Charlottesville, VA 22903
| | | | - Smriti Subedi
- College of Arts and Sciences, University of Virginia, Charlottesville, VA 22903
| | - Amman Akram
- College of Arts and Sciences, University of Virginia, Charlottesville, VA 22903
| | - Jaideep Kapur
- Department of Neurology, University of Virginia, Charlottesville, VA 22903
- UVA Brain Institute, University of Virginia, Charlottesville, VA 22903
- Department of Neuroscience, University of Virginia, Charlottesville, VA 22903
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10
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Search for Selective Glua1 Ampa Receptor Antagonists in a Series of Dicationic Compounds. Pharm Chem J 2022. [DOI: 10.1007/s11094-022-02635-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Migdady I, Rosenthal ES, Cock HR. Management of status epilepticus: a narrative review. Anaesthesia 2022; 77 Suppl 1:78-91. [PMID: 35001380 DOI: 10.1111/anae.15606] [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] [Accepted: 10/01/2021] [Indexed: 11/26/2022]
Abstract
Status epilepticus causes prolonged or repetitive seizures that, if left untreated, can lead to neuronal injury, severe disability, coma and death in paediatric and adult populations. While convulsive status epilepticus can be diagnosed using clinical features alone, non-convulsive status epilepticus requires confirmation by electroencephalogram. Early seizure control remains key in preventing the complications of status epilepticus. This is especially true for convulsive status epilepticus, which has stronger evidence supporting the benefit of treatment on outcomes. When status epilepticus becomes refractory, often due to gamma-aminobutyric acid and N-methyl-D-aspartate receptor modulation, anaesthetic drugs are needed to suppress seizure activity, of which there is limited evidence regarding the selection, dose or duration of their use. Seizure monitoring with electroencephalogram is often needed when patients do not return to baseline or during anaesthetic wean; however, it is resource-intensive, costly, only available in highly specialised centres and has not been shown to improve functional outcomes. Thus, the treatment goals and aggressiveness of therapy remain under debate, especially for non-convulsive status epilepticus, where prolonged therapeutic coma can lead to severe complications. This review presents an evidence-based, clinically-oriented and comprehensive review of status epilepticus and its definitions, aetiologies, treatments, outcomes and prognosis at different stages of the patient's journey.
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Affiliation(s)
- I Migdady
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - E S Rosenthal
- Department of Neurology, Divisions of Clinical Neurophysiology and Neurocritical Care Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - H R Cock
- Clinical Neurosciences Academic Group, Institute of Molecular and Clinical Sciences, St. George's University of London, London, UK
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12
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Amakhin DV, Soboleva EB, Chizhov AV, Zaitsev AV. Insertion of Calcium-Permeable AMPA Receptors during Epileptiform Activity In Vitro Modulates Excitability of Principal Neurons in the Rat Entorhinal Cortex. Int J Mol Sci 2021; 22:12174. [PMID: 34830051 PMCID: PMC8621524 DOI: 10.3390/ijms222212174] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 11/05/2021] [Accepted: 11/07/2021] [Indexed: 12/19/2022] Open
Abstract
Epileptic activity leads to rapid insertion of calcium-permeable α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (CP-AMPARs) into the synapses of cortical and hippocampal glutamatergic neurons, which generally do not express them. The physiological significance of this process is not yet fully understood; however, it is usually assumed to be a pathological process that augments epileptic activity. Using whole-cell patch-clamp recordings in rat entorhinal cortex slices, we demonstrate that the timing of epileptiform discharges, induced by 4-aminopyridine and gabazine, is determined by the shunting effect of Ca2+-dependent slow conductance, mediated predominantly by K+-channels. The blockade of CP-AMPARs by IEM-1460 eliminates this extra conductance and consequently increases the rate of discharge generation. The blockade of NMDARs reduced the additional conductance to a lesser extent than the blockade of CP-AMPARs, indicating that CP-AMPARs are a more significant source of intracellular Ca2+. The study's main findings were implemented in a mathematical model, which reproduces the shunting effect of activity-dependent conductance on the generation of discharges. The obtained results suggest that the expression of CP-AMPARs in principal neurons reduces the discharge generation rate and may be considered as a protective mechanism.
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Affiliation(s)
- Dmitry V. Amakhin
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Toreza Prospekt 44, 194223 Saint Petersburg, Russia; (D.V.A.); (E.B.S.); (A.V.C.)
| | - Elena B. Soboleva
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Toreza Prospekt 44, 194223 Saint Petersburg, Russia; (D.V.A.); (E.B.S.); (A.V.C.)
| | - Anton V. Chizhov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Toreza Prospekt 44, 194223 Saint Petersburg, Russia; (D.V.A.); (E.B.S.); (A.V.C.)
- Ioffe Institute, Russian Academy of Sciences, Polytekhnicheskaya 26, 194021 Saint Petersburg, Russia
| | - Aleksey V. Zaitsev
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Toreza Prospekt 44, 194223 Saint Petersburg, Russia; (D.V.A.); (E.B.S.); (A.V.C.)
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Cruz Del Angel Y, Orfila JE, Herson PS, Brooks-Kayal A, González MI. Down-regulation of AMPA receptors and long-term potentiation during early epileptogenesis. Epilepsy Behav 2021; 124:108320. [PMID: 34592633 DOI: 10.1016/j.yebeh.2021.108320] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 08/24/2021] [Accepted: 08/31/2021] [Indexed: 10/20/2022]
Abstract
Epilepsy is a brain disorder characterized by the occurrence of recurrent spontaneous seizures. Behavioral disorders and altered cognition are frequent comorbidities affecting the quality of life of people with epilepsy. These impairments are undoubtedly multifactorial and the specific mechanisms underlying these comorbidities are largely unknown. Long-lasting alterations in synaptic strength due to changes in expression, phosphorylation, or function of α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors (AMPARs) have been associated with alterations in neuronal synaptic plasticity. In particular, alterations in hippocampal long-term potentiation (LTP), a well-accepted model of learning and memory, have been associated with altered cognition in epilepsy. Here, we analyzed the effects of pilocarpine-induced status epilepticus (SE) on AMPARs to determine if alterations in AMPAR signaling might be one of the mechanisms contributing to altered cognition during epilepsy. We found alterations in the phosphorylation and plasma membrane expression of AMPARs. In addition, we detected altered expression of GRIP, a key scaffolding protein involved in the proper distribution of AMPARs at the neuronal cell surface. Interestingly, a functional analysis revealed that these molecular changes are linked to impaired LTP. Together, these observations suggest that seizure-induced alterations in the molecular machinery regulating AMPARs likely impact the neuron's ability to support synaptic plasticity that is required for learning and memory.
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Affiliation(s)
- Yasmin Cruz Del Angel
- Department of Pediatrics, Division of Neurology and Translational Epilepsy Research Program, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - James E Orfila
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Paco S Herson
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Neuroscience Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Amy Brooks-Kayal
- Department of Pediatrics, Division of Neurology and Translational Epilepsy Research Program, University of Colorado School of Medicine, Aurora, CO 80045, USA; Neuroscience Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; Children's Hospital Colorado, Aurora, CO 80045, USA
| | - Marco I González
- Department of Pediatrics, Division of Neurology and Translational Epilepsy Research Program, University of Colorado School of Medicine, Aurora, CO 80045, USA; Neuroscience Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
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14
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Shiono S, Sun H, Batabyal T, Labuz A, Williamson J, Kapur J, Joshi S. Limbic progesterone receptor activity enhances neuronal excitability and seizures. Epilepsia 2021; 62:1946-1959. [PMID: 34164810 DOI: 10.1111/epi.16970] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 06/03/2021] [Accepted: 06/04/2021] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Emerging evidence raises the possibility that progesterone receptor (PR) signaling may contribute to the reproductive hormone fluctuation-linked seizure precipitation, called catamenial epilepsy. Therefore, we studied PR isoform expression in limbic regions involved in temporal lobe epilepsy and the effect of PR activation on neuronal activity and seizures. METHODS We evaluated PR expression in the limbic regions, entorhinal cortex (EC), hippocampus, and amygdala in female rats using quantitative real-time polymerase chain reaction (qRT-PCR). A selective agonist, Nestorone (16-methylene-17 alpha-acetoxy-19-nor-pregn-4-ene-3,20-dione) activated PRs, and the effect on excitability and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-mediated synaptic transmission of EC neurons was studied using electrophysiology. Finally, we assessed PR regulation of epileptic seizures and status epilepticus (SE) induced by lithium-pilocarpine in female rats with the global deletion of PRs (PR knockout; PRKO) using video electroencephalography (-EEG). RESULTS Limbic regions EC, hippocampus, and amygdala robustly expressed PR messenger RNA (mRNA). Nestorone (16-methylene-17 alpha-acetoxy-19-nor-pregn-4-ene-3,20-dione) treatment reduced the action potential threshold of layer II/III EC neurons and increased the frequency of AMPA receptor-mediated synaptic currents of ovariectomized and estrogen-primed female rats. Female rats lacking PRs (PRKO) experienced a shorter duration, less intense, and less fatal SE than wild-type (WT) animals. Furthermore, Nestorone treatment caused seizure exacerbation in the WT epileptic animals, but not in the PRKO epileptic animals. SIGNIFICANCE Activation of PRs expressed in the EC and hippocampus increased neuronal excitability and worsened seizures. These receptors may play a role in catamenial epilepsy.
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Affiliation(s)
- Shinnosuke Shiono
- Department of Neurology, University of Virginia-HSC, Charlottesville, VA, USA
| | - Huayu Sun
- Department of Neurology, University of Virginia-HSC, Charlottesville, VA, USA
| | - Tamal Batabyal
- Department of Neurology, University of Virginia-HSC, Charlottesville, VA, USA
| | - Aleksandra Labuz
- Department of Neurology, University of Virginia-HSC, Charlottesville, VA, USA
| | - John Williamson
- Department of Neurology, University of Virginia-HSC, Charlottesville, VA, USA
| | - Jaideep Kapur
- Department of Neurology, University of Virginia-HSC, Charlottesville, VA, USA.,Department of Neuroscience, University of Virginia-HSC, Charlottesville, VA, USA.,UVA Brain Institute, University of Virginia-HSC, Charlottesville, VA, USA
| | - Suchitra Joshi
- Department of Neurology, University of Virginia-HSC, Charlottesville, VA, USA
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15
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Cull‐Candy SG, Farrant M. Ca 2+ -permeable AMPA receptors and their auxiliary subunits in synaptic plasticity and disease. J Physiol 2021; 599:2655-2671. [PMID: 33533533 PMCID: PMC8436767 DOI: 10.1113/jp279029] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 01/28/2021] [Indexed: 12/14/2022] Open
Abstract
AMPA receptors are tetrameric glutamate-gated ion channels that mediate a majority of fast excitatory neurotransmission in the brain. They exist as calcium-impermeable (CI-) and calcium-permeable (CP-) subtypes, the latter of which lacks the GluA2 subunit. CP-AMPARs display an array of distinctive biophysical and pharmacological properties that allow them to be functionally identified. This has revealed that they play crucial roles in diverse forms of central synaptic plasticity. Here we summarise the functional hallmarks of CP-AMPARs and describe how these are modified by the presence of auxiliary subunits that have emerged as pivotal regulators of AMPARs. A lasting change in the prevalence of GluA2-containing AMPARs, and hence in the fraction of CP-AMPARs, is a feature in many maladaptive forms of synaptic plasticity and neurological disorders. These include modifications of glutamatergic transmission induced by inflammatory pain, fear conditioning, cocaine exposure, and anoxia-induced damage in neurons and glia. Furthermore, defective RNA editing of GluA2 can cause altered expression of CP-AMPARs and is implicated in motor neuron damage (amyotrophic lateral sclerosis) and the proliferation of cells in malignant gliomas. A number of the players involved in CP-AMPAR regulation have been identified, providing useful insight into interventions that may prevent the aberrant CP-AMPAR expression. Furthermore, recent molecular and pharmacological developments, particularly the discovery of TARP subtype-selective drugs, offer the exciting potential to modify some of the harmful effects of increased CP-AMPAR prevalence in a brain region-specific manner.
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Affiliation(s)
- Stuart G. Cull‐Candy
- Department of Neuroscience, Physiology and PharmacologyUniversity College LondonGower StreetLondonWC1E 6BTUK
| | - Mark Farrant
- Department of Neuroscience, Physiology and PharmacologyUniversity College LondonGower StreetLondonWC1E 6BTUK
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16
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Aroniadou-Anderjaska V, Apland JP, Figueiredo TH, De Araujo Furtado M, Braga MF. Acetylcholinesterase inhibitors (nerve agents) as weapons of mass destruction: History, mechanisms of action, and medical countermeasures. Neuropharmacology 2020; 181:108298. [DOI: 10.1016/j.neuropharm.2020.108298] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 08/21/2020] [Accepted: 09/02/2020] [Indexed: 02/07/2023]
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17
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Weisenberg JLZ, Fitzgerald RT, Constantino JN, Winawer MR, Thio LL. Familial aggregation of status epilepticus in generalized and focal epilepsies. Neurology 2020; 95:e2140-e2149. [PMID: 32917807 DOI: 10.1212/wnl.0000000000010708] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Accepted: 05/08/2020] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To determine whether familial aggregation of status epilepticus (SE) occurs in a large cohort of familial common epilepsies. METHODS We used the Epilepsy Phenome/Genome Project dataset, which consisted of 2,197 participants in 1,043 family units with ≥2 members having a common generalized or nonacquired focal epilepsy (NAFE). We identified participants with a history of traditionally defined SE (TSE) (seizures ≥30 minutes) and operationally defined SE (OSE) (seizures ≥10 minutes) by chart review. We assessed familial aggregation of TSE and OSE using χ2 analysis and generalized estimating equations (GEE). RESULTS One hundred fifty-five (7%) participants in 1,043 families had ≥1 episodes of TSE. Two hundred fifty (11%) had ≥1 episodes of OSE. In a χ2 analysis, the number of family units with ≥2 members having TSE (odds ratio [OR] 4.79, 95% confidence interval [CI] 2.56-8.97) or OSE (OR 4.23, 95% CI 2.67-6.70) was greater than expected by chance. In GEE models adjusted for sex, broad epilepsy class (GE or NAFE), age at onset, and duration of epilepsy, TSE in a proband predicted TSE in a first-degree relative (OR 2.79, 95% CI 1.24-6.22), and OSE in a proband predicted OSE in a first-degree relative (OR 2.91, 95% CI 1.65-5.15). The results remained significant in models addressing epilepsy severity by incorporating the number of antiseizure medications used or epilepsy surgery. CONCLUSIONS TSE and OSE showed robust familial aggregation in a cohort of familial epilepsy independently of epilepsy severity or class, suggesting that genetic factors contribute to SE independently of the genetic cause of these epilepsies. CLINICALTRIALSGOV IDENTIFIER NCT00552045.
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Affiliation(s)
- Judith L Z Weisenberg
- From the Division of Pediatric and Developmental Neurology, Department of Neurology (J.L.Z.W., L.L.T.) and Department of Psychiatry (R.T.F., J.N.C.), Washington University, St. Louis, MO; and Department of Neurology (M.R.W.), College of Physicians and Surgeons, Columbia University, New York, NY.
| | - Robert T Fitzgerald
- From the Division of Pediatric and Developmental Neurology, Department of Neurology (J.L.Z.W., L.L.T.) and Department of Psychiatry (R.T.F., J.N.C.), Washington University, St. Louis, MO; and Department of Neurology (M.R.W.), College of Physicians and Surgeons, Columbia University, New York, NY
| | - John N Constantino
- From the Division of Pediatric and Developmental Neurology, Department of Neurology (J.L.Z.W., L.L.T.) and Department of Psychiatry (R.T.F., J.N.C.), Washington University, St. Louis, MO; and Department of Neurology (M.R.W.), College of Physicians and Surgeons, Columbia University, New York, NY
| | - Melodie R Winawer
- From the Division of Pediatric and Developmental Neurology, Department of Neurology (J.L.Z.W., L.L.T.) and Department of Psychiatry (R.T.F., J.N.C.), Washington University, St. Louis, MO; and Department of Neurology (M.R.W.), College of Physicians and Surgeons, Columbia University, New York, NY
| | - Liu Lin Thio
- From the Division of Pediatric and Developmental Neurology, Department of Neurology (J.L.Z.W., L.L.T.) and Department of Psychiatry (R.T.F., J.N.C.), Washington University, St. Louis, MO; and Department of Neurology (M.R.W.), College of Physicians and Surgeons, Columbia University, New York, NY
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18
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Gross C. Sustainable Brain Activity and no End in Sight—What’s in It for Status Epilepticus? Epilepsy Curr 2020; 20:113-115. [PMID: 32313508 PMCID: PMC7160873 DOI: 10.1177/1535759720901509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
α-Amino-3-Hydroxy-5-Methyl-4-Isoxazolepropionic Acid Receptor Plasticity Sustains Severe, Fatal Status Epilepticus. Adotevi N, Lewczuk E, Sun H, Joshi S, Dabrowska N, Shan S, Williamson J, Kapur J. Ann Neurol. 2020;87(1):84-96. doi: 10.1002/ana.25635. Epub 2019 Nov 20. OBJECTIVE: Generalized convulsive status epilepticus is associated with high mortality. We tested whether α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor plasticity plays a role in sustaining seizures, seizure generalization, and mortality observed during focal onset status epilepticus. We also determined whether modified AMPA receptors generated during status epilepticus could be targeted with a drug. METHODS: Electrically induced status epilepticus was characterized by electroencephalogram and behavior in GluA1 knockout mice and in transgenic mice with selective knockdown of the GluA1 subunit in hippocampal principal neurons. Excitatory and inhibitory synaptic transmission in CA1 neurons was studied using patch clamp electrophysiology. The dose-response of N, N, H,-trimethyl-5-([tricyclo(3.3.1.13,7)dec-1-ylmethyl]amino)-1-pentanaminiumbromide hydrobromide (IEM-1460), a calcium-permeable AMPA receptor antagonist, was determined. RESULTS: Global removal of the GluA1 subunit did not affect seizure susceptibility; however, it reduced susceptibility to status epilepticus. GluA1 subunit knockout also reduced mortality, severity, and duration of status epilepticus. Absence of the GluA1 subunit prevented enhancement of glutamatergic synaptic transmission associated with status epilepticus; however, γ-aminobutyric acidergic synaptic inhibition was compromised. Selective removal of the GluA1 subunit from hippocampal principal neurons also reduced mortality, severity, and duration of status epilepticus. IEM-1460 rapidly terminated status epilepticus in a dose-dependent manner. INTERPRETATION: α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor plasticity mediated by the GluA1 subunit plays a critical role in sustaining and amplifying seizure activity and contributes to mortality. Calcium-permeable AMPA receptors modified during status epilepticus can be inhibited to terminate status epilepticus. Excitatory GABAergic Signalling Is Associated With Benzodiazepine Resistance in Status Epilepticus Burman RJ, Selfe JS, Lee JH, van den Berg M, Calin A, Codadu NK, Wright R, Newey SE, Parrish RR, Katz AA, Wilmshurst JM, Akerman CJ, Trevelyan AJ, Raimondo JV. Brain. 2019;142(11):3482-3501. doi:10.1093/brain/awz283. Status epilepticus is defined as a state of unrelenting seizure activity. Generalized convulsive status epilepticus is associated with a rapidly rising mortality rate, and thus constitutes a medical emergency. Benzodiazepines, which act as positive modulators of chloride (Cl−) permeable GABAA receptors, are indicated as first-line treatment, but this is ineffective in many cases. We found that 48% of children presenting with status epilepticus were unresponsive to benzodiazepine treatment, and critically, that the duration of status epilepticus at the time of treatment is an important predictor of nonresponsiveness. We therefore investigated the cellular mechanisms that underlie acquired benzodiazepine resistance, using rodent organotypic and acute brain slices. Removing Mg2+ ions leads to an evolving pattern of epileptiform activity, and eventually to a persistent state of repetitive discharges that strongly resembles clinical electroencephalogram recordings of status epilepticus. We found that diazepam loses its antiseizure efficacy and conversely exacerbates epileptiform activity during this stage of status epilepticus-like activity. Interestingly, a low concentration of the barbiturate phenobarbital had a similar exacerbating effect on status epilepticus-like activity, while a high concentration of phenobarbital was effective at reducing or preventing epileptiform discharges. We then show that the persistent status epilepticus-like activity is associated with a reduction in GABAA receptor conductance and Cl− extrusion capability. We explored the effect on intraneuronal Cl− using both gramicidin, perforated-patch clamp recordings and Cl− imaging. This showed that during status epilepticus-like activity, reduced Cl− extrusion capacity was further exacerbated by activity-dependent Cl− loading, resulting in a persistently high intraneuronal Cl−. Consistent with these results, we found that optogenetic stimulation of GABAergic interneurons in the status epilepticus-like state, actually enhanced epileptiform activity in a GABAAR dependent manner. Together our findings describe a novel potential mechanism underlying benzodiazepine-resistant status epilepticus, with relevance to how this life-threatening condition should be managed in the clinic.
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19
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Konen LM, Wright AL, Royle GA, Morris GP, Lau BK, Seow PW, Zinn R, Milham LT, Vaughan CW, Vissel B. A new mouse line with reduced GluA2 Q/R site RNA editing exhibits loss of dendritic spines, hippocampal CA1-neuron loss, learning and memory impairments and NMDA receptor-independent seizure vulnerability. Mol Brain 2020; 13:27. [PMID: 32102661 PMCID: PMC7045468 DOI: 10.1186/s13041-020-0545-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 01/05/2020] [Indexed: 11/18/2022] Open
Abstract
Calcium (Ca2+)-permeable AMPA receptors may, in certain circumstances, contribute to normal synaptic plasticity or to neurodegeneration. AMPA receptors are Ca2+-permeable if they lack the GluA2 subunit or if GluA2 is unedited at a single nucleic acid, known as the Q/R site. In this study, we examined mice engineered with a point mutation in the intronic editing complementary sequence (ECS) of the GluA2 gene, Gria2. Mice heterozygous for the ECS mutation (named GluA2+/ECS(G)) had a ~ 20% reduction in GluA2 RNA editing at the Q/R site. We conducted an initial phenotypic analysis of these mice, finding altered current-voltage relations (confirming expression of Ca2+-permeable AMPA receptors at the synapse). Anatomically, we observed a loss of hippocampal CA1 neurons, altered dendritic morphology and reductions in CA1 pyramidal cell spine density. Behaviourally, GluA2+/ECS(G) mice exhibited reduced motor coordination, and learning and memory impairments. Notably, the mice also exhibited both NMDA receptor-independent long-term potentiation (LTP) and vulnerability to NMDA receptor-independent seizures. These NMDA receptor-independent seizures were rescued by the Ca2+-permeable AMPA receptor antagonist IEM-1460. In summary, unedited GluA2(Q) may have the potential to drive NMDA receptor-independent processes in brain function and disease. Our study provides an initial characterisation of a new mouse model for studying the role of unedited GluA2(Q) in synaptic and dendritic spine plasticity in disorders where unedited GluA2(Q), synapse loss, neurodegeneration, behavioural impairments and/or seizures are observed, such as ischemia, seizures and epilepsy, Huntington’s disease, amyotrophic lateral sclerosis, astrocytoma, cocaine seeking behaviour and Alzheimer’s disease.
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Affiliation(s)
- Lyndsey M Konen
- Centre for Neuroscience and Regenerative Medicine (CNRM), Faculty of Science, University of Technology Sydney, PO Box 123 Broadway, Sydney, NSW, 2007, Australia.,St Vincent's Centre for Applied Medical Research, Sydney, 2011, Australia
| | - Amanda L Wright
- Department of Biomedical Sciences, Faculty of Medicine & Health Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia
| | - Gordon A Royle
- Middlemore Hospital, Counties Manukau DHB, Otahuhu, Auckland, 1062, New Zealand.,The University of Auckland, Faculty of Medical and Health Sciences, School of Medicine, Grafton, Auckland, 1023, New Zealand
| | - Gary P Morris
- Centre for Neuroscience and Regenerative Medicine (CNRM), Faculty of Science, University of Technology Sydney, PO Box 123 Broadway, Sydney, NSW, 2007, Australia.,St Vincent's Centre for Applied Medical Research, Sydney, 2011, Australia
| | - Benjamin K Lau
- Kolling Institute of Medical Research, Royal North Shore Hospital, The University of Sydney, Sydney, 2065, Australia
| | - Patrick W Seow
- Kolling Institute of Medical Research, Royal North Shore Hospital, The University of Sydney, Sydney, 2065, Australia
| | - Raphael Zinn
- Centre for Neuroscience and Regenerative Medicine (CNRM), Faculty of Science, University of Technology Sydney, PO Box 123 Broadway, Sydney, NSW, 2007, Australia.,St Vincent's Centre for Applied Medical Research, Sydney, 2011, Australia
| | - Luke T Milham
- Centre for Neuroscience and Regenerative Medicine (CNRM), Faculty of Science, University of Technology Sydney, PO Box 123 Broadway, Sydney, NSW, 2007, Australia.,St Vincent's Centre for Applied Medical Research, Sydney, 2011, Australia
| | - Christopher W Vaughan
- Kolling Institute of Medical Research, Royal North Shore Hospital, The University of Sydney, Sydney, 2065, Australia
| | - Bryce Vissel
- Centre for Neuroscience and Regenerative Medicine (CNRM), Faculty of Science, University of Technology Sydney, PO Box 123 Broadway, Sydney, NSW, 2007, Australia. .,St Vincent's Centre for Applied Medical Research, Sydney, 2011, Australia.
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