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Enger R, Heuser K. Astrocytes as critical players of the fine balance between inhibition and excitation in the brain: spreading depolarization as a mechanism to curb epileptic activity. FRONTIERS IN NETWORK PHYSIOLOGY 2024; 4:1360297. [PMID: 38405021 PMCID: PMC10884165 DOI: 10.3389/fnetp.2024.1360297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 01/25/2024] [Indexed: 02/27/2024]
Abstract
Spreading depolarizations (SD) are slow waves of complete depolarization of brain tissue followed by neuronal silencing that may play a role in seizure termination. Even though SD was first discovered in the context of epilepsy research, the link between SD and epileptic activity remains understudied. Both seizures and SD share fundamental pathophysiological features, and recent evidence highlights the frequent occurrence of SD in experimental seizure models. Human data on co-occurring seizures and SD are limited but suggestive. This mini-review addresses possible roles of SD during epileptiform activity, shedding light on SD as a potential mechanism for terminating epileptiform activity. A common denominator for many forms of epilepsy is reactive astrogliosis, a process characterized by morphological and functional changes to astrocytes. Data suggest that SD mechanisms are potentially perturbed in reactive astrogliosis and we propose that this may affect seizure pathophysiology.
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Affiliation(s)
- Rune Enger
- Letten Centre and GliaLab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Kjell Heuser
- Department of Neurology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
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2
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Pinares-Garcia P, Spyrou J, McKenzie CE, Forster IC, Soh MS, Mohamed Syazwan E, Atif M, Reid CA. Antidepressant-like activity of a brain penetrant HCN channel inhibitor in mice. Front Pharmacol 2023; 14:1159527. [PMID: 37234718 PMCID: PMC10206048 DOI: 10.3389/fphar.2023.1159527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 04/27/2023] [Indexed: 05/28/2023] Open
Abstract
Changes in Hyperpolarization-Activated Cyclic Nucleotide-Gated (HCN) channel function have been linked to depressive-like traits, making them potential drug targets. However, there is currently no peer-reviewed data supporting the use of a small molecule modulator of HCN channels in depression treatment. Org 34167, a benzisoxazole derivative, has been patented for the treatment of depression and progressed to Phase I trials. In the current study, we analysed the biophysical effects of Org 34167 on HCN channels in stably transfected human embryonic kidney 293 (HEK293) cells and mouse layer V neurons using patch-clamp electrophysiology, and we utilised three high-throughput screens for depressive-like behaviour to assess the activity of Org 34167 in mice. The impact of Org 34167 on locomotion and coordination were measured by performing rotarod and ledged beam tests. Org 34167 is a broad-spectrum inhibitor of HCN channels, slowing activation and causing a hyperpolarising shift in voltage-dependence of activation. It also reduced I h-mediated sag in mouse neurons. Org 34167 (0.5 mg/kg) reduced marble burying and increased the time spent mobile in the Porsolt swim and tail suspension tests in both male and female BALB/c mice, suggesting reduced depressive-like behaviour. Although no adverse effects were seen at 0.5 mg/kg, an increase in dose to 1 mg/kg resulted in visible tremors and impaired locomotion and coordination. These data support the premise that HCN channels are valid targets for anti-depressive drugs albeit with a narrow therapeutic index. Drugs with higher HCN subtype selectivity are needed to establish if a wider therapeutic window can be obtained.
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Affiliation(s)
- Paulo Pinares-Garcia
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - James Spyrou
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - Chaseley E. McKenzie
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - Ian C. Forster
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - Ming S. Soh
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - Erlina Mohamed Syazwan
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - Mohammed Atif
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - Christopher A. Reid
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Heidelberg, VIC, Australia
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Volobueva MN, Suleymanova EM, Smirnova MP, Bolshakov AP, Vinogradova LV. A Single Episode of Cortical Spreading Depolarization Increases mRNA Levels of Proinflammatory Cytokines, Calcitonin Gene-Related Peptide and Pannexin-1 Channels in the Cerebral Cortex. Int J Mol Sci 2022; 24:ijms24010085. [PMID: 36613527 PMCID: PMC9820231 DOI: 10.3390/ijms24010085] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/01/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
Cortical spreading depolarization (CSD) is the neuronal correlate of migraine aura and the reliable consequence of acute brain injury. The role of CSD in triggering headaches that follow migraine aura and brain injury remains to be uncertain. We examined whether a single CSD occurring in awake animals modified the expression of proinflammatory cytokines (Il1b, TNF, and Il6) and endogenous mediators of nociception/neuroinflammation-pannexin 1 (Panx1) channel and calcitonin gene-related peptide (CGRP), transforming growth factor beta (TGFb) in the cortex. Unilateral microinjury of the somatosensory cortex triggering a single CSD was produced in awake Wistar rats. Three hours later, tissue samples from the lesioned cortex, intact ipsilesional cortex invaded by CSD, and homologous areas of the contralateral sham-treated cortex were harvested and analyzed using qPCR. Three hours post-injury, intact CSD-exposed cortexes increased TNF, Il1b, Panx1, and CGRP mRNA levels. The strongest upregulation of proinflammatory cytokines was observed at the injury site, while CGRP and Panx1 were upregulated more strongly in the intact cortexes invaded by CSD. A single CSD is sufficient to produce low-grade parenchymal neuroinflammation with simultaneous overexpression of Panx1 and CGRP. The CSD-induced molecular changes may contribute to pathogenic mechanisms of migraine pain and post-injury headache.
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Affiliation(s)
- Maria N. Volobueva
- Department of Molecular Neurobiology, Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Butlerova Street 5A, 117485 Moscow, Russia
| | - Elena M. Suleymanova
- Department of Molecular Neurobiology, Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Butlerova Street 5A, 117485 Moscow, Russia
| | - Maria P. Smirnova
- Department of Conditioned Reflexes and Physiology of Emotion, Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Butlerova Street 5A, 117485 Moscow, Russia
| | - Alexey P. Bolshakov
- Department of Molecular Neurobiology, Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Butlerova Street 5A, 117485 Moscow, Russia
| | - Lyudmila V. Vinogradova
- Department of Molecular Neurobiology, Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Butlerova Street 5A, 117485 Moscow, Russia
- Correspondence: or
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Smirnova MP, Medvedeva TM, Pavlova IV, Vinogradova LV. Region-Specific Vulnerability of the Amygdala to Injury-Induced Spreading Depolarization. Biomedicines 2022; 10:biomedicines10092183. [PMID: 36140284 PMCID: PMC9496012 DOI: 10.3390/biomedicines10092183] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 08/29/2022] [Accepted: 08/31/2022] [Indexed: 11/16/2022] Open
Abstract
Spreading depolarization (SD), a self-propagated wave of transient depolarization, regularly occurs in the cortex after acute brain insults and is now referred as an important diagnostic and therapeutic target in patients with acute brain injury. Here, we show that the amygdala, the limbic structure responsible for post-injury neuropsychological symptoms, exhibits strong regional heterogeneity in vulnerability to SD with high susceptibility of its basolateral (BLA) region and resilience of its centromedial (CMA) region to triggering SD by acute focal damage. The BLA micro-injury elicited SD twice as often compared with identical injury of the CMA region (71% vs. 33%). Spatiotemporal features of SDs triggered in the amygdala indicated diverse patterns of the SD propagation to the cortex. Our results suggest that even relatively small cerebral structures can exhibit regional gradients in their susceptibility to SD and the heterogeneity may contribute to the generation of complex SD patterns in the injured brain.
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Tret’yakova LV, Kvichansky AA, Bolshakov AP, Gulyaeva NV. Dexamethasone Modulates Lipopolysaccharide-Induced Expression of Proinflammatory Cytokines in Rat Hippocampus. NEUROCHEM J+ 2021. [DOI: 10.1134/s1819712421330011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Tamim I, Chung DY, de Morais AL, Loonen ICM, Qin T, Misra A, Schlunk F, Endres M, Schiff SJ, Ayata C. Spreading depression as an innate antiseizure mechanism. Nat Commun 2021; 12:2206. [PMID: 33850125 PMCID: PMC8044138 DOI: 10.1038/s41467-021-22464-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 03/15/2021] [Indexed: 12/16/2022] Open
Abstract
Spreading depression (SD) is an intense and prolonged depolarization in the central nervous systems from insect to man. It is implicated in neurological disorders such as migraine and brain injury. Here, using an in vivo mouse model of focal neocortical seizures, we show that SD may be a fundamental defense against seizures. Seizures induced by topical 4-aminopyridine, penicillin or bicuculline, or systemic kainic acid, culminated in SDs at a variable rate. Greater seizure power and area of recruitment predicted SD. Once triggered, SD immediately suppressed the seizure. Optogenetic or KCl-induced SDs had similar antiseizure effect sustained for more than 30 min. Conversely, pharmacologically inhibiting SD occurrence during a focal seizure facilitated seizure generalization. Altogether, our data indicate that seizures trigger SD, which then terminates the seizure and prevents its generalization.
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Affiliation(s)
- Isra Tamim
- Neurovascular Research Unit, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Charité-Universitätsmedizin Berlin, Klinik und Hochschulambulanz für Neurologie und Centrum für Schlaganfallforschung Berlin (CSB), Berlin, Germany
| | - David Y Chung
- Neurovascular Research Unit, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Andreia Lopes de Morais
- Neurovascular Research Unit, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Inge C M Loonen
- Neurovascular Research Unit, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Tao Qin
- Neurovascular Research Unit, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Amrit Misra
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Frieder Schlunk
- Charité-Universitätsmedizin Berlin, Klinik und Hochschulambulanz für Neurologie und Centrum für Schlaganfallforschung Berlin (CSB), Berlin, Germany
| | - Matthias Endres
- Charité-Universitätsmedizin Berlin, Klinik und Hochschulambulanz für Neurologie und Centrum für Schlaganfallforschung Berlin (CSB), Berlin, Germany
| | - Steven J Schiff
- Center for Neural Engineering, Departments of Engineering Science and Mechanics and Physics, The Pennsylvania State University, State College, PA, USA
| | - Cenk Ayata
- Neurovascular Research Unit, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
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Vinogradova LV, Rysakova MP, Pavlova IV. Small damage of brain parenchyma reliably triggers spreading depolarization. Neurol Res 2020; 42:76-82. [DOI: 10.1080/01616412.2019.1709745] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Lyudmila V. Vinogradova
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
| | - Maria P. Rysakova
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
| | - Irina V Pavlova
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
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Zakharov A, Chernova K, Burkhanova G, Holmes GL, Khazipov R. Segregation of seizures and spreading depolarization across cortical layers. Epilepsia 2019; 60:2386-2397. [PMID: 31755112 DOI: 10.1111/epi.16390] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 10/25/2019] [Accepted: 10/25/2019] [Indexed: 01/13/2023]
Abstract
OBJECTIVE Cortical spreading depolarization (SD) and seizures are often co-occurring electrophysiological phenomena. However, the cross-layer dynamics of SD during seizures and the effect of SD on epileptic activity across cortical layers remain largely unknown. METHODS We explored the spatial-temporal dynamics of SD and epileptic activity across layers of the rat barrel cortex using direct current silicone probe recordings during flurothyl-induced seizures. RESULTS SD occurred in half of the flurothyl-evoked seizures. SD always started from the superficial layers and spread downward either through all cortical layers or stopping at the L4/L5 border. In cases without SD, seizures were characterized by synchronized population firing across all cortical layers throughout the entire seizure. However, when SD occurred, epileptic activity was transiently silenced in layers involved with SD but persisted in deeper layers. During partial SD, epileptiform activity persisted in deep layers throughout the entire seizure, with positive signals at the cortical surface reflecting passive sources of population spikes generated in deeper cortical layers. During full SD, the initial phase of SD propagation through the superficial layers was similar to partial SD, with suppression of activity at the superficial layers and segregation of seizures to deep layers. Further propagation of SD to deep layers resulted in a wave of transient suppression of epileptic activity through the entire cortical column. Thus, vertical propagation of SD through the cortical column creates dynamic network states during which epileptiform activity is restricted to layers without SD. SIGNIFICANCE Our results point to the importance of vertical SD spread in the SD-related depression of epileptiform activity across cortical layers.
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Affiliation(s)
- Andrey Zakharov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia.,Department of physiology, Kazan State Medical University, Kazan, Russia
| | - Kseniya Chernova
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
| | | | - Gregory L Holmes
- Department of Neurological Sciences, Larner College of Medicine, University of Vermont, Burlington, Vermont
| | - Roustem Khazipov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia.,Mediterranean Institute of Neurobiology, National Institute of Health and Medical Research Mixed Unit of Research 1249, Aix-Marseille University, Marseille, France
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Cozzolino O, Marchese M, Trovato F, Pracucci E, Ratto GM, Buzzi MG, Sicca F, Santorelli FM. Understanding Spreading Depression from Headache to Sudden Unexpected Death. Front Neurol 2018; 9:19. [PMID: 29449828 PMCID: PMC5799941 DOI: 10.3389/fneur.2018.00019] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 01/11/2018] [Indexed: 01/03/2023] Open
Abstract
Spreading depression (SD) is a neurophysiological phenomenon characterized by abrupt changes in intracellular ion gradients and sustained depolarization of neurons. It leads to loss of electrical activity, changes in the synaptic architecture, and an altered vascular response. Although SD is often described as a unique phenomenon with homogeneous characteristics, it may be strongly affected by the particular triggering event and by genetic background. Furthermore, SD may contribute differently to the pathogenesis of widely heterogeneous clinical conditions. Indeed, clinical disorders related to SD vary in their presentation and severity, ranging from benign headache conditions (migraine syndromes) to severely disabling events, such as cerebral ischemia, or even death in people with epilepsy. Although the characteristics and mechanisms of SD have been dissected using a variety of approaches, ranging from cells to human models, this phenomenon remains only partially understood because of its complexity and the difficulty of obtaining direct experimental data. Currently, clinical monitoring of SD is limited to patients who require neurosurgical interventions and the placement of subdural electrode strips. Significantly, SD events recorded in humans display electrophysiological features that are essentially the same as those observed in animal models. Further research using existing and new experimental models of SD may allow a better understanding of its core mechanisms, and of their differences in different clinical conditions, fostering opportunities to identify and develop targeted therapies for SD-related disorders and their worst consequences.
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Affiliation(s)
- Olga Cozzolino
- NEST, Istituto Nanoscienze CNR and Scuola Normale Superiore, Pisa, Italy
| | - Maria Marchese
- Molecular Medicine and Clinical Neurophysiology Laboratories, Department of Developmental Neuroscience, IRCCS Fondazione Stella Maris, Pisa, Italy
| | - Francesco Trovato
- NEST, Istituto Nanoscienze CNR and Scuola Normale Superiore, Pisa, Italy
| | - Enrico Pracucci
- NEST, Istituto Nanoscienze CNR and Scuola Normale Superiore, Pisa, Italy
| | - Gian Michele Ratto
- NEST, Istituto Nanoscienze CNR and Scuola Normale Superiore, Pisa, Italy
| | | | - Federico Sicca
- Molecular Medicine and Clinical Neurophysiology Laboratories, Department of Developmental Neuroscience, IRCCS Fondazione Stella Maris, Pisa, Italy
| | - Filippo M Santorelli
- Molecular Medicine and Clinical Neurophysiology Laboratories, Department of Developmental Neuroscience, IRCCS Fondazione Stella Maris, Pisa, Italy
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Kramer DR, Fujii T, Ohiorhenuan I, Liu CY. Interplay between Cortical Spreading Depolarization and Seizures. Stereotact Funct Neurosurg 2017; 95:1-5. [PMID: 28088802 DOI: 10.1159/000452841] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 10/18/2016] [Indexed: 11/19/2022]
Abstract
Cortical spreading depolarization (CSD) is an electrophysiologic phenomenon found mostly in the setting of neurologic injury resulting in the disturbance of ion homeostasis and leading to changes in the local vascular response. The bioelectric etiology of CSD shares similarities to those in epileptic disorders, yet the relationship between seizures and CSD is unclear, with several studies observing cortical depression before, during, and after seizure activity, thus obscuring our understanding of whether CSD activity potentiates or limits seizures and vice versa. Cortical sampling has exhibited how the redistribution of ion concentrations in the intra- and extracellular environments interplay between the excitation of seizures and the electrical depression of CSD. Modeling of both environments has suggested that CSD synchronizes the affected tissue, creating a favorable environment for seizure activity; however, other studies have demonstrated the opposite: epileptiform activity initiating waves of CSD. Further studies have underscored the role of the vascular response and subsequent ischemia in CSD that contributes to epileptogenesis. Investigations in migraine, traumatic brain injury, and other neurologic injuries suggest that several drugs may target CSD. Manipulations in the occurrence and nature of CSD can potentially alter the threshold for seizure activity, and perhaps minimize immediate and long-term sequelae associated with epilepsy.
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Affiliation(s)
- Daniel R Kramer
- Department of Neurosurgery, University of Southern California, Los Angeles, CA, USA
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Scicchitano F, van Rijn CM, van Luijtelaar G. Unilateral and Bilateral Cortical Resection: Effects on Spike-Wave Discharges in a Genetic Absence Epilepsy Model. PLoS One 2015; 10:e0133594. [PMID: 26262879 PMCID: PMC4532477 DOI: 10.1371/journal.pone.0133594] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 06/29/2015] [Indexed: 12/28/2022] Open
Abstract
Research Question Recent discoveries have challenged the traditional view that the thalamus is the primary source driving spike-and-wave discharges (SWDs). At odds, SWDs in genetic absence models have a cortical focal origin in the deep layers of the perioral region of the somatosensory cortex. The present study examines the effect of unilateral and bilateral surgical resection of the assumed focal cortical region on the occurrence of SWDs in anesthetized WAG/Rij rats, a well described and validated genetic absence model. Methods Male WAG/Rij rats were used: 9 in the resected and 6 in the control group. EEG recordings were made before and after craniectomy, after unilateral and after bilateral removal of the focal region. Results SWDs decreased after unilateral cortical resection, while SWDs were no longer noticed after bilateral resection. This was also the case when the resected areas were restricted to layers I-IV with layers V and VI intact. Conclusions These results suggest that SWDs are completely abolished after bilateral removal of the focal region, most likely by interference with an intracortical columnar circuit. The evidence suggests that absence epilepsy is a network type of epilepsy since interference with only the local cortical network abolishes all seizures.
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Affiliation(s)
- Francesca Scicchitano
- Department of Health Science, School of Medicine and Surgery, University “Magna Graecia” of Catanzaro, Viale Europa—Germaneto, 88100, Catanzaro, Italy
| | - Clementina M. van Rijn
- Department of Biological Psychology, Donders Centre for Cognition, Donders Institution of Brain, Cognition and Behavior, Radboud University, Nijmegen, The Netherlands
| | - Gilles van Luijtelaar
- Department of Biological Psychology, Donders Centre for Cognition, Donders Institution of Brain, Cognition and Behavior, Radboud University, Nijmegen, The Netherlands
- * E-mail:
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D'Amore V, von Randow C, Nicoletti F, Ngomba RT, van Luijtelaar G. Anti-absence activity of mGlu1 and mGlu5 receptor enhancers and their interaction with a GABA reuptake inhibitor: Effect of local infusions in the somatosensory cortex and thalamus. Epilepsia 2015; 56:1141-51. [PMID: 26040777 DOI: 10.1111/epi.13024] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/06/2015] [Indexed: 12/13/2022]
Abstract
OBJECTIVE Glutamate and γ-aminobutyric acid (GABA) are the key neurotransmitter systems in the cortical-thalamocortical network, involved in normal and pathologic oscillations such as spike-wave discharges (SWDs), which characterize different forms of absence epilepsy. Metabotropic glutamate (mGlu) and GABA receptors are widely expressed within this network. Herein, we examined the effects of two selective positive allosteric modulators (PAMs) of mGlu1 and mGlu5 receptors, the GABA reuptake inhibitor, tiagabine, and their interaction in the somatosensory cortex and thalamus on SWDs in WAG/Rij rats. METHODS Male WAG/Rij rats were equipped with bilateral cannulas in the somatosensory cortex (S1po) or the ventrobasal (VB) thalamic nuclei, and with cortical electroencephalography (EEG) electrodes. Rats received a single dose of the mGlu1 receptor PAM, RO0711401, or the mGlu5 receptor PAM, VU0360172, various doses of tiagabine, or VU0360172 combined with tiagabine. RESULTS Both PAMs suppressed SWDs regardless of the site of injection. Tiagabine enhanced SWDs when injected into the thalamus, but, unexpectedly, suppressed SWDs in a dose-dependent manner when injected into the cortex. Intracortical co-injection of VU0360172 and tiagabine produced slightly larger effects as compared to either VU0360172 or tiagabine alone. Intrathalamic co-injections of VU0360172 and subthreshold doses of tiagabine caused an antiabsence effect similar to that exhibited by VU0360172 alone in the first 10 min. At 30 min, however, the antiabsence effect of VU0360172 was prevented by subthreshold doses of tiagabine, and the combination produced a paradoxical proabsence effect at 40 and 50 min. SIGNIFICANCE These data (1) show that mGlu1 and mGlu5 receptor PAMs reduce absence seizures acting at both thalamic and cortical levels; (2) demonstrate for the first time that tiagabine, despite its established absence-enhancing effect, reduces SWDs when injected into the somatosensory cortex; and (3) indicate that the efficacy of VU0360172 in the thalamus may be critically affected by the availability of (extra)synaptic GABA.
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Affiliation(s)
| | - Constanze von Randow
- Donders Centre for Cognition, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Ferdinando Nicoletti
- IRCCS Neuromed, Pozzilli, Italy.,Department of Physiology and Pharmacology, Sapienza University, Rome, Italy
| | | | - Gilles van Luijtelaar
- Donders Centre for Cognition, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands
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Broberg M, Pope KJ, Olsson T, Shuttleworth CW, Willoughby JO. Spreading depression: Evidence of five electroencephalogram phases. J Neurosci Res 2014; 92:1384-94. [DOI: 10.1002/jnr.23412] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 03/05/2014] [Accepted: 04/15/2014] [Indexed: 11/11/2022]
Affiliation(s)
- Marita Broberg
- Center for Neuroscience and Department of Neurology; Flinders University; Adelaide South Australia Australia
| | - Kenneth J. Pope
- School of Informatics and Engineering; Flinders University; Adelaide South Australia Australia
| | - Torsten Olsson
- Department of Signals and Systems; Chalmers University of Technology; Göteborg Sweden
| | - C. William Shuttleworth
- Department of Neurosciences; University of New Mexico School of Medicine; Albuquerque New Mexico
| | - John O. Willoughby
- Center for Neuroscience and Department of Neurology; Flinders University; Adelaide South Australia Australia
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