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Criscuolo C, Chartampila E, Ginsberg SD, Scharfman HE. Stability of dentate gyrus granule cell mossy fiber BDNF protein expression with age and resistance of granule cells to Alzheimer's disease neuropathology in a mouse model. bioRxiv 2023:2023.05.07.539742. [PMID: 37214931 PMCID: PMC10197599 DOI: 10.1101/2023.05.07.539742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The neurotrophin brain-derived neurotrophic factor (BDNF) is important in development and maintenance of neurons and their plasticity. Hippocampal BDNF has been implicated Alzheimer's disease (AD) because hippocampal levels in AD patients and AD animal models are consistently downregulated, suggesting that reduced BDNF contributes to AD. However, the location where hippocampal BDNF protein is most highly expressed, the mossy fiber (MF) axons of dentate gyrus (DG) granule cells (GCs), has been understudied, and never in controlled in vivo conditions. We examined MF BDNF protein in the Tg2576 mouse model of AD. Tg2576 and wild type (WT) mice of both sexes were examined at 2-3 months of age, when amyloid-β (Aβ) is present in neurons but plaques are absent, and 11-20 months of age, after plaque accumulation. As shown previously, WT mice exhibited high levels of MF BDNF protein. Interestingly, there was no significant decline with age in either genotype or sex. Notably, we found a correlation between MF BDNF protein and GC ΔFosB, a transcription factor that increases after 1-2 weeks of elevated neuronal activity. Remarkably, there was relatively little evidence of Aβ in GCs or the GC layer even at old ages. Results indicate MF BDNF is stable in the Tg2576 mouse, and MF BDNF may remain unchanged due to increased GC neuronal activity, since BDNF expression is well known to be activity-dependent. The resistance of GCs to long-term Aβ accumulation provides an opportunity to understand how to protect other vulnerable neurons from increased Aβ levels and therefore has translational implications.
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Affiliation(s)
- Chiara Criscuolo
- Center for Dementia Research, the Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, 10962, USA
- Department of Child & Adolescent Psychiatry, New York University Grossman School of Medicine, New York, NY, 10016, USA
| | - Elissavet Chartampila
- Center for Dementia Research, the Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, 10962, USA
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Stephen D Ginsberg
- Center for Dementia Research, the Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, 10962, USA
- Department of Neuroscience & Physiology, New York University Grossman School of Medicine, New York, NY, 10016, USA
- Department of Psychiatry, New York University Grossman School of Medicine, New York, NY, 10016, USA
- NYU Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, 10016, USA
| | - Helen E Scharfman
- Center for Dementia Research, the Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, 10962, USA
- Department of Child & Adolescent Psychiatry, New York University Grossman School of Medicine, New York, NY, 10016, USA
- Department of Neuroscience & Physiology, New York University Grossman School of Medicine, New York, NY, 10016, USA
- NYU Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, 10016, USA
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Lafourcade CA, Sparks FT, Bordey A, Wyneken U, Mohammadi MH. Cannabinoid regulation of neurons in the dentate gyrus during epileptogenesis: Role of CB1R-associated proteins and downstream pathways. Epilepsia 2023. [PMID: 36869624 DOI: 10.1111/epi.17569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 02/27/2023] [Accepted: 03/01/2023] [Indexed: 03/05/2023]
Abstract
The hippocampal formation plays a central role in the development of temporal lobe epilepsy (TLE), a disease characterized by recurrent, unprovoked epileptic discharges. TLE is a neurologic disorder characterized by acute long-lasting seizures (i.e., abnormal electrical activity in the brain) or seizures that occur in close proximity without recovery, typically after a brain injury or status epilepticus. After status epilepticus, epileptogenic hyperexcitability develops gradually over the following months to years, resulting in the emergence of chronic, recurrent seizures. Acting as a filter or gate, the hippocampal dentate gyrus (DG) normally prevents excessive excitation from propagating through the hippocampus, and is considered a critical region in the progression of epileptogenesis in pathological conditions. Importantly, lipid-derived endogenous cannabinoids (endocannabinoids), which are produced on demand as retrograde messengers, are central regulators of neuronal activity in the DG circuit. In this review, we summarize recent findings concerning the role of the DG in controlling hyperexcitability and propose how DG regulation by cannabinoids (CBs) could provide avenues for therapeutic interventions. We also highlight possible pathways and manipulations that could be relevant for the control of hyperexcitation. The use of CB compounds to treat epilepsies is controversial, as anecdotal evidence is not always validated by clinical trials. Recent publications shed light on the importance of the DG as a region regulating incoming hippocampal excitability during epileptogenesis. We review recent findings concerning the modulation of the hippocampal DG circuitry by CBs and discuss putative underlying pathways. A better understanding of the mechanisms by which CBs exert their action during seizures may be useful to improve therapies.
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Affiliation(s)
- Carlos A Lafourcade
- Department of Biological Sciences, Xi'an Jiaotong-Liverpool University, Suzhou, China
| | - Fraser T Sparks
- Department of Neuroscience, Columbia University, New York, New York, USA.,Current: Regeneron Pharmaceuticals, Tarrytown, New York, USA
| | - Angelique Bordey
- Department of Neurosurgery, Yale School of Medicine, New Haven, Connecticut, USA
| | - Ursula Wyneken
- Centro de Investigación e Innovación Biomédica, Laboratorio de Neurociencias, Universidad de Los Andes, Santiago, Chile.,Center of Interventional Medicine for Precision and Advanced Cellular Therapy, Santiago, Chile
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Dohm-Hansen S, Donoso F, Lucassen PJ, Clarke G, Nolan YM. The gut microbiome and adult hippocampal neurogenesis: A new focal point for epilepsy? Neurobiol Dis 2022; 170:105746. [DOI: 10.1016/j.nbd.2022.105746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 04/13/2022] [Accepted: 04/29/2022] [Indexed: 02/07/2023] Open
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Abstract
ΔFOSB is a uniquely stable member of the FOS family of immediate early gene AP1 transcription factors. Its accumulation in specific cell types and tissues in response to a range of chronic stimuli is associated with biological phenomena as diverse as memory formation, drug addiction, stress resilience, and immune cell activity. Causal connections between ΔFOSB expression and the physiological and behavioral sequelae of chronic stimuli have been established in rodent and, in some cases, primate models for numerous healthy and pathological states with such preclinical observations often supported by human data demonstrating tissue-specific ΔFOSB expression associated with several specific syndromes. However, the viability of ΔFOSB as a target for therapeutic intervention might be questioned over presumptive concerns of side effects given its expression in such a wide range of cell types and circumstances. Here, we summarize numerous insights from the past three decades of research into ΔFOSB structure, function, mechanisms of induction, and regulation of target genes that support its potential as a druggable target. We pay particular attention to the potential for targeting distinct ΔFOSB isoforms or distinct ΔFOSB-containing multiprotein complexes to achieve cell type or tissue specificity to overcome off-target concerns. We also cover critical gaps in knowledge that currently limit the exploitation of ΔFOSB's therapeutic possibilities and how they may be addressed. Finally, we summarize both current and potential future strategies for generating small molecules or genetic tools for the manipulation of ΔFOSB in the clinic.
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Affiliation(s)
- Alfred J Robison
- Department of Physiology, Michigan State University, East Lansing, Michigan 48824, United States
| | - Eric J Nestler
- Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029, United States
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Righes Marafiga J, Vendramin Pasquetti M, Calcagnotto ME. In vitro Oscillation Patterns Throughout the Hippocampal Formation in a Rodent Model of Epilepsy. Neuroscience 2021; 479:1-21. [PMID: 34710537 DOI: 10.1016/j.neuroscience.2021.10.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 10/14/2021] [Accepted: 10/18/2021] [Indexed: 11/29/2022]
Abstract
Specific oscillatory patterns are considered biomarkers of pathological neuronal network in brain diseases, such as epilepsy. However, the dynamics of underlying oscillations during the epileptogenesis throughout the hippocampal formation in the temporal lobe epilepsy is not clear. Here, we characterized in vitro oscillatory patterns within the hippocampal formation of epileptic rats, under 4-aminopyridine (4-AP)-induced hyperexcitability and during the spontaneous network activity, at two periods of epileptogenesis. First, at the beginning of epileptic chronic phase, 30 days post-pilocarpine-induced Status Epilepticus (SE). Second, at the established epilepsy, 60 days post-SE. The 4-AP-bathed slices from epileptic rats had increased susceptibility to ictogenesis in CA1 at 30 days post-SE, and in entorhinal cortex and dentate gyrus at 60 days post-SE. Higher power and phase coherence were detected mainly for gamma and/or high frequency oscillations (HFOs), in a region- and stage-specific manner. Interestingly, under spontaneous network activity, even without 4-AP-induced hyperexcitability, slices from epileptic animals already exhibited higher power of gamma and HFOs in different areas of hippocampal formation at both periods of epileptogenesis, and higher phase coherence in fast ripples at 60 days post-SE. These findings reinforce the critical role of gamma and HFOs in each one of the hippocampal formation areas during ongoing neuropathological processes, tuning the neuronal network to epilepsy.
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Affiliation(s)
- Joseane Righes Marafiga
- Neurophysiology and Neurochemistry of Neuronal Excitability and Synaptic Plasticity Laboratory (NNNESP Lab.), Department of Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul, Porto Alegre 90035-003, RS, Brazil; Graduate Program in Biological Science: Biochemistry, Universidade Federal do Rio Grande do Sul, Porto Alegre 90035-003, RS, Brazil
| | - Mayara Vendramin Pasquetti
- Neurophysiology and Neurochemistry of Neuronal Excitability and Synaptic Plasticity Laboratory (NNNESP Lab.), Department of Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul, Porto Alegre 90035-003, RS, Brazil; Graduate Program in Biological Science: Biochemistry, Universidade Federal do Rio Grande do Sul, Porto Alegre 90035-003, RS, Brazil
| | - Maria Elisa Calcagnotto
- Neurophysiology and Neurochemistry of Neuronal Excitability and Synaptic Plasticity Laboratory (NNNESP Lab.), Department of Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul, Porto Alegre 90035-003, RS, Brazil; Graduate Program in Biological Science: Biochemistry, Universidade Federal do Rio Grande do Sul, Porto Alegre 90035-003, RS, Brazil.
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Sutton NM, Ascoli GA. Spiking Neural Networks and Hippocampal Function: A Web-Accessible Survey of Simulations, Modeling Methods, and Underlying Theories. COGN SYST RES 2021; 70:80-92. [PMID: 34504394 DOI: 10.1016/j.cogsys.2021.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Computational modeling has contributed to hippocampal research in a wide variety of ways and through a large diversity of approaches, reflecting the many advanced cognitive roles of this brain region. The intensively studied neuron type circuitry of the hippocampus is a particularly conducive substrate for spiking neural models. Here we present an online knowledge base of spiking neural network simulations of hippocampal functions. First, we overview theories involving the hippocampal formation in subjects such as spatial representation, learning, and memory. Then we describe an original literature mining process to organize published reports in various key aspects, including: (i) subject area (e.g., navigation, pattern completion, epilepsy); (ii) level of modeling detail (Hodgkin-Huxley, integrate-and-fire, etc.); and (iii) theoretical framework (attractor dynamics, oscillatory interference, self-organizing maps, and others). Moreover, every peer-reviewed publication is also annotated to indicate the specific neuron types represented in the network simulation, establishing a direct link with the Hippocampome.org portal. The web interface of the knowledge base enables dynamic content browsing and advanced searches, and consistently presents evidence supporting every annotation. Moreover, users are given access to several types of statistical reports about the collection, a selection of which is summarized in this paper. This open access resource thus provides an interactive platform to survey spiking neural network models of hippocampal functions, compare available computational methods, and foster ideas for suitable new directions of research.
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Affiliation(s)
- Nate M Sutton
- Department of Bioengineering, 4400 University Drive, George Mason University, Fairfax, Virginia, 22030 (USA)
| | - Giorgio A Ascoli
- Department of Bioengineering, 4400 University Drive, George Mason University, Fairfax, Virginia, 22030 (USA).,Interdepartmental Neuroscience Program, 4400 University Drive, George Mason University, Fairfax, Virginia, 22030 (USA)
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Lévesque M, Biagini G, de Curtis M, Gnatkovsky V, Pitsch J, Wang S, Avoli M. The pilocarpine model of mesial temporal lobe epilepsy: Over one decade later, with more rodent species and new investigative approaches. Neurosci Biobehav Rev 2021; 130:274-291. [PMID: 34437936 DOI: 10.1016/j.neubiorev.2021.08.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 08/17/2021] [Accepted: 08/21/2021] [Indexed: 01/19/2023]
Abstract
Fundamental work on the mechanisms leading to focal epileptic discharges in mesial temporal lobe epilepsy (MTLE) often rests on the use of rodent models in which an initial status epilepticus (SE) is induced by kainic acid or pilocarpine. In 2008 we reviewed how, following systemic injection of pilocarpine, the main subsequent events are the initial SE, the latent period, and the chronic epileptic state. Up to a decade ago, rats were most often employed and they were frequently analysed only behaviorally. However, the use of transgenic mice has revealed novel information regarding this animal model. Here, we review recent findings showing the existence of specific neuronal events during both latent and chronic states, and how optogenetic activation of specific cell populations modulate spontaneous seizures. We also address neuronal damage induced by pilocarpine treatment, the role of neuroinflammation, and the influence of circadian and estrous cycles. Updating these findings leads us to propose that the rodent pilocarpine model continues to represent a valuable tool for identifying the basic pathophysiology of MTLE.
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Affiliation(s)
- Maxime Lévesque
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery, McGill University, Montreal, QC, H3A 2B4, Canada
| | - Giuseppe Biagini
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena & Reggio Emilia, 41100 Modena, Italy
| | - Marco de Curtis
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milano, Italy
| | - Vadym Gnatkovsky
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milano, Italy; Department of Epileptology, University Hospital Bonn, 53127 Bonn, Germany
| | - Julika Pitsch
- Department of Epileptology, University Hospital Bonn, 53127 Bonn, Germany
| | - Siyan Wang
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery, McGill University, Montreal, QC, H3A 2B4, Canada
| | - Massimo Avoli
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery, McGill University, Montreal, QC, H3A 2B4, Canada; Departments of Physiology, McGill University, Montreal, QC, H3A 2B4, Canada; Department of Experimental Medicine, Sapienza University of Rome, 00185 Roma, Italy.
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Abstract
The subicular complex (hereafter referred as subiculum), which is reciprocally connected with the hippocampus and rhinal cortices, exerts a major control on hippocampal outputs. Over the last three decades, several studies have revealed that the subiculum plays a pivotal role in learning and memory but also in pathological conditions such as mesial temporal lobe epilepsy (MTLE). Indeed, subicular networks actively contribute to seizure generation and this structure is relatively spared from the cell loss encountered in this focal epileptic disorder. In this review, we will address: (i) the functional properties of subicular principal cells under normal and pathological conditions; (ii) the subiculum role in sustaining seizures in in vivo models of MTLE and in in vitro models of epileptiform synchronization; (iii) its presumptive role in human MTLE; and (iv) evidence underscoring the relationship between subiculum and antiepileptic drug effects. The studies reviewed here reinforce the view that the subiculum represents a limbic area with relevant, as yet unexplored, roles in focal epilepsy.
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Affiliation(s)
- Maxime Lévesque
- Departments of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, 3801 University Street, Montreal, H3A 2B4Québec, Canada
| | - Massimo Avoli
- Departments of Neurology, Neurosurgery, and Physiology, Montreal Neurological Institute-Hospital, McGill University, 3801 University Street, Montreal, H3A 2B4Québec, Canada
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Kapucu A, Üzüm G, Kaptan Z, Akgün-Dar K. Effects of erythropoietin pretreatment on single dose pentylentetrazole-induced seizures in rats. Biotech Histochem 2020; 95:418-427. [DOI: 10.1080/10520295.2020.1713398] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- Ayşegul Kapucu
- Department of Biology, Faculty of Science, Istanbul University, Istanbul, Turkey
| | - Gülay Üzüm
- Department of Physiology, Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Zülal Kaptan
- Department of Physiology, Faculty of Medicine, Beykent University, Istanbul, Turkey
| | - Kadriye Akgün-Dar
- Department of Biology, Faculty of Science, Istanbul University, Istanbul, Turkey
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Chernigovskaya EV, Korotkov AA, Dorofeeva NA, Gorbacheva EL, Kulikov AA, Glazova MV. Delayed audiogenic seizure development in a genetic rat model is associated with overactivation of ERK1/2 and disturbances in glutamatergic signaling. Epilepsy Behav 2019; 99:106494. [PMID: 31493733 DOI: 10.1016/j.yebeh.2019.106494] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 08/13/2019] [Accepted: 08/13/2019] [Indexed: 02/05/2023]
Abstract
Krushinsky-Molodkina (KM) rats genetically prone to audiogenic seizure are characterized by age-dependent expression of audiogenic seizures (AGS). It is known that the critical period of enhanced seizure susceptibility in rodents occurs at 2nd-3rd weeks of postnatal development. However, KM rats do not express AGS at this time-point, but start to demonstrate a stable AGS only after the age of 3 months. We hypothesized that this delay in AGS susceptibility in KM rats is genetically determined and may depend on some alterations in the development of the hippocampal glutamatergic system during the early postnatal period. We analyzed the expression and activity of seizure-related proteins, such as vesicular glutamate transporter 2 (VGLUT2), extracellular signal-regulated kinases 1 and 2 (ERK1/2), synapsin I, and NR2B subunit of the N-methyl-d-aspartate (NMDA) receptor (NR2B) in the hippocampus of KM rats during postnatal development. A significantly higher activity of ERK1/2 in KM rats was observed at 14th, 30th, and 60th days of postnatal development (P14, P30, P60) in comparison with control Wistar rats of the corresponding ages, while in adult (P120) KM rats it was at the same level with Wistar rats. Despite the increased activity of ERK1/2 at P14 and P30, the phosphorylation of synapsin I at Ser62/67 was significantly lower in the hippocampus of KM rats than in Wistar rats of the same ages; however, at P60 and P120, the phosphorylation of synapsin I was enhanced. Our data also revealed the increase of VGLUT2 and NR2B expression at P14, which dramatically decreased at the later stages. Our data indicate that a genetically determined increase in ERK1/2 kinase activity during postnatal ontogenesis in KM rats may be associated with the disturbances in synthesis and activity of the proteins, which are responsible for glutamatergic transmission in the KM rat hippocampus during the seizure susceptibility development.
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Affiliation(s)
- Elena V Chernigovskaya
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, 44 Thorez pr., 194223 St. Petersburg, Russia
| | - Anatoly A Korotkov
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, 44 Thorez pr., 194223 St. Petersburg, Russia
| | - Nadezhda A Dorofeeva
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, 44 Thorez pr., 194223 St. Petersburg, Russia
| | - Evgenia L Gorbacheva
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, 44 Thorez pr., 194223 St. Petersburg, Russia
| | - Alexey A Kulikov
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, 44 Thorez pr., 194223 St. Petersburg, Russia
| | - Margarita V Glazova
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, 44 Thorez pr., 194223 St. Petersburg, Russia.
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You JC, Stephens GS, Fu CH, Zhang X, Liu Y, Chin J. Genome-wide profiling reveals functional diversification of ∆FosB gene targets in the hippocampus of an Alzheimer's disease mouse model. PLoS One 2018; 13:e0192508. [PMID: 29408867 DOI: 10.1371/journal.pone.0192508] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Accepted: 01/24/2018] [Indexed: 01/20/2023] Open
Abstract
The activity-induced transcription factor ∆FosB has been implicated in Alzheimer’s disease (AD) as a critical regulator of hippocampal function and cognition downstream of seizures and network hyperexcitability. With its long half-life (> 1 week), ∆FosB is well-poised to modulate hippocampal gene expression over extended periods of time, enabling effects to persist even during seizure-free periods. However, the transcriptional mechanisms by which ∆FosB regulates hippocampal function are poorly understood due to lack of identified hippocampal gene targets. To identify putative ∆FosB gene targets, we employed high-throughput sequencing of genomic DNA bound to ∆FosB after chromatin immunoprecipitation (ChIP-sequencing). We compared ChIP-sequencing results from hippocampi of transgenic mice expressing mutant human amyloid precursor protein (APP) and nontransgenic (NTG) wild-type littermates. Surprisingly, only 52 ∆FosB gene targets were shared between NTG and APP mice; the vast majority of targets were unique to one genotype or the other. We also found a functional shift in the repertoire of ∆FosB gene targets between NTG and APP mice. A large number of targets in NTG mice are involved in neurodevelopment and/or cell morphogenesis, whereas in APP mice there is an enrichment of targets involved in regulation of membrane potential and neuronal excitability. RNA-sequencing and quantitative PCR experiments confirmed that expression of putative ∆FosB gene targets were altered in the hippocampus of APP mice. This study provides key insights into functional domains regulated by ∆FosB in the hippocampus, emphasizing remarkably different programs of gene regulation under physiological and pathological conditions.
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Lucchi C, Costa AM, Giordano C, Curia G, Piat M, Leo G, Vinet J, Brunel L, Fehrentz JA, Martinez J, Torsello A, Biagini G. Involvement of PPARγ in the Anticonvulsant Activity of EP-80317, a Ghrelin Receptor Antagonist. Front Pharmacol 2017; 8:676. [PMID: 29018345 PMCID: PMC5614981 DOI: 10.3389/fphar.2017.00676] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 09/08/2017] [Indexed: 02/03/2023] Open
Abstract
Ghrelin, des-acyl ghrelin and other related peptides possess anticonvulsant activities. Although ghrelin and cognate peptides were shown to physiologically regulate only the ghrelin receptor, some of them were pharmacologically proved to activate the peroxisome proliferator-activated receptor gamma (PPARγ) through stimulation of the scavenger receptor CD36 in macrophages. In our study, we challenged the hypothesis that PPARγ could be involved in the anticonvulsant effects of EP-80317, a ghrelin receptor antagonist. For this purpose, we used the PPARγ antagonist GW9662 to evaluate the modulation of EP-80317 anticonvulsant properties in two different models. Firstly, the anticonvulsant effects of EP-80317 were studied in rats treated with pilocarpine to induce status epilepticus (SE). Secondly, the anticonvulsant activity of EP-80317 was ascertained in the repeated 6-Hz corneal stimulation model in mice. Behavioral and video electrocorticographic (ECoG) analyses were performed in both models. We also characterized levels of immunoreactivity for PPARγ in the hippocampus of 6-Hz corneally stimulated mice. EP-80317 predictably antagonized seizures in both models. Pretreatment with GW9662 counteracted almost all EP-80317 effects both in mice and rats. Only the effects of EP-80317 on power spectra of ECoGs recorded during repeated 6-Hz corneal stimulation were practically unaffected by GW9662 administration. Moreover, GW9662 alone produced a decrease in the latency of tonic-clonic seizures and accelerated the onset of SE in rats. Finally, in the hippocampus of mice treated with EP-80317 we found increased levels of PPARγ immunoreactivity. Overall, these results support the hypothesis that PPARγ is able to modulate seizures and mediates the anticonvulsant effects of EP-80317.
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Affiliation(s)
- Chiara Lucchi
- Laboratory of Experimental Epileptology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio EmiliaModena, Italy
| | - Anna M Costa
- Laboratory of Experimental Epileptology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio EmiliaModena, Italy
| | - Carmela Giordano
- Laboratory of Experimental Epileptology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio EmiliaModena, Italy
| | - Giulia Curia
- Laboratory of Experimental Epileptology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio EmiliaModena, Italy
| | - Marika Piat
- Laboratory of Experimental Epileptology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio EmiliaModena, Italy
| | - Giuseppina Leo
- Laboratory of Experimental Epileptology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio EmiliaModena, Italy
| | - Jonathan Vinet
- Laboratory of Experimental Epileptology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio EmiliaModena, Italy
| | - Luc Brunel
- Centre National de la Recherche Scientifique, Max Mousseron Institute of Biomolecules, National School of Chemistry Montpellier, University of MontpellierMontpellier, France
| | - Jean-Alain Fehrentz
- Centre National de la Recherche Scientifique, Max Mousseron Institute of Biomolecules, National School of Chemistry Montpellier, University of MontpellierMontpellier, France
| | - Jean Martinez
- Centre National de la Recherche Scientifique, Max Mousseron Institute of Biomolecules, National School of Chemistry Montpellier, University of MontpellierMontpellier, France
| | - Antonio Torsello
- School of Medicine and Surgery, University of Milano-BicoccaMilan, Italy
| | - Giuseppe Biagini
- Laboratory of Experimental Epileptology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio EmiliaModena, Italy.,Center for Neuroscience and Neurotechnology, University of Modena and Reggio EmiliaModena, Italy
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Giordano C, Costa AM, Lucchi C, Leo G, Brunel L, Fehrentz JA, Martinez J, Torsello A, Biagini G. Progressive Seizure Aggravation in the Repeated 6-Hz Corneal Stimulation Model Is Accompanied by Marked Increase in Hippocampal p-ERK1/2 Immunoreactivity in Neurons. Front Cell Neurosci 2016; 10:281. [PMID: 28018175 PMCID: PMC5159434 DOI: 10.3389/fncel.2016.00281] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 11/24/2016] [Indexed: 12/13/2022] Open
Abstract
The 6-Hz corneal stimulation test is used to screen novel antiepileptic molecules to overcome the problem of drug refractoriness. Although recognized as a standard test, it has been evaluated only recently in the attempt to characterize the putative neuronal networks involved in seizures caused by corneal stimulation. In particular, by recording from the CA1 region we previously established that the hippocampus participates to propagation of seizure activity. However, these findings were not corroborated by using markers of neuronal activation such as FosB/ΔFosB antigens. In view of this discrepancy, we performed new experiments to characterize the changes in levels of phosphorylated extracellular signal-regulated kinases1/2 (p-ERK1/2), which are also used as markers of neuronal activation. To this aim, mice underwent corneal stimulation up to three different times, in three sessions separated by an interval of 3 days. To characterize a group in which seizures could be prevented by pharmacological treatment, we also considered pretreatment with the ghrelin receptor antagonist EP-80317 (330 μg/kg). Control mice were sham-treated. Video electrocorticographic (ECoG) recordings were obtained from mice belonging to each group of treatment. Animals were finally used to characterize the immunoreactivity for FosB/ΔFosB and p-ERK1/2 in the hippocampus. As previously shown, FosB/ΔFosB levels were highly increased throughout the hippocampus by the first induced seizure but, in spite of the progressively increased seizure severity, they were restored to control levels after the third stimulation. At variance, corneal stimulation caused a progressive increase in p-ERK1/2 immunoreactivity all over the hippocampus, especially in CA1, peaking in the third session. Predictably, EP-80317 administration reduced both duration and severity of seizures, prevented the increase in FosB/ΔFosB levels in the first session, and partially counteracted the increase in p-ERK1/2 levels in the third session. The vast majority of p-ERK1/2 immunopositive cells were co-labeled with FosB/ΔFosB antibodies, suggesting the existence of a relationship between the investigated markers in a subpopulation of neurons activated by seizures. These findings suggest that p-ERK1/2 are useful markers to define the aggravation of seizures and the response to anticonvulsant treatments. In particular, p-ERK1/2 expression clearly identified the involvement of hippocampal regions during seizure aggravation in the 6-Hz model.
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Affiliation(s)
- Carmela Giordano
- Laboratory of Experimental Epileptology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio EmiliaModena, Italy; Department of Neurosciences, NOCSAE Hospital, AUSLModena, Italy
| | - Anna M Costa
- Laboratory of Experimental Epileptology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio EmiliaModena, Italy; Department of Neurosciences, NOCSAE Hospital, AUSLModena, Italy
| | - Chiara Lucchi
- Laboratory of Experimental Epileptology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio EmiliaModena, Italy; Department of Neurosciences, NOCSAE Hospital, AUSLModena, Italy
| | - Giuseppina Leo
- Laboratory of Experimental Epileptology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio EmiliaModena, Italy; Department of Neurosciences, NOCSAE Hospital, AUSLModena, Italy
| | - Luc Brunel
- Max Mousseron Institute of Biomolecules, Centre National de la Recherche Scientifique (CNRS), University of Montpellier, École Nationale Supérieure de Chimie de Montpellier (ENSCM) Montpellier, France
| | - Jean-Alain Fehrentz
- Max Mousseron Institute of Biomolecules, Centre National de la Recherche Scientifique (CNRS), University of Montpellier, École Nationale Supérieure de Chimie de Montpellier (ENSCM) Montpellier, France
| | - Jean Martinez
- Max Mousseron Institute of Biomolecules, Centre National de la Recherche Scientifique (CNRS), University of Montpellier, École Nationale Supérieure de Chimie de Montpellier (ENSCM) Montpellier, France
| | - Antonio Torsello
- Department of Medicine and Surgery, University of Milano-Bicocca Monza, Italy
| | - Giuseppe Biagini
- Laboratory of Experimental Epileptology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio EmiliaModena, Italy; Department of Neurosciences, NOCSAE Hospital, AUSLModena, Italy
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Liu Y, Deng Y, Liu H, Yin C, Li X, Gong Q. Hydrogen sulfide ameliorates learning memory impairment in APP/PS1 transgenic mice: A novel mechanism mediated by the activation of Nrf2. Pharmacol Biochem Behav 2016; 150-151:207-16. [PMID: 27883916 DOI: 10.1016/j.pbb.2016.11.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 10/19/2016] [Accepted: 11/09/2016] [Indexed: 01/28/2023]
Abstract
Beta-amyloid (Aβ) plaques and oxidative stress are associated with the pathogenesis of Alzheimer's disease (AD). Hydrogen sulfide (H2S) has been recognized as a cytoprotectant, which improves learning memory impairment and exerts antioxidant effects in neurodegenerative disorders, including AD. The experiment was projected to explore the effects of H2S on cognitive deficits, Aβ levels and possible antioxidant mechanisms. Here, APP/PS1 transgenic mice were injected sodium hydrosulfide (NaHS, a H2S donor, 2.8mg/kg) once a day for three months. It was found that APP/PS1 transgenic mice exhibited cognitive deficits and a large number of senile plaques, along with neurons decrease and Aβ increase. However, intraperitoneal (i.p.) injection of NaHS improved learning memory deficits, decreased the number of senile plaques, Aβ1-40 and Aβ1-42 levels, suppressed neurons loss, together with up-regulated the levels of cystathionine-β-synthase (CBS) and 3-mercaptopyruvate-sulfurtransferase (3MST). Furthermore, the protein levels of beta-amyloid precursor (APP) and beta-secretase 1 (BACE1) were dramatically restrained after administration of H2S. In addition, H2S exerted antioxidant effects via up-regulation nuclear factor erythroid-2-related factor 2 (Nrf2), heme oxygenase-1(HO-1) and glutathione S-transferase (GST). Taken together, these findings suggest that H2S ameliorates learning memory impairment, decreases the number of senile plaques in APP/PS1 mice possibly through inhibition of Aβ production and activation of Nrf2/antioxidant response element (ARE) pathway.
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Li XH, Deng YY, Li F, Shi JS, Gong QH. Neuroprotective effects of sodium hydrosulfide against β-amyloid-induced neurotoxicity. Int J Mol Med 2016; 38:1152-60. [PMID: 27511125 PMCID: PMC5029968 DOI: 10.3892/ijmm.2016.2701] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 07/28/2016] [Indexed: 12/27/2022] Open
Abstract
Alzheimer's disease (AD) is known to be caused by the accumulation of amyloid-β peptide (Aβ). The accumulation of Aβ has been shown to cause learning and memory impairment in rats, and it has been shown that hydrogen sulfide donors, such as sodium hydrosulfide (NaHS) can attenuate these effects. However, the underlying mechanisms have not yet been fully eludicated. This study was designed to investigate whether NaHS attenuates the inflammation and apoptosis induced by Aβ. We demonstrated that NaHS attenuated Aβ25–35-induced neuronal reduction and apoptosis, and inhibited the activation of pro-caspase-3. It also decreased the protein expresion of phosphodiesterase 5 (PDE5) in the hippocampus of the rats. In addition, NaHS upregulated the expression of peroxisome proliferator-activated receptor (PPAR)-α and PPAR-γ, but it did not affect the expression of PPAR-β. Moreover, the Aβ25–35-exposed rats exhibited a decrease in IκB-α degradation and an increase in nuclear factor-κB (NF-κB) p65 phosphorylation levels, whereas these effects were attenuated by NaHS. Our data suggest that NaHS prevents Aβ-induced neurotoxicity via the upregulation of PPAR-α and PPAR-γ and the inhibition of PDE5. Hence NaHS may prove to be beneficial in the treatment of AD.
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Affiliation(s)
- Xiao-Hui Li
- Department of Pharmacology and Key Laboratory of Basic Pharmacology of Ministry of Education, Zunyi Medical University, Zunyi, Guizhou 563000, P.R. China
| | - Yuan-Yuan Deng
- Department of Pharmacology and Key Laboratory of Basic Pharmacology of Ministry of Education, Zunyi Medical University, Zunyi, Guizhou 563000, P.R. China
| | - Fei Li
- Department of Pharmacology and Key Laboratory of Basic Pharmacology of Ministry of Education, Zunyi Medical University, Zunyi, Guizhou 563000, P.R. China
| | - Jing-Shan Shi
- Department of Pharmacology and Key Laboratory of Basic Pharmacology of Ministry of Education, Zunyi Medical University, Zunyi, Guizhou 563000, P.R. China
| | - Qi-Hai Gong
- Department of Pharmacology and Key Laboratory of Basic Pharmacology of Ministry of Education, Zunyi Medical University, Zunyi, Guizhou 563000, P.R. China
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Ma DL, Qu JQ, Goh ELK, Tang FR. Reorganization of Basolateral Amygdala-Subiculum Circuitry in Mouse Epilepsy Model. Front Neuroanat 2016; 9:167. [PMID: 26834577 PMCID: PMC4712303 DOI: 10.3389/fnana.2015.00167] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 12/21/2015] [Indexed: 11/13/2022] Open
Abstract
In this study, we investigated the reorganized basolateral amygdala (BLA)-subiculum pathway in a status epilepticus (SE) mouse model with epileptic episodes induced by pilocarpine. We have previously observed a dramatic loss of neurons in the CA1-3 fields of the hippocampus in epileptic mice. Herein, we observed a 43-57% reduction in the number of neurons in the BLA of epileptic mice. However, injection of an anterograde tracer, Phaseolus vulgaris leucoagglutinin (PHA-L) into the BLA indicated 25.63% increase in the number of PHA-L-immunopositive terminal-like structures in the ventral subiculum (v-Sub) of epileptic mice as compared to control mice. These data suggest that the projections from the basal nucleus at BLA to the vSub in epileptic mice are resistant to epilepsy-induced damage. Consequently, these epileptic mice exhibit partially impairment but not total loss of context-dependent fear memory. Epileptic mice also show increased c-Fos expression in the BLA and vSub when subjected to contextual memory test, suggesting the participation of these two brain areas in foot shock-dependent fear conditioning. These results indicate the presence of functional neural connections between the BLA-vSub regions that participate in learning and memory in epileptic mice.
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Affiliation(s)
- Dong Liang Ma
- Program in Neuroscience and Behavioral Disorder, Duke-NUS Graduate Medical School Singapore, Singapore
| | - Jian Qiang Qu
- Department of Neurosurgery, Second Affiliated Hospital of Xi'an Jiaotong University Xi'an, China
| | - Eyleen L K Goh
- Program in Neuroscience and Behavioral Disorder, Duke-NUS Graduate Medical SchoolSingapore, Singapore; Department of Physiology, Yong Loo Lin School of Medicine, National University of SingaporeSingapore, Singapore; KK Research Center, KK Women's and Children's HospitalSingapore, Singapore
| | - Feng Ru Tang
- Temasek Laboratories, National University of SingaporeSingapore, Singapore; Singapore Nuclear Research and Safety Initiative, National University of SingaporeSingapore, Singapore
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Giordano C, Vinet J, Curia G, Biagini G. Repeated 6-Hz Corneal Stimulation Progressively Increases FosB/ΔFosB Levels in the Lateral Amygdala and Induces Seizure Generalization to the Hippocampus. PLoS One 2015; 10:e0141221. [PMID: 26555229 PMCID: PMC4640822 DOI: 10.1371/journal.pone.0141221] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 10/06/2015] [Indexed: 11/30/2022] Open
Abstract
Exposure to repetitive seizures is known to promote convulsions which depend on specific patterns of network activity. We aimed at evaluating the changes in seizure phenotype and neuronal network activation caused by a modified 6-Hz corneal stimulation model of psychomotor seizures. Mice received up to 4 sessions of 6-Hz corneal stimulation with fixed current amplitude of 32 mA and inter-stimulation interval of 72 h. Video-electroencephalography showed that evoked seizures were characterized by a motor component and a non-motor component. Seizures always appeared in frontal cortex, but only at the fourth stimulation they involved the hippocampus, suggesting the establishment of an epileptogenic process. Duration of seizure non-motor component progressively decreased after the second session, whereas convulsive seizures remained unchanged. In addition, a more severe seizure phenotype, consisting of tonic-clonic generalized convulsions, was predominant after the second session. Immunohistochemistry and double immunofluorescence experiments revealed a significant increase in neuronal activity occurring in the lateral amygdala after the fourth session, most likely due to activity of principal cells. These findings indicate a predominant role of amygdala in promoting progressively more severe convulsions as well as the late recruitment of the hippocampus in the seizure spread. We propose that the repeated 6-Hz corneal stimulation model may be used to investigate some mechanisms of epileptogenesis and to test putative antiepileptogenic drugs.
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MESH Headings
- Animals
- Basolateral Nuclear Complex/metabolism
- Basolateral Nuclear Complex/physiopathology
- Cornea/physiopathology
- Disease Models, Animal
- Electric Stimulation/adverse effects
- Electrodes, Implanted
- Electroencephalography
- Epilepsy, Complex Partial/etiology
- Epilepsy, Complex Partial/genetics
- Epilepsy, Complex Partial/physiopathology
- Epilepsy, Generalized/etiology
- Epilepsy, Generalized/genetics
- Epilepsy, Generalized/physiopathology
- Epilepsy, Tonic-Clonic/etiology
- Epilepsy, Tonic-Clonic/genetics
- Epilepsy, Tonic-Clonic/physiopathology
- Gene Expression Regulation
- Hippocampus/physiopathology
- Male
- Mice
- Microglia/pathology
- Nerve Net/physiopathology
- Nerve Tissue Proteins/biosynthesis
- Nerve Tissue Proteins/genetics
- Neurons/metabolism
- Neurons/pathology
- Phenotype
- Proto-Oncogene Proteins c-fos/biosynthesis
- Proto-Oncogene Proteins c-fos/genetics
- Severity of Illness Index
- Single-Blind Method
- Video Recording
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Affiliation(s)
- Carmela Giordano
- Department of Biomedical, Metabolic and Neural Sciences, Laboratory of Experimental Epileptology, University of Modena and Reggio Emilia, Modena, Italy
| | - Jonathan Vinet
- Department of Biomedical, Metabolic and Neural Sciences, Laboratory of Experimental Epileptology, University of Modena and Reggio Emilia, Modena, Italy
| | - Giulia Curia
- Department of Biomedical, Metabolic and Neural Sciences, Laboratory of Experimental Epileptology, University of Modena and Reggio Emilia, Modena, Italy
| | - Giuseppe Biagini
- Department of Biomedical, Metabolic and Neural Sciences, Laboratory of Experimental Epileptology, University of Modena and Reggio Emilia, Modena, Italy
- Department of Neurosciences, NOCSAE Hospital, AUSL Modena, Italy
- * E-mail:
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Lucchi C, Vinet J, Meletti S, Biagini G. Ischemic-hypoxic mechanisms leading to hippocampal dysfunction as a consequence of status epilepticus. Epilepsy Behav 2015; 49:47-54. [PMID: 25934585 DOI: 10.1016/j.yebeh.2015.04.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 04/01/2015] [Accepted: 04/02/2015] [Indexed: 10/23/2022]
Abstract
Status epilepticus (SE) is one of the recognized primary precipitating events that can lead to temporal lobe epilepsy (TLE) associated with hippocampal sclerosis. This type of epilepsy is characterized by poor response to drug treatment, often requiring surgical intervention to remove the mesial temporal regions involved in the seizure onset. However, even neurosurgery may not be completely successful. Thus, the prevention of hippocampal damage and epileptogenesis is currently evaluated as a possible alternative therapeutic approach to prevent the development of pharmacoresistant TLE. Lines of evidence suggest that ischemic-hypoxic lesions might occur in different brain regions, including the hippocampus, during SE. Especially in the hippocampal CA3 region, an ischemic-like lesion develops in the stratum lacunosum-moleculare and is mainly characterized by a loss of astrocytes and neuronal processes and increased immunostaining of pimonidazole which probes areas exposed to hypoxia. Interestingly, these mechanisms can contribute to neuronal cell loss and may be counteracted by drugs that can afford vascular protection, as in the case of ligands of the ghrelin receptor. Notably, some of the ghrelin receptor ligands possess a double edge effect, since they are anticonvulsant and vascular-protective, thus, potentially representing new tools to counteract the consequences of SE. This article is part of a Special Issue entitled "Status Epilepticus".
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Affiliation(s)
- Chiara Lucchi
- Department of Biomedical, Metabolic and Neural Sciences, Laboratory of Experimental Epileptology, University of Modena and Reggio Emilia, Modena, Italy
| | - Jonathan Vinet
- Department of Biomedical, Metabolic and Neural Sciences, Laboratory of Experimental Epileptology, University of Modena and Reggio Emilia, Modena, Italy
| | - Stefano Meletti
- Department of Biomedical, Metabolic and Neural Sciences, Neurology Unit, University of Modena and Reggio Emilia, Modena, Italy
| | - Giuseppe Biagini
- Department of Biomedical, Metabolic and Neural Sciences, Laboratory of Experimental Epileptology, University of Modena and Reggio Emilia, Modena, Italy; Department of Neurosciences, NOCSAE Hospital, AUSL Modena, Modena, Italy.
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Curia G, Lucchi C, Vinet J, Gualtieri F, Marinelli C, Torsello A, Costantino L, Biagini G. Pathophysiogenesis of mesial temporal lobe epilepsy: is prevention of damage antiepileptogenic? Curr Med Chem 2014; 21:663-88. [PMID: 24251566 PMCID: PMC4101766 DOI: 10.2174/0929867320666131119152201] [Citation(s) in RCA: 152] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 07/04/2013] [Accepted: 08/29/2013] [Indexed: 12/26/2022]
Abstract
Temporal lobe epilepsy (TLE) is frequently associated with hippocampal sclerosis, possibly caused by a primary brain injury that occurred a long time before the appearance of neurological symptoms. This type of epilepsy is characterized by refractoriness to drug treatment, so to require surgical resection of mesial temporal regions involved in seizure onset. Even this last therapeutic approach may fail in giving relief to patients. Although prevention of hippocampal damage and epileptogenesis after a primary event could be a key innovative approach to TLE, the lack of clear data on the pathophysiological mechanisms leading to TLE does not allow any rational therapy. Here we address the current knowledge on mechanisms supposed to be involved in epileptogenesis, as well as on the possible innovative treatments that may lead to a preventive approach. Besides loss of principal neurons and of specific interneurons, network rearrangement caused by axonal sprouting and neurogenesis are well known phenomena that are integrated by changes in receptor and channel functioning and modifications in other cellular components. In particular, a growing body of evidence from the study of animal models suggests that disruption of vascular and astrocytic components of the blood-brain barrier takes place in injured brain regions such as the hippocampus and piriform cortex. These events may be counteracted by drugs able to prevent damage to the vascular component, as in the case of the growth hormone secretagogue ghrelin and its analogues. A thoroughly investigation on these new pharmacological tools may lead to design effective preventive therapies.
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Affiliation(s)
| | | | | | | | | | | | | | - G Biagini
- Dipartimento di Scienze Biomediche, Metaboliche e Neuroscienze, Laboratorio di Epilettologia Sperimentale, Universita di Modena e Reggio Emilia, Via Campi, 287, 41125 Modena, Italy.
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Patil AA, Andrews R. Long term follow-up after multiple hippocampal transection (MHT). Seizure 2013; 22:731-4. [DOI: 10.1016/j.seizure.2013.05.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 05/17/2013] [Accepted: 05/22/2013] [Indexed: 12/14/2022] Open
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Biagini G, D'Antuono M, Benini R, de Guzman P, Longo D, Avoli M. Perirhinal cortex and temporal lobe epilepsy. Front Cell Neurosci 2013; 7:130. [PMID: 24009554 PMCID: PMC3756799 DOI: 10.3389/fncel.2013.00130] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 08/01/2013] [Indexed: 12/30/2022] Open
Abstract
The perirhinal cortex—which is interconnected with several limbic structures and is intimately involved in learning and memory—plays major roles in pathological processes such as the kindling phenomenon of epileptogenesis and the spread of limbic seizures. Both features may be relevant to the pathophysiology of mesial temporal lobe epilepsy that represents the most refractory adult form of epilepsy with up to 30% of patients not achieving adequate seizure control. Compared to other limbic structures such as the hippocampus or the entorhinal cortex, the perirhinal area remains understudied and, in particular, detailed information on its dysfunctional characteristics remains scarce; this lack of information may be due to the fact that the perirhinal cortex is not grossly damaged in mesial temporal lobe epilepsy and in models mimicking this epileptic disorder. However, we have recently identified in pilocarpine-treated epileptic rats the presence of selective losses of interneuron subtypes along with increased synaptic excitability. In this review we: (i) highlight the fundamental electrophysiological properties of perirhinal cortex neurons; (ii) briefly stress the mechanisms underlying epileptiform synchronization in perirhinal cortex networks following epileptogenic pharmacological manipulations; and (iii) focus on the changes in neuronal excitability and cytoarchitecture of the perirhinal cortex occurring in the pilocarpine model of mesial temporal lobe epilepsy. Overall, these data indicate that perirhinal cortex networks are hyperexcitable in an animal model of temporal lobe epilepsy, and that this condition is associated with a selective cellular damage that is characterized by an age-dependent sensitivity of interneurons to precipitating injuries, such as status epilepticus.
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Affiliation(s)
- Giuseppe Biagini
- Laboratory of Experimental Epileptology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia Modena, Italy
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22
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Lucchi C, Curia G, Vinet J, Gualtieri F, Bresciani E, Locatelli V, Torsello A, Biagini G. Protective but not anticonvulsant effects of ghrelin and JMV-1843 in the pilocarpine model of Status epilepticus. PLoS One 2013; 8:e72716. [PMID: 24015271 PMCID: PMC3755992 DOI: 10.1371/journal.pone.0072716] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 07/15/2013] [Indexed: 12/25/2022] Open
Abstract
In models of status epilepticus ghrelin displays neuroprotective effects mediated by the growth hormone secretagogue-receptor 1a (GHS-R1a). This activity may be explained by anticonvulsant properties that, however, are controversial. We further investigated neuroprotection and the effects on seizures by comparing ghrelin with a more effective GHS-R1a agonist, JMV-1843. Rats were treated either with ghrelin, JMV-1843 or saline 10 min before pilocarpine, which was used to induce status epilepticus. Status epilepticus, developed in all rats, was attenuated by diazepam. No differences were observed among the various groups in the characteristics of pilocarpine-induced seizures. In saline group the area of lesion, characterized by lack of glial fibrillary acidic protein immunoreactivity, was of 0.45±0.07 mm2 in the hippocampal stratum lacunosum-moleculare, and was accompanied by upregulation of laminin immunostaining, and by increased endothelin-1 expression. Both ghrelin (P<0.05) and JMV-1843 (P<0.01) were able to reduce the area of loss in glial fibrillary acidic protein immunostaining. In addition, JMV-1843 counteracted (P<0.05) the changes in laminin and endothelin-1 expression, both increased in ghrelin-treated rats. JMV-1843 was able to ameliorate neuronal survival in the hilus of dentate gyrus and medial entorhinal cortex layer III (P<0.05 vs saline and ghrelin groups). These results demonstrate diverse protective effects of growth hormone secretagogues in rats exposed to status epilepticus.
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Affiliation(s)
- Chiara Lucchi
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Giulia Curia
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Jonathan Vinet
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Fabio Gualtieri
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Elena Bresciani
- Department of Health Sciences, University of Milano-Bicocca, Monza, Italy
| | - Vittorio Locatelli
- Department of Health Sciences, University of Milano-Bicocca, Monza, Italy
| | - Antonio Torsello
- Department of Health Sciences, University of Milano-Bicocca, Monza, Italy
| | - Giuseppe Biagini
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
- Department of Neurosciences, NOCSAE Hospital, Modena, Italy
- * E-mail:
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Fan H, Guo Y, Liang X, Yuan Y, Qi X, Wang M, Ma J, Zhou H. Hydrogen sulfide protects against amyloid beta-peptide induced neuronal injury via attenuating inflammatory responses in a rat model. J Biomed Res 2013; 27:296-304. [PMID: 23885269 PMCID: PMC3721038 DOI: 10.7555/jbr.27.20120100] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 10/25/2012] [Accepted: 04/24/2013] [Indexed: 11/18/2022] Open
Abstract
Neuroinflammation has been recognized to play a critical role in the pathogenesis of Alzheimer's disease (AD), which is pathologically characterized by the accumulation of senile plaques containing activated microglia and amyloid β-peptides (Aβ). In the present study, we examined the neuroprotective effects of hydrogen sulfide (H2S) on neuroinflammation in rats with Aβ1-40 hippocampal injection. We found that Aβ-induced rats exhibited a disorder of pyramidal cell layer arrangement, and a decrease of mean pyramidal cell number in the CA1 hippocampal region compared with those in sham operated rats. NaHS (a donor of H2S, 5.6 mg/kg/d, i.p.) treatment for 3 weeks rescued neuronal cell death significantly. Moreover, we found that H2S dramatically suppressed the release of TNF-α, IL-1β and IL-6 in the hippocampus. Consistently, both immunohistochemistry and Western blotting assays showed that H2S inhibited the upregulation of COX-2 and the activation of NF-κB in the hippocampus. In conclusion, our data indicate that H2S suppresses neuroinflammation via inhibition of the NF-κB activation pathway in the Aβ-induced rat model and has potential value for AD therapy.
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Affiliation(s)
- Hao Fan
- Laboratory Center for Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu 210029, China
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Curia G, Gualtieri F, Bartolomeo R, Vezzali R, Biagini G. Resilience to audiogenic seizures is associated with p-ERK1/2 dephosphorylation in the subiculum of Fmr1 knockout mice. Front Cell Neurosci 2013; 7:46. [PMID: 23630463 PMCID: PMC3635025 DOI: 10.3389/fncel.2013.00046] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 04/03/2013] [Indexed: 12/30/2022] Open
Abstract
Young, but not adult, fragile X mental retardation gene (Fmr1) knockout (KO) mice display audiogenic seizures (AGS) that can be prevented by inhibiting extracellular signal-regulated kinases 1/2 (ERK1/2) phosphorylation. In order to identify the cerebral regions involved in these phenomena, we characterized the response to AGS in Fmr1 KO mice and wild type (WT) controls at postnatal day (P) 45 and P90. To characterize the diverse response to AGS in various cerebral regions, we evaluated the activity markers FosB/ΔFosB and phosphorylated ERK1/2 (p-ERK1/2). Wild running (100% of tested mice) followed by clonic/tonic seizures (30%) were observed in P45 Fmr1 KO mice, but not in WT mice. In P90 Fmr1 KO mice, wild running was only present in 25% of tested animals. Basal FosB/ΔFosB immunoreactivity was higher (P < 0.01 vs. WT) in the CA1 and subiculum of P45 Fmr1 KO mice. Following the AGS test, FosB/ΔFosB expression consistently increased in most of the analyzed regions in both groups at P45, but not at P90. Interestingly, FosB/ΔFosB immunoreactivity was significantly higher in P45 Fmr1 KO mice in the medial geniculate body (P < 0.05 vs. WT) and CA3 (P < 0.01). Neurons presenting with immunopositivity to p-ERK1/2 were more abundant in the subiculum of Fmr1 KO mice in control condition (P < 0.05 vs. WT, in both age groups). In this region, p-ERK1/2-immunopositive cells significantly decreased (–75%, P < 0.01) in P90 Fmr1 KO mice exposed to the AGS test, but no changes were found in P45 mice or in other brain regions. In both age groups of WT mice, p-ERK1/2-immunopositive cells increased in the subiculum after exposure to the acoustic test. Our findings illustrate that FosB/ΔFosB markers are overexpressed in the medial geniculate body and CA3 in Fmr1 KO mice experiencing AGS, and that p-ERK1/2 is markedly decreased in the subiculum of Fmr1 KO mice resistant to AGS induction. These findings suggest that resilience to AGS is associated with dephosphorylation of p-ERK1/2 in the subiculum of mature Fmr1 KO mice.
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Affiliation(s)
- Giulia Curia
- Laboratory of Experimental Epileptology, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia Modena, Italy
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Gualtieri F, Marinelli C, Longo D, Pugnaghi M, Nichelli PF, Meletti S, Biagini G. Hypoxia markers are expressed in interneurons exposed to recurrent seizures. Neuromolecular Med 2013; 15:133-46. [PMID: 23073716 DOI: 10.1007/s12017-012-8203-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 10/05/2012] [Indexed: 10/27/2022]
Abstract
An early but transient decrease in oxygen availability occurs during experimentally induced seizures. Using pimonidazole, which probes hypoxic insults, we found that by increasing the duration of pilocarpine-induced status epilepticus (SE) from 30 to 120 min, counts of pimonidazole-immunoreactive neurons also increased (P < 0.01, 120 vs 60 and 30 min). All the animals exposed to SE were immunopositive to pimonidazole, but a different scenario emerged during epileptogenesis when a decrease in pimonidazole-immunostained cells occurred from 7 to 14 days, so that only 1 out of 4 rats presented with pimonidazole-immunopositive cells. Pimonidazole-immunoreactive cells robustly reappeared at 21 days post-SE induction when all animals (7 out of 7) had developed spontaneous recurrent seizures. Specific neuronal markers revealed that immunopositivity to pimonidazole was present in cells identified by neuropeptide Y (NPY) or somatostatin antibodies. At variance, neurons immunopositive to parvalbumin or cholecystokinin were not immunopositive to pimonidazole. Pimonidazole-immunopositive neurons expressed remarkable immunoreactivity to hypoxia-inducible factor 1α (HIF-1α). Interestingly, surgical samples obtained from pharmacoresistant patients showed neurons co-labeled by HIF-1α and NPY antibodies. These interneurons, along with parvalbumin-positive interneurons that were negative to HIF-1α, showed immunopositivity to markers of cell damage, such as high-mobility group box 1 in the cytoplasm and cleaved caspase-3 in the nucleus. These findings suggest that interneurons are continuously endangered in rodent and human epileptogenic tissue. The presence of hypoxia and cell damage markers in NPY interneurons of rats and patients presenting with recurrent seizures indicates a mechanism of selective vulnerability in a specific neuronal subpopulation.
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McCloskey DP, Scharfman HE. Progressive, potassium-sensitive epileptiform activity in hippocampal area CA3 of pilocarpine-treated rats with recurrent seizures. Epilepsy Res 2011; 97:92-102. [PMID: 21880468 DOI: 10.1016/j.eplepsyres.2011.07.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Revised: 07/12/2011] [Accepted: 07/24/2011] [Indexed: 11/28/2022]
Abstract
Rat hippocampal area CA3 pyramidal cells synchronously discharge in rhythmic bursts of action potentials after acute disinhibition or convulsant treatment in vitro. These burst discharges resemble epileptiform activity, and are of interest because they may shed light on mechanisms underlying limbic seizures. However, few studies have examined CA3 burst discharges in an animal model of epilepsy, because a period of prolonged, severe seizures (status epilepticus) is often used to induce the epileptic state, which can lead to extensive neuronal loss in CA3. Therefore, the severity of pilocarpine-induced status epilepticus was decreased with anticonvulsant treatment to reduce damage. Rhythmic burst discharges were recorded in the majority of slices from these animals, between two weeks and nine months after status epilepticus. The incidence and amplitude of bursts progressively increased with time after status, even after spontaneous behavioral seizures had begun. The results suggest that modifying the pilocarpine models of temporal lobe epilepsy to reduce neuronal loss leads to robust network synchronization in area CA3. The finding that these bursts increase long after spontaneous behavioral seizures begin supports previous arguments that temporal lobe epilepsy exhibits progressive pathophysiology.
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Affiliation(s)
- Daniel P McCloskey
- Department of Psychology and Program in Developmental Neuroscience, College of Staten Island, City University of New York, Staten Island, New York 10314, United States.
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Lévesque M, Bortel A, Gotman J, Avoli M. High-frequency (80-500 Hz) oscillations and epileptogenesis in temporal lobe epilepsy. Neurobiol Dis 2011; 42:231-41. [PMID: 21238589 PMCID: PMC4873283 DOI: 10.1016/j.nbd.2011.01.007] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 11/17/2010] [Accepted: 01/02/2011] [Indexed: 11/25/2022] Open
Abstract
High-frequency oscillations (HFOs), termed ripples (80-200 Hz) and fast ripples (250-600 Hz), are recorded in the EEG of epileptic patients and in animal epilepsy models; HFOs are thought to reflect pathological activity and seizure onset zones. Here, we analyzed the temporal and spatial evolution of interictal spikes with and without HFOs in the rat pilocarpine model of temporal lobe epilepsy. Depth electrode recordings from dentate gyrus (DG), CA3 region, subiculum and entorhinal cortex (EC), were obtained from rats between the 4th and 15th day after a status epilepticus (SE) induced by i.p. injection of pilocarpine. The first seizure occurred 6.1 ± 2.5 days after SE (n = 7 rats). Five of 7 animals exhibited interictal spikes that co-occurred with fast ripples accounting for 4.9 ± 4.6% of all analyzed interictal spikes (n = 12,886) while all rats showed interictal spikes co-occurring with ripples, accounting for 14.3 ± 3.4% of all events. Increased rates of interictal spikes without HFOs in the EC predicted upcoming seizures on the following day, while rates of interictal spikes with fast ripples in CA3 reflected periods of high seizure occurrence. Finally, interictal spikes co-occurring with ripples did not show any specific relation to seizure occurrence. Our findings identify different temporal and spatial developmental patterns for the rates of interictal spikes with or without HFOs in relation with seizure occurrence. These distinct categories of interictal spikes point at dynamic processes that should bring neuronal networks close to seizure generation.
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Affiliation(s)
- Maxime Lévesque
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montreal, Qc, Canada H3A 2B4
| | - Aleksandra Bortel
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montreal, Qc, Canada H3A 2B4
| | - Jean Gotman
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montreal, Qc, Canada H3A 2B4
| | - Massimo Avoli
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montreal, Qc, Canada H3A 2B4
- Dipartimento di Medicina Sperimentale, Sapienza Università di Roma, Viale del Castro Laurenziano 9, 00185 Roma, Italy
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Abstract
Activation of the axons of the granule cells, the mossy fibers, excites pyramidal cells and interneurons in the CA3 area, which, in turn, inhibit pyramidal cells. The integration of the various inputs that converge onto CA3 cells has been studied by pharmacological dissection of either the excitatory or inhibitory components. This strategy has the disadvantage of partially isolating the recorded cell from the network, ignoring the sources and the impact of concurrent inputs. To overcome this limitation, we dissociated excitatory and inhibitory synaptic conductances by mathematical extraction techniques, and analysed the dynamics of the integration of excitatory and inhibitory inputs in pyramidal cells and stratum lucidum interneurons (Sl-Ints) of CA3. We have uncovered a shunting mechanism that decreases the responsiveness of CA3 output cells to mossy fiber input after a period of enhanced excitability. The activation of the dentate gyrus (DG) after applying a kindling-like protocol in vitro, or after producing one or several seizures in vivo, results in a graded and reversible increase of inhibitory conductances in pyramidal cells, while in Sl-Ints, an increase of excitatory conductances occurs. Thus, interneurons reach more depolarized membrane potentials on DG activation yielding a high excitatory postsynaptic potential-spike coupling, while the contrary occurs in pyramidal cells. This effective activation of feedforward inhibition is synergized by the emergence of direct DG-mediated inhibition on pyramidal cells. These factors force the synaptic conductance to peak at a potential value close to resting membrane potential, thus producing shunt inhibition and decreasing the responsiveness of CA3 output cells to mossy fiber input.
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Affiliation(s)
- Mario Treviño
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional Apartado Postal 14-740, México D.F. 07000, Mexico
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Abstract
Interictal spiking is seen in the EEG of epileptic patients between seizures. To date, the roles played by interictal events in seizure occurrence and in epileptogenesis remain elusive. While interictal spikes may herald the onset of electrographic seizures, experimental data indicate that hippocampus-driven interictal events prevent seizure precipitation. Even less clear than the role of interictal events in seizure occurrence is whether and how interictal spikes contribute to epileptogenesis. Thus, while plastic changes within limbic neuronal networks may result from ongoing interictal activity, experimental evidence supports the view that epileptogenesis is accompanied by a decrease in hippocampus-driven interictal activity.
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Affiliation(s)
- Massimo Avoli
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, Montréal, Canada
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Abstract
Massive and Specific Dysregulation of Direct Cortical Input to the Hippocampus in Temporal Lobe Epilepsy. Ang CW, Carlson GC, Coulter DA. J Neurosci 2006;26(46):11850–11856. Epilepsy affects 1–2% of the population, with temporal lobe epilepsy (TLE) the most common variant in adults. Clinical and experimental studies have demonstrated hippocampal involvement in the seizures underlying TLE. However, identification of specific functional deficits in hippocampal circuits associated with possible roles in seizure generation remains controversial. Significant attention has focused on anatomic and cellular alterations in the dentate gyrus. The dentate gyrus is a primary gateway regulating cortical input to the hippocampus and, thus, a possible contributor to the aberrant cortical-hippocampal interactions underlying the seizures of TLE. Alternate cortical pathways innervating the hippocampus might also contribute to seizure initiation. Despite this potential importance in TLE, these pathways have received little study. Using simultaneous voltage-sensitive dye imaging and patch-clamp recordings in slices from animals with epilepsy, we assessed the relative degree of synaptic excitation activated by multiple cortical inputs to the hippocampus. Surprisingly, dentate gyrus-mediated regulation of the relay of cortical input to the hippocampus is unchanged in epileptic animals, and input via the Schaffer collaterals is actually decreased despite reduction in Schaffer-evoked inhibition. In contrast, a normally weak direct cortical input to area CA1 of hippocampus, the temporoammonic pathway, exhibits a TLE-associated transformation from a spatially restricted, highly regulated pathway to an excitatory projection with >10-fold increased effectiveness. This dysregulated temporoammonic pathway is critically positioned to mediate generation and/or propagation of seizure activity in the hippocampus.
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Bortel A, Longo D, de Guzman P, Dubeau F, Biagini G, Avoli M. Selective changes in inhibition as determinants for limited hyperexcitability in the insular cortex of epileptic rats. Eur J Neurosci 2010; 31:2014-23. [PMID: 20497472 DOI: 10.1111/j.1460-9568.2010.07225.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The insular cortex (IC) is involved in the generalization of epileptic discharges in temporal lobe epilepsy (TLE), whereas seizures originating in the IC can mimic the epileptic phenotype seen in some patients with TLE. However, few studies have addressed the changes occurring in the IC in TLE animal models. Here, we analyzed the immunohistochemical and electrophysiological properties of IC networks in non-epileptic control and pilocarpine-treated epileptic rats. Neurons identified with a neuron-specific nuclear protein antibody showed similar counts in the two types of tissue but parvalbumin- and neuropeptide Y-positive interneurons were significantly decreased (parvalbumin, approximately -35%; neuropeptide Y, approximately -38%; P < 0.01) in the epileptic IC. Non-adapting neurons were seen more frequently in the epileptic IC during intracellular injection of depolarizing current pulses. In addition, single-shock electrical stimuli elicited network-driven epileptiform responses in 87% of epileptic and 22% of non-epileptic control neurons (P < 0.01) but spontaneous postsynaptic potentials had similar amplitude, duration and intervals of occurrence in the two groups. Finally, pharmacologically isolated, GABA(A) receptor-mediated inhibitory postsynaptic potentials had more negative reversal potential (P < 0.01) and higher peak conductance (P < 0.05) in epileptic tissue. These data reveal moderate increased network excitability in the IC of pilocarpine-treated epileptic rats. We propose that this limited degree of hyperexcitability originates from the loss of parvalbumin- and neuropeptide Y-positive interneurons that is compensated by an increased drive for GABA(A) receptor-mediated inhibition.
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Affiliation(s)
- Aleksandra Bortel
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University, Room 794, Montreal, QC, H3A 2B4, Canada
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Panuccio G, D'Antuono M, de Guzman P, De Lannoy L, Biagini G, Avoli M. In vitro ictogenesis and parahippocampal networks in a rodent model of temporal lobe epilepsy. Neurobiol Dis 2010; 39:372-80. [PMID: 20452424 DOI: 10.1016/j.nbd.2010.05.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Revised: 04/14/2010] [Accepted: 05/01/2010] [Indexed: 12/29/2022] Open
Abstract
Temporal lobe epilepsy (TLE) is a chronic epileptic disorder involving the hippocampal formation. Details on the interactions between the hippocampus proper and parahippocampal networks during ictogenesis remain, however, unclear. In addition, recent findings have shown that epileptic limbic networks maintained in vitro are paradoxically less responsive than non-epileptic control (NEC) tissue to application of the convulsant drug 4-aminopyridine (4AP). Field potential recordings allowed us to establish here the effects of 4AP in brain slices obtained from NEC and pilocarpine-treated epileptic rats; these slices included the hippocampus and parahippocampal areas such as entorhinal and perirhinal cortices and the amygdala. First, we found that both types of tissue generate epileptiform discharges with similar electrographic characteristics. Further investigation showed that generation of robust ictal-like discharges in the epileptic rat tissue is (i) favored by decreased hippocampal output (ii) reinforced by EC-subiculum interactions and (iii) predominantly driven by amygdala networks. We propose that a functional switch to alternative synaptic routes may promote network hyperexcitability in the epileptic limbic system.
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Affiliation(s)
- G Panuccio
- Montreal Neurological Institute and Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
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Benini R, Longo D, Biagini G, Avoli M. Perirhinal cortex hyperexcitability in pilocarpine-treated epileptic rats. Hippocampus 2010; 21:702-13. [PMID: 20865722 DOI: 10.1002/hipo.20785] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/22/2010] [Indexed: 11/09/2022]
Abstract
The perirhinal cortex (PC), which is heavily connected with several epileptogenic regions of the limbic system such as the entorhinal cortex and amygdala, is involved in the generation and spread of seizures. However, the functional alterations occurring within an epileptic PC network are unknown. Here, we analyzed this issue by using in vitro electrophysiology and immunohistochemistry in brain tissue obtained from pilocarpine-treated epileptic rats and age-matched, nonepileptic controls (NECs). Neurons recorded intracellularly from the PC deep layers in the two experimental groups had similar intrinsic and firing properties and generated spontaneous depolarizing and hyperpolarizing postsynaptic potentials with comparable duration and amplitude. However, spontaneous and stimulus-induced epileptiform discharges were seen with field potential recordings in over one-fifth of pilocarpine-treated slices but never in NEC tissue. These network events were reduced in duration by antagonizing NMDA receptors and abolished by NMDA + non-NMDA glutamatergic receptor antagonists. Pharmacologically isolated isolated inhibitory postsynaptic potentials had reversal potentials for the early GABA(A) receptor-mediated component that were significantly more depolarized in pilocarpine-treated cells. Experiments with a potassium-chloride cotransporter 2 antibody identified, in pilocarpine-treated PC, a significant immunostaining decrease that could not be explained by neuronal loss. However, interneurons expressing parvalbumin and neuropeptide Y were found to be decreased throughout the PC, whereas cholecystokinin-positive cells were diminished in superficial layers. These findings demonstrate synaptic hyperexcitability that is contributed by attenuated inhibition in the PC of pilocarpine-treated epileptic rats and underscore the role of PC networks in temporal lobe epilepsy.
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Affiliation(s)
- Ruba Benini
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, Montreal, Canada
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Baldelli E, Leo G, Andreoli N, Fuxe K, Biagini G, Agnati LF. Homocysteine Potentiates Seizures and Cell Loss Induced by Pilocarpine Treatment. Neuromolecular Med 2009; 12:248-59. [DOI: 10.1007/s12017-009-8110-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Accepted: 12/02/2009] [Indexed: 10/20/2022]
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Chaichana KL, Parker SL, Olivi A, Quiñones-Hinojosa A. Long-term seizure outcomes in adult patients undergoing primary resection of malignant brain astrocytomas. J Neurosurg 2009; 111:282-92. [DOI: 10.3171/2009.2.jns081132] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
Seizures are a common presenting symptom and cause of morbidity for patients with malignant astrocytomas. The authors set out to determine preoperative seizure characteristics, effects of surgery on seizure control, and factors associated with prolonged seizure control in patients with malignant astrocytomas.
Methods
Cases involving adult patients who underwent primary resection of a hemispheric anaplastic astrocytoma (AA) or glioblastoma multiforme (GBM) at the Johns Hopkins Medical Institutions between 1996 and 2006 were retrospectively reviewed. Multivariate logistical regression analysis was used to identify associations with pre-operative seizures, and multivariate proportional hazards regression analyses were used to identify associations with prolonged seizure control following resection.
Results
Of the 648 patients (505 with GBM, 143 with AA) in this series, 153 (24%) presented with seizures. The factors more commonly associated with preoperative seizures were AA pathology (p = 0.03), temporal lobe involvement (p = 0.04), and cortical location (p = 0.04), while the factors less commonly associated with preoperative seizures were greater age (p = 0.03) and larger tumor size (p ≤ 0.001). Among those patients with a history of seizures, outcome 12 months after surgery was Engel Class I (seizure free) in 77%, Class II (rare seizures) in 12%, Class III (meaningful improvement) in 6%, and Class IV (no improvement) in 5%. Postoperative seizures were rare in patients without a history of preoperative seizures. The factor positively associated with prolonged seizure control was increased Karnofsky Performance Scale score (p = 0.002), while the factors negatively associated with seizure control were preoperative uncontrolled seizures (p = 0.03) and parietal lobe involvement (p = 0.005). Seizure recurrence in patients with postoperative seizure control was independently associated with tumor recurrence (p = 0.006).
Conclusions
The identification and consideration of factors associated with prolonged seizure control may help guide treatment strategies aimed at improving the quality of life for patients with malignant astrocytomas.
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Stafstrom CE, Ockuly JC, Murphree L, Valley MT, Roopra A, Sutula TP. Anticonvulsant and antiepileptic actions of 2-deoxy-D-glucose in epilepsy models. Ann Neurol 2009; 65:435-47. [PMID: 19399874 DOI: 10.1002/ana.21603] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVE Conventional anticonvulsants reduce neuronal excitability through effects on ion channels and synaptic function. Anticonvulsant mechanisms of the ketogenic diet remain incompletely understood. Because carbohydrates are restricted in patients on the ketogenic diet, we evaluated the effects of limiting carbohydrate availability by reducing glycolysis using the glycolytic inhibitor 2-deoxy-D-glucose (2DG) in experimental models of seizures and epilepsy. METHODS Acute anticonvulsant actions of 2DG were assessed in vitro in rat hippocampal slices perfused with 7.5mM [K(+)](o), 4-aminopyridine, or bicuculline, and in vivo against seizures evoked by 6 Hz stimulation in mice, audiogenic stimulation in Fring's mice, and maximal electroshock and subcutaneous pentylenetetrazol (Metrazol) in rats. Chronic antiepileptic effects of 2DG were evaluated in rats kindled from olfactory bulb or perforant path. RESULTS 2DG (10mM) reduced interictal epileptiform bursts induced by 7.5mM [K(+)](o), 4-aminopyridine, and bicuculline, and electrographic seizures induced by high [K(+)](o) in CA3 of hippocampus. 2DG reduced seizures evoked by 6 Hz stimulation in mice (effective dose [ED]50 = 79.7 mg/kg) and audiogenic stimulation in Fring's mice (ED50 = 206.4 mg/kg). 2DG exerted chronic antiepileptic action by increasing afterdischarge thresholds in perforant path (but not olfactory bulb) kindling and caused a twofold slowing in progression of kindled seizures at both stimulation sites. 2DG did not protect against maximal electroshock or Metrazol seizures. INTERPRETATION The glycolytic inhibitor 2DG exerts acute anticonvulsant and chronic antiepileptic actions, and has a novel pattern of effectiveness in preclinical screening models. These results identify metabolic regulation as a potential therapeutic target for seizure suppression and modification of epileptogenesis.
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Affiliation(s)
- Carl E Stafstrom
- Department of Neurology, University of Wisconsin, Madison, WI 53792, USA.
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Biagini G, Baldelli E, Longo D, Contri MB, Guerrini U, Sironi L, Gelosa P, Zini I, Ragsdale DS, Avoli M. Proepileptic influence of a focal vascular lesion affecting entorhinal cortex-CA3 connections after status epilepticus. J Neuropathol Exp Neurol 2008; 67:687-701. [PMID: 18596544 DOI: 10.1097/NEN.0b013e318181b8ae] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
In limbic seizures, neuronal excitation is conveyed from the entorhinal cortex directly to CA1 and subicular regions. This phenomenon is associated with a reduced ability of CA3 to respond to entorhinal cortex inputs. Here, we describe a lesion that destroys the perforant path in CA3 after status epilepticus (SE) induced by pilocarpine injection in 8-week-old rats. Using magnetic resonance imaging, immunohistochemical, and ultrastructural analyses, we determined that this lesion develops after 30 minutes of SE and is characterized by microhemorrhages and ischemia. After a longer period of SE, the lesion invariably involves the upper blade of the dentate gyrus. Adult rats treated with subcutaneous diazepam (20 mg kg for 3 days) did not develop the dentate gyrus lesion and had less frequent spontaneous recurrent seizures (p < 0.01). Young (3-week-old) rats rarely (20%) developed the CA3 lesion, and their spontaneous seizures were delayed (p < 0.01). To investigate the role of the damaged CA3 in seizure activity, we reinduced SE in adult and young epileptic rats. Using FosB/DeltaFosB markers, we found induction of FosB/DeltaFosB immunopositivity in CA3 neurons of young but not in adult rats. These experiments indicate that SE can produce a focal lesion in the perforant path that may affect the roles of the hippocampus in epileptic rats.
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Curia G, Longo D, Biagini G, Jones RS, Avoli M. The pilocarpine model of temporal lobe epilepsy. J Neurosci Methods 2008; 172:143-57. [PMID: 18550176 PMCID: PMC2518220 DOI: 10.1016/j.jneumeth.2008.04.019] [Citation(s) in RCA: 729] [Impact Index Per Article: 45.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Revised: 04/17/2008] [Accepted: 04/18/2008] [Indexed: 01/17/2023]
Abstract
Understanding the pathophysiogenesis of temporal lobe epilepsy (TLE) largely rests on the use of models of status epilepticus (SE), as in the case of the pilocarpine model. The main features of TLE are: (i) epileptic foci in the limbic system; (ii) an “initial precipitating injury”; (iii) the so-called “latent period”; and (iv) the presence of hippocampal sclerosis leading to reorganization of neuronal networks. Many of these characteristics can be reproduced in rodents by systemic injection of pilocarpine; in this animal model, SE is followed by a latent period and later by the appearance of spontaneous recurrent seizures (SRSs). These processes are, however, influenced by experimental conditions such as rodent species, strain, gender, age, doses and routes of pilocarpine administration, as well as combinations with other drugs administered before and/or after SE. In the attempt to limit these sources of variability, we evaluated the methodological procedures used by several investigators in the pilocarpine model; in particular, we have focused on the behavioural, electrophysiological and histopathological findings obtained with different protocols. We addressed the various experimental approaches published to date, by comparing mortality rates, onset of SRSs, neuronal damage, and network reorganization. Based on the evidence reviewed here, we propose that the pilocarpine model can be a valuable tool to investigate the mechanisms involved in TLE, and even more so when standardized to reduce mortality at the time of pilocarpine injection, differences in latent period duration, variability in the lesion extent, and SRS frequency.
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Affiliation(s)
- Giulia Curia
- Montreal Neurological Institute and Departments of Neurology & Neurosurgery and Physiology, McGill University, Montreal, QC, Canada H3A 2B4
| | - Daniela Longo
- Dipartimento di Scienze Biomediche, Università di Modena e Reggio Emilia, 41100 Modena, Italy
| | - Giuseppe Biagini
- Dipartimento di Scienze Biomediche, Università di Modena e Reggio Emilia, 41100 Modena, Italy
| | - Roland S.G. Jones
- Department of Pharmacy and Pharmacology, University of Bath, Bath BA2 7AY, United Kingdom
| | - Massimo Avoli
- Montreal Neurological Institute and Departments of Neurology & Neurosurgery and Physiology, McGill University, Montreal, QC, Canada H3A 2B4
- Dipartimento di Medicina Sperimentale, Università di Roma “La Sapienza”, 00185 Roma, Italy
- Corresponding author at: 3801 University, Room 794, Montreal, QC, Canada H3A 2B4. Tel.: +1 514 398 1955; fax: +1 514 398 8106.
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de Guzman P, Inaba Y, Baldelli E, de Curtis M, Biagini G, Avoli M. Network hyperexcitability within the deep layers of the pilocarpine-treated rat entorhinal cortex. J Physiol 2008; 586:1867-83. [PMID: 18238812 DOI: 10.1113/jphysiol.2007.146159] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
In this study we report that in the presence of normal buffer, epileptiform discharges occur spontaneously (duration = 2.60 +/- 0.49 s) or can be induced by electrical stimuli (duration = 2.50 +/- 0.62 s) in the entorhinal cortex (EC) of brain slices obtained from pilocarpine-treated rats but not in those from age-matched, nonepileptic control (NEC) animals. These network-driven epileptiform events consist of field oscillatory sequences at frequencies greater than 200 Hz that most often initiate in the lateral EC and propagate to the medial EC with 4-63 ms delays. The NMDA receptor antagonist CPP depresses the rate of occurrence (P < 0.01) of these spontaneous epileptiform discharges but fails in blocking them. Paradoxically, stimulus-induced epileptiform responses are enhanced in duration during CPP application. However, concomitant application of NMDA and non-NMDA glutamatergic antagonists abolishes spontaneous and stimulus-induced epileptiform events. Intracellular recordings from lateral EC layer V cells indicate a lower frequency of spontaneous hyperpolarizing postsynaptic potentials in pilocarpine-treated tissue than in NEC (P < 0.002) both under control conditions and with glutamatergic receptor blockade; the reversal potential of pharmacologically isolated GABA(A) receptor-mediated inhibitory postsynaptic potentials has similar values in the two types of tissue. Finally, immunohistochemical analysis shows that parvalbumin-positive interneurons are selectively reduced in number in EC deep layers. Collectively, these results indicate that reduced inhibition within the pilocarpine-treated EC layer V may promote network epileptic hyperexcitability.
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Affiliation(s)
- Philip de Guzman
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, Montreal, QC H3A 2B4, Canada
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Abstract
The hippocampal commissural system has recently been found to participate in the generation of mirror foci after kainate-induced epileptiform discharges. In the present study we have evaluated the electrophysiological alterations in the ventral commissural hippocampal system that originates in the pyramidal CA3 cells and connects to the contralateral CA3 pyramidal cells. The recordings were performed in epileptic rats 24 h after an early behavioural spontaneous seizure between 5 and 21 days after pilocarpine-induced status epilepticus. Epileptic animals presented a marked increase in neuronal excitability after contralateral CA3 stimulation, characterized by a shift to the left in the input-output curve and the clear appearance of a population spike. Input-output curves showed that maximum population excitatory postsynaptic potential (pEPSP) amplitude was decreased by 30%, which could be related to cell death in these regions. Using paired-pulse protocols to evaluate a fast form of synaptic plasticity (i.e. paired-pulse facilitation) we observed that, despite the similar pEPSP amplitude between control and experimental groups, only epileptic animals showed strong paired-pulse population spike facilitation up to 500 ms interstimulus intervals. Despite increased excitability and pyramidal cell death, epileptic animals presented a more robust potentiation after high-frequency stimulation than controls, a protocol used to evaluate a slow form of synaptic plasticity (i.e. long-term potentiation). The increased excitability in CA3 pyramidal neurons enhanced the probability of burst activity in these neurons; this could lead to greater CA1 synchronization. The present results might have relevance for the understanding of epileptogenesis and of learning and memory deficits seen in temporal lobe epilepsy.
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Affiliation(s)
- Claudio M T Queiroz
- Department of Physiology, UNIFESP-EPM, Rua Botucatu, 862-04023-062, São Paulo, SP, Brazil
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Treviño M, Vivar C, Gutiérrez R. Beta/gamma oscillatory activity in the CA3 hippocampal area is depressed by aberrant GABAergic transmission from the dentate gyrus after seizures. J Neurosci 2007; 27:251-9. [PMID: 17202493 PMCID: PMC6672272 DOI: 10.1523/jneurosci.3815-06.2007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Oscillatory activity in the CA3 region is thought to be involved in the encoding and retrieval of information. These oscillations originate from the recurrent excitation between pyramidal cells that are entrained by the synchronous rhythmic inhibition of local interneurons. We show here that, after seizures, the dentate gyrus (DG) tonically inhibits beta/gamma (20-24 Hz) field oscillations in the CA3 area through GABA-mediated signaling. These oscillations originate in the interneuron network because they are maintained in the presence of ionotropic glutamate receptor antagonists, and they can be blocked by GABA(A) receptor antagonists or by perfusion of a calcium-free extracellular medium. Inhibition of this oscillatory activity requires intact DG-to-CA3 connections, and it is suppressed by the activation of metabotropic glutamate receptors (mGluR). The influence of mGluR activation was reflected in the spontaneous subthreshold membrane oscillations of CA3 interneurons after one seizure but could also be observed in pyramidal cells after several seizures. Coincident stimulation of the DG at and beta/gamma frequencies produced a frequency-dependent excitation of interneurons and the inhibition of pyramidal cells. Indeed, these effects were maximal at the frequency that matched the mGluR-sensitive spontaneous field oscillations, suggesting a resonance phenomenon. Our results shed light on the mechanisms that may underlie the deficits in memory and cognition observed after epileptic seizures.
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Affiliation(s)
- Mario Treviño
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados, México DF 07000, México
| | - Carmen Vivar
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados, México DF 07000, México
| | - Rafael Gutiérrez
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados, México DF 07000, México
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Biagini G, Baldelli E, Longo D, Pradelli L, Zini I, Rogawski MA, Avoli M. Endogenous neurosteroids modulate epileptogenesis in a model of temporal lobe epilepsy. Exp Neurol 2006; 201:519-24. [PMID: 16780839 DOI: 10.1016/j.expneurol.2006.04.029] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2006] [Revised: 03/28/2006] [Accepted: 04/21/2006] [Indexed: 10/24/2022]
Abstract
Neurosteroids modulate seizure susceptibility, but their role in the regulation of epileptogenesis is unknown. Status epilepticus (SE) induces temporal lobe epileptogenesis following a latent period in which glial cells are activated. Here, we found that P450scc, the rate-limiting enzyme in steroid synthesis, is upregulated in hippocampal glia during the latent period after pilocarpine-induced SE in rats. More prolonged SE was associated with greater P450scc expression and longer latencies to the development of seizures, suggesting that enhanced steroid synthesis retards epileptogenesis. The 5alpha-reductase inhibitor finasteride, which blocks neurosteroid synthesis, reduced the latent period, indicating that glia-derived neurosteroids may be antiepileptogenic.
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Affiliation(s)
- Giuseppe Biagini
- Dipartimento di Scienze Biomediche, Università di Modena e Reggio Emilia, Modena, Italy.
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de Guzman P, Inaba Y, Biagini G, Baldelli E, Mollinari C, Merlo D, Avoli M. Subiculum network excitability is increased in a rodent model of temporal lobe epilepsy. Hippocampus 2006; 16:843-60. [PMID: 16897722 DOI: 10.1002/hipo.20215] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In this study, we used in vitro electrophysiology along with immunohistochemistry and molecular techniques to study the subiculum--a limbic structure that gates the information flow from and to the hippocampus--in pilocarpine-treated epileptic rats. Comparative data were obtained from age-matched nonepileptic controls (NEC). Subicular neurons in hippocampal-entorhinal cortex (EC) slices of epileptic rats were: (i) hyperexcitable when activated by CA1 or EC inputs; and (ii) generated spontaneous postsynaptic potentials at higher frequencies than NEC cells. Analysis of pharmacologically isolated, GABA(A) receptor-mediated inhibitory postsynaptic potentials revealed more positive reversal potentials in epileptic tissue (-67.8 +/- 6.3 mV, n = 16 vs. -74.8 +/- 3.6 mV in NEC, n = 13; P < 0.001) combined with a reduction in peak conductance (17.6 +/- 11.3 nS vs. 41.1 +/- 26.7 nS in NEC; P < 0.003). These electrophysiological data correlated in the epileptic subiculum with (i) reduced levels of mRNA expression and immunoreactivity of the neuron-specific potassium-chloride cotransporter 2; (ii) decreased number of parvalbumin-positive cells; and (iii) increased synaptophysin (a putative marker of sprouting) immunoreactivity. These findings identify an increase in network excitability within the subiculum of pilocarpine-treated, epileptic rats and point at a reduction in inhibition as an underlying mechanism.
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Affiliation(s)
- Philip de Guzman
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
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