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Dusing MR, LaSarge CL, Drake AW, Westerkamp GC, McCoy C, Hetzer SM, Kraus KL, Pedapati EV, Danzer SC. Transient Seizure Clusters and Epileptiform Activity Following Widespread Bilateral Hippocampal Interneuron Ablation. eNeuro 2024; 11:ENEURO.0317-23.2024. [PMID: 38575351 PMCID: PMC11036118 DOI: 10.1523/eneuro.0317-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 03/28/2024] [Accepted: 03/29/2024] [Indexed: 04/06/2024] Open
Abstract
Interneuron loss is a prominent feature of temporal lobe epilepsy in both animals and humans and is hypothesized to be critical for epileptogenesis. As loss occurs concurrently with numerous other potentially proepileptogenic changes, however, the impact of interneuron loss in isolation remains unclear. For the present study, we developed an intersectional genetic approach to induce bilateral diphtheria toxin-mediated deletion of Vgat-expressing interneurons from dorsal and ventral hippocampus. In a separate group of mice, the same population was targeted for transient neuronal silencing with DREADDs. Interneuron ablation produced dramatic seizure clusters and persistent epileptiform activity. Surprisingly, after 1 week seizure activity declined precipitously and persistent epileptiform activity disappeared. Occasional seizures (≈1/day) persisted to the end of the experiment at 4 weeks. In contrast to the dramatic impact of interneuron ablation, transient silencing produced large numbers of interictal spikes, a significant but modest increase in seizure occurrence and changes in EEG frequency band power. Taken together, findings suggest that the hippocampus regains relative homeostasis-with occasional breakthrough seizures-in the face of an extensive and abrupt loss of interneurons.
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Affiliation(s)
- Mary R Dusing
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039
| | - Candi L LaSarge
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039
- Neuroscience Graduate Program, University of Cincinnati, Cincinnati, Ohio 45229-3039
| | - Austin W Drake
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039
- Neuroscience Graduate Program, University of Cincinnati, Cincinnati, Ohio 45229-3039
- Medical Scientist Training Program, University of Cincinnati College of Medicine, Cincinnati, Ohio 45229-3039
| | - Grace C Westerkamp
- Division of Child Psychiatry, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039
| | - Carlie McCoy
- Division of Neurosurgery, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039
| | - Shelby M Hetzer
- Neuroscience Graduate Program, University of Cincinnati, Cincinnati, Ohio 45229-3039
| | - Kimberly L Kraus
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039
- Neuroscience Graduate Program, University of Cincinnati, Cincinnati, Ohio 45229-3039
- Medical Scientist Training Program, University of Cincinnati College of Medicine, Cincinnati, Ohio 45229-3039
| | - Ernest V Pedapati
- Division of Child Psychiatry, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039
| | - Steve C Danzer
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039
- Neuroscience Graduate Program, University of Cincinnati, Cincinnati, Ohio 45229-3039
- Medical Scientist Training Program, University of Cincinnati College of Medicine, Cincinnati, Ohio 45229-3039
- Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45229-3039
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2
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Clasadonte J, Deprez T, Stephens GS, Mairet-Coello G, Cortin PY, Boutier M, Frey A, Chin J, Rajman M. ΔFosB is part of a homeostatic mechanism that protects the epileptic brain from further deterioration. Front Mol Neurosci 2024; 16:1324922. [PMID: 38283700 PMCID: PMC10810990 DOI: 10.3389/fnmol.2023.1324922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 12/13/2023] [Indexed: 01/30/2024] Open
Abstract
Activity induced transcription factor ΔFosB plays a key role in different CNS disorders including epilepsy, Alzheimer's disease, and addiction. Recent findings suggest that ΔFosB drives cognitive deficits in epilepsy and together with the emergence of small molecule inhibitors of ΔFosB activity makes it an interesting therapeutic target. However, whether ΔFosB contributes to pathophysiology or provides protection in drug-resistant epilepsy is still unclear. In this study, ΔFosB was specifically downregulated by delivering AAV-shRNA into the hippocampus of chronically epileptic mice using the drug-resistant pilocarpine model of mesial temporal epilepsy (mTLE). Immunohistochemistry analyses showed that prolonged downregulation of ΔFosB led to exacerbation of neuroinflammatory markers of astrogliosis and microgliosis, loss of mossy fibers, and hippocampal granule cell dispersion. Furthermore, prolonged inhibition of ΔFosB using a ΔJunD construct to block ΔFosB signaling in a mouse model of Alzheimer's disease, that exhibits spontaneous recurrent seizures, led to similar findings, with increased neuroinflammation and decreased NPY expression in mossy fibers. Together, these data suggest that seizure-induced ΔFosB, regardless of seizure-etiology, is part of a homeostatic mechanism that protects the epileptic brain from further deterioration.
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Affiliation(s)
- Jerome Clasadonte
- Epilepsy Discovery Research, UCB Biopharma SRL, Braine-l’Alleud, Belgium
| | - Tania Deprez
- Epilepsy Discovery Research, UCB Biopharma SRL, Braine-l’Alleud, Belgium
| | | | | | - Pierre-Yves Cortin
- Epilepsy Discovery Research, UCB Biopharma SRL, Braine-l’Alleud, Belgium
| | - Maxime Boutier
- Epilepsy Discovery Research, UCB Biopharma SRL, Braine-l’Alleud, Belgium
| | - Aurore Frey
- Epilepsy Discovery Research, UCB Biopharma SRL, Braine-l’Alleud, Belgium
| | - Jeannie Chin
- Baylor College of Medicine, Houston, TX, United States
| | - Marek Rajman
- Epilepsy Discovery Research, UCB Biopharma SRL, Braine-l’Alleud, Belgium
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3
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Ng XY, Wu Y, Lin Y, Yaqoob SM, Greene LE, De Camilli P, Cao M. Mutations in Parkinsonism-linked endocytic proteins synaptojanin1 and auxilin have synergistic effects on dopaminergic axonal pathology. NPJ Parkinsons Dis 2023; 9:26. [PMID: 36792618 PMCID: PMC9932162 DOI: 10.1038/s41531-023-00465-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 01/20/2023] [Indexed: 02/17/2023] Open
Abstract
Parkinson's disease (PD) is a neurodegenerative disorder characterized by defective dopaminergic (DAergic) input to the striatum. Mutations in two genes encoding synaptically enriched clathrin-uncoating factors, synaptojanin 1 (SJ1) and auxilin, have been implicated in atypical Parkinsonism. SJ1 knock-in (SJ1-KIRQ) mice carrying a disease-linked mutation display neurological manifestations reminiscent of Parkinsonism. Here we report that auxilin knockout (Aux-KO) mice display dystrophic changes of a subset of nigrostriatal DAergic terminals similar to those of SJ1-KIRQ mice. Furthermore, Aux-KO/SJ1-KIRQ double mutant mice have shorter lifespan and more severe synaptic defects than single mutant mice. These include increase in dystrophic striatal nerve terminals positive for DAergic markers and for the PD risk protein SV2C, as well as adaptive changes in striatal interneurons. The synergistic effect of the two mutations demonstrates a special lability of DAergic neurons to defects in clathrin uncoating, with implications for PD pathogenesis in at least some forms of this condition.
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Affiliation(s)
- Xin Yi Ng
- Programme in Neuroscience and Behavioural Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Yumei Wu
- Departments of Neuroscience and Cell Biology, Howard Hughes Medical Institute, Program in Cellular Neuroscience, Neurodegeneration and Repair, Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, 06510, USA
- Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD, USA
| | - Youneng Lin
- Programme in Neuroscience and Behavioural Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Sidra Mohamed Yaqoob
- Programme in Neuroscience and Behavioural Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Lois E Greene
- Laboratory of Cell Biology, NHLBI, National Institutes of Health, Bethesda, MD, USA
| | - Pietro De Camilli
- Departments of Neuroscience and Cell Biology, Howard Hughes Medical Institute, Program in Cellular Neuroscience, Neurodegeneration and Repair, Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, 06510, USA
- Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD, USA
| | - Mian Cao
- Programme in Neuroscience and Behavioural Disorders, Duke-NUS Medical School, Singapore, Singapore.
- Department of Physiology, National University of Singapore, Singapore, Singapore.
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4
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Mátyás A, Borbély E, Mihály A. Hippocampal Sclerosis in Pilocarpine Epilepsy: Survival of Peptide-Containing Neurons and Learning and Memory Disturbances in the Adult NMRI Strain Mouse. Int J Mol Sci 2021; 23:ijms23010204. [PMID: 35008630 PMCID: PMC8745054 DOI: 10.3390/ijms23010204] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 12/21/2021] [Accepted: 12/23/2021] [Indexed: 12/28/2022] Open
Abstract
The present experiments reveal the alterations of the hippocampal neuronal populations in chronic epilepsy. The mice were injected with a single dose of pilocarpine. They had status epilepticus and spontaneously recurrent motor seizures. Three months after pilocarpine treatment, the animals were investigated with the Barnes maze to determine their learning and memory capabilities. Their hippocampi were analyzed 2 weeks later (at 3.5 months) with standard immunohistochemical methods and cell counting. Every animal displayed hippocampal sclerosis. The neuronal loss was evaluated with neuronal-N immunostaining, and the activation of the microglia was measured with Iba1 immunohistochemistry. The neuropeptide Y, parvalbumin, and calretinin immunoreactive structures were qualitatively and quantitatively analyzed in the hippocampal formation. The results were compared statistically to the results of the control mice. We detected neuronal loss and strongly activated microglia populations. Neuropeptide Y was significantly upregulated in the sprouting axons. The number of parvalbumin- and calretinin-containing interneurons decreased significantly in the Ammon’s horn and dentate gyrus. The epileptic animals displayed significantly worse learning and memory functions. We concluded that degeneration of the principal neurons, a numerical decrease of PV-containing GABAergic neurons, and strong peptidergic axonal sprouting were responsible for the loss of the hippocampal learning and memory functions.
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Affiliation(s)
- Adrienne Mátyás
- Department of Anatomy, Albert Szent-Györgyi Faculty of Medicine, University of Szeged, Kossuth L. sgt. 38, H-6724 Szeged, Hungary;
| | - Emőke Borbély
- Department of Medical Chemistry, University of Szeged, Dóm tér. 8, H-6720 Szeged, Hungary;
- Professional Pedagogical Service of Csongrád-Csanád County, Űrhajós u. 4, H-6723 Szeged, Hungary
| | - András Mihály
- Department of Anatomy, Albert Szent-Györgyi Faculty of Medicine, University of Szeged, Kossuth L. sgt. 38, H-6724 Szeged, Hungary;
- Correspondence:
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5
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Kohek SRB, Foresti ML, Blanco MM, Cavarsan CF, da Silva CS, Mello LE. Anxious Profile Influences Behavioral and Immunohistological Findings in the Pilocarpine Model of Epilepsy. Front Pharmacol 2021; 12:640715. [PMID: 34025410 PMCID: PMC8132119 DOI: 10.3389/fphar.2021.640715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 03/22/2021] [Indexed: 12/01/2022] Open
Abstract
Anxiety and epilepsy have a complex bidirectional relationship, where a depressive/anxious condition is a factor that can trigger seizures which in turn can aggravate the depressive/anxious condition. In addition, brain structures such as the hippocampus and amygdala might have a critical relevance in both epilepsy and anxiety. The aim of the present work was to investigate the influence of different anxious profiles to epileptogenesis. Initially, animals were screened through the elevated plus-maze anxiety test, and then seizure development was evaluated using the pilocarpine model of epilepsy. There were no differences in the susceptibility to status epilepticus, mortality rate or frequency of spontaneous recurrent seizures between animals characterized as anxious as compared to the non-anxious animals. Next, we evaluated immunohistological patterns related to seizures and anxiety in various related brain areas. Despite a decrease in the density of neuropeptide Y and parvalbumin expression in epileptic animals, those presenting greater neuropeptide Y immunoreactivity in various brain regions, also showed higher spontaneous recurrent seizures frequency. Differences on the anxious profile showed to interfere with some of these findings in some regions. In addition, animals that were injected with pilocarpine, but did not develop status epilepticus, had behavioral and neuroanatomical alterations as compared to control animals, indicating its importance as an additional tool for investigating the heterogeneity of the epileptogenic response after an initial insult. This study allowed to better understand the association between anxiety and temporal lobe epilepsy and might allow for therapeutic targets to be developed to minimize the negative impacts associated with it.
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Affiliation(s)
| | | | | | - Clarissa Fantin Cavarsan
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, United States.,George and Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI, United States
| | | | - Luiz E Mello
- Physiology Department, Universidade Federal de São Paulo, São Paulo, Brazil.,Instituto D' Or de Pesquisa e Ensino, Rio de Janeiro, Brazil
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6
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Cattaneo S, Verlengia G, Marino P, Simonato M, Bettegazzi B. NPY and Gene Therapy for Epilepsy: How, When,... and Y. Front Mol Neurosci 2021; 13:608001. [PMID: 33551745 PMCID: PMC7862707 DOI: 10.3389/fnmol.2020.608001] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 12/21/2020] [Indexed: 12/18/2022] Open
Abstract
Neuropeptide Y (NPY) is a neuropeptide abundantly expressed in the mammalian central and peripheral nervous system. NPY is a pleiotropic molecule, which influences cell proliferation, cardiovascular and metabolic function, pain and neuronal excitability. In the central nervous system, NPY acts as a neuromodulator, affecting pathways that range from cellular (excitability, neurogenesis) to circuit level (food intake, stress response, pain perception). NPY has a broad repertoire of receptor subtypes, each activating specific signaling pathways in different tissues and cellular sub-regions. In the context of epilepsy, NPY is thought to act as an endogenous anticonvulsant that performs its action through Y2 and Y5 receptors. In fact, its overexpression in the brain with the aid of viral vectors can suppress seizures in animal models of epilepsy. Therefore, NPY-based gene therapy may represent a novel approach for the treatment of epilepsy patients, particularly for pharmaco-resistant and genetic forms of the disease. Nonetheless, considering all the aforementioned aspects of NPY signaling, the study of possible NPY applications as a therapeutic molecule is not devoid of critical aspects. The present review will summarize data related to NPY biology, focusing on its anti-epileptic effects, with a critical appraisal of key elements that could be exploited to improve the already existing NPY-based gene therapy approaches for epilepsy.
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Affiliation(s)
- Stefano Cattaneo
- Vita-Salute San Raffaele University, Milan, Italy.,San Raffaele Scientific Institute, Milan, Italy
| | - Gianluca Verlengia
- San Raffaele Scientific Institute, Milan, Italy.,Department of Neuroscience and Rehabilitation, Section of Pharmacology, University of Ferrara, Ferrara, Italy
| | - Pietro Marino
- Department of Neuroscience and Rehabilitation, Section of Pharmacology, University of Ferrara, Ferrara, Italy.,Department of Medical Sciences, Section of Pediatrics, University of Ferrara, Ferrara, Italy
| | - Michele Simonato
- Vita-Salute San Raffaele University, Milan, Italy.,San Raffaele Scientific Institute, Milan, Italy.,Department of Neuroscience and Rehabilitation, Section of Pharmacology, University of Ferrara, Ferrara, Italy
| | - Barbara Bettegazzi
- Vita-Salute San Raffaele University, Milan, Italy.,San Raffaele Scientific Institute, Milan, Italy
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7
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Alviña K, Jodeiri Farshbaf M, Mondal AK. Long term effects of stress on hippocampal function: Emphasis on early life stress paradigms and potential involvement of neuropeptide Y. J Neurosci Res 2021; 99:57-66. [PMID: 32162350 DOI: 10.1002/jnr.24614] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 02/06/2020] [Accepted: 02/27/2020] [Indexed: 01/06/2023]
Abstract
The brain is both central in orchestrating the response to stress, and, a very sensitive target when such response is not controlled. In fact, stress has long been associated with the onset and/or exacerbation of several neuropsychiatric disorders such as anxiety, depression, and drug addiction. The hippocampus is a key brain region involved in the response to stress, not only due to its anatomical connections with the hypothalamic-pituitary-adrenal axis but also as a major target of stress mediators. The hippocampal dentate gyrus (DG)-CA3 circuit, composed of DG granule cells axons (mossy fibers) synapsing onto CA3 pyramidal cells, plays an essential role in memory encoding and retrieval, functions that are vulnerable to stress. Although naturally excitatory, this circuit is under the inhibitory control of GABAergic interneurons that maintain the excitation/inhibition balance. One subgroup of such interneurons produces neuropeptide Y (NPY), which has emerged as a promising endogenous stress "resilience molecule" due to its anxiolytic and anti-epileptic properties. Here we examine existing evidence that reveals a potential role for hilar NPY+ interneurons in mediating stress-induced changes in hippocampal function. We will focus specifically on rodent models of early life stress (ELS), defined as adverse conditions during the early postnatal period that can have profound consequences for neurodevelopment. Collectively, these findings suggest that the long-lasting effects of ELS might stem from the loss of GABAergic NPY+ cells, which then can lead to reduced inhibition in the DG-CA3 pathway. Such change might then lead to hyperexcitability and concomitant hippocampal-dependent behavioral deficits.
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Affiliation(s)
- Karina Alviña
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
- Department of Neuroscience, University of Florida, Gainesville, FL, USA
| | | | - Amit Kumar Mondal
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
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8
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Wong VSC, Meadows M, Goldberg D, Willis DE. Semaphorin 3A induces acute changes in membrane excitability in spiral ganglion neurons in vitro. Eur J Neurosci 2019; 50:1741-1758. [PMID: 30706560 DOI: 10.1111/ejn.14360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 01/10/2019] [Accepted: 01/23/2019] [Indexed: 11/29/2022]
Abstract
The development and survival of spiral ganglion neurons (SGNs) are dependent on multiple trophic factors as well as membrane electrical activity. Semaphorins (Sema) constitute a family of membrane-associated and secreted proteins that have garnered significant attention as a potential SGN "navigator" during cochlea development. Previous studies using mutant mice demonstrated that Sema3A plays a role in the SGN pathfinding. The mechanisms, however, by which Sema3A shapes SGNs firing behavior are not known. In these studies, we found that Sema3A plays a novel role in regulating SGN resting membrane potential and excitability. Using dissociated SGN from pre-hearing (P3-P5) and post-hearing mice (P12-P15), we recorded membrane potentials using whole-cell patch clamp recording techniques in apical and basal SGN populations. Recombinant Sema3A was applied to examine the effects on intrinsic membrane properties and action potentials evoked by current injections. Apical and basal SGNs from newborn mice treated with recombinant Sema3A (100 ng/ml) displayed a higher resting membrane potential, higher threshold, decreased amplitude, and prolonged latency and duration of spikes. Although a similar phenomenon was observed in SGNs from post-hearing mice, the resting membrane potential was essentially indistinguishable before and after Sema3A exposure. Sema3A-mediated changes in membrane excitability were associated with a significant decrease in K+ and Ca2+ currents. Sema3A acts through linopirdine-sensitive K+ channels in apical, but not in the basal SGNs. Therefore, Sema3A induces differential effects in SGN membrane excitability that are dependent on age and location, and constitutes an additional early and novel effect of Sema3A SGNs in vitro.
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Affiliation(s)
| | - Marc Meadows
- The Vollum Institute, Oregon Health and Science University, Portland, Oregon
| | - David Goldberg
- The Burke Neurological Institute, White Plains, New York
| | - Dianna E Willis
- The Burke Neurological Institute, White Plains, New York.,Brain and Mind Research Institute, Weill Cornell Medicine, New York, New York
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9
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Cui Z, Zhang X, Song H, Yang F, Feng S, Feng L, Ling Z, Pan L, Liang S, Mao Z, Bu B, Chen L, Yu X, Xu B. Differential long non-coding RNA (lncRNA) profiles associated with hippocampal sclerosis in human mesial temporal lobe epilepsy. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2019; 12:259-266. [PMID: 31933741 PMCID: PMC6944018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 12/20/2018] [Indexed: 06/10/2023]
Abstract
OBJECTIVE The aim of this study was to analyze the expression profiles of long non-coding RNA (lncRNAs) in human mesial temporal lobe epilepsy (MTLE) with hippocampal sclerosis (HS) and to detect the functions of lncRNAs in epileptogenesis in MTLE. MATERIALS AND METHODS We used microarray analysis to analyze the differential expression of lncRNAs and mRNAs in three hippocampal sclerosis and three normal hippocampus samples. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to verify the microarrray results. A coding and non-coding gene co-expression network was constructed based on the correlation between the differential expression of lncRNAs and mRNAs. Gene ontology (GO) and pathway analyses were then performed to determine the potential roles of the differentially expressed mRNAs in the co-expression network. Lastly, to understand potential functions of lncRNAs in MTLE, cis-/trans-acting lncRNAs were predicted using bioinformatic analysis. RESULTS Compared with control hippocampus, 497 differentially expressed lncRNAs were identified in the hippocampal sclerosis samples, consisting of 294 up-regulated and 203 down-regulated lncRNAs (fold-change >2.0 or <-2.0, P<0.05). Similarly, 399 differentially expressed mRNAs were identified with 236 up-regulated and 163 down-regulated. There were 356 lncRNAs and 332 mRNAs in the non-coding and coding co-expression network, in which the highly enriched GO categories were related to the inflammatory response, and neuropeptide receptor activity. Nine pairs of lncRNAs and mRNAs (located within 10 kb of each other) were found to exert functional effects on epileptogenesis. CONCLUSION Differential expression of lncRNAs of varying length and location were observed in human MTLE with hippocampal sclerosis. The dysregulated lncRNAs with co-dysregulated mRNAs in inflammatory response and neuropeptide receptor activity categories are predicted to play roles in epileptogenesis in MTLE. LncRNA RP11-414J4 may contribute to epileptogenesis by targeting CPLX3.
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Affiliation(s)
- Zhiqiang Cui
- Department of Neurosurgery, Chinese PLA General Hospital, Chinese PLA Postgraduate Medical SchoolBeijing 100853, China
- Department of Neurosurgery, Affiliated Tangshan People’s Hospital and Tangshan Cancer Hospital North China University of Science and TechnologyTangshan 063000, China
| | - Xiufeng Zhang
- Department of Neurosurgery, Affiliated Hospital of Shanxi Medical University, Shanxi Provincial People’s HospitalTaiyuan 030012, China
| | - Huifang Song
- Department of Neurology, Beijing Sport University HospitalBeijing 100084, China
| | - Fuxing Yang
- Department of Neurosurgery, Chinese PLA General Hospital, Chinese PLA Postgraduate Medical SchoolBeijing 100853, China
| | - Shiyu Feng
- Department of Neurosurgery, Chinese PLA General Hospital, Chinese PLA Postgraduate Medical SchoolBeijing 100853, China
| | - Lin Feng
- Department of Pathology, Chinese PLA General Hospital, Chinese PLA Postgraduate Medical SchoolBeijing 100853, China
| | - Zhipei Ling
- Department of Neurosurgery, Chinese PLA General Hospital, Chinese PLA Postgraduate Medical SchoolBeijing 100853, China
| | - Longsheng Pan
- Department of Neurosurgery, Chinese PLA General Hospital, Chinese PLA Postgraduate Medical SchoolBeijing 100853, China
| | - Shuli Liang
- Department of Neurosurgery, Chinese PLA General Hospital, Chinese PLA Postgraduate Medical SchoolBeijing 100853, China
| | - Zhiqi Mao
- Department of Neurosurgery, Chinese PLA General Hospital, Chinese PLA Postgraduate Medical SchoolBeijing 100853, China
| | - Bo Bu
- Department of Neurosurgery, Chinese PLA General Hospital, Chinese PLA Postgraduate Medical SchoolBeijing 100853, China
| | - Lifeng Chen
- Department of Neurosurgery, Chinese PLA General Hospital, Chinese PLA Postgraduate Medical SchoolBeijing 100853, China
| | - Xinguang Yu
- Department of Neurosurgery, Chinese PLA General Hospital, Chinese PLA Postgraduate Medical SchoolBeijing 100853, China
| | - Bainan Xu
- Department of Neurosurgery, Chinese PLA General Hospital, Chinese PLA Postgraduate Medical SchoolBeijing 100853, China
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10
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Cavarsan CF, Malheiros J, Hamani C, Najm I, Covolan L. Is Mossy Fiber Sprouting a Potential Therapeutic Target for Epilepsy? Front Neurol 2018; 9:1023. [PMID: 30555406 PMCID: PMC6284045 DOI: 10.3389/fneur.2018.01023] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 11/13/2018] [Indexed: 11/13/2022] Open
Abstract
Mesial temporal lobe epilepsy (MTLE) caused by hippocampal sclerosis is one of the most frequent focal epilepsies in adults. It is characterized by focal seizures that begin in the hippocampus, sometimes spread to the insulo-perisylvian regions and may progress to secondary generalized seizures. Morphological alterations in hippocampal sclerosis are well defined. Among them, hippocampal sclerosis is characterized by prominent cell loss in the hilus and CA1, and abnormal mossy fiber sprouting (granular cell axons) into the dentate gyrus inner molecular layer. In this review, we highlight the role of mossy fiber sprouting in seizure generation and hippocampal excitability and discuss the response of alternative treatment strategies in terms of MFS and spontaneous recurrent seizures in models of TLE (temporal lobe epilepsy).
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Affiliation(s)
- Clarissa F Cavarsan
- Department of Physiology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Jackeline Malheiros
- Department of Physiology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Clement Hamani
- Department of Physiology, Universidade Federal de São Paulo, São Paulo, Brazil.,Harquail Centre for Neuromodulation, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada
| | - Imad Najm
- Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Luciene Covolan
- Department of Physiology, Universidade Federal de São Paulo, São Paulo, Brazil.,Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH, United States
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11
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Soares JI, Valente MC, Andrade PA, Maia GH, Lukoyanov NV. Reorganization of the septohippocampal cholinergic fiber system in experimental epilepsy. J Comp Neurol 2017; 525:2690-2705. [PMID: 28472854 DOI: 10.1002/cne.24235] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 04/11/2017] [Accepted: 04/24/2017] [Indexed: 12/28/2022]
Abstract
The septohippocampal cholinergic neurotransmission has long been implicated in seizures, but little is known about the structural features of this projection system in epileptic brain. We evaluated the effects of experimental epilepsy on the areal density of cholinergic terminals (fiber varicosities) in the dentate gyrus. For this purpose, we used two distinct post-status epilepticus rat models, in which epilepsy was induced with injections of either kainic acid or pilocarpine. To visualize the cholinergic fibers, we used brain sections immunostained for the vesicular acetylcholine transporter. It was found that the density of cholinergic fiber varicosities was higher in epileptic rats versus control rats in the inner and outer zones of the dentate molecular layer, but it was reduced in the dentate hilus. We further evaluated the effects of kainate treatment on the total number, density, and soma volume of septal cholinergic cells, which were visualized in brain sections stained for either vesicular acetylcholine transporter or choline acetyltransferase (ChAT). Both the number of septal cells with cholinergic phenotype and their density were increased in epileptic rats when compared to control rats. The septal cells stained for vesicular acetylcholine transporter, but not for ChAT, have enlarged perikarya in epileptic rats. These results revealed previously unknown details of structural reorganization of the septohippocampal cholinergic system in experimental epilepsy, involving fiber sprouting into the dentate molecular layer and a parallel fiber retraction from the dentate hilus. We hypothesize that epilepsy-related neuroplasticity of septohippocampal cholinergic neurons is capable of increasing neuronal excitability of the dentate gyrus.
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Affiliation(s)
- Joana I Soares
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal.,Neuronal Networks Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal.,Departamento de Biologia Experimental, Faculdade de Medicina da Universidade do Porto, Porto, Portugal.,Programa Doutoral em Neurociências, Universidade do Porto, Porto, Portugal
| | - Maria C Valente
- Departamento de Biologia Experimental, Faculdade de Medicina da Universidade do Porto, Porto, Portugal
| | - Pedro A Andrade
- Programa Doutoral em Neurociências, Universidade do Porto, Porto, Portugal.,Department of Neurobiology, A.I. Virtanen Institute, University of Eastern Finland, Kuopio, Finland
| | - Gisela H Maia
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal.,Neuronal Networks Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal.,Departamento de Biologia Experimental, Faculdade de Medicina da Universidade do Porto, Porto, Portugal.,Programa Doutoral em Neurociências, Universidade do Porto, Porto, Portugal
| | - Nikolai V Lukoyanov
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal.,Neuronal Networks Group, Instituto de Biologia Molecular e Celular da Universidade do Porto, Porto, Portugal.,Departamento de Anatomia, Faculdade de Medicina da Universidade do Porto, Porto, Portugal
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12
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Reichmann F, Wegerer V, Jain P, Mayerhofer R, Hassan AM, Fröhlich EE, Bock E, Pritz E, Herzog H, Holzer P, Leitinger G. Environmental enrichment induces behavioural disturbances in neuropeptide Y knockout mice. Sci Rep 2016; 6:28182. [PMID: 27305846 PMCID: PMC4910086 DOI: 10.1038/srep28182] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 05/31/2016] [Indexed: 12/28/2022] Open
Abstract
Environmental enrichment (EE) refers to the provision of a complex and stimulating housing condition which improves well-being, behaviour and brain function of laboratory animals. The mechanisms behind these beneficial effects of EE are only partially understood. In the current report, we describe a link between EE and neuropeptide Y (NPY), based on findings from NPY knockout (KO) mice exposed to EE. Relative to EE-housed wildtype (WT) animals, NPY KO mice displayed altered behaviour as well as molecular and morphological changes in amygdala and hippocampus. Exposure of WT mice to EE reduced anxiety and decreased central glucocorticoid receptor expression, effects which were absent in NPY KO mice. In addition, NPY deletion altered the preference of EE items, and EE-housed NPY KO mice responded to stress with exaggerated hyperthermia, displayed impaired spatial memory, had higher hippocampal brain-derived neurotrophic factor mRNA levels and altered hippocampal synaptic plasticity, effects which were not seen in WT mice. Accordingly, these findings suggest that NPY contributes to the anxiolytic effect of EE and that NPY deletion reverses the beneficial effects of EE into a negative experience. The NPY system could thus be a target for “enviromimetics”, therapeutics which reproduce the beneficial effects of enhanced environmental stimulation.
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Affiliation(s)
- Florian Reichmann
- Research Unit of Translational Neurogastroenterology, Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, 8010 Graz, Austria
| | - Vanessa Wegerer
- Research Unit Electron Microscopic Techniques, Institute of Cell Biology, Histology and Embryology, Medical University of Graz, Harrachgasse 21, 8010 Graz, Austria
| | - Piyush Jain
- Research Unit of Translational Neurogastroenterology, Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, 8010 Graz, Austria
| | - Raphaela Mayerhofer
- Research Unit of Translational Neurogastroenterology, Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, 8010 Graz, Austria
| | - Ahmed M Hassan
- Research Unit of Translational Neurogastroenterology, Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, 8010 Graz, Austria
| | - Esther E Fröhlich
- Research Unit of Translational Neurogastroenterology, Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, 8010 Graz, Austria
| | - Elisabeth Bock
- Research Unit Electron Microscopic Techniques, Institute of Cell Biology, Histology and Embryology, Medical University of Graz, Harrachgasse 21, 8010 Graz, Austria
| | - Elisabeth Pritz
- Research Unit Electron Microscopic Techniques, Institute of Cell Biology, Histology and Embryology, Medical University of Graz, Harrachgasse 21, 8010 Graz, Austria
| | - Herbert Herzog
- Neuroscience Division, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, Sydney, NSW 2010, Australia
| | - Peter Holzer
- Research Unit of Translational Neurogastroenterology, Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, 8010 Graz, Austria
| | - Gerd Leitinger
- Research Unit Electron Microscopic Techniques, Institute of Cell Biology, Histology and Embryology, Medical University of Graz, Harrachgasse 21, 8010 Graz, Austria
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13
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Otsuka S, Ohkido T, Itakura M, Watanabe S, Yamamori S, Iida Y, Saito M, Miyaoka H, Takahashi M. Dual mechanisms of rapid expression of anxiety-related behavior in pilocarpine-treated epileptic mice. Epilepsy Res 2016; 123:55-67. [PMID: 27132018 DOI: 10.1016/j.eplepsyres.2016.04.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Revised: 04/13/2016] [Accepted: 04/22/2016] [Indexed: 10/21/2022]
Abstract
A mouse model of epilepsy was generated by inducing status epilepticus (SE) for either 1.5 or 4.5h with pilocarpine to study anxiety-related behaviors, changes in the electroencephalogram of the cerebral cortex and hippocampus, and expression of hippocampal proteins. The viability and rate of success of SE induction were high in C57BL/6N mice but not in C57BL/6J mice. C57BL/6N mice were immotile during the first 2days after SE; however, by the third day, most mice were recovered and exhibited strong anxiety-related behaviors in response to the light/dark preference test and open field test. There was a striking difference in the temporal appearance of anxiety-related behavior between the two SE durations: 1.5h SE mice exhibited strong anxiety-related behavior 3days after SE that gradually attenuated over the next few weeks, whereas 4.5h SE mice exhibited strong anxiety-related behavior 3days after SE that persisted even at nearly 1year after SE. Mice receiving both SE durations exhibited generalized seizures (GS) after SE; however, there was a marked difference in the timing and duration of GS appearance. Mice in the 4.5h SE group exhibited spontaneous GS from 4days to at least 96days after SE. In contrast, mice in the 1.5h SE group exhibited GS only within the first several days after SE; however, epileptic spike clusters continuously appeared in the cerebral cortex and hippocampus for up to twelve days after SE. Among the hippocampal proteins tested, only brain derived-neurotrophic factor (BDNF) exhibited altered expression in parallel with anxiety-related behavior. These results showed the possibility that BDNF expression in the hippocampus might cause anxiety-related behavior in adulthood.
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Affiliation(s)
- Shintaro Otsuka
- Kitasato University Graduate School of Medical Sciences, 1-15-1 Kitasato, Minami-ku, Sagamihara-shi, Kanagawa 252-0374, Japan.
| | - Taro Ohkido
- Kitasato University Graduate School of Medical Sciences, 1-15-1 Kitasato, Minami-ku, Sagamihara-shi, Kanagawa 252-0374, Japan.
| | - Makoto Itakura
- Department of Biochemistry, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara-shi, Kanagawa 252-0374, Japan.
| | - Shigeru Watanabe
- Department of Psychiatry, Kitasato University School of Medicine, 2-1-1 Asamizodai, Minami-ku, Sagamihara-shi, Kanagawa 252-0380, Japan.
| | - Saori Yamamori
- Department of Biochemistry, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara-shi, Kanagawa 252-0374, Japan.
| | - Yuuki Iida
- Department of Psychiatry, Kitasato University School of Medicine, 2-1-1 Asamizodai, Minami-ku, Sagamihara-shi, Kanagawa 252-0380, Japan.
| | - Masanori Saito
- Department of Psychiatry, Kitasato University School of Medicine, 2-1-1 Asamizodai, Minami-ku, Sagamihara-shi, Kanagawa 252-0380, Japan.
| | - Hitoshi Miyaoka
- Department of Psychiatry, Kitasato University School of Medicine, 2-1-1 Asamizodai, Minami-ku, Sagamihara-shi, Kanagawa 252-0380, Japan.
| | - Masami Takahashi
- Kitasato University Graduate School of Medical Sciences, 1-15-1 Kitasato, Minami-ku, Sagamihara-shi, Kanagawa 252-0374, Japan; Department of Biochemistry, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara-shi, Kanagawa 252-0374, Japan.
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14
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Thom M. Review: Hippocampal sclerosis in epilepsy: a neuropathology review. Neuropathol Appl Neurobiol 2015; 40:520-43. [PMID: 24762203 PMCID: PMC4265206 DOI: 10.1111/nan.12150] [Citation(s) in RCA: 328] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 04/23/2014] [Indexed: 12/12/2022]
Abstract
Hippocampal sclerosis (HS) is a common pathology encountered in mesial temporal lobe epilepsy (MTLE) as well as other epilepsy syndromes and in both surgical and post-mortem practice. The 2013 International League Against Epilepsy (ILAE) classification segregates HS into typical (type 1) and atypical (type 2 and 3) groups, based on the histological patterns of subfield neuronal loss and gliosis. In addition, granule cell reorganization and alterations of interneuronal populations, neuropeptide fibre networks and mossy fibre sprouting are distinctive features of HS associated with epilepsies; they can be useful diagnostic aids to discriminate from other causes of HS, as well as highlighting potential mechanisms of hippocampal epileptogenesis. The cause of HS remains elusive and may be multifactorial; the contribution of febrile seizures, genetic susceptibility, inflammatory and neurodevelopmental factors are discussed. Post-mortem based research in HS, as an addition to studies on surgical samples, has the added advantage of enabling the study of the wider network changes associated with HS, the long-term effects of epilepsy on the pathology and associated comorbidities. It is likely that HS is heterogeneous in aspects of its cause, epileptogenetic mechanisms, network alterations and response to medical and surgical treatments. Future neuropathological studies will contribute to better recognition and understanding of these clinical and patho-aetiological subtypes of HS.
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Affiliation(s)
- Maria Thom
- Departments of Neuropathology and Clinical and Experimental Epilepsy, Institute of Neurology, University College London, London, UK
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15
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Olivetti PR, Maheshwari A, Noebels JL. Neonatal estradiol stimulation prevents epilepsy in Arx model of X-linked infantile spasms syndrome. Sci Transl Med 2014; 6:220ra12. [PMID: 24452264 DOI: 10.1126/scitranslmed.3007231] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Infantile spasms are a catastrophic form of pediatric epilepsy with inadequate treatment. In patients, mutation of ARX, a transcription factor selectively expressed in neuronal precursors and adult inhibitory interneurons, impairs cell migration and causes a major inherited subtype of the disease X-linked infantile spasms syndrome. Using an animal model, the Arx((GCG)10+7) mouse, we determined that brief estradiol (E2) administration during early postnatal development prevented spasms in infancy and seizures in adult mutants. E2 was ineffective when delivered after puberty or 30 days after birth. Early E2 treatment altered mRNA levels of three downstream targets of Arx (Shox2, Ebf3, and Lgi1) and restored depleted interneuron populations without increasing GABAergic synaptic density. Postnatal E2 treatment may induce lasting transcriptional changes that lead to enduring disease modification and could potentially serve as a therapy for inherited interneuronopathies.
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Affiliation(s)
- Pedro R Olivetti
- Blue Bird Circle Developmental Neurogenetics Laboratory, Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
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16
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Aydin C, Oztan O, Isgor C. Hippocampal Y2 receptor-mediated mossy fiber plasticity is implicated in nicotine abstinence-related social anxiety-like behavior in an outbred rat model of the novelty-seeking phenotype. Pharmacol Biochem Behav 2014; 125:48-54. [PMID: 25158103 DOI: 10.1016/j.pbb.2014.08.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 08/12/2014] [Accepted: 08/17/2014] [Indexed: 10/24/2022]
Abstract
Experimentally naïve outbred rats display varying rates of locomotor reactivity in response to the mild stress of a novel environment. Namely, some display high rates (HR) whereas some display low rates (LR) of locomotor reactivity. Previous reports from our laboratory show that HRs, but not LRs, develop locomotor sensitization to a low dose nicotine challenge and exhibit increased social anxiety-like behavior following chronic intermittent nicotine training. Moreover, the hippocampus, specifically hippocampal Y2 receptor (Y2R)-mediated neuropeptide Y signaling is implicated in these nicotine-induced behavioral effects observed in HRs. The present study examines the structural substrates of the expression of locomotor sensitization to a low dose nicotine challenge and associated social anxiety-like behavior following chronic intermittent nicotine exposure during adolescence in the LRHR hippocampi. Our data showed that the expression of locomotor sensitization to the low dose nicotine challenge and the increase in social anxiety-like behavior were accompanied by an increase in mossy fiber terminal field size, as well as an increase in spinophilin mRNA levels in the hippocampus in nicotine pre-trained HRs compared to saline pre-trained controls. Furthermore, a novel, selective Y2R antagonist administered systemically during 1 wk of abstinence reversed the behavioral, molecular and neuromorphological effects observed in nicotine-exposed HRs. These results suggest that nicotine-induced neuroplasticity within the hippocampus may regulate abstinence-related negative affect in HRs, and implicate hippocampal Y2R in vulnerability to the behavioral and neuroplastic effects of nicotine in the novelty-seeking phenotype.
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Affiliation(s)
- Cigdem Aydin
- Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL 33431, United States.
| | - Ozge Oztan
- Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL 33431, United States
| | - Ceylan Isgor
- Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL 33431, United States
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17
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Botterill JJ, Guskjolen AJ, Marks WN, Caruncho HJ, Kalynchuk LE. Limbic but not non-limbic kindling impairs conditioned fear and promotes plasticity of NPY and its Y2 receptor. Brain Struct Funct 2014; 220:3641-55. [PMID: 25146309 DOI: 10.1007/s00429-014-0880-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 08/13/2014] [Indexed: 12/01/2022]
Abstract
Epileptic seizures negatively affect cognition. However, the mechanisms that contribute to cognitive impairments after seizures are largely unknown. Here, we examined the effects of long-term kindling (i.e., 99 stimulations) of limbic (basolateral amygdala, dorsal hippocampus) and non-limbic (caudate nucleus) brain sites on conditioned fear and hippocampal plasticity. We first showed that kindling had no effect on acquisition of a hippocampal-dependent trace fear-conditioning task but limbic kindling impaired the retrieval of these fear memories. To determine the relationship between memory and hippocampal neuronal activity, we examined the expression of Fos protein 90 min after memory retrieval (i.e., 4 days after the last kindling stimulation). We found that limbic kindling, but not non-limbic kindling, decreased Fos expression in the granule cell layer, hilus, CA3 pyramidal cell layer, and CA1 pyramidal cell layer. Next, to investigate a mechanism that could contribute to dampen hippocampal neuronal activity in limbic-kindled rats, we focused on the endogenous anticonvulsant neuropeptide Y (NPY), which is expressed in a subset of GABAergic interneurons and can prevent glutamate release through interactions with its Y2 receptor. We found that limbic kindling significantly decreased the number of NPY-immunoreactive cells in several hippocampal subfields despite minimal staining of the neurodegenerative marker Fluoro-Jade B. However, we also noted that limbic kindling enhanced NPY immunoreactivity throughout the mossy fiber pathway. In these same regions, we observed limbic kindling-induced de novo expression of the NPY Y2 receptor. These novel findings demonstrate the site-specific effects of kindling on cognition and NPY plasticity, and they provide evidence that altered hippocampal NPY after limbic seizures coincides with dampened neural activity and cognitive impairments.
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Affiliation(s)
- J J Botterill
- Department of Psychology, University of Saskatchewan, Saskatoon, SK, S7N 5A5, Canada
| | - A J Guskjolen
- Department of Psychology, University of Saskatchewan, Saskatoon, SK, S7N 5A5, Canada
| | - W N Marks
- Department of Psychology, University of Saskatchewan, Saskatoon, SK, S7N 5A5, Canada
| | - H J Caruncho
- College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK, S7N 5A5, Canada
| | - L E Kalynchuk
- Department of Medicine, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, S7N 5E5, Canada.
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18
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McCall NM, Sprow GM, Delpire E, Thiele TE, Kash TL, Pleil KE. Effects of sex and deletion of neuropeptide Y2 receptors from GABAergic neurons on affective and alcohol drinking behaviors in mice. Front Integr Neurosci 2013; 7:100. [PMID: 24399943 PMCID: PMC3872329 DOI: 10.3389/fnint.2013.00100] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 12/08/2013] [Indexed: 12/13/2022] Open
Abstract
A large literature has demonstrated that neuropeptide Y (NPY) regulates many emotional and reward-related behaviors via its primary receptors, Y1R and Y2R. Classically, NPY actions at postsynaptic Y1R decrease anxiety, depression, and alcohol drinking, while its actions at presynaptic Y2R produce the opposite behavioral phenotypes. However, emerging evidence suggests that activation of Y2R can also produce anxiolysis in a brain region and neurotransmitter system-dependent fashion. Further, numerous human and rodent studies have reported that females display higher levels of anxiety, depression, and alcohol drinking. In this study, we evaluated sex differences and the role of Y2R on GABAergic transmission in these behaviors using a novel transgenic mouse that lacks Y2R specifically in VGAT-expressing neurons (VGAT-Y2R knockout). First, we confirmed our genetic manipulation by demonstrating that Y2R protein expression was decreased and that a Y2R agonist could not alter GABAergic transmission in the extended amygdala, a limbic brain region critically implicated in the regulation of anxiety and alcohol drinking behaviors, using immunofluorescence and slice electrophysiology. Then, we tested male and female VGAT-Y2R knockout mice on a series of behavioral assays for anxiety, depression, fear, anhedonia, and alcohol drinking. We found that females displayed greater basal anxiety, higher levels of ethanol consumption, and faster fear conditioning than males, and that knockout mice exhibited enhanced depressive-like behavior in the forced swim test. Together, these results confirm previous studies that demonstrate higher expression of negative affective and alcohol drinking behaviors in females than males, and they highlight the importance of Y2R function in GABAergic systems in the expression of depressive-like behavior.
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Affiliation(s)
- Nora M McCall
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine Chapel Hill, NC, USA ; Department of Pharmacology, University of North Carolina School of Medicine Chapel Hill, NC, USA
| | - Gretchen M Sprow
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine Chapel Hill, NC, USA ; Department of Psychology, University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University Nashville, TN, USA ; Department of Molecular Physiology and Biophysics, Vanderbilt University Nashville, TN, USA
| | - Todd E Thiele
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine Chapel Hill, NC, USA ; Department of Psychology, University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Thomas L Kash
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine Chapel Hill, NC, USA ; Department of Pharmacology, University of North Carolina School of Medicine Chapel Hill, NC, USA
| | - Kristen E Pleil
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine Chapel Hill, NC, USA ; Department of Pharmacology, University of North Carolina School of Medicine Chapel Hill, NC, USA
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19
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Marx M, Haas CA, Häussler U. Differential vulnerability of interneurons in the epileptic hippocampus. Front Cell Neurosci 2013; 7:167. [PMID: 24098270 PMCID: PMC3787650 DOI: 10.3389/fncel.2013.00167] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 09/07/2013] [Indexed: 11/30/2022] Open
Abstract
The loss of hippocampal interneurons has been considered as one reason for the onset of temporal lobe epilepsy (TLE) by shifting the excitation-inhibition balance. Yet, there are many different interneuron types which show differential vulnerability in the context of an epileptogenic insult. We used the intrahippocampal kainate (KA) mouse model for TLE in which a focal, unilateral KA injection induces status epilepticus (SE) followed by development of granule cell dispersion (GCD) and hippocampal sclerosis surrounding the injection site but not in the intermediate and temporal hippocampus. In this study, we characterized the loss of interneurons with respect to septotemporal position and to differential vulnerability of interneuron populations. To this end, we performed intrahippocampal recordings of the initial SE, in situ hybridization for glutamic acid decarboxylase 67 (GAD67) mRNA and immunohistochemistry for parvalbumin (PV) and neuropeptide Y (NPY) in the early phase of epileptogenesis at 2 days and at 21 days after KA injection, when recurrent epileptic activity and GCD have fully developed. We show that SE extended along the entire septotemporal axis of both hippocampi, but was stronger at distant sites than at the injection site. There was an almost complete loss of interneurons surrounding the injection site and expanding to the intermediate hippocampus already at 2 days but increasing until 21 days after KA. Furthermore, we observed differential vulnerability of PV- and NPY-expressing cells: while the latter were lost at the injection site but preserved at intermediate sites, PV-expressing cells were gone even at sites more temporal than GCD. In addition, we found upregulation of GAD67 mRNA expression in dispersed granule cells and of NPY staining in ipsilateral granule cells and ipsi- and contralateral mossy fibers. Our data thus indicate differential survival capacity of interneurons in the epileptic hippocampus and compensatory plasticity mechanisms depending on the hippocampal position.
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Affiliation(s)
- Markus Marx
- Experimental Epilepsy Research, Department of Neurosurgery, University of Freiburg Freiburg, Germany
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20
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Malva JO, Xapelli S, Baptista S, Valero J, Agasse F, Ferreira R, Silva AP. Multifaces of neuropeptide Y in the brain--neuroprotection, neurogenesis and neuroinflammation. Neuropeptides 2012; 46:299-308. [PMID: 23116540 DOI: 10.1016/j.npep.2012.09.001] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 09/17/2012] [Accepted: 09/25/2012] [Indexed: 12/20/2022]
Abstract
Neuropeptide Y (NPY) has been implicated in the modulation of important features of neuronal physiology, including calcium homeostasis, neurotransmitter release and excitability. Moreover, NPY has been involved as an important modulator of hippocampal and thalamic circuits, receiving particular attention as an endogenous antiepileptic peptide and as a potential master regulator of feeding behavior. NPY not only inhibits excessive glutamate release (decreasing circuitry hyperexcitability) but also protects neurons from excitotoxic cell death. Furthermore, NPY has been involved in the modulation of the dynamics of dentate gyrus and subventricular zone neural stem cell niches. In both regions, NPY is part of the chemical resource of the neurogenic niche and acts through NPY Y1 receptors to promote neuronal differentiation. Interestingly, NPY is also considered a neuroimmune messenger. In this review, we highlight recent evidences concerning paracrine/autocrine actions of NPY involved in neuroprotection, neurogenesis and neuroinflammation. In summary, the three faces of NPY, discussed in the present review, may contribute to better understand the dynamics and cell fate decision in the brain parenchyma and in restricted areas of neurogenic niches, in health and disease.
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Affiliation(s)
- J O Malva
- Laboratory of Biochemistry and Cell Biology, Faculty of Medicine, University of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal.
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21
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Corvino V, Marchese E, Giannetti S, Lattanzi W, Bonvissuto D, Biamonte F, Mongiovì AM, Michetti F, Geloso MC. The neuroprotective and neurogenic effects of neuropeptide Y administration in an animal model of hippocampal neurodegeneration and temporal lobe epilepsy induced by trimethyltin. J Neurochem 2012; 122:415-26. [DOI: 10.1111/j.1471-4159.2012.07770.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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22
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BACE1 elevation is associated with aberrant limbic axonal sprouting in epileptic CD1 mice. Exp Neurol 2012; 235:228-37. [PMID: 22265658 DOI: 10.1016/j.expneurol.2012.01.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2011] [Revised: 12/25/2011] [Accepted: 01/04/2012] [Indexed: 12/20/2022]
Abstract
The brain is capable of remarkable synaptic reorganization following stress and injury, often using the same molecular machinery that governs neurodevelopment. This form of plasticity is crucial for restoring and maintaining network function. However, neurodegeneration and subsequent reorganization can also play a role in disease pathogenesis, as is seen in temporal lobe epilepsy and Alzheimer's disease. β-Secretase-1 (BACE1) is a protease known for cleaving β-amyloid precursor protein into β-amyloid (Aβ), a major constituent in amyloid plaques. Emerging evidence suggests that BACE1 is also involved with synaptic plasticity and nerve regeneration. Here we examined whether BACE1 immunoreactivity (IR) was altered in pilocarpine-induced epileptic CD1 mice in a manner consistent with the synaptic reorganization seen during epileptogenesis. BACE1-IR increased in the CA3 mossy fiber field and dentate inner molecular layer in pilocarpine-induced epileptic mice, relative to controls (saline-treated mice and mice 24-48 h after pilocarpine-status), and paralleled aberrant expression of neuropeptide Y. Regionally increased BACE1-IR also occurred in neuropil in hippocampal area CA1 and in subregions of the amygdala and temporal cortex in epileptic mice, colocalizing with increased IR for growth associated protein 43 (GAP43) and polysialylated-neural cell adhesion molecule (PSA-NCAM), but reduced IR for microtubule-associated protein 2 (MAP2). These findings suggest that BACE1 is involved in aberrant limbic axonal sprouting in a model of temporal lobe epilepsy, warranting further investigation into the role of BACE1 in physiological vs. pathological neuronal plasticity.
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23
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Ferreira R, Santos T, Cortes L, Cochaud S, Agasse F, Silva AP, Xapelli S, Malva JO. Neuropeptide Y inhibits interleukin-1 beta-induced microglia motility. J Neurochem 2011; 120:93-105. [DOI: 10.1111/j.1471-4159.2011.07541.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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24
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Károly N, Mihály A, Dobó E. Comparative immunohistochemistry of synaptic markers in the rodent hippocampus in pilocarpine epilepsy. Acta Histochem 2011; 113:656-62. [PMID: 20846710 DOI: 10.1016/j.acthis.2010.08.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Revised: 08/17/2010] [Accepted: 08/18/2010] [Indexed: 11/26/2022]
Abstract
Pilocarpine-induced epileptic state (Status epilepticus) generates an aberrant sprouting of hippocampal mossy fibers, which alter the intrahippocampal circuits. The mechanisms of the synaptic plasticity remain to be determined. In our studies in mice and rats, pilocarpine-induced seizures were done in order to gain information on the process of synaptogenesis. After a 2-month survival period, changes in the levels of synaptic markers (GAP-43 and Syn-I) were examined in the hippocampus by means of semi-quantitative immunohistochemistry. Mossy fiber sprouting (MFS) was examined in each brain using Timm's sulphide-silver method. Despite the marked behavioral manifestations caused by pilocarpine treatment, only 40% of the rats and 56% of the mice showed MFS. Pilocarpine treatment significantly reduced the GAP-43 immunoreactivity in the inner molecular layer in both species, with some minor differences in the staining pattern. Syn-I immunohistochemistry revealed species differences in the sprouting process. The strong immunoreactive band of the inner molecular layer in rats corresponded to the Timm-positive ectopic mossy fibers. The staining intensity in this layer, representing the ectopic mossy fibers, was weak in the mouse. The Syn-I immunoreactivity decreased significantly in the hilum, where Timm's method also demonstrated enhanced sprouting. This proved that, while sprouted axons displayed strong Syn-I staining in rats, ectopic mossy fibers in mice did not express this synaptic marker. The species variability in the expression of synaptic markers in sprouted axons following pilocarpine treatment indicated different synaptic mechanisms of epileptogenesis.
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Shetty AK. Promise of resveratrol for easing status epilepticus and epilepsy. Pharmacol Ther 2011; 131:269-86. [PMID: 21554899 PMCID: PMC3133838 DOI: 10.1016/j.pharmthera.2011.04.008] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Accepted: 03/29/2011] [Indexed: 12/26/2022]
Abstract
Resveratrol (RESV; 3,5,4'-tri-hydroxy stilbene), a naturally occurring phytoalexin, is found at a high concentration in the skin of red grapes and red wine. RESV mediates a wide-range of biological activities, which comprise an increased life span, anti-ischemic, anti-cancer, antiviral, anti-aging and anti-inflammatory properties. Studies in several animal prototypes of brain injury suggest that RESV is an effective neuroprotective compound. Ability to enter the brain after a peripheral administration and no adverse effects on the brain or body are other features that are appealing for using this compound as a therapy for brain injury or neurodegenerative diseases. The goal of this review is to discuss the promise of RESV for treating acute seizures, preventing the acute seizure or status epilepticus induced development of chronic epilepsy, and easing the chronic epilepsy typified by spontaneous recurrent seizures and cognitive dysfunction. First, the various beneficial effects of RESV on the normal brain are discussed to provide a rationale for considering RESV treatment in the management of acute seizures and epilepsy. Next, the detrimental effects of acute seizures or status epilepticus on the hippocampus and the implications of post-status epilepticus changes in the hippocampus towards the occurrence of chronic epilepsy and cognitive dysfunction are summarized. The final segment evaluates studies that have used RESV as a neuroprotective compound against seizures, and proposes studies that are critically needed prior to the clinical application of RESV as a prophylaxis against the development of chronic epilepsy and cognitive dysfunction after an episode of status epilepticus or head injury.
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Affiliation(s)
- Ashok K Shetty
- Medical Research and Surgery Services, Veterans Affairs Medical Center, Durham, NC 27705, USA.
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Robertson CR, Flynn SP, White HS, Bulaj G. Anticonvulsant neuropeptides as drug leads for neurological diseases. Nat Prod Rep 2011; 28:741-62. [PMID: 21340067 DOI: 10.1039/c0np00048e] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Anticonvulsant neuropeptides are best known for their ability to suppress seizures and modulate pain pathways. Galanin, neuropeptide Y, somatostatin, neurotensin, dynorphin, among others, have been validated as potential first-in-class anti-epileptic or/and analgesic compounds in animal models of epilepsy and pain, but their therapeutic potential extends to other neurological indications, including neurodegenerative and psychatric disorders. Disease-modifying properties of neuropeptides make them even more attractive templates for developing new-generation neurotherapeutics. Arguably, efforts to transform this class of neuropeptides into drugs have been limited compared to those for other bioactive peptides. Key challenges in developing neuropeptide-based anticonvulsants are: to engineer optimal receptor-subtype selectivity, to improve metabolic stability and to enhance their bioavailability, including penetration across the blood–brain barrier (BBB). Here, we summarize advances toward developing systemically active and CNS-penetrant neuropeptide analogs. Two main objectives of this review are: (1) to provide an overview of structural and pharmacological properties for selected anticonvulsant neuropeptides and their analogs and (2) to encourage broader efforts to convert these endogenous natural products into drug leads for pain, epilepsy and other neurological diseases.
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Affiliation(s)
- Charles R Robertson
- College of Pharmacy, Department of Medicinal Chemistry, 421 Wakara Way, STE. 360 Salt Lake City, UT 84108, USA
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27
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Arc regulates spine morphology and maintains network stability in vivo. Proc Natl Acad Sci U S A 2010; 107:18173-8. [PMID: 20921410 DOI: 10.1073/pnas.1006546107] [Citation(s) in RCA: 189] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Long-term memory relies on modulation of synaptic connections in response to experience. This plasticity involves trafficking of AMPA receptors (AMPAR) and alteration of spine morphology. Arc, a gene induced by synaptic activity, mediates the endocytosis of AMPA receptors and is required for both long-term and homeostatic plasticity. We found that Arc increases spine density and regulates spine morphology by increasing the proportion of thin spines. Furthermore, Arc specifically reduces surface GluR1 internalization at thin spines, and Arc mutants that fail to facilitate AMPAR endocytosis do not increase the proportion of thin spines, suggesting that Arc-mediated AMPAR endocytosis facilitates alterations in spine morphology. Thus, by linking spine morphology with AMPAR endocytosis, Arc balances synaptic downscaling with increased structural plasticity. Supporting this, loss of Arc in vivo leads to a significant decrease in the proportion of thin spines and an epileptic-like network hyperexcitability.
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Ghosal K, Pimplikar SW. Aging and excitotoxic stress exacerbate neural circuit reorganization in amyloid precursor protein intracellular domain transgenic mice. Neurobiol Aging 2010; 32:2320.e1-9. [PMID: 20493588 DOI: 10.1016/j.neurobiolaging.2010.04.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Revised: 04/06/2010] [Accepted: 04/20/2010] [Indexed: 11/27/2022]
Abstract
The cleavage of amyloid precursor protein (APP) by presenilins simultaneously generates amyloid-β (Aβ) and APP intracellular Domain (AICD) peptides. Aβ plays a pivotal role in Alzheimer's disease (AD) pathology and recently AICD was also shown to contribute to AD. Transgenic mice overexpressing AICD show age-dependent tau phosphorylation and aggregation, memory deficits, and neurodegeneration. Moreover, these mice show aberrant electrical activity and silent seizures beginning at 3-4 months of age. Here we show that AICD mice also displayed abnormal mossy fiber sprouting beginning about the same time and that this sprouting intensified as the animals aged. Expression of neuropeptide Y was increased in mossy fiber terminals in aged but not young AICD mice. Importantly, young AICD mice injected with kainic acid showed similar pathology to that observed in aged AICD mice. These data show that elevated levels of AICD render neurons hypersensitive to stress and induce hippocampal circuit reorganization, which can further exacerbate hyperexcitability. These results further demonstrate that AICD, in addition to Aβ, can play a significant role in AD pathogenesis.
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Affiliation(s)
- Kaushik Ghosal
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
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Anticonvulsant effects and behavioural outcomes of rAAV serotype 1 vector-mediated neuropeptide Y overexpression in rat hippocampus. Gene Ther 2010; 17:643-52. [DOI: 10.1038/gt.2010.23] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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Naegele JR, Maisano X, Yang J, Royston S, Ribeiro E. Recent advancements in stem cell and gene therapies for neurological disorders and intractable epilepsy. Neuropharmacology 2010; 58:855-64. [PMID: 20146928 DOI: 10.1016/j.neuropharm.2010.01.019] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Revised: 01/22/2010] [Accepted: 01/26/2010] [Indexed: 12/11/2022]
Abstract
The potential applications of stem cell therapies for treating neurological disorders are enormous. Many laboratories are focusing on stem cell treatments for CNS diseases, including spinal cord injury, Amyotrophic lateral sclerosis, Parkinson's disease, Huntington's disease, multiple sclerosis, stroke, traumatic brain injury, and epilepsy. Among the many stem cell types under testing for neurological treatments, the most common are fetal and adult brain stem cells, embryonic stem cells, induced pluripotent stem cells, and mesenchymal stem cells. An expanding toolbox of molecular probes is now available to allow analyses of neural stem cell fates prior to and after transplantation. Concomitantly, protocols are being developed to direct the fates of stem cell-derived neural progenitors, and also to screen stem cells for tumorigenicity and aneuploidy. The rapid progress in the field suggests that novel stem cell and gene therapies for neurological disorders are in the pipeline.
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Affiliation(s)
- Janice R Naegele
- Department of Biology and Program in Neuroscience and Behavior, Hall Atwater Laboratory, 52 Lawn Avenue, Wesleyan University, Middletown, CT 06459, USA.
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31
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Vision and the hypothalamus. ACTA ACUST UNITED AC 2010; 81:100-15. [DOI: 10.1016/j.optm.2009.07.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Revised: 06/04/2009] [Accepted: 07/13/2009] [Indexed: 01/01/2023]
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Dunleavy M, Shinoda S, Schindler C, Ewart C, Dolan R, Gobbo OL, Kerskens CM, Henshall DC. Experimental neonatal status epilepticus and the development of temporal lobe epilepsy with unilateral hippocampal sclerosis. THE AMERICAN JOURNAL OF PATHOLOGY 2009; 176:330-42. [PMID: 19948825 DOI: 10.2353/ajpath.2010.090119] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Hippocampal sclerosis is a common pathological finding in patients with temporal lobe epilepsy, including children, but a causal relationship to early-life seizures remains in question. Neonatal status epilepticus in animals can result in neuronal death within the hippocampus, although macroscopic features of hippocampal shrinkage are not evident at adulthood. Here, we examined electrophysiological and pathological consequences of focally evoked status epilepticus triggered by intra-amygdala microinjection of kainic acid in postnatal day 10 rat pups. Neonatal status epilepticus resulted in extensive neuronal death in the ipsilateral hippocampal CA1 and CA3 subfields and hilus, as assessed by DNA fragmentation and Fluoro-Jade B staining 72 hours later. The contralateral hippocampus was not significantly damaged. Histopathology at P55/P65 revealed unilateral hippocampal sclerosis (grade IV, modified Wyler/Watson scale) comprising >50% CA1 and CA3 neuron loss and astrogliosis. Additional features included hydrocephalus ex vacuo, modest dentate granule cell layer widening, and altered neuropeptide Y immunoreactivity indicative of synaptic rearrangement. Hippocampal atrophy was also evident on magnetic resonance imaging. Depth electrode recordings at adulthood detected spontaneous seizures that involved the ipsilateral hippocampus and amygdala. A significant positive correlation was found between hippocampal pathology grade and both frequency and duration of epileptic seizures at adulthood. The current study demonstrates that experimental neonatal status epilepticus can result in classical unilateral hippocampal sclerosis and temporal lobe epilepsy.
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Affiliation(s)
- Mark Dunleavy
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin 2, Ireland
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Thom M, Martinian L, Catarino C, Yogarajah M, Koepp MJ, Caboclo L, Sisodiya SM. Bilateral reorganization of the dentate gyrus in hippocampal sclerosis: a postmortem study. Neurology 2009; 73:1033-40. [PMID: 19710404 DOI: 10.1212/wnl.0b013e3181b99a07] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Hippocampal sclerosis (HS) is the most common surgical pathology associated with mesial temporal lobe epilepsy (MTLE). HS is typically characterized by mossy fiber sprouting (MFS) and reorganization of neuropeptide Y (NPY) fiber networks in the dentate gyrus. One potential cause of postoperative seizure recurrence following temporal lobe surgery may be the presence of seizure-associated bilateral hippocampal damage. We aimed to investigate patterns of hippocampal abnormalities in a postmortem series as identified by NPY and dynorphin immunohistochemistry. METHODS Analysis of dentate gyrus fiber reorganization, using dynorphin (to demonstrate MFS) and NPY immunohistochemistry, was carried out in a postmortem epilepsy series of 25 cases (age range 21-96 years). In 9 patients, previously refractory seizures had become well controlled for up to 34 years prior to death. RESULTS Bilateral MFS or abnormal NPY patterns were seen in 15 patients including those with bilateral symmetric, asymmetric, and unilateral HS by conventional histologic criteria. MFS and NPY reorganization was present in all classical HS cases, more variably in atypical HS, present in both MTLE and non-MTLE syndromes and with seizure histories of up to 92 years, despite seizure remission in some patients. CONCLUSION Synaptic reorganization in the dentate gyrus may be a bilateral, persistent process in epilepsy. It is unlikely to be sufficient to generate seizures and more likely to represent a seizure-induced phenomenon.
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Affiliation(s)
- M Thom
- Department of Clinical and Experimental Epilepsy, Division of Neuropathology, Institute of Neurology, Queen Square, London, UK.
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Brooks-Kayal AR, Raol YH, Russek SJ. Alteration of epileptogenesis genes. Neurotherapeutics 2009; 6:312-8. [PMID: 19332325 PMCID: PMC2700027 DOI: 10.1016/j.nurt.2009.01.019] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Accepted: 01/23/2009] [Indexed: 01/03/2023] Open
Abstract
Retrospective studies suggest that precipitating events such as prolonged seizures, stroke, or head trauma increase the risk of developing epilepsy later in life. The process of epilepsy development, known as epileptogenesis, is associated with changes in the expression of a myriad of genes. One of the major challenges for the epilepsy research community has been to determine which of these changes contributes to epileptogenesis, which may be compensatory, and which may be noncontributory. Establishing this for any given gene is essential if it is to be considered a therapeutic target for the prevention or treatment of epilepsy. Our laboratories have examined alterations in gene expression related to inhibitory neurotransmission that have been proposed as contributing factors in epileptogenesis. The GABA(A) receptor mediates most fast synaptic inhibition, and changes in GABA(A) receptor subunit expression and function have been reported in adult animals beginning immediately after prolonged seizures (status epilepticus [SE]) and continue as animals become chronically epileptic. Prevention of GABA(A) receptor subunit changes after SE using viral gene transfer inhibits development of epilepsy in an animal model, suggesting that these changes directly contribute to epileptogenesis. The mechanisms that regulate differential expression of GABA(A) receptor subunits in hippocampus after SE have recently been identified, and include the CREB-ICER, JAK-STAT, BDNF, and Egr3 signaling pathways. Targeting signaling pathways that alter the expression of genes involved in epileptogenesis may provide novel therapeutic approaches for preventing or inhibiting the development of epilepsy after a precipitating insult.
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Affiliation(s)
- Amy R Brooks-Kayal
- Division of Neurology, Department of Pediatrics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA.
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Tripathi PP, Sgadò P, Scali M, Viaggi C, Casarosa S, Simon HH, Vaglini F, Corsini GU, Bozzi Y. Increased susceptibility to kainic acid-induced seizures in Engrailed-2 knockout mice. Neuroscience 2009; 159:842-9. [PMID: 19186208 DOI: 10.1016/j.neuroscience.2009.01.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Revised: 12/30/2008] [Accepted: 01/01/2009] [Indexed: 12/27/2022]
Abstract
The En2 gene, coding for the homeobox-containing transcription factor Engrailed-2 (EN2), has been associated to autism spectrum disorder (ASD). Due to neuroanatomical and behavioral abnormalities, which partly resemble those observed in ASD patients, En2 knockout (En2(-/-)) mice have been proposed as a model for ASD. In the mouse embryo, En2 is involved in the specification of midbrain/hindbrain regions, being predominantly expressed in the developing cerebellum and ventral midbrain, and its expression is maintained in these structures until adulthood. Here we show that in the adult mouse brain, En2 mRNA is expressed also in the hippocampus and cerebral cortex. Hippocampal En2 mRNA content decreased after seizures induced by kainic acid (KA). This suggests that En2 might also influence the functioning of forebrain areas during adulthood and in response to seizures. Indeed, a reduced expression of parvalbumin and somatostatin was detected in the hippocampus of En2(-/-) mice as compared to wild-type (WT) mice, indicating an altered GABAergic innervation of limbic circuits in En2(-/-) mice. In keeping with these results, En2(-/-) mice displayed an increased susceptibility to KA-induced seizures. KA (20 mg/kg) determined more severe and prolonged generalized seizures in En2(-/-) mice, when compared to WT animals. Seizures were accompanied by a widespread c-fos and c-jun mRNA induction in the brain of En2(-/-) but not WT mice. Long-term histopathological changes (CA1 cell loss, upregulation of neuropeptide Y) also occurred in the hippocampus of KA-treated En2(-/-) but not WT mice. These findings suggest that En2(-/-) mice might be used as a novel tool to study the link between epilepsy and ASD.
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Affiliation(s)
- P P Tripathi
- Institute of Neuroscience, C.N.R., Pisa, Italy; Laboratory of Neurobiology, Scuola Normale Superiore, Pisa, Italy
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Gant JC, Thibault O, Blalock EM, Yang J, Bachstetter A, Kotick J, Schauwecker PE, Hauser KF, Smith GM, Mervis R, Li Y, Barnes GN. Decreased number of interneurons and increased seizures in neuropilin 2 deficient mice: implications for autism and epilepsy. Epilepsia 2008; 50:629-45. [PMID: 18657176 DOI: 10.1111/j.1528-1167.2008.01725.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
PURPOSE Clinically, perturbations in the semaphorin signaling system have been associated with autism and epilepsy. The semaphorins have been implicated in guidance, migration, differentiation, and synaptic plasticity of neurons. The semaphorin 3F (Sema3F) ligand and its receptor, neuropilin 2 (NPN2) are highly expressed within limbic areas. NPN2 signaling may intimately direct the apposition of presynaptic and postsynaptic locations, facilitating the development and maturity of hippocampal synaptic function. To further understand the role of NPN2 signaling in central nevous system (CNS) plasticity, structural and functional alterations were assessed in NPN2 deficient mice. METHODS In NPN2 deficient mice, we measured seizure susceptibility after kainic acid or pentylenetetrazol, neuronal excitability and synaptic throughput in slice preparations, principal and interneuron cell counts with immunocytochemical protocols, synaptosomal protein levels with immunoblots, and dendritic morphology with Golgi-staining. RESULTS NPN2 deficient mice had shorter seizure latencies, increased vulnerability to seizure-related death, were more likely to develop spontaneous recurrent seizure activity after chemical challenge, and had an increased slope on input/output curves. Principal cell counts were unchanged, but GABA, parvalbumin, and neuropeptide Y interneuron cell counts were significantly reduced. Synaptosomal NPN2 protein levels and total number of GABAergic synapses were decreased in a gene dose-dependent fashion. CA1 pyramidal cells showed reduced dendritic length and complexity, as well as an increased number of dendritic spines. DISCUSSION These data suggest the novel hypothesis that the Sema 3F signaling system's role in appropriate placement of subsets of hippocampal interneurons has critical downstream consequences for hippocampal function, resulting in a more seizure susceptible phenotype.
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Affiliation(s)
- John C Gant
- Departments of Molecular and Biomedical Pharmacology, University of Kentucky College of Medicine, Lexington, KY, USA
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