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Tan SY, Jiang JX, Huang HX, Mo XP, Feng JR, Chen Y, Yang L, Long C. Neural mechanism underlies CYLD modulation of morphology and synaptic function of medium spiny neurons in dorsolateral striatum. Front Mol Neurosci 2023; 16:1107355. [PMID: 36846565 PMCID: PMC9945542 DOI: 10.3389/fnmol.2023.1107355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 01/17/2023] [Indexed: 02/11/2023] Open
Abstract
Although the deubiquitinase cylindromatosis (CYLD), an abundant protein in the postsynaptic density fraction, plays a crucial role in mediating the synaptic activity of the striatum, the precise molecular mechanism remains largely unclear. Here, using a Cyld-knockout mouse model, we demonstrate that CYLD regulates dorsolateral striatum (DLS) neuronal morphology, firing activity, excitatory synaptic transmission, and plasticity of striatal medium spiny neurons via, likely, interaction with glutamate receptor 1 (GluA1) and glutamate receptor 2 (GluA2), two key subunits of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPARs). CYLD deficiency reduces levels of GluA1 and GluA2 surface protein and increases K63-linked ubiquitination, resulting in functional impairments both in AMPAR-mediated excitatory postsynaptic currents and in AMPAR-dependent long-term depression. The results demonstrate a functional association of CYLD with AMPAR activity, which strengthens our understanding of the role of CYLD in striatal neuronal activity.
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Affiliation(s)
- Shu-Yi Tan
- School of Life Sciences, South China Normal University, Guangzhou, China
| | - Jin-Xiang Jiang
- School of Life Sciences, South China Normal University, Guangzhou, China
| | - Hui-Xian Huang
- School of Life Sciences, South China Normal University, Guangzhou, China
| | - Xiu-Ping Mo
- School of Life Sciences, Guangzhou University, Guangzhou, China
| | - Jing-Ru Feng
- School of Life Sciences, South China Normal University, Guangzhou, China
| | - Yu Chen
- School of Life Sciences, South China Normal University, Guangzhou, China
| | - Li Yang
- School of Life Sciences, Guangzhou University, Guangzhou, China
| | - Cheng Long
- School of Life Sciences, South China Normal University, Guangzhou, China.,South China Normal University-Panyu Central Hospital Joint Laboratory of Translational Medical Research, Panyu Central Hospital, Guangzhou, China
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2
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Puhahn-Schmeiser B, Kleemann T, Jabbarli R, Bock HH, Beck J, Freiman TM. Granule cell dispersion in two mouse models of temporal lobe epilepsy and reeler mice is associated with changes in dendritic orientation and spine distribution. Hippocampus 2022; 32:517-528. [PMID: 35621370 DOI: 10.1002/hipo.23447] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 04/05/2022] [Accepted: 04/11/2022] [Indexed: 11/06/2022]
Abstract
Temporal lobe epilepsy is characterized by hippocampal neuronal death in CA1 and hilus. Dentate gyrus granule cells survive but show dispersion of the compact granule cell layer. This is associated with decrease of the glycoprotein Reelin, which regulates neuron migration and dendrite outgrow. Reelin-deficient (reeler) mice show no layering, their granule cells are dispersed throughout the dentate gyrus. We studied granule cell dendritic orientation and distribution of postsynaptic spines in reeler mice and two mouse models of temporal lobe epilepsy, namely the p35 knockout mice, which show Reelin-independent neuronal migration defects, and mice with unilateral intrahippocampal kainate injection. Granule cells were Golgi-stained and analyzed, using a computerized camera lucida system. Granule cells in naive controls exhibited a vertically oriented dendritic arbor with a small bifurcation angle if positioned proximal to the hilus and a wider dendritic bifurcation angle, if positioned distally. P35 knockout- and kainate-injected mice showed a dispersed granule cell layer, granule cells showed basal dendrites with wider bifurcation angles, which lost position-specific differences. Reeler mice lacked dendritic orientation. P35 knockout- and kainate-injected mice showed increased dendritic spine density in the granule cell layer. Molecular layer dendrites showed a reduced spine density in kainate-injected mice only, whereas in p35 knockouts no reduced spine density was seen. Reeler mice showed a homogenous high spine density. We hypothesize that granule cells migrate in temporal lobe epilepsy, develop new dendrites which show a spread of the dendritic tree, create new spines in areas proximal to mossy fiber sprouting, which is present in p35 knockout- and kainate-injected mice and loose spines on distal dendrites if mossy cell death is present, as it was in kainate-injected mice only. These results are in accordance with findings in epilepsy patients.
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Affiliation(s)
- Barbara Puhahn-Schmeiser
- Faculty of Medicine, Department of Neurosurgery, Medical Center, University of Freiburg, Freiburg, Germany
| | - Tobias Kleemann
- Department of Gastroenterology and Rheumatology, Carl-Thiem-Hospital, Cottbus, Germany
| | - Ramazan Jabbarli
- Faculty of Medicine, Department of Neurosurgery, Medical Center, University of Duisburg-Essen, Essen, Germany
| | - Hans H Bock
- Faculty of Medicine, Department of Gastroenterology, Hepatology and Infectiology, Medical Center, University of Duesseldorf, Duesseldorf, Germany
| | - Jürgen Beck
- Faculty of Medicine, Department of Neurosurgery, Medical Center, University of Freiburg, Freiburg, Germany
| | - Thomas M Freiman
- Department of Neurosurgery, University Medical Center Rostock, Rostock, Germany
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3
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Canto AM, Godoi AB, Matos AHB, Geraldis JC, Rogerio F, Alvim MKM, Yasuda CL, Ghizoni E, Tedeschi H, Veiga DFT, Henning B, Souza W, Rocha CS, Vieira AS, Dias EV, Carvalho BS, Gilioli R, Arul AB, Robinson RAS, Cendes F, Lopes-Cendes I. Benchmarking the proteomic profile of animal models of mesial temporal epilepsy. Ann Clin Transl Neurol 2022; 9:454-467. [PMID: 35238489 PMCID: PMC8994989 DOI: 10.1002/acn3.51533] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 02/21/2022] [Accepted: 02/23/2022] [Indexed: 12/20/2022] Open
Abstract
OBJECTIVES We compared the proteomic signatures of the hippocampal lesion induced in three different animal models of mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE+HS): the systemic pilocarpine model (PILO), the intracerebroventricular kainic acid model (KA), and the perforant pathway stimulation model (PPS). METHODS We used shotgun proteomics to analyze the proteomes and find enriched biological pathways of the dorsal and ventral dentate gyrus (DG) isolated from the hippocampi of the three animal models. We also compared the proteomes obtained in the animal models to that from the DG of patients with pharmacoresistant MTLE+HS. RESULTS We found that each animal model presents specific profiles of proteomic changes. The PILO model showed responses predominantly related to neuronal excitatory imbalance. The KA model revealed alterations mainly in synaptic activity. The PPS model displayed abnormalities in metabolism and oxidative stress. We also identified common biological pathways enriched in all three models, such as inflammation and immune response, which were also observed in tissue from patients. However, none of the models could recapitulate the profile of molecular changes observed in tissue from patients. SIGNIFICANCE Our results indicate that each model has its own set of biological responses leading to epilepsy. Thus, it seems that only using a combination of the three models may one replicate more closely the mechanisms underlying MTLE+HS as seen in patients.
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Affiliation(s)
- Amanda M Canto
- Department of Translational Medicine, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil.,Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, SP, Brazil
| | - Alexandre B Godoi
- Department of Translational Medicine, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil.,Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, SP, Brazil
| | - Alexandre H B Matos
- Department of Translational Medicine, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil.,Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, SP, Brazil
| | - Jaqueline C Geraldis
- Department of Translational Medicine, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil.,Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, SP, Brazil
| | - Fabio Rogerio
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, SP, Brazil.,Department of Pathology, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Marina K M Alvim
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, SP, Brazil.,Department of Neurology, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Clarissa L Yasuda
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, SP, Brazil.,Department of Neurology, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Enrico Ghizoni
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, SP, Brazil.,Department of Neurology, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Helder Tedeschi
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, SP, Brazil.,Department of Neurology, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Diogo F T Veiga
- Department of Translational Medicine, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil.,Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, SP, Brazil
| | - Barbara Henning
- Department of Translational Medicine, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil.,Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, SP, Brazil
| | - Welliton Souza
- Department of Translational Medicine, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil.,Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, SP, Brazil
| | - Cristiane S Rocha
- Department of Translational Medicine, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil.,Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, SP, Brazil
| | - André S Vieira
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, SP, Brazil.,Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Elayne V Dias
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, SP, Brazil.,Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Benilton S Carvalho
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, SP, Brazil.,Department of Statistics, Institute of Mathematics, Statistics and Scientific Computing, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Rovilson Gilioli
- Laboratory of Animal Quality Control, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Albert B Arul
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, 37235, USA
| | - Renã A S Robinson
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, 37235, USA
| | - Fernando Cendes
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, SP, Brazil.,Department of Neurology, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Iscia Lopes-Cendes
- Department of Translational Medicine, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil.,Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, SP, Brazil
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4
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Rossini L, De Santis D, Mauceri RR, Tesoriero C, Bentivoglio M, Maderna E, Maiorana A, Deleo F, de Curtis M, Tringali G, Cossu M, Tumminelli G, Bramerio M, Spreafico R, Tassi L, Garbelli R. Dendritic pathology, spine loss and synaptic reorganization in human cortex from epilepsy patients. Brain 2021; 144:251-265. [PMID: 33221837 DOI: 10.1093/brain/awaa387] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 08/06/2020] [Accepted: 09/07/2020] [Indexed: 12/26/2022] Open
Abstract
Neuronal dendritic arborizations and dendritic spines are crucial for a normal synaptic transmission and may be critically involved in the pathophysiology of epilepsy. Alterations in dendritic morphology and spine loss mainly in hippocampal neurons have been reported both in epilepsy animal models and in human brain tissues from patients with epilepsy. However, it is still unclear whether these dendritic abnormalities relate to the cause of epilepsy or are generated by seizure recurrence. We investigated fine neuronal structures at the level of dendritic and spine organization using Golgi impregnation, and analysed synaptic networks with immunohistochemical markers of glutamatergic (vGLUT1) and GABAergic (vGAT) axon terminals in human cerebral cortices derived from epilepsy surgery. Specimens were obtained from 28 patients with different neuropathologically defined aetiologies: type Ia and type II focal cortical dysplasia, cryptogenic (no lesion) and temporal lobe epilepsy with hippocampal sclerosis. Autoptic tissues were used for comparison. Three-dimensional reconstructions of Golgi-impregnated neurons revealed severe dendritic reshaping and spine alteration in the core of the type II focal cortical dysplasia. Dysmorphic neurons showed increased dendritic complexity, reduction of dendritic spines and occasional filopodia-like protrusions emerging from the soma. Surprisingly, the intermingled normal-looking pyramidal neurons also showed severe spine loss and simplified dendritic arborization. No changes were observed outside the dysplasia (perilesional tissue) or in neocortical postsurgical tissue obtained in the other patient groups. Immunoreactivities of vGLUT1 and vGAT showed synaptic reorganization in the core of type II dysplasia characterized by the presence of abnormal perisomatic baskets around dysmorphic neurons, in particular those with filopodia-like protrusions, and changes in vGLUT1/vGAT expression. Ultrastructural data in type II dysplasia highlighted the presence of altered neuropil engulfed by glial processes. Our data indicate that the fine morphological aspect of neurons and dendritic spines are normal in epileptogenic neocortex, with the exception of type II dysplastic lesions. The findings suggest that the mechanisms leading to this severe form of cortical malformation interfere with the normal dendritic arborization and synaptic network organization. The data argue against the concept that long-lasting epilepsy and seizure recurrence per se unavoidably produce a dendritic pathology.
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Affiliation(s)
- Laura Rossini
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Dalia De Santis
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | | | - Chiara Tesoriero
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Italy
| | - Marina Bentivoglio
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Italy
| | - Emanuela Maderna
- Division of Neurology V and Neuropathology, Fondazione IRCCS, Istituto Neurologico Carlo Besta, Milano, Italy
| | - Antonio Maiorana
- Institute of Pathology, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Francesco Deleo
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Marco de Curtis
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Giovanni Tringali
- Neurosurgery Unit, Fondazione IRCCS, Istituto Neurologico Carlo Besta, Milano, Italy
| | - Massimo Cossu
- "Claudio Munari" Epilepsy Surgery Center, GOM Niguarda, Milano, Italy
| | - Gemma Tumminelli
- "Claudio Munari" Epilepsy Surgery Center, GOM Niguarda, Milano, Italy
| | | | - Roberto Spreafico
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
| | - Laura Tassi
- "Claudio Munari" Epilepsy Surgery Center, GOM Niguarda, Milano, Italy
| | - Rita Garbelli
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milano, Italy
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5
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Ábrahám H, Molnár JE, Sóki N, Gyimesi C, Horváth Z, Janszky J, Dóczi T, Seress L. Etiology-related Degree of Sprouting of Parvalbumin-immunoreactive Axons in the Human Dentate Gyrus in Temporal Lobe Epilepsy. Neuroscience 2020; 448:55-70. [PMID: 32931846 DOI: 10.1016/j.neuroscience.2020.09.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 08/22/2020] [Accepted: 09/05/2020] [Indexed: 11/16/2022]
Abstract
In the present study, we examined parvalbumin-immunoreactive cells and axons in the dentate gyrus of surgically resected tissues of therapy-resistant temporal lobe epilepsy (TLE) patients with different etiologies. Based on MRI results, five groups of patients were formed: (1) hippocampal sclerosis (HS), (2) malformation of cortical development, (3) malformation of cortical development + HS, (4) tumor-induced TLE, (5) patients with negative MRI result. Four control samples were also included in the study. Parvalbumin-immunoreactive cells were observed mostly in subgranular location in the dentate hilus in controls, in tumor-induced TLE, in malformation of cortical development and in MR-negative cases. In patients with HS, significant decrease in the number of hilar parvalbumin-immunoreactive cells and large numbers of ectopic parvalbumin-containing neurons were detected in the dentate gyrus' molecular layer. The ratio of ectopic/normally-located cells was significantly higher in HS than in other TLE groups. In patients with HS, robust sprouting of parvalbumin-immunoreactive axons were frequently visible in the molecular layer. The extent of sprouting was significantly higher in TLE patients with HS than in other groups. Strong sprouting of parvalbumin-immunoreactive axons were frequently observed in patients who had childhood febrile seizure. Significant correlation was found between the level of sprouting of axons and the ratio of ectopic/normally-located parvalbumin-containing cells. Electron microscopy demonstrated that sprouted parvalbumin-immunoreactive axons terminate on proximal and distal dendritic shafts as well as on dendritic spines of granule cells. Our results indicate alteration of target profile of parvalbumin-immunoreactive neurons in HS that contributes to the known synaptic remodeling in TLE.
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Affiliation(s)
- Hajnalka Ábrahám
- Department of Medical Biology and Central Electron Microscopic Laboratory, University of Pécs Medical School, Szigeti u 12., Pécs 7624, Hungary.
| | - Judit E Molnár
- Department of Medical Biology and Central Electron Microscopic Laboratory, University of Pécs Medical School, Szigeti u 12., Pécs 7624, Hungary
| | - Noémi Sóki
- Department of Medical Biology and Central Electron Microscopic Laboratory, University of Pécs Medical School, Szigeti u 12., Pécs 7624, Hungary
| | - Csilla Gyimesi
- Department of Neurology, University of Pécs Medical School, Rét u. 2., Pécs 7623, Hungary
| | - Zsolt Horváth
- Department of Neurosurgery, University of Pécs Medical School, Rét u. 2., Pécs 7623, Hungary
| | - József Janszky
- Department of Neurology, University of Pécs Medical School, Rét u. 2., Pécs 7623, Hungary
| | - Tamás Dóczi
- Department of Neurosurgery, University of Pécs Medical School, Rét u. 2., Pécs 7623, Hungary
| | - László Seress
- Department of Medical Biology and Central Electron Microscopic Laboratory, University of Pécs Medical School, Szigeti u 12., Pécs 7624, Hungary
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6
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Chidambaram SB, Rathipriya AG, Bolla SR, Bhat A, Ray B, Mahalakshmi AM, Manivasagam T, Thenmozhi AJ, Essa MM, Guillemin GJ, Chandra R, Sakharkar MK. Dendritic spines: Revisiting the physiological role. Prog Neuropsychopharmacol Biol Psychiatry 2019; 92:161-193. [PMID: 30654089 DOI: 10.1016/j.pnpbp.2019.01.005] [Citation(s) in RCA: 156] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Revised: 01/04/2019] [Accepted: 01/12/2019] [Indexed: 12/11/2022]
Abstract
Dendritic spines are small, thin, specialized protrusions from neuronal dendrites, primarily localized in the excitatory synapses. Sophisticated imaging techniques revealed that dendritic spines are complex structures consisting of a dense network of cytoskeletal, transmembrane and scaffolding molecules, and numerous surface receptors. Molecular signaling pathways, mainly Rho and Ras family small GTPases pathways that converge on actin cytoskeleton, regulate the spine morphology and dynamics bi-directionally during synaptic activity. During synaptic plasticity the number and shapes of dendritic spines undergo radical reorganizations. Long-term potentiation (LTP) induction promote spine head enlargement and the formation and stabilization of new spines. Long-term depression (LTD) results in their shrinkage and retraction. Reports indicate increased spine density in the pyramidal neurons of autism and Fragile X syndrome patients and reduced density in the temporal gyrus loci of schizophrenic patients. Post-mortem reports of Alzheimer's brains showed reduced spine number in the hippocampus and cortex. This review highlights the spine morphogenesis process, the activity-dependent structural plasticity and mechanisms by which synaptic activity sculpts the dendritic spines, the structural and functional changes in spines during learning and memory using LTP and LTD processes. It also discusses on spine status in neurodegenerative diseases and the impact of nootropics and neuroprotective agents on the functional restoration of dendritic spines.
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Affiliation(s)
- Saravana Babu Chidambaram
- Department of Pharmacology, JSS College of Pharmacy, JSS Academy of Higher Education & Research (JSSAHER), Mysuru, Karnataka 570015, India.
| | - A G Rathipriya
- Food and Brain Research Foundation, Chennai, Tamil Nadu, India
| | - Srinivasa Rao Bolla
- Department of Anatomy, College of Medicine, Imam Abdulrahman Bin Faisal University, Damam, Saudi Arabia
| | - Abid Bhat
- Department of Pharmacology, JSS College of Pharmacy, JSS Academy of Higher Education & Research (JSSAHER), Mysuru, Karnataka 570015, India
| | - Bipul Ray
- Department of Pharmacology, JSS College of Pharmacy, JSS Academy of Higher Education & Research (JSSAHER), Mysuru, Karnataka 570015, India
| | - Arehally Marappa Mahalakshmi
- Department of Pharmacology, JSS College of Pharmacy, JSS Academy of Higher Education & Research (JSSAHER), Mysuru, Karnataka 570015, India
| | - Thamilarasan Manivasagam
- Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Annamalainagar, Tamilnadu, India
| | - Arokiasamy Justin Thenmozhi
- Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Annamalainagar, Tamilnadu, India
| | - Musthafa Mohamed Essa
- Department of Food Science and Nutrition, CAMS, Sultan Qaboos University, Muscat, Oman
| | - Gilles J Guillemin
- Neuropharmacology Group, Faculty of Medicine and Health Sciences, Deb Bailey MND Research Laboratory, Macquarie University, Sydney, NSW 2109, Australia
| | - Ramesh Chandra
- Department of Chemistry, Ambedkar Centre for BioMedical Research, Delhi University, Delhi 110007, India
| | - Meena Kishore Sakharkar
- College of Pharmacy and Nutrition, University of Saskatchewan, 107, Wiggins Road, Saskatoon, SK S7N 5C9, Canada.
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7
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Klein P, Dingledine R, Aronica E, Bernard C, Blümcke I, Boison D, Brodie MJ, Brooks-Kayal AR, Engel J, Forcelli PA, Hirsch LJ, Kaminski RM, Klitgaard H, Kobow K, Lowenstein DH, Pearl PL, Pitkänen A, Puhakka N, Rogawski MA, Schmidt D, Sillanpää M, Sloviter RS, Steinhäuser C, Vezzani A, Walker MC, Löscher W. Commonalities in epileptogenic processes from different acute brain insults: Do they translate? Epilepsia 2018; 59:37-66. [PMID: 29247482 PMCID: PMC5993212 DOI: 10.1111/epi.13965] [Citation(s) in RCA: 189] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/01/2017] [Indexed: 12/12/2022]
Abstract
The most common forms of acquired epilepsies arise following acute brain insults such as traumatic brain injury, stroke, or central nervous system infections. Treatment is effective for only 60%-70% of patients and remains symptomatic despite decades of effort to develop epilepsy prevention therapies. Recent preclinical efforts are focused on likely primary drivers of epileptogenesis, namely inflammation, neuron loss, plasticity, and circuit reorganization. This review suggests a path to identify neuronal and molecular targets for clinical testing of specific hypotheses about epileptogenesis and its prevention or modification. Acquired human epilepsies with different etiologies share some features with animal models. We identify these commonalities and discuss their relevance to the development of successful epilepsy prevention or disease modification strategies. Risk factors for developing epilepsy that appear common to multiple acute injury etiologies include intracranial bleeding, disruption of the blood-brain barrier, more severe injury, and early seizures within 1 week of injury. In diverse human epilepsies and animal models, seizures appear to propagate within a limbic or thalamocortical/corticocortical network. Common histopathologic features of epilepsy of diverse and mostly focal origin are microglial activation and astrogliosis, heterotopic neurons in the white matter, loss of neurons, and the presence of inflammatory cellular infiltrates. Astrocytes exhibit smaller K+ conductances and lose gap junction coupling in many animal models as well as in sclerotic hippocampi from temporal lobe epilepsy patients. There is increasing evidence that epilepsy can be prevented or aborted in preclinical animal models of acquired epilepsy by interfering with processes that appear common to multiple acute injury etiologies, for example, in post-status epilepticus models of focal epilepsy by transient treatment with a trkB/PLCγ1 inhibitor, isoflurane, or HMGB1 antibodies and by topical administration of adenosine, in the cortical fluid percussion injury model by focal cooling, and in the albumin posttraumatic epilepsy model by losartan. Preclinical studies further highlight the roles of mTOR1 pathways, JAK-STAT3, IL-1R/TLR4 signaling, and other inflammatory pathways in the genesis or modulation of epilepsy after brain injury. The wealth of commonalities, diversity of molecular targets identified preclinically, and likely multidimensional nature of epileptogenesis argue for a combinatorial strategy in prevention therapy. Going forward, the identification of impending epilepsy biomarkers to allow better patient selection, together with better alignment with multisite preclinical trials in animal models, should guide the clinical testing of new hypotheses for epileptogenesis and its prevention.
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Affiliation(s)
- Pavel Klein
- Mid-Atlantic Epilepsy and Sleep Center, Bethesda, MD, USA
| | | | - Eleonora Aronica
- Department of (Neuro) Pathology, Academic Medical Center and Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, The Netherlands
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, The Netherlands
| | - Christophe Bernard
- Aix Marseille Univ, Inserm, INS, Instit Neurosci Syst, Marseille, 13005, France
| | - Ingmar Blümcke
- Department of Neuropathology, University Hospital Erlangen, Erlangen, Germany
| | - Detlev Boison
- Robert Stone Dow Neurobiology Laboratories, Legacy Research Institute, Portland, OR, USA
| | - Martin J Brodie
- Epilepsy Unit, West Glasgow Ambulatory Care Hospital-Yorkhill, Glasgow, UK
| | - Amy R Brooks-Kayal
- Division of Neurology, Departments of Pediatrics and Neurology, University of Colorado School of Medicine, Aurora, CO, USA
- Children's Hospital Colorado, Aurora, CO, USA
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Jerome Engel
- Departments of Neurology, Neurobiology, and Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, Brain Research Institute, University of California, Los Angeles, CA, USA
| | | | | | | | | | - Katja Kobow
- Department of Neuropathology, University Hospital Erlangen, Erlangen, Germany
| | | | - Phillip L Pearl
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Asla Pitkänen
- Department of Neurobiology, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Noora Puhakka
- Department of Neurobiology, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Michael A Rogawski
- Department of Neurology, University of California, Davis, Sacramento, CA, USA
| | | | - Matti Sillanpää
- Departments of Child Neurology and General Practice, University of Turku and Turku University Hospital, Turku, Finland
| | - Robert S Sloviter
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA, USA
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Annamaria Vezzani
- Department of Neuroscience, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Institute for Pharmacological Research, Milan,, Italy
| | - Matthew C Walker
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK
| | - Wolfgang Löscher
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine, Hannover, Germany
- Center for Systems Neuroscience, Hannover, Germany
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8
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Araya R. Input transformation by dendritic spines of pyramidal neurons. Front Neuroanat 2014; 8:141. [PMID: 25520626 PMCID: PMC4251451 DOI: 10.3389/fnana.2014.00141] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 11/11/2014] [Indexed: 11/13/2022] Open
Abstract
In the mammalian brain, most inputs received by a neuron are formed on the dendritic tree. In the neocortex, the dendrites of pyramidal neurons are covered by thousands of tiny protrusions known as dendritic spines, which are the major recipient sites for excitatory synaptic information in the brain. Their peculiar morphology, with a small head connected to the dendritic shaft by a slender neck, has inspired decades of theoretical and more recently experimental work in an attempt to understand how excitatory synaptic inputs are processed, stored and integrated in pyramidal neurons. Advances in electrophysiological, optical and genetic tools are now enabling us to unravel the biophysical and molecular mechanisms controlling spine function in health and disease. Here I highlight relevant findings, challenges and hypotheses on spine function, with an emphasis on the electrical properties of spines and on how these affect the storage and integration of excitatory synaptic inputs in pyramidal neurons. In an attempt to make sense of the published data, I propose that the raison d'etre for dendritic spines lies in their ability to undergo activity-dependent structural and molecular changes that can modify synaptic strength, and hence alter the gain of the linearly integrated sub-threshold depolarizations in pyramidal neuron dendrites before the generation of a dendritic spike.
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Affiliation(s)
- Roberto Araya
- Department of Neurosciences, Faculty of Medicine, University of Montreal Montreal, QC, Canada
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9
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Zeng C, Zhou P, Jiang T, Yuan C, Ma Y, Feng L, Liu R, Tang W, Long X, Xiao B, Tian F. Upregulation and Diverse Roles of TRPC3 and TRPC6 in Synaptic Reorganization of the Mossy Fiber Pathway in Temporal Lobe Epilepsy. Mol Neurobiol 2014; 52:562-72. [PMID: 25213992 DOI: 10.1007/s12035-014-8871-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 08/15/2014] [Indexed: 11/28/2022]
Abstract
Temporal lobe epilepsy (TLE) is the most common form of intractable epilepsy and is always accompanied with hippocampal sclerosis. The molecular mechanism of this pathological phenomenon has been extensively explored, yet remains unclear. Previous studies suggest that ion channels, especially calcium channels, might play important roles. Transient receptor potential canonical channel (TRPC) is a novel cation channel dominantly permeable to Ca(2+) and widely expressed in the human brain. We measured the expression of two subtypes of TRPC channels, TRPC3 and TRPC6, in temporal lobe epileptic foci excised from patients with intractable epilepsy and in hippocampus of mice with pilocarpine-induced status epilepticus (SE), an animal model of TLE. Cortical TRPC3 and TRPC6 protein expressions were significantly higher in TLE patients compared with those in controls. Expression of TRPC3 and TRPC6 protein also increased significantly in the CA3 region of the hippocampus of SE mice. Inhibition of TRPC3 by intracerebroventricular injection of anti-TRPC3 antibody prevented aberrant-sprouted mossy fiber collaterals in the CA3 region, while inhibition of TRPC6 by anti-TRPC6 antibody reduced dendritic arborization and spine density of CA3 pyramidal neurons. Our results indicate that TRPC3 and TRPC6 participate diversely in synaptic reorganization in the mossy fiber pathway in TLE.
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Affiliation(s)
- Chang Zeng
- Health Management Center, Central South University, Changsha, China
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10
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Hester MS, Danzer SC. Hippocampal granule cell pathology in epilepsy - a possible structural basis for comorbidities of epilepsy? Epilepsy Behav 2014; 38:105-16. [PMID: 24468242 PMCID: PMC4110172 DOI: 10.1016/j.yebeh.2013.12.022] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 12/17/2013] [Accepted: 12/21/2013] [Indexed: 01/31/2023]
Abstract
Temporal lobe epilepsy in both animals and humans is characterized by abnormally integrated hippocampal dentate granule cells. Among other abnormalities, these cells make axonal connections with inappropriate targets, grow dendrites in the wrong direction, and migrate to ectopic locations. These changes promote the formation of recurrent excitatory circuits, leading to the appealing hypothesis that these abnormal cells may by epileptogenic. While this hypothesis has been the subject of intense study, less attention has been paid to the possibility that abnormal granule cells in the epileptic brain may also contribute to comorbidities associated with the disease. Epilepsy is associated with a variety of general findings, such as memory disturbances and cognitive dysfunction, and is often comorbid with a number of other conditions, including schizophrenia and autism. Interestingly, recent studies implicate disruption of common genes and gene pathways in all three diseases. Moreover, while neuropsychiatric conditions are associated with changes in a variety of brain regions, granule cell abnormalities in temporal lobe epilepsy appear to be phenocopies of granule cell deficits produced by genetic mouse models of autism and schizophrenia, suggesting that granule cell dysmorphogenesis may be a common factor uniting these seemingly diverse diseases. Disruption of common signaling pathways regulating granule cell neurogenesis may begin to provide mechanistic insight into the cooccurrence of temporal lobe epilepsy and cognitive and behavioral disorders.
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Affiliation(s)
- Michael S Hester
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Molecular and Developmental Biology Graduate Program, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Steve C Danzer
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Anesthesia, University of Cincinnati, Cincinnati, OH 45267, USA; Department of Pediatrics, University of Cincinnati, Cincinnati, OH 45267, USA; Molecular and Developmental Biology Graduate Program, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
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11
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Kandratavicius L, Rosa-Neto P, Monteiro MR, Guiot MC, Assirati JA, Carlotti CG, Kobayashi E, Leite JP. Distinct increased metabotropic glutamate receptor type 5 (mGluR5) in temporal lobe epilepsy with and without hippocampal sclerosis. Hippocampus 2013; 23:1212-30. [PMID: 23804486 PMCID: PMC4165311 DOI: 10.1002/hipo.22160] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/31/2013] [Indexed: 12/04/2022]
Abstract
Metabotropic glutamate receptor type 5 (mGluR5) upregulation in temporal lobe epilepsy (TLE) and the correlation of its expression with features of hippocampal sclerosis (HS) remains unclear. Here we characterized mGluR5 immunoreactivity in hippocampus, entorhinal cortex (EC), and subiculum of TLE specimens with confirmed HS, with neocortical TLE (non-HS) and necropsy controls. We correlated mGluR5 immunoreactivity with neuronal density, mossy fiber sprouting, astrogliosis (GFAP), and dendritic alterations (MAP2). TLE specimens showed increased mGluR5 expression, which was most pronounced in the EC, subiculum, CA2, and dentate gyrus outer molecular layer. Increased mGluR5 expression was seen in hippocampal head and body segments and was independent of neuronal density, astrogliosis, or dendritic alterations. Positive correlation between mGluR5 expression with mossy fiber sprouting and with MAP2 in CA3 and CA1 was found only in HS specimens. Negative correlation between mGluR5 expression with seizure frequency and epilepsy duration was found only in non-HS cases. Specimens from HS patients without previous history of febrile seizure (FS) showed higher mGluR5 and MAP2 expression in CA2. Our study suggests that mGluR5 upregulation is part of a repertoire of post-synaptic adaptations that might control overexcitation and excessive glutamate release rather than a dysfunction that leads to seizure facilitation. That would explain why non-HS cases, on which seizures are likely to originate outside the hippocampal formation, also exhibit upregulated mGluR5. On the other hand, lower mGluR5 expression was related to increased seizure frequency. In addition to its role in hyperexcitability, mGluR5 upregulation could play a role in counterbalance mechanisms along the hyperexcitable circuitry uniquely altered in sclerotic hippocampal formation. Inefficient post-synaptic compensatory morphological (dendritic branching) and glutamatergic (mGluR5 expression) mechanisms in CA2 subfield could potentially underlie the association of FS with HS and TLE. © 2013 Wiley Periodicals, Inc.
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Affiliation(s)
- Ludmyla Kandratavicius
- Department of Neurosciences and Behavior, Ribeirao Preto Medical School, University of Sao PauloBrazil
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill UniversityMontreal, Canada
| | - Pedro Rosa-Neto
- Translational Neuroimaging Laboratory, Department of Neurology and Neurosurgery, Douglas Research Institute, McGill UniversityMontreal, Canada
| | - Mariana Raquel Monteiro
- Department of Neurosciences and Behavior, Ribeirao Preto Medical School, University of Sao PauloBrazil
| | - Marie-Christine Guiot
- Department of Pathology, Montreal Neurological Institute, McGill UniversityMontreal, Canada
| | | | | | - Eliane Kobayashi
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill UniversityMontreal, Canada
| | - Joao Pereira Leite
- Department of Neurosciences and Behavior, Ribeirao Preto Medical School, University of Sao PauloBrazil
- *Correspondence to: Joao Pereira Leite, Ribeirao Preto Medical School, Department of Neurosciences and Behavior, University of Sao Paulo, Av Bandeirantes 3900, 14049-900, Ribeirao Preto, SP, Brazil. E-mail:
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12
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Dendritic spine pathology in epilepsy: cause or consequence? Neuroscience 2012; 251:141-50. [PMID: 22522469 DOI: 10.1016/j.neuroscience.2012.03.048] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 01/26/2012] [Accepted: 03/04/2012] [Indexed: 01/23/2023]
Abstract
Abnormalities in dendritic spines have commonly been observed in brain specimens from epilepsy patients and animal models of epilepsy. However, the functional implications and clinical consequences of this dendritic pathology for epilepsy are uncertain. Dendritic spine abnormalities may promote hyperexcitable circuits and seizures in some types of epilepsy, especially in specific genetic syndromes with documented dendritic pathology, but in these cases it is difficult to differentiate their effects on seizures versus other comorbidities, such as cognitive deficits and autism. In other situations, seizures themselves may cause damage to dendrites and dendritic spines and this seizure-induced brain injury may then contribute to progressive epileptogenesis, memory problems and other neurological deficits in epilepsy patients. The mechanistic basis of dendritic spine abnormalities in epilepsy has begun to be elucidated and suggests novel therapeutic strategies for treating epilepsy and its complications.
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13
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Saghyan A, LaTorre GN, Keesey R, Sharma A, Mehta V, Rudenko V, Hallas BH, Rafiuddin A, Goldstein B, Friedman LK. Glutamatergic and morphological alterations associated with early life seizure-induced preconditioning in young rats. Eur J Neurosci 2010; 32:1897-911. [DOI: 10.1111/j.1460-9568.2010.07464.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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14
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Wong M. Stabilizing dendritic structure as a novel therapeutic approach for epilepsy. Expert Rev Neurother 2008; 8:907-15. [PMID: 18505356 DOI: 10.1586/14737175.8.6.907] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
People with epilepsy often experience long-term cognitive dysfunction and other neurological deficits, including memory loss, learning disabilities and neurobehavioral disorders, which may exhibit a progressive course correlating with worsening seizure control. Furthermore, a third of epilepsy patients have seizures that are intractable to all available treatments. Thus, novel therapies for seizures and the neurological comorbidities of epilepsy are desperately needed. As most current treatments are merely symptomatic therapies that suppress seizures, epilepsy researchers have recently realized the critical need for novel therapeutic strategies targeting the underlying mechanisms of epileptogenesis and seizure-related brain injury. Yet, to date, few such antiepileptogenic therapies have emerged or are even in developmental stages. Although many seizure medications modulate the functional or physiological activity of neurons, the methods for stabilizing the structure of neurons are relatively unexplored therapeutic strategies for epilepsy. Human pathological studies and animal models of epilepsy demonstrate obvious structural abnormalities in dendrites of neurons, which could contribute to neuronal dysfunction, epileptogenesis and cognitive/neurological deficits in epilepsy patients. This dendritic injury may be caused by activity-dependent breakdown of cytoskeletal elements, such as actin. Mechanistically targeted approaches to limit seizure-related structural changes in dendrites may represent a novel therapeutic strategy for treating epilepsy and its complications.
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Affiliation(s)
- Michael Wong
- Department of Neurology, Box 8111, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
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15
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Wong M. Modulation of dendritic spines in epilepsy: cellular mechanisms and functional implications. Epilepsy Behav 2005; 7:569-77. [PMID: 16246628 DOI: 10.1016/j.yebeh.2005.08.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2005] [Revised: 08/02/2005] [Accepted: 08/07/2005] [Indexed: 01/14/2023]
Abstract
Epilepsy patients often suffer from significant neurological deficits, including memory impairment, behavioral problems, and psychiatric disorders. While the causes of neuropsychological dysfunction in epilepsy are multifactorial, accumulating evidence indicates that seizures themselves may directly cause brain injury. Although seizures sometimes result in neuronal death, they may also cause more subtle pathological changes in neuronal structure and function, including abnormalities in synaptic transmission. Dendritic spines receive a majority of the excitatory synaptic inputs to cortical neurons and are critically involved in synaptic plasticity and learning. Studies of human epilepsy and experimental animal models demonstrate that seizures may directly affect the morphological and functional properties of dendritic spines, suggesting that seizure-related changes in spines may represent a mechanistic basis for cognitive deficits in epilepsy. Novel therapeutic strategies directed at modulation of spine motility may prevent the detrimental effects of seizures on cognitive function in epilepsy.
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Affiliation(s)
- Michael Wong
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA.
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16
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Lynd-Balta E, Pilcher WH, Joseph SA. AMPA receptor alterations precede mossy fiber sprouting in young children with temporal lobe epilepsy. Neuroscience 2004; 126:105-14. [PMID: 15145077 DOI: 10.1016/j.neuroscience.2004.03.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/07/2004] [Indexed: 12/19/2022]
Abstract
Following neurological injury early in life numerous events, including excitotoxicity, neural degeneration, gliosis, neosynaptogenesis, and circuitry reorganization, may alone or in concert contribute to hyperexcitability and recurrent seizures in temporal lobe epilepsy. Our studies provide new evidence regarding the temporal sequence of key elements of hippocampal reorganization, mossy fiber sprouting and glutamate receptor subunit up-regulation, in a subset of young temporal lobe epileptic patients. Without evidence of mossy fiber sprouting, the youngest age group (3-10 years old) of mesial temporal lobe epileptic patients demonstrated enhanced glutamate receptor subunit profiles, suggesting that the dendritic change precedes axonal sprouting. However, sclerotic hippocampal specimens from epileptic patients ages 12-15 years old had the characteristic features of glutamate receptor up-regulation and mossy fiber sprouting first identified in the adult, indicating that reconstructed circuits appear early in the course of the disease. Non-sclerotic hippocampal specimens from lesion associated temporal lobe epileptic patients of all age groups showed minimal cell loss, sparse staining of glutamate receptor subunits in the dentate gyrus, and little or no mossy fiber sprouting. These compelling findings suggest a progressive sequence of events in the reorganization of the dentate gyrus of sclerotic hippocampal specimens. We suggest that cell loss and up-regulation of glutamate receptor subunits appear early in temporal lobe epilepsy and contribute to the synaptic plasticity that may facilitate the subsequent sprouting of mossy fiber collaterals which compound an already precipitous state of decline. The combination of pre-synaptic and post-synaptic changes serves as a potential substrate for hyperexcitability.
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Affiliation(s)
- E Lynd-Balta
- Department of Neurosurgery, University of Rochester Medical Center, Rochester, NY 14642, USA
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17
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Freiman TM, Gimbel K, Honegger J, Volk B, Zentner J, Frotscher M, Deller T. Anterograde tracing of human hippocampus in vitro-a neuroanatomical tract tracing technique for the analysis of local fiber tracts in human brain. J Neurosci Methods 2002; 120:95-103. [PMID: 12351210 DOI: 10.1016/s0165-0270(02)00187-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Hippocampal slices were obtained from hippocampi of patients with temporal lobe epilepsy or from patients with mass lesions located in the temporal lobe. Hippocampal slices were kept alive in a slice chamber and the anterograde tracer neurobiotin was iontophoretically injected into the granule cell layer of the dentate gyrus. Single injections resulted in the labeling of small groups of granule cells. The axonal arbor of these cells could be partially reconstructed and single mossy fibers could be followed from the soma to the inner molecular layer of the sclerotic dentate gyrus. Electron microscopy revealed asymmetric mossy fiber synapses on spiny neurons in the inner molecular layer, presumably granule cells. These data demonstrate that in vitro anterograde tracing can be employed to study the local connectivity of the human brain at the light and electron microscopic level.
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Affiliation(s)
- Thomas M Freiman
- Department of Neurosurgery, Neurozentrum, University Clinic of Freiburg, Breisacher Strasse 64, D-79106, Freiburg, Germany
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18
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Kato K, Masa T, Tawara Y, Kobayashi K, Oka T, Okabe A, Shiosaka S. Dendritic aberrations in the hippocampal granular layer and the amygdalohippocampal area following kindled-seizures. Brain Res 2001; 901:281-95. [PMID: 11368979 DOI: 10.1016/s0006-8993(01)02299-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Amygdaloid kindling is a model of human temporal lobe epilepsy, in which excitability in limbic structures is permanently enhanced by repeated stimulations. We report here dendritic aberrations occurring in mice following kindled-seizures. Adult mice received a biphasic square wave pulse [495+/-25.5 (S.E.M.) microA 60 Hz, 200 micros duration, for 2 s] unilaterally in the basolateral amygdaloid complex once a day and mice with electrophysiologically and behaviorally verified seizures were used in the experiments. The hippocampus and amygdaloid complex contralateral to the lesions were observed by immunofluorescence histochemistry with a somatodendritic marker, microtubule-associated protein 2 (MAP2), showing that kindled-seizures caused hypertrophy of proximal dendrites in the granule cells of the dentate gyrus and in neurons of the amygdalohippocampal area. To further characterize the morphological changes of the dendrites, electron micrographic analysis was performed on the contralateral side. (1) In the granular layer of the dentate gyrus and the amygdalohippocampal area, kindled-seizures generated an increase in the number of dendrites containing polymerized microtubules and width of dendritic profiles showing the increase was in the range 0.2-3.0 and 0.2-1.4 microm, respectively. (2) In the granular layer, bundles between dendrites separated by the puncta adhaerentia increased. (3) In the granular layer, the seizure-induced dendritic aberration was more severe in the rostral than the caudal region. These results suggested that growth of dendrites with enriched-stable microtubules is part of the structural plasticity in response to seizure activity in specific areas of the adult brain.
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Affiliation(s)
- K Kato
- Division of Structural Cell Biology, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama, Ikoma, 630-0101, Nara, Japan.
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19
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Okabe A, Tawara Y, Masa T, Oka T, Machida A, Tanaka T, Matsuhashi H, Shiosaka S, Kato K. Differential expression of mRNAs for sialyltransferase isoenzymes induced in the hippocampus of mouse following kindled seizures. J Neurochem 2001; 77:1185-97. [PMID: 11389169 DOI: 10.1046/j.1471-4159.2001.00319.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Sialic acids play important roles in various biological functions. In the brain, evidence suggests that sialylation of glycoproteins and glycolipids affects neural plasticity. While the 18 sialyltransferase isoenzymes (STs) identified to date synthesize individual sialyl-oligosaccharide structures, they each exhibit activity toward more than one substrate and can overlap in their specificity. Therefore, the distribution of STs is a secondary factor in the study of specific sialylation. Here, seven STs; ST3Gal I-IV, ST8Sia IV, ST6Gal I and ST6GalNAc II, the expressions of which were identified in the adult hippocampus by RT-PCR, showed diverse localization patterns in the hippocampus on in situ hybridization, suggesting that the individual cells expressed relevant STS: Furthermore, to assay activity-related changes in ST expression, we used amygdaloid-kindling among models of neural plasticity. Differential expression of the STs participating in the kindling, notably, up-regulation of ST3Gal IV and ST6GalNAc II mRNAs, and down-regulation of ST3Gal I and ST8Sia IV mRNAs, were observed in the hippocampus following kindled seizures. These results indicate that ST expressions are regulated by physiological activity and may play a role in neural plasticity.
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Affiliation(s)
- A Okabe
- Division of Structural Cell Biology, Nara Institute of Science and Technology, Nara, Japan
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20
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Abstract
Studies of neurons from human epilepsy tissue and comparable animal models of focal epilepsy have consistently reported a marked decrease in dendritic spine density on hippocampal and neocortical pyramidal cells. Spine loss is often accompanied by focal varicose swellings or beading of dendritic segments. An ongoing excitotoxic injury of dendrites (dendrotoxicity), produced by excessive release of glutamate during seizures, is often assumed to produce these abnormalities. Indeed, application of glutamate receptor agonists to dendrites can produce both spine loss and beading. However, the cellular mechanisms underlying the two processes appear to be different. One recent study suggests NMDA-induced spine loss is produced by Ca2+-mediated alterations of the spine cytoskeleton. In contrast, dendritic beading is not dependent on extracellular Ca2+; instead, it appears to be produced by the movement of Na+ and Cl- intracellularly and an obligate movement of water to maintain osmolarity. A decrease in dendritic spine density was recently reported in a model of recurrent focal seizures in early life. Unlike results from other models, dendritic beading was not observed, and other signs of neuronal injury and death were absent. Thus, additional mechanisms to those of excitotoxicity may produce dendritic spine loss in epileptic tissue. A hypothesis is presented that spine loss can be a product of a partial deafferentation of pyramidal cells, resulting from an activity-dependent pruning of neuronal connectivity induced by recurring seizures. The dendritic abnormalities observed in epilepsy are commonly suggested to be a product and not a cause of epilepsy. However, anatomical remodeling may be accompanied by alterations in molecular expression and targeting of both voltage- and ligand-gated channels in dendrites. It is conceivable that such changes could contribute to the neuronal hyperexcitability of epilepsy.
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Affiliation(s)
- J W Swann
- Cain Foundation Laboratories, Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA.
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21
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Ribak CE, Tran PH, Spigelman I, Okazaki MM, Nadler JV. Status epilepticus-induced hilar basal dendrites on rodent granule cells contribute to recurrent excitatory circuitry. J Comp Neurol 2000; 428:240-53. [PMID: 11064364 DOI: 10.1002/1096-9861(20001211)428:2<240::aid-cne4>3.0.co;2-q] [Citation(s) in RCA: 195] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Mossy fiber sprouting into the inner molecular layer of the dentate gyrus is an important neuroplastic change found in animal models of temporal lobe epilepsy and in humans with this type of epilepsy. Recently, we reported in the perforant path stimulation model another neuroplastic change for dentate granule cells following seizures: hilar basal dendrites (HBDs). The present study determined whether status epilepticus-induced HBDs on dentate granule cells occur in the pilocarpine model of temporal lobe epilepsy and whether these dendrites are targeted by mossy fibers. Retrograde transport of biocytin following its ejection into stratum lucidum of CA3 was used to label granule cells for both light and electron microscopy. Granule cells with a heterogeneous morphology, including recurrent basal dendrites, and locations outside the granule cell layer were observed in control preparations. Preparations from both pilocarpine and kainate models of temporal lobe epilepsy also showed granule cells with HBDs. These dendrites branched and extended into the hilus of the dentate gyrus and were shown to be present on 5% of the granule cells in pilocarpine-treated rats with status epilepticus, whereas control rats had virtually none. Electron microscopy was used to determine whether HBDs were postsynaptic to axon terminals in the hilus, a site where mossy fiber collaterals are prevalent. Labeled granule cell axon terminals were found to form asymmetric synapses with labeled HBDs. Also, unlabeled, large mossy fiber boutons were presynaptic to HBDs of granule cells. These results indicate that HBDs are present in the pilocarpine model of temporal lobe epilepsy, confirm the presence of HBDs in the kainate model, and show that HBDs are postsynaptic to mossy fibers. These new mossy fiber synapses with HBDs may contribute to additional recurrent excitatory circuitry for granule cells.
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Affiliation(s)
- C E Ribak
- Department of Anatomy and Neurobiology, University of California at Irvine, College of Medicine, Irvine, California 92697-1275, USA.
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22
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Isokawa M. Remodeling dendritic spines of dentate granule cells in temporal lobe epilepsy patients and the rat pilocarpine model. Epilepsia 2000; 41 Suppl 6:S14-7. [PMID: 10999513 DOI: 10.1111/j.1528-1157.2000.tb01550.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To study when dendritic alteration can occur in the epileptic hippocampus and how it is influenced by epileptic axonal reorganization. METHODS Human specimens and the rat pilocarpine model were used. Dentate granule cells (DGCs) were visualized by intracellular biocytin injection for spine count. RESULTS In the rat pilocarpine model, dendrites of DGCs revealed a generalized spine loss immediately after the acute status epilepticus induced by pilocarpine. However, this generalized damage was transient and was followed by recovery and plastic changes in spine shape and density, which occurred 15 to 35 days after the initial acute status, i.e., during the period of establishing a chronic phase of this model with the induction of spontaneous seizures. In human epileptic hippocampi, spine density was significantly higher when DGCs generated aberrant mossy fiber collaterals. This was particularly so in the proximal dendrite of DGCs, where the aberrant collaterals were densely localized. These findings suggest that initial acute seizures do not cause permanent damage in dendrites and spines of DGCs and that dendritic spines of epileptic neurons can respond to changes in the local cellular environment, including newly formed afferents, in a plastic manner. CONCLUSION Dendritic spines are dynamically maintained in chronic epilepsy during the course of establishment and maintenance of spontaneous seizures. Local dendritic spine alteration, detected later in the chronic phase of epilepsy, must have a separate cause from initial acute insults.
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Affiliation(s)
- M Isokawa
- Department of Neurology, Reed Neurological Research Center, University of California, Los Angeles 90095-1769, USA.
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23
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Abstract
Neuronal mechanisms underlying focal convulsions and secondary generalised convulsions have been extensively investigated at many different levels, from the biochemical, through the cellular to the intact brain. Numerous pathogenic processes relevant to epilepsy are now known. Experimental models suggest that alterations to the shape, connectivity and receptor-chemistry of individual neurons increase their excitability and the resultant increases in activity lead to changes of the local ionic environment that further causes enhanced excitability. As a consequence of the latter, neuronal firing rates increase and there is a shift from single-firing- to burst-firing-behaviours in populations of neurons and, possibly, also several changes in the way populations of neurons communicate, namely, from 'synaptic' to 'electric' and from orthodromic to antidromic. As a consequence, massive neuronal synchronisation occurs, the correlate of the focal or secondarily generalised attack. Because of experimental difficulties in studying the widespread and evolving neuronal activities in freely behaving animals, a precise correlation between states of neuronal activation and convulsive behaviour is still unclear.
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Affiliation(s)
- J O Willoughby
- Centre for Neuroscience and Department of Medicine, Flinders University and Medical Centre, Adelaide, South Australia
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24
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Williamson A, Patrylo PR, Spencer DD. Decrease in inhibition in dentate granule cells from patients with medial temporal lobe epilepsy. Ann Neurol 1999; 45:92-9. [PMID: 9894882 DOI: 10.1002/1531-8249(199901)45:1<92::aid-art15>3.0.co;2-n] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Alterations in synaptic inhibition are associated with epileptiform activity in several acute animal models; however, it is not clear if there are changes in inhibition in chronically epileptic tissue. We have used intracellular recordings from granule cells of patients with temporal lobe epilepsy to determine whether synaptic inhibition is compromised. Two groups of patients with medial temporal lobe epilepsy were used, those with medial temporal lobe sclerosis (MTLE), and those with extrahippocampal masses (MaTLE) where the cell loss and synaptic reorganization that characterize MTLE are not seen. Although the level of tonic inhibition at the somata was not significantly different in the two patient groups, there was a reduction in the conductance of polysynaptic perforant path-evoked fast and slow inhibitory postsynaptic potentials (IPSPs) (53% and 66%, respectively). We found that there was a comparable decrease in the monosynaptic IPSP conductances examined in the presence of glutamatergic antagonists as that seen for the polysynaptically evoked IPSPs. These data suggest that the decrease in inhibition seen in normal artificial cerebrospinal fluid in MTLE granule cells cannot be solely explained by a decrease in excitatory input onto inhibitory interneurons and may reflect changes at the interneuron-granule cells synapse or in the number of specific inhibitory interneurons.
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Affiliation(s)
- A Williamson
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT 06520-8082, USA
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Spigelman I, Yan XX, Obenaus A, Lee EY, Wasterlain CG, Ribak CE. Dentate granule cells form novel basal dendrites in a rat model of temporal lobe epilepsy. Neuroscience 1998; 86:109-20. [PMID: 9692747 DOI: 10.1016/s0306-4522(98)00028-1] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mossy fibre sprouting and re-organization in the inner molecular layer of the dentate gyrus is a characteristic of many models of temporal lobe epilepsy including that induced by perforant-path stimulation. However, neuroplastic changes on the dendrites of granule cells have been less-well studied. Basal dendrites are a transient morphological feature of rodent granule cells during development. The goal of the present study was to examine whether granule cell basal dendrites are generated in rats with epilepsy induced by perforant-path stimulation. Adult Wistar rats were stimulated for 24 h at 2 Hz and with intermittent (1/min) trains (10 s duration) of single stimuli at 20 Hz (20 V, 0.1 ms) delivered 1/min via an electrode placed in the angular bundle. The brains of these experimental rats and age- and litter-matched control animals were processed for the rapid Golgi method. All rats with perforant-path stimulation displayed basal dendrites on many Golgi-impregnated granule cells. These basal dendrites mainly originated from their somata at the hilar side and then extended into the hilus. Quantitative analysis of more than 800 granule cells in the experimental and matched control brains showed that 6-15% (mean=8.7%) of the impregnated granule cells have spiny basal dendrites on the stimulated side, as well as the contralateral side (mean=3.1%, range=2.9-3.9%) of experimental rats, whereas no basal dendrites were observed in the dentate gyrus from control animals. The formation of basal dendrites appears to be an adaptive morphological change for granule cells in addition to the previously described mossy fibre sprouting, as well as dendritic and somatic spine formation observed in the dentate gyrus of animal and human epileptic brains. The presence of these dendrites in the subgranular region of the hilus suggests that they may be postsynaptic targets of the mossy fibre collaterals.
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Affiliation(s)
- I Spigelman
- Section of Oral Biology, UCLA School of Dentistry, Los Angeles, CA 90095-1668, USA
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