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Jablonski J, Hoffmann L, Blümcke I, Fejtová A, Uebe S, Ekici AB, Gnatkovsky V, Kobow K. Experimental Epileptogenesis in a Cell Culture Model of Primary Neurons from Rat Brain: A Temporal Multi-Scale Study. Cells 2021; 10:cells10113004. [PMID: 34831225 PMCID: PMC8616120 DOI: 10.3390/cells10113004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 10/27/2021] [Accepted: 11/02/2021] [Indexed: 12/24/2022] Open
Abstract
Understanding seizure development requires an integrated knowledge of different scales of organization of epileptic networks. We developed a model of “epilepsy-in-a-dish” based on dissociated primary neuronal cells from neonatal rat hippocampus. We demonstrate how a single application of glutamate stimulated neurons to generate spontaneous synchronous spiking activity with further progression into spontaneous seizure-like events after a distinct latency period. By computational analysis, we compared the observed neuronal activity in vitro with intracranial electroencephalography (EEG) data recorded from epilepsy patients and identified strong similarities, including a related sequence of events with defined onset, progression, and termination. Next, a link between the neurophysiological changes with network composition and cellular structure down to molecular changes was established. Temporal development of epileptiform network activity correlated with increased neurite outgrowth and altered branching, increased ratio of glutamatergic over GABAergic synapses, and loss of calbindin-positive interneurons, as well as genome-wide alterations in DNA methylation. Differentially methylated genes were engaged in various cellular activities related to cellular structure, intracellular signaling, and regulation of gene expression. Our data provide evidence that a single short-term excess of glutamate is sufficient to induce a cascade of events covering different scales from molecule- to network-level, all of which jointly contribute to seizure development.
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Affiliation(s)
- Janos Jablonski
- Department of Neuropathology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (J.J.); (L.H.); (I.B.)
| | - Lucas Hoffmann
- Department of Neuropathology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (J.J.); (L.H.); (I.B.)
| | - Ingmar Blümcke
- Department of Neuropathology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (J.J.); (L.H.); (I.B.)
| | - Anna Fejtová
- Department of Psychiatry and Psychotherapy, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany;
| | - Steffen Uebe
- NGS Core Unit, Institute of Human Genetics, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.U.); (A.B.E.)
| | - Arif B. Ekici
- NGS Core Unit, Institute of Human Genetics, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.U.); (A.B.E.)
| | - Vadym Gnatkovsky
- Department of Epileptology, University Hospital Bonn, 53127 Bonn, Germany;
| | - Katja Kobow
- Department of Neuropathology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (J.J.); (L.H.); (I.B.)
- Correspondence: ; Tel.: +49-9131-8522859
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Garner R, La Rocca M, Vespa P, Jones N, Monti MM, Toga AW, Duncan D. Imaging biomarkers of posttraumatic epileptogenesis. Epilepsia 2019; 60:2151-2162. [PMID: 31595501 PMCID: PMC6842410 DOI: 10.1111/epi.16357] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 09/10/2019] [Accepted: 09/10/2019] [Indexed: 12/14/2022]
Abstract
Traumatic brain injury (TBI) affects 2.5 million people annually within the United States alone, with over 300 000 severe injuries resulting in emergency room visits and hospital admissions. Severe TBI can result in long-term disability. Posttraumatic epilepsy (PTE) is one of the most debilitating consequences of TBI, with an estimated incidence that ranges from 2% to 50% based on severity of injury. Conducting studies of PTE poses many challenges, because many subjects with TBI never develop epilepsy, and it can be more than 10 years after TBI before seizures begin. One of the unmet needs in the study of PTE is an accurate biomarker of epileptogenesis, or a panel of biomarkers, which could provide early insights into which TBI patients are most susceptible to PTE, providing an opportunity for prophylactic anticonvulsant therapy and enabling more efficient large-scale PTE studies. Several recent reviews have provided a comprehensive overview of this subject (Neurobiol Dis, 123, 2019, 3; Neurotherapeutics, 11, 2014, 231). In this review, we describe acute and chronic imaging methods that detect biomarkers for PTE and potential mechanisms of epileptogenesis. We also describe shortcomings in current acquisition methods, analysis, and interpretation that limit ongoing investigations that may be mitigated with advancements in imaging techniques and analysis.
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Affiliation(s)
- Rachael Garner
- Laboratory of Neuro Imaging, USC Stevens Neuroimaging and Informatics Institute, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States
| | - Marianna La Rocca
- Laboratory of Neuro Imaging, USC Stevens Neuroimaging and Informatics Institute, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States
| | - Paul Vespa
- Division of Neurosurgery, Department of Neurology, University of California Los Angeles School of Medicine, Los Angeles, CA, United States
| | - Nigel Jones
- Van Cleef Centre for Nervous Diseases, Department of Neuroscience, Monash University, Clayton, VIC, Australia
| | - Martin M. Monti
- Department of Psychology, University of California Los Angeles, Los Angeles, CA, United States
| | - Arthur W. Toga
- Laboratory of Neuro Imaging, USC Stevens Neuroimaging and Informatics Institute, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States
| | - Dominique Duncan
- Laboratory of Neuro Imaging, USC Stevens Neuroimaging and Informatics Institute, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States
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Perucca P, Smith G, Santana-Gomez C, Bragin A, Staba R. Electrophysiological biomarkers of epileptogenicity after traumatic brain injury. Neurobiol Dis 2018; 123:69-74. [PMID: 29883622 DOI: 10.1016/j.nbd.2018.06.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Revised: 05/30/2018] [Accepted: 06/03/2018] [Indexed: 02/08/2023] Open
Abstract
Post-traumatic epilepsy is the architype of acquired epilepsies, wherein a brain insult initiates an epileptogenic process culminating in an unprovoked seizure after weeks, months or years. Identifying biomarkers of such process is a prerequisite for developing and implementing targeted therapies aimed at preventing the development of epilepsy. Currently, there are no validated electrophysiological biomarkers of post-traumatic epileptogenesis. Experimental EEG studies using the lateral fluid percussion injury model have identified three candidate biomarkers of post-traumatic epileptogenesis: pathological high-frequency oscillations (HFOs, 80-300 Hz); repetitive HFOs and spikes (rHFOSs); and reduction in sleep spindle duration and dominant frequency at the transition from stage III to rapid eye movement sleep. EEG studies in humans have yielded conflicting data; recent evidence suggests that epileptiform abnormalities detected acutely after traumatic brain injury carry a significantly increased risk of subsequent epilepsy. Well-designed studies are required to validate these promising findings, and ultimately establish whether there are post-traumatic electrophysiological features which can guide the development of 'antiepileptogenic' therapies.
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Affiliation(s)
- Piero Perucca
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia; Department of Neurology, The Royal Melbourne Hospital, Melbourne, VIC, Australia; Department of Neurology, Alfred Health, Melbourne, VIC, Australia; Melbourne Medical School, The University of Melbourne, Melbourne, VIC, Australia.
| | - Gregory Smith
- Department of Neurosurgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Cesar Santana-Gomez
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Anatol Bragin
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Richard Staba
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
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Wang W, Zinsmaier AK, Firestone E, Lin R, Yatskievych TA, Yang S, Zhang J, Bao S. Blocking Tumor Necrosis Factor-Alpha Expression Prevents Blast-Induced Excitatory/Inhibitory Synaptic Imbalance and Parvalbumin-Positive Interneuron Loss in the Hippocampus. J Neurotrauma 2018; 35:2306-2316. [PMID: 29649942 DOI: 10.1089/neu.2018.5688] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Traumatic brain injury (TBI) is a major cause of neurological disorder and death in civilian and military populations. It comprises two components-direct injury from the traumatic impact and secondary injury from ensuing neural inflammatory responses. Blocking tumor necrosis factor-alpha (TNF-α), a central regulator of neural inflammation, has been shown to improve functional recovery after TBI. However, the mechanisms underlying those therapeutic effects are still poorly understood. Here, we examined effects of 3,6'-dithiothalidomide (dTT), a potentially therapeutic TNF-α inhibitor, in mice with blast-induced TBI. We found that blast exposure resulted in elevated expression of TNF-α, activation of microglial cells, enhanced excitatory synaptic transmission, reduced inhibitory synaptic transmission, and a loss of parvalbumin-positive (PV+) inhibitory interneurons. Administration of dTT for 5 days after the blast exposure completely suppressed blast-induced increases in TNF-α transcription, largely reversed blasted-induced synaptic changes, and prevented PV+ neuron loss. However, blocking TNF-α expression by dTT failed to mitigate blast-induced microglial activation in the hippocampus, as evidenced by their non-ramified morphology. These results indicate that TNF-α plays a major role in modulating neuronal functions in blast-induced TBI and that it is a potential target for treatment of TBI-related brain disorders.
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Affiliation(s)
- Weihua Wang
- 1 Department of Physiology, College of Medicine, University of Arizona , Tucson, Arizona
| | - Alexander K Zinsmaier
- 1 Department of Physiology, College of Medicine, University of Arizona , Tucson, Arizona
| | - Ethan Firestone
- 2 Department of Otolaryngology-Head and Neck Surgery and Department of Communication Sciences and Disorders, School of Medicine, Wayne State University , Detroit, Michigan
| | - Ruizhu Lin
- 1 Department of Physiology, College of Medicine, University of Arizona , Tucson, Arizona.,3 Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University , Guangzhou, China
| | - Tatiana A Yatskievych
- 1 Department of Physiology, College of Medicine, University of Arizona , Tucson, Arizona
| | - Sungchil Yang
- 4 Department of Biomedical Sciences, City University of Hong Kong , Kowloon, Hong Kong, China
| | - Jinsheng Zhang
- 2 Department of Otolaryngology-Head and Neck Surgery and Department of Communication Sciences and Disorders, School of Medicine, Wayne State University , Detroit, Michigan
| | - Shaowen Bao
- 1 Department of Physiology, College of Medicine, University of Arizona , Tucson, Arizona
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Nirwan N, Vyas P, Vohora D. Animal models of status epilepticus and temporal lobe epilepsy: a narrative review. Rev Neurosci 2018; 29:757-770. [DOI: 10.1515/revneuro-2017-0086] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 01/26/2018] [Indexed: 11/15/2022]
Abstract
Abstract
Temporal lobe epilepsy (TLE) is the chronic and pharmacoresistant form of epilepsy observed in humans. The current literature is insufficient in explicating the comprehensive mechanisms underlying its pathogenesis and advancement. Consequently, the development of a suitable animal model mimicking the clinical characteristics is required. Further, the relevance of status epilepticus (SE) to animal models is dubious. SE occurs rarely in people; most epilepsy patients never experience it. The present review summarizes the established animal models of SE and TLE, along with a brief discussion of the animal models that have the distinctiveness and carries the possibility to be developed as effective models for TLE. The review not only covers the basic requirements, mechanisms, and methods of induction of each model but also focuses upon their major limitations and possible modifications for their future use. A detailed discussion on chemical, electrical, and hypoxic/ischemic models as well as a brief explanation on the genetic models, most of which are characterized by development of SE followed by neurodegeneration, is presented.
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Affiliation(s)
- Nikita Nirwan
- Neurobehavioral Pharmacology Laboratory , Department of Pharmacology , School of Pharmaceutical Education and Research, Jamia Hamdard , New Delhi 110062 , India
| | - Preeti Vyas
- Neurobehavioral Pharmacology Laboratory , Department of Pharmacology , School of Pharmaceutical Education and Research, Jamia Hamdard , New Delhi 110062 , India
| | - Divya Vohora
- Neurobehavioral Pharmacology Laboratory , Department of Pharmacology , School of Pharmaceutical Education and Research, Jamia Hamdard , New Delhi 110062 , India
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Zhang BL, Fan YS, Wang JW, Zhou ZW, Wu YG, Yang MC, Sun DD, Zhang JN. Cognitive impairment after traumatic brain injury is associated with reduced long-term depression of excitatory postsynaptic potential in the rat hippocampal dentate gyrus. Neural Regen Res 2018; 13:1753-1758. [PMID: 30136690 PMCID: PMC6128047 DOI: 10.4103/1673-5374.238618] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Traumatic brain injury can cause loss of neuronal tissue, remote symptomatic epilepsy, and cognitive deficits. However, the mechanisms underlying the effects of traumatic brain injury are not yet clear. Hippocampal excitability is strongly correlated with cognitive dysfunction and remote symptomatic epilepsy. In this study, we examined the relationship between traumatic brain injury-induced neuronal loss and subsequent hippocampal regional excitability. We used hydraulic percussion to generate a rat model of traumatic brain injury. At 7 days after injury, the mean modified neurological severity score was 9.5, suggesting that the neurological function of the rats was remarkably impaired. Electrophysiology and immunocytochemical staining revealed increases in the slope of excitatory postsynaptic potentials and long-term depression (indicating weakened long-term inhibition), and the numbers of cholecystokinin and parvalbumin immunoreactive cells were clearly reduced in the rat hippocampal dentate gyrus. These results indicate that interneuronal loss and changes in excitability occurred in the hippocampal dentate gyrus. Thus, traumatic brain injury-induced loss of interneurons appears to be associated with reduced long-term depression in the hippocampal dentate gyrus.
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Affiliation(s)
- Bao-Liang Zhang
- Department of Neurosurgery, Tianjin Medical University General Hospital; Tianjin Neurological Institute; Key Laboratory of Post-trauma Neuro-repair and Regeneration in Central Nervous System, Ministry of Education; Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin, China
| | - Yue-Shan Fan
- Department of Neurosurgery, Tianjin Medical University General Hospital; Tianjin Neurological Institute; Key Laboratory of Post-trauma Neuro-repair and Regeneration in Central Nervous System, Ministry of Education; Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin, China
| | - Ji-Wei Wang
- Department of Neurosurgery, Tianjin Medical University General Hospital; Tianjin Neurological Institute; Key Laboratory of Post-trauma Neuro-repair and Regeneration in Central Nervous System, Ministry of Education; Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin, China
| | - Zi-Wei Zhou
- Department of Neurosurgery, Tianjin Medical University General Hospital; Tianjin Neurological Institute; Key Laboratory of Post-trauma Neuro-repair and Regeneration in Central Nervous System, Ministry of Education; Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin, China
| | - Yin-Gang Wu
- Department of Neurosurgery, Tianjin Medical University General Hospital; Tianjin Neurological Institute; Key Laboratory of Post-trauma Neuro-repair and Regeneration in Central Nervous System, Ministry of Education; Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin, China
| | - Meng-Chen Yang
- Department of Neurosurgery, Tianjin Medical University General Hospital; Tianjin Neurological Institute; Key Laboratory of Post-trauma Neuro-repair and Regeneration in Central Nervous System, Ministry of Education; Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin, China
| | - Dong-Dong Sun
- Department of Neurosurgery, Tianjin Medical University General Hospital; Tianjin Neurological Institute; Key Laboratory of Post-trauma Neuro-repair and Regeneration in Central Nervous System, Ministry of Education; Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin, China
| | - Jian-Ning Zhang
- Department of Neurosurgery, Tianjin Medical University General Hospital; Tianjin Neurological Institute; Key Laboratory of Post-trauma Neuro-repair and Regeneration in Central Nervous System, Ministry of Education; Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin, China
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Liu J, Saponjian Y, Mahoney MM, Staley KJ, Berdichevsky Y. Epileptogenesis in organotypic hippocampal cultures has limited dependence on culture medium composition. PLoS One 2017; 12:e0172677. [PMID: 28225808 PMCID: PMC5321418 DOI: 10.1371/journal.pone.0172677] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 02/08/2017] [Indexed: 01/10/2023] Open
Abstract
Rodent organotypic hippocampal cultures spontaneously develop epileptiform activity after approximately 2 weeks in vitro and are increasingly used as a model of chronic post-traumatic epilepsy. However, organotypic cultures are maintained in an artificial environment (culture medium), which contains electrolytes, glucose, amino acids and other components that are not present at the same concentrations in cerebrospinal fluid (CSF). Therefore, it is possible that epileptogenesis in organotypic cultures is driven by these components. We examined the influence of medium composition on epileptogenesis. Epileptogenesis was evaluated by measurements of lactate and lactate dehydrogenase (LDH) levels (biomarkers of ictal activity and cell death, respectively) in spent culture media, immunohistochemistry and automated 3-D cell counts, and extracellular recordings from CA3 regions. Changes in culture medium components moderately influenced lactate and LDH levels as well as electrographic seizure burden and cell death. However, epileptogenesis occurred in any culture medium that was capable of supporting neural survival. We conclude that medium composition is unlikely to be the cause of epileptogenesis in the organotypic hippocampal culture model of chronic post-traumatic epilepsy.
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Affiliation(s)
- Jing Liu
- Department of Electrical and Computer Engineering, Lehigh University, Bethlehem, Pennsylvania, United States of America
| | - Yero Saponjian
- Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Harvard Medical School, Boston, Massachusetts, United States of America
| | - Mark M. Mahoney
- Bioengineering Program, Lehigh University, Bethlehem, Pennsylvania, United States of America
| | - Kevin J. Staley
- Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Harvard Medical School, Boston, Massachusetts, United States of America
| | - Yevgeny Berdichevsky
- Department of Electrical and Computer Engineering, Lehigh University, Bethlehem, Pennsylvania, United States of America
- Bioengineering Program, Lehigh University, Bethlehem, Pennsylvania, United States of America
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Abstract
The epileptic encephalopathies are severe and often treatment-resistant conditions that are associated with a progressive disturbance of brain function, resulting in a broad range of neurological and non-neurological comorbidities. The concept of epileptic encephalopathies entails that the encephalopathy aspect of the overall condition is primarily driven by the epileptic activity of the disease, which often manifests as specific and pathological features on the electroencephalogram. Genetic factors in epileptic encephalopathies are increasingly recognized. As of 2016, more than 30 genes have been securely implicated as causative genes for genetic epileptic encephalopathies. Even though the traditional concept of epileptic encephalopathies entails that the progressive disturbance of brain dysfunction is primarily due to the abnormal hypersynchronous activity that underlies the seizure disorders, this strict concept rarely holds true for patients with identified genetic etiologies. More commonly, an underlying genetic etiology is thought to predispose both to the neurodevelopmental comorbidities and to the seizure phenotype with a complex interaction between both. In this chapter, we will elucidate to what extent neurodegeneration rather than epilepsy-related regression is a feature of the common epileptic encephalopathies, drawing parallels between two relatively separate fields of neurogenetic research.
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Global Outcome and Late Seizures After Penetrating Versus Closed Traumatic Brain Injury: A NIDRR TBI Model Systems Study. J Head Trauma Rehabil 2016; 30:231-40. [PMID: 25931183 DOI: 10.1097/htr.0000000000000127] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND If and how much dural penetration influences long-term outcome after traumatic brain injury (TBI) is understudied, especially within the civilian population. OBJECTIVES Using the large TBI Model Systems cohort, this study assessed and compared penetrating TBI (PTBI) and closed TBI with respect to global outcome and late seizures 2 years after injury. METHODS After performing unadjusted PTBI versus closed TBI comparisons, multivariate regression models were built and analyzed for both outcomes by including the following additional predictors: length of unconsciousness, posttraumatic amnesia duration, hospital length of stay, age, gender, race, marital status, education level, problem substance abuse, and preinjury employment status. RESULTS The collapsed Glasgow Outcome Scale model (n = 6111) showed significant secondary effects of PTBI with employment status. When employed before injury, individuals with PTBI were 2.62 times more likely (95% confidence interval, 1.92-3.57) to have a lower Glasgow Outcome Scale category. The final model for late seizures (n = 6737) showed a significant main effect for PTBI. Adjusting for other predictors, individuals with PTBI were 2.78 times more likely (95% confidence interval, 1.93-3.99) than those with closed TBI to be rehospitalized for a seizure. CONCLUSION This study empirically demonstrates that penetrating injury mechanism has important prognostic implications.
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Abstract
Posttraumatic epilepsy (PTE) is one of the most common and devastating complications of traumatic brain injury (TBI). Currently, the etiopathology and mechanisms of PTE are poorly understood and as a result, there is no effective treatment or means to prevent it. Antiepileptic drugs remain common preventive strategies in the management of TBI to control acute posttraumatic seizures and to prevent the development of PTE, although their efficacy in the latter case is disputed. Different strategies of PTE prophylaxis have been showing promise in preclinical models, but their translation to the clinic still remains elusive due in part to the variability of these models and the fact they do not recapitulate all complex pathologies associated with human TBI. TBI is a multifaceted disorder reflected in several potentially epileptogenic alterations in the brain, including mechanical neuronal and vascular damage, parenchymal and subarachnoid hemorrhage, subsequent toxicity caused by iron-rich hemoglobin breakdown products, and energy disruption resulting in secondary injuries, including excitotoxicity, gliosis, and neuroinflammation, often coexisting to a different degree. Several in vivo models have been developed to reproduce the acute TBI cascade of events, to reflect its anatomical pathologies, and to replicate neurological deficits. Although acute and chronic recurrent posttraumatic seizures are well-recognized phenomena in these models, there is only a limited number of studies focused on PTE. The most used mechanical TBI models with documented electroencephalographic and behavioral seizures with remote epileptogenesis include fluid percussion, controlled cortical impact, and weight-drop. This chapter describes the most popular models of PTE-induced TBI models, focusing on the controlled cortical impact and the fluid percussion injury models, the methods of behavioral and electroencephalogram seizure assessments, and other approaches to detect epileptogenic properties, and discusses their potential application for translational research.
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Schmitt S, Dichter MA. Electrophysiologic recordings in traumatic brain injury. HANDBOOK OF CLINICAL NEUROLOGY 2015; 127:319-339. [PMID: 25702226 DOI: 10.1016/b978-0-444-52892-6.00021-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Following a traumatic brain injury (TBI), the brain undergoes numerous electrophysiologic changes. The most common techniques used to evaluate these changes include electroencepalography (EEG) and evoked potentials. In animals, EEGs immediately following TBI can show either diffuse slowing or voltage attenuation, or high voltage spiking. Following a TBI, many animals display evidence of hippocampal excitability and a reduced seizure threshold. Some mice subjected to severe TBI via a fluid percussion injury will eventually develop seizures, which provides a useful potential model for studying the neurophysiology of epileptogenesis. In humans, the EEG changes associated with mild TBI are relatively subtle and may be challenging to distinguish from EEG changes seen in other conditions. Quantitative EEG (QEEG) may enhance the ability to detect post-traumatic electrophysiologic changes following a mild TBI. Some types of evoked potential (EP) and event related potential (ERP) can also be used to detect post-traumatic changes following a mild TBI. Continuous EEG monitoring (cEEG) following moderate and severe TBI is useful in detecting the presence of seizures and status epilepticus acutely following an injury, although some seizures may only be detectable using intracranial monitoring. CEEG can also be helpful for assessing prognosis after moderate or severe TBI. EPs, particularly somatosensory evoked potentials, can also be useful in assessing prognosis following severe TBI. The role for newer technologies such as magnetoencephalography and bispectral analysis (BIS) in the evaluation of patients with TBI remains unclear.
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Affiliation(s)
- Sarah Schmitt
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA
| | - Marc A Dichter
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA.
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Lyon AP, Wainman D, Marone S, Weaver DF. A Spontaneous Recurrent Seizure Bioassay for Anti-Epileptogenic Molecules. Can J Neurol Sci 2014; 32:97-102. [PMID: 15825554 DOI: 10.1017/s0317167100016954] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Drug design in epilepsy is now tackling a new target - epileptogenesis. This is the process whereby a normal brain becomes susceptible to recurrent seizures. One of the stumbling blocks in the design and discovery of new chemical entities as antiepileptogenics is the implementation of an appropriate biological model. Current models, such as the maximal electroshock model, are models of seizures, not models of epileptogenesis. To develop such a model, we have extended and modified a chronic pilocarpine spontaneous recurrent seizure (SRS) model for the purposes of developing a bioassay with which to screen new compounds for putative antiepileptogenic bioactivity.
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Affiliation(s)
- Angela P Lyon
- Department of Chemistry, Queen's University, Kingston, Ontario, Canada
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13
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Szaflarski JP, Nazzal Y, Dreer LE. Post-traumatic epilepsy: current and emerging treatment options. Neuropsychiatr Dis Treat 2014; 10:1469-77. [PMID: 25143737 PMCID: PMC4136984 DOI: 10.2147/ndt.s50421] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Traumatic brain injury (TBI) leads to many undesired problems and complications, including immediate and long-term seizures/epilepsy, changes in mood, behavioral, and personality problems, cognitive and motor deficits, movement disorders, and sleep problems. Clinicians involved in the treatment of patients with acute TBI need to be aware of a number of issues, including the incidence and prevalence of early seizures and post-traumatic epilepsy (PTE), comorbidities associated with seizures and anticonvulsant therapies, and factors that can contribute to their emergence. While strong scientific evidence for early seizure prevention in TBI is available for phenytoin (PHT), other antiepileptic medications, eg, levetiracetam (LEV), are also being utilized in clinical settings. The use of PHT has its drawbacks, including cognitive side effects and effects on function recovery. Rates of recovery after TBI are expected to plateau after a certain period of time. Nevertheless, some patients continue to improve while others deteriorate without any clear contributing factors. Thus, one must ask, 'Are there any actions that can be taken to decrease the chance of post-traumatic seizures and epilepsy while minimizing potential short- and long-term effects of anticonvulsants?' While the answer is 'probably,' more evidence is needed to replace PHT with LEV on a permanent basis. Some have proposed studies to address this issue, while others look toward different options, including other anticonvulsants (eg, perampanel or other AMPA antagonists), or less established treatments (eg, ketamine). In this review, we focus on a comparison of the use of PHT versus LEV in the acute TBI setting and summarize the clinical aspects of seizure prevention in humans with appropriate, but general, references to the animal literature.
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Affiliation(s)
- Jerzy P Szaflarski
- Department of Neurology, University of Alabama at Birmingham, Birmingham, AL, USA ; UAB Epilepsy Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Yara Nazzal
- Department of Neurology, University of Alabama at Birmingham, Birmingham, AL, USA ; UAB Epilepsy Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Laura E Dreer
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, AL, USA
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Grohmann KS, Schmidt MJ, Moritz A, Kramer M. Prevalence of seizures in cats after head trauma. J Am Vet Med Assoc 2012; 241:1467-70. [DOI: 10.2460/javma.241.11.1467] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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15
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Gurkoff GG, Shahlaie K, Lyeth BG. In vitro mechanical strain trauma alters neuronal calcium responses: Implications for posttraumatic epilepsy. Epilepsia 2012; 53 Suppl 1:53-60. [DOI: 10.1111/j.1528-1167.2012.03475.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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16
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Decrease in tonic inhibition contributes to increase in dentate semilunar granule cell excitability after brain injury. J Neurosci 2012; 32:2523-37. [PMID: 22396425 DOI: 10.1523/jneurosci.4141-11.2012] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Brain injury is an etiological factor for temporal lobe epilepsy and can lead to memory and cognitive impairments. A recently characterized excitatory neuronal class in the dentate molecular layer, semilunar granule cell (SGC), has been proposed to regulate dentate network activity patterns and working memory formation. Although SGCs, like granule cells, project to CA3, their typical sustained firing and associational axon collaterals suggest that they are functionally distinct from granule cells. We find that brain injury results in an enhancement of SGC excitability associated with an increase in input resistance 1 week after trauma. In addition to prolonging miniature and spontaneous IPSC interevent intervals, brain injury significantly reduces the amplitude of tonic GABA currents in SGCs. The postinjury decrease in SGC tonic GABA currents is in direct contrast to the increase observed in granule cells after trauma. Although our observation that SGCs express Prox1 indicates a shared lineage with granule cells, data from control rats show that SGC tonic GABA currents are larger and sIPSC interevent intervals shorter than in granule cells, demonstrating inherent differences in inhibition between these cell types. GABA(A) receptor antagonists selectively augmented SGC input resistance in controls but not in head-injured rats. Moreover, post-traumatic differences in SGC firing were abolished in GABA(A) receptor blockers. Our data show that cell-type-specific post-traumatic decreases in tonic GABA currents boost SGC excitability after brain injury. Hyperexcitable SGCs could augment dentate throughput to CA3 and contribute substantively to the enhanced risk for epilepsy and memory dysfunction after traumatic brain injury.
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Bolkvadze T, Pitkänen A. Development of post-traumatic epilepsy after controlled cortical impact and lateral fluid-percussion-induced brain injury in the mouse. J Neurotrauma 2012; 29:789-812. [PMID: 22023672 DOI: 10.1089/neu.2011.1954] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The present study investigated the development of hyperexcitability and epilepsy in mice with traumatic brain injury (TBI) induced by controlled cortical impact (CCI) or lateral fluid-percussion injury (FPI), which are the two most commonly used experimental models of human TBI in rodents. TBI was induced with CCI to 50 (14 controls) and with lateral FPI to 45 (15 controls) C57BL/6S adult male mice. The animals were followed-up for 9 months, including three 2-week periods of continuous video-electroencephalographic (EEG) monitoring, and a seizure susceptibility test with pentylenetetrazol (PTZ). In the end, the animals were perfusion-fixed for histology. The experiment included two independent cohorts of animals. Late post-traumatic spontaneous electrographic seizures were detected in 9% of mice after CCI and 3% after lateral FPI. Eighty-two percent of mice after CCI and 71% after lateral FPI had spontaneous epileptiform spiking on EEG. In addition, 58% of mice with lateral FPI showed spontaneous epileptiform discharges. A PTZ test demonstrated increased seizure susceptibility in the majority of mice in both models, compared to control mice. There was no further progression in the occurrence of epilepsy or epileptiform spiking when follow-up was extended from 6 to 9 months. The severity of cortical or hippocampal damage did not differentiate mice with or without epileptiform activity in either model. Finally, two independent series of experiments in both injury models provided comparable data demonstrating reproducibility of the modeling. These data show that different types of impact can trigger epileptogenesis in mice. Even though the frequency of spontaneous seizures in C57BL/6S mice is low, a large majority of animals develop hyperexcitability.
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Affiliation(s)
- Tamuna Bolkvadze
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
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Ono T, Galanopoulou AS. Epilepsy and epileptic syndrome. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 724:99-113. [PMID: 22411237 DOI: 10.1007/978-1-4614-0653-2_8] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Epilepsy is one of the most common neurological disorders. In most patients with epilepsy, seizures respond to available medications. However, a significant number of patients, especially in the setting of medically-intractable epilepsies, may experience different degrees of memory or cognitive impairment, behavioral abnormalities or psychiatric symptoms, which may limit their daily functioning. As a result, in many patients, epilepsy may resemble a neurodegenerative disease. Epileptic seizures and their potential impact on brain development, the progressive nature of epileptogenesis that may functionally alter brain regions involved in cognitive processing, neurodegenerative processes that relate to the underlying etiology, comorbid conditions or epigenetic factors, such as stress, medications, social factors, may all contribute to the progressive nature of epilepsy. Clinical and experimental studies have addressed the pathogenetic mechanisms underlying epileptogenesis and neurodegeneration.We will primarily focus on the findings derived from studies on one of the most common causes of focal onset epilepsy, the temporal lobe epilepsy, which indicate that both processes are progressive and utilize common or interacting pathways. In this chapter we will discuss some of these studies, the potential candidate targets for neuroprotective therapies as well as the attempts to identify early biomarkers of progression and epileptogenesis, so as to implement therapies with early-onset disease-modifying effects.
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Affiliation(s)
- Tomonori Ono
- Saul R. Korey Department of Neurology, Albert Einstein College of Medicine, Bronx, New York, USA
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19
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The involvement of Na+, K+-ATPase activity and free radical generation in the susceptibility to pentylenetetrazol-induced seizures after experimental traumatic brain injury. J Neurol Sci 2011; 308:35-40. [DOI: 10.1016/j.jns.2011.06.030] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Revised: 06/10/2011] [Accepted: 06/16/2011] [Indexed: 01/25/2023]
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20
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Dinocourt C, Aungst S, Yang K, Thompson SM. Homeostatic increase in excitability in area CA1 after Schaffer collateral transection in vivo. Epilepsia 2011; 52:1656-65. [PMID: 21635239 DOI: 10.1111/j.1528-1167.2011.03113.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE Epilepsy is a significant long-term consequence of traumatic brain injury (TBI) and is likely to result from multiple mechanisms. One feature that is common to many forms of TBI is denervation. We asked whether chronic partial denervation in vivo would lead to a homeostatic increase in the excitability of a denervated cell population. METHODS To answer this question, we took advantage of the unique anatomy of the hippocampus where the input to the CA1 neurons, the Schaffer collaterals, could be transected in vivo with preservation of their outputs and only minor cell death. KEY FINDINGS We observed a delayed increase in neuronal excitability, as apparent in extracellular recordings from hippocampal brain slices prepared 14 days (but not 3 days) post lesion. Although population spikes in slices from control and lesioned animals were comparable under resting conditions, application of solutions that were mildly proconvulsive (high K(+) , low Mg(2+) , low concentrations of bicuculline) produced increases in the number of population spikes in slices from lesioned rats, but not in slices from unlesioned sham controls. Denervation did not produce changes in several markers of γ-aminobutyric acid (GABA)ergic synaptic inhibition, including the number of GABAergic neurons, α1 GABA(A) receptor subunits, the vesicular GABA transporter, or miniature inhibitory postsynaptic currents. SIGNIFICANCE We conclude that chronic partial denervation does lead to a delayed homeostatic increase in neuronal excitability, and may, therefore, contribute to the long-term neurologic consequences of TBI.
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Affiliation(s)
- Céline Dinocourt
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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21
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Lin YW, Hsieh CL. Oral Uncaria rhynchophylla (UR) reduces kainic acid-induced epileptic seizures and neuronal death accompanied by attenuating glial cell proliferation and S100B proteins in rats. JOURNAL OF ETHNOPHARMACOLOGY 2011; 135:313-320. [PMID: 21402140 DOI: 10.1016/j.jep.2011.03.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 12/15/2010] [Accepted: 03/05/2011] [Indexed: 05/30/2023]
Abstract
AIM OF THE STUDY Epilepsy is a common clinical syndrome with recurrent neuronal discharges in cerebral cortex and hippocampus. Here we aim to determine the protective role of Uncaria rhynchophylla (UR), an herbal drug belong to Traditional Chinese Medicine (TCM), on epileptic rats. MATERIALS AND METHODS To address this issue, we tested the effect of UR on kainic acid (KA)-induced epileptic seizures and further investigate the underlying mechanisms. RESULTS Oral UR successfully decreased neuronal death and discharges in hippocampal CA1 pyramidal neurons. The population spikes (PSs) were decreased from 4.1 ± 0.4 mV to 2.1 ± 0.3 mV in KA-induced epileptic seizures and UR-treated groups, respectively. Oral UR protected animals from neuronal death induced by KA treatment (from 34 ± 4.6 to 191.7 ± 48.6 neurons/field) through attenuating glial cell proliferation and S100B protein expression but not GABAA and TRPV1 receptors. CONCLUSIONS The above results provide detail mechanisms underlying the neuroprotective action of UR on KA-induced epileptic seizure in hippocampal CA1 neurons.
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Affiliation(s)
- Yi-Wen Lin
- Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan
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22
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Kharlamov EA, Lepsveridze E, Meparishvili M, Solomonia RO, Lu B, Miller ER, Kelly KM, Mtchedlishvili Z. Alterations of GABA(A) and glutamate receptor subunits and heat shock protein in rat hippocampus following traumatic brain injury and in posttraumatic epilepsy. Epilepsy Res 2011; 95:20-34. [PMID: 21439793 DOI: 10.1016/j.eplepsyres.2011.02.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 12/20/2010] [Accepted: 02/18/2011] [Indexed: 12/26/2022]
Abstract
Traumatic brain injury (TBI) can result in the development of posttraumatic epilepsy (PTE). Recently, we reported differential alterations in tonic and phasic GABA(A) receptor (GABA(A)R) currents in hippocampal dentate granule cells 90 days after controlled cortical impact (CCI) (Mtchedlishvili et al., 2010). In the present study, we investigated long-term changes in the protein expression of GABA(A)R α1, α4, γ2, and δ subunits, NMDA (NR2B) and AMPA (GluR1) receptor subunits, and heat shock proteins (HSP70 and HSP90) in the hippocampus of Sprague-Dawley rats evaluated by Western blotting in controls, CCI-injured animals without PTE (CCI group), and CCI-injured animals with PTE (PTE group). No differences were found among all three groups for α1 and α4 subunits. Significant reduction of γ2 protein was observed in the PTE group compared to control. CCI caused a 194% and 127% increase of δ protein in the CCI group compared to control (p<0.0001), and PTE (p<0.0001) groups, respectively. NR2B protein was increased in CCI and PTE groups compared to control (p=0.0001, and p=0.011, respectively). GluR1 protein was significantly decreased in CCI and PTE groups compared to control (p=0.003, and p=0.001, respectively), and in the PTE group compared to the CCI group (p=0.036). HSP70 was increased in CCI and PTE groups compared to control (p=0.014, and p=0.005, respectively); no changes were found in HSP90 expression. These results provide for the first time evidence of long-term alterations of GABA(A) and glutamate receptor subunits and a HSP following CCI.
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Affiliation(s)
- Elena A Kharlamov
- Center for Neuroscience Research, Allegheny-Singer Research Institute, Allegheny General Hospital, 320 East North Avenue, Pittsburgh, PA 15212-4772, United States.
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23
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Zhang B, Chen X, Lin Y, Tan T, Yang Z, Dayao C, Liu L, Jiang R, Zhang J. Impairment of synaptic plasticity in hippocampus is exacerbated by methylprednisolone in a rat model of traumatic brain injury. Brain Res 2011; 1382:165-72. [PMID: 21276433 DOI: 10.1016/j.brainres.2011.01.065] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 01/06/2011] [Accepted: 01/19/2011] [Indexed: 10/18/2022]
Abstract
Patients with traumatic brain injury (TBI) exhibit impaired cognitive capability that is exacerbated with methylprednisolone (MP). Since long-term potentiation (LTP) is a leading cellular model underlying learning, we hypothesize that MP disturbs the electrophysiological character in the hippocampus by decreasing the number of interneurons post-traumatically in the dentate gyrus (DG) and cornu ammonis3 (CA3) regions, resulting in learning deficits. To test this hypothesis, we investigated the alterations of learning abilities and correlated the alternation with hippocampal synaptic plasticity in rats receiving lateral fluid percussion injury (FPI) and being treated with MP. We found that MP aggravates the spatial learning deficiency and changes in the excitability of the DG and cornu ammonis1 (CA1) areas in rats subjected to FPI. The functional and electrophysiological deficits are associated with a decrease in the number of parvalbumin-immunoreactive (PV-IR) and cholecystokinin-immunoreactive (CCK-IR) GABAergic cells. The data suggest that MP therapy may decrease the number of DG interneurons in post-traumatic hippocampus, resulting in the aggravated deficits of learning ability induced by TBI.
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Affiliation(s)
- Baoliang Zhang
- Department of Neurosurgery, Tianjin Neurological Institute, Tianjin Medical University General Hospital, 154 Anshan Road, Tianjin 300052, PR China
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Yamashita S, Hasuo H, Tokutomi T, Shigemori M, Akasu T. Edaravone attenuates impairment of synaptic plasticity in granule cell layer of the dentate gyrus following traumatic brain injury. Kurume Med J 2011; 58:47-58. [PMID: 22251821 DOI: 10.2739/kurumemedj.58.47] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Effects of edaravone, a free radical scavenger, on post-traumatic impairment of long-term potentiation (LTP) were examined in granule cell layers of the dentate gyrus (DG) in vitro. Field EPSPs (fEPSPs) evoked by stimulation of the perforant path (PP) were recorded extracellularly in the DG one week after a moderate impact applied by a fluid percussion injury (FPI) device. High frequency stimulation (HFS) of the PP caused LTP of the fEPSP-slope in slices from naïve and sham-operated rats, however, the LTP was strongly depressed in slices from FPI rats. Intraperitoneal administration of edaravone 15 min after FPI prevented the hyperactivities of DG neurons and attenuated impairment of the LTP in FPI rat dentate granular cells. In vitro application of spermine NONOate (sp-NO), a nitric oxide (NO) donor, for 30 min produced a gradual increase in the fEPSP-slope, lasting for more than 2 h. Edaravone attenuated the enhancement of the fEPSP-slope induced by sp-NO. After sp-NO treatment HFS could not produce an obvious LTP in the DG granule cell layer. Pretreatment of DG slices with edaravone prevented the sp-NO-induced impairment of LTP. These results suggest that administration of edaravone after FPI protects against post-traumatic impairment of LTP in granule cell layers of the DG, possibly by scavenging NO-related radicals.
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Affiliation(s)
- Shin Yamashita
- Department of Physiology, Kurume University School of Medicine, Kurume University, Kurume 830-0011, Japan
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25
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Carter DS, Deshpande LS, Rafiq A, Sombati S, DeLorenzo RJ. Characterization of spontaneous recurrent epileptiform discharges in hippocampal-entorhinal cortical slices prepared from chronic epileptic animals. Seizure 2010; 20:218-24. [PMID: 21168348 DOI: 10.1016/j.seizure.2010.11.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 11/18/2010] [Accepted: 11/22/2010] [Indexed: 11/25/2022] Open
Abstract
Epilepsy, a common neurological disorder, is characterized by the occurrence of spontaneous recurrent epileptiform discharges (SREDs). Acquired epilepsy is associated with long-term neuronal plasticity changes in the hippocampus resulting in the expression of spontaneous recurrent seizures. The purpose of this study is to evaluate and characterize endogenous epileptiform activity in hippocampal-entorhinal cortical (HEC) slices from epileptic animals. This study employed HEC slices isolated from a large series of control and epileptic animals to evaluate and compare the presence, degree and localization of endogenous SREDs using extracellular and whole cell current clamp recordings. Animals were made epileptic using the pilocarpine model of epilepsy. Extracellular field potentials were recorded simultaneously from areas CA1, CA3, dentate gyrus, and entorhinal cortex and whole cell current clamp recordings were obtained from CA3 neurons. All regions from epileptic HEC slices (n=53) expressed SREDs, with an average frequency of 1.3Hz. In contrast, control slices (n=24) did not manifest any SREDs. Epileptic HEC slices demonstrated slow and fast firing patterns of SREDs. Whole cell current clamp recordings from epileptic HEC slices showed that CA3 neurons exhibited paroxysmal depolarizing shifts associated with these SREDs. To our knowledge this is the first significant demonstration of endogenous SREDs in a large series of HEC slices from epileptic animals in comparison to controls. Epileptiform discharges were found to propagate around hippocampal circuits. HEC slices from epileptic animals that manifest SREDs provide a novel model to study in vitro seizure activity in tissue prepared from epileptic animals.
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Affiliation(s)
- Dawn S Carter
- Department of Neurology, Virginia Commonwealth University, Richmond, VA, United States
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26
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Atkins CM, Truettner JS, Lotocki G, Sanchez-Molano J, Kang Y, Alonso OF, Sick TJ, Dietrich WD, Bramlett HM. Post-traumatic seizure susceptibility is attenuated by hypothermia therapy. Eur J Neurosci 2010; 32:1912-20. [PMID: 21044182 DOI: 10.1111/j.1460-9568.2010.07467.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Traumatic brain injury (TBI) is a major risk factor for the subsequent development of epilepsy. Currently, chronic seizures after brain injury are often poorly controlled by available antiepileptic drugs. Hypothermia treatment, a modest reduction in brain temperature, reduces inflammation, activates pro-survival signaling pathways, and improves cognitive outcome after TBI. Given the well-known effect of therapeutic hypothermia to ameliorate pathological changes in the brain after TBI, we hypothesized that hypothermia therapy may attenuate the development of post-traumatic epilepsy and some of the pathomechanisms that underlie seizure formation. To test this hypothesis, adult male Sprague Dawley rats received moderate parasagittal fluid-percussion brain injury, and were then maintained at normothermic or moderate hypothermic temperatures for 4 h. At 12 weeks after recovery, seizure susceptibility was assessed by challenging the animals with pentylenetetrazole, a GABA(A) receptor antagonist. Pentylenetetrazole elicited a significant increase in seizure frequency in TBI normothermic animals as compared with sham surgery animals and this was significantly reduced in TBI hypothermic animals. Early hypothermia treatment did not rescue chronic dentate hilar neuronal loss nor did it improve loss of doublecortin-labeled cells in the dentate gyrus post-seizures. However, mossy fiber sprouting was significantly attenuated by hypothermia therapy. These findings demonstrate that reductions in seizure susceptibility after TBI are improved with post-traumatic hypothermia and provide a new therapeutic avenue for the treatment of post-traumatic epilepsy.
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Affiliation(s)
- Coleen M Atkins
- Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, FL 33136, USA
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27
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Bao YH, Bramlett HM, Atkins CM, Truettner JS, Lotocki G, Alonso OF, Dietrich WD. Post-traumatic seizures exacerbate histopathological damage after fluid-percussion brain injury. J Neurotrauma 2010; 28:35-42. [PMID: 20836615 DOI: 10.1089/neu.2010.1383] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The purpose of this study was to investigate the effects of an induced period of post-traumatic epilepsy (PTE) on the histopathological damage caused by traumatic brain injury (TBI). Male Sprague Dawley rats were given a moderate parasagittal fluid-percussion brain injury (1.9-2.1 atm) or sham surgery. At 2 weeks after surgery, seizures were induced by administration of a GABA(A) receptor antagonist, pentylenetetrazole (PTZ, 30 mg/kg). Seizures were then assessed over a 1-h period using the Racine clinical rating scale. To evaluate whether TBI-induced pathology was exacerbated by the seizures, contusion volume and cortical and hippocampal CA3 neuronal cell loss were measured 3 days after seizures. Nearly all TBI rats showed clinical signs of PTE following the decrease in inhibitory activity. In contrast, clinically evident seizures were not observed in TBI rats given saline or sham-operated rats given PTZ. Contusions in TBI-PTZ-treated rats were significantly increased compared to the TBI-saline-treated group (p < 0.001). In addition, the TBI-PTZ rats showed less NeuN-immunoreactive cells within the ipsilateral parietal cerebral cortex (p < 0.05) and there was a trend for decreased hippocampal CA3 neurons in TBI-PTZ rats compared with TBI-saline or sham-operated rats. These results demonstrate that an induced period of post-traumatic seizures significantly exacerbates the structural damage caused by TBI. These findings emphasize the need to control seizures after TBI to limit even further damage to the injured brain.
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Affiliation(s)
- Ying-hui Bao
- Department of Neurological Surgery, Neurotrauma Research Center, and The Miami Project to Cure Paralysis, University of Miami School of Medicine, Miami, Florida, USA
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Schwartzkroin PA, Wenzel HJ, Lyeth BG, Poon CC, Delance A, Van KC, Campos L, Nguyen DV. Does ketogenic diet alter seizure sensitivity and cell loss following fluid percussion injury? Epilepsy Res 2010; 92:74-84. [PMID: 20863664 DOI: 10.1016/j.eplepsyres.2010.08.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Revised: 08/16/2010] [Accepted: 08/18/2010] [Indexed: 10/19/2022]
Abstract
Traumatic brain injury (TBI) frequently leads to epilepsy. The process of epileptogenesis - the development of that seizure state - is still poorly understood, and effective antiepileptogenic treatments have yet to be identified. The ketogenic diet (KD) has been shown to be effective as an antiepileptic therapy, but has not been extensively tested for its efficacy in preventing the development of the seizure state, and certainly not within the context of TBI-induced epileptogenesis. We have used a rat model of TBI - fluid percussion injury (FPI) - to test the hypothesis that KD treatment is antiepileptogenic and protects the brain from neuronal cell loss following TBI. Rats fed a KD had a higher seizure threshold (longer latency to flurothyl-induced seizure activity) than rats fed a standard diet (SD); this effect was seen when KD was in place at the time of seizure testing (3 and 6 weeks following FPI), but was absent when KD had been replaced by SD at time of testing. FPI caused significant hippocampal cell loss in both KD-fed and SD-fed rats; the degree of cell loss appeared to be reduced by KD treatment before FPI but not after FPI. These results are consistent with prior demonstrations that KD raises seizure threshold, but do not provide support for the hypothesis that KD administered for a limited time directly before or after FPI alters later seizure sensitivity; that is, within the limits of this model and protocol, there is no evidence for KD-induced antiepileptogenesis.
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Affiliation(s)
- Philip A Schwartzkroin
- Department of Neurological Surgery, University of California, Davis, Davis, CA 95616, United States.
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Abstract
A Model of Posttraumatic Epilepsy Induced by Lateral Fluid-Percussion Brain Injury in Rats Kharatishvili I, Nissinen JP, McIntosh TK, Pitkänen A Neuroscience 2006;140:685–697 Although traumatic brain injury is a major cause of symptomatic epilepsy, the mechanism by which it leads to recurrent seizures is unknown. An animal model of posttraumatic epilepsy that reliably reproduces the clinical sequelae of human traumatic brain injury is essential to identify the molecular and cellular substrates of posttraumatic epileptogenesis, and perform preclinical screening of new antiepileptogenic compounds. We studied the electrophysiologic, behavioral, and structural features of posttraumatic epilepsy induced by severe, non-penetrating lateral fluid-percussion brain injury in rats. Data from two independent experiments indicated that 43% to 50% of injured animals developed epilepsy, with a latency period between 7 weeks to 1 year. Mean seizure frequency was 0.3 ± 0.2 seizures per day and mean seizure duration was 113 ± 46 s. Behavioral seizure severity increased over time in the majority of animals. Secondarily generalized seizures comprised an average of 66 ± 37% of all seizures. Mossy fiber sprouting was increased in the ipsilateral hippocampus of animals with posttraumatic epilepsy compared with those subjected to traumatic brain injury without epilepsy. Stereologic cell counts indicated a loss of dentate hilar neurons ipsilaterally following traumatic brain injury. Our data suggest that posttraumatic epilepsy occurs with a frequency of 40% to 50% after severe non-penetrating fluid-percussion brain injury in rats, and that the lateral fluid percussion model can serve as a clinically relevant tool for pathophysiologic and preclinical studies.
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Garga N, Lowenstein DH. Posttraumatic epilepsy: a major problem in desperate need of major advances. Epilepsy Curr 2010; 6:1-5. [PMID: 16477313 PMCID: PMC1363374 DOI: 10.1111/j.1535-7511.2005.00083.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
This brief review is meant to provide an update on the data from clinical and laboratory studies that have provided insight into the mechanisms underlying the development of epilepsy following traumatic brain injury (TBI). The link between severe brain trauma and epilepsy in humans is well recognized. However, we have yet to identify an effective intervention to prevent the development of epilepsy in patients who are at risk after TBI. Laboratory studies, which have relied primarily on the fluid-percussion model, have documented long-term hyperexcitability associated with TBI, and recent studies are shedding light on the structural and electrophysiological abnormalities that may underlie epileptogenesis in this setting. Nonetheless, given the extent of the clinical problem and our current state of knowledge, this area of epilepsy research deserves far more attention.
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Affiliation(s)
- Nina Garga
- Department of Neurology, University of California, San Francisco, USA
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31
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Gibson CJ, Meyer RC, Hamm RJ. Traumatic brain injury and the effects of diazepam, diltiazem, and MK-801 on GABA-A receptor subunit expression in rat hippocampus. J Biomed Sci 2010; 17:38. [PMID: 20482789 PMCID: PMC2893123 DOI: 10.1186/1423-0127-17-38] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Accepted: 05/18/2010] [Indexed: 02/07/2023] Open
Abstract
Background Excitatory amino acid release and subsequent biochemical cascades following traumatic brain injury (TBI) have been well documented, especially glutamate-related excitotoxicity. The effects of TBI on the essential functions of inhibitory GABA-A receptors, however, are poorly understood. Methods We used Western blot procedures to test whether in vivo TBI in rat altered the protein expression of hippocampal GABA-A receptor subunits α1, α2, α3, α5, β3, and γ2 at 3 h, 6 h, 24 h, and 7 days post-injuy. We then used pre-injury injections of MK-801 to block calcium influx through the NMDA receptor, diltiazem to block L-type voltage-gated calcium influx, or diazepam to enhance chloride conductance, and re-examined the protein expressions of α1, α2, α3, and γ2, all of which were altered by TBI in the first study and all of which are important constituents in benzodiazepine-sensitive GABA-A receptors. Results Western blot analysis revealed no injury-induced alterations in protein expression for GABA-A receptor α2 or α5 subunits at any time point post-injury. Significant time-dependent changes in α1, α3, β3, and γ2 protein expression. The pattern of alterations to GABA-A subunits was nearly identical after diltiazem and diazepam treatment, and MK-801 normalized expression of all subunits 24 hours post-TBI. Conclusions These studies are the first to demonstrate that GABA-A receptor subunit expression is altered by TBI in vivo, and these alterations may be driven by calcium-mediated cascades in hippocampal neurons. Changes in GABA-A receptors in the hippocampus after TBI may have far-reaching consequences considering their essential importance in maintaining inhibitory balance and their extensive impact on neuronal function.
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Affiliation(s)
- Cynthia J Gibson
- Department of Psychology, Washington College, Chestertown, MD 21620, USA.
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Bouilleret V, Cardamone L, Liu YR, Fang K, Myers DE, O'Brien TJ. Progressive brain changes on serial manganese-enhanced MRI following traumatic brain injury in the rat. J Neurotrauma 2010; 26:1999-2013. [PMID: 19604101 DOI: 10.1089/neu.2009.0943] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Traumatic brain injury (TBI) has a high incidence of long-term morbidity. Manganese-enhanced MRI (MEMRI) provides high contrast structural and functional detail of the brain in-vivo. The study utilized serial MEMRI scanning in the fluid percussion injury (FPI) rat's model to assess long-term changes in the brain following TBI. Rats underwent a left-sided craniotomy and a 3.5 atmosphere FPI pulse (n = 23) or sham procedure (n = 22). MEMRI acquisition was performed at baseline, 1 day, 1 month, and 6 months after FPI. Volume changes and MnCl(2) enhancement were measured blindly using region-of-interest analysis and the results analyzed with repeated measures MANOVA. Compared to the shams, FPI animals showed a progressive decrease in brain volume from 1 (right, p = 0.02; left, p = 0.008) to 6 months (right, p = 0.04; left, p = 0.006), with progression over time (F = 7.16, p = 0.00018). Similar changes were found in the cortex and the hippocampus. Conversely, the ventricular volume was increased at 1 (p = 0.02) and 6 months (p = 0.003), with progression over time (F = 7.27, p = 0.0001). There were no differences in thalamic or amygdalae volumes. The severity of the early neuromotor deficits and the T2 signal intensity of the subacute focal lesion were highly predictive of the severity of the long-term hippocampal decrease, and the former was also associated with the degree of neuronal sprouting. Differential MnCl(2) enhancement occurred only in the dentate gyrus at 1 month on the side of trauma (p = 0.04). Progressive functional and structural changes occur in specific brain regions post-FPI. The severity of the neuromotor deficit and focal signal changes on MRI subacutely post-injury are predictive of severity of these long-term neurodegenerative changes.
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Affiliation(s)
- Viviane Bouilleret
- Department of Medicine (RMH), University of Melbourne, Victoria, Australia
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Echegoyen J, Armstrong C, Morgan RJ, Soltesz I. Single application of a CB1 receptor antagonist rapidly following head injury prevents long-term hyperexcitability in a rat model. Epilepsy Res 2009; 85:123-7. [PMID: 19369036 DOI: 10.1016/j.eplepsyres.2009.02.019] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Revised: 02/10/2009] [Accepted: 02/22/2009] [Indexed: 11/18/2022]
Abstract
Effective prophylaxis for post-traumatic epilepsy currently does not exist, and clinical trials using anticonvulsant drugs have yielded no long-term antiepileptogenic effects. We report that a single, rapid post-traumatic application of the proconvulsant cannabinoid type-1 (CB1) receptor antagonist SR141716A (Rimonabant-Acomplia) abolishes the long-term increase in seizure susceptibility caused by head injury in rats. These results indicate that, paradoxically, a seizure-enhancing drug may disrupt the epileptogenic process if applied within a short therapeutic time window.
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Affiliation(s)
- Julio Echegoyen
- Department of Anatomy and Neurobiology, University of California, Irvine, CA 92697-1280, United States
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Badawy RAB, Harvey AS, Macdonell RAL. Cortical hyperexcitability and epileptogenesis: Understanding the mechanisms of epilepsy - part 2. J Clin Neurosci 2009; 16:485-500. [PMID: 19230676 DOI: 10.1016/j.jocn.2008.10.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Accepted: 10/03/2008] [Indexed: 12/19/2022]
Abstract
Epilepsy encompasses a diverse group of seizure disorders caused by a variety of structural, cellular and molecular alterations of the brain primarily affecting the cerebral cortex, leading to recurrent unprovoked epileptic seizures. In this two-part review we examine the mechanisms underlying normal neuronal function and those predisposing to recurrent epileptic seizures starting at the most basic cellular derangements (Part 1, Volume 16, Issue 3) and working up to the highly complex epileptic networks and factors that modulate the predisposition to seizures (Part 2). We attempt to show that multiple factors can modify the epileptic process and that different mechanisms underlie different types of epilepsy, and in most situations there is an interplay between multiple genetic and environmental factors.
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Affiliation(s)
- Radwa A B Badawy
- Department of Neurology, Austin Health, Heidelberg, Victoria, Australia
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Pitkänen A, Immonen RJ, Gröhn OH, Kharatishvili I. From traumatic brain injury to posttraumatic epilepsy: What animal models tell us about the process and treatment options. Epilepsia 2009; 50 Suppl 2:21-9. [DOI: 10.1111/j.1528-1167.2008.02007.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Diaz-Arrastia R, Agostini MA, Madden CJ, Van Ness PC. Posttraumatic epilepsy: The endophenotypes of a human model of epileptogenesis. Epilepsia 2009; 50 Suppl 2:14-20. [DOI: 10.1111/j.1528-1167.2008.02006.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ooba S, Hasuo H, Shigemori M, Yamashita S, Akasu T. Mild hypothermia prevents post-traumatic hyperactivity of excitatory synapses in rat hippocampal CA1 pyramidal neurons. Kurume Med J 2009; 56:49-59. [PMID: 20505282 DOI: 10.2739/kurumemedj.56.49] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The present experiment examined the effect of mild hypothermia (35 degrees C) on the post-traumatic hyperactivity of rat hippocampal CA1 neurons in horizontal brain slices. One week after fluid percussion injury (FPI), the optical response evoked by stimulation of the Schaffer collaterals increased in amplitude and propagation area in hippocampal CA1 slices. FPI did not alter the fast optical response that reflected the action potential of the Schaffer collaterals but enhanced the slow component that reflected the excitatory postsynaptic response. FPI increased the slope of the input-output relation (I/O function), suggesting that FPI increases the efficacy of excitatory synaptic transmission in the hippocampal CA1 pyramidal neurons. To examine the effect of low temperature on post-traumatic hyperactivity of hippocampal CA1 neurons, mild hypothermia (35 degrees C) was administered to rats 15 min after FPI and maintained for 1-3 h. One week after FPI, the activity of hippocampal CA1 neurons in rats with mild hypothermia appeared to be reduced as compared with those receiving FPI alone. The post-traumatic enhancement of the I/O function of the slow optical response was prevented by mild hypothermia. These results suggest that mild hypothermia applied 15 min after FPI attenuates the post-traumatic hyperactivity of excitatory synapses in rat hippocampal CA1 neurons.
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Affiliation(s)
- Satomi Ooba
- Department of Physiology, Kurume University School of Medicine, Kurume, Japan
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A novel apparatus for lateral fluid percussion injury in the rat. J Neurosci Methods 2008; 177:267-72. [PMID: 19022291 DOI: 10.1016/j.jneumeth.2008.10.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Revised: 10/09/2008] [Accepted: 10/10/2008] [Indexed: 11/22/2022]
Abstract
Lateral fluid percussion injury (LFPI) is the most commonly used experimental model of human traumatic brain injury (TBI). To date, investigators using this model have produced injury using a pendulum-and-piston-based device (PPBD) to drive fluid against an intact dural surface. Two disadvantages of this method, however, are (1) the necessary reliance on operator skill to position and release the pendulum, and (2) reductions in reproducibility due to variable friction between the piston's o-rings and the cylinder. To counteract these disadvantages, we designed a low-priced, novel, fluid percussion apparatus that delivers a pressure pulse of air to a standing column of fluid, forcing it against the intact dural surface. The pressure waveforms generated by this apparatus are similar to those reported in the LFPI/PPBD literature and had little variation in appearance between trials. In addition, our apparatus produced an acute and chronic TBI syndrome similar to that in the LFPI/PPBD literature, as quantified by histological changes, MRI structural changes and chronic behavioral sequelae.
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Sun DA, Deshpande LS, Sombati S, Baranova A, Wilson MS, Hamm RJ, DeLorenzo RJ. Traumatic brain injury causes a long-lasting calcium (Ca2+)-plateau of elevated intracellular Ca levels and altered Ca2+ homeostatic mechanisms in hippocampal neurons surviving brain injury. Eur J Neurosci 2008; 27:1659-72. [PMID: 18371074 DOI: 10.1111/j.1460-9568.2008.06156.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Traumatic brain injury (TBI) survivors often suffer chronically from significant morbidity associated with cognitive deficits, behavioral difficulties and a post-traumatic syndrome and thus it is important to understand the pathophysiology of these long-term plasticity changes after TBI. Calcium (Ca2+) has been implicated in the pathophysiology of TBI-induced neuronal death and other forms of brain injury including stroke and status epilepticus. However, the potential role of long-term changes in neuronal Ca2+ dynamics after TBI has not been evaluated. In the present study, we measured basal free intracellular Ca2+ concentration ([Ca2+](i)) in acutely isolated CA3 hippocampal neurons from Sprague-Dawley rats at 1, 7 and 30 days after moderate central fluid percussion injury. Basal [Ca2+](i) was significantly elevated when measured 1 and 7 days post-TBI without evidence of neuronal death. Basal [Ca2+](i) returned to normal when measured 30 days post-TBI. In contrast, abnormalities in Ca2+ homeostasis were found for as long as 30 days after TBI. Studies evaluating the mechanisms underlying the altered Ca2+ homeostasis in TBI neurons indicated that necrotic or apoptotic cell death and abnormalities in Ca2+ influx and efflux mechanisms could not account for these changes and suggested that long-term changes in Ca2+ buffering or Ca2+ sequestration/release mechanisms underlie these changes in Ca2+ homeostasis after TBI. Further elucidation of the mechanisms of altered Ca2+ homeostasis in traumatized, surviving neurons in TBI may offer novel therapeutic interventions that may contribute to the treatment and relief of some of the morbidity associated with TBI.
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Affiliation(s)
- David A Sun
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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Cohen AS, Pfister BJ, Schwarzbach E, Grady MS, Goforth PB, Satin LS. Injury-induced alterations in CNS electrophysiology. PROGRESS IN BRAIN RESEARCH 2007; 161:143-69. [PMID: 17618975 DOI: 10.1016/s0079-6123(06)61010-8] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Mild to moderate cases of traumatic brain injury (TBI) are very common, but are not always associated with the overt pathophysiogical changes seen following severe trauma. While neuronal death has been considered to be a major factor, the pervasive memory, cognitive and motor function deficits suffered by many mild TBI patients do not always correlate with cell loss. Therefore, we assert that functional impairment may result from alterations in surviving neurons. Current research has begun to explore CNS synaptic circuits after traumatic injury. Here we review significant findings made using in vivo and in vitro models of TBI that provide mechanistic insight into injury-induced alterations in synaptic electrophysiology. In the hippocampus, research now suggests that TBI regionally alters the delicate balance between excitatory and inhibitory neurotransmission in surviving neurons, disrupting the normal functioning of synaptic circuits. In another approach, a simplified model of neuronal stretch injury in vitro, has been used to directly explore how injury impacts the physiology and cell biology of neurons in the absence of alterations in blood flow, blood brain barrier integrity, or oxygenation associated with in vivo models of brain injury. This chapter discusses how these two models alter excitatory and inhibitory synaptic transmission at the receptor, cellular and circuit levels and how these alterations contribute to cognitive impairment and a reduction in seizure threshold associated with human concussive brain injury.
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Affiliation(s)
- Akiva S Cohen
- Department of Pediatrics, University of Pennsylvania, School of Medicine and Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA.
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DeLorenzo RJ, Sun DA, Deshpande LS. Erratum to "Cellular mechanisms underlying acquired epilepsy: the calcium hypothesis of the induction and maintenance of epilepsy." [Pharmacol. Ther. 105(3) (2005) 229-266]. Pharmacol Ther 2006; 111:288-325. [PMID: 16832874 DOI: 10.1016/j.pharmthera.2004.10.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Epilepsy is one of the most common neurological disorders. Although epilepsy can be idiopathic, it is estimated that up to 50% of all epilepsy cases are initiated by neurological insults and are called acquired epilepsy (AE). AE develops in 3 phases: (1) the injury [central nervous system (CNS) insult]. (2) epileptogenesis (latency), and (3) the chronic epileptic (spontaneous recurrent seizure) phases. Status epilepticus (SE), stroke, and traumatic brain injury (TBI) are 3 major examples of common brain injuries that can lead to the development of AE. It is especially important to understand the molecular mechanisms that cause AE because it may lead to innovative strategies to prevent or cure this common condition. Recent studies have offered new insights into the cause of AE and indicate that injury-induced alterations in intracellular calcium concentration levels ([Ca(2+)](i)) and calcium homeostatic mechanisms play a role in the development and maintenance of AE. The injuries that cause AE are different, but the share a common molecular mechanism for producing brain damage--an increase in extracellular glutamate and are exposed to increased [Ca(2+)](i) are the cellular substrates to develop epilepsy because dead cells do not seize. The neurons that survive injury sustain permanent long-term plasticity changes in [Ca(2+)](i) and calcium homeostatic mechanisms that are permanent and are a prominent feature of the epileptic phenotype. In the last several years, evidence has accumulated indicating that the prolonged alteration in neuronal calcium dynamics plays an important role in the induction and maintenance of the prolonged neuroplasticity changes underlying the epileptic phenotype. Understanding the role of calcium as a second messenger in the induction and maintenance of epilepsy may provide novel insights into therapeutic advances that will prevent and even cure AE.
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Affiliation(s)
- Robert J DeLorenzo
- Department of Neurology, Virginia Commonwealth University, School of Medicine, Richmond, 23298-0599, USA.
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Swartz BE, Houser CR, Tomiyasu U, Walsh GO, DeSalles A, Rich JR, Delgado-Escueta A. Hippocampal Cell Loss in Posttraumatic Human Epilepsy. Epilepsia 2006; 47:1373-82. [PMID: 16922884 DOI: 10.1111/j.1528-1167.2006.00602.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE We performed this study to determine whether significant head trauma in human adults can result in hippocampal cell loss, particularly in hilar (polymorph) and CA3 neurons, similar to that observed in animal models of traumatic brain injury. We examined the incidence of hippocampal pathology and its relation to temporal neocortical pathology, neuronal reorganization, and other variables. METHODS Twenty-one of 200 sequential temporal lobectomies had only trauma as a risk factor for epilepsy. Tissue specimens from temporal neocortex and hippocampus were stained with glial fibrillary acidic protein (GFAP) and hematoxylin and eosin (H&E). Eleven hippocampal specimens had additional analysis of neuronal distributions by using cresyl violet and immunolabeling of a neuron-specific nuclear protein. RESULTS The median age at onset of trauma was 19 years, the median time between trauma and onset of seizures was 2 years, and the median epilepsy duration was 16 years. The length of the latent period was inversely related to the age at the time of trauma (r=0.75; Spearman). The neocortex showed gliosis in all specimens, with hemosiderosis (n=8) or heterotopias (n=6) in some, a distribution differing from chance (p=0.02; Fisher). Hippocampal neuronal loss was found in 94% of specimens, and all of these had cell loss in the polymorph (hilar) region of the dentate gyrus. Hilar cell loss ranged from mild, when cell loss was confined to the hilus, to severe, when cell loss extended into CA3 and CA1. Some degree of mossy fiber sprouting was found in the dentate gyrus of all 10 specimens in which it was evaluated. Granule cell dispersion (n=4) was seen only in specimens with moderate to severe neuronal loss. CONCLUSIONS Neocortical pathology was universally present after trauma. Neuronal loss in the hilar region was the most consistent finding in the hippocampal formation, similar to that found in the fluid-percussion model of traumatic head injury. These findings support the idea that head trauma can induce hippocampal epilepsy in humans in the absence of other known risk factors.
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Affiliation(s)
- Barbara E Swartz
- Hoag Hospital Memorial Presbyterian Epilepsy Center, Newport Beach 92658-6100, and California Comprehensive Epilepsy Program, UCLA, Los Angeles, CA, USA.
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Abstract
Epilepsy is a major unfavorable long-term consequence of traumatic brain injury (TBI). Moreover, TBI is one of the most important predisposing factors for the development of epilepsy, particularly in young adults. Understanding the molecular and cellular cascades that lead to the development of post-traumatic epilepsy (PTE) is key for preventing its development or modifying the disease process in such a way that epilepsy, if it develops, is milder and easier-to-treat. Tissue from TBI patients undergoing epileptogenesis is not available for such studies, which underscores the importance of developing clinically relevant animal models of PTE. The goal of this review is to (1) provide a description of PTE in humans, which is critical for the development of clinically relevant models of PTE, (2) review the characteristics of currently available PTE models, and (3) provide suggestions for the development of future models of PTE based on our current understanding of the mechanisms of TBI and epilepsy. The development of clinically relevant models of PTE is critical to advance our understanding of the mechanisms of post-traumatic epileptogenesis and epilepsy, as well as for producing breakthroughs in the development and testing of novel antiepileptogenic treatments.
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Affiliation(s)
- Asla Pitkänen
- Epilepsy Research Laboratory, AI Virtanen Institute for Molecular Sciences, University of Kuopio, Kuopio, Finland.
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Abstract
Most neurological and psychiatric disorders involve selective or preferential impairments of neurotransmitter systems. Therefore, studies of functional transmitter pathophysiology in human brain are of unique importance in view of the development of effective, mechanism-based, therapeutic modalities. It is well known that central nervous system functional proteins, including receptors, transporters, ion channels, and enzymes, can exhibit high heterogeneity in terms of structure, function, and pharmacological profile. If the existence of types and subtypes of functional proteins amplifies the possibility of developing selective drugs, such heterogeneity certainly increases the likelihood of interspecies differences. It is therefore essential, before choosing animal models to be used in preclinical pharmacology experimentation, to establish whether functionally corresponding proteins in men and animals also display identical pharmacological profiles. Because of evidence that scaffolding proteins, trafficking between plasma membrane and intracellular pools, phosphorylation and allosteric modulators can affect the function of receptors and transporters, experiments with human clones expressed in host cells where the environment of native receptors is rarely reproduced should be interpreted with caution. Thus, the use of neurosurgically removed fresh human brain tissue samples in which receptors, transporters, ion channels, and enzymes essentially retain their natural environment represents a unique experimental approach to enlarge our understanding of human brain processes and to help in the choice of appropriate animal models. Using this experimental approach, many human brain functional proteins, in particular transmitter receptors, have been characterized in terms of localization, function, and pharmacological properties.
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Affiliation(s)
- Maurizio Raiteri
- Dipartimento di Medicina Sperimentale, Sezione di Farmacologia e Tossicologia, Viale Cembrano 4, 16148 Genova, Italy.
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Kharatishvili I, Nissinen JP, McIntosh TK, Pitkänen A. A model of posttraumatic epilepsy induced by lateral fluid-percussion brain injury in rats. Neuroscience 2006; 140:685-97. [PMID: 16650603 DOI: 10.1016/j.neuroscience.2006.03.012] [Citation(s) in RCA: 266] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 03/03/2006] [Accepted: 03/07/2006] [Indexed: 11/30/2022]
Abstract
Although traumatic brain injury is a major cause of symptomatic epilepsy, the mechanism by which it leads to recurrent seizures is unknown. An animal model of posttraumatic epilepsy that reliably reproduces the clinical sequelae of human traumatic brain injury is essential to identify the molecular and cellular substrates of posttraumatic epileptogenesis, and perform preclinical screening of new antiepileptogenic compounds. We studied the electrophysiologic, behavioral, and structural features of posttraumatic epilepsy induced by severe, non-penetrating lateral fluid-percussion brain injury in rats. Data from two independent experiments indicated that 43% to 50% of injured animals developed epilepsy, with a latency period between 7 weeks to 1 year. Mean seizure frequency was 0.3+/-0.2 seizures per day and mean seizure duration was 113+/-46 s. Behavioral seizure severity increased over time in the majority of animals. Secondarily-generalized seizures comprised an average of 66+/-37% of all seizures. Mossy fiber sprouting was increased in the ipsilateral hippocampus of animals with posttraumatic epilepsy compared with those subjected to traumatic brain injury without epilepsy. Stereologic cell counts indicated a loss of dentate hilar neurons ipsilaterally following traumatic brain injury. Our data suggest that posttraumatic epilepsy occurs with a frequency of 40% to 50% after severe non-penetrating fluid-percussion brain injury in rats, and that the lateral fluid percussion model can serve as a clinically-relevant tool for pathophysiologic and preclinical studies.
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Affiliation(s)
- I Kharatishvili
- Epilepsy Research Laboratory, A. I. Virtanen Institute for Molecular Sciences, University of Kuopio, and Department of Neurology, Kuopio University Hospital, Finland
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46
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Kochanek PM, Vagni VA, Janesko KL, Washington CB, Crumrine PK, Garman RH, Jenkins LW, Clark RSB, Homanics GE, Dixon CE, Schnermann J, Jackson EK. Adenosine A1 receptor knockout mice develop lethal status epilepticus after experimental traumatic brain injury. J Cereb Blood Flow Metab 2006; 26:565-75. [PMID: 16121125 DOI: 10.1038/sj.jcbfm.9600218] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Adenosine, acting at A1 receptors, exhibits anticonvulsant effects in experimental epilepsy--and inhibits progression to status epilepticus (SE). Seizures after traumatic brain injury (TBI) may contribute to pathophysiology. Thus, we hypothesized that endogenous adenosine, acting via A1 receptors, mediates antiepileptic benefit after experimental TBI. We subjected A1-receptor knockout (ko) mice, heterozygotes, and wild-type (wt) littermates (n=115) to controlled cortical impact (CCI). We used four outcome protocols in male mice: (1) observation for seizures, SE, and mortality in the initial 2 h, (2) assessment of seizure score (electroencephalogram (EEG)) in the initial 2 h, (3) assessment of mortality at 24 h across injury levels, and (4) serial assessment of arterial blood pressure, heart rate, blood gases, and hematocrit. Lastly, to assess the influence of gender on this observation, we observed female mice for seizures, SE, and mortality in the initial 2 h. Seizure activity was noted in 83% of male ko mice in the initial 2 h, but was seen in no heterozygotes and only 33% of wt (P<0.05). Seizures in wt were brief (1 to 2 secs). In contrast, SE involving lethal sustained (>1 h) tonic clonic activity was uniquely seen in ko mice after CCI (50% incidence in males), (P<0.05). Seizure score was twofold higher in ko mice after CCI versus either heterozygote or wt (P<0.05). An injury-intensity dose-response for 24 h mortality was seen in ko mice (P<0.05). Physiologic parameters were similar between genotypes. Seizures were seen in 100% of female ko mice after CCI versus 14% of heterozygotes and 25% wt (P<0.05) and SE was restricted to the ko mice (83% incidence). Our data suggest a critical endogenous anticonvulsant action of adenosine at A1 receptors early after experimental TBI.
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Affiliation(s)
- Patrick M Kochanek
- Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260, USA.
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Setkowicz Z, Nowak B, Janeczko K. Neocortical injuries at different developmental stages determine different susceptibility to seizures induced in adulthood. Epilepsy Res 2006; 68:255-63. [PMID: 16387474 DOI: 10.1016/j.eplepsyres.2005.11.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2005] [Revised: 10/26/2005] [Accepted: 11/27/2005] [Indexed: 11/29/2022]
Abstract
Gliosis, axonal sprouting and remodelling of nerve connections in the injured brain have been regarded as epileptogenic processes dependent on the age when the injury was inflicted. The present study examines whether brains injured at different developmental stages may acquire different susceptibility to experimental status epilepticus induced in adulthood. In 6- and 30-day-old Wistar rats (P6s and P30s, respectively), a mechanical injury was performed in the left cerebral hemisphere. On postnatal day 60, all the animals and controls received single injections of kainic acid to evoke status epilepticus. During a 6-h period following the injection, the animals were observed continuously and motor symptoms of seizure activity were recorded and rated. P6s showed significantly lower intensity of kainic acid-induced epileptic symptoms and significantly longer survival than controls or P30s. In P30s, no significant change was detected. The data provide evidence that the developmental stage when the brain is injured determines epileptogenecity of the lesion. However, a considerable discrepancy between these data and those obtained previously following pilocarpine administration in the same experimental models of brain injury shows that each of the two models of epilepsy may display different aspects of the same age-dependent process triggered by the brain injury.
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Affiliation(s)
- Zuzanna Setkowicz
- Department of Neuroanatomy, Institute of Zoology, Jagiellonian University, 6 Ingardena St., 30 060 Kraków, Poland
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Witgen BM, Lifshitz J, Smith ML, Schwarzbach E, Liang SL, Grady MS, Cohen AS. Regional hippocampal alteration associated with cognitive deficit following experimental brain injury: a systems, network and cellular evaluation. Neuroscience 2005; 133:1-15. [PMID: 15893627 DOI: 10.1016/j.neuroscience.2005.01.052] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2004] [Revised: 12/10/2004] [Accepted: 01/17/2005] [Indexed: 10/25/2022]
Abstract
Cognitive deficits persist in patients who survive traumatic brain injury (TBI). Lateral fluid percussion brain injury in the mouse, a model of human TBI, results in hippocampal-dependent cognitive impairment, similar to retrograde amnesia often associated with TBI. To identify potential substrates of the cognitive impairment, we evaluated regional neuronal loss, regional hippocampal excitability and inhibitory synaptic transmission. Design-based stereology demonstrated an approximate 40% loss of neurons through all subregions of the hippocampus following injury compared with sham. Input/output curves recorded in slices of injured brain demonstrated increased net synaptic efficacy in the dentate gyrus in concert with decreased net synaptic efficacy and excitatory postsynaptic potential-spike relationship in area CA1 compared with sham slices. Pharmacological agents modulating inhibitory transmission partially restored regional injury-induced alterations in net synaptic efficacy. Both evoked and spontaneous miniature inhibitory postsynaptic currents (mIPSCs) recorded in surviving dentate granule neurons were smaller and less frequent in injured brains than in uninjured brains. Conversely, both evoked and spontaneous mIPSCs recorded in surviving area CA1 pyramidal neurons were larger in injured brains than in uninjured brains. Together, these alterations suggest that regional hippocampal function is altered in the injured brain. This study demonstrates for the first time that brain injury selectively disrupts hippocampal function by causing uniform neuronal loss, inhibitory synaptic dysfunction, and regional, but opposing, shifts in circuit excitability. These changes may contribute to the cognitive impairments that result from brain injury.
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Affiliation(s)
- B M Witgen
- Department of Neurosurgery, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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Thompson HJ, Lifshitz J, Marklund N, Grady MS, Graham DI, Hovda DA, McIntosh TK. Lateral fluid percussion brain injury: a 15-year review and evaluation. J Neurotrauma 2005; 22:42-75. [PMID: 15665602 DOI: 10.1089/neu.2005.22.42] [Citation(s) in RCA: 338] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
This article comprehensively reviews the lateral fluid percussion (LFP) model of traumatic brain injury (TBI) in small animal species with particular emphasis on its validity, clinical relevance and reliability. The LFP model, initially described in 1989, has become the most extensively utilized animal model of TBI (to date, 232 PubMed citations), producing both focal and diffuse (mixed) brain injury. Despite subtle variations in injury parameters between laboratories, universal findings are evident across studies, including histological, physiological, metabolic, and behavioral changes that serve to increase the reliability of the model. Moreover, demonstrable histological damage and severity-dependent behavioral deficits, which partially recover over time, validate LFP as a clinically-relevant model of human TBI. The LFP model, also has been used extensively to evaluate potential therapeutic interventions, including resuscitation, pharmacologic therapies, transplantation, and other neuroprotective and neuroregenerative strategies. Although a number of positive studies have identified promising therapies for moderate TBI, the predictive validity of the model may be compromised when findings are translated to severely injured patients. Recently, the clinical relevance of LFP has been enhanced by combining the injury with secondary insults, as well as broadening studies to incorporate issues of gender and age to better approximate the range of human TBI within study design. We conclude that the LFP brain injury model is an appropriate tool to study the cellular and mechanistic aspects of human TBI that cannot be addressed in the clinical setting, as well as for the development and characterization of novel therapeutic interventions. Continued translation of pre-clinical findings to human TBI will enhance the predictive validity of the LFP model, and allow novel neuroprotective and neuroregenerative treatment strategies developed in the laboratory to reach the appropriate TBI patients.
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Affiliation(s)
- Hilaire J Thompson
- Traumatic Brain Injury Laboratory, Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Delorenzo RJ, Sun DA, Deshpande LS. Cellular mechanisms underlying acquired epilepsy: the calcium hypothesis of the induction and maintainance of epilepsy. Pharmacol Ther 2005; 105:229-66. [PMID: 15737406 PMCID: PMC2819430 DOI: 10.1016/j.pharmthera.2004.10.004] [Citation(s) in RCA: 196] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2004] [Accepted: 10/12/2004] [Indexed: 01/22/2023]
Abstract
Epilepsy is one of the most common neurological disorders. Although epilepsy can be idiopathic, it is estimated that up to 50% of all epilepsy cases are initiated by neurological insults and are called acquired epilepsy (AE). AE develops in 3 phases: (1) the injury (central nervous system [CNS] insult), (2) epileptogenesis (latency), and (3) the chronic epileptic (spontaneous recurrent seizure) phases. Status epilepticus (SE), stroke, and traumatic brain injury (TBI) are 3 major examples of common brain injuries that can lead to the development of AE. It is especially important to understand the molecular mechanisms that cause AE because it may lead to innovative strategies to prevent or cure this common condition. Recent studies have offered new insights into the cause of AE and indicate that injury-induced alterations in intracellular calcium concentration levels [Ca(2+)](i) and calcium homeostatic mechanisms play a role in the development and maintenance of AE. The injuries that cause AE are different, but they share a common molecular mechanism for producing brain damage-an increase in extracellular glutamate concentration that causes increased intracellular neuronal calcium, leading to neuronal injury and/or death. Neurons that survive the injury induced by glutamate and are exposed to increased [Ca(2+)](i) are the cellular substrates to develop epilepsy because dead cells do not seize. The neurons that survive injury sustain permanent long-term plasticity changes in [Ca(2+)](i) and calcium homeostatic mechanisms that are permanent and are a prominent feature of the epileptic phenotype. In the last several years, evidence has accumulated indicating that the prolonged alteration in neuronal calcium dynamics plays an important role in the induction and maintenance of the prolonged neuroplasticity changes underlying the epileptic phenotype. Understanding the role of calcium as a second messenger in the induction and maintenance of epilepsy may provide novel insights into therapeutic advances that will prevent and even cure AE.
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Affiliation(s)
- Robert J Delorenzo
- Department of Neurology, Virginia Commonwealth University, School of Medicine, Richmond, VA 23298-0599, USA.
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