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Löscher W, White HS. Animal Models of Drug-Resistant Epilepsy as Tools for Deciphering the Cellular and Molecular Mechanisms of Pharmacoresistance and Discovering More Effective Treatments. Cells 2023; 12:cells12091233. [PMID: 37174633 PMCID: PMC10177106 DOI: 10.3390/cells12091233] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 02/28/2023] [Accepted: 04/18/2023] [Indexed: 05/15/2023] Open
Abstract
In the last 30 years, over 20 new anti-seizure medicines (ASMs) have been introduced into the market for the treatment of epilepsy using well-established preclinical seizure and epilepsy models. Despite this success, approximately 20-30% of patients with epilepsy have drug-resistant epilepsy (DRE). The current approach to ASM discovery for DRE relies largely on drug testing in various preclinical model systems that display varying degrees of ASM drug resistance. In recent years, attempts have been made to include more etiologically relevant models in the preclinical evaluation of a new investigational drug. Such models have played an important role in advancing a greater understanding of DRE at a mechanistic level and for hypothesis testing as new experimental evidence becomes available. This review provides a critical discussion of the pharmacology of models of adult focal epilepsy that allow for the selection of ASM responders and nonresponders and those models that display a pharmacoresistance per se to two or more ASMs. In addition, the pharmacology of animal models of major genetic epilepsies is discussed. Importantly, in addition to testing chemical compounds, several of the models discussed here can be used to evaluate other potential therapies for epilepsy such as neurostimulation, dietary treatments, gene therapy, or cell transplantation. This review also discusses the challenges associated with identifying novel therapies in the absence of a greater understanding of the mechanisms that contribute to DRE. Finally, this review discusses the lessons learned from the profile of the recently approved highly efficacious and broad-spectrum ASM cenobamate.
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Affiliation(s)
- Wolfgang Löscher
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine, Bünteweg 17, 30559 Hannover, Germany
- Center for Systems Neuroscience, 30559 Hannover, Germany
| | - H Steve White
- Department of Pharmacy, School of Pharmacy, University of Washington, Seattle, WA 98195, USA
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2
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Rawat V, Eastman CL, Amaradhi R, Banik A, Fender JS, Dingledine RJ, D’Ambrosio R, Ganesh T. Temporal Expression of Neuroinflammatory and Oxidative Stress Markers and Prostaglandin E2 Receptor EP2 Antagonist Effect in a Rat Model of Epileptogenesis. ACS Pharmacol Transl Sci 2022; 6:128-138. [PMID: 36654746 PMCID: PMC9841781 DOI: 10.1021/acsptsci.2c00189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Indexed: 12/13/2022]
Abstract
Traumatic brain injury (TBI) in patients results in a massive inflammatory reaction, disruption of blood-brain barrier, and oxidative stress in the brain, and these inciting features may culminate in the emergence of post-traumatic epilepsy (PTE). We hypothesize that targeting these pathways with pharmacological agents could be an effective therapeutic strategy to prevent epileptogenesis. To design therapeutic strategies targeting neuroinflammation and oxidative stress, we utilized a fluid percussion injury (FPI) rat model to study the temporal expression of neuroinflammatory and oxidative stress markers from 3 to 24 h following FPI. FPI results in increased mRNA expression of inflammatory mediators including cyclooxygenase-2 (COX-2) and prostanoid receptor EP2, marker of oxidative stress (NOX2), astrogliosis (GFAP), and microgliosis (CD11b) in ipsilateral cortex and hippocampus. The analysis of protein levels indicated a significant increase in the expression of COX-2 in ipsilateral hippocampus and cortex post-FPI. We tested FPI rats with an EP2 antagonist TG8-260 which produced a statistically significant reduction in the distribution of seizure duration post-FPI and trends toward a reduction in seizure incidence, seizure frequency, and duration, hinting a proof of concept that EP2 antagonism must be further optimized for therapeutic applications to prevent epileptogenesis.
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Affiliation(s)
- Varun Rawat
- Department
of Pharmacology and Chemical Biology, Emory
University School of Medicine, Atlanta, Georgia 30322, United States
| | - Clifford L. Eastman
- Department
of Neurological Surgery, University of Washington, 325 Ninth Avenue, Seattle, Washington 98104, United States
| | - Radhika Amaradhi
- Department
of Pharmacology and Chemical Biology, Emory
University School of Medicine, Atlanta, Georgia 30322, United States
| | - Avijit Banik
- Department
of Pharmacology and Chemical Biology, Emory
University School of Medicine, Atlanta, Georgia 30322, United States
| | - Jason S. Fender
- Department
of Neurological Surgery, University of Washington, 325 Ninth Avenue, Seattle, Washington 98104, United States
| | - Raymond J. Dingledine
- Department
of Pharmacology and Chemical Biology, Emory
University School of Medicine, Atlanta, Georgia 30322, United States
| | - Raimondo D’Ambrosio
- Department
of Neurological Surgery, University of Washington, 325 Ninth Avenue, Seattle, Washington 98104, United States,Regional
Epilepsy Center, University of Washington, 325 Ninth Avenue, Seattle, Washington 98104, United States
| | - Thota Ganesh
- Department
of Pharmacology and Chemical Biology, Emory
University School of Medicine, Atlanta, Georgia 30322, United States,. Phone: 404-727-7393. Fax: 404-727-0365
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3
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Eastman CL, Fender JS, Klein P, D'Ambrosio R. Therapeutic Effects of Time-Limited Treatment with Brivaracetam on Posttraumatic Epilepsy after Fluid Percussion Injury in the Rat. J Pharmacol Exp Ther 2021; 379:310-323. [PMID: 34593559 DOI: 10.1124/jpet.121.000585] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 09/28/2021] [Indexed: 11/22/2022] Open
Abstract
Mounting evidence suggests the synaptic vesicle glycoprotein 2A (SV2A) targeted by levetiracetam may contribute to epileptogenesis. Levetiracetam has shown anti-inflammatory, antioxidant, neuroprotective, and possible antiepileptogenic effects in brain injury and seizure/epilepsy models, and a phase 2 study has signaled a possible clinical antiepileptogenic effect. Brivaracetam shows greater affinity and specificity for SV2A than levetiracetam and broader preclinical antiseizure effects. Thus, we assessed the antiepileptogenic/disease-modifying potential of brivaracetam in an etiologically realistic rat posttraumatic epilepsy model optimized for efficient drug testing. Brivaracetam delivery protocols were designed to maintain clinical moderate-to-high plasma levels in young (5-week-old) male Sprague-Dawley rats for 4 weeks. Treatment protocols were rapidly screened in 4-week experiments using small groups of animals to ensure against rigorous testing of futile treatment protocols. The antiepileptogenic effects of brivaracetam treatment initiated 30 minutes, 4 hours, and 8 hours after rostral parasagittal fluid percussion injury (rpFPI) were then compared with vehicle-treated controls in a fully powered blind and randomized 16-week validation. Seizures were evaluated by video-electrocorticography using a 5-electrode epidural montage. Endpoint measures included incidence, frequency, duration, and spread of seizures. Group sizes and recording durations were supported by published power analyses. Three months after treatment ended, rats treated with brivaracetam starting at 4 hours post-FPI (the best-performing protocol) experienced a 38% decrease in overall incidence of seizures, 59% decrease in seizure frequency, 67% decrease in time spent seizing, and a 45% decrease in the proportion of spreading seizures that was independent of duration-based seizure definition. Thus, brivaracetam shows both antiepileptogenic and disease-modifying properties after rpFPI. SIGNIFICANCE STATEMENT: The rpFPI model, which likely incorporates epileptogenic mechanisms operating after human head injury, can be used to efficiently screen investigational treatment protocols and assess antiepileptogenic/disease-modifying effects. Our studies 1) support a role for SV2A in epileptogenesis, 2) suggest that brivaracetam and other drugs targeting SV2A should be considered for human clinical trials of prevention of post-traumatic epilepsy after head injury, and 3) provide data to inform the design of treatment protocols for clinical trials.
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Affiliation(s)
- Clifford L Eastman
- Department of Neurological Surgery, University of Washington, Seattle, Washington (C.L.E., J.S.F., R.D.); and Mid-Atlantic Epilepsy and Sleep Center, Bethesda, Maryland (P.K.)
| | - Jason S Fender
- Department of Neurological Surgery, University of Washington, Seattle, Washington (C.L.E., J.S.F., R.D.); and Mid-Atlantic Epilepsy and Sleep Center, Bethesda, Maryland (P.K.)
| | - Pavel Klein
- Department of Neurological Surgery, University of Washington, Seattle, Washington (C.L.E., J.S.F., R.D.); and Mid-Atlantic Epilepsy and Sleep Center, Bethesda, Maryland (P.K.)
| | - Raimondo D'Ambrosio
- Department of Neurological Surgery, University of Washington, Seattle, Washington (C.L.E., J.S.F., R.D.); and Mid-Atlantic Epilepsy and Sleep Center, Bethesda, Maryland (P.K.)
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Bertram EH, Edelbroek P. Chronic limbic epilepsy models for therapy discovery: Protocols to improve efficiency. Epilepsia 2021; 62:2252-2262. [PMID: 34289109 DOI: 10.1111/epi.16995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 06/23/2020] [Indexed: 11/28/2022]
Abstract
OBJECTIVE There have been recommendations to improve therapy discovery for epilepsy by incorporating chronic epilepsy models into the preclinical process, but unpredictable seizures and difficulties in maintaining drug levels over prolonged periods have been obstacles to using these animals. We report new protocols in which drugs are administered through a new chronic gastric tube to rats with higher seizure frequencies to minimize these obstacles. METHODS Adult rats with spontaneous limbic seizures following an episode of limbic status epilepticus induced by electrical hippocampal stimulation were monitored with long-term video- electroencephalography (EEG). Animals with a predetermined baseline seizure frequency received an intragastric tube for drug administration. Carbamazepine, levetiracetam, phenobarbital, and phenytoin were tested with either an acute protocol (an increasing single dose every other day for a maximum of three doses) or with a chronic protocol (multiple administrations of one dose for a week). Drug levels were obtained to correlate the effect with the level. RESULTS With the acute protocol, all four drugs induced a clear dose-related response. Similar dose-related responses were seen following the week-long dosing protocol for carbamazepine, phenobarbital, and phenytoin, and these responses were associated with drug levels that were in the human therapeutic range. The response to chronic levetiracetam was much less robust. The gastric tube route of administration was well tolerated over a number of months. SIGNIFICANCE Using rats with stable, higher seizure frequencies made it possible to identify the potential of a drug to suppress seizures in a realistic model of epilepsy with drug levels that are similar to those of human therapeutic levels. The acute protocol provided a full dose response in 1 week. The chronic administration protocol further differentiated drugs that may be effective long term. The gastric tube facilitates a less stressful, humane, and consistent administration of multiple doses.
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Affiliation(s)
- Edward H Bertram
- Department of Neurology, University of Virginia, Charlottesville, VA, USA
| | - Peter Edelbroek
- SEIN: Epilepsy Institute in the Netherlands Foundation Heemstede, Heemstede, The Netherlands
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5
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Galanopoulou AS, Löscher W, Lubbers L, O’Brien TJ, Staley K, Vezzani A, D’Ambrosio R, White HS, Sontheimer H, Wolf JA, Twyman R, Whittemore V, Wilcox KS, Klein B. Antiepileptogenesis and disease modification: Progress, challenges, and the path forward-Report of the Preclinical Working Group of the 2018 NINDS-sponsored antiepileptogenesis and disease modification workshop. Epilepsia Open 2021; 6:276-296. [PMID: 34033232 PMCID: PMC8166793 DOI: 10.1002/epi4.12490] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 04/04/2021] [Accepted: 04/12/2021] [Indexed: 12/12/2022] Open
Abstract
Epilepsy is one of the most common chronic brain diseases and is often associated with cognitive, behavioral, or other medical conditions. The need for therapies that would prevent, ameliorate, or cure epilepsy and the attendant comorbidities is a priority for both epilepsy research and public health. In 2018, the National Institute of Neurological Disease and Stroke (NINDS) convened a workshop titled "Accelerating the Development of Therapies for Antiepileptogenesis and Disease Modification" that brought together preclinical and clinical investigators and industry and regulatory bodies' representatives to discuss and propose a roadmap to accelerate the development of antiepileptogenic (AEG) and disease-modifying (DM) new therapies. This report provides a summary of the discussions and proposals of the Preclinical Science working group. Highlights of the progress of collaborative preclinical research projects on AEG/DM of ongoing research initiatives aiming to improve infrastructure and translation to clinical trials are presented. Opportunities and challenges of preclinical epilepsy research, vis-à-vis clinical research, were extensively discussed, as they pertain to modeling of specific epilepsy types across etiologies and ages, the utilization of preclinical models in AG/DM studies, and the strategies and study designs, as well as on matters pertaining to transparency, data sharing, and reporting research findings. A set of suggestions on research initiatives, infrastructure, workshops, advocacy, and opportunities for expanding the borders of epilepsy research were discussed and proposed as useful initiatives that could help create a roadmap to accelerate and optimize preclinical translational AEG/DM epilepsy research.
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Affiliation(s)
- Aristea S. Galanopoulou
- Saul R. Korey Department of NeurologyDominick P. Purpura Department of NeuroscienceIsabelle Rapin Division of Child NeurologyAlbert Einstein College of MedicineBronxNYUSA
| | - Wolfgang Löscher
- Department of Pharmacology, Toxicology, and PharmacyUniversity of Veterinary Medicine HannoverHannoverGermany
| | | | - Terence J. O’Brien
- Department of NeuroscienceCentral Clinical SchoolAlfred HealthMonash UniversityMelbourneVic.Australia
| | - Kevin Staley
- Department of NeurologyMassachusetts General HospitalBostonMAUSA
| | - Annamaria Vezzani
- Department of NeuroscienceIRCCS‐Mario Negri Institute for Pharmacological ResearchMilanoItaly
| | | | - H. Steve White
- Department of PharmacySchool of PharmacyUniversity of WashingtonSeattleWAUSA
| | | | - John A. Wolf
- Center for Brain Injury and RepairDepartment of NeurosurgeryUniversity of PennsylvaniaPhiladelphiaPAUSA
- Corporal Michael J. Crescenz Veterans Affairs Medical CenterPhiladelphiaPAUSA
| | | | - Vicky Whittemore
- National Institute of Neurological Disorders and StrokeNational Institutes of HealthBethesdaMDUSA
| | - Karen S. Wilcox
- Department of Pharmacology & ToxicologyUniversity of UtahSalt Lake CityUTUSA
| | - Brian Klein
- National Institute of Neurological Disorders and StrokeNational Institutes of HealthBethesdaMDUSA
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6
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Tatum S, Smith ZZ, Taylor JA, Poulsen DJ, Dudek FE, Barth DS. Sensitivity of unilateral- versus bilateral-onset spike-wave discharges to ethosuximide and carbamazepine in the fluid percussion injury rat model of traumatic brain injury. J Neurophysiol 2021; 125:2166-2177. [PMID: 33949882 DOI: 10.1152/jn.00098.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Unilateral-onset spike-wave discharges (SWDs) following fluid percussion injury (FPI) in rats have been used for nearly two decades as a model for complex partial seizures in human posttraumatic epilepsy (PTE). This study determined if SWDs with a unilateral versus bilateral cortical onset differed. In this experiment, 2-mo-old rats received severe FPI (3 atm) or sham surgery and were instrumented for chronic video-electrocorticography (ECoG) recording (up to 9 mo). The antiseizure drug, carbamazepine (CBZ), and the antiabsence drug, ethosuximide (ETX), were administered separately to determine if they selectively suppressed unilateral- versus bilateral-onset SWDs, respectively. SWDs did not significantly differ between FPI and sham rats on any measured parameter (wave-shape, frequency spectrum, duration, or age-related progression), including unilateral (∼17%) versus bilateral (∼83%) onsets. SWDs with a unilateral onset preferentially originated ipsilateral to the craniotomy in both FPI and sham rats, suggesting that the unilateral-onset SWDs were related to surgical injury and not specifically to FPI. ETX profoundly suppressed SWDs with either unilateral or bilateral onsets, and CBZ had no effect on either type of SWD. These results suggest that SWDs with either a unilateral or bilateral onset have a pharmacosensitivity similar to absence seizures and are very different from the complex partial seizures of PTE. Therefore, SWDs with a unilateral onset after FPI are not a model of the complex partial seizures that occur in PTE, and their use for finding new treatments for PTE could be counterproductive, particularly if their close similarity to normal brain oscillations is not acknowledged.NEW & NOTEWORTHY Unilateral-onset spike-wave discharges (SWDs) in rats have been used to model complex partial seizures in human posttraumatic epilepsy (PTE), compared to bilateral-onset SWDs thought to reflect human absence seizures. Here, we show that both unilateral- and bilateral-onset SWDs following traumatic brain injury are suppressed by the antiabsence drug ethosuximide and are unaffected by the antiseizure drug carbamazepine. We propose that unilateral-onset SWDs are not useful for studying mechanisms of, or treatments for, PTE.
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Affiliation(s)
- Sean Tatum
- Department of Psychology and Neuroscience, University of Colorado, Boulder, Colorado
| | - Zachariah Z Smith
- Department of Psychology and Neuroscience, University of Colorado, Boulder, Colorado
| | - Jeremy A Taylor
- Department of Psychology and Neuroscience, University of Colorado, Boulder, Colorado
| | - David J Poulsen
- Department of Neurosurgery, University at Buffalo Jacob's School of Medicine and Biomedical Sciences, Buffalo, New York
| | - F Edward Dudek
- Department of Neurosurgery, University of Utah School of Medicine, Salt Lake City, Utah
| | - Daniel S Barth
- Department of Psychology and Neuroscience, University of Colorado, Boulder, Colorado
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7
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Löscher W. The holy grail of epilepsy prevention: Preclinical approaches to antiepileptogenic treatments. Neuropharmacology 2019; 167:107605. [PMID: 30980836 DOI: 10.1016/j.neuropharm.2019.04.011] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 04/03/2019] [Accepted: 04/09/2019] [Indexed: 02/06/2023]
Abstract
A variety of acute brain insults can induce epileptogenesis, a complex process that results in acquired epilepsy. Despite advances in understanding mechanisms of epileptogenesis, there is currently no approved treatment that prevents the development or progression of epilepsy in patients at risk. The current concept of epileptogenesis assumes a window of opportunity following acute brain insults that allows intervention with preventive treatment. Recent results suggest that injury-induced epileptogenesis can be a much more rapid process than previously thought, suggesting that the 'therapeutic window' may only be open for a brief period, as in stroke therapy. However, experimental data also suggest a second, possibly delayed process ("secondary epileptogenesis") that influences the progression and refractoriness of the epileptic state over time, allowing interfering with this process even after onset of epilepsy. In this review, both methodological issues in preclinical drug development and novel targets for antiepileptogenesis will be discussed. Several promising drugs that either prevent epilepsy (antiepileptogenesis) or slow epilepsy progression and alleviate cognitive or behavioral comorbidities of epilepsy (disease modification) have been described in recent years, using diverse animal models of acquired epilepsy. Promising agents include TrkB inhibitors, losartan, statins, isoflurane, anti-inflammatory and anti-oxidative drugs, the SV2A modulator levetiracetam, and epigenetic interventions. Research on translational target validity and on prognostic biomarkers that can be used to stratify patients (or experimental animals) at high risk of developing epilepsy will hopefully soon lead to proof-of-concept clinical trials with the most promising drugs, which will be essential to make prevention of epilepsy a reality. This article is part of the special issue entitled 'New Epilepsy Therapies for the 21st Century - From Antiseizure Drugs to Prevention, Modification and Cure of Epilepsy'.
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Affiliation(s)
- Wolfgang Löscher
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine, Hannover, Germany; Center for Systems Neuroscience, Hannover, Germany.
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8
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Smith D, Rau T, Poulsen A, MacWilliams Z, Patterson D, Kelly W, Poulsen D. Convulsive seizures and EEG spikes after lateral fluid-percussion injury in the rat. Epilepsy Res 2018; 147:87-94. [PMID: 30286390 DOI: 10.1016/j.eplepsyres.2018.09.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 08/29/2018] [Accepted: 09/14/2018] [Indexed: 10/28/2022]
Abstract
The rat lateral fluid-percussion injury (FPI) model has been used extensively to study post-traumatic epilepsy (PTE). Epidemiological studies have reported that the risk of PTE is higher after more severe injury. Adult, male Wistar rats subjected to different atmospheric pressures of injury during FPI showed great variability in injury severity when functional behavior was determined based on the Neurological Severity Score (NSS) assessment. When NSS was used to select rats with the most severe FPI-induced brain injury, 63% of rats experienced at least one convulsive seizure 2-5 weeks after FPI. This same cohort of rats (i.e., selected for severe TBI based on NSS) were significantly more susceptible to PTZ-induced seizures compared to sham controls. Video/EEG recordings from a second cohort of rats with severe FPI-induced injury (based on NSS) showed a similar incidence and frequency of spike wave discharges between rats with severe TBI and sham controls. However, the rate of isolated EEG spikes was greater in rats with severe FPI-induced injury compared to sham controls. These data suggest that convulsive seizures can be obtained in FPI-treated rats when NSS is used as an inclusion criterion to select rats with severe injury. Furthermore, although spike-wave discharges were equally prevalent in rats with severe FPI and sham controls, spontaneous spikes were more prevalent in the rats with severe FPI.
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Affiliation(s)
- Debbie Smith
- University of Montana, Department of Biomedical and Pharmaceutical Sciences, Missoula, MT, United States
| | - Thomas Rau
- University of Montana, Department of Biomedical and Pharmaceutical Sciences, Missoula, MT, United States
| | - Austin Poulsen
- University of Montana, Department of Biomedical and Pharmaceutical Sciences, Missoula, MT, United States
| | - Ziven MacWilliams
- University of Montana, Department of Biomedical and Pharmaceutical Sciences, Missoula, MT, United States
| | - David Patterson
- University of Montana, Department of Mathematics, Missoula, MT, United States
| | - William Kelly
- University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Department of Neurosurgery, Buffalo, NY, United States
| | - David Poulsen
- University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Department of Neurosurgery, Buffalo, NY, United States.
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9
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Smith ZZ, Benison AM, Bercum FM, Dudek FE, Barth DS. Progression of convulsive and nonconvulsive seizures during epileptogenesis after pilocarpine-induced status epilepticus. J Neurophysiol 2018; 119:1818-1835. [PMID: 29442558 DOI: 10.1152/jn.00721.2017] [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: 11/22/2022] Open
Abstract
Although convulsive seizures occurring during pilocarpine-induced epileptogenesis have received considerable attention, nonconvulsive seizures have not been closely examined, even though they may reflect the earliest signs of epileptogenesis and potentially guide research on antiepileptogenic interventions. The definition of nonconvulsive seizures based on brain electrical activity alone has been controversial. Here we define and quantify electrographic properties of convulsive and nonconvulsive seizures in the context of the acquired epileptogenesis that occurs after pilocarpine-induced status epilepticus (SE). Lithium-pilocarpine was used to induce the prolonged repetitive seizures characteristic of SE; when SE was terminated with paraldehyde, seizures returned during the 2-day period after pilocarpine treatment. A distinct latent period ranging from several days to >2 wk was then measured with continuous, long-term video-EEG. Nonconvulsive seizures dominated the onset of epileptogenesis and consistently preceded the first convulsive seizures but were still present later. Convulsive and nonconvulsive seizures had similar durations. Postictal depression (background suppression of the EEG) lasted for >100 s after both convulsive and nonconvulsive seizures. Principal component analysis was used to quantify the spectral evolution of electrical activity that characterized both types of spontaneous recurrent seizures. These studies demonstrate that spontaneous nonconvulsive seizures have electrographic properties similar to convulsive seizures and confirm that nonconvulsive seizures link the latent period and the onset of convulsive seizures during post-SE epileptogenesis in an animal model. Nonconvulsive seizures may also reflect the earliest signs of epileptogenesis in human acquired epilepsy, when intervention could be most effective. NEW & NOTEWORTHY Nonconvulsive seizures usually represent the first bona fide seizure following a latent period, dominate the early stages of epileptogenesis, and change in severity in a manner consistent with the progressive nature of epileptogenesis. This analysis demonstrates that nonconvulsive and convulsive seizures have different behavioral outcomes but similar electrographic signatures. Alternatively, epileptiform spike-wave discharges fail to recapitulate several key seizure features and represent a category of electrical activity separate from nonconvulsive seizures in this model.
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Affiliation(s)
- Zachariah Z Smith
- Department of Psychology and Neuroscience, University of Colorado , Boulder, Colorado
| | - Alexander M Benison
- Department of Psychology and Neuroscience, University of Colorado , Boulder, Colorado
| | - Florencia M Bercum
- Department of Psychology and Neuroscience, University of Colorado , Boulder, Colorado
| | - F Edward Dudek
- Department of Neurosurgery, University of Utah School of Medicine , Salt Lake City, Utah
| | - Daniel S Barth
- Department of Psychology and Neuroscience, University of Colorado , Boulder, Colorado
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10
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Klein P, Dingledine R, Aronica E, Bernard C, Blümcke I, Boison D, Brodie MJ, Brooks-Kayal AR, Engel J, Forcelli PA, Hirsch LJ, Kaminski RM, Klitgaard H, Kobow K, Lowenstein DH, Pearl PL, Pitkänen A, Puhakka N, Rogawski MA, Schmidt D, Sillanpää M, Sloviter RS, Steinhäuser C, Vezzani A, Walker MC, Löscher W. Commonalities in epileptogenic processes from different acute brain insults: Do they translate? Epilepsia 2018; 59:37-66. [PMID: 29247482 PMCID: PMC5993212 DOI: 10.1111/epi.13965] [Citation(s) in RCA: 185] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/01/2017] [Indexed: 12/12/2022]
Abstract
The most common forms of acquired epilepsies arise following acute brain insults such as traumatic brain injury, stroke, or central nervous system infections. Treatment is effective for only 60%-70% of patients and remains symptomatic despite decades of effort to develop epilepsy prevention therapies. Recent preclinical efforts are focused on likely primary drivers of epileptogenesis, namely inflammation, neuron loss, plasticity, and circuit reorganization. This review suggests a path to identify neuronal and molecular targets for clinical testing of specific hypotheses about epileptogenesis and its prevention or modification. Acquired human epilepsies with different etiologies share some features with animal models. We identify these commonalities and discuss their relevance to the development of successful epilepsy prevention or disease modification strategies. Risk factors for developing epilepsy that appear common to multiple acute injury etiologies include intracranial bleeding, disruption of the blood-brain barrier, more severe injury, and early seizures within 1 week of injury. In diverse human epilepsies and animal models, seizures appear to propagate within a limbic or thalamocortical/corticocortical network. Common histopathologic features of epilepsy of diverse and mostly focal origin are microglial activation and astrogliosis, heterotopic neurons in the white matter, loss of neurons, and the presence of inflammatory cellular infiltrates. Astrocytes exhibit smaller K+ conductances and lose gap junction coupling in many animal models as well as in sclerotic hippocampi from temporal lobe epilepsy patients. There is increasing evidence that epilepsy can be prevented or aborted in preclinical animal models of acquired epilepsy by interfering with processes that appear common to multiple acute injury etiologies, for example, in post-status epilepticus models of focal epilepsy by transient treatment with a trkB/PLCγ1 inhibitor, isoflurane, or HMGB1 antibodies and by topical administration of adenosine, in the cortical fluid percussion injury model by focal cooling, and in the albumin posttraumatic epilepsy model by losartan. Preclinical studies further highlight the roles of mTOR1 pathways, JAK-STAT3, IL-1R/TLR4 signaling, and other inflammatory pathways in the genesis or modulation of epilepsy after brain injury. The wealth of commonalities, diversity of molecular targets identified preclinically, and likely multidimensional nature of epileptogenesis argue for a combinatorial strategy in prevention therapy. Going forward, the identification of impending epilepsy biomarkers to allow better patient selection, together with better alignment with multisite preclinical trials in animal models, should guide the clinical testing of new hypotheses for epileptogenesis and its prevention.
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Affiliation(s)
- Pavel Klein
- Mid-Atlantic Epilepsy and Sleep Center, Bethesda, MD, USA
| | | | - Eleonora Aronica
- Department of (Neuro) Pathology, Academic Medical Center and Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, The Netherlands
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, The Netherlands
| | - Christophe Bernard
- Aix Marseille Univ, Inserm, INS, Instit Neurosci Syst, Marseille, 13005, France
| | - Ingmar Blümcke
- Department of Neuropathology, University Hospital Erlangen, Erlangen, Germany
| | - Detlev Boison
- Robert Stone Dow Neurobiology Laboratories, Legacy Research Institute, Portland, OR, USA
| | - Martin J Brodie
- Epilepsy Unit, West Glasgow Ambulatory Care Hospital-Yorkhill, Glasgow, UK
| | - Amy R Brooks-Kayal
- Division of Neurology, Departments of Pediatrics and Neurology, University of Colorado School of Medicine, Aurora, CO, USA
- Children's Hospital Colorado, Aurora, CO, USA
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Jerome Engel
- Departments of Neurology, Neurobiology, and Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, Brain Research Institute, University of California, Los Angeles, CA, USA
| | | | | | | | | | - Katja Kobow
- Department of Neuropathology, University Hospital Erlangen, Erlangen, Germany
| | | | - Phillip L Pearl
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Asla Pitkänen
- Department of Neurobiology, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Noora Puhakka
- Department of Neurobiology, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Michael A Rogawski
- Department of Neurology, University of California, Davis, Sacramento, CA, USA
| | | | - Matti Sillanpää
- Departments of Child Neurology and General Practice, University of Turku and Turku University Hospital, Turku, Finland
| | - Robert S Sloviter
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA, USA
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Annamaria Vezzani
- Department of Neuroscience, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Institute for Pharmacological Research, Milan,, Italy
| | - Matthew C Walker
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK
| | - Wolfgang Löscher
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine, Hannover, Germany
- Center for Systems Neuroscience, Hannover, Germany
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11
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Dunn R, Queenan BN, Pak DTS, Forcelli PA. Divergent effects of levetiracetam and tiagabine against spontaneous seizures in adult rats following neonatal hypoxia. Epilepsy Res 2017; 140:1-7. [PMID: 29227795 DOI: 10.1016/j.eplepsyres.2017.12.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Revised: 10/09/2017] [Accepted: 12/02/2017] [Indexed: 01/03/2023]
Abstract
Animal models are valuable tools for screening novel therapies for patients who suffer from epilepsy. However, a wide array of models are necessary to cover the diversity of human epilepsies. In humans, neonatal hypoxia (or hypoxia-ischemia) is one of the most common causes of epilepsy early in life. Hypoxia-induced seizures (HS) during the neonatal period can also lead to spontaneous seizures in adulthood. This phenomenon, i.e., early-life hypoxia leading to adult epilepsy - is also seen in experimental models, including rats. However, it is not known which anti-seizure medications are most effective at managing adult epilepsy resulting from neonatal HS. Here, we examined the efficacy of three anti-seizure medications against spontaneous seizures in adult rats with a history of neonatal HS: (1) phenobarbital (PHB), the oldest epilepsy medicine still in use today; (2) levetiracetam (LEV); and (3) tiagabine (TGB). Both LEV and TGB are relatively new anticonvulsant drugs that are ineffective in traditional seizure models, but strikingly effective in other models. We found that PHB and LEV decreased seizures in adult rats with a history of HS, whereas TGB exacerbated seizures. These divergent drug effects indicate that the HS model may be useful for differentiating the clinical efficacy of putative epilepsy therapies.
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Affiliation(s)
- Raymond Dunn
- Department of Pharmacology and Physiology, United States
| | - Bridget N Queenan
- Department of Pharmacology and Physiology, United States; Interdisciplinary Program in Neuroscience, Georgetown University, Washington DC, United States; Neuroscience Research Institute, Department of Mechanical Engineering; Department of Physics, University sof California, Santa Barbara, Santa Barbara, CA, United States
| | - Daniel T S Pak
- Department of Pharmacology and Physiology, United States; Interdisciplinary Program in Neuroscience, Georgetown University, Washington DC, United States.
| | - Patrick A Forcelli
- Department of Pharmacology and Physiology, United States; Department of Neuroscience, United States; Interdisciplinary Program in Neuroscience, Georgetown University, Washington DC, United States.
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12
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Kadam SD, D'Ambrosio R, Duveau V, Roucard C, Garcia-Cairasco N, Ikeda A, de Curtis M, Galanopoulou AS, Kelly KM. Methodological standards and interpretation of video-electroencephalography in adult control rodents. A TASK1-WG1 report of the AES/ILAE Translational Task Force of the ILAE. Epilepsia 2017; 58 Suppl 4:10-27. [PMID: 29105073 DOI: 10.1111/epi.13903] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/21/2017] [Indexed: 01/13/2023]
Abstract
In vivo electrophysiological recordings are widely used in neuroscience research, and video-electroencephalography (vEEG) has become a mainstay of preclinical neuroscience research, including studies of epilepsy and cognition. Studies utilizing vEEG typically involve comparison of measurements obtained from different experimental groups, or from the same experimental group at different times, in which one set of measurements serves as "control" and the others as "test" of the variables of interest. Thus, controls provide mainly a reference measurement for the experimental test. Control rodents represent an undiagnosed population, and cannot be assumed to be "normal" in the sense of being "healthy." Certain physiological EEG patterns seen in humans are also seen in control rodents. However, interpretation of rodent vEEG studies relies on documented differences in frequency, morphology, type, location, behavioral state dependence, reactivity, and functional or structural correlates of specific EEG patterns and features between control and test groups. This paper will focus on the vEEG of standard laboratory rodent strains with the aim of developing a small set of practical guidelines that can assist researchers in the design, reporting, and interpretation of future vEEG studies. To this end, we will: (1) discuss advantages and pitfalls of common vEEG techniques in rodents and propose a set of recommended practices and (2) present EEG patterns and associated behaviors recorded from adult rats of a variety of strains. We will describe the defining features of selected vEEG patterns (brain-generated or artifactual) and note similarities to vEEG patterns seen in adult humans. We will note similarities to normal variants or pathological human EEG patterns and defer their interpretation to a future report focusing on rodent seizure patterns.
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Affiliation(s)
- Shilpa D Kadam
- Department of Neurology, Kennedy Krieger Institute and Johns Hopkins University School of Medicine, Baltimore, Maryland, U.S.A
| | - Raimondo D'Ambrosio
- Department of Neurological Surgery and Regional Epilepsy Center, University of Washington, Seattle, Washington, U.S.A
| | | | | | - Norberto Garcia-Cairasco
- Neurophysiology and Experimental Neuroethology Laboratory, Physiology Department, Ribeirão Preto School of Medicine, University of São Paulo, Ribeirão Preto, Brazil
| | - Akio Ikeda
- Department of Epilepsy, Movement Disorders, and Physiology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Marco de Curtis
- Epileptology and Experimental Neurophysiology Unit, Institutes of Hospitality and Care of a Scientific Nature (IRCCS) Foundation, Carlo Besta Neurological Institute, Milan, Italy
| | - Aristea S Galanopoulou
- Laboratory of Developmental Epilepsy, Saul R. Korey Department of Neurology, Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, U.S.A
| | - Kevin M Kelly
- Brain Injury and Epilepsy Research Laboratory, Allegheny Health Network Research Institute, Allegheny General Hospital, Pittsburgh, Pennsylvania, U.S.A
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13
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Reid AY, Bragin A, Giza CC, Staba RJ, Engel J. The progression of electrophysiologic abnormalities during epileptogenesis after experimental traumatic brain injury. Epilepsia 2016; 57:1558-1567. [PMID: 27495360 PMCID: PMC5207033 DOI: 10.1111/epi.13486] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2016] [Indexed: 12/01/2022]
Abstract
OBJECTIVE Posttraumatic epilepsy (PTE) accounts for 20% of acquired epilepsies. Experimental models are important for studying epileptogenesis. We previously reported that repetitive high-frequency oscillations with spikes (rHFOSs) occur early after lateral fluid percussion injury (FPI) and may be a biomarker for PTE. The objective of this study was to use multiple electrodes in rat hippocampal and neocortical regions to describe the long-term electroencephalographic and behavioral evolution of rHFOSs and epileptic seizures after traumatic brain injury (TBI). METHODS Adult male rats underwent mild, moderate, or severe FPI or sham injury followed by video-electroencephalography (EEG) recordings with a combination of 16 neocortical and hippocampal electrodes at an early, intermediate, or late time-point after injury, up to 52 weeks. Recordings were analyzed for the presence of rHFOSs and seizures. RESULTS Analysis was done on 28 rats with FPI and 7 shams. Perilesional rHFOSs were recorded in significantly more rats after severe (70.3%) than mild (20%) injury or shams (14.3%). Frequency of occurrence was significantly highest in the early (10.8/h) versus late group (3.2/h). Late focal seizures originating from the same electrodes were recorded in significantly more rats in the late (87.5%) versus early period (22.2%), occurring almost exclusively in injured rats. Seizure duration increased significantly over time, averaging 19 s at the beginning of the early period and 27 s at the end of the late period. Seizure frequency also increased significantly over time, from 4.4 per week in the early group to 26.4 per week in the late group. Rarely, rats displayed early seizures or generalized seizures. SIGNIFICANCE FPI results in early rHFOSs and later spontaneous focal seizures arising from peri-lesional neocortex, supporting its use as a model for PTE. Epilepsy severity increased over time and was related to injury severity. The association between early rHFOSs and later focal seizures suggests that rHFOSs may be a potential noninvasive biomarker of PTE.
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Affiliation(s)
- Aylin Y Reid
- Department of Neurology, University of California Los Angeles, Los Angeles, California, U.S.A..
| | - Anatol Bragin
- Department of Neurology, University of California Los Angeles, Los Angeles, California, U.S.A
| | - Christopher C Giza
- Department of Neurosurgery and Pediatric Neurology, University of California Los Angeles, Los Angeles, California, U.S.A
- Brain Research Institute, University of California Los Angeles, Los Angeles, California, U.S.A
- Mattel Children's Hospital - UCLA, University of California Los Angeles, Los Angeles, California, U.S.A
| | - Richard J Staba
- Department of Neurology, University of California Los Angeles, Los Angeles, California, U.S.A
| | - Jerome Engel
- Department of Neurology, University of California Los Angeles, Los Angeles, California, U.S.A
- Brain Research Institute, University of California Los Angeles, Los Angeles, California, U.S.A
- Department of Neurobiology, University of California Los Angeles, Los Angeles, California, U.S.A
- Department of Psychiatry and Biobehavioral Sciences, University of California Los Angeles, Los Angeles, California, U.S.A
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14
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Fit for purpose application of currently existing animal models in the discovery of novel epilepsy therapies. Epilepsy Res 2016; 126:157-84. [PMID: 27505294 DOI: 10.1016/j.eplepsyres.2016.05.016] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 03/06/2016] [Accepted: 05/30/2016] [Indexed: 01/10/2023]
Abstract
Animal seizure and epilepsy models continue to play an important role in the early discovery of new therapies for the symptomatic treatment of epilepsy. Since 1937, with the discovery of phenytoin, almost all anti-seizure drugs (ASDs) have been identified by their effects in animal models, and millions of patients world-wide have benefited from the successful translation of animal data into the clinic. However, several unmet clinical needs remain, including resistance to ASDs in about 30% of patients with epilepsy, adverse effects of ASDs that can reduce quality of life, and the lack of treatments that can prevent development of epilepsy in patients at risk following brain injury. The aim of this review is to critically discuss the translational value of currently used animal models of seizures and epilepsy, particularly what animal models can tell us about epilepsy therapies in patients and which limitations exist. Principles of translational medicine will be used for this discussion. An essential requirement for translational medicine to improve success in drug development is the availability of animal models with high predictive validity for a therapeutic drug response. For this requirement, the model, by definition, does not need to be a perfect replication of the clinical condition, but it is important that the validation provided for a given model is fit for purpose. The present review should guide researchers in both academia and industry what can and cannot be expected from animal models in preclinical development of epilepsy therapies, which models are best suited for which purpose, and for which aspects suitable models are as yet not available. Overall further development is needed to improve and validate animal models for the diverse areas in epilepsy research where suitable fit for purpose models are urgently needed in the search for more effective treatments.
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15
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Dlugos D, Worrell G, Davis K, Stacey W, Szaflarski J, Kanner A, Sunderam S, Rogawski M, Jackson-Ayotunde P, Loddenkemper T, Diehl B, Fureman B, Dingledine R. 2014 Epilepsy Benchmarks Area III: Improve Treatment Options for Controlling Seizures and Epilepsy-Related Conditions Without Side Effects. Epilepsy Curr 2016; 16:192-7. [PMID: 27330452 PMCID: PMC4913858 DOI: 10.5698/1535-7511-16.3.192] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Affiliation(s)
- Dennis Dlugos
- Professor of Neurology and Pediatrics, The Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | - Greg Worrell
- Associate Professor of Neurology, Mayo Systems Electrophysiology Laboratory, Departments of Neurology and Biomedical Engineering, Mayo Clinic, Rochester, MN
| | - Kathryn Davis
- Assistant Professor, Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | - William Stacey
- Assistant Professor of Neurology, Department of Neurology, Department of Biomedical Engineering, University of Michigan
| | - Jerzy Szaflarski
- Professor, Department of Neurology, University of Alabama at Birmingham Department of Neurology and UAB Epilepsy Center, Birmingham, AL
| | - Andres Kanner
- Profressor of Clinical Neurology, Department of Neurology, University of Miami, Miller School of Medicine, Miami, FL
| | - Sridhar Sunderam
- Assistant Professor, Department of Biomedical Engineering, University of Kentucky, Lexington, KY
| | - Mike Rogawski
- Professor, Center for Neurotherapeutics Discovery and Development and Department of Neurology, UC Davis School of Medicine, Sacramento, CA
| | - Patrice Jackson-Ayotunde
- Associate Professor, Department of Pharmaceutical Sciences, University of Maryland Eastern Shore, Princess Anne, MD
| | - Tobias Loddenkemper
- Associate Professor, Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital & Harvard Medical School, Boston, MA
| | - Beate Diehl
- Clinical Neurophysiologist and Neurologist, Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London, London, UK
| | - Brandy Fureman
- Program Director, Channels Synapses and Circuits Cluster, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - Ray Dingledine
- Professor and Chair, Department of Pharmacology, Emory University, Atlanta, GA
| | - for the Epilepsy Benchmark Stewards
- Professor of Neurology and Pediatrics, The Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
- Associate Professor of Neurology, Mayo Systems Electrophysiology Laboratory, Departments of Neurology and Biomedical Engineering, Mayo Clinic, Rochester, MN
- Assistant Professor, Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
- Assistant Professor of Neurology, Department of Neurology, Department of Biomedical Engineering, University of Michigan
- Professor, Department of Neurology, University of Alabama at Birmingham Department of Neurology and UAB Epilepsy Center, Birmingham, AL
- Profressor of Clinical Neurology, Department of Neurology, University of Miami, Miller School of Medicine, Miami, FL
- Assistant Professor, Department of Biomedical Engineering, University of Kentucky, Lexington, KY
- Professor, Center for Neurotherapeutics Discovery and Development and Department of Neurology, UC Davis School of Medicine, Sacramento, CA
- Associate Professor, Department of Pharmaceutical Sciences, University of Maryland Eastern Shore, Princess Anne, MD
- Associate Professor, Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital & Harvard Medical School, Boston, MA
- Clinical Neurophysiologist and Neurologist, Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London, London, UK
- Program Director, Channels Synapses and Circuits Cluster, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
- Professor and Chair, Department of Pharmacology, Emory University, Atlanta, GA
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16
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Rodgers KM, Dudek FE, Barth DS. Progressive, Seizure-Like, Spike-Wave Discharges Are Common in Both Injured and Uninjured Sprague-Dawley Rats: Implications for the Fluid Percussion Injury Model of Post-Traumatic Epilepsy. J Neurosci 2015; 35:9194-204. [PMID: 26085641 PMCID: PMC6605152 DOI: 10.1523/jneurosci.0919-15.2015] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 04/19/2015] [Accepted: 05/10/2015] [Indexed: 01/05/2023] Open
Abstract
Variable-duration oscillations and repetitive, high-voltage spikes have been recorded in the electrocorticogram (ECoG) of rats weeks and months after fluid percussion injury (FPI), a model of traumatic brain injury. These ECoG events, which have many similarities to spike-wave-discharges (SWDs) and absence seizures, have been proposed to represent nonconvulsive seizures characteristic of post-traumatic epilepsy (PTE). The present study quantified features of SWD episodes in rats at different time points after moderate to severe FPI, and compared them with age-matched control rats. Control and FPI-injured rats at 1 year of age displayed large-amplitude and frequent SWD events at frontal and parietal recording sites. At 3-6 months, SWDs were shorter in duration and less frequent; extremely brief SWDs (i.e., "larval") were detected as early as 1 month. The onset of the SWDs was nearly always synchronous across electrodes and of larger amplitude in frontal regions. A sensory stimulus, such as a click, immediately and consistently stopped the occurrence of the SWDs. SWDs were consistently accompanied by behavioral arrest. All features of SWDs in control and experimental (FPI) rats were indistinguishable. None of the FPI-treated rats developed nonconvulsive or convulsive seizures that could be distinguished electrographically or behaviorally from SWDs. Because SWDs have features similar to genetic absence seizures, these results challenge the hypothesis that SWDs after FPI reflect PTE.
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Affiliation(s)
- Krista M Rodgers
- Department of Psychology and Neuroscience, University of Colorado, Boulder, Colorado 80309, and
| | - F Edward Dudek
- Department of Neurosurgery, University of Utah School of Medicine, Salt Lake City, Utah 84108
| | - Daniel S Barth
- Department of Psychology and Neuroscience, University of Colorado, Boulder, Colorado 80309, and
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