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Löscher W. Mammalian models of status epilepticus - Their value and limitations. Epilepsy Behav 2024; 158:109923. [PMID: 38944026 DOI: 10.1016/j.yebeh.2024.109923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2024] [Revised: 06/23/2024] [Accepted: 06/24/2024] [Indexed: 07/01/2024]
Abstract
Status epilepticus (SE) is a medical and neurologic emergency that may lead to permanent brain damage, morbidity, or death. Animal models of SE are particularly important to study the pathophysiology of SE and mechanisms of SE resistance to antiseizure medications with the aim to develop new, more effective treatments. In addition to rodents (rats or mice), larger mammalian species such as dogs, pigs, and nonhuman primates are used. This short review describes and discusses the value and limitations of the most frequently used mammalian models of SE. Issues that are discussed include (1) differences between chemical and electrical SE models; (2) the role of genetic background and environment on SE in rodents; (3) the use of rodent models (a) to study the pathophysiology of SE and mechanisms of SE resistance; (b) to study developmental aspects of SE; (c) to study the efficacy of new treatments, including drug combinations, for refractory SE; (d) to study the long-term consequences of SE and identify biomarkers; (e) to develop treatments that prevent or modify epilepsy; (e) to study the pharmacology of spontaneous seizures; (4) the limitations of animal models of induced SE; and (5) the advantages (and limitations) of naturally (spontaneously) occurring SE in epileptic dogs and nonhuman primates. Overall, mammalian models of SE have significantly increased our understanding of the pathophysiology and drug resistance of SE and identified potential targets for new, more effective treatments. This paper was presented at the 9th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures held in April 2024.
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Affiliation(s)
- Wolfgang Löscher
- Translational Neuropharmacology Lab, NIFE, Department of Experimental Otology of the ENT Clinics, Hannover Medical School, Hannover, Germany.
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Acedo Reina E, Germany Morrison E, Dereli AS, Collard E, Raffoul R, Nonclercq A, El Tahry R. Vagus nerve electroneurogram-based detection of acute kainic acid induced seizures. Front Neurosci 2024; 18:1427308. [PMID: 39170680 PMCID: PMC11335647 DOI: 10.3389/fnins.2024.1427308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2024] [Accepted: 07/02/2024] [Indexed: 08/23/2024] Open
Abstract
Seizures produce autonomic symptoms, mainly sympathetic but also parasympathetic in origin. Within this context, the vagus nerve is a key player as it carries information from the different organs to the brain and vice versa. Hence, exploiting vagal neural traffic for seizure detection might be a promising tool to improve the efficacy of closed-loop Vagus Nerve Stimulation. This study developed a VENG detection algorithm that effectively detects seizures by emphasizing the loss of spontaneous rhythmicity associated with respiration in acute intrahippocampal Kainic Acid rat model. Among 20 induced seizures in six anesthetized rats, 13 were detected (sensitivity: 65%, accuracy: 92.86%), with a mean VENG-detection delay of 25.3 ± 13.5 s after EEG-based seizure onset. Despite variations in detection parameters, 7 out of 20 seizures exhibited no ictal VENG modifications and remained undetected. Statistical analysis highlighted a significant difference in Delta, Theta and Beta band evolution between detected and undetected seizures, in addition to variations in the magnitude of HR changes. Binomial logistic regression analysis confirmed that an increase in delta and theta band activity was associated with a decreased likelihood of seizure detection. This results suggest the possibility of distinct seizure spreading patterns between the two groups which may results in differential activation of the autonomic central network. Despite notable progress, limitations, particularly the absence of respiration recording, underscore areas for future exploration and refinement in closed-loop stimulation strategies for epilepsy management. This study constitutes the initial phase of a longitudinal investigation, which will subsequently involve reproducing these experiments in awake conditions with spontaneous recurrent seizures.
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Affiliation(s)
- Elena Acedo Reina
- Clinical Neuroscience, Institute of Neuroscience (IoNS), Université Catholique de Louvain, Brussels, Belgium
| | - Enrique Germany Morrison
- Clinical Neuroscience, Institute of Neuroscience (IoNS), Université Catholique de Louvain, Brussels, Belgium
- Walloon Excellence in Life Sciences and Biotechnology (WELBIO) Department, WEL Research Institute, Wavre, Belgium
| | - Ayse S. Dereli
- Clinical Neuroscience, Institute of Neuroscience (IoNS), Université Catholique de Louvain, Brussels, Belgium
| | - Elise Collard
- Clinical Neuroscience, Institute of Neuroscience (IoNS), Université Catholique de Louvain, Brussels, Belgium
| | - Romain Raffoul
- BEAMS Department, Université Libre de Bruxelles, Brussels, Belgium
| | | | - Riëm El Tahry
- Clinical Neuroscience, Institute of Neuroscience (IoNS), Université Catholique de Louvain, Brussels, Belgium
- Walloon Excellence in Life Sciences and Biotechnology (WELBIO) Department, WEL Research Institute, Wavre, Belgium
- Department of Neurology, Center for Refractory Epilepsy, Cliniques Universitaires Saint-Luc, Brussels, Belgium
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Kimmons LA, Alzayadneh M, Metter EJ, Alsherbini K. Safety and Efficacy of Ketamine Without Intubation in the Management of Refractory Seizures: A Case Series. Neurocrit Care 2024; 40:689-697. [PMID: 37610640 DOI: 10.1007/s12028-023-01811-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 07/11/2023] [Indexed: 08/24/2023]
Abstract
BACKGROUND Continuous infusion ketamine has demonstrated efficacy in the management of refractory seizures yet does not suppress respiratory drive like other continuous infusion anesthetics (CIAs) used for this indication. The aim of this study is to describe the safety and efficacy of ketamine infusions in patients with refractory seizure without intubation. METHODS We analyzed a retrospective cohort of adult patients who were not intubated at the time of initiation of a ketamine infusion for refractory seizures. Seizure onset was determined to be the first clinical seizure or nonconvulsive seizure reported on electroencephalography (EEG) or the start time of EEG for patients with seizures at EEG initiation. Responders were defined as patients with resolution of seizures within 24 h of initiation without the need for intubation or an additional CIA. RESULTS A total of 28 patients were analyzed (median age 62 years, 64.3% female, 82.1% African American, 82.1% with structural seizure etiology, and 85.7% focal seizures). Of patients, 78.5% received an initial bolus averaging 0.9 mg/kg, and the majority (89.3%) were initiated on an infusion at 10 μg/kg/minute; median duration was 39.8 h. Maximum infusion rates were 10 μg/kg/minute in 16 patients, 20 μg/kg/minute in seven patients, and 30 μg/kg/minute in five patients. Of patients, 71.4% were assessed to be ketamine responders; six of the eight nonresponders required intubation and an additional CIA. Responders were 80% more likely to have received ketamine 5 or more hours earlier than nonresponders. Hypotension (systolic blood pressure < 90 mmHg) occurred in 31.8% of patients receiving only ketamine, which did not correlate with duration or maximum dose of ketamine; hypertension (systolic blood pressure > 180 mmHg) occurred in 39.3%. CONCLUSIONS Ketamine represents a safe and effective treatment option for refractory seizures and has potential to reduce morbidity associated with intubation in a carefully selected patient population. Early initiation may increase the likelihood of success.
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Affiliation(s)
- Lauren A Kimmons
- Methodist University Hospital, 1265 Union Avenue, Memphis, TN, 38104, USA.
- University of Tennessee Health Sciences Center, 910 Madison Avenue, Memphis, TN, 38163, USA.
| | - Mohammad Alzayadneh
- University of Tennessee Health Sciences Center, 910 Madison Avenue, Memphis, TN, 38163, USA
| | - E Jeffrey Metter
- University of Tennessee Health Sciences Center, 910 Madison Avenue, Memphis, TN, 38163, USA
| | - Khalid Alsherbini
- Methodist University Hospital, 1265 Union Avenue, Memphis, TN, 38104, USA
- University of Tennessee Health Sciences Center, 910 Madison Avenue, Memphis, TN, 38163, USA
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Nguyen DA, Stone MF, Schultz CR, de Araujo Furtado M, Niquet J, Wasterlain CG, Lumley LA. Evaluation of Midazolam-Ketamine-Allopregnanolone Combination Therapy against Cholinergic-Induced Status Epilepticus in Rats. J Pharmacol Exp Ther 2024; 388:376-385. [PMID: 37770198 PMCID: PMC10801769 DOI: 10.1124/jpet.123.001784] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 09/01/2023] [Accepted: 09/06/2023] [Indexed: 10/03/2023] Open
Abstract
Status epilepticus (SE) is a life-threatening development of self-sustaining seizures that becomes resistant to benzodiazepines when treatment is delayed. Benzodiazepine pharmacoresistance is thought in part to result from internalization of synaptic GABAA receptors, which are the main target of the drug. The naturally occurring neurosteroid allopregnanolone is a therapy of interest against SE for its ability to modulate all isoforms of GABAA receptors. Ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, has been partially effective in combination with benzodiazepines in mitigating SE-associated neurotoxicity. In this study, allopregnanolone as an adjunct to midazolam or midazolam-ketamine combination therapy was evaluated for efficacy against cholinergic-induced SE. Adult male rats implanted with electroencephalographic (EEG) telemetry devices were exposed to the organophosphorus chemical (OP) soman (GD) and treated with an admix of atropine sulfate and HI-6 at 1 minute after exposure followed by midazolam, midazolam-allopregnanolone, or midazolam-ketamine-allopregnanolone 40 minutes after seizure onset. Neurodegeneration, neuronal loss, and neuroinflammation were assessed 2 weeks after GD exposure. Seizure activity, EEG power integral, and epileptogenesis were also compared among groups. Overall, midazolam-ketamine-allopregnanolone combination therapy was effective in reducing cholinergic-induced toxic signs and neuropathology, particularly in the thalamus and hippocampus. Higher dosage of allopregnanolone administered in combination with midazolam and ketamine was also effective in reducing EEG power integral and epileptogenesis. The current study reports that there is a promising potential of neurosteroids in combination with benzodiazepine and ketamine treatments in a GD model of SE. SIGNIFICANCE STATEMENT: Allopregnanolone, a naturally occurring neurosteroid, reduced pathologies associated with soman (GD) exposure such as epileptogenesis, neurodegeneration, and neuroinflammation, and suppressed GD-induced toxic signs when used as an adjunct to midazolam and ketamine in a delayed treatment model of soman-induced status epilepticus (SE) in rats. However, protection was incomplete, suggesting that further studies are needed to identify optimal combinations of antiseizure medications and routes of administration for maximal efficacy against cholinergic-induced SE.
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Affiliation(s)
- Donna A Nguyen
- Neuroscience Department, US Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, Maryland (D.A.N., M.F.S., C.R.S., L.A.L.); BioSEaD, LLC, Rockville, Maryland (M.D.A.F.); Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California (J.N., C.G.W.); and Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California (J.N., C.G.W.)
| | - Michael F Stone
- Neuroscience Department, US Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, Maryland (D.A.N., M.F.S., C.R.S., L.A.L.); BioSEaD, LLC, Rockville, Maryland (M.D.A.F.); Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California (J.N., C.G.W.); and Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California (J.N., C.G.W.)
| | - Caroline R Schultz
- Neuroscience Department, US Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, Maryland (D.A.N., M.F.S., C.R.S., L.A.L.); BioSEaD, LLC, Rockville, Maryland (M.D.A.F.); Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California (J.N., C.G.W.); and Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California (J.N., C.G.W.)
| | - Marcio de Araujo Furtado
- Neuroscience Department, US Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, Maryland (D.A.N., M.F.S., C.R.S., L.A.L.); BioSEaD, LLC, Rockville, Maryland (M.D.A.F.); Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California (J.N., C.G.W.); and Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California (J.N., C.G.W.)
| | - Jerome Niquet
- Neuroscience Department, US Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, Maryland (D.A.N., M.F.S., C.R.S., L.A.L.); BioSEaD, LLC, Rockville, Maryland (M.D.A.F.); Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California (J.N., C.G.W.); and Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California (J.N., C.G.W.)
| | - Claude G Wasterlain
- Neuroscience Department, US Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, Maryland (D.A.N., M.F.S., C.R.S., L.A.L.); BioSEaD, LLC, Rockville, Maryland (M.D.A.F.); Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California (J.N., C.G.W.); and Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California (J.N., C.G.W.)
| | - Lucille A Lumley
- Neuroscience Department, US Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, Maryland (D.A.N., M.F.S., C.R.S., L.A.L.); BioSEaD, LLC, Rockville, Maryland (M.D.A.F.); Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California (J.N., C.G.W.); and Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California (J.N., C.G.W.)
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Perlmutter M, Price M, Kothari K, Rafique Z, Rogers Keene K, De La Rosa X, Weinstein E, Patrick C. Prehospital Treatment of Benzodiazepine-Resistant Pediatric Status Epilepticus with Parenteral Ketamine: A Case Series. PREHOSP EMERG CARE 2023; 27:920-926. [PMID: 37276174 DOI: 10.1080/10903127.2023.2221967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 05/26/2023] [Accepted: 05/27/2023] [Indexed: 06/07/2023]
Abstract
We report the initial six pediatric patients treated with ketamine for benzodiazepine-resistant status epilepticus in an urban, ground-based emergency medical services (EMS) system. Evidence for ketamine as a second-line agent for both adult and pediatric refractory seizure activity in the hospital setting has increased over the past decade. The availability of an inexpensive and familiar second-line prehospital anti-epileptic drug option is extremely desirable. We believe these initial data demonstrate promising seizure control effects without significant respiratory depression, indicating a potential role for ketamine in the EMS treatment of pediatric benzodiazepine-refractory seizures.
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Affiliation(s)
- Michael Perlmutter
- Department of Emergency Medicine, Hennepin County Medical Center, Minneapolis, Minnesota
| | - Mark Price
- Harris County ESD11 Mobile Healthcare, Houston, Texas
| | - Kathryn Kothari
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Zubaid Rafique
- Department of Emergency Medicine, Baylor College of Medicine, Houston, Texas
| | - Kelly Rogers Keene
- Department of Emergency Medicine, Baylor College of Medicine, Houston, Texas
| | | | - Elizabeth Weinstein
- Division of Pediatric Emergency Medicine, Department of Emergency Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Casey Patrick
- Harris County ESD11 Mobile Healthcare, Houston, Texas
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Niquet J, Nguyen D, de Araujo Furtado M, Lumley L. Treatment of cholinergic-induced status epilepticus with polytherapy targeting GABA and glutamate receptors. Epilepsia Open 2023; 8 Suppl 1:S117-S140. [PMID: 36807554 PMCID: PMC10173853 DOI: 10.1002/epi4.12713] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 02/15/2023] [Indexed: 02/23/2023] Open
Abstract
Despite new antiseizure medications, the development of cholinergic-induced refractory status epilepticus (RSE) continues to be a therapeutic challenge as pharmacoresistance to benzodiazepines and other antiseizure medications quickly develops. Studies conducted by Epilepsia. 2005;46:142 demonstrated that the initiation and maintenance of cholinergic-induced RSE are associated with trafficking and inactivation of gamma-aminobutyric acid A receptors (GABAA R) thought to contribute to the development of benzodiazepine pharmacoresistance. In addition, Dr. Wasterlain's laboratory reported that increased N-methyl-d-aspartate receptors (NMDAR) and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPAR) contribute to enhanced glutamatergic excitation (Neurobiol Dis. 2013;54:225; Epilepsia. 2013;54:78). Thus, Dr. Wasterlain postulated that targeting both maladaptive responses of reduced inhibition and increased excitation that is associated with cholinergic-induced RSE should improve therapeutic outcome. We currently review studies in several animal models of cholinergic-induced RSE that demonstrate that benzodiazepine monotherapy has reduced efficacy when treatment is delayed and that polytherapy with drugs that include a benzodiazepine (eg midazolam and diazepam) to counter loss of inhibition, concurrent with an NMDA antagonist (eg ketamine) to reduce excitation provide improved efficacy. Improved efficacy with polytherapy against cholinergic-induced seizure is demonstrated by reduction in (1) seizure severity, (2) epileptogenesis, and (3) neurodegeneration compared with monotherapy. Animal models reviewed include pilocarpine-induced seizure in rats, organophosphorus nerve agent (OPNA)-induced seizure in rats, and OPNA-induced seizure in two mouse models: (1) carboxylesterase knockout (Es1-/- ) mice which, similarly to humans, lack plasma carboxylesterase and (2) human acetylcholinesterase knock-in carboxylesterase knockout (KIKO) mice. We also review studies showing that supplementing midazolam and ketamine with a third antiseizure medication (valproate or phenobarbital) that targets a nonbenzodiazepine site rapidly terminates RSE and provides further protection against cholinergic-induced SE. Finally, we review studies on the benefits of simultaneous compared with sequential drug treatments and the clinical implications that lead us to predict improved efficacy of early combination drug therapies. The data generated from seminal rodent studies of efficacious treatment of cholinergic-induced RSE conducted under Dr. Wasterlain's guidance suggest that future clinical trials should treat the inadequate inhibition and temper the excess excitation that characterize RSE and that early combination therapies may provide improved outcome over benzodiazepine monotherapy.
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Affiliation(s)
- Jerome Niquet
- Department of NeurologyDavid Geffen School of Medicine at UCLALos AngelesCaliforniaUSA
- Epilepsy Research LaboratoryVeterans Affairs Greater Los Angeles Healthcare SystemLos AngelesCaliforniaUSA
| | - Donna Nguyen
- Neuroscience DepartmentU.S. Army Medical Research Institute of Chemical Defense (USAMRICD)Aberdeen Proving GroundMarylandUSA
| | | | - Lucille Lumley
- Neuroscience DepartmentU.S. Army Medical Research Institute of Chemical Defense (USAMRICD)Aberdeen Proving GroundMarylandUSA
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Coles L, Rosenthal ES, Bleck TP, Elm J, Zehtabchi S, Chamberlain J, Cloyd J, Shinnar S, Silbergleit R, Kapur J. Why ketamine. Epilepsy Behav 2023; 141:109066. [PMID: 36609129 PMCID: PMC10073319 DOI: 10.1016/j.yebeh.2022.109066] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/19/2022] [Accepted: 12/20/2022] [Indexed: 01/06/2023]
Abstract
We present the rationale for testing ketamine as an add-on therapy for treating benzodiazepine refractory (established) status epilepticus. In animal studies, ketamine terminates benzodiazepine refractory status epilepticus by interfering with the pathophysiological mechanisms and is a neuroprotectant. Ketamine does not suppress respiration when used for sedation and anesthesia. A Series of reports suggest that ketamine can help terminate refractory and super refractory status epilepticus. We propose to use 1 or 3 mg/Kg ketamine intravenously based on animal-to-human conversion and pharmacokinetic studies. This paper was presented at the 8th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures held in September 2022.
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Affiliation(s)
- Lisa Coles
- Center for Orphan Drug Research, Department of Experimental and Clinical Pharmacology, College of Pharmacy, University of Minnesota, Minneapolis, MN, United States
| | - Eric S Rosenthal
- Department of Neurology, Massachusetts General Hospital, Boston, MA, United States
| | - Thomas P Bleck
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Jordan Elm
- Department of Public Health Sciences, Medical University of South Carolina, Charleston, SC, United States
| | - Shahriar Zehtabchi
- Department of Emergency Medicine, Downstate Health Sciences University, Brooklyn, NY, United States
| | - James Chamberlain
- Division of Emergency Medicine, Children's National Hospital Washington, DC, United States
| | - James Cloyd
- Center for Orphan Drug Research, Department of Experimental and Clinical Pharmacology, College of Pharmacy, University of Minnesota, Minneapolis, MN, United States
| | - Shlomo Shinnar
- Departments of Neurology, Pediatrics, Epidemiology and Public Health, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Robert Silbergleit
- Department of Emergency Medicine, University of Michigan, School of Medicine, Ann Arbor, MI, United States
| | - Jaideep Kapur
- Department of Neurology and Neuroscience, University of Virginia, School of Medicine, Charlottesville, VA, United States.
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Naylor DE. In the fast lane: Receptor trafficking during status epilepticus. Epilepsia Open 2023; 8 Suppl 1:S35-S65. [PMID: 36861477 PMCID: PMC10173858 DOI: 10.1002/epi4.12718] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 02/23/2023] [Indexed: 03/03/2023] Open
Abstract
Status epilepticus (SE) remains a significant cause of morbidity and mortality and often is refractory to standard first-line treatments. A rapid loss of synaptic inhibition and development of pharmacoresistance to benzodiazepines (BZDs) occurs early during SE, while NMDA and AMPA receptor antagonists remain effective treatments after BZDs have failed. Multimodal and subunit-selective receptor trafficking within minutes to an hour of SE involves GABA-A, NMDA, and AMPA receptors and contributes to shifts in the number and subunit composition of surface receptors with differential impacts on the physiology, pharmacology, and strength of GABAergic and glutamatergic currents at synaptic and extrasynaptic sites. During the first hour of SE, synaptic GABA-A receptors containing γ2 subunits move to the cell interior while extrasynaptic GABA-A receptors with δ subunits are preserved. Conversely, NMDA receptors containing N2B subunits are increased at synaptic and extrasynaptic sites, and homomeric GluA1 ("GluA2-lacking") calcium permeant AMPA receptor surface expression also is increased. Molecular mechanisms, largely driven by NMDA receptor or calcium permeant AMPA receptor activation early during circuit hyperactivity, regulate subunit-specific interactions with proteins involved with synaptic scaffolding, adaptin-AP2/clathrin-dependent endocytosis, endoplasmic reticulum (ER) retention, and endosomal recycling. Reviewed here is how SE-induced shifts in receptor subunit composition and surface representation increase the excitatory to inhibitory imbalance that sustains seizures and fuels excitotoxicity contributing to chronic sequela such as "spontaneous recurrent seizures" (SRS). A role for early multimodal therapy is suggested both for treatment of SE and for prevention of long-term comorbidities.
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Affiliation(s)
- David E Naylor
- VA Greater Los Angeles Healthcare System, Department of Neurology, David Geffen School of Medicine at UCLA, and The Lundquist Institute at Harbor-UCLA Medical Center, Los Angeles, California, USA
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Insight into Drug Resistance in Status Epilepticus: Evidence from Animal Models. Int J Mol Sci 2023; 24:ijms24032039. [PMID: 36768361 PMCID: PMC9917109 DOI: 10.3390/ijms24032039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 01/11/2023] [Accepted: 01/15/2023] [Indexed: 01/22/2023] Open
Abstract
Status epilepticus (SE), a condition with abnormally prolonged seizures, is a severe type of epilepsy. At present, SE is not well controlled by clinical treatments. Antiepileptic drugs (AEDs) are the main therapeutic approaches, but they are effective for SE only with a narrow intervening window, and they easily induce resistance. Thus, in this review, we provide an updated summary for an insight into drug-resistant SE, hoping to add to the understanding of the mechanism of refractory SE and the development of active compounds. Firstly, we briefly outline the limitations of current drug treatments for SE by summarizing the extensive experimental literature and clinical data through a search of the PubMed database, and then summarize the common animal models of refractory SE with their advantages and disadvantages. Notably, we also briefly review some of the hypotheses about drug resistance in SE that are well accepted in the field, and furthermore, put forward future perspectives for follow-up research on SE.
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Cagnotti G, Ferrini S, Muro GD, Borriello G, Corona C, Manassero L, Avilii E, Bellino C, D'Angelo A. Constant rate infusion of diazepam or propofol for the management of canine cluster seizures or status epilepticus. Front Vet Sci 2022; 9:1005948. [PMID: 36467660 PMCID: PMC9713018 DOI: 10.3389/fvets.2022.1005948] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 11/04/2022] [Indexed: 11/04/2023] Open
Abstract
INTRODUCTION Cluster seizures (CS) and status epilepticus (SE) in dogs are severe neurological emergencies that require immediate treatment. Practical guidelines call for constant rate infusion (CRI) of benzodiazepines or propofol (PPF) in patients with seizures not responding to first-line treatment, but to date only few studies have investigated the use of CRI in dogs with epilepsy. STUDY DESIGN Retrospective clinical study. METHODS Dogs that received CRI of diazepam (DZP) or PPF for antiepileptic treatment during hospitalization at the Veterinary Teaching Hospital of the University of Turin for CS or SE between September 2016 and December 2019 were eligible for inclusion. Favorable outcome was defined as cessation of clinically visible seizure activity within few minutes from the initiation of the CRI, no seizure recurrence within 24 h after discontinuation of CRI through to hospital discharge, and clinical recovery. Poor outcome was defined as recurrence of seizure activity despite treatment or death in hospital because of recurrent seizures, catastrophic consequences of prolonged seizures or no return to an acceptable neurological and clinical baseline, despite apparent control of seizure activity. Comparisons between the number of patients with favorable outcome and those with poor outcome in relation to type of CRI, seizure etiology, reason for presentation (CS or SE), sex, previous AED therapy and dose of PPF CRI were carried out. RESULTS A total of 37 dogs, with 50 instances of hospitalization and CRI administered for CS or SE were included in the study. CRI of diazepam (DZP) or PPF was administered in 29/50 (58%) and in 21/50 (42%) instances of hospitalization, respectively. Idiopathic epilepsy was diagnosed in 21/37 (57%), (13/21 tier I and 8/21 tier II); structural epilepsy was diagnosed in 6/37 (16%) of which 4/6 confirmed and 2/6 suspected. A metabolic or toxic cause of seizure activity was recorded in 7/37 (19%). A total of 38/50 (76%) hospitalizations were noted for CS and 12/50 (24%) for SE. In 30/50 (60%) instances of hospitalization, the patient responded well to CRI with cessation of seizure activity, no recurrence in the 24 h after discontinuation of CRI through to hospital discharge, whereas a poor outcome was recorded for 20/50 (40%) cases (DZP CRI in 12/50 and PPF CRI in 8/50). Comparison between the number of patients with favorable outcome and those with poor outcome in relation to type of CRI, seizure etiology, reason for presentation (CS or SE), sex and previous AED therapy was carried out but no statistically significant differences were found. CONCLUSIONS The present study is the first to document administration of CRI of DZP or PPF in a large sample of dogs with epilepsy. The medications appeared to be tolerated without major side effects and helped control seizure activity in most patients regardless of seizure etiology. Further studies are needed to evaluate the effects of CRI duration on outcome and complications.
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Affiliation(s)
- Giulia Cagnotti
- Department of Veterinary Science, University of Turin, Torino, Italy
| | - Sara Ferrini
- Department of Veterinary Science, University of Turin, Torino, Italy
| | - Giorgia Di Muro
- Department of Veterinary Science, University of Turin, Torino, Italy
| | | | - Cristiano Corona
- Istituto Zooprofilattico del Piemonte, Liguria e Valle d'Aosta, Torino, Italy
| | - Luca Manassero
- Department of Veterinary Science, University of Turin, Torino, Italy
| | - Eleonora Avilii
- Department of Veterinary Science, University of Turin, Torino, Italy
| | - Claudio Bellino
- Department of Veterinary Science, University of Turin, Torino, Italy
| | - Antonio D'Angelo
- Department of Veterinary Science, University of Turin, Torino, Italy
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11
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Sivakumar S, Ghasemi M, Schachter SC. Targeting NMDA Receptor Complex in Management of Epilepsy. Pharmaceuticals (Basel) 2022; 15:ph15101297. [PMID: 36297409 PMCID: PMC9609646 DOI: 10.3390/ph15101297] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 10/17/2022] [Accepted: 10/20/2022] [Indexed: 11/05/2022] Open
Abstract
N-methyl-D-aspartate receptors (NMDARs) are widely distributed in the central nervous system (CNS) and play critical roles in neuronal excitability in the CNS. Both clinical and preclinical studies have revealed that the abnormal expression or function of these receptors can underlie the pathophysiology of seizure disorders and epilepsy. Accordingly, NMDAR modulators have been shown to exert anticonvulsive effects in various preclinical models of seizures, as well as in patients with epilepsy. In this review, we provide an update on the pathologic role of NMDARs in epilepsy and an overview of the NMDAR antagonists that have been evaluated as anticonvulsive agents in clinical studies, as well as in preclinical seizure models.
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Affiliation(s)
- Shravan Sivakumar
- Department of Neurology, University of Massachusetts Chan Medical School, Worcester, MA 01655, USA
| | - Mehdi Ghasemi
- Department of Neurology, University of Massachusetts Chan Medical School, Worcester, MA 01655, USA
- Correspondence: (M.G.); (S.C.S.)
| | - Steven C. Schachter
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
- Harvard Medical School, Boston, MA 02114, USA
- Consortia for Improving Medicine with Innovation & Technology (CIMIT), Boston, MA 02114, USA
- Correspondence: (M.G.); (S.C.S.)
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12
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Zhou R, Wang Y, Cao X, Li Z, Yu J. Diazepam Monotherapy or Diazepam-Ketamine Dual Therapy at Different Time Points Terminates Seizures and Reduces Mortality in a Status Epilepticus Animal Model. Med Sci Monit 2021; 27:e934043. [PMID: 34866132 PMCID: PMC8662960 DOI: 10.12659/msm.934043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 11/08/2021] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Being refractory to drugs remains an urgent treatment problem in status epilepticus (SE). The fact that γ-aminobutyric acid A receptors (GABAARs) become internalized and inactive, N-methyl-D-aspartate receptors (NMDARs) become externalized and active during SE may explain the refractoriness to benzodiazepine. However, the real-time dynamic efficacy of antiepileptic drugs remains unclear. Therefore, we propose a hypothesis that diazepam monotherapy or diazepam-ketamine dual therapy could terminate seizures and reduce mortality in the SE model at different time points during ongoing SE. MATERIAL AND METHODS An SE model was established in adult Sprague-Dawley rats with lithium and pilocarpine. The GABAAR agonist diazepam was injected at 5, 10, 20, or 30 min when SE continued. In addition, diazepam and the NMDAR antagonist ketamine were injected at 10 to 60 min at 6 different time points. We measured seizure-free rates, seizure duration, degree of behavioral seizure, and mortality. RESULTS Diazepam monotherapy at 5 min and 10 min from the beginning of SE was able to terminate seizures and improved survival rates. Diazepam-ketamine dual therapy at 10 min, 20 min, and 30 min from the beginning of SE terminated seizures and achieved high survival rates. CONCLUSIONS In this parallel randomized controlled trial with a rat model, we found that diazepam monotherapy was an effective antiepileptic strategy at the early stage of SE less than 10 min after SE onset. If SE lasts more than 10 min but less than 30 min, the diazepam-ketamine dual therapy strategy may be an appropriate choice.
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Affiliation(s)
- Ruijiao Zhou
- Department of Neurology, The Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan, PR China
| | - Yanlin Wang
- Department of Clinical Medicine, North Sichuan Medical College, Nanchong, Sichuan, PR China
| | - Xing Cao
- Department of Neurology, The Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan, PR China
| | - Zhimin Li
- Department of Neurology, The Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan, PR China
| | - Juming Yu
- Department of Neurology, The Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan, PR China
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13
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Lumley LA, Marrero-Rosado B, Rossetti F, Schultz CR, Stone MF, Niquet J, Wasterlain CG. Combination of antiseizure medications phenobarbital, ketamine, and midazolam reduces soman-induced epileptogenesis and brain pathology in rats. Epilepsia Open 2021; 6:757-769. [PMID: 34657398 PMCID: PMC8633481 DOI: 10.1002/epi4.12552] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 10/07/2021] [Accepted: 10/12/2021] [Indexed: 12/16/2022] Open
Abstract
Objective Cholinergic‐induced status epilepticus (SE) is associated with a loss of synaptic gamma‐aminobutyric acid A receptors (GABAAR) and an increase in N‐methyl‐D‐aspartate receptors (NMDAR) and amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid receptors (AMPAR) that may contribute to pharmacoresistance when treatment with benzodiazepine antiseizure medication is delayed. The barbiturate phenobarbital enhances inhibitory neurotransmission by binding to a specific site in the GABAAR to increase the open state of the channel, decrease neuronal excitability, and reduce glutamate‐induced currents through AMPA/kainate receptors. We hypothesized that phenobarbital as an adjunct to midazolam would augment the amelioration of soman‐induced SE and associated neuropathological changes and that further protection would be provided by the addition of an NMDAR antagonist. Methods We investigated the efficacy of combining antiseizure medications to include a benzodiazepine and a barbiturate allosteric GABAAR modulator (midazolam and phenobarbital, respectively) to correct loss of inhibition, and ketamine to reduce excitation caused by increased synaptic localization of NMDAR and AMPAR, which are NMDA‐dependent. Rats implanted with transmitters to record electroencephalographic (EEG) activity were exposed to soman and treated with atropine sulfate and HI‐6 one min after exposure and with antiseizure medication(s) 40 minutes after seizure onset. Results The triple therapy combination of phenobarbital, midazolam, and ketamine administered at 40 minutes after seizure onset effectively prevented soman‐induced epileptogenesis and reduced neurodegeneration. In addition, dual therapy with phenobarbital and midazolam or ketamine was more effective than monotherapy (midazolam or phenobarbital) in reducing cholinergic‐induced toxicity. Significance Benzodiazepine efficacy is drastically reduced with time after seizure onset and inversely related to seizure duration. To overcome pharmacoresistance in severe benzodiazepine‐refractory cholinergic‐induced SE, simultaneous drug combination to include drugs that target both the loss of inhibition (eg, midazolam, phenobarbital) and the increased excitatory response (eg, ketamine) is more effective than benzodiazepine or barbiturate monotherapy.
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Affiliation(s)
- Lucille A Lumley
- Neuroscience Department, U.S. Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, Maryland, USA
| | - Brenda Marrero-Rosado
- Neuroscience Department, U.S. Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, Maryland, USA
| | - Franco Rossetti
- Military Psychiatry and Neuroscience Department, Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
| | - Caroline R Schultz
- Neuroscience Department, U.S. Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, Maryland, USA
| | - Michael F Stone
- Neuroscience Department, U.S. Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, Maryland, USA
| | - Jerome Niquet
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.,Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, USA
| | - Claude G Wasterlain
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.,Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, USA
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14
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Lévesque M, Biagini G, de Curtis M, Gnatkovsky V, Pitsch J, Wang S, Avoli M. The pilocarpine model of mesial temporal lobe epilepsy: Over one decade later, with more rodent species and new investigative approaches. Neurosci Biobehav Rev 2021; 130:274-291. [PMID: 34437936 DOI: 10.1016/j.neubiorev.2021.08.020] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 08/17/2021] [Accepted: 08/21/2021] [Indexed: 01/19/2023]
Abstract
Fundamental work on the mechanisms leading to focal epileptic discharges in mesial temporal lobe epilepsy (MTLE) often rests on the use of rodent models in which an initial status epilepticus (SE) is induced by kainic acid or pilocarpine. In 2008 we reviewed how, following systemic injection of pilocarpine, the main subsequent events are the initial SE, the latent period, and the chronic epileptic state. Up to a decade ago, rats were most often employed and they were frequently analysed only behaviorally. However, the use of transgenic mice has revealed novel information regarding this animal model. Here, we review recent findings showing the existence of specific neuronal events during both latent and chronic states, and how optogenetic activation of specific cell populations modulate spontaneous seizures. We also address neuronal damage induced by pilocarpine treatment, the role of neuroinflammation, and the influence of circadian and estrous cycles. Updating these findings leads us to propose that the rodent pilocarpine model continues to represent a valuable tool for identifying the basic pathophysiology of MTLE.
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Affiliation(s)
- Maxime Lévesque
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery, McGill University, Montreal, QC, H3A 2B4, Canada
| | - Giuseppe Biagini
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena & Reggio Emilia, 41100 Modena, Italy
| | - Marco de Curtis
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milano, Italy
| | - Vadym Gnatkovsky
- Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milano, Italy; Department of Epileptology, University Hospital Bonn, 53127 Bonn, Germany
| | - Julika Pitsch
- Department of Epileptology, University Hospital Bonn, 53127 Bonn, Germany
| | - Siyan Wang
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery, McGill University, Montreal, QC, H3A 2B4, Canada
| | - Massimo Avoli
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery, McGill University, Montreal, QC, H3A 2B4, Canada; Departments of Physiology, McGill University, Montreal, QC, H3A 2B4, Canada; Department of Experimental Medicine, Sapienza University of Rome, 00185 Roma, Italy.
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15
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Gore A, Neufeld-Cohen A, Egoz I, Baranes S, Gez R, Efrati R, David T, Dekel Jaoui H, Yampolsky M, Grauer E, Chapman S, Lazar S. Neuroprotection by delayed triple therapy following sarin nerve agent insult in the rat. Toxicol Appl Pharmacol 2021; 419:115519. [PMID: 33823148 DOI: 10.1016/j.taap.2021.115519] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/25/2021] [Accepted: 04/01/2021] [Indexed: 02/08/2023]
Abstract
The development of refractory status epilepticus (SE) induced by sarin intoxication presents a therapeutic challenge. In our current research we evaluate the efficacy of a delayed combined triple treatment in ending the abnormal epileptiform seizure activity (ESA) and the ensuing of long-term neuronal insult. SE was induced in male Sprague-Dawley rats by exposure to 1.2LD50 sarin insufficiently treated by atropine and TMB4 (TA) 1 min later. Triple treatment of ketamine, midazolam and valproic acid was administered 30 min or 1 h post exposure and was compared to a delayed single treatment with midazolam alone. Toxicity and electrocorticogram activity were monitored during the first week and behavioral evaluation performed 3 weeks post exposure followed by brain biochemical and immunohistopathological analyses. The addition of both single and triple treatments reduced mortality and enhanced weight recovery compared to the TA-only treated group. The triple treatment also significantly minimized the duration of the ESA, reduced the sarin-induced increase in the neuroinflammatory marker PGE2, the brain damage marker TSPO, decreased the gliosis, astrocytosis and neuronal damage compared to the TA+ midazolam or only TA treated groups. Finally, the triple treatment eliminated the sarin exposed increased open field activity, as well as impairing recognition memory as seen in the other experimental groups. The delayed triple treatment may serve as an efficient therapy, which prevents brain insult propagation following sarin-induced refractory SE, even if treatment is postponed for up to 1 h.
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Affiliation(s)
- Ariel Gore
- Department of Pharmacology, Israel Institute for Biological, Chemical and Environmental Sciences, Ness-Ziona 74100, Israel.
| | - Adi Neufeld-Cohen
- Department of Pharmacology, Israel Institute for Biological, Chemical and Environmental Sciences, Ness-Ziona 74100, Israel
| | - Inbal Egoz
- Department of Pharmacology, Israel Institute for Biological, Chemical and Environmental Sciences, Ness-Ziona 74100, Israel
| | - Shlomi Baranes
- Department of Pharmacology, Israel Institute for Biological, Chemical and Environmental Sciences, Ness-Ziona 74100, Israel
| | - Rellie Gez
- Department of Pharmacology, Israel Institute for Biological, Chemical and Environmental Sciences, Ness-Ziona 74100, Israel
| | - Rahav Efrati
- Department of Pharmacology, Israel Institute for Biological, Chemical and Environmental Sciences, Ness-Ziona 74100, Israel
| | - Tse'ela David
- The Veterinary Center for Pre-clinical Research, Israel Institute for Biological, Chemical and Environmental Sciences, Ness- Ziona 74100, Israel
| | - Hani Dekel Jaoui
- The Veterinary Center for Pre-clinical Research, Israel Institute for Biological, Chemical and Environmental Sciences, Ness- Ziona 74100, Israel
| | - Michael Yampolsky
- The Veterinary Center for Pre-clinical Research, Israel Institute for Biological, Chemical and Environmental Sciences, Ness- Ziona 74100, Israel
| | - Ettie Grauer
- Department of Pharmacology, Israel Institute for Biological, Chemical and Environmental Sciences, Ness-Ziona 74100, Israel
| | - Shira Chapman
- Department of Pharmacology, Israel Institute for Biological, Chemical and Environmental Sciences, Ness-Ziona 74100, Israel
| | - Shlomi Lazar
- Department of Pharmacology, Israel Institute for Biological, Chemical and Environmental Sciences, Ness-Ziona 74100, Israel.
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16
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Reddy DS, Zaayman M, Kuruba R, Wu X. Comparative profile of refractory status epilepticus models following exposure of cholinergic agents pilocarpine, DFP, and soman. Neuropharmacology 2021; 191:108571. [PMID: 33878303 DOI: 10.1016/j.neuropharm.2021.108571] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 03/24/2021] [Accepted: 04/13/2021] [Indexed: 12/12/2022]
Abstract
Status epilepticus (SE) is a medical emergency with continuous seizure activity that causes profound neuronal damage, morbidity, or death. SE incidents can arise spontaneously but mostly are elicited by seizurogenic triggers. Chemoconvulsants such as the muscarinic agonist pilocarpine and, organophosphates (OP) such as the pesticide diisopropylfluorophosphate (DFP) and, the nerve agent soman, can induce SE. Pilocarpine, DFP, and soman share a common feature of cholinergic crisis that transitions into a state of refractory SE, but their comparative profiles remain unclear. Here, we evaluated the comparative convulsant profile of pilocarpine, DFP, and soman to produce refractory SE and brain damage in rats. Behavioral and electrographic seizures were monitored for 24 h after exposure, and the extent of brain injury was determined by histological markers of neuronal injury and degeneration. Seizures were elicited rather slowly after pilocarpine as compared to DFP or soman, which caused rapid onset of spiking that swiftly developed into persistent SE. Time-course of SE activity after DFP was comparable to that after soman, a potent nerve agent. Diazepam controlled pilocarpine-induced SE, but it was ineffective in reducing OP-induced SE. All three agents produced modestly different degrees of neuronal injury and neurodegeneration in the brain. These results reveal distinct convulsant and neuronal injury patterns following exposure to cholinergic agonists, OP pesticides, and nerve agents. A battery of SE models, especially SE induced by cholinergic agents and other etiologies including epilepsy and brain tumors, is essential to identify novel anticonvulsant therapies for the management of refractory SE.
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Affiliation(s)
- Doodipala Samba Reddy
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University Health Science Center College of Medicine, Bryan, TX, 77807, USA.
| | - Marcus Zaayman
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University Health Science Center College of Medicine, Bryan, TX, 77807, USA
| | - Ramkumar Kuruba
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University Health Science Center College of Medicine, Bryan, TX, 77807, USA
| | - Xin Wu
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University Health Science Center College of Medicine, Bryan, TX, 77807, USA
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17
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Effects of Dizocilpine, Midazolam and Their Co-Application on the Trimethyltin (TMT)-Induced Rat Model of Cognitive Deficit. Brain Sci 2021; 11:brainsci11030400. [PMID: 33809889 PMCID: PMC8004281 DOI: 10.3390/brainsci11030400] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 03/10/2021] [Accepted: 03/18/2021] [Indexed: 12/20/2022] Open
Abstract
Research of treatment options addressing the cognitive deficit associated with neurodegenerative disorders is of particular importance. Application of trimethyltin (TMT) to rats represents a promising model replicating multiple relevant features of such disorders. N-methyl-D-aspartate (NMDA) receptor antagonists and gamma-aminobutyric acid type A (GABAA) receptor potentiators have been reported to alleviate the TMT-induced cognitive deficit. These compounds may provide synergistic interactions in other models. The aim of this study was to investigate, whether co-application of NMDA receptor antagonist dizocilpine (MK-801) and GABAA receptor potentiator midazolam would be associated with an improved effect on the TMT-induced model of cognitive deficit. Wistar rats injected with TMT were repeatedly (12 days) treated with MK-801, midazolam, or both. Subsequently, cognitive performance was assessed. Finally, after a 17-day drug-free period, hippocampal neurodegeneration (neuronal density in CA2/3 subfield in the dorsal hippocampus, dentate gyrus morphometry) were analyzed. All three protective treatments induced similar degree of therapeutic effect in Morris water maze. The results of histological analyses were suggestive of minor protective effect of the combined treatment (MK-801 and midazolam), while these compounds alone were largely ineffective at this time point. Therefore, in terms of mitigation of cognitive deficit, the combined treatment was not associated with improved effect.
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18
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Charalambous M, Volk HA, Van Ham L, Bhatti SFM. First-line management of canine status epilepticus at home and in hospital-opportunities and limitations of the various administration routes of benzodiazepines. BMC Vet Res 2021; 17:103. [PMID: 33663513 PMCID: PMC7934266 DOI: 10.1186/s12917-021-02805-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 02/16/2021] [Indexed: 12/22/2022] Open
Affiliation(s)
- Marios Charalambous
- Small Animal Department, Faculty of Veterinary Medicine, Ghent University, 9820, Merelbeke, Belgium.
| | - Holger A Volk
- Department of Small Animal Medicine and Surgery, University of Veterinary Medicine Hannover, 30559, Hannover, Germany
| | - Luc Van Ham
- Small Animal Department, Faculty of Veterinary Medicine, Ghent University, 9820, Merelbeke, Belgium
| | - Sofie F M Bhatti
- Small Animal Department, Faculty of Veterinary Medicine, Ghent University, 9820, Merelbeke, Belgium
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19
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Lumley L, Niquet J, Marrero-Rosado B, Schultz M, Rossetti F, de Araujo Furtado M, Wasterlain C. Treatment of acetylcholinesterase inhibitor-induced seizures with polytherapy targeting GABA and glutamate receptors. Neuropharmacology 2021; 185:108444. [PMID: 33359073 PMCID: PMC7944923 DOI: 10.1016/j.neuropharm.2020.108444] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 10/30/2020] [Accepted: 12/17/2020] [Indexed: 12/12/2022]
Abstract
The initiation and maintenance of cholinergic-induced status epilepticus (SE) are associated with decreased synaptic gamma-aminobutyric acid A receptors (GABAAR) and increased N-methyl-d-aspartate receptors (NMDAR) and amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPAR). We hypothesized that trafficking of synaptic GABAAR and glutamate receptors is maladaptive and contributes to the pharmacoresistance to antiseizure drugs; targeting these components should ameliorate the pathophysiological consequences of refractory SE (RSE). We review studies of rodent models of cholinergic-induced SE, in which we used a benzodiazepine allosteric GABAAR modulator to correct loss of inhibition, concurrent with the NMDA antagonist ketamine to reduce excitation caused by increased synaptic localization of NMDAR and AMPAR, which are NMDAR-dependent. Models included lithium/pilocarpine-induced SE in rats and soman-induced SE in rats and in Es1-/- mice, which similar to humans lack plasma carboxylesterase, and may better model soman toxicity. These model human soman toxicity and are refractory to benzodiazepines administered at 40 min after seizure onset, when enough synaptic GABAAR may not be available to restore inhibition. Ketamine-midazolam combination reduces seizure severity, epileptogenesis, performance deficits and neuropathology following cholinergic-induced SE. Supplementing that treatment with valproate, which targets a non-benzodiazepine site, effectively terminates RSE, providing further benefit against cholinergic-induced SE. The therapeutic index of drug combinations is also reviewed and we show the improved efficacy of simultaneous administration of midazolam, ketamine and valproate compared to sequential drug administration. These data suggest that future clinical trials should treat both the lack of sufficient inhibition and the excess excitation that characterize RSE, and include early combination drug therapies. This article is part of the special issue entitled 'Acetylcholinesterase Inhibitors: From Bench to Bedside to Battlefield'.
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Affiliation(s)
- Lucille Lumley
- Neuroscience Department, US Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, MD, USA.
| | - Jerome Niquet
- Department of Neurology, David Geffen School of Medicine at UCLA, Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Brenda Marrero-Rosado
- Neuroscience Department, US Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, MD, USA
| | - Mark Schultz
- Neuroscience Department, US Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, MD, USA
| | - Franco Rossetti
- Military Psychiatry and Neuroscience Department, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | | | - Claude Wasterlain
- Department of Neurology, David Geffen School of Medicine at UCLA, Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
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20
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Marrero-Rosado BM, Stone MF, de Araujo Furtado M, Schultz CR, Cadieux CL, Lumley LA. Novel Genetically Modified Mouse Model to Assess Soman-Induced Toxicity and Medical Countermeasure Efficacy: Human Acetylcholinesterase Knock-in Serum Carboxylesterase Knockout Mice. Int J Mol Sci 2021; 22:1893. [PMID: 33672922 PMCID: PMC7918218 DOI: 10.3390/ijms22041893] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 02/06/2021] [Accepted: 02/10/2021] [Indexed: 12/13/2022] Open
Abstract
The identification of improved medical countermeasures against exposure to chemical warfare nerve agents (CWNAs), a class of organophosphorus compounds, is dependent on the choice of animal model used in preclinical studies. CWNAs bind to acetylcholinesterase and prevent the catalysis of acetylcholine, causing a plethora of peripheral and central physiologic manifestations, including seizure. Rodents are widely used to elucidate the effects of CWNA-induced seizure, albeit with a caveat: they express carboxylesterase activity in plasma. Carboxylesterase, an enzyme involved in the detoxification of some organophosphorus compounds, plays a scavenging role and decreases CWNA availability, thus exerting a protective effect. Furthermore, species-specific amino acid differences in acetylcholinesterase confound studies that use oximes or other compounds to restore its function after inhibition by CWNA. The creation of a human acetylcholinesterase knock-in/serum carboxylesterase knockout (C57BL/6-Ces1ctm1.1LocAChEtm1.1Loc/J; a.k.a KIKO) mouse may facilitate better modeling of CWNA toxicity in a small rodent species. The current studies characterize the effects of exposure to soman, a highly toxic CWNA, and evaluate the efficacy of anti-seizure drugs in this newly developed KIKO mouse model. Data demonstrate that a combination of midazolam and ketamine reduces seizure duration and severity, eliminates the development of spontaneous recurrent seizures, and protects certain brain regions from neuronal damage in a genetically modified model with human relevance to organophosphorus compound toxicity. This new animal model and the results of this study and future studies using it will enhance medical countermeasures development for both defense and homeland security purposes.
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Affiliation(s)
- Brenda M. Marrero-Rosado
- Medical Toxicology Research Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, USA; (B.M.M.-R.); (M.F.S.); (C.R.S.); (C.L.C.)
| | - Michael F. Stone
- Medical Toxicology Research Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, USA; (B.M.M.-R.); (M.F.S.); (C.R.S.); (C.L.C.)
| | - Marcio de Araujo Furtado
- Anatomy, Physiology and Genetics Department, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA;
- BioSEaD, LLC, Rockville, MD 20850, USA
| | - Caroline R. Schultz
- Medical Toxicology Research Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, USA; (B.M.M.-R.); (M.F.S.); (C.R.S.); (C.L.C.)
| | - C. Linn Cadieux
- Medical Toxicology Research Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, USA; (B.M.M.-R.); (M.F.S.); (C.R.S.); (C.L.C.)
| | - Lucille A. Lumley
- Medical Toxicology Research Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, USA; (B.M.M.-R.); (M.F.S.); (C.R.S.); (C.L.C.)
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21
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Meziane-Tani A, Foreman B, Mizrahi MA. Status Epilepticus: Work-Up and Management in Adults. Semin Neurol 2020; 40:652-660. [PMID: 33176372 DOI: 10.1055/s-0040-1719112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Status epilepticus is one of the most common neurological emergencies and is likely to have increasing prevalence in coming years given an aging "baby boomer" population in the United States. Because status epilepticus is associated with significant morbidity and mortality, identification and treatment are paramount. Care should be taken to exclude nonorganic mimics and infectious and metabolic causes. Status epilepticus can be classified into stages with associated recommendations for escalation in therapy, increasing from push-dose benzodiazepines to continuous anesthetic infusions and other nontraditional therapies. Concurrent electroencephalogram monitoring helps to identify, localize, and assess resolution of ictal patterns alongside antiseizure drug administration. A protocol is proposed for the management of status epilepticus in a step-wise fashion.
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Affiliation(s)
- Assia Meziane-Tani
- Division of Neurocritical Care, Department of Neurology, University of Cincinnati Academic Health Center, Cincinnati, Ohio
| | - Brandon Foreman
- Division of Neurocritical Care, Department of Neurology, University of Cincinnati Academic Health Center, Cincinnati, Ohio
| | - Moshe A Mizrahi
- Division of Neurocritical Care, Department of Neurology, University of Cincinnati Academic Health Center, Cincinnati, Ohio
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Marrero-Rosado BM, de Araujo Furtado M, Kundrick ER, Walker KA, Stone MF, Schultz CR, Nguyen DA, Lumley LA. Ketamine as adjunct to midazolam treatment following soman-induced status epilepticus reduces seizure severity, epileptogenesis, and brain pathology in plasma carboxylesterase knockout mice. Epilepsy Behav 2020; 111:107229. [PMID: 32575012 PMCID: PMC7541728 DOI: 10.1016/j.yebeh.2020.107229] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 06/03/2020] [Accepted: 06/04/2020] [Indexed: 12/18/2022]
Abstract
Delayed treatment of cholinergic seizure results in benzodiazepine-refractory status epilepticus (SE) that is thought, at least in part, to result from maladaptive trafficking of N-methyl-d-aspartate (NMDA) and gamma-aminobutyric acid type A (GABAA) receptors, the effects of which may be ameliorated by combination therapy with the NMDA receptor antagonist ketamine. Our objective was to establish whether ketamine and midazolam dual therapy would improve outcome over midazolam monotherapy following soman (GD) exposure when evaluated in a mouse model that, similar to humans, lacks plasma carboxylesterase, greatly reducing endogenous scavenging of GD. In the current study, continuous cortical electroencephalographic activity was evaluated in male and female plasma carboxylesterase knockout mice exposed to a seizure-inducing dose of GD and treated with midazolam or with midazolam and ketamine combination at 40 min after seizure onset. Ketamine and midazolam combination reduced GD-induced lethality, seizure severity, and the number of mice that developed spontaneous recurrent seizure (SRS) compared with midazolam monotherapy. In addition, ketamine-midazolam combination treatment reduced GD-induced neuronal degeneration and microgliosis. These results support that combination of antiepileptic drug therapies aimed at correcting the maladaptive GABAA and NMDA receptor trafficking reduces the detrimental effects of GD exposure. Ketamine may be a beneficial adjunct to midazolam in reducing the epileptogenesis and neuroanatomical damage that follows nerve agent exposure and pharmacoresistant SE.
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Affiliation(s)
- Brenda M. Marrero-Rosado
- U.S. Army Medical Research Institute of Chemical Defense, 8350 Ricketts Point Road, Aberdeen Proving Ground, MD 21010
| | - Marcio de Araujo Furtado
- Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814,BioSEaD, LLC. 451 Hungerford Drive, Rockville, MD, 20850
| | - Erica R. Kundrick
- U.S. Army Medical Research Institute of Chemical Defense, 8350 Ricketts Point Road, Aberdeen Proving Ground, MD 21010
| | - Katie A. Walker
- U.S. Army Medical Research Institute of Chemical Defense, 8350 Ricketts Point Road, Aberdeen Proving Ground, MD 21010
| | - Michael F. Stone
- U.S. Army Medical Research Institute of Chemical Defense, 8350 Ricketts Point Road, Aberdeen Proving Ground, MD 21010
| | - Caroline R. Schultz
- U.S. Army Medical Research Institute of Chemical Defense, 8350 Ricketts Point Road, Aberdeen Proving Ground, MD 21010
| | - Donna A. Nguyen
- U.S. Army Medical Research Institute of Chemical Defense, 8350 Ricketts Point Road, Aberdeen Proving Ground, MD 21010
| | - Lucille A. Lumley
- U.S. Army Medical Research Institute of Chemical Defense, 8350 Ricketts Point Road, Aberdeen Proving Ground, MD 21010
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Ionotropic Glutamate Receptors in Epilepsy: A Review Focusing on AMPA and NMDA Receptors. Biomolecules 2020; 10:biom10030464. [PMID: 32197322 PMCID: PMC7175173 DOI: 10.3390/biom10030464] [Citation(s) in RCA: 127] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/13/2020] [Accepted: 03/14/2020] [Indexed: 12/22/2022] Open
Abstract
It is widely accepted that glutamate-mediated neuronal hyperexcitation plays a causative role in eliciting seizures. Among glutamate receptors, the roles of N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors in physiological and pathological conditions represent major clinical research targets. It is well known that agonists of NMDA or AMPA receptors can elicit seizures in animal or human subjects, while antagonists have been shown to inhibit seizures in animal models, suggesting a potential role for NMDA and AMPA receptor antagonists in anti-seizure drug development. Several such drugs have been evaluated in clinical studies; however, the majority, mainly NMDA-receptor antagonists, failed to demonstrate adequate efficacy and safety for therapeutic use, and only an AMPA-receptor antagonist, perampanel, has been approved for the treatment of some forms of epilepsy. These results suggest that a misunderstanding of the role of each glutamate receptor in the ictogenic process may underlie the failure of these drugs to demonstrate clinical efficacy and safety. Accumulating knowledge of both NMDA and AMPA receptors, including pathological gene mutations, roles in autoimmune epilepsy, and evidence from drug-discovery research and pharmacological studies, may provide valuable information enabling the roles of both receptors in ictogenesis to be reconsidered. This review aimed to integrate information from several studies in order to further elucidate the specific roles of NMDA and AMPA receptors in epilepsy.
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Neurobiology of organophosphate-induced seizures. Epilepsy Behav 2019; 101:106426. [PMID: 31399343 DOI: 10.1016/j.yebeh.2019.07.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 07/05/2019] [Accepted: 07/07/2019] [Indexed: 11/24/2022]
Abstract
This review summarizes the efforts of our laboratories to develop a mechanism-based therapy for the treatment of organophosphate (OP) nerve agent-induced seizures. Organophosphate poisoning can occur during warfare and terrorist attacks and in the civilian sphere because of intentional or unintentional poisoning. Persons exposed to OPs experience seizures. We developed animal models of OP poisoning and then evaluated the effects of OP on excitatory α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-mediated glutamatergic neurotransmission in the hippocampus using patch-clamp electrophysiology. Organophosphate agents enhance glutamatergic transmission by enhancing neurotransmitter release. M1 muscarinic receptors mediate this effect, at least in part. Muscarinic receptors exert this action by inhibiting specific KCNQ2/3 potassium channels, which mediate the M-current. Flupirtine, a drug that open channels, is effective against OP-induced seizures. This article is part of the Special Issue"Proceedings of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures".
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Adotevi N, Lewczuk E, Sun H, Joshi S, Dabrowska N, Shan S, Williamson J, Kapur J. α-Amino-3-Hydroxy-5-Methyl-4-Isoxazolepropionic Acid Receptor Plasticity Sustains Severe, Fatal Status Epilepticus. Ann Neurol 2019; 87:84-96. [PMID: 31675128 DOI: 10.1002/ana.25635] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 10/30/2019] [Accepted: 10/30/2019] [Indexed: 01/06/2023]
Abstract
OBJECTIVE Generalized convulsive status epilepticus is associated with high mortality. We tested whether α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor plasticity plays a role in sustaining seizures, seizure generalization, and mortality observed during focal onset status epilepticus. We also determined whether modified AMPA receptors generated during status epilepticus could be targeted with a drug. METHODS Electrically induced status epilepticus was characterized by electroencephalogram and behavior in GluA1 knockout mice and in transgenic mice with selective knockdown of the GluA1 subunit in hippocampal principal neurons. Excitatory and inhibitory synaptic transmission in CA1 neurons was studied using patch clamp electrophysiology. The dose response of N,N,H,-trimethyl-5-([tricyclo(3.3.1.13,7)dec-1-ylmethyl]amino)-1-pentanaminiumbromide hydrobromide (IEM-1460), a calcium-permeable AMPA receptor antagonist, was determined. RESULTS Global removal of the GluA1 subunit did not affect seizure susceptibility; however, it reduced susceptibility to status epilepticus. GluA1 subunit knockout also reduced mortality, severity, and duration of status epilepticus. Absence of the GluA1 subunit prevented enhancement of glutamatergic synaptic transmission associated with status epilepticus; however, γ-aminobutyric acidergic synaptic inhibition was compromised. Selective removal of the GluA1 subunit from hippocampal principal neurons also reduced mortality, severity, and duration of status epilepticus. IEM-1460 rapidly terminated status epilepticus in a dose-dependent manner. INTERPRETATION AMPA receptor plasticity mediated by the GluA1 subunit plays a critical role in sustaining and amplifying seizure activity and contributes to mortality. Calcium-permeable AMPA receptors modified during status epilepticus can be inhibited to terminate status epilepticus. ANN NEUROL 2020;87:84-96.
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Affiliation(s)
- Nadia Adotevi
- Department of Neurology, University of Virginia, Charlottesville, VA
| | - Ewa Lewczuk
- Department of Neurology, University of Virginia, Charlottesville, VA
| | - Huayu Sun
- Department of Neurology, University of Virginia, Charlottesville, VA
| | - Suchitra Joshi
- Department of Neurology, University of Virginia, Charlottesville, VA
| | - Natalia Dabrowska
- Department of Neurology, University of Virginia, Charlottesville, VA
| | - Sarah Shan
- College of Arts and Sciences, University of Virginia, Charlottesville, VA
| | - John Williamson
- Department of Neurology, University of Virginia, Charlottesville, VA
| | - Jaideep Kapur
- Department of Neurology, University of Virginia, Charlottesville, VA.,Department of Neuroscience, University of Virginia, Charlottesville, VA.,UVA Brain Institute, University of Virginia, Charlottesville, VA
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Wang S, Lévesque M, Avoli M. Effects of Diazepam and Ketamine on Pilocarpine-Induced Status Epilepticus in Mice. Neuroscience 2019; 421:112-122. [PMID: 31704492 DOI: 10.1016/j.neuroscience.2019.10.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 10/02/2019] [Accepted: 10/03/2019] [Indexed: 02/07/2023]
Abstract
Status epilepticus (SE) is a life-threatening condition needing immediate care to prevent brain damage. SE with electrographic and behavioral features similar to those seen in humans is reproduced in rodents by i.p. pilocarpine injection, and can be terminated by diazepam and ketamine treatment but only behaviourally, not electrographically. Little is known on the behavioral and EEG effects induced by a delayed administration of ketamine (25 mg/kg) after diazepam (10 mg/kg) or vice versa. Therefore, we analysed behavior and EEG activity recorded from the mouse hippocampal CA3 region before, during SE and after anticonvulsant treatments. In the first group (n = 4), diazepam was administered one hour before ketamine whereas in the second group (n = 4) ketamine was administered one hour before diazepam. The EEG SE did not disappear after each of the two treatments but progressed within 4 h to a pattern of interictal discharges. However, diazepam administration before ketamine significantly shortened the time of behavioral recovery compared to when ketamine was administered before diazepam (p < 0.05). The two protocols were also associated to distinct EEG changes in gamma and high frequency oscillations. In conclusion, although diazepam and ketamine are not effective in stopping EEG SE, diazepam administration one hour before ketamine shortens behavioral recovery in pilocarpine-treated mice.
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Affiliation(s)
- Siyan Wang
- Montreal Neurological Institute and Departments of Neurology & Neurosurgery, and of Physiology, McGill University, 3801 University Street, Montréal, Qc H3A 2B4, Canada
| | - Maxime Lévesque
- Montreal Neurological Institute and Departments of Neurology & Neurosurgery, and of Physiology, McGill University, 3801 University Street, Montréal, Qc H3A 2B4, Canada
| | - Massimo Avoli
- Montreal Neurological Institute and Departments of Neurology & Neurosurgery, and of Physiology, McGill University, 3801 University Street, Montréal, Qc H3A 2B4, Canada.
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Prisco L, Ganau M, Aurangzeb S, Moswela O, Hallett C, Raby S, Fitzgibbon K, Kearns C, Sen A. A pragmatic approach to intravenous anaesthetics and electroencephalographic endpoints for the treatment of refractory and super-refractory status epilepticus in critical care. Seizure 2019; 75:153-164. [PMID: 31623937 DOI: 10.1016/j.seizure.2019.09.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 09/23/2019] [Indexed: 12/13/2022] Open
Abstract
Status epilepticus is a common neurological emergency, with overall mortality around 20%. Over half of cases are first time presentations of seizures. The pathological process by which spontaneous seizures are generated arises from an imbalance in excitatory and inhibitory neuronal networks, which if unchecked, can result in alterations in intracellular signalling pathways and electrolyte shifts, which bring about changes in the blood brain barrier, neuronal cell death and eventually cerebral atrophy. This narrative review focusses on the treatment of status epilepticus in adults. Anaesthetic agents interrupt neuronal activity by enhancing inhibitory or decreasing excitatory transmission, primarily via GABA and NMDA receptors. Intravenous anaesthetic agents are commonly used as second or third line drugs in the treatment of refractory status epilepticus, but the optimal timing and choice of anaesthetic drug has not yet been established by high quality evidence. Titration of antiepileptic and anaesthetic drugs in critically ill patients presents a particular challenge, due to alterations in drug absorbtion and metabolism as well as changes in drug distrubution, which arise from fluid shifts and altered protein binding. Furthermore, side effects associated with prolonged infusions of anaesthetic drugs can lead to multi-organ dysfunction and a need for critical care support. Electroencelography can identify patterns of burst suppression, which may be a target to guide weaning of intravenous therapy. Continuous elctroencephalography has the potential to directly impact clinical care, but despite its utility, major barriers exist which have limited its widespread use in clinical practice. A flow chart outlining the timing and dosage of anaesthetic agents used at our institution is provided.
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Affiliation(s)
- Lara Prisco
- Neurosciences Intensive Care Unit, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK; Anaesthesia Neuroimaging Research Group, Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK; Oxford Epilepsy Research Group, Nuffield Department of Clinical Neurosciences, University of Oxford, UK.
| | - Mario Ganau
- Department of Neurosurgery, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Sidra Aurangzeb
- Oxford Epilepsy Research Group, Nuffield Department of Clinical Neurosciences, University of Oxford, UK; Department of Clinical Neurology, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK; Department of Clinical Neurophysiology, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Olivia Moswela
- Pharmacy Department, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Claire Hallett
- Pharmacy Department, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Simon Raby
- Neurosciences Intensive Care Unit, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Karina Fitzgibbon
- Neurosciences Intensive Care Unit, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Christopher Kearns
- Neurosciences Intensive Care Unit, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Arjune Sen
- Oxford Epilepsy Research Group, Nuffield Department of Clinical Neurosciences, University of Oxford, UK; Department of Clinical Neurology, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
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Moffett MC, Rauscher NA, Rice NC, Myers TM. Survey of drug therapies against acute oral tetramethylenedisulfotetramine poisoning in a rat voluntary consumption model. Neurotoxicology 2019; 74:264-271. [DOI: 10.1016/j.neuro.2019.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 07/30/2019] [Accepted: 08/05/2019] [Indexed: 12/12/2022]
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Lévesque M, Chen LY, Etter G, Shiri Z, Wang S, Williams S, Avoli M. Paradoxical effects of optogenetic stimulation in mesial temporal lobe epilepsy. Ann Neurol 2019; 86:714-728. [PMID: 31393618 DOI: 10.1002/ana.25572] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 07/31/2019] [Accepted: 08/04/2019] [Indexed: 12/19/2022]
Abstract
OBJECTIVE To establish the effects induced by long-term, unilateral stimulation of parvalbumin (PV)-positive interneurons on seizures, interictal spikes, and high-frequency oscillations (80-500Hz) occurring after pilocarpine-induced status epilepticus (SE)-a proven model of mesial temporal lobe epilepsy (MTLE)-in transgenic mice expressing or not expressing ChR2. METHODS PV-ChR2 (n = 6) and PV-Cre (n = 6) mice were treated with pilocarpine to induce SE. Three hours after SE onset, unilateral optogenetic stimulation (450nm, 25mW, 20-millisecond pulses delivered at 8Hz for 30 seconds every 2 minutes) of CA3 PV-positive interneurons was implemented for 14 continuous days in both groups. RESULTS Rates of seizures (p < 0.01), interictal spikes (p < 0.001), and interictal spikes with fast ripples (250-500Hz) (p < 0.001) were lower in PV-ChR2 than in PV-Cre mice. Ripples (80-200Hz) occurring outside of interictal spikes had higher rates in the PV-ChR2 group (p < 0.01), whereas isolated fast ripples had lower rates (p < 0.01). However, seizure probability was higher during optogenetic stimulation in PV-ChR2 compared to PV-Cre animals (p < 0.05). INTERPRETATION Our findings show that the unilateral activation of CA3 PV-positive interneurons exerts anti-ictogenic effects associated with decreased rates of interictal spikes and fast ripples in this MTLE model. However, PV-positive interneuron stimulation can paradoxically trigger seizures in epileptic animals, supporting the notion that γ-aminobutyric acid type A signaling can also initiate ictogenesis. ANN NEUROL 2019;86:714-728.
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Affiliation(s)
- Maxime Lévesque
- Montreal Neurological Institute and Department of Neurology and Neurosurgery, and Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Li-Yuan Chen
- Montreal Neurological Institute and Department of Neurology and Neurosurgery, and Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Guillaume Etter
- Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada
| | - Zahra Shiri
- Montreal Neurological Institute and Department of Neurology and Neurosurgery, and Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Siyan Wang
- Montreal Neurological Institute and Department of Neurology and Neurosurgery, and Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Sylvain Williams
- Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada
| | - Massimo Avoli
- Montreal Neurological Institute and Department of Neurology and Neurosurgery, and Department of Physiology, McGill University, Montreal, Quebec, Canada
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Niquet J, Lumley L, Baldwin R, Rossetti F, Suchomelova L, Naylor D, Estrada IBF, Schultz M, Furtado MDA, Wasterlain CG. Rational polytherapy in the treatment of cholinergic seizures. Neurobiol Dis 2019; 133:104537. [PMID: 31454548 DOI: 10.1016/j.nbd.2019.104537] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 06/25/2019] [Accepted: 07/18/2019] [Indexed: 10/26/2022] Open
Abstract
The initiation and maintenance phases of cholinergic status epilepticus (SE) are associated with maladaptive trafficking of synaptic GABAA and glutamate receptors. The resulting pharmacoresistance reflects a decrease in synaptic GABAA receptors and increase in NMDA and AMPA receptors, which tilt the balance between inhibition and excitation in favor of the latter. If these changes are important to the pathophysiology of SE, both should be treated, and blocking their consequences should have therapeutic potential. We used a model of benzodiazepine-refractory SE (RSE) (Tetz et al., 2006) and a model of soman-induced SE to test this hypothesis. Treatment of RSE with combinations of the GABAAR agonists midazolam or diazepam and the NMDAR antagonists MK-801 or ketamine terminated RSE unresponsive to high-dose monotherapy with benzodiazepines, ketamine or other antiepileptic drugs (AEDs). It also reduced RSE-associated neuronal injury, spatial memory deficits and the occurrence of spontaneous recurrent seizures (SRS), tested several weeks after SE. Treatment of sc soman-induced SE similarly showed much greater reduction of EEG power by a combination of midazolam with ketamine, compared to midazolam monotherapy. When treating late (40 min after seizure onset), there may not be enough synaptic GABAAR left to be able to restore inhibition with maximal GABAAR stimulation, and further benefit is derived from the addition of an AED which increases inhibition or reduces excitation by a non-GABAergic mechanism. The midazolam-ketamine-valproate combination is effective in terminating RSE. 3-D isobolograms demonstrate positive cooperativity between midazolam, ketamine and valproate, without any interaction between the toxicity of these drugs, so that the therapeutic index is increased by combination therapy between GABAAR agonist, NMDAR antagonist and selective AEDs. We compared this drug combination based on the receptor trafficking hypothesis to treatments based on clinical practice. The midazolam-ketamine-valproate combination is far more effective in stopping RSE than the midazolam-fosphenytoin-valproate combination inspired from clinical guidelines. Furthermore, sequential administration of midazolam, ketamine and valproate is far less effective than simultaneous treatment with the same drugs at the same dose. These data suggest that we should re-evaluate our traditional treatment of RSE, and that treatment should be based on pathophysiology. The search for a better drug has to deal with the fact that most monotherapy leaves half the problem untreated. The search for a better benzodiazepine should acknowledge the main cause of pharmacoresistance, which is loss of synaptic GABAAR. Future clinical trials should consider treating both the failure of inhibition and the runaway excitation which characterize RSE, and should include an early polytherapy arm.
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Affiliation(s)
- Jerome Niquet
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Lucille Lumley
- Neuroscience Department, US Army Medical Research Institute of Chemical Defense (USAMRICD), 8350 Ricketts Point Rd., Aberdeen Proving Ground, MD 21010, USA
| | - Roger Baldwin
- Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Franco Rossetti
- Military Psychiatry and Neuroscience Department, Walter Reed Army institute of Research, Silver Spring, MD, USA
| | - Lucie Suchomelova
- Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - David Naylor
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Ireri Betsabe Franco Estrada
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Mark Schultz
- Neuroscience Department, US Army Medical Research Institute of Chemical Defense (USAMRICD), 8350 Ricketts Point Rd., Aberdeen Proving Ground, MD 21010, USA
| | - Marcio de Araujo Furtado
- Neuroscience Department, US Army Medical Research Institute of Chemical Defense (USAMRICD), 8350 Ricketts Point Rd., Aberdeen Proving Ground, MD 21010, USA; Military Psychiatry and Neuroscience Department, Walter Reed Army institute of Research, Silver Spring, MD, USA
| | - Claude G Wasterlain
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA; Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA., USA.
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Status Epilepticus in the Neurocritical Care Unit. Neurocrit Care 2019. [DOI: 10.1017/9781107587908.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Marchionni I, Oberoi M, Soltesz I, Alexander A. Ripple-related firing of identified deep CA1 pyramidal cells in chronic temporal lobe epilepsy in mice. Epilepsia Open 2019; 4:254-263. [PMID: 31168492 PMCID: PMC6546014 DOI: 10.1002/epi4.12310] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 01/02/2019] [Accepted: 01/19/2019] [Indexed: 01/06/2023] Open
Abstract
OBJECTIVE Temporal lobe epilepsy (TLE) is often associated with memory deficits. Reactivation of memory traces in the hippocampus occurs during sharp-wave ripples (SWRs; 140-250 Hz). To better understand the mechanisms underlying high-frequency oscillations and cognitive comorbidities in epilepsy, we evaluated how rigorously identified deep CA1 pyramidal cells (dPCs) discharge during SWRs in control and TLE mice. METHODS We used the unilateral intraamygdala kainate model of TLE in video-electroencephalography (EEG) verified chronically epileptic adult mice. Local field potential and single-cell recordings were performed using juxtacellular recordings from awake control and TLE mice resting on a spherical treadmill, followed by post hoc identification of the recorded cells. RESULTS Hippocampal SWRs in TLE mice occurred with increased intraripple frequency compared to control mice. The frequency of SWR events was decreased, whereas the overall frequency of SWRs, interictal epileptiform discharges, and high-frequency ripples (250-500 Hz) together was not altered. CA1 dPCs in TLE mice showed significantly increased firing during ripples as well as between the ripple events. The strength of ripple modulation of dPC discharges increased in TLE without alteration of the preferred phase of firing during the ripple waves. SIGNIFICANCE These juxtacellular electrophysiology data obtained from identified CA1 dPCs from chronically epileptic mice are in general agreement with recent findings indicating distortion of normal firing patterns during offline SWRs as a mechanism underlying deficits in memory consolidation in epilepsy. Because the primary seizure focus in our experiments was in the amygdala and we recorded from the CA1 region, these results are also in agreement with the presence of altered high-frequency oscillations in areas of secondary seizure spread.
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Affiliation(s)
- Ivan Marchionni
- Department of Anatomy & NeurobiologyUniversity of CaliforniaIrvineCalifornia
- Department of Biomedical Sciences and Padova Neuroscience CenterUniversity of PadovaPadovaItaly
| | - Michelle Oberoi
- Department of Anatomy & NeurobiologyUniversity of CaliforniaIrvineCalifornia
- University of CaliforniaRiverside School of MedicineRiversideCalifornia
| | - Ivan Soltesz
- Department of Anatomy & NeurobiologyUniversity of CaliforniaIrvineCalifornia
- Department of NeurosurgeryStanford UniversityStanfordCalifornia
| | - Allyson Alexander
- Department of NeurosurgeryAnschutz School of MedicineUniversity of Colorado DenverAuroraColorado
- Department of NeurosurgeryChildren's Hospital ColoradoAuroraColorado
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Abstract
Patients with prolonged seizures that do not respond to intravenous benzodiazepines and a second-line anticonvulsant suffer from refractory status epilepticus and those with seizures that do not respond to continuous intravenous anesthetic anticonvulsants suffer from super-refractory status epilepticus. Both conditions are associated with significant morbidity and mortality. A strict pharmacological treatment regimen is urgently required, but the level of evidence for the available drugs is very low. Refractory complex focal status epilepticus generally does not require anesthetics, but all intravenous non-anesthetizing anticonvulsants may be used. Most descriptive data are available for levetiracetam, phenytoin and valproate. Refractory generalized convulsive status epilepticus is a life-threatening emergency, and long-term clinical consequences are eminent. Administration of intravenous anesthetics is mandatory, and drugs acting at the inhibitory gamma-aminobutyric acid (GABA)A receptor such as midazolam, propofol and thiopental/pentobarbital are recommended without preference for one of those. One in five patients with anesthetic treatment does not respond and has super-refractory status epilepticus. With sustained seizure activity, excitatory N-methyl-d-aspartate (NMDA) receptors are increasingly expressed post-synaptically. Ketamine is an antagonist at this receptor and may prove efficient in some patients at later stages. Neurosteroids such as allopregnanolone increase sensitivity at GABAA receptors; a Phase 1/2 trial demonstrated safety and tolerability, but randomized controlled data failed to demonstrate efficacy. Adjunct ketogenic diet may contribute to termination of difficult-to-treat status epilepticus. Randomized controlled trials are needed to increase evidence for treatment of refractory and super-refractory status epilepticus, but there are multiple obstacles for realization. Hitherto, prospective multicenter registries for pharmacological treatment may help to improve our knowledge.
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Affiliation(s)
- Martin Holtkamp
- Epilepsy-Center Berlin-Brandenburg, Department of Neurology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, 10117, Berlin, Germany.
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Transition from status epilepticus to interictal spiking in a rodent model of mesial temporal epilepsy. Epilepsy Res 2019; 152:73-76. [PMID: 30913455 DOI: 10.1016/j.eplepsyres.2019.03.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 02/15/2019] [Accepted: 03/09/2019] [Indexed: 11/19/2022]
Abstract
Status epilepticus (SE) is a serious, life-threatening condition requiring immediate care to prevent neuronal injury and long-term functional deficits. SE is modeled in rodents by systemic injection of chemoconvulsants such as pilocarpine, which induces EEG and behavioral activities similar to what seen in humans. Combined injection of diazepam and ketamine is commonly used to terminate SE in rodents but, to date, no study has analysed the EEG activity and behavior during SE and after diazepam + ketamine administration. We therefore performed EEG recordings from the hippocampal CA3 region of mice before and during pilocarpine-induced SE as well as for 24 h after injection of diazepam + ketamine. We found that although convulsive behavior disappeared within 5.5 min ( ± 1.12 min; n = 5) after diazepam + ketamine treatment, EEG epileptiform activity resembling what seen during SE persisted up to 278.8 min ( ± 262.0 min). The end of this SE-like EEG pattern was characterised by transition to high amplitude, persisting interictal spikes. Our findings show that (i) administration of diazepam and ketamine stops behavioral but not EEG epileptiform activity associated to pilocarpine-induced SE; and (ii) such SE-like EEG pattern persists for approx. 4 h to be replaced by interictal spikes that predominate during the so called latent period in this model of mesial temporal lobe epilepsy.
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Fujikawa DG. Starting ketamine for neuroprotection earlier than its current use as an anesthetic/antiepileptic drug late in refractory status epilepticus. Epilepsia 2019; 60:373-380. [PMID: 30785224 DOI: 10.1111/epi.14676] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 01/24/2019] [Accepted: 01/24/2019] [Indexed: 12/26/2022]
Abstract
Ketamine is currently being used as an anesthetic/antiepileptic drug in refractory status epilepticus. To validate its use, 2 clinical trials are recruiting patients. However, preclinical studies of its use in chemically induced status epilepticus in rodents have shown that it is remarkably neuroprotective, through N-methyl-d-aspartate-receptor blockade, even when given after the onset of status epilepticus. Human studies have shown that status epilepticus-induced brain damage can be caused by a glutamate analogue and that it occurs in the same brain regions as in the animal studies. We therefore propose that ketamine be started early in the course of human status epilepticus as a neuroprotectant and that it be continued until epileptic discharges are eliminated. Using it as an anesthetic/antiepileptic drug late in the course of refractory status epilepticus only ensures that it is given after widespread brain damage has occurred.
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Affiliation(s)
- Denson G Fujikawa
- Neurology Department, VA Greater Los Angeles Healthcare System, Sepulveda Ambulatory Care Center and Nursing Home, North Hills, California.,Department of Neurology and Brain Research Institute, David Geffen School of Medicine, Los Angeles, California
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Colangeli R, Di Maio R, Pierucci M, Deidda G, Casarrubea M, Di Giovanni G. Synergistic action of CB 1 and 5-HT 2B receptors in preventing pilocarpine-induced status epilepticus in rats. Neurobiol Dis 2019; 125:135-145. [PMID: 30716469 DOI: 10.1016/j.nbd.2019.01.026] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 01/24/2019] [Accepted: 01/31/2019] [Indexed: 11/30/2022] Open
Abstract
Endocannabinoids (eCBs) and serotonin (5-HT) play a neuromodulatory role in the central nervous system. Both eCBs and 5-HT regulate neuronal excitability and their pharmacological potentiation has been shown to control seizures in pre-clinical and human studies. Compelling evidence indicates that eCB and 5-HT systems interact to modulate several physiological and pathological brain functions, such as food intake, pain, drug addiction, depression, and anxiety. Nevertheless, there is no evidence of an eCB/5-HT interaction in experimental and human epilepsies, including status epilepticus (SE). Here, we performed video-EEG recording in behaving rats treated with the pro-convulsant agent pilocarpine (PILO), in order to study the effect of the activation of CB1/5-HT2 receptors and their interaction on SE. Synthetic cannabinoid agonist WIN55,212-2 (WIN) decreased behavioral seizure severity of PILO-induced SE at 2 mg/kg (but not at 1 and 5 mg/kg, i.p.), while 5-HT2B/2C receptor agonist RO60-0175 (RO; 1, 3, 10 mg/kg, i.p.) was devoid of any effect. RO 3 mg/kg was instead capable of potentiating the effect of WIN 2 mg/kg on the Racine scale score. Surprisingly, neither WIN 2 mg/kg nor RO 3 mg/kg had any effect on the incidence and the intensity of EEG seizures when administered alone. However, WIN+RO co-administration reduced the incidence and the severity of EEG SE and increased the latency to SE onset after PILO injection. WIN+RO effects were blocked by the selective CB1R antagonist AM251 and the 5-HT2BR antagonist RS127445, but not by the 5-HT2CR antagonist SB242084 or the 5-HT2AR antagonist MDL11,939. These data revealed a synergistic interaction between CB1R/5-HT2BR in the expression of PILO-induced SE.
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Affiliation(s)
- Roberto Colangeli
- Laboratory of Neurophysiology, Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta.
| | - Roberto Di Maio
- Pittsburgh Inst. for Neurodegenerative Dis., Dept. of Neurology, Univ. of Pittsburgh, PA, USA
| | - Massimo Pierucci
- Laboratory of Neurophysiology, Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta
| | - Gabriele Deidda
- Laboratory of Neurophysiology, Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta
| | - Maurizio Casarrubea
- Department of Experimental Biomedicine and Clinical Neurosciences, Human Physiology Section "Giuseppe Pagano", University of Palermo, Palermo, Italy
| | - Giuseppe Di Giovanni
- Laboratory of Neurophysiology, Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta; School of Biosciences, Cardiff University, Cardiff, UK.
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Abstract
BACKGROUND Ketamine is an emerging third-line medication for refractory status epilepticus, a medical and neurological emergency requiring prompt and appropriate treatment. Owing to its pharmacological properties, ketamine represents a practical alternative to conventional anaesthetics. OBJECTIVE The objective of this study was to assess the efficacy and safety of ketamine to treat refractory status epilepticus in paediatric and adult populations. METHODS We conducted a literature search using the PubMed database, Cochrane Database of Systematic Reviews and ClinicalTrials.gov website. RESULTS We found no results from randomised controlled trials. The literature included 27 case reports accounting for 30 individuals and 14 case series, six of which included children. Overall, 248 individuals (29 children) with a median age of 43.5 years (range 2 months to 67 years) were treated in 12 case series whose sample size ranged from 5 to 67 patients (median 11). Regardless of the status epilepticus type, ketamine was twice as effective if administered early, with an efficacy rate as high as 64% in refractory status epilepticus lasting 3 days and dropping to 32% when the mean refractory status epilepticus duration was 26.5 days. Ketamine doses were extremely heterogeneous and did not appear to be an independent prognostic factor. Endotracheal intubation, a negative prognostic factor for status epilepticus, was unnecessary in 12 individuals (10 children), seven of whom were treated with oral ketamine for non-convulsive status epilepticus. CONCLUSIONS Although ketamine has proven to be effective in treating refractory status epilepticus, available studies are hampered by methodological limitations that prevent any firm conclusion. Results from two ongoing studies (ClinicalTrials.gov identification number: NCT02431663 and NCT03115489) and further clinical trials will hopefully confirm the better efficacy and safety profile of ketamine compared with conventional anaesthetics as third-line therapy in refractory status epilepticus, both in paediatric and adult populations.
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Affiliation(s)
- Anna Rosati
- Neuroscience Department, Children's Hospital Anna Meyer, University of Florence, Viale Pieraccini 24, 50139, Florence, Italy
| | | | - Renzo Guerrini
- Neuroscience Department, Children's Hospital Anna Meyer, University of Florence, Viale Pieraccini 24, 50139, Florence, Italy.
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Joshi S, Kapur J. Mechanisms of status epilepticus: α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor hypothesis. Epilepsia 2018; 59 Suppl 2:78-81. [PMID: 30159880 DOI: 10.1111/epi.14482] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/03/2017] [Indexed: 02/03/2023]
Abstract
Prolonged seizures of status epilepticus (SE) result from failure of mechanisms of seizure termination or activation of mechanisms that sustain seizures. Reduced γ-aminobutyric acid type A receptor-mediated synaptic transmission contributes to impairment of seizure termination. However, mechanisms that sustain prolonged seizures are not known. We propose that insertion of GluA1 subunits at the glutamatergic synapses causes potentiation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic receptor (AMPAR)-mediated neurotransmission, which helps to spread and sustain seizures. The AMPAR-mediated neurotransmission of CA1 pyramidal neurons was increased in animals in SE induced by pilocarpine. The surface membrane expression of GluA1 subunit-containing AMPARs on CA1 pyramidal neurons was also increased. Blockade of N-methyl-d-aspartate receptors 10 minutes after the onset of continuous electrographic seizure activity prevented the increase in the surface expression of GluA1 subunits. N-methyl-d-aspartate receptor antagonist MK-801 in conjunction with diazepam also terminated seizures that were refractory to MK-801 or diazepam alone. Future studies using mice lacking the GluA1 subunit expression will provide further insights into the role of GluA1 subunit-containing AMPAR plasticity in sustaining seizures of SE.
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Affiliation(s)
- Suchitra Joshi
- Department of Neurology, University of Virginia, Charlottesville, VA, USA
| | - Jaideep Kapur
- Department of Neurology, University of Virginia, Charlottesville, VA, USA.,Department of Neuroscience, University of Virginia, Charlottesville, VA, USA.,UVA Brain Institute, University of Virginia, Charlottesville, VA, USA
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Höfler J, Trinka E. Intravenous ketamine in status epilepticus. Epilepsia 2018; 59 Suppl 2:198-206. [DOI: 10.1111/epi.14480] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2017] [Indexed: 01/03/2023]
Affiliation(s)
- Julia Höfler
- Department of Neurology; Paracelsus Medical University Salzburg and Christian Doppler Medical Center; Salzburg Austria
| | - Eugen Trinka
- Department of Neurology; Paracelsus Medical University Salzburg and Christian Doppler Medical Center; Salzburg Austria
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40
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Abstract
Status epilepticus (SE) is a medical emergency and presents with either a continuous prolonged seizure or multiple seizures without full recovery of consciousness in between them. The goals of treatment are prompt recognition, early seizure termination, and simultaneous evaluation for any potentially treatable cause. Improved understanding of the pathophysiology has led to a more practical definition. New data have emerged regarding the safety and efficacy of alternative agents, which are increasingly used in the management of these patients. Continuous electroencephalogram monitoring is more widely used and has revealed a higher incidence of subclinical seizures than was previously thought.
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Affiliation(s)
- Sudhir Datar
- Section of Neurocritical Care, Departments of Neurology and Anesthesiology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston Salem, NC 27157, USA.
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41
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Amengual-Gual M, Sánchez Fernández I, Wainwright MS. Novel drugs and early polypharmacotherapy in status epilepticus. Seizure 2018; 68:79-88. [PMID: 30473267 DOI: 10.1016/j.seizure.2018.08.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 08/05/2018] [Indexed: 12/11/2022] Open
Abstract
PURPOSE Rescue medications for status epilepticus (SE) have a relatively high rate of failure. The purpose of this review is to summarize the evidence for the efficacy of novel drugs and early polypharmacotherapy for SE. METHOD Literature review. RESULTS New drugs and treatment strategies aim to target the pathophysiology of SE in order to improve seizure control and outcomes. Changes at the synapse level during SE include a progressive decrease in synaptic GABAA receptors and increase in synaptic NMDA receptors. These changes tend to promote self-sustaining seizures. Current SE guidelines recommend a rapid stepwise treatment using benzodiazepines in monotherapy as the first-line treatment, targeting GABAA synaptic receptors. Novel treatment approaches target GABAA synaptic and extrasynaptic receptors with allopregnanolone, and NMDA receptors with ketamine. Novel rescue treatments used for SE include topiramate, brivaracetam, and perampanel, which are already marketed in epilepsy. Some available drugs not marketed for use in epilepsy have been used in the treatment of SE, and other agents are being studied for this purpose. Early polytherapy, most frequently combining a benzodiazepine with a second-line drug or an NMDA receptor antagonist, might potentially increase seizure control with relatively minor increase in side effects. Although many preclinical studies support novel drugs and early polytherapy in SE, human studies are scarce and inconclusive. Currently, evidence is lacking to recommend specific combinations of these new agents. CONCLUSIONS Novel drugs and strategies target the underlying pathophysiology of SE with the intent to improve seizure control and outcomes.
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Affiliation(s)
- Marta Amengual-Gual
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; Pediatric Neurology Unit, Department of Pediatrics, Hospital Universitari Son Espases, Universitat de les Illes Balears, Palma, Spain.
| | - Iván Sánchez Fernández
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; Department of Child Neurology, Hospital Sant Joan de Déu, Universidad de Barcelona, Spain
| | - Mark S Wainwright
- Department of Neurology, Division of Pediatric Neurology. University of Washington School of Medicine, Seattle, WA, USA
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Samiee S, Lévesque M, Avoli M, Baillet S. Phase-amplitude coupling and epileptogenesis in an animal model of mesial temporal lobe epilepsy. Neurobiol Dis 2018; 114:111-119. [PMID: 29486299 PMCID: PMC5891384 DOI: 10.1016/j.nbd.2018.02.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 02/09/2018] [Accepted: 02/21/2018] [Indexed: 10/18/2022] Open
Abstract
Polyrhythmic coupling of oscillatory components in electrophysiological signals results from the interactions between neuronal sub-populations within and between cell assemblies. Since the mechanisms underlying epileptic disorders should affect such interactions, abnormal level of cross-frequency coupling is expected to provide a signal marker of epileptogenesis. We measured phase-amplitude coupling (PAC), a form of cross-frequency coupling between neural oscillations, in a rodent model of mesial temporal lobe epilepsy. Sprague-Dawley rats (n = 4, 250-300 g) were injected with pilocarpine (380 mg/kg, i.p) to induce a status epilepticus (SE) that was stopped after 1 h with diazepam (5 mg/kg, s.c.) and ketamine (50 mg/kg, s.c.). Control animals (n = 6) did not receive any injection or treatment. Three days after SE, all animals were implanted with bipolar electrodes in the hippocampal CA3 subfield, entorhinal cortex, dentate gyrus and subiculum. Continuous video/EEG recordings were performed 24/7 at a sampling rate of 2 kHz, over 15 consecutive days. Pilocarpine-treated animals showed interictal spikes (5.25 (±2.5) per minute) and seizures (n = 32) that appeared 7 (±0.8) days after SE. We found that CA3 was the seizure onset zone in most epileptic animals, with stronger ongoing PAC coupling between seizures than in controls (Kruskal-Wallis test: chi2 (1,36) = 46.3, Bonferroni corrected, p < 0.001). Strong PAC in CA3 occurred between the phase of slow-wave oscillations (<1 Hz) and the amplitude of faster rhythms (50-180 Hz), with the strongest bouts of high-frequency activity occurring preferentially on the ascending phase of the slow wave. We also identified that cross-frequency coupling in CA3 (rho = 0.44, p < 0.001) and subiculum (rho = 0.41, p < 0.001) was positively correlated with the daily number of seizures. Overall, our study demonstrates that cross-frequency coupling may represent a signal marker in epilepsy and suggests that this methodology could be transferred to clinical scalp MEG and EEG recordings.
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Affiliation(s)
- Soheila Samiee
- Department of Neurology & Neurosurgery, Biomedical Engineering and Computer Science, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Maxime Lévesque
- Department of Neurology & Neurosurgery, Biomedical Engineering and Computer Science, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Massimo Avoli
- Department of Neurology & Neurosurgery, Biomedical Engineering and Computer Science, Montreal Neurological Institute, McGill University, Montreal, QC, Canada; Department of Neurology & Neurosurgery and of Physiology, McGill University, Montreal, QC, Canada
| | - Sylvain Baillet
- Department of Neurology & Neurosurgery, Biomedical Engineering and Computer Science, Montreal Neurological Institute, McGill University, Montreal, QC, Canada.
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Keshavarz M, Yekzaman B. Amelioration of Pentylenetetrazole-Induced Seizures by Modulators of Sigma, N-Methyl-D-Aspartate, and Ryanodine Receptors in Mice. IRANIAN JOURNAL OF MEDICAL SCIENCES 2018; 43:195-201. [PMID: 29749988 PMCID: PMC5936851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 11/19/2016] [Accepted: 12/18/2016] [Indexed: 11/23/2022]
Abstract
BACKGROUND Sigma receptors, N-methyl-D-aspartate (NMDA) antagonist, and modulators of intracellular calcium may be useful for seizure control. Therefore, we aimed to evaluate the antiepileptic effects of opipramol, a sigma receptor agonist, against pentylenetetrazole (PTZ)-induced seizures in mice and assess ketamine and caffeine interaction with the antiepileptic effects of opipramol. METHODS PTZ (100 mg/kg) was used for the induction of seizure in 72 male albino Swiss strain of mice (n=8). Opipramole (10, 20, and 50 mg/kg), ketamine (50 mg/kg), caffeine (200 mg/kg), opipramole (20 mg/kg) plus ketamine (50 mg/kg), opipramole (20 mg/kg) plus caffeine (200 mg/kg), diazepam (5 mg/kg as a positive control), and the vehicle were administered interaperitoneally 30 minutes before the injection of PTZ. The latency was recorded for the clonic, tonic-clonic seizures, and death of animals after the injection of PTZ. Kruskal-Wallis test followed by Dunn's test was used for the analysis of data. Statistical analysis was performed with the SPSS software version 23.0 and P<0.05 was considered as the significant level. RESULTS Opipramol (20 mg/kg) increased the latency for the PTZ-induced clonic (44%, P=0.021) and tonic-clonic (130.80%, P=0.043) seizures compared with the vehicle-treated group. Animals treated with opipramol (20 mg/kg) plus caffeine (200 mg/kg) had a significantly higher onset of PTZ-induced clonic and tonic-clonic seizures compared with the control (P=0.046 and <0.001, respectively). Ketamine combined with opipramol increased the onset of tonic-clonic seizure compared with the vehicle-treated groups (P<0.001). CONCLUSION Opipramol attenuated the seizures induced by the PTZ. Ketamine and caffeine had no effect on the anticonvulsant activity of opipramol.
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Affiliation(s)
- Mojtaba Keshavarz
- Department of Pharmacology, Bushehr University of Medical Sciences, Bushehr, Iran
- Shiraz Neuroscience Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Behdad Yekzaman
- School of Medicine, Bushehr University of Medical Sciences, Bushehr, Iran
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Zhang T, Todorovic MS, Williamson J, Kapur J. Flupirtine and diazepam combination terminates established status epilepticus: results in three rodent models. Ann Clin Transl Neurol 2017; 4:888-896. [PMID: 29296617 PMCID: PMC5740237 DOI: 10.1002/acn3.497] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 09/30/2017] [Accepted: 10/09/2017] [Indexed: 12/17/2022] Open
Abstract
Objective Status epilepticus (SE) is a neurological emergency requiring rapid termination of seizures. New treatment choices are needed for benzodiazepine-refractory SE or established SE (ESE). Previous studies have demonstrated that the potassium-channel opener flupirtine terminates seizures in neonatal animals. However, its effectiveness in adult ESE has not been tested. We tested whether flupirtine alone or in combination with the benzodiazepine diazepam would terminate ESE in three animal models. Methods SE was induced by administration of lithium followed by pilocarpine, by electrical stimulation of the hippocampus or by diisopropylfluorophosphate (DFP) administration. Seizures were assessed by EEG recorded from the hippocampus and cortex. Results Flupirtine alone did not terminate ESE within 60 min of administration in any of the three models of ESE. A combination of flupirtine and diazepam terminated ESE within 60 min in all the three models. The drug combination shortened the duration of ESE in all three models. Drug responsiveness was distinct between each model. Conclusion A combination of the potassium channel opener flupirtine and diazepam is a potential therapy for ESE.
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Affiliation(s)
- Terry Zhang
- Department of Neurology University of Virginia Health Sciences Center Charlottesville Virginia 22908
| | - Marko S Todorovic
- Department of Neurology University of Virginia Health Sciences Center Charlottesville Virginia 22908
| | - John Williamson
- Department of Neurology University of Virginia Health Sciences Center Charlottesville Virginia 22908
| | - Jaideep Kapur
- Department of Neurology University of Virginia Health Sciences Center Charlottesville Virginia 22908.,Department of Neuroscience University of Virginia Health Sciences Center Charlottesville Virginia 22908
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Behr C, Lévesque M, Stroh T, Avoli M. Time-dependent evolution of seizures in a model of mesial temporal lobe epilepsy. Neurobiol Dis 2017; 106:205-213. [DOI: 10.1016/j.nbd.2017.07.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 07/03/2017] [Accepted: 07/10/2017] [Indexed: 01/21/2023] Open
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Abstract
Status epilepticus (SE) is a medical emergency and presents with either a continuous prolonged seizure or multiple seizures without full recovery of consciousness in between them. The goals of treatment are prompt recognition, early seizure termination, and simultaneous evaluation for any potentially treatable cause. Improved understanding of the pathophysiology has led to a more practical definition. New data have emerged regarding the safety and efficacy of alternative agents, which are increasingly used in the management of these patients. Continuous electroencephalogram monitoring is more widely used and has revealed a higher incidence of subclinical seizures than was previously thought.
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Affiliation(s)
- Sudhir Datar
- Section of Neurocritical Care, Departments of Neurology and Anesthesiology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston Salem, NC 27157, USA.
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47
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Apland JP, Aroniadou-Anderjaska V, Figueiredo TH, Prager EM, Olsen CH, Braga MFM. Susceptibility to Soman Toxicity and Efficacy of LY293558 Against Soman-Induced Seizures and Neuropathology in 10-Month-Old Male Rats. Neurotox Res 2017; 32:694-706. [PMID: 28776308 DOI: 10.1007/s12640-017-9789-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 07/13/2017] [Accepted: 07/21/2017] [Indexed: 12/23/2022]
Abstract
Acute nerve agent exposure causes prolonged status epilepticus (SE), leading to death or long-term brain damage. We have previously demonstrated that LY293558, an AMPA/GluK1 kainate receptor antagonist, terminates SE induced by the nerve agent soman and protects from long-term brain damage, in immature rats and young-adult rats, even if administered with a relatively long latency from the time of exposure. However, susceptibility to the lethal consequences of SE increases with age, and mortality by SE induced by soman is substantially greater in older animals. Therefore, in the present study, we compared the susceptibility to soman toxicity of 10-month-old male rats with that of young-adult male rats (42 to 50 days old) and examined the protective efficacy of LY293558 in the older group. A lower percentage of the 10-month-old rats developed SE after injection of 1.2 × LD50 soman, compared to the young adults, the latency to seizure onset was longer in the older rats, and seizure intensity did not differ between the two age groups. However, mortality rate in the older rats who developed SE was higher than in the young adults. Acetylcholinesterase activity in the amygdala, hippocampus, and piriform cortex did not differ between the two age groups. Administration of LY293558 at 20 or 60 min post-exposure suppressed SE, increased 24-h survival rate, decreased the long-term risk of death, reduced neuronal degeneration in the amygdala, hippocampus, piriform, and entorhinal cortices, and facilitated recovery from body weight loss. Thus, LY293558 is an effective countermeasure against soman toxicity also in older animals.
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Affiliation(s)
- James P Apland
- Neuroscience Program, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Aberdeen, MD, 21010, USA
| | - Vassiliki Aroniadou-Anderjaska
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA.,Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
| | - Taiza H Figueiredo
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA
| | - Eric M Prager
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA.,John Wiley and Sons, Inc., 111 River Street, Hoboken, NJ, 07030, USA
| | - Cara H Olsen
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA
| | - Maria F M Braga
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA. .,Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA.
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Allopregnanolone decreases interictal spiking and fast ripples in an animal model of mesial temporal lobe epilepsy. Neuropharmacology 2017; 121:12-19. [DOI: 10.1016/j.neuropharm.2017.04.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 03/21/2017] [Accepted: 04/13/2017] [Indexed: 11/21/2022]
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Joshi S, Rajasekaran K, Sun H, Williamson J, Kapur J. Enhanced AMPA receptor-mediated neurotransmission on CA1 pyramidal neurons during status epilepticus. Neurobiol Dis 2017; 103:45-53. [PMID: 28377128 PMCID: PMC5481781 DOI: 10.1016/j.nbd.2017.03.017] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 03/29/2017] [Accepted: 03/31/2017] [Indexed: 12/20/2022] Open
Abstract
Status epilepticus (SE) is a common neurological emergency that results from the failure of the mechanisms responsible for seizure termination or the initiation of mechanisms that lead to abnormally prolonged seizures. Although the failure of inhibitory mechanisms during SE is well understood, the seizure-initiating mechanisms are poorly understood. We tested whether hippocampal α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-mediated transmission was enhanced during SE and assessed the underlying molecular mechanism. In animals in self-sustaining limbic SE the amplitudes of the miniature, spontaneous, and AMPA-evoked excitatory currents recorded from the CA1 pyramidal neurons were larger than those recorded in the controls. The evoked EPSCs rectified inwardly. In these animals, the surface expression of GluA1 subunit-containing AMPARs was increased in the CA1 pyramidal neurons. The phosphorylation of the GluA1 subunit on S831 and S845 residues was reduced in animals in SE. In contrast, the GluA1 subunit surface expression and AMPAR-mediated neurotransmission of dentate granule cells (DGCs) was not altered. Treating animals in SE with the NMDAR antagonist MK-801 or with diazaepam blocked the increased surface expression of the GluA1 subunits. NMDAR blockade also prevented the dephosphorylation of the S845 residue but not that of S831. Targeting NMDARs and AMPARs may provide novel strategies to treat benzodiazepine-refractory SE.
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Affiliation(s)
- Suchitra Joshi
- Department of Neurology, University of Virginia, Charlottesville, VA 22908, United States
| | - Karthik Rajasekaran
- Department of Neurology, University of Virginia, Charlottesville, VA 22908, United States
| | - Huayu Sun
- Department of Neurology, University of Virginia, Charlottesville, VA 22908, United States
| | - John Williamson
- Department of Neurology, University of Virginia, Charlottesville, VA 22908, United States
| | - Jaideep Kapur
- Department of Neurology, University of Virginia, Charlottesville, VA 22908, United States; Department of Neuroscience University of Virginia, Charlottesville, VA 22908, United States.
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Niquet J, Baldwin R, Norman K, Suchomelova L, Lumley L, Wasterlain CG. Simultaneous triple therapy for the treatment of status epilepticus. Neurobiol Dis 2017; 104:41-49. [PMID: 28461248 DOI: 10.1016/j.nbd.2017.04.019] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 03/27/2017] [Accepted: 04/27/2017] [Indexed: 02/08/2023] Open
Abstract
Early maladaptive internalization of synaptic GABAA receptors (GABAAR) and externalization of NMDA receptors (NMDAR) may explain the time-dependent loss of potency of standard anti-epileptic drugs (AED) in refractory status epilepticus (SE). We hypothesized that correcting the effects of changes in GABAAR and NMDAR would terminate SE, even when treatment is delayed 40 minutes. SE was induced in adult Sprague-Dawley rats with a high dose of lithium and pilocarpine. The GABAAR agonist midazolam, the NMDAR antagonist ketamine and the AED valproate were injected 40 min after SE onset in combination or as monotherapy. The midazolam-ketamine-valproate combination was more efficient than triple-dose midazolam, ketamine or valproate monotherapy or higher-dose dual therapy in reducing several parameters of SE severity. Triple therapy also reduced SE-induced acute neuronal injury and spatial memory deficits. In addition, simultaneous triple therapy was more efficient than sequential triple therapy: giving the three drugs simultaneously was more efficient at stopping seizures than the standard practice of giving them sequentially. Furthermore, midazolam-ketamine-valproate therapy suppressed seizures far better than the midazolam-fosphenytoin-valproate therapy, which follows evidence-based AES guidelines. These results show that a treatment aimed at correcting maladaptive GABAAR and NMDAR trafficking can reduce the severity of SE and its long-term consequences.
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Affiliation(s)
- Jerome Niquet
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA.
| | - Roger Baldwin
- Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Keith Norman
- Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Lucie Suchomelova
- Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Lucille Lumley
- US Army Medical Research Institute of Chemical Defense (USAMRICD), 2900 Ricketts Point Rd., Aberdeen Proving Ground, MD 21010, USA
| | - Claude G Wasterlain
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA; Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
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