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Lumley LA, Nguyen DA, de Araujo Furtado M, Niquet J, Linz EO, Schultz CR, Stone MF, Wasterlain CG. Efficacy of Lacosamide and Rufinamide as Adjuncts to Midazolam-Ketamine Treatment Against Cholinergic-Induced Status Epilepticus in Rats. J Pharmacol Exp Ther 2024; 388:347-357. [PMID: 37977809 PMCID: PMC10801783 DOI: 10.1124/jpet.123.001789] [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: 10/30/2023] [Accepted: 10/31/2023] [Indexed: 11/19/2023] Open
Abstract
Benzodiazepine pharmacoresistance develops when treatment of status epilepticus (SE) is delayed. This response may result from gamma-aminobutyric acid A receptors (GABAAR) internalization that follows prolonged SE; this receptor trafficking results in fewer GABAAR in the synapse to restore inhibition. Increase in synaptic N-methyl-D-aspartate receptors (NMDAR) also occurs in rodent models of SE. Lacosamide, a third-generation antiseizure medication (ASM), acts on the slow inactivation of voltage-gated sodium channels. Another ASM, rufinamide, similarly acts on sodium channels by extending the duration of time spent in the inactivation stage. Combination therapy of the benzodiazepine midazolam, NMDAR antagonist ketamine, and ASMs lacosamide (or rufinamide) was investigated for efficacy against soman (GD)-induced SE and neuropathology. Adult male rats implanted with telemetry transmitters for monitoring electroencephalographic (EEG) activity were exposed to a seizure-inducing dose of GD and treated with an admix of atropine sulfate and HI-6 1 minute later and with midazolam monotherapy or combination therapy 40 minutes after EEG seizure onset. Rats were monitored continuously for seizure activity for two weeks, after which brains were processed for assessment of neurodegeneration, neuronal loss, and neuroinflammatory responses. Simultaneous administration of midazolam, ketamine, and lacosamide (or rufinamide) was more protective against GD-induced SE compared with midazolam monotherapy. In general, lacosamide triple therapy had more positive outcomes on measures of epileptogenesis, EEG power integral, and the number of brain regions protected from neuropathology compared with rats treated with rufinamide triple therapy. Overall, both drugs were well tolerated in these combination models. SIGNIFICANCE STATEMENT: We currently report on improved efficacy of antiseizure medications lacosamide and rufinamide, each administered in combination with ketamine (NMDAR antagonist) and midazolam (benzodiazepine), in combatting soman (GD)-induced seizure, epileptogenesis, and brain pathology over that provided by midazolam monotherapy, or dual therapy of midazolam and lacosamide (or rufinamide) in rats. Administration of lacosamide as adjunct to midazolam and ketamine was particularly effective against GD-induced toxicity. However, protection was incomplete, suggesting the need for further study.
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Affiliation(s)
- Lucille A Lumley
- Neuroscience Department, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (L.A.L., D.A.N., E.O.L., C.R.S., M.F.S.); BioSEaD, LLC, Rockville, Maryland (M.d.A.F.); and Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California, and Epilepsy Research Laboratory, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California (J.N., C.G.W.)
| | - Donna A Nguyen
- Neuroscience Department, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (L.A.L., D.A.N., E.O.L., C.R.S., M.F.S.); BioSEaD, LLC, Rockville, Maryland (M.d.A.F.); and Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California, and Epilepsy Research Laboratory, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California (J.N., C.G.W.)
| | - Marcio de Araujo Furtado
- Neuroscience Department, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (L.A.L., D.A.N., E.O.L., C.R.S., M.F.S.); BioSEaD, LLC, Rockville, Maryland (M.d.A.F.); and Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California, and Epilepsy Research Laboratory, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California (J.N., C.G.W.)
| | - Jerome Niquet
- Neuroscience Department, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (L.A.L., D.A.N., E.O.L., C.R.S., M.F.S.); BioSEaD, LLC, Rockville, Maryland (M.d.A.F.); and Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California, and Epilepsy Research Laboratory, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California (J.N., C.G.W.)
| | - Emily O Linz
- Neuroscience Department, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (L.A.L., D.A.N., E.O.L., C.R.S., M.F.S.); BioSEaD, LLC, Rockville, Maryland (M.d.A.F.); and Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California, and Epilepsy Research Laboratory, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California (J.N., C.G.W.)
| | - Caroline R Schultz
- Neuroscience Department, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (L.A.L., D.A.N., E.O.L., C.R.S., M.F.S.); BioSEaD, LLC, Rockville, Maryland (M.d.A.F.); and Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California, and Epilepsy Research Laboratory, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California (J.N., C.G.W.)
| | - Michael F Stone
- Neuroscience Department, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (L.A.L., D.A.N., E.O.L., C.R.S., M.F.S.); BioSEaD, LLC, Rockville, Maryland (M.d.A.F.); and Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California, and Epilepsy Research Laboratory, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California (J.N., C.G.W.)
| | - Claude G Wasterlain
- Neuroscience Department, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (L.A.L., D.A.N., E.O.L., C.R.S., M.F.S.); BioSEaD, LLC, Rockville, Maryland (M.d.A.F.); and Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California, and Epilepsy Research Laboratory, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California (J.N., C.G.W.)
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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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Gage M, Vasanthi SS, Meyer CM, Rao NS, Thedens DR, Kannurpatti SS, Thippeswamy T. Sex-based structural and functional MRI outcomes in the rat brain after soman (GD) exposure-induced status epilepticus. Epilepsia Open 2023; 8:399-410. [PMID: 36718979 PMCID: PMC10235578 DOI: 10.1002/epi4.12701] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 01/25/2023] [Indexed: 02/01/2023] Open
Abstract
OBJECTIVE Exposure to the nerve agent, soman (GD), induces status epilepticus (SE), epileptogenesis, and even death. Although rodent models studying the pathophysiological mechanisms show females to be more reactive to soman, no tangible sex differences in brains postexposure have been reported. In this study, we used multimodal imaging using MRI in adult rats to determine potential sex-based biomarkers of soman effects. METHODS Male and female Sprague Dawley rats were challenged with 1.2 × LD50 soman followed by medical countermeasures. Ten weeks later, the brains were analyzed via structural and functional MRI. RESULTS Despite no significant sex differences in the initial SE severity after soman exposure, long-term MRI-based structural and functional differences were evident in the brains of both sexes. While T2 MRI showed lesser soman-induced neurodegeneration, large areas of T1 enhancements occurred in females than in males, indicating a distinct pathophysiology unrelated to neurodegeneration. fMRI-based resting-state functional connectivity (RSFC), indicated greater reductions in soman-exposed females than in males, associating with the T1 enhancements (unrelated to neurodegeneration) rather than T2-hyperintensity or T1-hypointensity (representing neurodegeneration). The wider T1 enhancements associating with the decreased spontaneous neuronal activity in multiple resting-state networks in soman-exposed females than males suggest that neural changes unrelated to cellular atrophy impinge on brain function postexposure. Taken together with lower spontaneous neural activity in soman-exposed females, the results indicate some form of neuroprotective state that was not present in males. SIGNIFICANCE The results indicate that endpoints other than neurodegeneration may need to be considered to translate sex-based nerve agent effects in humans.
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Affiliation(s)
- Meghan Gage
- Department of Biomedical SciencesCollege of Veterinary Medicine, Iowa State UniversityAmesIowaUSA
| | - Suraj S Vasanthi
- Department of Biomedical SciencesCollege of Veterinary Medicine, Iowa State UniversityAmesIowaUSA
| | - Christina M Meyer
- Department of Biomedical SciencesCollege of Veterinary Medicine, Iowa State UniversityAmesIowaUSA
| | - Nikhil S Rao
- Department of Biomedical SciencesCollege of Veterinary Medicine, Iowa State UniversityAmesIowaUSA
| | - Daniel R Thedens
- Department of RadiologyCarver College of Medicine, The University of IowaIowa CityIowaUSA
| | - Sridhar S. Kannurpatti
- Department of Radiology, Rutgers Biomedical and Health SciencesNew Jersey Medical SchoolNewarkNew JerseyUSA
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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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Vavers E, Zvejniece L, Dambrova M. Sigma-1 receptor and seizures. Pharmacol Res 2023; 191:106771. [PMID: 37068533 PMCID: PMC10176040 DOI: 10.1016/j.phrs.2023.106771] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 04/03/2023] [Accepted: 04/13/2023] [Indexed: 04/19/2023]
Abstract
Over the last decade, sigma-1 receptor (Sig1R) has been recognized as a valid target for the treatment of seizure disorders and seizure-related comorbidities. Clinical trials with Sig1R ligands are underway testing therapies for the treatment of drug-resistant seizures, developmental and epileptic encephalopathies, and photosensitive epilepsy. However, the direct molecular mechanism by which Sig1R modulates seizures and the balance between excitatory and inhibitory pathways has not been fully elucidated. This review article aims to summarize existing knowledge of Sig1R and its involvement in seizures by focusing on the evidence obtained from Sig1R knockout animals and the anti-seizure effects of Sig1R ligands. In addition, this review article includes a discussion of the advantages and disadvantages of the use of existing compounds and describes the challenges and future perspectives on the use of Sig1R as a target for the treatment of seizure disorders.
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Affiliation(s)
- Edijs Vavers
- Latvian Institute of Organic Synthesis, Laboratory of Pharmaceutical Pharmacology, Aizkraukles 21, LV-1006, Riga, Latvia; University of Tartu, Faculty of Science and Technology, Institute of Chemistry, Ravila 14a, 50411, Tartu, Estonia.
| | - Liga Zvejniece
- Latvian Institute of Organic Synthesis, Laboratory of Pharmaceutical Pharmacology, Aizkraukles 21, LV-1006, Riga, Latvia
| | - Maija Dambrova
- Latvian Institute of Organic Synthesis, Laboratory of Pharmaceutical Pharmacology, Aizkraukles 21, LV-1006, Riga, Latvia; Riga Stradiņš University, Faculty of Pharmacy, Konsula 21, LV-1007, Riga, Latvia
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Gage M, Rao NS, Samidurai M, Putra M, Vasanthi SS, Meyer C, Wang C, Thippeswamy T. Soman (GD) Rat Model to Mimic Civilian Exposure to Nerve Agent: Mortality, Video-EEG Based Status Epilepticus Severity, Sex Differences, Spontaneously Recurring Seizures, and Brain Pathology. Front Cell Neurosci 2022; 15:798247. [PMID: 35197823 PMCID: PMC8859837 DOI: 10.3389/fncel.2021.798247] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 12/27/2021] [Indexed: 12/14/2022] Open
Abstract
Modeling a real-world scenario of organophosphate nerve agent (OPNA) exposure is challenging. Military personnel are premedicated with pyridostigmine, which led to the development of OPNA models with pyridostigmine/oxime pretreatment to investigate novel therapeutics for acute and chronic effects. However, civilians are not premedicated with pyridostigmine/oxime. Therefore, experimental models without pyridostigmine were developed by other laboratories though often only in males. Following OPNA exposure, prolonged convulsive seizures (CS) or status epilepticus (SE) are concerning. The duration and severity of CS/SE determine the extent of brain injury in survivors even after treating with medical countermeasures (MCM)/antidotes such as atropine, an oxime, and an anticonvulsant such as diazepam/midazolam. In this study, using a large mixed sex cohort of adult male and female rats, without pretreatment, we demonstrate severe SE lasting for >20 min in 82% of the animals in response to soman (GD,132 μg/kg, s.c.). Atropine sulfate (2 mg/kg, i.m.) and HI-6 (125 mg/kg, i.m.) were administered immediately following soman, and midazolam (3 mg/kg, i.m.) 1 h post-exposure. Immediate MCM treatment is impractical in civilian exposure to civilians, but this approach reduces mortality in experimental models. Interestingly, female rats, irrespective of estrous stages, had an average of 44 min CS (stage ≥ 3), while males had an average of 32 min CS during SE, starting from soman exposure to midazolam treatment. However, in telemetry device implanted groups, there were no significant sex differences in SE severity; males had 40 min and females 43 min of continuous CS until midazolam was administered. No animals died prior to midazolam administration and less than 5% died in the first week after soman intoxication. In telemetered animals, there was a direct correlation between EEG changes and behavioral seizures in real-time. In the long-term, convulsive spontaneously recurring seizures (SRS) were observed in 85% of randomly chosen animals. At 4-months post-soman, the brain histology confirmed reactive gliosis and neurodegeneration. The novel findings of this study are that, in non-telemetered animals, the SE severity following soman intoxication was significantly greater in females compared to males and that the estrous cycle did not influence the response.
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Affiliation(s)
- Meghan Gage
- Neuroscience Interdepartmental Program, Iowa State University, Ames, IA, United States.,Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Nikhil S Rao
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Manikandan Samidurai
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Marson Putra
- Neuroscience Interdepartmental Program, Iowa State University, Ames, IA, United States.,Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Suraj S Vasanthi
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Christina Meyer
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Chong Wang
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Thimmasettappa Thippeswamy
- Neuroscience Interdepartmental Program, Iowa State University, Ames, IA, United States.,Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
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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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Lumley L, Du F, Marrero-Rosado B, Stone M, Keith ZM, Schultz C, Whitten K, Walker K, Acon-Chen C, Wright L, Shih TM. Soman-induced toxicity, cholinesterase inhibition and neuropathology in adult male Göttingen minipigs. Toxicol Rep 2021; 8:896-907. [PMID: 33996503 PMCID: PMC8095108 DOI: 10.1016/j.toxrep.2021.04.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 04/09/2021] [Accepted: 04/16/2021] [Indexed: 01/05/2023] Open
Abstract
Animal models are essential for evaluating the toxicity of chemical warfare nerve agents (CWNAs) to extrapolate to human risk and are necessary to evaluate the efficacy of medical countermeasures. The Göttingen minipig is increasingly used for toxicological studies because it has anatomical and physiological characteristics that are similar to those of humans. Our objective was to determine whether the minipig would be a useful large animal model to evaluate the toxic effects of soman (GD). We determined the intramuscular (IM) median lethal dose (LD50) of GD in adult male Göttingen minipigs using an up-and-down dosing method. In addition to lethality estimates, we characterized the observable signs of toxicity, blood and tissue cholinesterase (ChE) activity and brain pathology following GD exposure. The 24 h LD50 of GD was estimated to be 4.7 μg/kg, with 95 % confidence limits of 3.6 and 6.3 μg/kg. As anticipated, GD inhibited ChE activity in blood and several tissues. Neurohistopathological analysis showed neurodegeneration and neuroinflammation in survivors exposed to 4.7 μg/kg of GD, including in the primary visual cortex and various thalamic nuclei. These findings suggest that the minipig will be a useful large animal model for assessing drugs to mitigate neuropathological effects of exposure to CWNAs.
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Affiliation(s)
- Lucille Lumley
- U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, United States
| | - Fu Du
- FD NeuroTechnologies, Inc., Columbia, MD, United States
| | - Brenda Marrero-Rosado
- U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, United States
| | - Michael Stone
- U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, United States
| | - Zora-Maya Keith
- U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, United States
| | - Caroline Schultz
- U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, United States
| | - Kimberly Whitten
- U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, United States
| | - Katie Walker
- U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, United States
| | - Cindy Acon-Chen
- U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, United States
| | - Linnzi Wright
- U.S. Army Combat Capabilities Development Command Chemical Biological Center, Aberdeen Proving Ground, MD, United States
| | - Tsung-Ming Shih
- U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, United States
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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: 21] [Impact Index Per Article: 7.0] [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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10
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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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11
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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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12
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Katyal P, Chu S, Montclare JK. Enhancing organophosphate hydrolase efficacy via protein engineering and immobilization strategies. Ann N Y Acad Sci 2020; 1480:54-72. [PMID: 32814367 DOI: 10.1111/nyas.14451] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 06/21/2020] [Accepted: 07/07/2020] [Indexed: 01/30/2023]
Abstract
Organophosphorus compounds (OPs), developed as pesticides and chemical warfare agents, are extremely toxic chemicals that pose a public health risk. Of the different detoxification strategies, organophosphate-hydrolyzing enzymes have attracted much attention, providing a potential route for detoxifying those exposed to OPs. Phosphotriesterase (PTE), also known as organophosphate hydrolase (OPH), is one such enzyme that has been extensively studied as a catalytic bioscavenger. In this review, we will discuss the protein engineering of PTE aimed toward improving the activity and stability of the enzyme. In order to make enzyme utilization in OP detoxification more favorable, enzyme immobilization provides an effective means to increase enzyme activity and stability. Here, we present several such strategies that enhance the storage and operational stability of PTE/OPH.
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Affiliation(s)
- Priya Katyal
- Department of Chemical and Biomolecular Engineering, New York University, Tandon School of Engineering, Brooklyn, New York
| | - Stanley Chu
- Department of Chemical and Biomolecular Engineering, New York University, Tandon School of Engineering, Brooklyn, New York
| | - Jin Kim Montclare
- Department of Chemical and Biomolecular Engineering, New York University, Tandon School of Engineering, Brooklyn, New York.,Department of Radiology, New York University Langone Health, New York, New York.,Department of Biomaterials, New York University College of Dentistry, New York, New York.,Department of Chemistry, New York University, New York, New York
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13
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Kundrick E, Marrero-Rosado B, Stone M, Schultz C, Walker K, Lee-Stubbs RB, de Araujo Furtado M, Lumley LA. Delayed midazolam dose effects against soman in male and female plasma carboxylesterase knockout mice. Ann N Y Acad Sci 2020; 1479:94-107. [PMID: 32027397 DOI: 10.1111/nyas.14311] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 01/13/2020] [Accepted: 01/19/2020] [Indexed: 01/30/2023]
Abstract
Chemical warfare nerve agent exposure leads to status epilepticus that may progress to epileptogenesis and severe brain pathology when benzodiazepine treatment is delayed. We evaluated the dose-response effects of delayed midazolam (MDZ) on toxicity induced by soman (GD) in the plasma carboxylesterase knockout (Es1-/- ) mouse, which, similar to humans, lacks plasma carboxylesterase. Initially, we compared the median lethal dose (LD50 ) of GD exposure in female Es1-/- mice across estrous with male mice and observed a greater LD50 during estrus compared with proestrus or with males. Subsequently, male and female GD-exposed Es1-/- mice treated with a dose range of MDZ 40 min after seizure onset were evaluated for survivability, seizure activity, and epileptogenesis. GD-induced neuronal loss and microglial activation were evaluated 2 weeks after exposure. Similar to our previous observations in rats, delayed treatment with MDZ dose-dependently increased survival and reduced seizure severity in GD-exposed mice, but was unable to prevent epileptogenesis, neuronal loss, or gliosis. These results suggest that MDZ is beneficial against GD exposure, even when treatment is delayed, but that adjunct therapies to enhance protection need to be identified. The Es1-/- mouse GD exposure model may be useful to screen for improved medical countermeasures against nerve agent exposure.
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Affiliation(s)
- Erica Kundrick
- US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland
| | - Brenda Marrero-Rosado
- US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland
| | - Michael Stone
- US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland
| | - Caroline Schultz
- US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland
| | - Katie Walker
- US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland
| | - Robyn B Lee-Stubbs
- US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland
| | | | - Lucille A Lumley
- US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland
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14
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Lumley L, Miller D, Muse WT, Marrero‐Rosado B, de Araujo Furtado M, Stone M, McGuire J, Whalley C. Neurosteroid and benzodiazepine combination therapy reduces status epilepticus and long-term effects of whole-body sarin exposure in rats. Epilepsia Open 2019; 4:382-396. [PMID: 31440720 PMCID: PMC6698686 DOI: 10.1002/epi4.12344] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 04/26/2019] [Accepted: 05/19/2019] [Indexed: 01/04/2023] Open
Abstract
OBJECTIVE Our objective was to evaluate the protective efficacy of the neurosteroid pregnanolone (3α-hydroxy-5β pregnan-20-one), a GABAA receptor-positive allosteric modulator, as an adjunct to benzodiazepine therapy against the chemical warfare nerve agent (CWNA) sarin (GB), using whole-body exposure, an operationally relevant route of exposure to volatile GB. METHODS Rats implanted with telemetry transmitters for the continuous measurement of cortical electroencephalographic (EEG) activity were exposed for 60 minutes to 3.0 LCt50 of GB via whole-body exposure. At the onset of toxic signs, rats were administered an intramuscular injection of atropine sulfate (2 mg/kg) and the oxime HI-6 (93.6 mg/kg) to increase survival rate and, 30 minutes after seizure onset, treated subcutaneously with diazepam (10 mg/kg) and intravenously with pregnanolone (4 mg/kg) or vehicle. Animals were evaluated for GB-induced status epilepticus (SE), spontaneous recurrent seizures (SRS), impairment in spatial memory acquisition, and brain pathology, and treatment groups were compared. RESULTS Delayed dual therapy with pregnanolone and diazepam reduced time in SE in GB-exposed rats compared to those treated with delayed diazepam monotherapy. The combination therapy of pregnanolone with diazepam also prevented impairment in the Morris water maze and reduced the neuronal loss and neuronal degeneration, evaluated at one and three months after exposure. SIGNIFICANCE Neurosteroid administration as an adjunct to benzodiazepine therapy offers an effective means to treat benzodiazepine-refractory SE, such as occurs following delayed treatment of GB exposure. This study is the first to present data on the efficacy of delayed pregnanolone and diazepam dual therapy in reducing seizure activity, performance deficits and brain pathology following an operationally relevant route of exposure to GB and supports the use of a neurosteroid as an adjunct to standard anticonvulsant therapy for the treatment of CWNA-induced SE.
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Affiliation(s)
- Lucille Lumley
- US Army Medical Research Institute of Chemical DefenseAberdeen Proving GroundMaryland
| | - Dennis Miller
- US Army Combat Capabilities Development Command Chemical Biological CenterAberdeen Proving GroundMaryland
| | - William T. Muse
- US Army Combat Capabilities Development Command Chemical Biological CenterAberdeen Proving GroundMaryland
| | - Brenda Marrero‐Rosado
- US Army Medical Research Institute of Chemical DefenseAberdeen Proving GroundMaryland
| | | | - Michael Stone
- US Army Medical Research Institute of Chemical DefenseAberdeen Proving GroundMaryland
| | - Jeffrey McGuire
- US Army Combat Capabilities Development Command Chemical Biological CenterAberdeen Proving GroundMaryland
| | - Christopher Whalley
- US Army Combat Capabilities Development Command Chemical Biological CenterAberdeen Proving GroundMaryland
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15
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Marrero-Rosado B, Rossetti F, Rice MW, Moffett MC, Lee RB, Stone MF, Lumley LA. Age-Related Susceptibility to Epileptogenesis and Neuronal Loss in Male Fischer Rats Exposed to Soman and Treated With Medical Countermeasures. Toxicol Sci 2019; 164:142-152. [PMID: 29596688 DOI: 10.1093/toxsci/kfy065] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Elderly individuals compose a large percentage of the world population; however, few studies have addressed the efficacy of current medical countermeasures (MCMs) against the effects of chemical warfare nerve agent exposure in aged populations. We evaluated the efficacy of the anticonvulsant diazepam in an old adult rat model of soman (GD) poisoning and compared the toxic effects to those observed in young adult rats when anticonvulsant treatment is delayed. After determining their respective median lethal dose (LD50) of GD, we exposed young adult and old adult rats to an equitoxic 1.2 LD50 dose of GD followed by treatment with atropine sulfate and the oxime HI-6 at 1 min after exposure, and diazepam at 30 min after seizure onset. Old adult rats that presented with status epilepticus were more susceptible to developing spontaneous recurrent seizures (SRSs). Neuropathological analysis revealed that in rats of both age groups that developed SRS, there was a significant reduction in the density of mature neurons in the piriform cortex, thalamus, and amygdala, with more pronounced neuronal loss in the thalamus of old adult rats compared with young adult rats. Furthermore, old adult rats displayed a reduced density of cells expressing glutamic acid decarboxylase 67, a marker of GABAergic interneurons, in the basolateral amygdala and piriform cortex, and a reduction of astrocyte activation in the piriform cortex. Our observations demonstrate the reduced effectiveness of current MCM in an old adult animal model of GD exposure and strongly suggest the need for countermeasures that are more tailored to the vulnerabilities of an aging population.
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Affiliation(s)
- Brenda Marrero-Rosado
- US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland 21010
| | - Franco Rossetti
- Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910
| | - Matthew W Rice
- US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland 21010
| | - Mark C Moffett
- US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland 21010
| | - Robyn B Lee
- US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland 21010
| | - Michael F Stone
- US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland 21010
| | - Lucille A Lumley
- US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland 21010
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16
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Ríos C, Farfán-Briseño AC, Manjarrez-Marmolejo J, Franco-Pérez J, Méndez-Armenta M, Nava-Ruiz C, Caballero-Chacón S, Ruiz-Diaz A, Baron-Flores V, Díaz-Ruiz A. Efficacy of dapsone administered alone or in combination with diazepam to inhibit status epilepticus in rats. Brain Res 2019; 1708:181-187. [DOI: 10.1016/j.brainres.2018.12.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/13/2018] [Accepted: 12/12/2018] [Indexed: 12/15/2022]
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17
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Aroniadou-Anderjaska V, Figueiredo TH, Apland JP, Braga MF. Targeting the glutamatergic system to counteract organophosphate poisoning: A novel therapeutic strategy. Neurobiol Dis 2019; 133:104406. [PMID: 30798006 DOI: 10.1016/j.nbd.2019.02.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 01/23/2019] [Accepted: 02/20/2019] [Indexed: 12/15/2022] Open
Abstract
One of the devastating effects of acute exposure to organophosphates, like nerve agents, is the induction of severe and prolonged status epilepticus (SE), which can cause death, or brain damage if death is prevented. Seizures after exposure are initiated by muscarinic receptor hyperstimulation-after inhibition of acetylcholinesterase by the organophosphorus agent and subsequent elevation of acetylcholine-but they are reinforced and sustained by glutamatergic hyperexcitation, which is the primary cause of brain damage. Diazepam is the FDA-approved anticonvulsant for the treatment of nerve agent-induced SE, and its replacement by midazolam is currently under consideration. However, clinical data derived from the treatment of SE of any etiology, as well as studies on the control of nerve agent-induced SE in animal models, have indicated that diazepam and midazolam control seizures only temporarily, their antiseizure efficacy is reduced as the latency of treatment from the onset of SE increases, and their neuroprotective efficacy is limited or absent. Here, we review data on the discovery of a novel anticonvulsant and neuroprotectant, LY293558, an AMPA/GluK1 receptor antagonist. Treatment of soman-exposed immature, young-adult, and aged rats with LY293558, terminates SE with limited recurrence of seizures, significantly protects from brain damage, and prevents long-term behavioral deficits, even when LY293558 is administered 1 h post-exposure. More beneficial effects and complete neuroprotection is obtained when LY293558 administration is combined with caramiphen, which antagonizes NMDA receptors. Further efficacy studies may bring the LY293558 + caramiphen combination therapy on the pathway to approval for human use.
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Affiliation(s)
- Vassiliki Aroniadou-Anderjaska
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, United States of America; Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, United States of America.
| | - Taiza H Figueiredo
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, United States of America.
| | - James P Apland
- Neuroscience Program, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, United States of America.
| | - Maria F Braga
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, United States of America; Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, United States of America.
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18
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Full Protection Against Soman-Induced Seizures and Brain Damage by LY293558 and Caramiphen Combination Treatment in Adult Rats. Neurotox Res 2018; 34:511-524. [PMID: 29713995 DOI: 10.1007/s12640-018-9907-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 04/14/2018] [Accepted: 04/17/2018] [Indexed: 10/17/2022]
Abstract
Acute exposure to nerve agents induces status epilepticus (SE), which causes brain damage or death. LY293558, an antagonist of AMPA and GluK1 kainate receptors is a very effective anticonvulsant and neuroprotectant against soman; however, some neuronal damage is still present after treatment of soman-exposed rats with LY293558. Here, we have tested whether combining LY293558 with an NMDA receptor antagonist can eliminate the residual damage. For this purpose, we chose caramiphen (CRM), an antimuscarinic compound with NMDA receptor antagonistic properties. Adult male rats were exposed to 1.2 × LD50 soman, and at 20 min after soman exposure, were injected with atropine + HI-6, or atropine + HI-6 + LY293558 (15 mg/kg), or atropine + HI-6 + LY293558 + CRM (50 mg/kg). We found that (1) the LY293558 + CRM treatment terminated SE significantly faster than LY293558 alone; (2) after cessation of the initial SE, seizures did not return in the LY293558 + CRM-treated group, during 72 h of monitoring; (3) power spectrum analysis of continuous EEG recordings for 7 days post-exposure showed increased delta and decreased gamma power that lasted beyond 24 h post-exposure only in the rats who did not receive anticonvulsant treatment; (4) spontaneous recurrent seizures appeared on day 7 only in the group that did not receive anticonvulsant treatment; (5) significant neuroprotection was achieved by LY293558 administration, while the rats who received LY293558 + CRM displayed no neurodegeneration; (6) body weight loss and recovery in the LY293558 + CRM-treated rats did not differ from those in control rats who were not exposed to soman. The data show that treatment with LY293558 + CRM provides full antiseizure and neuroprotective efficacy against soman.
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Myhrer T, Mariussen E, Aas P. Development of neuropathology following soman poisoning and medical countermeasures. Neurotoxicology 2018; 65:144-165. [DOI: 10.1016/j.neuro.2018.02.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 02/12/2018] [Accepted: 02/14/2018] [Indexed: 01/12/2023]
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Althaus AL, McCarren HS, Alqazzaz A, Jackson C, McDonough JH, Smith CD, Hoffman E, Hammond RS, Robichaud AJ, Doherty JJ. The synthetic neuroactive steroid SGE-516 reduces status epilepticus and neuronal cell death in a rat model of soman intoxication. Epilepsy Behav 2017; 68:22-30. [PMID: 28109985 DOI: 10.1016/j.yebeh.2016.12.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 11/18/2016] [Accepted: 12/17/2016] [Indexed: 12/18/2022]
Abstract
Organophosphorus nerve agents (OPNAs) are irreversible inhibitors of acetylcholinesterase that pose a serious threat to public health because of their use as chemical weapons. Exposure to high doses of OPNAs can dramatically potentiate cholinergic synaptic activity and cause status epilepticus (SE). Current standard of care for OPNA exposure involves treatment with cholinergic antagonists, oxime cholinesterase reactivators, and benzodiazepines. However, data from pre-clinical models suggest that OPNA-induced SE rapidly becomes refractory to benzodiazepines. Neuroactive steroids (NAS), such as allopregnanolone, retain anticonvulsant activity in rodent models of benzodiazepine-resistant SE, perhaps because they modulate a broader variety of GABAA receptor subtypes. SGE-516 is a novel, next generation NAS and a potent and selective GABAA receptor positive allosteric modulator (PAM). The present study first established that SGE-516 reduced electrographic seizures in the rat lithium-pilocarpine model of pharmacoresistant SE. Then the anticonvulsant activity of SGE-516 was investigated in the soman-intoxication model of OPNA-induced SE. SGE-516 (5.6, 7.5, and 10mg/kg, IP) significantly reduced electrographic seizure activity compared to control when administered 20min after SE onset. When 10mg/kg SGE-516 was administered 40min after SE onset, seizure activity was still significantly reduced compared to control. In addition, all cohorts of rats treated with SGE-516 exhibited significantly reduced neuronal cell death as measured by FluoroJade B immunohistochemistry. These data suggest synthetic NASs that positively modulate both synaptic and extrasynaptic GABAA receptors may be candidates for further study in the treatment of OPNA-induced SE.
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Affiliation(s)
| | - Hilary S McCarren
- United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA
| | - Aymen Alqazzaz
- United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA
| | - Cecelia Jackson
- United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA
| | - John H McDonough
- United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA
| | - Carl D Smith
- United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA
| | - Ethan Hoffman
- Drug Discovery, Sage Therapeutics, Inc., Cambridge, MA, USA
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Chapman S, Yaakov G, Egoz I, Rabinovitz I, Raveh L, Kadar T, Gilat E, Grauer E. Sarin-induced brain damage in rats is attenuated by delayed administration of midazolam. Neurotoxicology 2015; 49:132-8. [PMID: 25976749 DOI: 10.1016/j.neuro.2015.05.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 04/28/2015] [Accepted: 05/02/2015] [Indexed: 01/27/2023]
Abstract
Sarin poisoned rats display a hyper-cholinergic activity including hypersalivation, tremors, seizures and death. Here we studied the time and dose effects of midazolam treatment following nerve agent exposure. Rats were exposed to sarin (1.2 LD50, 108 μg/kg, im), and treated 1 min later with TMB4 and atropine (TA 7.5 and 5 mg/kg, im, respectively). Midazolam was injected either at 1 min (1 mg/kg, im), or 1 h later (1 or 5 mg/kg i.m.). Cortical seizures were monitored by electrocorticogram (ECoG). At 5 weeks, rats were assessed in a water maze task, and then their brains were extracted for biochemical analysis and histological evaluation. Results revealed a time and dose dependent effects of midazolam treatment. Rats treated with TA only displayed acute signs of sarin intoxication, 29% died within 24h and the ECoG showed seizures for several hours. Animals that received midazolam within 1 min survived with only minor clinical signs but with no biochemical, behavioral, or histological sequel. Animals that lived to receive midazolam at 1h (87%) survived and the effects of the delayed administration were dose dependent. Midazolam 5 mg/kg significantly counteracted the acute signs of intoxication and the impaired behavioral performance, attenuated some of the inflammatory response with no effect on morphological damage. Midazolam 1mg/kg showed only a slight tendency to modulate the cognitive function. In addition, the delayed administration of both midazolam doses significantly attenuated ECoG compared to TA treatment only. These results suggest that following prolonged seizure, high dose midazolam is beneficial in counteracting adverse effects of sarin poisoning.
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Affiliation(s)
- Shira Chapman
- Department of Pharmacology, Israel Institute for Biological Research, Ness Ziona, Israel
| | - Guy Yaakov
- Department of Pharmacology, Israel Institute for Biological Research, Ness Ziona, Israel
| | - Inbal Egoz
- Department of Pharmacology, Israel Institute for Biological Research, Ness Ziona, Israel
| | - Ishai Rabinovitz
- Department of Pharmacology, Israel Institute for Biological Research, Ness Ziona, Israel
| | - Lily Raveh
- Department of Pharmacology, Israel Institute for Biological Research, Ness Ziona, Israel
| | - Tamar Kadar
- Department of Pharmacology, Israel Institute for Biological Research, Ness Ziona, Israel
| | - Eran Gilat
- Department of Pharmacology, Israel Institute for Biological Research, Ness Ziona, Israel
| | - Ettie Grauer
- Department of Pharmacology, Israel Institute for Biological Research, Ness Ziona, Israel.
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Caramiphen edisylate: an optimal antidote against organophosphate poisoning. Toxicology 2014; 325:115-24. [PMID: 25201353 DOI: 10.1016/j.tox.2014.09.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 08/21/2014] [Accepted: 09/04/2014] [Indexed: 11/30/2022]
Abstract
Potent cholinesterase inhibitors such as sarin, induce an array of harmful effects including hypersecretion, convulsions and ultimately death. Surviving subjects demonstrate damage in specific brain regions that lead to cognitive and neurological dysfunctions. An early accumulation of acetylcholine in the synaptic clefts was suggested as the trigger of a sequence of neurochemical events such as an excessive outpour of glutamate and activation of its receptors. Indeed, alterations in NMDA and AMPA central receptors' densities were detected in brains of poisoned animals. Attempts to improve the current cholinergic-based treatment by adding potent anticonvulsants or antiglutamatergic drugs produced unsatisfactory results. In light of recent events in Syria and the probability of various scenarios of military or terrorist attacks involving organophosphate (OP) nerve agent, research should focus on finding markedly improved countermeasures. Caramiphen, an antimuscarinic drug with antiglutamatergic and GABAergic facilitating properties, was evaluated in a wide range of animals and experimental protocols against OP poisoning. Its remarkable efficacy against OP exposure was established both in prophylactic and post-exposure therapies in both small and large animals. The present review will highlight the outstanding neuroprotective effect of caramiphen as the optimal candidate for the treatment of OP-exposed subjects.
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Caramiphen edisylate as adjunct to standard therapy attenuates soman-induced seizures and cognitive deficits in rats. Neurotoxicol Teratol 2014; 44:89-104. [DOI: 10.1016/j.ntt.2014.06.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 05/30/2014] [Accepted: 06/03/2014] [Indexed: 02/06/2023]
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Chen J, Pan H, Chen C, Wu W, Iskandar K, He J, Piermartiri T, Jacobowitz DM, Yu QS, McDonough JH, Greig NH, Marini AM. (-)-Phenserine attenuates soman-induced neuropathology. PLoS One 2014; 9:e99818. [PMID: 24955574 PMCID: PMC4067273 DOI: 10.1371/journal.pone.0099818] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 05/15/2014] [Indexed: 11/18/2022] Open
Abstract
Organophosphorus (OP) nerve agents are deadly chemical weapons that pose an alarming threat to military and civilian populations. The irreversible inhibition of the critical cholinergic degradative enzyme acetylcholinesterase (AChE) by OP nerve agents leads to cholinergic crisis. Resulting excessive synaptic acetylcholine levels leads to status epilepticus that, in turn, results in brain damage. Current countermeasures are only modestly effective in protecting against OP-induced brain damage, supporting interest for evaluation of new ones. (-)-Phenserine is a reversible AChE inhibitor possessing neuroprotective and amyloid precursor protein lowering actions that reached Phase III clinical trials for Alzheimer's Disease where it exhibited a wide safety margin. This compound preferentially enters the CNS and has potential to impede soman binding to the active site of AChE to, thereby, serve in a protective capacity. Herein, we demonstrate that (-)-phenserine protects neurons against soman-induced neuronal cell death in rats when administered either as a pretreatment or post-treatment paradigm, improves motoric movement in soman-exposed animals and reduces mortality when given as a pretreatment. Gene expression analysis, undertaken to elucidate mechanism, showed that (-)-phenserine pretreatment increased select neuroprotective genes and reversed a Homer1 expression elevation induced by soman exposure. These studies suggest that (-)-phenserine warrants further evaluation as an OP nerve agent protective strategy.
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Affiliation(s)
- Jun Chen
- Neurology Department, Uniformed Services University of Health Sciences, Bethesda, Maryland, United States of America
| | - Hongna Pan
- Neurology Department, Uniformed Services University of Health Sciences, Bethesda, Maryland, United States of America
| | - Cynthia Chen
- Neurology Department, Uniformed Services University of Health Sciences, Bethesda, Maryland, United States of America
| | - Wei Wu
- Neurology Department, Uniformed Services University of Health Sciences, Bethesda, Maryland, United States of America
| | - Kevin Iskandar
- Neurology Department, Uniformed Services University of Health Sciences, Bethesda, Maryland, United States of America
| | - Jeffrey He
- Neurology Department, Uniformed Services University of Health Sciences, Bethesda, Maryland, United States of America
| | - Tetsade Piermartiri
- Neurology Department, Uniformed Services University of Health Sciences, Bethesda, Maryland, United States of America
| | - David M. Jacobowitz
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Qian-Sheng Yu
- Drug Design & Development Section, Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - John H. McDonough
- Pharmacology Branch, Research Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland, United States of America
| | - Nigel H. Greig
- Drug Design & Development Section, Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Ann M. Marini
- Neurology Department, Uniformed Services University of Health Sciences, Bethesda, Maryland, United States of America
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Silva L, Garlet Q, Benovit S, Dolci G, Mallmann C, Bürger M, Baldisserotto B, Longhi S, Heinzmann B. Sedative and anesthetic activities of the essential oils of Hyptis mutabilis (Rich.) Briq. and their isolated components in silver catfish (Rhamdia quelen). Braz J Med Biol Res 2013; 46:771-9. [PMID: 24068193 PMCID: PMC3854430 DOI: 10.1590/1414-431x20133013] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Accepted: 07/01/2013] [Indexed: 01/28/2023] Open
Abstract
This study evaluated the sedative and anesthetic effects of the essential oils (EO) of Hyptis mutabilis (Rich.) Briq. and their isolated components on silver catfish (Rhamdia quelen). Quantitative chemical differences between the EOs obtained from leaves and inflorescences were verified, and a new chemotype rich in globulol was described. Although there were no significant differences in the time of induction for sedation and anesthesia between the EOs, only the leaf EO at 344 mg/L anesthetized all fish without side effects. Fractionation of the leaf EO was carried out by column chromatography. The isolated compounds [(+)-1-terpinen-4-ol and (-)-globulol] showed different activity from that detected for the leaf EO in proportional concentrations and similar sedation to a eugenol control at 10 mg/L. However, fish exposed to 1-terpinen-4-ol (3 and 10 mg/L) did not remain sedated for 30 min. Anesthesia was obtained with 83-190 mg/L globulol, but animals showed loss of mucus during induction and mortality at these concentrations. Synergism of the depressor effects was detected with the association of globulol and benzodiazepine (BDZ), compared with either drug alone. Fish exposed to BDZ or globulol+BDZ association showed faster recovery from anesthesia in water containing flumazenil, but the same did not occur with globulol. In conclusion, the use of globulol in aquaculture procedures should be considered only at sedative concentrations of 10 and 20 mg/L, and its mechanism of action seems not to involve the GABAA-BDZ system.
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Affiliation(s)
- L.L. Silva
- Programa de Pós-Graduação em Farmacologia, Universidade Federal
de Santa Maria, Santa Maria, RS, Brasil
| | - Q.I. Garlet
- Programa de Pós-Graduação em Farmacologia, Universidade Federal
de Santa Maria, Santa Maria, RS, Brasil
| | - S.C. Benovit
- Programa de Pós-Graduação em Farmacologia, Universidade Federal
de Santa Maria, Santa Maria, RS, Brasil
| | - G. Dolci
- Programa de Pós-Graduação em Farmacologia, Universidade Federal
de Santa Maria, Santa Maria, RS, Brasil
| | - C.A. Mallmann
- Departamento de Medicina Veterinária Preventiva, Universidade
Federal de Santa Maria, Santa Maria, RS, Brasil
| | - M.E. Bürger
- Programa de Pós-Graduação em Farmacologia, Universidade Federal
de Santa Maria, Santa Maria, RS, Brasil
- Departamento de Fisiologia e Farmacologia, Universidade Federal
de Santa Maria, Santa Maria, RS, Brasil
| | - B. Baldisserotto
- Programa de Pós-Graduação em Farmacologia, Universidade Federal
de Santa Maria, Santa Maria, RS, Brasil
- Departamento de Fisiologia e Farmacologia, Universidade Federal
de Santa Maria, Santa Maria, RS, Brasil
| | - S.J. Longhi
- Departamento de Ciências Florestais, Unversidade Federal de
Santa Maria, Santa Maria, RS, Brasil
| | - B.M. Heinzmann
- Programa de Pós-Graduação em Farmacologia, Universidade Federal
de Santa Maria, Santa Maria, RS, Brasil
- Departamento de Farmácia Industrial, Universidade Federal de
Santa Maria, Santa Maria, RS, Brasil
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de Araujo Furtado M, Rossetti F, Chanda S, Yourick D. Exposure to nerve agents: from status epilepticus to neuroinflammation, brain damage, neurogenesis and epilepsy. Neurotoxicology 2012; 33:1476-1490. [PMID: 23000013 DOI: 10.1016/j.neuro.2012.09.001] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2012] [Revised: 07/25/2012] [Accepted: 09/03/2012] [Indexed: 12/17/2022]
Abstract
Epilepsy is a common neurological disorder characterized by an initial injury due to stroke, traumatic brain injury, brain infection, or febrile seizures causing status epilepticus (SE). This phenomenon precedes recurrent (secondary) seizures, the latent period (period without seizures) and downstream appearance of spontaneous recurrent seizures (SRS). Epilepsy inducers include the organophosphorous (OP) compounds modified as chemical warfare nerve agents, such as soman. SE induced by soman is a result of cholinergic system hyperactivity caused by the irreversible inhibition of acetylcholinesterase, and the subsequent increase in the amount of the neurotransmitter acetylcholine at central and peripheral sites. SE leads to profound, permanent, complex and widespread brain damage and associated cognitive and behavioral deficits, accompanied by impaired neurogenesis. Several anticonvulsant and neuroprotective strategies have been studied in order to avoid the epileptogenesis which occurs after SE caused by soman exposure. In recent studies, we showed that SRS occur post-soman exposure and neuropathology can be reduced with diazepam (DZP) and valproic acid (VPA) when administered in combination treatment. These effects are accompanied by neurogenesis seen 15 days post-exposure in the hippocampal dentate gyrus (DG). This review discusses several findings about epilepsy induced by soman exposure such as behavioral changes, EEG anomalies, neuropathology, neuroinflammation, neurogenesis, possible circuitry changes and current strategies for treatment. The soman seizure model is an important model of temporal lobe epilepsy (TLE) and comparable in certain respects with well studied models in the literature such as pilocarpine and kainic acid. All these models together allow for a greater understanding of the different mechanisms of seizure induction, propagation and options for treatment. These studies are very necessary for current military and civilian treatment regimens, against OP nerve agent exposure, which fail to prevent SE resulting in severe neuropathology and epilepsy.
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Affiliation(s)
- Marcio de Araujo Furtado
- Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Franco Rossetti
- Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Soma Chanda
- Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Debra Yourick
- Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States.
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