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Epigenetics in epilepsy. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2023; 198:249-269. [DOI: 10.1016/bs.pmbts.2023.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
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de Curtis M, Rossetti AO, Verde DV, van Vliet EA, Ekdahl CT. Brain pathology in focal status epilepticus: evidence from experimental models. Neurosci Biobehav Rev 2021; 131:834-846. [PMID: 34517036 DOI: 10.1016/j.neubiorev.2021.09.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 09/02/2021] [Accepted: 09/05/2021] [Indexed: 12/01/2022]
Abstract
Status Epilepticus (SE) is often a neurological emergency characterized by abnormally sustained, longer than habitual seizures. The new ILAE classification reports that SE "…can have long-term consequences including neuronal death, neuronal injury…depending on the type and duration of seizures". While it is accepted that generalized convulsive SE exerts detrimental effects on the brain, it is not clear if other forms of SE, such as focal non-convulsive SE, leads to brain pathology and contributes to long-term deficits in patients. With the available clinical and experimental data, it is hard to discriminate the specific action of the underlying SE etiologies from that exerted by epileptiform activity. This information is highly relevant in the clinic for better treatment stratification, which may include both medical and surgical intervention for seizure control. Here we review experimental studies of focal SE, with an emphasis on focal non-convulsive SE. We present a repertoire of brain pathologies observed in the most commonly used animal models and attempt to establish a link between experimental findings and human condition(s). The extensive literature on focal SE animal models suggest that the current approaches have significant limitations in terms of translatability of the findings to the clinic. We highlight the need for a more stringent description of SE features and brain pathology in experimental studies in animal models, to improve the accuracy in predicting clinical translation.
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Affiliation(s)
- Marco de Curtis
- Epilepsy Unit, Fondazione IRCCS Istituto NeurologicoCarlo Besta, Milano, Italy.
| | - Andrea O Rossetti
- Department of Clinical Neuroscience, University Hospital (CHUV) and University of Lausanne, Lausanne, Switzerland
| | - Diogo Vila Verde
- Epilepsy Unit, Fondazione IRCCS Istituto NeurologicoCarlo Besta, Milano, Italy
| | - Erwin A van Vliet
- Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Science Park 904, P.O. Box 94246, 1090 GE, Amsterdam, the Netherlands; Amsterdam UMC, University of Amsterdam, Department of (Neuro)Pathology, Amsterdam Neuroscience, Meibergdreef 9, Amsterdam, the Netherlands
| | - Christine T Ekdahl
- Division of Clinical Neurophysiology, Lund University, Sweden; Lund Epilepsy Center, Dept Clinical Sciences, Lund University, Sweden
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Yu N, Lin XJ, Di Q. How to Find Candidate Drug-targets for Antiepileptogenic Therapy? Curr Neuropharmacol 2021; 18:624-635. [PMID: 31989901 PMCID: PMC7457424 DOI: 10.2174/1570159x18666200128124338] [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: 10/31/2019] [Revised: 12/10/2019] [Accepted: 01/27/2020] [Indexed: 11/22/2022] Open
Abstract
Although over 25 antiepileptic drugs (AEDs) have become currently available for clinical use, the incidence of epilepsy worldwide and the proportions of drug-resistant epilepsy among them are not significantly reduced during the past decades. Traditional screens for AEDs have been mainly focused on their anti-ictogenic roles, and their efficacies primarily depend on suppressing neuronal excitability or enhancing inhibitory neuronal activity, almost without the influence on the epileptogenesis or with inconsistent results from different studies. Epileptogenesis refers to the pathological process of a brain from its normal status to the alterations with the continuous prone of unprovoked spontaneous seizures after brain insults, such as stroke, traumatic brain injury, CNS infectious, and autoimmune disorders, and even some specific inherited conditions. Recently growing experimental and clinical studies have discovered the underlying mechanisms for epileptogenesis, which are multi-aspect and multistep. These findings provide us a number of interesting sites for antiepileptogenic drugs (AEGDs). AEGDs have been evidenced as significantly roles of postponing or completely blocking the development of epilepsy in experimental models. The present review will introduce potential novel candidate drug-targets for AEGDs based on the published studies.
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Affiliation(s)
- Nian Yu
- Department of Neurology, The Affiliated Nanjing Brain Hospital of Nanjing Medical University, 210029, Nanjing, China
| | - Xing-Jian Lin
- Department of Neurology, The Affiliated Nanjing Brain Hospital of Nanjing Medical University, 210029, Nanjing, China
| | - Qing Di
- Department of Neurology, The Affiliated Nanjing Brain Hospital of Nanjing Medical University, 210029, Nanjing, China
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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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Lunke S, Maxwell S, Khurana I, K N H, Okabe J, Al-Hasani K, El-Osta A. Epigenetic evidence of an Ac/Dc axis by VPA and SAHA. Clin Epigenetics 2021; 13:58. [PMID: 33743782 PMCID: PMC7981901 DOI: 10.1186/s13148-021-01050-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 03/08/2021] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Valproic acid (VPA) is one of the most commonly used anti-epileptic drugs with pharmacological actions on GABA and blocking voltage-gated ion channels. VPA also inhibits histone deacetylase (HDAC) activity. Suberoylanilide hydroxamic acid is also a member of a larger class of compounds that inhibit HDACs. At the time of this article, there are 123 active international clinical trials for VPA (also known as valproate, convulex, divalproex, and depakote) and SAHA (vorinostat, zolinza). While it is well known that VPA and SAHA influence the accumulation of acetylated lysine residues on histones, their true epigenetic complexity remains poorly understood. RESULTS Primary human cells were exposed to VPA and SAHA to understand the extent of histone acetylation (H3K9/14ac) using chromatin immunoprecipitation followed by sequencing (ChIP-seq). Because histone acetylation is often associated with modification of lysine methylation, we also examined H3K4me3 and H3K9me3. To assess the influence of the HDAC inhibitors on gene expression, we used RNA sequencing (RNA-seq). ChIP-seq reveals a distribution of histone modifications that is robust and more broadly regulated than previously anticipated by VPA and SAHA. Histone acetylation is a characteristic of the pharmacological inhibitors that influenced gene expression. Surprisingly, we observed histone deacetylation by VPA stimulation is a predominant signature following SAHA exposure and thus defines an acetylation/deacetylation (Ac/Dc) axis. ChIP-seq reveals regionalisation of histone acetylation by VPA and broader deacetylation by SAHA. Independent experiments confirm H3K9/14 deacetylation of NFκB target genes by SAHA. CONCLUSIONS The results provide an important framework for understanding the Ac/Dc axis by highlighting a broader complexity of histone modifications by the most established and efficacious anti-epileptic medication in this class, VPA and comparison with the broad spectrum HDAC inhibitor, SAHA.
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Affiliation(s)
- Sebastian Lunke
- Baker Heart and Diabetes Institute, Melbourne, VIC, 3004, Australia
| | - Scott Maxwell
- Baker Heart and Diabetes Institute, Melbourne, VIC, 3004, Australia.,Epigenetics in Human Health and Disease Laboratory, Central Clinical School, Monash University, Melbourne, VIC, 3004, Australia
| | - Ishant Khurana
- Baker Heart and Diabetes Institute, Melbourne, VIC, 3004, Australia.,Epigenetics in Human Health and Disease Laboratory, Central Clinical School, Monash University, Melbourne, VIC, 3004, Australia
| | - Harikrishnan K N
- Baker Heart and Diabetes Institute, Melbourne, VIC, 3004, Australia.,Epigenetics in Human Health and Disease Laboratory, Central Clinical School, Monash University, Melbourne, VIC, 3004, Australia.,Department of Clinical Pathology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Jun Okabe
- Baker Heart and Diabetes Institute, Melbourne, VIC, 3004, Australia.,Epigenetics in Human Health and Disease Laboratory, Central Clinical School, Monash University, Melbourne, VIC, 3004, Australia
| | - Keith Al-Hasani
- Baker Heart and Diabetes Institute, Melbourne, VIC, 3004, Australia.,Epigenetics in Human Health and Disease Laboratory, Central Clinical School, Monash University, Melbourne, VIC, 3004, Australia
| | - Assam El-Osta
- Baker Heart and Diabetes Institute, Melbourne, VIC, 3004, Australia. .,Epigenetics in Human Health and Disease Laboratory, Central Clinical School, Monash University, Melbourne, VIC, 3004, Australia. .,Department of Diabetes, Central Clinical School, Monash University, Melbourne, VIC, 3004, Australia. .,Department of Clinical Pathology, The University of Melbourne, Parkville, VIC, 3010, Australia. .,Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR. .,Hong Kong Institute of Diabetes and Obesity, Prince of Wales Hospital, The Chinese University of Hong Kong, 3/F Lui Che Woo Clinical Sciences Building, 30-32 Ngan Shing Street, Sha Tin, Hong Kong SAR. .,Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR. .,Biomedical Laboratory Science, Department of Technology, Faculty of Health, University College Copenhagen, Copenhagen, Denmark.
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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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Rusek M, Czuczwar SJ. A review of clinically significant drug-drug interactions involving angiotensin II receptor antagonists and antiepileptic drugs. Expert Opin Drug Metab Toxicol 2020; 16:507-515. [PMID: 32397766 DOI: 10.1080/17425255.2020.1763955] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
INTRODUCTION Angiotensin II receptor blockers are widely used for the treatment of arterial hypertension and heart failure. However, recent studies on animal models of seizures showed that in the brain, the renin-angiotensin-aldosterone system might be involved in neuroinflammation; therefore, the administration of angiotensin II receptor blockers that cross the blood/brain barrier, reduces not only blood pressure but reduces neuroinflammation-induced neuronal injury. Apart from this neuroprotective effect, these drugs exhibit anticonvulsant activity in animal models of seizures, and losartan is associated with a probable anti-epileptogenic activity. AREAS COVERED In this review, we intended to highlight the role of drug-drug interactions involving angiotensin II receptor antagonists with antiepileptic drugs accompanied by a brief characteristic of the role of RAS in neuroinflammation. EXPERT OPINION Some combinations of antiepileptic drugs (lamotrigine or valproate) with sartans are particularly effective in terms of enhanced seizure control. Considering a possible anti-epileptogenic activity of losartan, its combinations with antiepileptic drugs may prove especially beneficial in epileptogenesis inhibition.
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Affiliation(s)
- Marta Rusek
- Department of Pathophysiology, Medical University of Lublin , Lublin, Poland.,Department of Dermatology, Venereology and Pediatric Dermatology, Laboratory for Immunology of Skin Diseases, Medical University of Lublin , Lublin, Poland
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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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Marrero-Rosado B, de Araujo Furtado M, Schultz CR, Stone M, Kundrick E, Walker K, O'Brien S, Du F, Lumley LA. Soman-induced status epilepticus, epileptogenesis, and neuropathology in carboxylesterase knockout mice treated with midazolam. Epilepsia 2018; 59:2206-2218. [PMID: 30368799 PMCID: PMC6334636 DOI: 10.1111/epi.14582] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Revised: 09/21/2018] [Accepted: 09/24/2018] [Indexed: 12/31/2022]
Abstract
Objective Exposure to chemical warfare nerve agents (CWNAs), such as soman (GD), can induce status epilepticus (SE) that becomes refractory to benzodiazepines when treatment is delayed, leading to increased risk of epileptogenesis, severe neuropathology, and long‐term behavioral and cognitive deficits. Rodent models, widely used to evaluate novel medical countermeasures (MCMs) against CWNA exposure, normally express plasma carboxylesterase, an enzyme involved in the metabolism of certain organophosphorus compounds. To better predict the efficacy of novel MCMs against CWNA exposure in human casualties, it is crucial to use appropriate animal models that mirror the human condition. We present a comprehensive characterization of the seizurogenic, epileptogenic, and neuropathologic effects of GD exposure with delayed anticonvulsant treatment in the plasma carboxylesterase knockout (ES1−/−) mouse. Methods Electroencephalography (EEG) electrode‐implanted ES1−/− and wild‐type (C57BL/6) mice were exposed to various seizure‐inducing doses of GD, treated with atropine sulfate and the oxime HI‐6 at 1 minute after exposure, and administered midazolam at 15‐30 minutes following the onset of seizure activity. The latency of acute seizure onset and spontaneous recurrent seizures (SRS) was assessed, as were changes in EEG power spectra. At 2 weeks after GD exposure, neurodegeneration and neuroinflammation were assessed. Results GD‐exposed ES1−/− mice displayed a dose‐dependent response in seizure severity. Only ES1−/− mice exposed to the highest tested dose of GD developed SE, subchronic alterations in EEG power spectra, and SRS. Degree of neuronal cell loss and neuroinflammation were dose‐dependent; no significant neuropathology was observed in C57BL/6 mice or ES1−/− mice exposed to lower GD doses. Significance The US Food and Drug Administration (FDA) animal rule requires the use of relevant animal models for the advancement of MCMs against CWNAs. We present evidence that argues for the use of the ES1−/− mouse model to screen anticonvulsant, antiepileptic, and/or neuroprotective drugs against GD‐induced toxicity, as well as to identify mechanisms of GD‐induced epileptogenesis.
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Affiliation(s)
- Brenda Marrero-Rosado
- US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland
| | | | - Caroline R Schultz
- 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
| | - Erica Kundrick
- 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
| | - Sean O'Brien
- US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland
| | - Fu Du
- FD NeuroTechnologies, Columbia, Maryland
| | - Lucille A Lumley
- US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland
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Ibhazehiebo K, Gavrilovici C, de la Hoz CL, Ma SC, Rehak R, Kaushik G, Meza Santoscoy PL, Scott L, Nath N, Kim DY, Rho JM, Kurrasch DM. A novel metabolism-based phenotypic drug discovery platform in zebrafish uncovers HDACs 1 and 3 as a potential combined anti-seizure drug target. Brain 2018; 141:744-761. [PMID: 29373639 PMCID: PMC5837409 DOI: 10.1093/brain/awx364] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 10/29/2017] [Accepted: 11/05/2017] [Indexed: 01/01/2023] Open
Abstract
Despite the development of newer anti-seizure medications over the past 50 years, 30-40% of patients with epilepsy remain refractory to treatment. One explanation for this lack of progress is that the current screening process is largely biased towards transmembrane channels and receptors, and ignores intracellular proteins and enzymes that might serve as efficacious molecular targets. Here, we report the development of a novel drug screening platform that harnesses the power of zebrafish genetics and combines it with in vivo bioenergetics screening assays to uncover therapeutic agents that improve mitochondrial health in diseased animals. By screening commercially available chemical libraries of approved drugs, for which the molecular targets and pathways are well characterized, we were able to reverse-identify the proteins targeted by efficacious compounds and confirm the physiological roles that they play by utilizing other pharmacological ligands. Indeed, using an 870-compound screen in kcna1-morpholino epileptic zebrafish larvae, we uncovered vorinostat (Zolinza™; suberanilohydroxamic acid, SAHA) as a potent anti-seizure agent. We further demonstrated that vorinostat decreased average daily seizures by ∼60% in epileptic Kcna1-null mice using video-EEG recordings. Given that vorinostat is a broad histone deacetylase (HDAC) inhibitor, we then delineated a specific subset of HDACs, namely HDACs 1 and 3, as potential drug targets for future screening. In summary, we have developed a novel phenotypic, metabolism-based experimental therapeutics platform that can be used to identify new molecular targets for future drug discovery in epilepsy.
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Affiliation(s)
- Kingsley Ibhazehiebo
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, Canada
- Alberta Children’s Hospital Research Institute, University of Calgary, Canada
| | - Cezar Gavrilovici
- Alberta Children’s Hospital Research Institute, University of Calgary, Canada
- Departments of Pediatrics, Clinical Neurosciences, Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Cristiane L de la Hoz
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, Canada
- Alberta Children’s Hospital Research Institute, University of Calgary, Canada
| | - Shun-Chieh Ma
- Departments of Neurology and Neurobiology, Barrow Neurological Institute, St Joseph’s Hospital and Medical Center, Phoenix, Arizona, USA
| | - Renata Rehak
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, Canada
- Alberta Children’s Hospital Research Institute, University of Calgary, Canada
| | - Gaurav Kaushik
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, Canada
- Alberta Children’s Hospital Research Institute, University of Calgary, Canada
| | - Paola L Meza Santoscoy
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, Canada
- Alberta Children’s Hospital Research Institute, University of Calgary, Canada
| | - Lucas Scott
- Alberta Children’s Hospital Research Institute, University of Calgary, Canada
- Departments of Pediatrics, Clinical Neurosciences, Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Nandan Nath
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, Canada
- Alberta Children’s Hospital Research Institute, University of Calgary, Canada
| | - Do-Young Kim
- Departments of Neurology and Neurobiology, Barrow Neurological Institute, St Joseph’s Hospital and Medical Center, Phoenix, Arizona, USA
| | - Jong M Rho
- Alberta Children’s Hospital Research Institute, University of Calgary, Canada
- Departments of Pediatrics, Clinical Neurosciences, Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Deborah M Kurrasch
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, Canada
- Alberta Children’s Hospital Research Institute, University of Calgary, Canada
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Assessment of brain oxygenation imbalance following soman exposure in rats. Neurotoxicology 2018; 65:28-37. [PMID: 29378300 DOI: 10.1016/j.neuro.2018.01.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 01/18/2018] [Accepted: 01/19/2018] [Indexed: 10/18/2022]
Abstract
Nerve agents (NAs) are potent organophosphorus (OP) compounds with applications in chemical warfare. OP compounds act by inhibiting acetylcholinesterase (AChE). Soman (O-pinacolyl methylphosphonofluoridate) is one of the most potent NAs. It is well known that small doses of NAs can be lethal, and that even non-lethal exposure leads to long-term mental debilitation/neurological damage. However, the neuropathology following exposure to sub-lethal nerve agents is not well understood. In this study, we examined changes in tissue oxygenation (pO2) in the cortex and hippocampus after a sub-lethal dose of soman [80-90 μg/kg; subcutaneous]. pO2 changes can provide information regarding oxygen delivery and utilization and may be indicative of a disruption in cerebral blood flow and/or metabolism. Changes in oxygenation were measured with chronically implanted oxygen sensors in awake and freely moving rats. Measurements were taken before, during, and after soman-induced convulsive seizures. Soman exposure resulted in an immediate increase in pO2 in the cortex, followed by an even greater increase that precedes the onset of soman-induced convulsive seizures. The rise in hippocampus pO2 was delayed relative to the cortex, although the general pattern of brain oxygenation between these two regions was similar. After convulsive seizures began, pO2 levels declined but usually remained hyperoxygenated. Following the decline in pO2, low frequency cycles of large amplitude changes were observed in both the cortex and hippocampus. This pattern is consistent with recurring seizures. Measuring real-time changes in brain pO2 provides new information on the physiological status of the brain following soman exposure. These results highlight that the measurement of brain oxygenation could provide a sensitive marker of nerve agent exposure and serve as a biomarker for treatment studies.
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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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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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Miller SL, Aroniadou-Anderjaska V, Pidoplichko VI, Figueiredo TH, Apland JP, Krishnan JKS, Braga MFM. The M1 Muscarinic Receptor Antagonist VU0255035 Delays the Development of Status Epilepticus after Organophosphate Exposure and Prevents Hyperexcitability in the Basolateral Amygdala. J Pharmacol Exp Ther 2016; 360:23-32. [PMID: 27799295 DOI: 10.1124/jpet.116.236125] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 10/27/2016] [Indexed: 12/31/2022] Open
Abstract
Exposure to organophosphorus toxins induces seizures that progress to status epilepticus (SE), which can cause brain damage or death. Seizures are generated by hyperstimulation of muscarinic receptors, subsequent to inhibition of acetylcholinesterase; this is followed by glutamatergic hyperactivity, which sustains and reinforces seizure activity. It has been unclear which muscarinic receptor subtypes are involved in seizure initiation and the development of SE in the early phases after exposure. Here, we show that pretreatment of rats with the selective M1 receptor antagonist, VU0255035 [N-(3-oxo-3-(4-(pyridine-4-yl)piperazin-1-yl)propyl)-benzo[c][1,2,5]thiadiazole-4 sulfonamide], significantly suppressed seizure severity and prevented the development of SE for about 40 minutes after exposure to paraoxon or soman, suggesting an important role of the M1 receptor in the early phases of seizure generation. In addition, in in vitro brain slices of the basolateral amygdala (a brain region that plays a key role in seizure initiation after nerve agent exposure), VU0255035 blocked the effects produced by bath application of paraoxon-namely, a brief barrage of spontaneous inhibitory postsynaptic currents, followed by a significant increase in the ratio of the total charge transferred by spontaneous excitatory postsynaptic currents over that of the inhibitory postsynaptic currents. Furthermore, paraoxon enhanced the hyperpolarization-activated cation current Ih in basolateral amygdala principal cells, which could be one of the mechanisms underlying the increased glutamatergic activity, an effect that was also blocked in the presence of VU0255035. Thus, selective M1 antagonists may be an efficacious pretreatment in contexts in which there is risk for exposure to organophosphates, as these antagonists will delay the development of SE long enough for medical assistance to arrive.
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Affiliation(s)
- Steven L Miller
- Departments of Anatomy, Physiology, and Genetics (S.L.M., V.A.-A., V.I.P., T.H.F., J.K.S.K., M.F.M.B.) and Psychiatry (V.A.-A., M.F.M.B.), and Program in Neuroscience (S.L.M., V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland; and Neurotoxicology Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.)
| | - Vassiliki Aroniadou-Anderjaska
- Departments of Anatomy, Physiology, and Genetics (S.L.M., V.A.-A., V.I.P., T.H.F., J.K.S.K., M.F.M.B.) and Psychiatry (V.A.-A., M.F.M.B.), and Program in Neuroscience (S.L.M., V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland; and Neurotoxicology Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.)
| | - Volodymyr I Pidoplichko
- Departments of Anatomy, Physiology, and Genetics (S.L.M., V.A.-A., V.I.P., T.H.F., J.K.S.K., M.F.M.B.) and Psychiatry (V.A.-A., M.F.M.B.), and Program in Neuroscience (S.L.M., V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland; and Neurotoxicology Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.)
| | - Taiza H Figueiredo
- Departments of Anatomy, Physiology, and Genetics (S.L.M., V.A.-A., V.I.P., T.H.F., J.K.S.K., M.F.M.B.) and Psychiatry (V.A.-A., M.F.M.B.), and Program in Neuroscience (S.L.M., V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland; and Neurotoxicology Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.)
| | - James P Apland
- Departments of Anatomy, Physiology, and Genetics (S.L.M., V.A.-A., V.I.P., T.H.F., J.K.S.K., M.F.M.B.) and Psychiatry (V.A.-A., M.F.M.B.), and Program in Neuroscience (S.L.M., V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland; and Neurotoxicology Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.)
| | - Jishnu K S Krishnan
- Departments of Anatomy, Physiology, and Genetics (S.L.M., V.A.-A., V.I.P., T.H.F., J.K.S.K., M.F.M.B.) and Psychiatry (V.A.-A., M.F.M.B.), and Program in Neuroscience (S.L.M., V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland; and Neurotoxicology Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.)
| | - Maria F M Braga
- Departments of Anatomy, Physiology, and Genetics (S.L.M., V.A.-A., V.I.P., T.H.F., J.K.S.K., M.F.M.B.) and Psychiatry (V.A.-A., M.F.M.B.), and Program in Neuroscience (S.L.M., V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland; and Neurotoxicology Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.)
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15
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Yao ZG, Jing HY, Wang DM, Lv BB, Li JM, Liu FF, Fan H, Sun XC, Qin YJ, Zhao MQ. Valproic acid ameliorates olfactory dysfunction in APP/PS1 transgenic mice of Alzheimer's disease: Ameliorations from the olfactory epithelium to the olfactory bulb. Pharmacol Biochem Behav 2016; 144:53-9. [PMID: 26948859 DOI: 10.1016/j.pbb.2016.02.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 02/25/2016] [Accepted: 02/29/2016] [Indexed: 11/29/2022]
Abstract
Olfactory dysfunction is a common and early symptom of many neurodegenerative diseases, particularly of Alzheimer's disease (AD) and mild cognitive impairment, pointing to the progression to dementia. Recent studies have revealed that valproic acid (VPA) has neuroprotective effects in rodent models of AD. In this study, we investigated the effects of VPA on olfactory dysfunction of APP/PS1 double transgenic mouse models of AD. After continuous treatment with a 100mg/kg daily dose of VPA for 3 months, APP/PS1 mice showed improved olfactory performances. In agreement with the behavioral findings, VPA treatment reduced amyloid β (Aβ) burden in the olfactory epithelium (OE) of transgenic mice. And, VPA increased epithelial thickness of the olfactory mucosa through decreased cell apoptosis and increased cell proliferation. In the olfactory bulb (OB), VPA administration also reduced senile plaques and levels of soluble and insoluble Aβ42 peptides. Besides, VPA promoted the increase of mitral cells and decrease of neurofilament immunostaining. In hence, VPA treatment completely improved the olfactory performances and prevented degenerative changes of the OE and OB. Our study raises the possibility of AD diagnosis by OE biopsy. Moreover, VPA may provide a novel therapeutic strategy for the treatment of olfactory dysfunction in AD patients.
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Affiliation(s)
- Zhi-Gang Yao
- Department of Pathology, Shandong Provincial Hospital Affiliated to Shandong University, No. 324 Jingwu Road, Jinan 250021, China
| | - Hai-Yan Jing
- Department of Pathology, Shandong Provincial Hospital Affiliated to Shandong University, No. 324 Jingwu Road, Jinan 250021, China
| | - Dong-Mei Wang
- Department of Pathogen Biology, Medical College, Henan University of Science and Technology, Building 6, Anhui Jianxi District, Luoyang 471003, China
| | - Bei-Bei Lv
- Department of Pathology, Shandong Provincial Hospital Affiliated to Shandong University, No. 324 Jingwu Road, Jinan 250021, China
| | - Jia-Mei Li
- Department of Pathology, Shandong Provincial Hospital Affiliated to Shandong University, No. 324 Jingwu Road, Jinan 250021, China
| | - Feng-Feng Liu
- Department of Pathology, Shandong Provincial Hospital Affiliated to Shandong University, No. 324 Jingwu Road, Jinan 250021, China
| | - Hui Fan
- Department of Pathology, Shandong Provincial Hospital Affiliated to Shandong University, No. 324 Jingwu Road, Jinan 250021, China
| | - Xi-Chao Sun
- Department of Pathology, Shandong Provincial Hospital Affiliated to Shandong University, No. 324 Jingwu Road, Jinan 250021, China
| | - Ye-Jun Qin
- Department of Pathology, Shandong Provincial Hospital Affiliated to Shandong University, No. 324 Jingwu Road, Jinan 250021, China
| | - Miao-Qing Zhao
- Department of Pathology, Shandong Provincial Hospital Affiliated to Shandong University, No. 324 Jingwu Road, Jinan 250021, China
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16
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Piermartiri T, Pan H, Figueiredo TH, Marini AM. α-Linolenic Acid, A Nutraceutical with Pleiotropic Properties That Targets Endogenous Neuroprotective Pathways to Protect against Organophosphate Nerve Agent-Induced Neuropathology. Molecules 2015; 20:20355-80. [PMID: 26569216 PMCID: PMC6332275 DOI: 10.3390/molecules201119698] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Revised: 10/29/2015] [Accepted: 11/03/2015] [Indexed: 01/23/2023] Open
Abstract
α-Linolenic acid (ALA) is a nutraceutical found in vegetable products such as flax and walnuts. The pleiotropic properties of ALA target endogenous neuroprotective and neurorestorative pathways in brain and involve the transcription factor nuclear factor kappa B (NF-κB), brain-derived neurotrophic factor (BDNF), a major neuroprotective protein in brain, and downstream signaling pathways likely mediated via activation of TrkB, the cognate receptor of BDNF. In this review, we discuss possible mechanisms of ALA efficacy against the highly toxic OP nerve agent soman. Organophosphate (OP) nerve agents are highly toxic chemical warfare agents and a threat to military and civilian populations. Once considered only for battlefield use, these agents are now used by terrorists to inflict mass casualties. OP nerve agents inhibit the critical enzyme acetylcholinesterase (AChE) that rapidly leads to a cholinergic crisis involving multiple organs. Status epilepticus results from the excessive accumulation of synaptic acetylcholine which in turn leads to the overactivation of muscarinic receptors; prolonged seizures cause the neuropathology and long-term consequences in survivors. Current countermeasures mitigate symptoms and signs as well as reduce brain damage, but must be given within minutes after exposure to OP nerve agents supporting interest in newer and more effective therapies. The pleiotropic properties of ALA result in a coordinated molecular and cellular program to restore neuronal networks and improve cognitive function in soman-exposed animals. Collectively, ALA should be brought to the clinic to treat the long-term consequences of nerve agents in survivors. ALA may be an effective therapy for other acute and chronic neurodegenerative disorders.
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Affiliation(s)
- Tetsade Piermartiri
- Molecular and Cellular Biology Graduate School Program, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
| | - Hongna Pan
- Department of Neurology and Program in Neuroscience, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
| | - Taiza H Figueiredo
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
| | - Ann M Marini
- Department of Neurology and Program in Neuroscience, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
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Abstract
Epigenetic processes in the brain involve the transfer of information arising from short-lived cellular signals and changes in neuronal activity into lasting effects on gene expression. Key molecular mediators of epigenetics include methylation of DNA, histone modifications, and noncoding RNAs. Emerging findings in animal models and human brain tissue reveal that epilepsy and epileptogenesis are associated with changes to each of these contributors to the epigenome. Understanding and influencing the molecular mechanisms controlling epigenetic change could open new avenues for treatment. DNA methylation, particularly hypermethylation, has been found to increase within gene body regions and interference with DNA methylation in epilepsy can change gene expression profiles and influence epileptogenesis. Posttranscriptional modification of histones, including transient as well as sustained changes to phosphorylation and acetylation, have been reported, which appear to influence gene expression. Finally, roles have emerged for noncoding RNAs in brain excitability and seizure thresholds, including microRNA and long noncoding RNA. Together, research supports strong effects of epigenetics influencing gene expression in epilepsy, suggesting future therapeutic approaches to manipulate epigenetic processes to treat or prevent epilepsy.
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Affiliation(s)
- David C Henshall
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin 2, Ireland
| | - Katja Kobow
- Department of Neuropathology, University Hospital Erlangen, 91054 Erlangen, Germany
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18
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Pan H, Piermartiri TCB, Chen J, McDonough J, Oppel C, Driwech W, Winter K, McFarland E, Black K, Figueiredo T, Grunberg N, Marini AM. Repeated systemic administration of the nutraceutical alpha-linolenic acid exerts neuroprotective efficacy, an antidepressant effect and improves cognitive performance when given after soman exposure. Neurotoxicology 2015; 51:38-50. [PMID: 26386148 DOI: 10.1016/j.neuro.2015.09.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 09/04/2015] [Accepted: 09/14/2015] [Indexed: 10/23/2022]
Abstract
Exposure to nerve agents results in severe seizures or status epilepticus caused by the inhibition of acetylcholinesterase, a critical enzyme that breaks down acetylcholine to terminate neurotransmission. Prolonged seizures cause brain damage and can lead to long-term consequences. Current countermeasures are only modestly effective against the brain damage supporting interest in the evaluation of new and efficacious therapies. The nutraceutical alpha-linolenic acid (LIN) is an essential omega-3 polyunsaturated fatty acid that has a wide safety margin. Previous work showed that a single intravenous injection of alpha-linolenic acid (500 nmol/kg) administered before or after soman significantly protected against soman-induced brain damage when analyzed 24h after exposure. Here, we show that administration of three intravenous injections of alpha-linolenic acid over a 7 day period after soman significantly improved motor performance on the rotarod, enhanced memory retention, exerted an anti-depressant-like activity and increased animal survival. This dosing schedule significantly reduced soman-induced neuronal degeneration in four major vulnerable brain regions up to 21 days. Taken together, alpha-linolenic acid reduces the profound behavioral deficits induced by soman possibly by decreasing neuronal cell death, and increases animal survival.
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Affiliation(s)
- Hongna Pan
- Department of Neurology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Tetsade C B Piermartiri
- Molecular and Cellular Biology Graduate School Program, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Jun Chen
- Department of Neurology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - John McDonough
- Department of Medical and Clinical Psychology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Craig Oppel
- Department of Medical and Clinical Psychology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Wafae Driwech
- Pharmacology Branch, Research Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, United States
| | - Kristin Winter
- Pharmacology Branch, Research Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, United States
| | - Emylee McFarland
- Pharmacology Branch, Research Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, United States
| | - Katelyn Black
- Pharmacology Branch, Research Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, United States
| | - Taiza Figueiredo
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Neil Grunberg
- Department of Medical and Clinical Psychology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Ann M Marini
- Department of Neurology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States.
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Puttachary S, Sharma S, Stark S, Thippeswamy T. Seizure-induced oxidative stress in temporal lobe epilepsy. BIOMED RESEARCH INTERNATIONAL 2015; 2015:745613. [PMID: 25650148 PMCID: PMC4306378 DOI: 10.1155/2015/745613] [Citation(s) in RCA: 139] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 09/11/2014] [Accepted: 09/11/2014] [Indexed: 01/08/2023]
Abstract
An insult to the brain (such as the first seizure) causes excitotoxicity, neuroinflammation, and production of reactive oxygen/nitrogen species (ROS/RNS). ROS and RNS produced during status epilepticus (SE) overwhelm the mitochondrial natural antioxidant defense mechanism. This leads to mitochondrial dysfunction and damage to the mitochondrial DNA. This in turn affects synthesis of various enzyme complexes that are involved in electron transport chain. Resultant effects that occur during epileptogenesis include lipid peroxidation, reactive gliosis, hippocampal neurodegeneration, reorganization of neural networks, and hypersynchronicity. These factors predispose the brain to spontaneous recurrent seizures (SRS), which ultimately establish into temporal lobe epilepsy (TLE). This review discusses some of these issues. Though antiepileptic drugs (AEDs) are beneficial to control/suppress seizures, their long term usage has been shown to increase ROS/RNS in animal models and human patients. In established TLE, ROS/RNS are shown to be harmful as they can increase the susceptibility to SRS. Further, in this paper, we review briefly the data from animal models and human TLE patients on the adverse effects of antiepileptic medications and the plausible ameliorating effects of antioxidants as an adjunct therapy.
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Affiliation(s)
- Sreekanth Puttachary
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011-1250, USA
| | - Shaunik Sharma
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011-1250, USA
| | - Sara Stark
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011-1250, USA
| | - Thimmasettappa Thippeswamy
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011-1250, USA
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Cao L, Bie X, Huo S, Du J, Liu L, Song W. Effects of diazepam on glutamatergic synaptic transmission in the hippocampal CA1 area of rats with traumatic brain injury. Neural Regen Res 2015; 9:1897-901. [PMID: 25558239 PMCID: PMC4281428 DOI: 10.4103/1673-5374.145357] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2014] [Indexed: 01/20/2023] Open
Abstract
The activity of the Schaffer collaterals of hippocampal CA3 neurons and hippocampal CA1 neurons has been shown to increase after fluid percussion injury. Diazepam can inhibit the hyperexcitability of rat hippocampal neurons after injury, but the mechanism by which it affects excitatory synaptic transmission remains poorly understood. Our results showed that diazepam treatment significantly increased the slope of input-output curves in rat neurons after fluid percussion injury. Diazepam significantly decreased the numbers of spikes evoked by super stimuli in the presence of 15 μmol/L bicuculline, indicating the existence of inhibitory pathways in the injured rat hippocampus. Diazepam effectively increased the paired-pulse facilitation ratio in the hippocampal CA1 region following fluid percussion injury, reduced miniature excitatory postsynaptic potentials, decreased action-potential-dependent glutamine release, and reversed spontaneous glutamine release. These data suggest that diazepam could decrease the fluid percussion injury-induced enhancement of excitatory synaptic transmission in the rat hippocampal CA1 area.
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Affiliation(s)
- Lei Cao
- Department of Functional Neurosurgery, Xi'an Red Cross Hospital, Xi'an, Shaanxi Province, China ; Department of Rehabilitation Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Xiaohua Bie
- Department of Functional Neurosurgery, Xi'an Red Cross Hospital, Xi'an, Shaanxi Province, China
| | - Su Huo
- Department of Rehabilitation Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Jubao Du
- Department of Rehabilitation Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Lin Liu
- Department of Rehabilitation Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Weiqun Song
- Department of Rehabilitation Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China
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Prager EM, Aroniadou-Anderjaska V, Almeida-Suhett CP, Figueiredo TH, Apland JP, Rossetti F, Olsen CH, Braga MFM. The recovery of acetylcholinesterase activity and the progression of neuropathological and pathophysiological alterations in the rat basolateral amygdala after soman-induced status epilepticus: relation to anxiety-like behavior. Neuropharmacology 2014; 81:64-74. [PMID: 24486384 PMCID: PMC4005290 DOI: 10.1016/j.neuropharm.2014.01.035] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Revised: 12/12/2013] [Accepted: 01/21/2014] [Indexed: 02/05/2023]
Abstract
Organophosphorus nerve agents are powerful neurotoxins that irreversibly inhibit acetylcholinesterase (AChE) activity. One of the consequences of AChE inhibition is the generation of seizures and status epilepticus (SE), which cause brain damage, resulting in long-term neurological and behavioral deficits. Increased anxiety is the most common behavioral abnormality after nerve agent exposure. This is not surprising considering that the amygdala, and the basolateral nucleus of the amygdala (BLA) in particular, plays a central role in anxiety, and this structure suffers severe damage by nerve agent-induced seizures. In the present study, we exposed male rats to the nerve agent soman, at a dose that induce SE, and determined the time course of recovery of AChE activity, along with the progression of neuropathological and pathophysiological alterations in the BLA, during a 30-day period after exposure. Measurements were taken at 24 h, 7 days, 14 days, and 30 days after exposure, and at 14 and 30 days, anxiety-like behavior was also evaluated. We found that more than 90% of AChE is inhibited at the onset of SE, and AChE inhibition remains at this level 24 h later, in the BLA, as well as in the hippocampus, piriform cortex, and prelimbic cortex, which we analyzed for comparison. AChE activity recovered by day 7 in the BLA and day 14 in the other three regions. Significant neuronal loss and neurodegeneration were present in the BLA at 24 h and throughout the 30-day period. There was no significant loss of GABAergic interneurons in the BLA at 24 h post-exposure. However, by day 7, the number of GABAergic interneurons in the BLA was reduced, and at 14 and 30 days after soman, the ratio of GABAergic interneurons to the total number of neurons was lower compared to controls. Anxiety-like behavior in the open-field and the acoustic startle response tests was increased at 14 and 30 days post-exposure. Accompanying pathophysiological alterations in the BLA - studied in in vitro brain slices - included a reduction in the amplitude of field potentials evoked by stimulation of the external capsule, along with prolongation of their time course and an increase in the paired-pulse ratio. Long-term potentiation was impaired at 24 h, 7 days, and 14 days post-exposure. The loss of GABAergic interneurons in the BLA and the decreased interneuron to total number of neurons ratio may be the primary cause of the development of anxiety after nerve agent exposure.
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Affiliation(s)
- 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; Program in Neuroscience, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, 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, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Program in Neuroscience, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
| | - Camila P Almeida-Suhett
- 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; Program in Neuroscience, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, 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
| | - James P Apland
- Neurotoxicology Branch, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, USA
| | - Franco Rossetti
- 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
| | - Cara H Olsen
- Biostatistics Consulting Center, 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, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Program in Neuroscience, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
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Acetylcholinesterase inhibition in the basolateral amygdala plays a key role in the induction of status epilepticus after soman exposure. Neurotoxicology 2013; 38:84-90. [PMID: 23817175 DOI: 10.1016/j.neuro.2013.06.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 06/20/2013] [Accepted: 06/20/2013] [Indexed: 11/21/2022]
Abstract
Exposure to nerve agents induces intense seizures (status epilepticus, SE), which cause brain damage or death. Identification of the brain regions that are critical for seizure initiation after nerve agent exposure, along with knowledge of the physiology of these regions, can facilitate the development of pretreatments and treatments that will successfully prevent or limit the development of seizures and brain damage. It is well-established that seizure initiation is due to excessive cholinergic activity triggered by the nerve agent-induced irreversible inhibition of acetylcholinesterase (AChE). Therefore, the reason that when animals are exposed to lethal doses of a nerve agent, a small proportion of these animals do not develop seizures, may have to do with failure of the nerve agent to inhibit AChE in brain areas that play a key role in seizure initiation and propagation. In the present study, we compared AChE activity in the basolateral amygdala (BLA), hippocampus, and piriform cortex of rats that developed SE (SE rats) after administration of the nerve agent soman (154μg/kg) to AChE activity in these brain regions of rats that received the same dose of soman but did not develop SE (no-SE rats). The levels of AChE activity were measured at the onset of SE in SE rats, 30min after soman administration in no-SE rats, as well as in controls which received saline in place of soman. In the control group, AChE activity was significantly higher in the BLA compared to the hippocampus and piriform cortex. Compared to controls, AChE activity was dramatically lower in the hippocampus and the piriform cortex of both the SE rats and the no-SE rats, but AChE activity in the BLA was reduced only in the SE rats. Consistent with the notion that soman-induced neuropathology is due to intense seizures, rather than due to a direct neurotoxic effect of soman, no-SE rats did not present any neuronal loss or degeneration, 7 days after exposure. The results suggest that inhibition of AChE activity in the BLA is necessary for the generation of seizures after nerve agent exposure, and provide strong support to the view that the amygdala is a key brain region for the induction of seizures by nerve agents.
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Dorandeu F, Barbier L, Dhote F, Testylier G, Carpentier P. Ketamine combinations for the field treatment of soman-induced self-sustaining status epilepticus. Review of current data and perspectives. Chem Biol Interact 2013; 203:154-9. [DOI: 10.1016/j.cbi.2012.09.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Revised: 09/25/2012] [Accepted: 09/26/2012] [Indexed: 12/21/2022]
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Gräff J, Tsai LH. Histone acetylation: molecular mnemonics on the chromatin. Nat Rev Neurosci 2013; 14:97-111. [PMID: 23324667 DOI: 10.1038/nrn3427] [Citation(s) in RCA: 430] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Long-lasting memories require specific gene expression programmes that are, in part, orchestrated by epigenetic mechanisms. Of the epigenetic modifications identified in cognitive processes, histone acetylation has spurred considerable interest. Whereas increments in histone acetylation have consistently been shown to favour learning and memory, a lack thereof has been causally implicated in cognitive impairments in neurodevelopmental disorders, neurodegeneration and ageing. As histone acetylation and cognitive functions can be pharmacologically restored by histone deacetylase inhibitors, this epigenetic modification might constitute a molecular memory aid on the chromatin and, by extension, a new template for therapeutic interventions against cognitive frailty.
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Affiliation(s)
- Johannes Gräff
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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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: 87] [Impact Index Per Article: 7.3] [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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