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Figueiredo TH, Aroniadou-Anderjaska V, Apland JP, Rossetti K, Braga MFM. Delayed tezampanel and caramiphen treatment but not midazolam protects against long-term neuropathology after soman exposure. Exp Biol Med (Maywood) 2023; 248:612-623. [PMID: 37300407 PMCID: PMC10350803 DOI: 10.1177/15353702231171911] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Accepted: 03/09/2023] [Indexed: 06/12/2023] Open
Abstract
Prolonged status epilepticus (SE) can cause brain damage; therefore, treatment must be administered promptly after seizure onset to limit SE duration and prevent neuropathology. Timely treatment of SE is not always feasible; this would be particularly true in a mass exposure to an SE-inducing agent such as a nerve agent. Therefore, the availability of anticonvulsant treatments that have neuroprotective efficacy even if administered with a delay after SE onset is an imperative. Here, we compared the long-term neuropathology resulting from acutely exposing 21-day-old male and female rats to the nerve agent soman, and treating them with midazolam (3 mg/kg) or co-administration of tezampanel (10 mg/kg) and caramiphen (50 mg/kg), at 1 h postexposure (~50 min after SE onset). Midazolam-treated rats had significant neuronal degeneration in limbic structures, mainly at one month postexposure, followed by neuronal loss in the basolateral amygdala and the CA1 hippocampal area. Neuronal loss resulted in significant amygdala and hippocampal atrophy, deteriorating from one to six months postexposure. Rats treated with tezampanel-caramiphen had no evidence of neuropathology, except for neuronal loss in the basolateral amygdala at the six-month timepoint. Anxiety was increased only in the midazolam-treated rats, at one, three, and six months postexposure. Spontaneous recurrent seizures appeared only in midazolam-treated rats, at three and six months postexposure in males and only at six months in females. These findings suggest that delayed treatment of nerve agent-induced SE with midazolam may result in long-lasting or permanent brain damage, while antiglutamatergic anticonvulsant treatment consisting of tezampanel and caramiphen may provide full neuroprotection.
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Affiliation(s)
- Taiza H Figueiredo
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 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, Bethesda, MD 20814, USA
- Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - James P Apland
- Neuroscience Program, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, USA
| | - Katia Rossetti
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Maria FM Braga
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 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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2
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Figueiredo TH, Aroniadou-Anderjaska V, Pidoplichko VI, Apland JP, Braga MFM. Antiseizure and Neuroprotective Efficacy of Midazolam in Comparison with Tezampanel (LY293558) against Soman-Induced Status Epilepticus. TOXICS 2022; 10:409. [PMID: 35893842 PMCID: PMC9330837 DOI: 10.3390/toxics10080409] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 07/19/2022] [Accepted: 07/20/2022] [Indexed: 12/12/2022]
Abstract
Acute exposure to nerve agents induces status epilepticus (SE), which can cause death or long-term brain damage. Diazepam is approved by the FDA for the treatment of nerve agent-induced SE, and midazolam (MDZ) is currently under consideration to replace diazepam. However, animal studies have raised questions about the neuroprotective efficacy of benzodiazepines. Here, we compared the antiseizure and neuroprotective efficacy of MDZ (5 mg/kg) with that of tezampanel (LY293558; 10 mg/kg), an AMPA/GluK1 receptor antagonist, administered 1 h after injection of the nerve agent, soman (1.2 × LD50), in adult male rats. Both of the anticonvulsants promptly stopped SE, with MDZ having a more rapid effect. However, SE reoccurred to a greater extent in the MDZ-treated group, resulting in a significantly longer total duration of SE within 24 h post-exposure compared with the LY293558-treated group. The neuroprotective efficacy of the two drugs was studied in the basolateral amygdala, 30 days post-exposure. Significant neuronal and inter-neuronal loss, reduced ratio of interneurons to the total number of neurons, and reduction in spontaneous inhibitory postsynaptic currents accompanied by increased anxiety were found in the MDZ-treated group. The rats treated with LY293558 did not differ from the control rats (not exposed to soman) in any of these measurements. Thus, LY293558 has significantly greater efficacy than midazolam in protecting against prolonged seizures and brain damage caused by acute nerve agent exposure.
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Affiliation(s)
- Taiza H. Figueiredo
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA; (T.H.F.); (V.A.-A.); (V.I.P.)
| | - Vassiliki Aroniadou-Anderjaska
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA; (T.H.F.); (V.A.-A.); (V.I.P.)
- Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Volodymyr I. Pidoplichko
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA; (T.H.F.); (V.A.-A.); (V.I.P.)
| | - James P. Apland
- Neuroscience Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Aberdeen, MD 21010, USA;
| | - Maria F. M. Braga
- Department of Anatomy, Physiology, and Genetics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA; (T.H.F.); (V.A.-A.); (V.I.P.)
- Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
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3
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Quijano Cardé NA, Perez EE, Feinn R, Kranzler HR, De Biasi M. Antagonism of GluK1-containing kainate receptors reduces ethanol consumption by modulating ethanol reward and withdrawal. Neuropharmacology 2021; 199:108783. [PMID: 34509497 PMCID: PMC8572579 DOI: 10.1016/j.neuropharm.2021.108783] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 08/18/2021] [Accepted: 09/06/2021] [Indexed: 10/20/2022]
Abstract
Alcohol use disorder (AUD) is a neuropsychiatric condition affecting millions of people worldwide. Topiramate (TPM) is an antiepileptic drug that has been shown to reduce ethanol drinking in humans. However, TPM is associated with a variety of adverse effects due to its interaction with many receptor systems and intracellular pathways. GluK1-containing kainate receptors (GluK1*KARs) are non-selectively inhibited by TPM, and genetic association studies suggest that this receptor system could be targeted to reduce drinking in AUD patients. We examined the efficacy of LY466195, a selective inhibitor of GluK1*KAR, in reducing ethanol consumption in the intermittent two-bottle choice paradigm in mice. The effect of LY466195 on various ethanol-related phenotypes was investigated by quantification of alcohol intake, physical signs of withdrawal, conditioned place preference (CPP) and in vivo microdialysis in the nucleus accumbens. Selective GluK1*KAR inhibition reduced ethanol intake and preference in a dose-dependent manner. LY466195 treatment attenuated the physical manifestations of ethanol withdrawal and influenced the rewarding properties of ethanol. Interestingly, LY466195 injection also normalized changes in dopamine levels in response to acute ethanol in ethanol-dependent mice, but had no effect in ethanol-naïve mice, suggesting ethanol state-dependent effects. The data point to GluK1*KARs as an attractive pharmacological target for the treatment of AUD.
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Affiliation(s)
- Natalia A Quijano Cardé
- Pharmacology Graduate Group, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Erika E Perez
- Department of Neuroscience, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Richard Feinn
- Department of Medical Sciences, Frank H Netter School of Medicine, Quinnipiac University, CTl Sciences, USA
| | - Henry R Kranzler
- Center for Studies of Addiction, Department of Psychiatry, Perelman School of Medicine of the University of Pennsylvania and VISN 4 MIRECC, Crescenz VAMC, Philadelphia, PA, 19104, USA; Department of Psychiatry, Perelman School of Medicine of the University of Pennsylvania, USA
| | - Mariella De Biasi
- Pharmacology Graduate Group, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, 19104, USA; Department of Psychiatry, Perelman School of Medicine of the University of Pennsylvania, USA.
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4
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Wang S, He H, Long J, Sui X, Yang J, Lin G, Wang Q, Wang Y, Luo Y. TRPV4 Regulates Soman-Induced Status Epilepticus and Secondary Brain Injury via NMDA Receptor and NLRP3 Inflammasome. Neurosci Bull 2021; 37:905-920. [PMID: 33761112 DOI: 10.1007/s12264-021-00662-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 12/06/2020] [Indexed: 01/12/2023] Open
Abstract
Nerve agents are used in civil wars and terrorist attacks, posing a threat to public safety. Acute exposure to nerve agents such as soman (GD) causes serious brain damage, leading to death due to intense seizures induced by acetylcholinesterase inhibition and neuronal injury resulting from increased excitatory amino-acid levels and neuroinflammation. However, data on the anticonvulsant and neuroprotective efficacies of currently-used countermeasures are limited. Here, we evaluated the potential effects of transient receptor vanilloid 4 (TRPV4) in the treatment of soman-induced status epilepticus (SE) and secondary brain injury. We demonstrated that TRPV4 expression was markedly up-regulated in rat hippocampus after soman-induced seizures. Administration of the TRPV4 antagonist GSK2193874 prior to soman exposure significantly decreased the mortality rate in rats and reduced SE intensity. TRPV4-knockout mice also showed lower incidence of seizures and higher survival rates than wild-type mice following soman exposure. Further in vivo and in vitro experiments demonstrated that blocking TRPV4 prevented NMDA receptor-mediated glutamate excitotoxicity. The protein levels of the NLRP3 inflammasome complex and its downstream cytokines IL-1β and IL-18 increased in soman-exposed rat hippocampus. However, TRPV4 inhibition or deletion markedly reversed the activation of the NLRP3 inflammasome pathway. In conclusion, our study suggests that the blockade of TRPV4 protects against soman exposure and reduces brain injury following SE by decreasing NMDA receptor-mediated excitotoxicity and NLRP3-mediated neuroinflammation. To our knowledge, this is the first study regarding the "dual-switch" function of TRPV4 in the treatment of soman intoxication.
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Affiliation(s)
- Shuai Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing, 100850, China
| | - Huanhuan He
- State Key Laboratory of Toxicology and Medical Countermeasures, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing, 100850, China
| | - Jianhai Long
- State Key Laboratory of Toxicology and Medical Countermeasures, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing, 100850, China
| | - Xin Sui
- State Key Laboratory of Toxicology and Medical Countermeasures, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing, 100850, China
| | - Jun Yang
- State Key Laboratory of Toxicology and Medical Countermeasures, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing, 100850, China
| | - Guodong Lin
- State Key Laboratory of Toxicology and Medical Countermeasures, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing, 100850, China
| | - Qian Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing, 100850, China
| | - Yongan Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing, 100850, China.
| | - Yuan Luo
- State Key Laboratory of Toxicology and Medical Countermeasures, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing, 100850, China.
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5
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Aroniadou-Anderjaska V, Apland JP, Figueiredo TH, De Araujo Furtado M, Braga MF. Acetylcholinesterase inhibitors (nerve agents) as weapons of mass destruction: History, mechanisms of action, and medical countermeasures. Neuropharmacology 2020; 181:108298. [DOI: 10.1016/j.neuropharm.2020.108298] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 08/21/2020] [Accepted: 09/02/2020] [Indexed: 02/07/2023]
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6
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Casillas‐Espinosa PM, Ali I, O'Brien TJ. Neurodegenerative pathways as targets for acquired epilepsy therapy development. Epilepsia Open 2020; 5:138-154. [PMID: 32524040 PMCID: PMC7278567 DOI: 10.1002/epi4.12386] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 02/13/2020] [Accepted: 02/24/2020] [Indexed: 12/16/2022] Open
Abstract
There is a growing body of clinical and experimental evidence that neurodegenerative diseases and epileptogenesis after an acquired brain insult may share common etiological mechanisms. Acquired epilepsy commonly develops as a comorbid condition in patients with neurodegenerative diseases such as Alzheimer's disease, although it is likely much under diagnosed in practice. Progressive neurodegeneration has also been described after traumatic brain injury, stroke, and other forms of brain insults. Moreover, recent evidence has shown that acquired epilepsy is often a progressive disorder that is associated with the development of drug resistance, cognitive decline, and worsening of other neuropsychiatric comorbidities. Therefore, new pharmacological therapies that target neurobiological pathways that underpin neurodegenerative diseases have potential to have both an anti-epileptogenic and disease-modifying effect on the seizures in patients with acquired epilepsy, and also mitigate the progressive neurocognitive and neuropsychiatric comorbidities. Here, we review the neurodegenerative pathways that are plausible targets for the development of novel therapies that could prevent the development or modify the progression of acquired epilepsy, and the supporting published experimental and clinical evidence.
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Affiliation(s)
- Pablo M. Casillas‐Espinosa
- Departments of Neuroscience and MedicineCentral Clinical SchoolMonash UniversityMelbourneVic.Australia
- Department of MedicineThe Royal Melbourne HospitalThe University of MelbourneMelbourneVic.Australia
| | - Idrish Ali
- Departments of Neuroscience and MedicineCentral Clinical SchoolMonash UniversityMelbourneVic.Australia
- Department of MedicineThe Royal Melbourne HospitalThe University of MelbourneMelbourneVic.Australia
| | - Terence J. O'Brien
- Departments of Neuroscience and MedicineCentral Clinical SchoolMonash UniversityMelbourneVic.Australia
- Department of MedicineThe Royal Melbourne HospitalThe University of MelbourneMelbourneVic.Australia
- Department of NeurologyThe Alfred HospitalMelbourneVic.Australia
- Department of NeurologyThe Royal Melbourne HospitalParkvilleVic.Australia
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7
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De Araujo Furtado M, Aroniadou-Anderjaska V, Figueiredo TH, Apland JP, Braga MFM. Electroencephalographic analysis in soman-exposed 21-day-old rats and the effects of midazolam or LY293558 with caramiphen. Ann N Y Acad Sci 2020; 1479:122-133. [PMID: 32237259 DOI: 10.1111/nyas.14331] [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: 12/30/2019] [Revised: 02/25/2020] [Accepted: 02/27/2020] [Indexed: 12/19/2022]
Abstract
Acute nerve agent exposure induces status epilepticus (SE), which can cause brain damage or death. Research aiming at developing effective therapies for controlling nerve agent-induced SE is commonly performed in adult rats. The characteristics of nerve agent-induced SE in young rats are less clear; relevant knowledge is necessary for developing effective pediatric therapies. Here, we have used electroencephalographic (EEG) recordings and analysis to study seizures in postnatal day 21 rats exposed to 1.2 × LD50 of soman, and compared the antiseizure efficacy of midazolam (MDZ)-currently considered by the Food and Drug Administration to replace diazepam for treating SE in victims of nerve agent exposure-with that of LY293558, an AMPA/GluK1 receptor antagonist, administered in combination with caramiphen, an antimuscarinic with N-methyl-d-aspartate receptor antagonistic properties. Prolonged SE developed in 80% of the rats and was reflected in behavioral seizures/convulsions. Both MDZ and LY293558 + caramiphen stopped the SE induced by soman, but there was a significant recurrence of seizures within 24 h postexposure only in the MDZ-treated group, as revealed in the raw EEG data and their representation in the frequency domain using a fast Fourier transform and in spectral analysis over 24 hours. In contrast to the high efficacy of LY293558 + caramiphen, MDZ is not an effective treatment for SE induced by soman in young animals.
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Affiliation(s)
- Marcio De Araujo Furtado
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Vassiliki Aroniadou-Anderjaska
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland.,Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Taiza H Figueiredo
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - James P Apland
- Neurotoxicology Branch, the United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland
| | - Maria F M Braga
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland.,Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
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8
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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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9
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Apland JP, Aroniadou-Anderjaska V, Figueiredo TH, Pidoplichko VI, Rossetti K, Braga MFM. Comparing the Antiseizure and Neuroprotective Efficacy of LY293558, Diazepam, Caramiphen, and LY293558-Caramiphen Combination against Soman in a Rat Model Relevant to the Pediatric Population. J Pharmacol Exp Ther 2018; 365:314-326. [PMID: 29467308 PMCID: PMC5878669 DOI: 10.1124/jpet.117.245969] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 02/08/2018] [Indexed: 12/13/2022] Open
Abstract
The currently Food and Drug Administration-approved anticonvulsant for the treatment of status epilepticus (SE) induced by nerve agents is the benzodiazepine diazepam; however, diazepam does not appear to offer neuroprotective benefits. This is of particular concern with respect to the protection of children because, in the developing brain, synaptic transmission mediated via GABAA receptors, the target of diazepam, is weak. In the present study, we exposed 21-day-old male rats to 1.2 × LD50 soman and compared the antiseizure, antilethality, and neuroprotective efficacy of diazepam (10 mg/kg), LY293558 (an AMPA/GluK1 receptor antagonist; 15 mg/kg), caramiphen (CRM, an antimuscarinic with NMDA receptor-antagonistic properties; 50 mg/kg), and LY293558 (15 mg/kg) + CRM (50 mg/kg), administered 1 hour after exposure. Diazepam, LY293558, and LY293558 + CRM, but not CRM alone, terminated SE; LY293558 + CRM treatment acted significantly faster and produced a survival rate greater than 85%. Thirty days after soman exposure, neurodegeneration in limbic regions was most severe in the CRM-treated group, minimal to severe-depending on the region-in the diazepam group, absent to moderate in the LY293558-treated group, and totally absent in the LY293558 + CRM group. Amygdala and hippocampal atrophy, a severe reduction in spontaneous inhibitory activity in the basolateral amygdala, and increased anxiety-like behavior in the open-field and acoustic startle response tests were present in the diazepam and CRM groups, whereas the LY293558 and LY293558 + CRM groups did not differ from controls. The combined administration of LY293558 and CRM, by blocking mainly AMPA, GluK1, and NMDA receptors, is a very effective anticonvulsant and neuroprotective therapy against soman in young rats.
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Affiliation(s)
- James P Apland
- Neuroscience Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.); and Departments of Anatomy, Physiology, and Genetics (V.A.-A., T.H.F., V.I.P., K.R., M.F.M.B.) and Psychiatry (V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Vassiliki Aroniadou-Anderjaska
- Neuroscience Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.); and Departments of Anatomy, Physiology, and Genetics (V.A.-A., T.H.F., V.I.P., K.R., M.F.M.B.) and Psychiatry (V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Taiza H Figueiredo
- Neuroscience Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.); and Departments of Anatomy, Physiology, and Genetics (V.A.-A., T.H.F., V.I.P., K.R., M.F.M.B.) and Psychiatry (V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Volodymyr I Pidoplichko
- Neuroscience Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.); and Departments of Anatomy, Physiology, and Genetics (V.A.-A., T.H.F., V.I.P., K.R., M.F.M.B.) and Psychiatry (V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Katia Rossetti
- Neuroscience Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.); and Departments of Anatomy, Physiology, and Genetics (V.A.-A., T.H.F., V.I.P., K.R., M.F.M.B.) and Psychiatry (V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Maria F M Braga
- Neuroscience Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.); and Departments of Anatomy, Physiology, and Genetics (V.A.-A., T.H.F., V.I.P., K.R., M.F.M.B.) and Psychiatry (V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
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10
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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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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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Aroniadou-Anderjaska V, Figueiredo TH, Apland JP, Prager EM, Pidoplichko VI, Miller SL, Braga MFM. Long-term neuropathological and behavioral impairments after exposure to nerve agents. Ann N Y Acad Sci 2016; 1374:17-28. [PMID: 27002925 DOI: 10.1111/nyas.13028] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 01/15/2016] [Accepted: 01/25/2016] [Indexed: 01/11/2023]
Abstract
One of the deleterious effects of acute nerve agent exposure is the induction of status epilepticus (SE). If SE is not controlled effectively, it causes extensive brain damage. Here, we review the neuropathology observed after nerve agent-induced SE, as well as the ensuing pathophysiological, neurological, and behavioral alterations, with an emphasis on their time course and longevity. Limbic structures are particularly vulnerable to damage by nerve agent exposure. The basolateral amygdala (BLA), which appears to be a key site for seizure initiation upon exposure, suffers severe neuronal loss; however, GABAergic BLA interneurons display a delayed death, perhaps providing a window of opportunity for rescuing intervention. The end result is a long-term reduction of GABAergic activity in the BLA, with a concomitant increase in spontaneous excitatory activity; such pathophysiological alterations are not observed in the CA1 hippocampal area, despite the extensive neuronal loss. Hyperexcitability in the BLA may be at least in part responsible for the development of recurrent seizures and increased anxiety, while hippocampal damage may underlie the long-term memory impairments. Effective control of SE after nerve agent exposure, such that brain damage is also minimized, is paramount for preventing lasting neurological and behavioral deficits.
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Affiliation(s)
- Vassiliki Aroniadou-Anderjaska
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland.,Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Taiza H Figueiredo
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - James P Apland
- Neurotoxicology Branch, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland
| | - Eric M Prager
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Volodymyr I Pidoplichko
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Steven L Miller
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Maria F M Braga
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland.,Department of Psychiatry, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
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Miller SL, Aroniadou-Anderjaska V, Figueiredo TH, Prager EM, Almeida-Suhett CP, Apland JP, Braga MFM. A rat model of nerve agent exposure applicable to the pediatric population: The anticonvulsant efficacies of atropine and GluK1 antagonists. Toxicol Appl Pharmacol 2015; 284:204-16. [PMID: 25689173 DOI: 10.1016/j.taap.2015.02.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 01/30/2015] [Accepted: 02/07/2015] [Indexed: 12/27/2022]
Abstract
Inhibition of acetylcholinesterase (AChE) after nerve agent exposure induces status epilepticus (SE), which causes brain damage or death. The development of countermeasures appropriate for the pediatric population requires testing of anticonvulsant treatments in immature animals. In the present study, exposure of 21-day-old (P21) rats to different doses of soman, followed by probit analysis, produced an LD50 of 62μg/kg. The onset of behaviorally-observed SE was accompanied by a dramatic decrease in brain AChE activity; rats who did not develop SE had significantly less reduction of AChE activity in the basolateral amygdala than rats who developed SE. Atropine sulfate (ATS) at 2mg/kg, administered 20 min after soman exposure (1.2×LD50), terminated seizures. ATS at 0.5mg/kg, given along with an oxime within 1 min after exposure, allowed testing of anticonvulsants at delayed time-points. The AMPA/GluK1 receptor antagonist LY293558, or the specific GluK1 antagonist UBP302, administered 1h post-exposure, terminated SE. There were no degenerating neurons in soman-exposed P21 rats, but both the amygdala and the hippocampus were smaller than in control rats at 30 and 90days post-exposure; this pathology was not present in rats treated with LY293558. Behavioral deficits present at 30 days post-exposure, were also prevented by LY293558 treatment. Thus, in immature animals, a single injection of atropine is sufficient to halt nerve agent-induced seizures, if administered timely. Testing anticonvulsants at delayed time-points requires early administration of ATS at a low dose, sufficient to counteract only peripheral toxicity. LY293558 administered 1h post-exposure, prevents brain pathology and behavioral deficits.
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Affiliation(s)
- Steven L Miller
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Program in Neuroscience, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
| | - Vassiliki Aroniadou-Anderjaska
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Department of Psychiatry, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; 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.
| | - Eric M Prager
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Program in Neuroscience, 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, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Program in Neuroscience, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
| | - James P Apland
- Neurotoxicology Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, USA.
| | - Maria F M Braga
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Department of Psychiatry, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Program in Neuroscience, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
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Prager EM, Figueiredo TH, Long RP, Aroniadou-Anderjaska V, Apland JP, Braga MFM. LY293558 prevents soman-induced pathophysiological alterations in the basolateral amygdala and the development of anxiety. Neuropharmacology 2015; 89:11-8. [PMID: 25204221 PMCID: PMC4250288 DOI: 10.1016/j.neuropharm.2014.08.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 07/18/2014] [Accepted: 08/20/2014] [Indexed: 11/24/2022]
Abstract
Exposure to nerve agents can cause brain damage due to prolonged seizure activity, producing long-term behavioral deficits. We have previously shown that LY293558, a GluK1/AMPA receptor antagonist, is a very effective anticonvulsant and neuroprotectant against nerve agent exposure. In the present study, we examined whether the protection against nerve agent-induced seizures and neuropathology conferred by LY293558 translates into protection against pathophysiological alterations in the basolateral amygdala (BLA) and the development of anxiety, which is the most prevalent behavioral deficit resulting from exposure. LY293558 (15 mg/kg) was administered to rats, along with atropine and HI-6, at 20 min after exposure to soman (1.2 × LD50). At 24 h, 7 days, and 30 days after exposure, soman-exposed rats who did not receive LY293558 had reduced but prolonged evoked field potentials in the BLA, as well as increased paired-pulse ratio, suggesting neuronal damage and impaired synaptic inhibition; rats who received LY293558 did not differ from controls in these parameters. Long-term potentiation of synaptic transmission was impaired at 7 days after exposure in the soman-exposed rats who did not receive anticonvulsant treatment, but not in the LY293558-treated rats. Anxiety-like behavior assessed by the open field and acoustic startle response tests was increased in the soman-exposed rats at 30 and 90 days after exposure, while rats treated with LY293558 did not differ from controls. Along with our previous findings, the present data demonstrate the remarkable efficacy of LY293558 in counteracting nerve agent-induced seizures, neuropathology, pathophysiological alterations in the BLA, and anxiety-related behavioral deficits.
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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.
| | - 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.
| | - Robert P Long
- 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.
| | - James P Apland
- Neurotoxicology Branch, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, 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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Choice of approaches in developing novel medical countermeasures for nerve agent poisoning. Neurotoxicology 2014; 44:27-38. [DOI: 10.1016/j.neuro.2014.04.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 03/24/2014] [Accepted: 04/30/2014] [Indexed: 11/24/2022]
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17
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Apland JP, Aroniadou-Anderjaska V, Figueiredo TH, Rossetti F, Miller SL, Braga MFM. The limitations of diazepam as a treatment for nerve agent-induced seizures and neuropathology in rats: comparison with UBP302. J Pharmacol Exp Ther 2014; 351:359-72. [PMID: 25157087 DOI: 10.1124/jpet.114.217299] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Exposure to nerve agents induces prolonged status epilepticus (SE), causing brain damage or death. Diazepam (DZP) is the current US Food and Drug Administration-approved drug for the cessation of nerve agent-induced SE. Here, we compared the efficacy of DZP with that of UBP302 [(S)-3-(2-carboxybenzyl)willardiine; an antagonist of the kainate receptors that contain the GluK1 subunit] against seizures, neuropathology, and behavioral deficits induced by soman in rats. DZP, administered 1 hour or 2 hours postexposure, terminated the SE, but seizures returned; thus, the total duration of SE within 24 hours after soman exposure was similar to (DZP at 1 hour) or longer than (DZP at 2 hours) that in the soman-exposed rats that did not receive the anticonvulsant. Compared with DZP, UBP302 stopped SE with a slower time course, but dramatically reduced the total duration of SE within 24 hours. Neuropathology and behavior were assessed in the groups that received anticonvulsant treatment 1 hour after exposure. UBP302, but not DZP, reduced neuronal degeneration in a number of brain regions, as well as neuronal loss in the basolateral amygdala and the CA1 hippocampal area, and prevented interneuronal loss in the basolateral amygdala. Anxiety-like behavior was assessed in the open field and by the acoustic startle response 30 days after soman exposure. The results showed that anxiety-like behavior was increased in the DZP-treated group and in the group that did not receive anticonvulsant treatment, but not in the UBP302-treated group. The results argue against the use of DZP for the treatment of nerve agent-induced seizures and brain damage and suggest that targeting GluK1-containing receptors is a more effective approach.
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Affiliation(s)
- James P Apland
- Neurotoxicology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.); and Department of Anatomy, Physiology, and Genetics (V.A.-A., T.H.F., F.R., S.L.M., M.F.M.B.) and Department of Psychiatry (V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Vassiliki Aroniadou-Anderjaska
- Neurotoxicology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.); and Department of Anatomy, Physiology, and Genetics (V.A.-A., T.H.F., F.R., S.L.M., M.F.M.B.) and Department of Psychiatry (V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Taiza H Figueiredo
- Neurotoxicology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.); and Department of Anatomy, Physiology, and Genetics (V.A.-A., T.H.F., F.R., S.L.M., M.F.M.B.) and Department of Psychiatry (V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Franco Rossetti
- Neurotoxicology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.); and Department of Anatomy, Physiology, and Genetics (V.A.-A., T.H.F., F.R., S.L.M., M.F.M.B.) and Department of Psychiatry (V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Steven L Miller
- Neurotoxicology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.); and Department of Anatomy, Physiology, and Genetics (V.A.-A., T.H.F., F.R., S.L.M., M.F.M.B.) and Department of Psychiatry (V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Maria F M Braga
- Neurotoxicology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland (J.P.A.); and Department of Anatomy, Physiology, and Genetics (V.A.-A., T.H.F., F.R., S.L.M., M.F.M.B.) and Department of Psychiatry (V.A.-A., M.F.M.B.), F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
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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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Hanada T. The discovery and development of perampanel for the treatment of epilepsy. Expert Opin Drug Discov 2014; 9:449-58. [DOI: 10.1517/17460441.2014.891580] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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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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