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Harkins J, Langston J, Keith ZM, Munoz C, Acon-Chen C, Shih TM. Learning and memory function preserved by delayed A 1 adenosine receptor agonist treatment following soman intoxication in rats and a humanized esterase mouse model. Neuropharmacology 2024; 253:109983. [PMID: 38704023 PMCID: PMC11132435 DOI: 10.1016/j.neuropharm.2024.109983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 04/23/2024] [Accepted: 05/01/2024] [Indexed: 05/06/2024]
Abstract
Exposure to organophosphorus compounds, such as soman (GD), cause widespread toxic effects, sustained status epilepticus, neuropathology, and death. The A1 adenosine receptor agonist N-bicyclo-(2.2.1)-hept-2-yl-5'-chloro-5'-deoxyadenosine (ENBA), when given 1 min after GD exposure, provides neuroprotection and prevents behavioral impairments. Here, we tested the ability of ENBA at delayed treatment times to improve behavioral outcomes via a two-way active avoidance task in two male animal models, each consisting of saline and GD exposure groups. In a rat model, animals received medical treatments (atropine sulfate [A], 2-PAM [P], and midazolam [MDZ]) or AP + MDZ + ENBA at 15 or 30 min after seizure onset and were subjected to behavioral testing for up to 14 days. In a human acetylcholinesterase knock-in serum carboxylesterase knock-out mouse model, animals received AP, AP + MDZ, AP + ENBA, or AP + MDZ + ENBA at 15 min post seizure onset and were subjected to the behavioral task on days 7 and 14. In rats, the GD/AP + MDZ + ENBA group recovered to saline-exposed avoidance levels while the GD/AP + MDZ group did not. In mice, in comparison with GD/AP + MDZ group, the GD/AP + MDZ + ENBA showed decreases in escape latency, response latency, and pre-session crossings, as well as increases in avoidances. In both models, only ENBA-treated groups showed control level inter-trial interval crossings by day 14. Our findings suggest that ENBA, alone and as an adjunct to medical treatments, can improve behavioral and cognitive outcomes when given at delayed time points after GD intoxication.
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Affiliation(s)
- Joshua Harkins
- Medical Toxicology Research Division, U.S. Army Medical Research Institute of Chemical Defense, 8350 Ricketts Point Road, Aberdeen Proving Ground, MD, 21010-5400, USA.
| | - Jeffrey Langston
- Medical Toxicology Research Division, U.S. Army Medical Research Institute of Chemical Defense, 8350 Ricketts Point Road, Aberdeen Proving Ground, MD, 21010-5400, USA.
| | - Zora-Maya Keith
- Medical Toxicology Research Division, U.S. Army Medical Research Institute of Chemical Defense, 8350 Ricketts Point Road, Aberdeen Proving Ground, MD, 21010-5400, USA.
| | - Crystal Munoz
- Medical Toxicology Research Division, U.S. Army Medical Research Institute of Chemical Defense, 8350 Ricketts Point Road, Aberdeen Proving Ground, MD, 21010-5400, USA.
| | - Cindy Acon-Chen
- Medical Toxicology Research Division, U.S. Army Medical Research Institute of Chemical Defense, 8350 Ricketts Point Road, Aberdeen Proving Ground, MD, 21010-5400, USA.
| | - Tsung-Ming Shih
- Medical Toxicology Research Division, U.S. Army Medical Research Institute of Chemical Defense, 8350 Ricketts Point Road, Aberdeen Proving Ground, MD, 21010-5400, USA.
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Moghe M, Kim SS, Guan M, Rait A, Pirollo KF, Harford JB, Chang EH. scL-2PAM: A Novel Countermeasure That Ameliorates Neuroinflammation and Neuronal Losses in Mice Exposed to an Anticholinesterase Organophosphate. Int J Mol Sci 2024; 25:7539. [PMID: 39062781 PMCID: PMC11276659 DOI: 10.3390/ijms25147539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2024] [Revised: 07/01/2024] [Accepted: 07/05/2024] [Indexed: 07/28/2024] Open
Abstract
Due to their inhibition of acetylcholinesterase, organophosphates are among the most toxic of chemicals. Pralidoxime (a.k.a 2-PAM) is the only acetylcholinesterase reactivator approved in the U.S., but 2-PAM only poorly traverses the blood-brain barrier. Previously, we have demonstrated that scL-2PAM, a nanoformulation designed to enter the brain via receptor-mediated transcytosis, is superior to unencapsulated 2-PAM for reactivating brain acetylcholinesterase, ameliorating cholinergic crisis, and improving survival rates for paraoxon-exposed mice. Here, we employ histology and transcriptome analyses to assess the ability of scL-2PAM to prevent neurological sequelae including microglial activation, expression of inflammatory cytokines, and ultimately loss of neurons in mice surviving paraoxon exposures. Levels of the mRNA encoding chemokine ligand 2 (CCL2) were significantly upregulated after paraoxon exposures, with CCL2 mRNA levels in the brain correlating well with the intensity and duration of cholinergic symptoms. Our nanoformulation of 2-PAM was found to be superior to unencapsulated 2-PAM in reducing the levels of the CCL2 transcript. Moreover, brain histology revealed that scL-2PAM was more effective than unencapsulated 2-PAM in preventing microglial activation and the subsequent loss of neurons. Thus, scL-2PAM appears to be a new and improved countermeasure for reducing neuroinflammation and mitigating brain damage in survivors of organophosphate exposures.
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Affiliation(s)
- Manish Moghe
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA; (M.M.); (A.R.); (K.F.P.)
| | - Sang-Soo Kim
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA; (M.M.); (A.R.); (K.F.P.)
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University Medical Center, Washington, DC 20057, USA
- SynerGene Therapeutics, Inc., Potomac, MD 20854, USA;
| | - Miaoyin Guan
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA; (M.M.); (A.R.); (K.F.P.)
| | - Antonina Rait
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA; (M.M.); (A.R.); (K.F.P.)
| | - Kathleen F. Pirollo
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA; (M.M.); (A.R.); (K.F.P.)
| | | | - Esther H. Chang
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA; (M.M.); (A.R.); (K.F.P.)
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University Medical Center, Washington, DC 20057, USA
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Andrew PM, Feng W, Calsbeek JJ, Antrobus SP, Cherednychenko GA, MacMahon JA, Bernardino PN, Liu X, Harvey DJ, Lein PJ, Pessah IN. The α4 Nicotinic Acetylcholine Receptor Is Necessary for the Initiation of Organophosphate-Induced Neuronal Hyperexcitability. TOXICS 2024; 12:263. [PMID: 38668486 PMCID: PMC11054284 DOI: 10.3390/toxics12040263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 03/20/2024] [Accepted: 03/27/2024] [Indexed: 04/29/2024]
Abstract
Acute intoxication with organophosphorus (OP) cholinesterase inhibitors can produce seizures that rapidly progress to life-threatening status epilepticus. Significant research effort has been focused on investigating the involvement of muscarinic acetylcholine receptors (mAChRs) in OP-induced seizure activity. In contrast, there has been far less attention on nicotinic AChRs (nAChRs) in this context. Here, we address this data gap using a combination of in vitro and in vivo models. Pharmacological antagonism and genetic deletion of α4, but not α7, nAChR subunits prevented or significantly attenuated OP-induced electrical spike activity in acute hippocampal slices and seizure activity in mice, indicating that α4 nAChR activation is necessary for neuronal hyperexcitability triggered by acute OP exposures. These findings not only suggest that therapeutic strategies for inhibiting the α4 nAChR subunit warrant further investigation as prophylactic and immediate treatments for acute OP-induced seizures, but also provide mechanistic insight into the role of the nicotinic cholinergic system in seizure generation.
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Affiliation(s)
- Peter M. Andrew
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
| | - Wei Feng
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
| | - Jonas J. Calsbeek
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
| | - Shane P. Antrobus
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
| | - Gennady A. Cherednychenko
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
| | - Jeremy A. MacMahon
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
| | - Pedro N. Bernardino
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
| | - Xiuzhen Liu
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
| | - Danielle J. Harvey
- Department of Public Health Sciences, UC Davis School of Medicine, Davis, CA 95616, USA;
| | - Pamela J. Lein
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
| | - Isaac N. Pessah
- Department of Molecular Biosciences, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA; (P.M.A.); (W.F.); (J.J.C.); (S.P.A.); (G.A.C.); (J.A.M.); (P.N.B.); (X.L.)
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Reddy DS, Singh T, Ramakrishnan S, Huber M, Wu X. Neuroprotectant Activity of Novel Water-Soluble Synthetic Neurosteroids on Organophosphate Intoxication and Status Epilepticus-Induced Long-Term Neurological Dysfunction, Neurodegeneration, and Neuroinflammation. J Pharmacol Exp Ther 2024; 388:399-415. [PMID: 38071567 PMCID: PMC10801736 DOI: 10.1124/jpet.123.001819] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 09/18/2023] [Indexed: 01/19/2024] Open
Abstract
Organophosphates (OPs) and nerve agents are potent neurotoxic compounds that cause seizures, status epilepticus (SE), brain injury, or death. There are persistent long-term neurologic and neurodegenerative effects that manifest months to years after the initial exposure. Current antidotes are ineffective in preventing these long-term neurobehavioral and neuropathological changes. Additionally, there are few effective neuroprotectants for mitigating the long-term effects of acute OP intoxication. We have pioneered neurosteroids as novel anticonvulsants and neuroprotectants for OP intoxication and seizures. In this study, we evaluated the efficacy of two novel synthetic, water-soluble neurosteroids, valaxanolone (VX) and lysaxanolone (LX), in combating the long-term behavioral and neuropathological impairments caused by acute OP intoxication and SE. Animals were exposed to the OP nerve agent surrogate diisopropylfluorophosphate (DFP) and were treated with VX or LX in addition to midazolam at 40 minutes postexposure. The extent of neurodegeneration, along with various behavioral and memory deficits, were assessed at 3 months postexposure. VX significantly reduced deficits of aggressive behavior, anxiety, memory, and depressive-like traits in control (DFP-exposed, midazolam-treated) animals; VX also significantly prevented the DFP-induced chronic loss of NeuN(+) principal neurons and PV(+) inhibitory neurons in the hippocampus and other regions. Additionally, VX-treated animals exhibited a reduced inflammatory response with decreased GFAP(+) astrogliosis and IBA1(+) microgliosis in the hippocampus, amygdala, and other regions. Similarly, LX showed significant improvement in behavioral and memory deficits, and reduced neurodegeneration and cellular neuroinflammation. Together, these results demonstrate the neuroprotectant effects of the novel synthetic neurosteroids in mitigating the long-term neurologic dysfunction and neurodegeneration associated with OP exposure. SIGNIFICANCE STATEMENT: Survivors of nerve agents and organophosphate (OP) exposures suffer from long-term neurological deficits. Currently, there is no specific drug therapy for mitigating the impact of OP exposure. However, novel synthetic neurosteroids that activate tonic inhibition provide a viable option for treating OP intoxication. The data from this study indicates the neuroprotective effects of synthetic, water-soluble neurosteroids for attenuation of long-term neurological deficits after OP intoxication. These findings establish valaxanolone and lysaxanolone as potent and efficacious neuroprotectants suitable for injectable dosing.
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Affiliation(s)
- Doodipala Samba Reddy
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University School of Medicine, Bryan, Texas (D.S.R., T.S., S.R., M.H., X.W.) and Institute of Pharmacology and Neurotherapeutics, Texas A&M University Health Science Center, Bryan, Texas (D.S.R., S.R., X.W.)
| | - Tanveer Singh
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University School of Medicine, Bryan, Texas (D.S.R., T.S., S.R., M.H., X.W.) and Institute of Pharmacology and Neurotherapeutics, Texas A&M University Health Science Center, Bryan, Texas (D.S.R., S.R., X.W.)
| | - Sreevidhya Ramakrishnan
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University School of Medicine, Bryan, Texas (D.S.R., T.S., S.R., M.H., X.W.) and Institute of Pharmacology and Neurotherapeutics, Texas A&M University Health Science Center, Bryan, Texas (D.S.R., S.R., X.W.)
| | - Madeline Huber
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University School of Medicine, Bryan, Texas (D.S.R., T.S., S.R., M.H., X.W.) and Institute of Pharmacology and Neurotherapeutics, Texas A&M University Health Science Center, Bryan, Texas (D.S.R., S.R., X.W.)
| | - Xin Wu
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University School of Medicine, Bryan, Texas (D.S.R., T.S., S.R., M.H., X.W.) and Institute of Pharmacology and Neurotherapeutics, Texas A&M University Health Science Center, Bryan, Texas (D.S.R., S.R., X.W.)
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5
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Liang LP, Pearson-Smith JN, Day BJ, Patel M. Novel Catalytic Antioxidant Formulation Decreases Oxidative Stress, Neuroinflammation and Cognitive Dysfunction in a Model of Nerve Agent Intoxication. J Pharmacol Exp Ther 2024; 388:358-366. [PMID: 37652711 PMCID: PMC10801718 DOI: 10.1124/jpet.123.001708] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 08/15/2023] [Accepted: 08/18/2023] [Indexed: 09/02/2023] Open
Abstract
Reactive oxygen species have an emerging role in the pathologic consequences of status epilepticus. We have previously demonstrated the efficacy of a water-for-injection formulation of the meso-porphyrin catalytic antioxidant, manganese (III) meso-tetrakis (N-N-diethylimidazole) porphyrin (AEOL10150) against oxidative stress, neuroinflammation, and neuronal death initiated by kainic acid, pilocarpine, diisopropylflurophosphate (DFP), and soman. This previous dose and dosing strategy of AEOL10150 required smaller multiple daily injections, precluding our ability to test its efficacy against delayed consequences of nerve agent exposure such as neurodegeneration and cognitive dysfunction. Therefore, we developed formulations of AEOL10150 designed to deliver a larger dose once daily with improved brain pharmacodynamics. We examined four new formulations of AEOL10150 that resulted in 8 times higher subcutaneous dose with lower acute toxicity, slower absorption, longer half-life, and higher maximal plasma concentrations compared with our previous strategy. AEOL10150 brain levels exhibited improved pharmacodynamics over 24 hours with all four formulations. We tested a subcutaneous dose of 40 mg/kg AEOL10150 in two formulations (2% carboxymethyl cellulose and 4% polyethylene glycol-4000) in the DFP rat model, and both formulations exhibited significant protection against DFP-induced oxidative stress. Additionally, and in one formulation (4% polyethylene glycol-4000), AEOL10150 significantly protected against DFP-induced neuronal death, microglial activation, delayed memory impairment, and mortality. These results suggest that reformulation of AEOL10150 can attenuate acute and delayed outcomes of organophosphate neurotoxicity. SIGNIFICANCE STATEMENT: Reformulation of manganese (III) meso-tetrakis (N-N-diethylimidazole) porphyrin allowed higher tolerated doses of the compound with improved pharmacodynamics. Specifically, one new formulation allowed fewer daily doses and improvement in acute and delayed outcomes of organophosphate toxicity.
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Affiliation(s)
- Li-Ping Liang
- Department of Pharmaceutical Sciences, University of Colorado, Anschutz Medical Campus, Aurora, Colorado (L.-P.L., J.N.P.-S., B.J.D., M.P.); and Department of Medicine, National Jewish Health, Denver, Colorado (B.J.D.)
| | - Jennifer N Pearson-Smith
- Department of Pharmaceutical Sciences, University of Colorado, Anschutz Medical Campus, Aurora, Colorado (L.-P.L., J.N.P.-S., B.J.D., M.P.); and Department of Medicine, National Jewish Health, Denver, Colorado (B.J.D.)
| | - Brian J Day
- Department of Pharmaceutical Sciences, University of Colorado, Anschutz Medical Campus, Aurora, Colorado (L.-P.L., J.N.P.-S., B.J.D., M.P.); and Department of Medicine, National Jewish Health, Denver, Colorado (B.J.D.)
| | - Manisha Patel
- Department of Pharmaceutical Sciences, University of Colorado, Anschutz Medical Campus, Aurora, Colorado (L.-P.L., J.N.P.-S., B.J.D., M.P.); and Department of Medicine, National Jewish Health, Denver, Colorado (B.J.D.)
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Ramakrishnan S, Singh T, Reddy DS. Protective Activity of Novel Hydrophilic Synthetic Neurosteroids on Organophosphate Status Epilepticus-induced Chronic Epileptic Seizures, Non-Convulsive Discharges, High-Frequency Oscillations, and Electrographic Ictal Biomarkers. J Pharmacol Exp Ther 2024; 388:386-398. [PMID: 38050069 PMCID: PMC10801763 DOI: 10.1124/jpet.123.001817] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 11/07/2023] [Accepted: 11/08/2023] [Indexed: 12/06/2023] Open
Abstract
Nerve agents and organophosphates (OP) are neurotoxic chemicals that induce acute seizures, status epilepticus (SE), and mortality. Long-term neurologic and neurodegenerative effects manifest months to years after OP exposure. Current benzodiazepine anticonvulsants are ineffective in preventing such long-term neurobehavioral and neuropathological changes. New and effective anticonvulsants are needed for OP intoxication, especially for mitigating the long-term sequelae after acute exposure. We developed neurosteroids as novel anticonvulsants and neuroprotectants in OP exposure models. In this study, we evaluated the long-term efficacy of novel synthetic neurosteroids in preventing the development of chronic epilepsy and hyperexcitable ictal events in a rat OP model of SE. Rats were exposed to the OP nerve agent surrogate diisopropylfluorophosphate (DFP), and the experimental groups were treated with the synthetic neurosteroid valaxanolone (VX) or lysaxanolone (LX) 40 minutes post-exposure in conjunction with midazolam. Video-electroencephalography was monitored for two months to assess spontaneous recurrent seizures (SRS), epileptiform discharges, interictal spikes, and high-frequency oscillations (HFOs). Within 60 days of DFP exposure, rats developed chronic epilepsy characterized by frequent SRS, epileptiform discharges, and HFOs. LX treatment was associated with a dose-dependent reduction of epilepsy occurrence and overall seizure burden with a significant decrease in SRS and epileptiform discharges. It also significantly reduced the occurrence of epileptic biomarkers of HFOs and interictal spikes, indicating potential disease-modifying activity. Similarly, the neurosteroid analog VX also significantly attenuated SRS, discharges, HFOs, and ictal events. These results demonstrate the long-term protective effects of synthetic neurosteroids in the OP-exposed post-SE model, indicating their disease-modifying potential to prevent epilepsy and ictal abnormalities. SIGNIFICANCE STATEMENT: The effects of nerve agents and organophosphate (OP) exposure are persistent, and survivors suffer from a number of devastating, chronic neurological dysfunctions. Currently, there is no specific therapy for preventing this disastrous impact of OP exposure. We propose synthetic neurosteroids that activate tonic inhibition provide viable options for preventing the long-term neurological effects of OP intoxication. The results from this study reveal the disease-modifying potential of two novel synthetic neurosteroids in preventing epileptogenesis and chronic epileptic seizures after OP-induced SE.
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Affiliation(s)
- Sreevidhya Ramakrishnan
- Department of Neuroscience and Experimental Therapeutics (S.R., T.S., D.S.R.) and Institute of Pharmacology and Neurotherapeutics (D.S.R.), School of Medicine, Texas A&M University Health Science Center, Bryan, Texas
| | - Tanveer Singh
- Department of Neuroscience and Experimental Therapeutics (S.R., T.S., D.S.R.) and Institute of Pharmacology and Neurotherapeutics (D.S.R.), School of Medicine, Texas A&M University Health Science Center, Bryan, Texas
| | - Doodipala Samba Reddy
- Department of Neuroscience and Experimental Therapeutics (S.R., T.S., D.S.R.) and Institute of Pharmacology and Neurotherapeutics (D.S.R.), School of Medicine, Texas A&M University Health Science Center, Bryan, Texas
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Blair RE, Hawkins E, Pinchbeck LR, DeLorenzo RJ, Deshpande LS. Chronic Epilepsy and Mossy Fiber Sprouting Following Organophosphate-Induced Status Epilepticus in Rats. J Pharmacol Exp Ther 2024; 388:325-332. [PMID: 37643794 PMCID: PMC10801751 DOI: 10.1124/jpet.123.001739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 07/20/2023] [Accepted: 07/24/2023] [Indexed: 08/31/2023] Open
Abstract
Organophosphate (OP) compounds are highly toxic and include pesticides and chemical warfare nerve agents. OP exposure inhibits the acetylcholinesterase enzyme, causing cholinergic overstimulation that can evolve into status epilepticus (SE) and produce lethality. Furthermore, OP-induced SE survival is associated with mood and memory dysfunction and spontaneous recurrent seizures (SRS). In male Sprague-Dawley rats, we assessed hippocampal pathology and chronic SRS following SE induced by administration of OP agents paraoxon (2 mg/kg, s.c.), diisopropyl fluorophosphate (4 mg/kg, s.c.), or O-isopropyl methylphosphonofluoridate (GB; sarin) (2 mg/kg, s.c.), immediately followed by atropine and 2-PAM. At 1-hour post-OP-induced SE onset, midazolam was administered to control SE. Approximately 6 months after OP-induced SE, SRS were evaluated using video and electroencephalography monitoring. Histopathology was conducted using hematoxylin and eosin (H&E), while silver sulfide (Timm) staining was used to assess mossy fiber sprouting (MFS). Across all the OP agents, over 60% of rats that survived OP-induced SE developed chronic SRS. H&E staining revealed a significant hippocampal neuronal loss, while Timm staining revealed extensive MFS within the inner molecular region of the dentate gyrus. This study demonstrates that OP-induced SE is associated with hippocampal neuronal loss, extensive MFS, and the development of SRS, all hallmarks of chronic epilepsy. SIGNIFICANCE STATEMENT: Models of organophosphate (OP)-induced SE offer a unique resource to identify molecular mechanisms contributing to neuropathology and the development of chronic OP morbidities. These models could allow the screening of targeted therapeutics for efficacious treatment strategies for OP toxicities.
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Affiliation(s)
- Robert E Blair
- Departments of Neurology (R.E.B., E.H., R.J.D., L.S.D.) and Pharmacology and Toxicology (R.J.D., L.S.D.) School of Medicine, and Department of Biology, College of Humanities & Sciences (L.R.P.), Virginia Commonwealth University, Richmond, Virginia
| | - Elisa Hawkins
- Departments of Neurology (R.E.B., E.H., R.J.D., L.S.D.) and Pharmacology and Toxicology (R.J.D., L.S.D.) School of Medicine, and Department of Biology, College of Humanities & Sciences (L.R.P.), Virginia Commonwealth University, Richmond, Virginia
| | - Lauren R Pinchbeck
- Departments of Neurology (R.E.B., E.H., R.J.D., L.S.D.) and Pharmacology and Toxicology (R.J.D., L.S.D.) School of Medicine, and Department of Biology, College of Humanities & Sciences (L.R.P.), Virginia Commonwealth University, Richmond, Virginia
| | - Robert J DeLorenzo
- Departments of Neurology (R.E.B., E.H., R.J.D., L.S.D.) and Pharmacology and Toxicology (R.J.D., L.S.D.) School of Medicine, and Department of Biology, College of Humanities & Sciences (L.R.P.), Virginia Commonwealth University, Richmond, Virginia
| | - Laxmikant S Deshpande
- Departments of Neurology (R.E.B., E.H., R.J.D., L.S.D.) and Pharmacology and Toxicology (R.J.D., L.S.D.) School of Medicine, and Department of Biology, College of Humanities & Sciences (L.R.P.), Virginia Commonwealth University, Richmond, Virginia
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8
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François S, Mondot S, Gerard Q, Bel R, Knoertzer J, Berriche A, Cavallero S, Baati R, Orset C, Dal Bo G, Thibault K. Long-Term Anxiety-Like Behavior and Microbiota Changes Induced in Mice by Sublethal Doses of Acute Sarin Surrogate Exposure. Biomedicines 2022; 10:biomedicines10051167. [PMID: 35625901 PMCID: PMC9138233 DOI: 10.3390/biomedicines10051167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 05/07/2022] [Accepted: 05/16/2022] [Indexed: 12/10/2022] Open
Abstract
Anxiety disorder is one of the most reported complications following organophosphorus (OP) nerve agent (NA) exposure. The goal of this study was to characterize the long-term behavioral impact of a single low dose exposure to 4-nitrophenyl isopropyl methylphosphonate (NIMP), a sarin surrogate. We chose two different sublethal doses of NIMP, each corresponding to a fraction of the median lethal dose (one mild and one convulsive), and evaluated behavioral changes over a 6-month period following exposure. Mice exposed to both doses showed anxious behavior which persisted for six-months post-exposure. A longitudinal magnetic resonance imaging examination did not reveal any anatomical changes in the amygdala throughout the 6-month period. While no cholinesterase activity change or neuroinflammation could be observed at the latest timepoint in the amygdala of NIMP-exposed mice, important modifications in white blood cell counts were noted, reflecting a perturbation of the systemic immune system. Furthermore, intestinal inflammation and microbiota changes were observed at 6-months in NIMP-exposed animals regardless of the dose received. This is the first study to identify long-term behavioral impairment, systemic homeostasis disorganization and gut microbiota alterations following OP sublethal exposure. Our findings highlight the importance of long-term care for victims of NA exposure, even in asymptomatic cases.
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Affiliation(s)
- Sabine François
- Department of Radiation Biological Effects, Armed Forces Biomedical Research Institute, 91220 Bretigny sur Orge, France; (S.F.); (S.C.)
| | - Stanislas Mondot
- Micalis Institute, AgroParisTech, Université Paris-Saclay, INRAE, 78350 Jouy-en-Josas, France;
| | - Quentin Gerard
- Department of Toxicology and Chemical Risks, Armed Forces Biomedical Research Institute, 91220 Bretigny sur Orge, France; (Q.G.); (R.B.); (J.K.); (A.B.)
- Institut Blood and Brain@caen-normandie Cyceron, Caen-Normandie University, UNICAEN, INSERM, UMR-S U1237, Physiopathology and Imaging of Neurological Disorders (PhIND), 14000 Caen, France;
| | - Rosalie Bel
- Department of Toxicology and Chemical Risks, Armed Forces Biomedical Research Institute, 91220 Bretigny sur Orge, France; (Q.G.); (R.B.); (J.K.); (A.B.)
| | - Julie Knoertzer
- Department of Toxicology and Chemical Risks, Armed Forces Biomedical Research Institute, 91220 Bretigny sur Orge, France; (Q.G.); (R.B.); (J.K.); (A.B.)
| | - Asma Berriche
- Department of Toxicology and Chemical Risks, Armed Forces Biomedical Research Institute, 91220 Bretigny sur Orge, France; (Q.G.); (R.B.); (J.K.); (A.B.)
- CEA, 92260 Fontenay aux Roses, France
| | - Sophie Cavallero
- Department of Radiation Biological Effects, Armed Forces Biomedical Research Institute, 91220 Bretigny sur Orge, France; (S.F.); (S.C.)
| | - Rachid Baati
- ICPEES UMR CNRS 7515, Institut de Chimie des Procédés, pour l’Energie, l’Environnement, et la Santé, 67000 Strasbourg, France;
| | - Cyrille Orset
- Institut Blood and Brain@caen-normandie Cyceron, Caen-Normandie University, UNICAEN, INSERM, UMR-S U1237, Physiopathology and Imaging of Neurological Disorders (PhIND), 14000 Caen, France;
| | - Gregory Dal Bo
- Department of Toxicology and Chemical Risks, Armed Forces Biomedical Research Institute, 91220 Bretigny sur Orge, France; (Q.G.); (R.B.); (J.K.); (A.B.)
- Correspondence: (G.D.B.); (K.T.)
| | - Karine Thibault
- Department of Toxicology and Chemical Risks, Armed Forces Biomedical Research Institute, 91220 Bretigny sur Orge, France; (Q.G.); (R.B.); (J.K.); (A.B.)
- Correspondence: (G.D.B.); (K.T.)
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Mundy PC, Mendieta R, Lein PJ. Diisopropylfluorophosphate (DFP) volatizes and cross-contaminates wells in a common 96-well plate format used in zebrafish larvae toxicology studies. J Pharmacol Toxicol Methods 2022; 115:107173. [DOI: 10.1016/j.vascn.2022.107173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 03/23/2022] [Accepted: 05/01/2022] [Indexed: 11/27/2022]
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