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Hobson BA, Rowland DJ, Dou Y, Saito N, Harmany ZT, Bruun DA, Harvey DJ, Chaudhari AJ, Garbow JR, Lein PJ. A longitudinal MRI and TSPO PET-based investigation of brain region-specific neuroprotection by diazepam versus midazolam following organophosphate-induced seizures. Neuropharmacology 2024; 251:109918. [PMID: 38527652 PMCID: PMC11250911 DOI: 10.1016/j.neuropharm.2024.109918] [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: 11/29/2023] [Revised: 03/01/2024] [Accepted: 03/13/2024] [Indexed: 03/27/2024]
Abstract
Acute poisoning with organophosphorus cholinesterase inhibitors (OPs), such as OP nerve agents and pesticides, can cause life threatening cholinergic crisis and status epilepticus (SE). Survivors often experience significant morbidity, including brain injury, acquired epilepsy, and cognitive deficits. Current medical countermeasures for acute OP poisoning include a benzodiazepine to mitigate seizures. Diazepam was long the benzodiazepine included in autoinjectors used to treat OP-induced seizures, but it is now being replaced in many guidelines by midazolam, which terminates seizures more quickly, particularly when administered intramuscularly. While a direct correlation between seizure duration and the extent of brain injury has been widely reported, there are limited data comparing the neuroprotective efficacy of diazepam versus midazolam following acute OP intoxication. To address this data gap, we used non-invasive imaging techniques to longitudinally quantify neuropathology in a rat model of acute intoxication with the OP diisopropylfluorophosphate (DFP) with and without post-exposure intervention with diazepam or midazolam. Magnetic resonance imaging (MRI) was used to monitor neuropathology and brain atrophy, while positron emission tomography (PET) with a radiotracer targeting translocator protein (TSPO) was utilized to assess neuroinflammation. Animals were scanned at 3, 7, 28, 65, 91, and 168 days post-DFP and imaging metrics were quantitated for the hippocampus, amygdala, piriform cortex, thalamus, cerebral cortex and lateral ventricles. In the DFP-intoxicated rat, neuroinflammation persisted for the duration of the study coincident with progressive atrophy and ongoing tissue remodeling. Benzodiazepines attenuated neuropathology in a region-dependent manner, but neither benzodiazepine was effective in attenuating long-term neuroinflammation as detected by TSPO PET. Diffusion MRI and TSPO PET metrics were highly correlated with seizure severity, and early MRI and PET metrics were positively correlated with long-term brain atrophy. Collectively, these results suggest that anti-seizure therapy alone is insufficient to prevent long-lasting neuroinflammation and tissue remodeling.
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Affiliation(s)
- Brad A Hobson
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616, USA; Center for Molecular and Genomic Imaging, University of California, Davis, College of Engineering, Davis, CA 95616, USA.
| | - Douglas J Rowland
- Center for Molecular and Genomic Imaging, University of California, Davis, College of Engineering, Davis, CA 95616, USA.
| | - Yimeng Dou
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616, USA.
| | - Naomi Saito
- Department of Public Health Sciences, University of California, Davis, School of Medicine, California 95616, USA.
| | - Zachary T Harmany
- Center for Molecular and Genomic Imaging, University of California, Davis, College of Engineering, Davis, CA 95616, USA.
| | - Donald A Bruun
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616, USA.
| | - Danielle J Harvey
- Department of Public Health Sciences, University of California, Davis, School of Medicine, California 95616, USA.
| | - Abhijit J Chaudhari
- Center for Molecular and Genomic Imaging, University of California, Davis, College of Engineering, Davis, CA 95616, USA; Department of Radiology, University of California, Davis, School of Medicine, California 95817, USA.
| | - Joel R Garbow
- Biomedical Magnetic Resonance Center, Mallinckrodt Institute of Radiology, School of Medicine, Washington University in St. Louis, St. Louis, Missouri, 63110, USA.
| | - Pamela J Lein
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616, USA.
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2
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Almeida AJD, Hobson BA, Saito N, Bruun DA, Porter VA, Harvey DJ, Garbow JR, Chaudhari AJ, Lein PJ. Quantitative T 2 mapping-based longitudinal assessment of brain injury and therapeutic rescue in the rat following acute organophosphate intoxication. Neuropharmacology 2024; 249:109895. [PMID: 38437913 PMCID: PMC11227117 DOI: 10.1016/j.neuropharm.2024.109895] [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: 09/08/2023] [Revised: 02/07/2024] [Accepted: 02/29/2024] [Indexed: 03/06/2024]
Abstract
Acute intoxication with organophosphate (OP) cholinesterase inhibitors poses a significant public health risk. While currently approved medical countermeasures can improve survival rates, they often fail to prevent chronic neurological damage. Therefore, there is need to develop effective therapies and quantitative metrics for assessing OP-induced brain injury and its rescue by these therapies. In this study we used a rat model of acute intoxication with the OP, diisopropylfluorophosphate (DFP), to test the hypothesis that T2 measures obtained from brain magnetic resonance imaging (MRI) scans provide quantitative metrics of brain injury and therapeutic efficacy. Adult male Sprague Dawley rats were imaged on a 7T MRI scanner at 3, 7 and 28 days post-exposure to DFP or vehicle (VEH) with or without treatment with the standard of care antiseizure drug, midazolam (MDZ); a novel antiseizure medication, allopregnanolone (ALLO); or combination therapy with MDZ and ALLO (DUO). Our results show that mean T2 values in DFP-exposed animals were: (1) higher than VEH in all volumes of interest (VOIs) at day 3; (2) decreased with time; and (3) decreased in the thalamus at day 28. Treatment with ALLO or DUO, but not MDZ alone, significantly decreased mean T2 values relative to untreated DFP animals in the piriform cortex at day 3. On day 28, the DUO group showed the most favorable T2 characteristics. This study supports the utility of T2 mapping for longitudinally monitoring brain injury and highlights the therapeutic potential of ALLO as an adjunct therapy to mitigate chronic morbidity associated with acute OP intoxication.
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Affiliation(s)
- Alita Jesal D Almeida
- Department of Biomedical Engineering, University of California-Davis College of Engineering, Davis, CA, 95616, USA; Department of Radiology, University of California-Davis School of Medicine, Sacramento, CA, 95817, USA.
| | - Brad A Hobson
- Center for Molecular and Genomic Imaging, Department of Biomedical Engineering, University of California-Davis College of Engineering, Davis, CA, 95616, USA.
| | - Naomi Saito
- Department of Public Health Sciences, University of California-Davis School of Medicine, Davis, CA, 95616, USA
| | - Donald A Bruun
- Department of Molecular Biosciences, University of California-Davis School of Veterinary Medicine, Davis, CA, 95616, USA.
| | - Valerie A Porter
- Department of Biomedical Engineering, University of California-Davis College of Engineering, Davis, CA, 95616, USA; Department of Radiology, University of California-Davis School of Medicine, Sacramento, CA, 95817, USA.
| | - Danielle J Harvey
- Department of Public Health Sciences, University of California-Davis School of Medicine, Davis, CA, 95616, USA.
| | - Joel R Garbow
- Department of Radiology, Washington University School of Medicine, St Louis, MO, 63110, USA.
| | - Abhijit J Chaudhari
- Department of Radiology, University of California-Davis School of Medicine, Sacramento, CA, 95817, USA; Center for Molecular and Genomic Imaging, Department of Biomedical Engineering, University of California-Davis College of Engineering, Davis, CA, 95616, USA.
| | - Pamela J Lein
- Department of Molecular Biosciences, University of California-Davis School of Veterinary Medicine, Davis, CA, 95616, USA.
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3
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Singh T, Ramakrishnan S, Wu X, Reddy DS. Sex Differences in Organophosphate Model of Benzodiazepine-Refractory Status Epilepticus and Neuronal Damage. J Pharmacol Exp Ther 2024; 388:313-324. [PMID: 37770202 PMCID: PMC10801723 DOI: 10.1124/jpet.123.001747] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 08/15/2023] [Accepted: 08/17/2023] [Indexed: 10/03/2023] Open
Abstract
Sex differences are common in human epilepsy. Although men are more susceptible to seizure than women, the mechanisms underlying sex-specific vulnerabilities to seizure are unclear. The organophosphate (OP) diisopropylfluorophosphate (DFP) is known to cause neurotoxicity and status epilepticus (SE), a serious neurologic condition that causes prolonged seizures and brain damage. Current therapies for OP poisoning and SE do not consider neuronal variations between male and female brains. Therefore, we investigated sex-dependent differences in electrographic seizure activity and neuronal injury using the DFP model of refractory SE in rats. Electroencephalogram recordings were used to monitor DFP-induced SE, and the extent of brain injury was determined using fluoro-jade-B staining to detect cellular necrosis. After DFP exposure, we observed striking sex-dependent differences in SE and seizure activity patterns as well as protective responses to midazolam treatment. Following acute DFP exposure, male animals displayed more severe SE with intense epileptiform spiking and greater mortality than females. In contrast, we observed significantly more injured cells and cellular necrosis in the hippocampus and other brain regions in females than in males. We also observed extensive neuronal injury in the somatosensory cortex of males. The anticonvulsant effect of midazolam against SE was limited in this model and found to be similar in males and females. However, unlike males, females exhibited substantially more protection against neuronal damage after midazolam treatment. Overall, these results demonstrate significant sex-dependent differences in DFP-induced refractory SE and neuronal damage patterns, suggesting that it may be possible to develop sex-specific neuroprotective strategies for OP intoxication and refractory SE. SIGNIFICANCE STATEMENT: Sex-dependent differences in neurotoxicity and status epilepticus (SE) are key biological variables after organophosphate (OP) exposure. Here, we investigated sex-dependent differences in SE and brain injury after acute diisopropylfluorophosphate exposure. Male rats had more severe SE and less survival than females, while females had more neuronal damage. Females had more neuroprotection to midazolam than males, while both sexes had similar but partial anticonvulsant effects. These findings suggest that a sex-specific therapeutic approach may prevent neurological complications of OP-induced SE.
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Affiliation(s)
- Tanveer Singh
- Department of Neuroscience and Experimental Therapeutics and Institute of Pharmacology and Neurotherapeutics, Texas A&M University School of Medicine, Bryan, Texas
| | - Sreevidhya Ramakrishnan
- Department of Neuroscience and Experimental Therapeutics and Institute of Pharmacology and Neurotherapeutics, Texas A&M University School of Medicine, Bryan, Texas
| | - Xin Wu
- Department of Neuroscience and Experimental Therapeutics and Institute of Pharmacology and Neurotherapeutics, Texas A&M University School of Medicine, Bryan, Texas
| | - Doodipala Samba Reddy
- Department of Neuroscience and Experimental Therapeutics and Institute of Pharmacology and Neurotherapeutics, Texas A&M University School of Medicine, Bryan, Texas
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4
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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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5
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Bernardino PN, Hobson BA, Huddleston SL, Andrew PM, MacMahon JA, Saito NH, Porter VA, Bruun DA, Harvey DJ, Garbow JR, Gelli A, Chaudhari AJ, Lein PJ. Time- and region-dependent blood-brain barrier impairment in a rat model of organophosphate-induced status epilepticus. Neurobiol Dis 2023; 187:106316. [PMID: 37797902 PMCID: PMC11000668 DOI: 10.1016/j.nbd.2023.106316] [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: 05/02/2023] [Revised: 09/26/2023] [Accepted: 10/02/2023] [Indexed: 10/07/2023] Open
Abstract
Acute organophosphate (OP) intoxication can trigger seizures that progress to status epilepticus (SE), and survivors often develop chronic morbidities, including spontaneous recurrent seizures (SRS). The pathogenic mechanisms underlying OP-induced SRS are unknown, but increased BBB permeability is hypothesized to be involved. Previous studies reported BBB leakage following OP-induced SE, but key information regarding time and regional distribution of BBB impairment during the epileptogenic period is missing. To address this data gap, we characterized the spatiotemporal progression of BBB impairment during the first week post-exposure in a rat model of diisopropylfluorophosphate-induced SE, using MRI and albumin immunohistochemistry. Increased BBB permeability, which was detected at 6 h and persisted up to 7 d post-exposure, was most severe and persistent in the piriform cortex and amygdala, moderate but persistent in the thalamus, and less severe and transient in the hippocampus and somatosensory cortex. The extent of BBB leakage was positively correlated with behavioral seizure severity, with the strongest association identified in the piriform cortex and amygdala. These findings provide evidence of the duration, magnitude and spatial breakdown of the BBB during the epileptogenic period following OP-induced SE and support BBB regulation as a viable therapeutic target for preventing SRS following acute OP intoxication.
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Affiliation(s)
- Pedro N Bernardino
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616, USA.
| | - Brad A Hobson
- Center for Molecular and Genomic Imaging, University of California, Davis, Davis, CA 95616, USA.
| | - Sydney L Huddleston
- Center for Molecular and Genomic Imaging, University of California, Davis, Davis, CA 95616, USA.
| | - Peter M Andrew
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616, USA.
| | - Jeremy A MacMahon
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616, USA.
| | - Naomi H Saito
- Department of Public Health Sciences, University of California, Davis, School of Medicine, Davis, CA 95616, USA.
| | - Valerie A Porter
- Department of Biomedical Engineering, University of California, Davis, College of Engineering, Davis, CA 95616, USA.
| | - Donald A Bruun
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616, USA.
| | - Danielle J Harvey
- Department of Public Health Sciences, University of California, Davis, School of Medicine, Davis, CA 95616, USA.
| | - Joel R Garbow
- Biomedical Magnetic Resonance Center, Mallinckrodt Institute of Radiology, School of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA.
| | - Angie Gelli
- Department of Pharmacology, University of California, Davis, School of Medicine, Davis, CA 95616, USA.
| | - Abhijit J Chaudhari
- Center for Molecular and Genomic Imaging, University of California, Davis, Davis, CA 95616, USA; Department of Radiology, University of California, Davis, School of Medicine, Sacramento, CA 95817, USA.
| | - Pamela J Lein
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616, USA.
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6
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Piel S, Janowska JI, Ward JL, McManus MJ, Jose JS, Starr J, Sheldon M, Clayman CL, Elmér E, Hansson MJ, Jang DH, Karlsson M, Ehinger JK, Kilbaugh TJ. Succinate prodrugs in combination with atropine and pralidoxime protect cerebral mitochondrial function in a rodent model of acute organophosphate poisoning. Sci Rep 2022; 12:20329. [PMID: 36434021 PMCID: PMC9700731 DOI: 10.1038/s41598-022-24472-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 11/15/2022] [Indexed: 11/27/2022] Open
Abstract
Pesticides account for hundreds of millions of cases of acute poisoning worldwide each year, with organophosphates (OPs) being responsible for the majority of all pesticide-related deaths. OPs inhibit the enzyme acetylcholinesterase (AChE), which leads to impairment of the central- and peripheral nervous system. Current standard of care (SOC) alleviates acute neurologic-, cardiovascular- and respiratory symptoms and reduces short term mortality. However, survivors often demonstrate significant neurologic sequelae. This highlights the critical need for further development of adjunctive therapies with novel targets. While the inhibition of AChE is thought to be the main mechanism of injury, mitochondrial dysfunction and resulting metabolic crisis may contribute to the overall toxicity of these agents. We hypothesized that the mitochondrially targeted succinate prodrug NV354 would support mitochondrial function and reduce brain injury during acute intoxication with the OP diisopropylfluorophosphate (DFP). To this end, we developed a rat model of acute DFP intoxication and evaluated the efficacy of NV354 as adjunctive therapy to SOC treatment with atropine and pralidoxime. We demonstrate that NV354, in combination with atropine and pralidoxime therapy, significantly improved cerebral mitochondrial complex IV-linked respiration and reduced signs of brain injury in a rodent model of acute DFP exposure.
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Affiliation(s)
- Sarah Piel
- grid.239552.a0000 0001 0680 8770Resuscitation Science Center of Emphasis, The Children’s Hospital of Philadelphia, 3401 Civic Center Boulevard, Philadelphia, PA 19104 USA ,grid.239552.a0000 0001 0680 8770Anesthesiology and Critical Care Medicine, The Children’s Hospital of Philadelphia, Philadelphia, USA
| | - Joanna I. Janowska
- grid.239552.a0000 0001 0680 8770Resuscitation Science Center of Emphasis, The Children’s Hospital of Philadelphia, 3401 Civic Center Boulevard, Philadelphia, PA 19104 USA ,grid.239552.a0000 0001 0680 8770Anesthesiology and Critical Care Medicine, The Children’s Hospital of Philadelphia, Philadelphia, USA
| | - J. Laurenson Ward
- grid.239552.a0000 0001 0680 8770Resuscitation Science Center of Emphasis, The Children’s Hospital of Philadelphia, 3401 Civic Center Boulevard, Philadelphia, PA 19104 USA ,grid.239552.a0000 0001 0680 8770Anesthesiology and Critical Care Medicine, The Children’s Hospital of Philadelphia, Philadelphia, USA
| | - Meagan J. McManus
- grid.239552.a0000 0001 0680 8770Resuscitation Science Center of Emphasis, The Children’s Hospital of Philadelphia, 3401 Civic Center Boulevard, Philadelphia, PA 19104 USA ,grid.239552.a0000 0001 0680 8770Anesthesiology and Critical Care Medicine, The Children’s Hospital of Philadelphia, Philadelphia, USA
| | - Joshua S. Jose
- grid.239552.a0000 0001 0680 8770Resuscitation Science Center of Emphasis, The Children’s Hospital of Philadelphia, 3401 Civic Center Boulevard, Philadelphia, PA 19104 USA ,grid.239552.a0000 0001 0680 8770Anesthesiology and Critical Care Medicine, The Children’s Hospital of Philadelphia, Philadelphia, USA
| | - Jonathan Starr
- grid.239552.a0000 0001 0680 8770Resuscitation Science Center of Emphasis, The Children’s Hospital of Philadelphia, 3401 Civic Center Boulevard, Philadelphia, PA 19104 USA ,grid.239552.a0000 0001 0680 8770Anesthesiology and Critical Care Medicine, The Children’s Hospital of Philadelphia, Philadelphia, USA
| | - Malkah Sheldon
- grid.239552.a0000 0001 0680 8770Resuscitation Science Center of Emphasis, The Children’s Hospital of Philadelphia, 3401 Civic Center Boulevard, Philadelphia, PA 19104 USA ,grid.239552.a0000 0001 0680 8770Anesthesiology and Critical Care Medicine, The Children’s Hospital of Philadelphia, Philadelphia, USA
| | - Carly L. Clayman
- grid.239552.a0000 0001 0680 8770Resuscitation Science Center of Emphasis, The Children’s Hospital of Philadelphia, 3401 Civic Center Boulevard, Philadelphia, PA 19104 USA ,grid.239552.a0000 0001 0680 8770Anesthesiology and Critical Care Medicine, The Children’s Hospital of Philadelphia, Philadelphia, USA
| | - Eskil Elmér
- grid.4514.40000 0001 0930 2361Mitochondrial Medicine, Department of Clinical Sciences Lund, Lund University, Lund, Sweden ,Abliva AB, Lund, Sweden
| | - Magnus J. Hansson
- grid.4514.40000 0001 0930 2361Mitochondrial Medicine, Department of Clinical Sciences Lund, Lund University, Lund, Sweden ,Abliva AB, Lund, Sweden
| | - David H. Jang
- grid.25879.310000 0004 1936 8972Division of Medical Toxicology, Department of Emergency Medicine, University of Pennsylvania School of Medicine, Philadelphia, USA
| | - Michael Karlsson
- grid.475435.4Department of Neurosurgery, Rigshospitalet, Copenhagen, Denmark
| | - Johannes K. Ehinger
- grid.4514.40000 0001 0930 2361Mitochondrial Medicine, Department of Clinical Sciences Lund, Lund University, Lund, Sweden ,grid.4514.40000 0001 0930 2361Otorhinolaryngology, Head and Neck Surgery, Department of Clinical Sciences Lund, Lund University, Skåne University Hospital, Lund, Sweden
| | - Todd J. Kilbaugh
- grid.239552.a0000 0001 0680 8770Resuscitation Science Center of Emphasis, The Children’s Hospital of Philadelphia, 3401 Civic Center Boulevard, Philadelphia, PA 19104 USA ,grid.239552.a0000 0001 0680 8770Anesthesiology and Critical Care Medicine, The Children’s Hospital of Philadelphia, Philadelphia, USA
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7
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Wei B, Liu W, Jin L, Guo S, Fan H, Jin F, Wei C, Fang D, Zhang X, Su S, Duan C, Li X. Dexmedetomidine Inhibits Gasdermin D-Induced Pyroptosis via the PI3K/AKT/GSK3β Pathway to Attenuate Neuroinflammation in Early Brain Injury After Subarachnoid Hemorrhage in Rats. Front Cell Neurosci 2022; 16:899484. [PMID: 35800132 PMCID: PMC9253293 DOI: 10.3389/fncel.2022.899484] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 05/19/2022] [Indexed: 11/18/2022] Open
Abstract
Subarachnoid hemorrhage (SAH) is one kind of life-threatening stroke, which leads to severe brain damage. Pyroptosis plays a critical role in early brain injury (EBI) after SAH. Previous reports suggest that SAH-induced brain edema, cell apoptosis, and neuronal injury could be suppressed by dexmedetomidine (Dex). In this study, we used a rat model of SAH to investigate the effect of Dex on pyroptosis in EBI after SAH and to determine the mechanisms involved. Pyroptosis was found in microglia in EBI after SAH. Dex significantly alleviated microglia pyroptosis via reducing pyroptosis executioner GSDMD and inhibited the release of proinflammatory cytokines induced by SAH. Furthermore, the reduction of GSDMD by Dex was abolished by the PI3K inhibitor LY294002. In conclusion, our data demonstrated that Dex reduces microglia pyroptosis in EBI after SAH via the activation of the PI3K/AKT/GSK3β pathway.
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Affiliation(s)
- Boyang Wei
- Neurosurgery Center, Department of Cerebrovascular Surgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China on Diagnosis and Treatment of Cerebrovascular Disease, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Wenchao Liu
- Neurosurgery Center, Department of Cerebrovascular Surgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China on Diagnosis and Treatment of Cerebrovascular Disease, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Lei Jin
- Neurosurgery Center, Department of Cerebrovascular Surgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China on Diagnosis and Treatment of Cerebrovascular Disease, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Shenquan Guo
- Neurosurgery Center, Department of Cerebrovascular Surgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China on Diagnosis and Treatment of Cerebrovascular Disease, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Haiyan Fan
- Neurosurgery Center, Department of Cerebrovascular Surgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China on Diagnosis and Treatment of Cerebrovascular Disease, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Fa Jin
- Neurosurgery Center, Department of Cerebrovascular Surgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China on Diagnosis and Treatment of Cerebrovascular Disease, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Chengcong Wei
- Neurosurgery Center, Department of Cerebrovascular Surgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China on Diagnosis and Treatment of Cerebrovascular Disease, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Dazhao Fang
- Neurosurgery Center, Department of Cerebrovascular Surgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China on Diagnosis and Treatment of Cerebrovascular Disease, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Xin Zhang
- Neurosurgery Center, Department of Cerebrovascular Surgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China on Diagnosis and Treatment of Cerebrovascular Disease, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Shixing Su
- Neurosurgery Center, Department of Cerebrovascular Surgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China on Diagnosis and Treatment of Cerebrovascular Disease, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Chuanzhi Duan
- Neurosurgery Center, Department of Cerebrovascular Surgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China on Diagnosis and Treatment of Cerebrovascular Disease, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Xifeng Li
- Neurosurgery Center, Department of Cerebrovascular Surgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China on Diagnosis and Treatment of Cerebrovascular Disease, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, Guangzhou, China
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8
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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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9
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Time-dependent neuropathology in rats following organophosphate-induced status epilepticus. Neurotoxicology 2022; 91:45-59. [DOI: 10.1016/j.neuro.2022.04.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 04/11/2022] [Accepted: 04/24/2022] [Indexed: 11/17/2022]
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10
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Gage M, Putra M, Gomez-Estrada C, Golden M, Wachter L, Gard M, Thippeswamy T. Differential Impact of Severity and Duration of Status Epilepticus, Medical Countermeasures, and a Disease-Modifier, Saracatinib, on Brain Regions in the Rat Diisopropylfluorophosphate Model. Front Cell Neurosci 2021; 15:772868. [PMID: 34720886 PMCID: PMC8555467 DOI: 10.3389/fncel.2021.772868] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 09/28/2021] [Indexed: 11/29/2022] Open
Abstract
Acute organophosphate (OP) toxicity poses a significant threat to both military and civilian personnel as it can lead to a variety of cholinergic symptoms including the development of status epilepticus (SE). Depending on its severity, SE can lead to a spectrum of neurological changes including neuroinflammation and neurodegeneration. In this study, we determined the impact of SE severity and duration on disease promoting parameters such as gliosis and neurodegeneration and the efficacy of a disease modifier, saracatinib (AZD0530), a Src/Fyn tyrosine kinase inhibitor. Animals were exposed to 4 mg/kg diisopropylfluorophosphate (DFP, s.c.) followed by medical countermeasures. We had five experimental groups: controls (no DFP), animals with no continuous convulsive seizures (CS), animals with ∼20-min continuous CS, 31-60-min continuous CS, and > 60-min continuous CS. These groups were then assessed for astrogliosis, microgliosis, and neurodegeneration 8 days after DFP exposure. The 31-60-min and > 60-min groups, but not ∼20-min group, had significantly upregulated gliosis and neurodegeneration in the hippocampus compared to controls. In the piriform cortex and amygdala, however, all three continuous CS groups had significant upregulation in both gliosis and neurodegeneration. In a separate cohort of animals that had ∼20 and > 60-min of continuous CS, we administered saracatinib for 7 days beginning three hours after DFP. There was bodyweight loss and mortality irrespective of the initial SE severity and duration. However, in survived animals, saracatinib prevented spontaneous recurrent seizures (SRS) during the first week in both severity groups. In the ∼20-min CS group, compared to the vehicle, saracatinib significantly reduced neurodegeneration in the piriform cortex and amygdala. There were no significant differences in the measured parameters between the naïve control and saracatinib on its own (without DFP) groups. Overall, this study demonstrates the differential effects of the initial SE severity and duration on the localization of gliosis and neurodegeneration. We have also demonstrated the disease-modifying potential of saracatinib. However, its’ dosing regimen should be optimized based on initial severity and duration of CS during SE to maximize therapeutic effects and minimize toxicity in the DFP model as well as in other OP models such as soman.
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Affiliation(s)
- Meghan Gage
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States.,Neuroscience Interdepartmental Program, Iowa State University, Ames, IA, United States
| | - Marson Putra
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States.,Neuroscience Interdepartmental Program, Iowa State University, Ames, IA, United States
| | - Crystal Gomez-Estrada
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Madison Golden
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Logan Wachter
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Megan Gard
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Thimmasettappa Thippeswamy
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States.,Neuroscience Interdepartmental Program, Iowa State University, Ames, IA, United States
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11
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González EA, Calsbeek JJ, Tsai YH, Tang MY, Andrew P, Vu J, Berg EL, Saito NH, Harvey DJ, Supasai S, Gurkoff GG, Silverman JL, Lein PJ. Sex-specific acute and chronic neurotoxicity of acute diisopropylfluorophosphate (DFP)-intoxication in juvenile Sprague-Dawley rats. Curr Res Toxicol 2021; 2:341-356. [PMID: 34622217 PMCID: PMC8484742 DOI: 10.1016/j.crtox.2021.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/06/2021] [Accepted: 09/09/2021] [Indexed: 12/12/2022] Open
Abstract
Preclinical efforts to improve medical countermeasures against organophosphate (OP) chemical threat agents have largely focused on adult male models. However, age and sex have been shown to influence the neurotoxicity of repeated low-level OP exposure. Therefore, to determine the influence of sex and age on outcomes associated with acute OP intoxication, postnatal day 28 Sprague-Dawley male and female rats were exposed to the OP diisopropylfluorophosphate (DFP; 3.4 mg/kg, s.c.) or an equal volume of vehicle (∼80 µL saline, s.c.) followed by atropine sulfate (0.1 mg/kg, i.m.) and pralidoxime (2-PAM; 25 mg/kg, i.m.). Seizure activity was assessed during the first 4 h post-exposure using behavioral criteria and electroencephalographic (EEG) recordings. At 1 d post-exposure, acetylcholinesterase (AChE) activity was measured in cortical tissue, and at 1, 7, and 28 d post-exposure, brains were collected for neuropathologic analyses. At 1 month post-DFP, animals were analyzed for motor ability, learning and memory, and hippocampal neurogenesis. Acute DFP intoxication triggered more severe seizure behavior in males than females, which was supported by EEG recordings. DFP caused significant neurodegeneration and persistent microglial activation in numerous brain regions of both sexes, but astrogliosis occurred earlier and was more severe in males compared to females. DFP males and females exhibited pronounced memory deficits relative to sex-matched controls. In contrast, acute DFP intoxication altered hippocampal neurogenesis in males, but not females. These findings demonstrate that acute DFP intoxication triggers seizures in juvenile rats of both sexes, but the seizure severity varies by sex. Some, but not all, chronic neurotoxic outcomes also varied by sex. The spatiotemporal patterns of neurological damage suggest that microglial activation may be a more important factor than astrogliosis or altered neurogenesis in the pathogenesis of cognitive deficits in juvenile rats acutely intoxicated with OPs.
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Key Words
- 2-PAM, pralidoxime
- AChE, acetylcholinesterase
- AS, atropine-sulfate
- BChE, butyrylcholinesterase
- CT, computed tomography
- ChE, cholinesterase
- Cognitive deficits
- DFP, diisopropylfluorophosphate
- EEG, electroencephalogram
- FJC, Fluoro-Jade C
- Neurodegeneration
- Neurogenesis
- Neuroinflammation
- OP, organophosphate
- PBS, phosphate-buffered saline
- ROI, region of interest
- SE, status epilepticus
- Seizures
- Sex differences
- T2w, T2-weighted
- VEH, vehicle
- i.m., intramuscular
- i.p., intraperitoneal
- s.c., subcutaneous
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Affiliation(s)
- Eduardo A. González
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, 1089 Veterinary Medicine Drive, Davis, CA 95616, USA
| | - Jonas J. Calsbeek
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, 1089 Veterinary Medicine Drive, Davis, CA 95616, USA
| | - Yi-Hua Tsai
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, 1089 Veterinary Medicine Drive, Davis, CA 95616, USA
| | - Mei-Yun Tang
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, 1089 Veterinary Medicine Drive, Davis, CA 95616, USA
| | - Peter Andrew
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, 1089 Veterinary Medicine Drive, Davis, CA 95616, USA
| | - Joan Vu
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, 1089 Veterinary Medicine Drive, Davis, CA 95616, USA
| | - Elizabeth L. Berg
- Department of Psychiatry, University of California, Davis, School of Medicine, 2230, Stockton Boulevard, Sacramento, CA 95817, USA
| | - Naomi H. Saito
- Department of Public Health Sciences, University of California, Davis, One Shields Avenue, School of Medicine, Davis, CA 95616, USA
| | - Danielle J. Harvey
- Department of Public Health Sciences, University of California, Davis, One Shields Avenue, School of Medicine, Davis, CA 95616, USA
| | - Suangsuda Supasai
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, 1089 Veterinary Medicine Drive, Davis, CA 95616, USA
| | - Gene G. Gurkoff
- Department of Neurological Surgery, University of California, Davis, School of Medicine, 4860 Y Street, Sacramento, CA 95817, USA
- Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, CA 95618, USA
| | - Jill L. Silverman
- Department of Psychiatry, University of California, Davis, School of Medicine, 2230, Stockton Boulevard, Sacramento, CA 95817, USA
- MIND Institute, University of California, Davis, 2825 50th Street, Sacramento, CA 95817, USA
| | - Pamela J. Lein
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, 1089 Veterinary Medicine Drive, Davis, CA 95616, USA
- MIND Institute, University of California, Davis, 2825 50th Street, Sacramento, CA 95817, USA
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12
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Calsbeek JJ, González EA, Bruun DA, Guignet MA, Copping N, Dawson ME, Yu AJ, MacMahon JA, Saito NH, Harvey DJ, Silverman JL, Lein PJ. Persistent neuropathology and behavioral deficits in a mouse model of status epilepticus induced by acute intoxication with diisopropylfluorophosphate. Neurotoxicology 2021; 87:106-119. [PMID: 34509511 PMCID: PMC8595753 DOI: 10.1016/j.neuro.2021.09.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 08/27/2021] [Accepted: 09/06/2021] [Indexed: 01/01/2023]
Abstract
Organophosphate (OP) nerve agents and pesticides are a class of neurotoxic compounds that can cause status epilepticus (SE), and death following acute high-dose exposures. While the standard of care for acute OP intoxication (atropine, oxime, and high-dose benzodiazepine) can prevent mortality, survivors of OP poisoning often experience long-term brain damage and cognitive deficits. Preclinical studies of acute OP intoxication have primarily used rat models to identify candidate medical countermeasures. However, the mouse offers the advantage of readily available knockout strains for mechanistic studies of acute and chronic consequences of OP-induced SE. Therefore, the main objective of this study was to determine whether a mouse model of acute diisopropylfluorophosphate (DFP) intoxication would produce acute and chronic neurotoxicity similar to that observed in rat models and humans following acute OP intoxication. Adult male C57BL/6J mice injected with DFP (9.5 mg/kg, s.c.) followed 1 min later with atropine sulfate (0.1 mg/kg, i.m.) and 2-pralidoxime (25 mg/kg, i.m.) developed behavioral and electrographic signs of SE within minutes that continued for at least 4 h. Acetylcholinesterase inhibition persisted for at least 3 d in the blood and 14 d in the brain of DFP mice relative to vehicle (VEH) controls. Immunohistochemical analyses revealed significant neurodegeneration and neuroinflammation in multiple brain regions at 1, 7, and 28 d post-exposure in the brains of DFP mice relative to VEH controls. Deficits in locomotor and home-cage behavior were observed in DFP mice at 28 d post-exposure. These findings demonstrate that this mouse model replicates many of the outcomes observed in rats and humans acutely intoxicated with OPs, suggesting the feasibility of using this model for mechanistic studies and therapeutic screening.
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Affiliation(s)
- Jonas J Calsbeek
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA, 95616, USA.
| | - Eduardo A González
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA, 95616, USA.
| | - Donald A Bruun
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA, 95616, USA.
| | - Michelle A Guignet
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA, 95616, USA.
| | - Nycole Copping
- Department of Psychiatry and Behavioral Sciences, School of Medicine, University of California, Davis, Sacramento, CA, 95817, USA; MIND Institute, School of Medicine, University of California, Davis, Sacramento, CA, 95817, USA.
| | - Mallory E Dawson
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA, 95616, USA.
| | - Alexandria J Yu
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA, 95616, USA.
| | - Jeremy A MacMahon
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA, 95616, USA.
| | - Naomi H Saito
- Department of Public Health Sciences, University of California, Davis, School of Medicine, Davis, CA, 95616, USA.
| | - Danielle J Harvey
- Department of Public Health Sciences, University of California, Davis, School of Medicine, Davis, CA, 95616, USA.
| | - Jill L Silverman
- Department of Psychiatry and Behavioral Sciences, School of Medicine, University of California, Davis, Sacramento, CA, 95817, USA; MIND Institute, School of Medicine, University of California, Davis, Sacramento, CA, 95817, USA.
| | - Pamela J Lein
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA, 95616, USA; MIND Institute, School of Medicine, University of California, Davis, Sacramento, CA, 95817, USA.
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13
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Abstract
The canonical mechanism of organophosphate (OP) neurotoxicity is the inhibition of acetylcholinesterase (AChE). However, multiple lines of evidence suggest that mechanisms in addition to or other than AChE inhibition contribute to the neurotoxic effects associated with acute and chronic OP exposures. Characterizing the role(s) of AChE inhibition versus noncholinergic mechanisms in OP neurotoxicity remains an active area of research with significant diagnostic and therapeutic implications. Here, we review recently published studies that provide mechanistic insights regarding (1) OP-induced status epilepticus, (2) long-term neurologic consequences of acute OP exposures, and (3) neurotoxic effects associated with repeated low-level OP exposures. Key data gaps and challenges are also discussed.
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Affiliation(s)
- Yi-Hua Tsai
- Department of Molecular Sciences, University of California, Davis School of Veterinary Medicine, 1089 Veterinary Medicine Drive, Davis, CA, 95616, USA
| | - Pamela J Lein
- Department of Molecular Sciences, University of California, Davis School of Veterinary Medicine, 1089 Veterinary Medicine Drive, Davis, CA, 95616, USA
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14
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Andrew PM, Lein PJ. Neuroinflammation as a Therapeutic Target for Mitigating the Long-Term Consequences of Acute Organophosphate Intoxication. Front Pharmacol 2021; 12:674325. [PMID: 34054549 PMCID: PMC8153682 DOI: 10.3389/fphar.2021.674325] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 04/30/2021] [Indexed: 12/14/2022] Open
Abstract
Acute intoxication with organophosphates (OPs) can cause a potentially fatal cholinergic crisis characterized by peripheral parasympathomimetic symptoms and seizures that rapidly progress to status epilepticus (SE). While current therapeutic countermeasures for acute OP intoxication significantly improve the chances of survival when administered promptly, they are insufficient for protecting individuals from chronic neurologic outcomes such as cognitive deficits, affective disorders, and acquired epilepsy. Neuroinflammation is posited to contribute to the pathogenesis of these long-term neurologic sequelae. In this review, we summarize what is currently known regarding the progression of neuroinflammatory responses after acute OP intoxication, drawing parallels to other models of SE. We also discuss studies in which neuroinflammation was targeted following OP-induced SE, and explain possible reasons why such therapeutic interventions have inconsistently and only partially improved long-term outcomes. Finally, we suggest future directions for the development of therapeutic strategies that target neuroinflammation to mitigate the neurologic sequelae of acute OP intoxication.
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Affiliation(s)
| | - Pamela J. Lein
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, United States
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15
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Angrand L, Takillah S, Malissin I, Berriche A, Cervera C, Bel R, Gerard Q, Knoertzer J, Baati R, Kononchik JP, Megarbane B, Thibault K, Dal Bo G. Persistent brainwave disruption and cognitive impairment induced by acute sarin surrogate sub-lethal dose exposure. Toxicology 2021; 456:152787. [PMID: 33887375 DOI: 10.1016/j.tox.2021.152787] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 04/11/2021] [Accepted: 04/15/2021] [Indexed: 11/15/2022]
Abstract
Warfare neurotoxicants such as sarin, soman or VX, are organophosphorus compounds which irreversibly inhibit cholinesterase. High-dose exposure with nerve agents (NA) is known to produce seizure activity and related brain damage, while less is known about the effects of acute sub-lethal dose exposure. The aim of this study was to characterize behavioral, brain activity and neuroinflammatory modifications at different time points after exposure to 4-nitrophenyl isopropyl methylphosphonate (NIMP), a sarin surrogate. In order to decipher the impacts of sub-lethal exposure, we chose 4 different doses of NIMP each corresponding to a fraction of the median lethal dose (LD50). First, we conducted a behavioral analysis of symptoms during the first hour following NIMP challenge and established a specific scoring scale for the intoxication severity. The intensity of intoxication signs was dose-dependent and proportional to the cholinesterase activity inhibition evaluated in mice brain. The lowest dose (0.3 LD50) did not induce significant behavioral, electrocorticographic (ECoG) nor cholinesterase activity changes. Animals exposed to one of the other doses (0.5, 0.7 and 0.9 LD50) exhibited substantial changes in behavior, significant cholinesterase activity inhibition, and a disruption of brainwave distribution that persisted in a dose-dependent manner. To evaluate long lasting changes, we conducted ECoG recording for 30 days on mice exposed to 0.5 or 0.9 LD50 of NIMP. Mice in both groups showed long-lasting impairment of theta rhythms, and a lack of restoration in hippocampal ChE activity after 1-month post-exposure. In addition, an increase in neuroinflammatory markers (IBA-1, TNF-α, NF-κB) and edema were transiently observed in mice hippocampus. Furthermore, a novel object recognition test showed an alteration of short-term memory in both groups, 1-month post-NIMP intoxication. Our findings identified both transient and long-term ECoG alterations and some long term cognitive impairments following exposure to sub-lethal doses of NIMP. These may further impact morphopathological alterations in the brain.
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Affiliation(s)
- Loïc Angrand
- Departement of Toxicology and Chemical Risks, French Armed Forces Biomedical Research Institute, Bretigny sur Orge, France; EnvA, IMRB, Maisons-Alfort, France; Université Paris-Est Créteil, INSERM, Team Relaix, Créteil, France
| | - Samir Takillah
- Departement of Neuroscience, Unit of Fatigue and Vigilance, French Armed Forces Biomedical Research Institute, Bretigny sur Orge, France; VIFASOM Team (EA 7330), Paris Descartes University, Sorbonne Paris Cité, Hôtel Dieu, Paris, France
| | - Isabelle Malissin
- Department of Medical and Toxicological Critical Care, Lariboisière Hospital, Federation of Toxicology APHP, Paris-Diderot University, INSERM UMRS-1144, Paris, France
| | - Asma Berriche
- Departement of Toxicology and Chemical Risks, French Armed Forces Biomedical Research Institute, Bretigny sur Orge, France; CEA, Fontenay aux roses, France
| | - Chloe Cervera
- Departement of Toxicology and Chemical Risks, French Armed Forces Biomedical Research Institute, Bretigny sur Orge, France
| | - Rosalie Bel
- Departement of Toxicology and Chemical Risks, French Armed Forces Biomedical Research Institute, Bretigny sur Orge, France
| | - Quentin Gerard
- Departement of Toxicology and Chemical Risks, French Armed Forces Biomedical Research Institute, Bretigny sur Orge, France; Normandie University, UNICAEN, INSERM, GIP Cyceron, Institut Blood and Brain @Caen-Normandie (BB@C), UMR-S U1237, Physiopathology and Imaging of Neurological Disorders (PhIND), Caen, France
| | - Julie Knoertzer
- Departement of Toxicology and Chemical Risks, French Armed Forces Biomedical Research Institute, Bretigny sur Orge, France
| | - Rachid Baati
- ICPEES UMR CNRS 7515, Institut de Chimie des Procédés, pour l'Energie, l'Environnement, et la Santé, Strasbourg, France
| | - Joseph P Kononchik
- Departement of Toxicology and Chemical Risks, French Armed Forces Biomedical Research Institute, Bretigny sur Orge, France
| | - Bruno Megarbane
- VIFASOM Team (EA 7330), Paris Descartes University, Sorbonne Paris Cité, Hôtel Dieu, Paris, France; Department of Medical and Toxicological Critical Care, Lariboisière Hospital, Federation of Toxicology APHP, Paris-Diderot University, INSERM UMRS-1144, Paris, France
| | - Karine Thibault
- Departement of Toxicology and Chemical Risks, French Armed Forces Biomedical Research Institute, Bretigny sur Orge, France.
| | - Gregory Dal Bo
- Departement of Toxicology and Chemical Risks, French Armed Forces Biomedical Research Institute, Bretigny sur Orge, France.
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16
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Dose- and time-related effects of acute diisopropylfluorophosphate intoxication on forced swim behavior and sucrose preference in rats. Neurotoxicology 2020; 82:82-88. [PMID: 33232745 DOI: 10.1016/j.neuro.2020.11.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/10/2020] [Accepted: 11/19/2020] [Indexed: 11/20/2022]
Abstract
Acute intoxication by organophosphorus anticholinesterases (OPs) has been associated with depression and other neuropsychiatric disorders. We previously reported that adult male rats treated with diisopropylfluorophosphate (2.5 mg/kg, sc) showed acute cholinergic signs followed by changes (increased immobility/decreased swimming) in the forced swim test (a measure of behavioral despair) for at least one month. This study was conducted to evaluate the further persistence of changes in the forced swim test out to 4 months and to compare responses in a sucrose preference test, a measure of anhedonia. Adult male rats were treated with vehicle (peanut oil, 1 mL/kg, sc) or DFP (2.0, 2.25 or 2.5 mg/kg) followed by sacrifice 4 h later for measurement of OP-sensitive serine hydrolases (cholinesterase [ChE], fatty acid amide hydrolase [FAAH], and monoacylglycerol lipase [MAGL]) in hippocampus. Additional rats were treated similarly and evaluated for functional signs of acute toxicity from 30 min to 6 days, and then motor activity, forced swim behavior and sucrose preference at approximately 1 week, 1 month and 4 months after dosing. All dosages of DFP elicited serine hydrolase inhibition (ChE, 92-96 %; FAAH, 46-63 %; MAGL, 26-33 %). Body weight was reduced in all DFP-treated groups during the first two weeks, and lethality was noted with the higher dosages. Involuntary movements were elicited in all DFP treatment groups during the first week, but both time of onset and rate of recovery were dose-related. There was a significant reduction in ambulation at one week after the highest dosage (2.5 mg/kg), but no other significant locomotor changes were noted. Immobility was increased and swimming was decreased in the forced swim test at all three time-points by 2.25 mg/kg DFP, and at 2 of 3 time-points by the other dosages. While length of water deprivation and time after DFP dosing affected sucrose preference, DFP treatment had no main effect. We conclude that the forced swim test (a measure of behavioral despair/coping mechanism for inescapable stress) is a robust and persistent neurobehavioral consequence of acute DFP intoxication while sucrose preference, a measure of anhedonia and a common symptom of major clinical depression, is not affected.
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17
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Reddy SD, Wu X, Kuruba R, Sridhar V, Reddy DS. Magnetic resonance imaging analysis of long-term neuropathology after exposure to the nerve agent soman: correlation with histopathology and neurological dysfunction. Ann N Y Acad Sci 2020; 1480:116-135. [PMID: 32671850 PMCID: PMC7708405 DOI: 10.1111/nyas.14431] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 05/09/2020] [Accepted: 06/17/2020] [Indexed: 12/14/2022]
Abstract
Nerve agents (NAs) produce acute and long-term brain injury and dysfunction, as evident from the Japan and Syria incidents. Magnetic resonance imaging (MRI) is a versatile technique to examine such chronic anatomical, functional, and neuronal damage in the brain. The objective of this study was to investigate long-term structural and neuronal lesion abnormalities in rats exposed to acute soman intoxication. T2-weighted MRI images of 10 control and 17 soman-exposed rats were acquired using a Siemens MRI system at 90 days after soman exposure. Quantification of brain tissue volumes and T2 signal intensity was conducted using the Inveon Research Workplace software and the extent of damage was correlated with histopathology and cognitive function. Soman-exposed rats showed drastic hippocampal atrophy with neuronal loss and reduced hippocampal volume (HV), indicating severe damage, but had similar T2 relaxation times to the control group, suggesting limited scarring and fluid density changes despite the volume decrease. Conversely, soman-exposed rats displayed significant increases in lateral ventricle volumes and T2 times, signifying strong cerebrospinal fluid expansion in compensation for tissue atrophy. The total brain volume, thalamic volume, and thalamic T2 time were similar in both groups, however, suggesting that some brain regions remained more intact long-term after soman intoxication. The MRI neuronal lesions were positively correlated with the histological markers of neurodegeneration and neuroinflammation 90 days after soman exposure. The predominant MRI hippocampal atrophy (25%) was highly consistent with massive reduction (35%) of neuronal nuclear antigen-positive (NeuN+ ) principal neurons and parvalbumin-positive (PV+ ) inhibitory interneurons within this brain region. The HV was significantly correlated with both inflammatory markers of GFAP+ astrogliosis and IBA1+ microgliosis. The reduced HV was also directly correlated with significant memory deficits in the soman-exposed cohort, confirming a possible neurobiological basis for neurological dysfunction. Together, these findings provide powerful insight on long-term region-specific neurodegenerative patterns after soman exposure and demonstrate the feasibility of in vivo neuroimaging to monitor neuropathology, predict the risk of neurological deficits, and evaluate response to medical countermeasures for NAs.
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Affiliation(s)
- Sandesh D Reddy
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, Bryan, Texas
- Biomedical Engineering, College of Engineering, Texas A&M University, College Station, Texas
| | - Xin Wu
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, Bryan, Texas
| | - Ramkumar Kuruba
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, Bryan, Texas
| | - Vidya Sridhar
- Texas A&M Institute for Preclinical Studies, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas
| | - Doodipala Samba Reddy
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, Bryan, Texas
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Dhir A, Bruun DA, Guignet M, Tsai Y, González E, Calsbeek J, Vu J, Saito N, Tancredi DJ, Harvey DJ, Lein PJ, Rogawski MA. Allopregnanolone and perampanel as adjuncts to midazolam for treating diisopropylfluorophosphate-induced status epilepticus in rats. Ann N Y Acad Sci 2020; 1480:183-206. [PMID: 32915470 PMCID: PMC7756871 DOI: 10.1111/nyas.14479] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 07/29/2020] [Accepted: 08/06/2020] [Indexed: 12/11/2022]
Abstract
Combinations of midazolam, allopregnanolone, and perampanel were assessed for antiseizure activity in a rat diisopropylfluorophosphate (DFP) status epilepticus model. Animals receiving DFP followed by atropine and pralidoxime exhibited continuous high-amplitude rhythmical electroencephalography (EEG) spike activity and behavioral seizures for more than 5 hours. Treatments were administered intramuscularly 40 min after DFP. Seizures persisted following midazolam (1.8 mg/kg). The combination of midazolam with either allopregnanolone (6 mg/kg) or perampanel (2 mg/kg) terminated EEG and behavioral status epilepticus, but the onset of the perampanel effect was slow. The combination of midazolam, allopregnanolone, and perampanel caused rapid and complete suppression of EEG and behavioral seizures. In the absence of DFP, animals treated with the three-drug combination were sedated but not anesthetized. Animals that received midazolam alone exhibited spontaneous recurrent EEG seizures, whereas those that received the three-drug combination did not, demonstrating antiepileptogenic activity. All combination treatments reduced neurodegeneration as assessed with Fluoro-Jade C staining to a greater extent than midazolam alone, and most reduced astrogliosis as assessed by GFAP immunoreactivity but had mixed effects on markers of microglial activation. We conclude that allopregnanolone, a positive modulator of the GABAA receptor, and perampanel, an AMPA receptor antagonist, are potential adjuncts to midazolam in the treatment of benzodiazepine-refractory organophosphate nerve agent-induced status epilepticus.
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Affiliation(s)
- Ashish Dhir
- Department of Neurology, School of MedicineUniversity of California, DavisSacramentoCalifornia
| | - Donald A. Bruun
- Department of Molecular Biosciences, School of Veterinary MedicineUniversity of California, DavisDavisCalifornia
| | - Michelle Guignet
- Department of Molecular Biosciences, School of Veterinary MedicineUniversity of California, DavisDavisCalifornia
| | - Yi‐Hua Tsai
- Department of Molecular Biosciences, School of Veterinary MedicineUniversity of California, DavisDavisCalifornia
| | - Eduardo González
- Department of Molecular Biosciences, School of Veterinary MedicineUniversity of California, DavisDavisCalifornia
| | - Jonas Calsbeek
- Department of Molecular Biosciences, School of Veterinary MedicineUniversity of California, DavisDavisCalifornia
| | - Joan Vu
- Department of Molecular Biosciences, School of Veterinary MedicineUniversity of California, DavisDavisCalifornia
| | - Naomi Saito
- Department of Public Health Sciences, School of MedicineUniversity of California, DavisDavisCalifornia
| | - Daniel J. Tancredi
- Department of Pediatrics, School of MedicineUniversity of California, DavisSacramentoCalifornia
| | - Danielle J. Harvey
- Department of Public Health Sciences, School of MedicineUniversity of California, DavisDavisCalifornia
| | - Pamela J. Lein
- Department of Molecular Biosciences, School of Veterinary MedicineUniversity of California, DavisDavisCalifornia
| | - Michael A. Rogawski
- Department of Neurology, School of MedicineUniversity of California, DavisSacramentoCalifornia
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19
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Acute administration of diazepam or midazolam minimally alters long-term neuropathological effects in the rat brain following acute intoxication with diisopropylfluorophosphate. Eur J Pharmacol 2020; 886:173538. [PMID: 32898549 DOI: 10.1016/j.ejphar.2020.173538] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 09/01/2020] [Accepted: 09/03/2020] [Indexed: 12/30/2022]
Abstract
Acute intoxication with organophosphorus cholinesterase inhibitors (OPs) can trigger seizures that rapidly progress to life-threatening status epilepticus. Diazepam, long considered the standard of care for treating OP-induced seizures, is being replaced by midazolam. Whether midazolam is more effective than diazepam in mitigating the persistent effects of acute OP intoxication has not been rigorously evaluated. We compared the efficacy of diazepam vs. midazolam in preventing persistent neuropathology in adult male Sprague-Dawley rats acutely intoxicated with the OP diisopropylfluorophosphate (DFP). Subjects were administered pyridostigmine bromide (0.1 mg/kg, i.p.) 30 min prior to injection with DFP (4 mg/kg, s.c.) or vehicle (saline) followed 1 min later by atropine sulfate (2 mg/kg, i.m.) and pralidoxime (25 mg/kg, i.m.), and 40 min later by diazepam (5 mg/kg, i.p.), midazolam (0.73 mg/kg, i.m.), or vehicle. At 3 and 6 months post-exposure, neurodegeneration, reactive astrogliosis, microglial activation, and oxidative stress were assessed in multiple brain regions using quantitative immunohistochemistry. Brain mineralization was evaluated by in vivo micro-computed tomography (micro-CT). Acute DFP intoxication caused persistent neurodegeneration, neuroinflammation, and brain mineralization. Midazolam transiently mitigated neurodegeneration, and both benzodiazepines partially protected against reactive astrogliosis in a brain region-specific manner. Neither benzodiazepine attenuated microglial activation or brain mineralization. These findings indicate that neither benzodiazepine effectively protects against persistent neuropathological changes, and suggest that midazolam is not significantly better than diazepam. Overall, this study highlights the need for improved neuroprotective strategies for treating humans in the event of a chemical emergency involving OPs.
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