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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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Pirollo KF, Moghe M, Guan M, Rait AS, Wang A, Kim SS, Chang EH, Harford JB. A Pralidoxime Nanocomplex Formulation Targeting Transferrin Receptors for Reactivation of Brain Acetylcholinesterase After Exposure of Mice to an Anticholinesterase Organophosphate. Int J Nanomedicine 2024; 19:307-326. [PMID: 38229703 PMCID: PMC10790653 DOI: 10.2147/ijn.s443498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Accepted: 12/25/2023] [Indexed: 01/18/2024] Open
Abstract
Introduction Organophosphates are among the deadliest of known chemicals based on their ability to inactivate acetylcholinesterase in neuromuscular junctions and synapses of the central and peripheral nervous systems. The consequent accumulation of acetylcholine can produce severe acute toxicities and death. Oxime antidotes act by reactivating acetylcholinesterase with the only such reactivator approved for use in the United States being 2-pyridine aldoxime methyl chloride (a.k.a., pralidoxime or 2-PAM). However, this compound does not cross the blood-brain barrier readily and so is limited in its ability to reactivate acetylcholinesterase in the brain. Methods We have developed a novel formulation of 2-PAM by encapsulating it within a nanocomplex designed to cross the blood-brain barrier via transferrin receptor-mediated transcytosis. This nanocomplex (termed scL-2PAM) has been subjected to head-to-head comparisons with unencapsulated 2-PAM in mice exposed to paraoxon, an organophosphate with anticholinesterase activity. Results and Discussion In mice exposed to a sublethal dose of paraoxon, scL-2PAM reduced the extent and duration of cholinergic symptoms more effectively than did unencapsulated 2-PAM. The scL-2PAM formulation was also more effective than unencapsulated 2-PAM in rescuing mice from death after exposure to otherwise-lethal levels of paraoxon. Improved survival rates in paraoxon-exposed mice were accompanied by a higher degree of reactivation of brain acetylcholinesterase. Conclusion Our data indicate that scL-2PAM is superior to the currently used form of 2-PAM in terms of both mitigating paraoxon toxicity in mice and reactivating acetylcholinesterase in their brains.
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Affiliation(s)
- Kathleen F Pirollo
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, 20057, USA
| | - Manish Moghe
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, 20057, USA
| | - Miaoyin Guan
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, 20057, USA
| | - Antonina S Rait
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, 20057, USA
| | - Aibing Wang
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, 20057, USA
| | - Sang-Soo Kim
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, 20057, USA
- SynerGene Therapeutics, Inc., Potomac, MD, 20854, USA
| | - Esther H Chang
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, 20057, USA
| | - Joe B Harford
- SynerGene Therapeutics, Inc., Potomac, MD, 20854, USA
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Gage M, Vinithakumari AA, Mooyottu S, Thippeswamy T. Gut dysbiosis following organophosphate, diisopropylfluorophosphate (DFP), intoxication and saracatinib oral administration. FRONTIERS IN MICROBIOMES 2022; 1:1006078. [PMID: 37304619 PMCID: PMC10256240 DOI: 10.3389/frmbi.2022.1006078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Organophosphate nerve agents (OPNAs) act as irreversible inhibitors of acetylcholinesterase and can lead to cholinergic crisis including salivation, lacrimation, urination, defecation, gastrointestinal distress, respiratory distress, and seizures. Although the OPNAs have been studied in the past few decades, little is known about the impact on the gut microbiome which has become of increasing interest across fields. In this study, we challenged animals with the OPNA, diisopropylfluorophosphate (DFP, 4mg/kg, s.c.) followed immediately by 2mg/kg atropine sulfate (i.m.) and 25mg/kg 2-pralidoxime (i.m.) and 30 minutes later by 3mg/kg midazolam (i.m.). One hour after midazolam, animals were treated with a dosing regimen of saracatinib (SAR, 20mg/kg, oral), a src family kinase inhibitor, to mitigate DFP-induced neurotoxicity. We collected fecal samples 48 hours, 7 days, and 5 weeks post DFP intoxication. 16S rRNA genes (V4) were amplified to identify the bacterial composition. At 48 hours, a significant increase in the abundance of Proteobacteria and decrease in the abundance of Firmicutes were observed in DFP treated animals. At 7 days there was a significant reduction in Firmicutes and Actinobacteria, but a significant increase in Bacteroidetes in the DFP groups compared to controls. The taxonomic changes at 5 weeks were negligible. There was no impact of SAR administration on microbial composition. There was a significant DFP-induced reduction in alpha diversity at 48 hours but not at 7 days and 5 weeks. There appeared to be an impact of DFP on beta diversity at 48 hours and 7 days but not at 5 weeks. In conclusion, acute doses of DFP lead to short-term gut dysbiosis and SAR had no effect. Understanding the role of gut dysbiosis in long-term toxicity may reveal therapeutic targets.
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Affiliation(s)
- Meghan Gage
- Interdepartmental Neuroscience, The Departments of Biomedical Sciences, Iowa State University, Ames, IA, United States
| | - Akhil A. Vinithakumari
- Veterinary Pathology, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Shankumar Mooyottu
- Veterinary Pathology, College of Veterinary Medicine, Iowa State University, Ames, IA, United States
| | - Thimmasettappa Thippeswamy
- Interdepartmental Neuroscience, The Departments of Biomedical Sciences, Iowa State University, Ames, IA, United States
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Somkhit J, Yanicostas C, Soussi-Yanicostas N. Microglia Remodelling and Neuroinflammation Parallel Neuronal Hyperactivation Following Acute Organophosphate Poisoning. Int J Mol Sci 2022; 23:ijms23158240. [PMID: 35897817 PMCID: PMC9332153 DOI: 10.3390/ijms23158240] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Revised: 07/08/2022] [Accepted: 07/13/2022] [Indexed: 01/27/2023] Open
Abstract
Organophosphate (OP) compounds include highly toxic chemicals widely used both as pesticides and as warfare nerve agents. Existing countermeasures are lifesaving, but do not alleviate all long-term neurological sequelae, making OP poisoning a public health concern worldwide and the search for fully efficient antidotes an urgent need. OPs cause irreversible acetylcholinesterase (AChE) inhibition, inducing the so-called cholinergic syndrome characterized by peripheral manifestations and seizures associated with permanent psychomotor deficits. Besides immediate neurotoxicity, recent data have also identified neuroinflammation and microglia activation as two processes that likely play an important, albeit poorly understood, role in the physiopathology of OP intoxication and its long-term consequences. To gain insight into the response of microglia to OP poisoning, we used a previously described model of diisopropylfluorophosphate (DFP) intoxication of zebrafish larvae. This model reproduces almost all the defects seen in poisoned humans and preclinical models, including AChE inhibition, neuronal epileptiform hyperexcitation, and increased neuronal death. Here, we investigated in vivo the consequences of acute DFP exposure on microglia morphology and behaviour, and on the expression of a set of pro- and anti-inflammatory cytokines. We also used a genetic method of microglial ablation to evaluate the role in the OP-induced neuropathology. We first showed that DFP intoxication rapidly induced deep microglial phenotypic remodelling resembling that seen in M1-type activated macrophages and characterized by an amoeboid morphology, reduced branching, and increased mobility. DFP intoxication also caused massive expression of genes encoding pro-inflammatory cytokines Il1β, Tnfα, Il8, and to a lesser extent, immuno-modulatory cytokine Il4, suggesting complex microglial reprogramming that included neuroinflammatory activities. Finally, microglia-depleted larvae were instrumental in showing that microglia were major actors in DFP-induced neuroinflammation and, more importantly, that OP-induced neuronal hyperactivation was markedly reduced in larvae fully devoid of microglia. DFP poisoning rapidly triggered massive microglia-mediated neuroinflammation, probably as a result of DFP-induced neuronal hyperexcitation, which in turn further exacerbated neuronal activation. Microglia are thus a relevant therapeutic target, and identifying substances reducing microglial activation could add efficacy to existing OP antidote cocktails.
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Gage M, Putra M, Wachter L, Dishman K, Gard M, Gomez-Estrada C, Thippeswamy T. Saracatinib, a Src Tyrosine Kinase Inhibitor, as a Disease Modifier in the Rat DFP Model: Sex Differences, Neurobehavior, Gliosis, Neurodegeneration, and Nitro-Oxidative Stress. Antioxidants (Basel) 2021; 11:61. [PMID: 35052568 PMCID: PMC8773289 DOI: 10.3390/antiox11010061] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Revised: 12/17/2021] [Accepted: 12/23/2021] [Indexed: 12/13/2022] Open
Abstract
Diisopropylfluorophosphate (DFP), an organophosphate nerve agent (OPNA), exposure causes status epilepticus (SE) and epileptogenesis. In this study, we tested the protective effects of saracatinib (AZD0530), a Src kinase inhibitor, in mixed-sex or male-only Sprague Dawley rats exposed to 4-5 mg/kg DFP followed by 2 mg/kg atropine and 25 mg/kg 2-pralidoxime. Midazolam (3 mg/kg) was given to the mixed-sex cohort (1 h post-DFP) and male-only cohort (~30 min post-DFP). Saracatinib (20 mg/kg, oral, daily for 7 days) or vehicle was given two hours later and euthanized eight days or ten weeks post-DFP. Brain immunohistochemistry (IHC) showed increased microgliosis, astrogliosis, and neurodegeneration in DFP-treated animals. In the 10-week post-DFP male-only group, there were no significant differences between groups in the novel object recognition, Morris water maze, rotarod, or forced swim test. Brain IHC revealed significant mitigation by saracatinib in contrast to vehicle-treated DFP animals in microgliosis, astrogliosis, neurodegeneration, and nitro-oxidative stressors, such as inducible nitric oxide synthase, GP91phox, and 3-Nitrotyrosine. These findings suggest the protective effects of saracatinib on brain pathology seem to depend on the initial SE severity. Further studies on dose optimization, including extended treatment regimen depending on the SE severity, are required to determine its disease-modifying potential in OPNA models.
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Affiliation(s)
| | | | | | | | | | | | - Thimmasettappa Thippeswamy
- Department of Biomedical Sciences and Interdepartmental Neuroscience Program, Iowa State University, Ames, IA 50011, USA; (M.G.); (M.P.); (L.W.); (K.D.); (M.G.); (C.G.-E.)
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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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Chen J, Zhang Y, Chai Y, Meng Z, Zhang Y, Chen L, Quan D, Wang Y, Meng Q, Li C. Synergistic enhancement of the emergency treatment effect of organophosphate poisoning by a supramolecular strategy. Chem Sci 2021; 12:5202-5208. [PMID: 34163757 PMCID: PMC8179580 DOI: 10.1039/d1sc00426c] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 02/24/2021] [Indexed: 01/19/2023] Open
Abstract
Poisoning by organophosphorus agents (OPs) is a serious public health issue across the world. These compounds irreversibly inhibit acetylcholinesterase (AChE), resulting in the accumulation of acetylcholine (ACh) and overstimulation of ACh receptors. A supramolecular detoxification system (SDS) has been designed with a view to deliver pyridine-2-aldoxime methochloride (PAM) with a synergistic inhibition effect on the ACh-induced hyperstimulation through host-guest encapsulation. NMR and fluorescence titration served to confirm the complexation between carboxylatopillar[6]arene (CP6A) and PAM as well as ACh with robust affinities. Patch-clamp studies proved that CP6A could exert an inhibition effect on the ACh-induced hyperstimulation of ACh receptors. Support for the feasibility of this strategy came from fluorescence imaging results. In vivo studies revealed that complexation by CP6A serves to increase the AChE reactivation efficiency of PAM. The formation of the PAM/CP6A complex contributed to enhance in a statistically significant way the ability of PAM not only to relieve symptoms of seizures but also to improve the survival ratio in paraoxon-poisoned model rats. These favorable findings are attributed to synergistic effects that PAM reactivates AChE to hydrolyze ACh and excess ACh is encapsulated in the cavity of CP6A to relieve cholinergic crisis symptoms.
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Affiliation(s)
- Junyi Chen
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology Beijing 100850 P. R. China
- College of Environmental and Chemical Engineering, Shanghai University Shanghai 200444 P. R. China
| | - Yadan Zhang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology Beijing 100850 P. R. China
| | - Yao Chai
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology Beijing 100850 P. R. China
| | - Zhao Meng
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology Beijing 100850 P. R. China
| | - Yahan Zhang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology Beijing 100850 P. R. China
| | - Longming Chen
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology Beijing 100850 P. R. China
| | - Dongqin Quan
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology Beijing 100850 P. R. China
| | - Yongan Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology Beijing 100850 P. R. China
| | - Qingbin Meng
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology Beijing 100850 P. R. China
| | - Chunju Li
- College of Environmental and Chemical Engineering, Shanghai University Shanghai 200444 P. R. China
- Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry, Ministry of Education, Tianjin Key Laboratory of Structure and Performance for Functional Molecules, College of Chemistry, Tianjin Normal University Tianjin 300387 P. R. China
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Rojas A, McCarren HS, Wang J, Wang W, Abreu-Melon J, Wang S, McDonough JH, Dingledine R. Comparison of neuropathology in rats following status epilepticus induced by diisopropylfluorophosphate and soman. Neurotoxicology 2021; 83:14-27. [PMID: 33352274 PMCID: PMC7987879 DOI: 10.1016/j.neuro.2020.12.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 12/07/2020] [Accepted: 12/16/2020] [Indexed: 12/29/2022]
Abstract
The increasing number of cases involving the use of nerve agents as deadly weapons has spurred investigation into the molecular mechanisms underlying nerve agent-induced pathology. The highly toxic nature of nerve agents restrict their use in academic research laboratories. Less toxic organophosphorus (OP) based agents including diisopropylfluorophosphate (DFP) are used as surrogates in academic research laboratories to mimic nerve agent poisoning. However, neuropathology resulting from DFP-induced status epilepticus (SE) has not been compared directly to neuropathology observed following nerve agent poisoning in the same study. Here, the hypothesis that neuropathology measured four days after SE is the same for rats exposed to DFP and soman was tested. Adult Sprague-Dawley rats were injected with soman or DFP to induce SE. Cortical electroencephalography (EEG) was recorded prior to and during soman-induced SE. EEG power analysis of rats administered soman revealed prolonged electrographic SE similar to that of rats that endure uninterrupted SE following injection of DFP. Rats that experienced soman-induced SE displayed less hippocampal neuroinflammation and gliosis compared to rats administered DFP. Seizure-induced weight change, blood-brain barrier (BBB) leakiness and neurodegeneration in most seizure sensitive limbic brain regions were similar for rats that endured SE following soman or DFP. The amalgamated pathology score calculated by combining pathological measures (weight loss, hippocampal neuroinflammation, gliosis, BBB integrity and neurodegeneration) was similar in rats administered the OP agents. These findings support use of the rat DFP model of SE as a suitable surrogate for investigating some, but not all delayed consequences produced by nerve agents.
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Affiliation(s)
- Asheebo Rojas
- Department of Pharmacology and Chemical Biology, Emory University, 1510 Clifton Road NE, Atlanta, GA, 30322, United States.
| | - Hilary S McCarren
- Neuroscience Department, Medical Toxicology Research Division, United States Army Medical Research Institute of Chemical Defense, 8350 Ricketts Point Rd, Aberdeen Proving Ground, MD, 21010, United States
| | - Jennifer Wang
- Department of Pharmacology and Chemical Biology, Emory University, 1510 Clifton Road NE, Atlanta, GA, 30322, United States
| | - Wenyi Wang
- Department of Pharmacology and Chemical Biology, Emory University, 1510 Clifton Road NE, Atlanta, GA, 30322, United States
| | - JuanMartin Abreu-Melon
- Department of Pharmacology and Chemical Biology, Emory University, 1510 Clifton Road NE, Atlanta, GA, 30322, United States
| | - Sarah Wang
- Department of Pharmacology and Chemical Biology, Emory University, 1510 Clifton Road NE, Atlanta, GA, 30322, United States
| | - John H McDonough
- Neuroscience Department, Medical Toxicology Research Division, United States Army Medical Research Institute of Chemical Defense, 8350 Ricketts Point Rd, Aberdeen Proving Ground, MD, 21010, United States
| | - Raymond Dingledine
- Department of Pharmacology and Chemical Biology, Emory University, 1510 Clifton Road NE, Atlanta, GA, 30322, United States
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Brenet A, Somkhit J, Hassan-Abdi R, Yanicostas C, Romain C, Bar O, Igert A, Saurat D, Taudon N, Dal-Bo G, Nachon F, Dupuis N, Soussi-Yanicostas N. Organophosphorus diisopropylfluorophosphate (DFP) intoxication in zebrafish larvae causes behavioral defects, neuronal hyperexcitation and neuronal death. Sci Rep 2020; 10:19228. [PMID: 33154418 PMCID: PMC7645799 DOI: 10.1038/s41598-020-76056-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 10/19/2020] [Indexed: 11/09/2022] Open
Abstract
With millions of intoxications each year and over 200,000 deaths, organophosphorus (OP) compounds are an important public health issue worldwide. OP poisoning induces cholinergic syndrome, with respiratory distress, hypertension, and neuron damage that may lead to epileptic seizures and permanent cognitive deficits. Existing countermeasures are lifesaving but do not prevent long-lasting neuronal comorbidities, emphasizing the urgent need for animal models to better understand OP neurotoxicity and identify novel antidotes. Here, using diisopropylfluorophosphate (DFP), a prototypic and moderately toxic OP, combined with zebrafish larvae, we first showed that DFP poisoning caused major acetylcholinesterase inhibition, resulting in paralysis and CNS neuron hyperactivation, as indicated by increased neuronal calcium transients and overexpression of the immediate early genes fosab, junBa, npas4b, and atf3. In addition to these epileptiform seizure-like events, DFP-exposed larvae showed increased neuronal apoptosis, which were both partially alleviated by diazepam treatment, suggesting a causal link between neuronal hyperexcitation and cell death. Last, DFP poisoning induced an altered balance of glutamatergic/GABAergic synaptic activity with increased NR2B-NMDA receptor accumulation combined with decreased GAD65/67 and gephyrin protein accumulation. The zebrafish DFP model presented here thus provides important novel insights into the pathophysiology of OP intoxication, making it a promising model to identify novel antidotes.
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Affiliation(s)
| | - Julie Somkhit
- NeuroDiderot, Inserm, Université de Paris, 75019, Paris, France
| | | | | | | | - Olivier Bar
- NeuroDiderot, Inserm, Université de Paris, 75019, Paris, France
| | - Alexandre Igert
- Département de toxicologie et risques chimiques, Institut de Recherche Biomédicale des Armées (IRBA), 91 220, Brétigny-sur-Orge, France
| | - Dominique Saurat
- Institut de Recherche Biomédicale des Armées (IRBA), Unité de Développements Analytiques et Bioanalyse, 91 220, Brétigny-sur-Orge, France
| | - Nicolas Taudon
- Institut de Recherche Biomédicale des Armées (IRBA), Unité de Développements Analytiques et Bioanalyse, 91 220, Brétigny-sur-Orge, France
| | - Gregory Dal-Bo
- Département de toxicologie et risques chimiques, Institut de Recherche Biomédicale des Armées (IRBA), 91 220, Brétigny-sur-Orge, France
| | - Florian Nachon
- Département de toxicologie et risques chimiques, Institut de Recherche Biomédicale des Armées (IRBA), 91 220, Brétigny-sur-Orge, France
| | - Nina Dupuis
- Département de toxicologie et risques chimiques, Institut de Recherche Biomédicale des Armées (IRBA), 91 220, Brétigny-sur-Orge, France
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10
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Putra M, Gage M, Sharma S, Gardner C, Gasser G, Anantharam V, Thippeswamy T. Diapocynin, an NADPH oxidase inhibitor, counteracts diisopropylfluorophosphate-induced long-term neurotoxicity in the rat model. Ann N Y Acad Sci 2020; 1479:75-93. [PMID: 32037612 PMCID: PMC7415478 DOI: 10.1111/nyas.14314] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 01/14/2020] [Accepted: 01/25/2020] [Indexed: 12/18/2022]
Abstract
Organophosphate (OP) nerve agents are a threat to both the military and civilians. OP exposure causes cholinergic crisis and status epilepticus (SE) because of irreversible inhibition of acetylcholinesterase that can be life-threatening if left untreated. OP survivors develop long-term morbidity, such as cognitive impairment and motor dysfunction, because of oxidative stress and progressive neuroinflammation and neurodegeneration, which act as disease promoters. Current medical countermeasures (MCMs) do not mitigate these pathologies. Therefore, our goal was to target these disease promoters using diapocynin (DPO), an NADPH oxidase inhibitor, in addition to MCMs, in a rat diisopropylfluorophosphate (DFP) model. The DFP-intoxicated rats were treated with DPO (300 mg/kg, oral, six doses, 12-h intervals) or vehicle 2 h following behavioral SE termination with diazepam. The DPO treatment significantly rescued DFP-induced motor impairment and attenuated epileptiform spiking during the first 72 h after DFP exposure in severely seizing rats despite no difference in epileptiform spike rate between the vehicle and DPO groups in mild SE rats. DPO significantly reduced DFP-induced reactive astrogliosis, neurodegeneration, GP91phox , glutathiolated protein, serum nitrite, and proinflammatory cytokines and chemokines, such as interleukins (ILs) IL-1α, IL-6, IL-2, IL-17A, leptin, and IP-10, in the hippocampus. Collectively, these data support a neuroprotective role of DPO in an OP-induced neurotoxicity model.
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Affiliation(s)
- Marson Putra
- Neuroscience Graduate Program, Iowa State University, Ames, IA 50011
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011
| | - Meghan Gage
- Neuroscience Graduate Program, Iowa State University, Ames, IA 50011
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011
| | - Shaunik Sharma
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011
| | - Cara Gardner
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011
| | | | | | - Thimmasettappa Thippeswamy
- Neuroscience Graduate Program, Iowa State University, Ames, IA 50011
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011
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11
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Rojas A, Ganesh T, Wang W, Wang J, Dingledine R. A rat model of organophosphate-induced status epilepticus and the beneficial effects of EP2 receptor inhibition. Neurobiol Dis 2020; 133:104399. [PMID: 30818067 PMCID: PMC6708729 DOI: 10.1016/j.nbd.2019.02.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 01/29/2019] [Accepted: 02/20/2019] [Indexed: 02/06/2023] Open
Abstract
This review describes an adult rat model of status epilepticus (SE) induced by diisopropyl fluorophosphate (DFP), and the beneficial outcomes of transient inhibition of the prostaglandin-E2 receptor EP2 with a small molecule antagonist, delayed by 2-4 h after SE onset. Administration of six doses of the selective EP2 antagonist TG6-10-1 over a 2-3 day period accelerates functional recovery, attenuates hippocampal neurodegeneration, neuroinflammation, gliosis and blood-brain barrier leakage, and prevents long-term cognitive deficits without blocking SE itself or altering acute seizure characteristics. This work has provided important information regarding organophosphate-induced seizure related pathologies in adults and revealed the effectiveness of delayed EP2 inhibition to combat these pathologies.
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Affiliation(s)
- Asheebo Rojas
- Department of Pharmacology, Emory University, 1510 Clifton Road NE, Atlanta, GA 30322, USA.
| | - Thota Ganesh
- Department of Pharmacology, Emory University, 1510 Clifton Road NE, Atlanta, GA 30322, USA
| | - Wenyi Wang
- Department of Pharmacology, Emory University, 1510 Clifton Road NE, Atlanta, GA 30322, USA
| | - Jennifer Wang
- Department of Pharmacology, Emory University, 1510 Clifton Road NE, Atlanta, GA 30322, USA
| | - Raymond Dingledine
- Department of Pharmacology, Emory University, 1510 Clifton Road NE, Atlanta, GA 30322, USA
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12
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Diauudin FN, Rashid JIA, Knight VF, Wan Yunus WMZ, Ong KK, Kasim NAM, Abdul Halim N, Noor SAM. A review of current advances in the detection of organophosphorus chemical warfare agents based biosensor approaches. SENSING AND BIO-SENSING RESEARCH 2019. [DOI: 10.1016/j.sbsr.2019.100305] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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13
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Neuroterrorism and Drug Overdose in the Neurocritical Care Unit. Neurocrit Care 2019. [DOI: 10.1017/9781107587908.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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14
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Epigenetic and autophagic changes after nerve agent exposure in the rat piriform cortex and hippocampus. Toxicology 2019; 423:54-61. [DOI: 10.1016/j.tox.2019.05.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 04/17/2019] [Accepted: 05/13/2019] [Indexed: 11/18/2022]
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15
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Liang LP, Pearson-Smith JN, Huang J, McElroy P, Day BJ, Patel M. Neuroprotective Effects of AEOL10150 in a Rat Organophosphate Model. Toxicol Sci 2019; 162:611-621. [PMID: 29272548 DOI: 10.1093/toxsci/kfx283] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Prolonged seizure activity or status epilepticus (SE) is one of the most critical manifestations of organophosphate exposure. Previous studies in our laboratory have demonstrated that oxidative stress is a critical mediator of SE-induced neuronal injury. The goal of this study was to determine if diisopropylflurorphoshate (DFP) exposure in rats resulted in oxidative stress and whether scavenging reactive oxygen species attenuated DFP-induced neurotoxicity. DFP treatment increased indices of oxidative stress in a time- and region- dependent manner. Neuronal loss measured by Fluoro-Jade B staining was significantly increased in the hippocampus, piriform cortex and amygdala following DFP. Similarly, levels of the proinflammatory cytokines, particularly TNF-α, IL-6, and KC/GRO were significantly increased in the piriform cortex and in the hippocampus following DFP treatment. The catalytic antioxidant AEOL10150, when treatment was initiated 5 min after DFP-induced SE, significantly attenuated indices of oxidative stress, neuroinflammation and neuronal damage. This study suggests that catalytic antioxidant treatment may be useful as a novel therapy to attenuate secondary neuronal injury following organophosphate exposure.
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Affiliation(s)
- Li-Ping Liang
- Department of Pharmaceutical Sciences, University of Colorado Denver, Aurora, Colorado
| | | | - Jie Huang
- Department of Medicine, National Jewish Health, Denver, Colorado
| | - Pallavi McElroy
- Department of Pharmaceutical Sciences, University of Colorado Denver, Aurora, Colorado
| | - Brian J Day
- Department of Pharmaceutical Sciences, University of Colorado Denver, Aurora, Colorado.,Department of Medicine, National Jewish Health, Denver, Colorado
| | - Manisha Patel
- Department of Pharmaceutical Sciences, University of Colorado Denver, Aurora, Colorado
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16
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Neuroprotective effects of a catalytic antioxidant in a rat nerve agent model. Redox Biol 2018; 20:275-284. [PMID: 30384261 PMCID: PMC6215030 DOI: 10.1016/j.redox.2018.10.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 10/10/2018] [Accepted: 10/13/2018] [Indexed: 12/19/2022] Open
Abstract
Persistent inhibition of acetylcholinesterase resulting from exposure to nerve agents such as soman, is associated with prolonged seizure activity known as status epilepticus (SE). Without medical countermeasures, exposure to soman and resultant SE leads to high morbidity and mortality. Currently available therapeutics are effective in limiting mortality, however effects on morbidity are highly time-dependent and rely on the ability to suppress SE. We have previously demonstrated significant protection from secondary neuronal injury in surrogate nerve agent models by targeting oxidative stress. However, whether oxidative stress represents a relevant therapeutic target in genuine nerve agent toxicity is unknown. Here, we demonstrate that soman exposure results in robust region- and time-dependent oxidative stress. Targeting this oxidative stress in a post-exposure paradigm using a small molecular weight, broad spectrum catalytic antioxidant, was sufficient to attenuate brain and plasma oxidative stress, neuroinflammation and neurodegeneration. Thus, targeting of oxidative stress in a post-exposure paradigm can mitigate secondary neuronal injury following soman exposure. Soman exposure results in time- and region- dependent oxidative stress in brain. A catalytic antioxidant inhibited oxidative stress, neuroinflammation and degeneration. Post-exposure treatment with the antioxidant attenuates secondary neuronal injury.
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17
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Requena M, Parrón T, Navarro A, García J, Ventura MI, Hernández AF, Alarcón R. Association between environmental exposure to pesticides and epilepsy. Neurotoxicology 2018; 68:13-18. [PMID: 30018027 DOI: 10.1016/j.neuro.2018.07.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 06/22/2018] [Accepted: 07/02/2018] [Indexed: 12/21/2022]
Abstract
There is increasing evidence of an association between long-term environmental exposure to pesticides and neurodegenerative disorders; however, the relationship with epilepsy has not been addressed thus far. This study was aimed at determining the prevalence and risk of developing epilepsy among people from South-East Spain living in areas of high vs. low exposure to pesticides based on agronomic data. The study population consisted of 4007 subjects with a diagnosis of epilepsy and 580,077 control subjects adjusted for age, sex and geographical area. Data were collected from hospital records of the Spanish health care system (basic minimum dataset) between the years 1998 and 2010. The prevalence of epilepsy was significantly higher in areas of greater pesticide use relative to areas of lesser use. Overall, an increased risk of epilepsy was observed in the population living in areas of high vs. low use of pesticides (OR: 1.65; p < 0.001). Although this study was exploratory in nature, the results suggest that environmental exposure to pesticides might increase the risk of having epilepsy.
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Affiliation(s)
- Mar Requena
- University of Almería School of Health Sciences, Almería, Spain.
| | - Tesifón Parrón
- University of Almería School of Health Sciences, Almería, Spain; Andalusian Council of Health at Almería Province, Almería, Spain
| | | | | | | | - Antonio F Hernández
- Dept. Legal Medicine and Toxicology, University of Granada School of Medicine, Granada, Spain
| | - Raquel Alarcón
- University of Almería School of Health Sciences, Almería, Spain
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18
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Krishnan JK, Figueiredo TH, Moffett JR, Arun P, Appu AP, Puthillathu N, Braga MF, Flagg T, Namboodiri AM. Brief isoflurane administration as a post-exposure treatment for organophosphate poisoning. Neurotoxicology 2017; 63:84-89. [DOI: 10.1016/j.neuro.2017.09.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Revised: 07/19/2017] [Accepted: 09/18/2017] [Indexed: 10/18/2022]
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19
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Hobson BA, Rowland DJ, Supasai S, Harvey DJ, Lein PJ, Garbow JR. A magnetic resonance imaging study of early brain injury in a rat model of acute DFP intoxication. Neurotoxicology 2017; 66:170-178. [PMID: 29183789 DOI: 10.1016/j.neuro.2017.11.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 11/21/2017] [Accepted: 11/24/2017] [Indexed: 11/18/2022]
Abstract
Current treatments for seizures induced by organophosphates do not protect sufficiently against progressive neurodegeneration or delayed cognitive impairment. Developing more effective therapeutic approaches has been challenging because the pathogenesis of these delayed consequences is poorly defined. Using magnetic resonance imaging (MRI), we previously reported brain lesions that persist for months in a rat model of acute intoxication with the OP, diisopropylfluorophosphate (DFP). However, the early spatiotemporal progression of these lesions remains unknown. To address this data gap, we used in vivo MRI to longitudinally monitor brain lesions during the first 3 d following acute DFP intoxication. Adult male Sprague Dawley rats acutely intoxicated with DFP (4mg/kg, sc) were MR imaged at 6, 12, 18, 24, 48, 72h post-DFP, and their brains then taken for correlative histology to assess neurodegeneration using FluoroJade C (FJC) staining. Acute DFP intoxication elicited moderate-to-severe seizure activity. T2-weighted (T2w) anatomic imaging revealed prominent lesions within the thalamus, piriform cortex, cerebral cortex, hippocampus, corpus striatum, and substantia nigra that corresponded to neurodegeneration, evident as bands of FJC positive cells. Semi-quantitative assessment of lesion severity demonstrated significant regional variation in the onset and progression of injury, and suggested that lesion severity may be modulated by isoflurane anesthesia. These results imply that the timing of therapeutic intervention for attenuating brain injury following OP intoxication may be regionally dependent, and that longitudinal assessment of OP-induced damage by MRI may be a powerful tool for assessing therapeutic response.
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Affiliation(s)
- Brad A Hobson
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA, 95616, United States.
| | - Douglas J Rowland
- Center for Molecular and Genomic Imaging, University of California, Davis, College of Engineering, Davis, CA, 95616, United States.
| | - Suangsuda Supasai
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA, 95616, United States.
| | - Danielle J Harvey
- Department of Public Health Sciences, University of California, Davis, School of Medicine, Davis, CA, 95616, United States.
| | - Pamela J Lein
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA, 95616, United States.
| | - Joel R Garbow
- Biomedical Magnetic Resonance Laboratory, Mallinckrodt Institute of Radiology, School of Medicine,Washington University in St. Louis, St. Louis, MO, 63110, United States.
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20
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Hobson BA, Sisó S, Rowland DJ, Harvey DJ, Bruun DA, Garbow JR, Lein PJ. From the Cover: MagneticResonance Imaging Reveals Progressive Brain Injury in Rats Acutely Intoxicated With Diisopropylfluorophosphate. Toxicol Sci 2017; 157:342-353. [PMID: 28329842 PMCID: PMC5458789 DOI: 10.1093/toxsci/kfx049] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Acute intoxication with organophosphates (OPs) can trigger seizures that progress to status epilepticus, and survivors often exhibit chronic neuropathology, cognitive impairment, affective disorders, and/or electroencephalographic abnormalities. Understanding how acute injury transitions to persistent neurological sequelae is critical to developing medical countermeasures for mitigating damage following OP-induced seizures. Here, we used in vivo magnetic resonance imaging (MRI) to monitor the spatiotemporal patterns of neuropathology for 1 month after acute intoxication with diisopropylfluorophosphate (DFP). Adult male Sprague Dawley rats administered pyridostigmine bromide (0.1 mg/kg, im) 30 min prior to successive administration of DFP (4 mg/kg, sc), atropine sulfate (2 mg/kg, im), and 2-pralidoxime (25 mg/kg, im) exhibited moderate-to-severe seizure behavior. T2-weighted and diffusion-weighted MR imaging prior to DFP exposure and at 3, 7, 14, 21, or 28 days postexposure revealed prominent lesions, tissue atrophy, and ventricular enlargement in discrete brain regions. Lesions varied in intensity and/or extent over time, with the overall magnitude of injury strongly influenced by seizure severity. Importantly, lesions detected by MRI correlated spatially and temporally with histological evidence of brain pathology. Analysis of histogram parameters extracted from frequency distributions of regional apparent diffusion coefficient (ADC) values identified the standard deviation and 90th percentile of the ADC as robust metrics for quantifying persistent and progressive neuropathological changes. The interanimal and interregional variations observed in lesion severity and progression, coupled with potential reinjury following spontaneous recurrent seizures, underscore the advantages of using in vivo imaging to longitudinally monitor neuropathology and, ultimately, therapeutic response, following acute OP intoxication.
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Affiliation(s)
- Brad A. Hobson
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California-Davis, Davis, California 95616
| | - Sílvia Sisó
- Translational Biology in the Department of Research, BioMarin Pharmaceuticals Inc, Novato, California 94949
| | - Douglas J. Rowland
- Department of Biomedical Engineering and the Center for Molecular and Genomic Imaging College of Engineering
| | - Danielle J. Harvey
- Department of Public Health Sciences School of Medicine, University of California-Davis, Davis, California 95616
| | - Donald A. Bruun
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California-Davis, Davis, California 95616
| | - Joel R. Garbow
- Biomedical Magnetic Resonance Laboratory, Mallinckrodt Institute of Radiology, School of Medicine, Washington University in St. Louis, St. Louis, Missouri 63110
| | - Pamela J. Lein
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California-Davis, Davis, California 95616
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21
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Effect of administration method, animal weight and age on the intranasal delivery of drugs to the brain. J Neurosci Methods 2017; 286:16-21. [PMID: 28499841 DOI: 10.1016/j.jneumeth.2017.05.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 04/22/2017] [Accepted: 05/07/2017] [Indexed: 01/20/2023]
Abstract
BACKGROUND The intranasal route of administration has proven to be an effective method for bypassing the blood brain barrier and avoiding first pass hepatic metabolism when targeting drugs to the brain. Most small molecules gain rapid access to CNS parenchyma when administered intranasally. However, bioavailability is affected by various factors ranging from the molecular weight of the drug to the mode of intranasal delivery. COMPARISON WITH EXISTING METHODS We examined the effects of animal posture, intranasal application method and animal weight and age on the delivery of radiolabeled pralidoxime (3H-2-PAM) to the brain of rats. RESULTS We found that using upright vs. supine posture did not significantly affect 3H-2-PAM concentrations in different brain regions. Older animals with higher weights required increased doses to achieve the same drug concentration throughout the brain when compared to young animals with lower body weights. The use of an intranasal aerosol propelled delivery device mainly increased bioavailability in the olfactory bulbs, but did not reliably increase delivery of the drug to various other brain regions, and in some regions of the brain delivered less of the drug than simple pipette administration. CONCLUSION In view of the emerging interest in the use of intranasal delivery of drugs to combat cognitive decline in old age, we tested effectiveness in very old rats and found the method to be as effective in the older rats.
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22
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Flannery BM, Bruun DA, Rowland DJ, Banks CN, Austin AT, Kukis DL, Li Y, Ford BD, Tancredi DJ, Silverman JL, Cherry SR, Lein PJ. Persistent neuroinflammation and cognitive impairment in a rat model of acute diisopropylfluorophosphate intoxication. J Neuroinflammation 2016; 13:267. [PMID: 27733171 PMCID: PMC5062885 DOI: 10.1186/s12974-016-0744-y] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 10/06/2016] [Indexed: 12/19/2022] Open
Abstract
Background Acute intoxication with organophosphorus (OP) cholinesterase inhibitors can trigger convulsions that progress to life-threatening status epilepticus. Survivors face long-term morbidity including mild-to-severe decline in memory. It is posited that neuroinflammation plays a key role in the pathogenesis of OP-induced neuropsychiatric deficits. Rigorous testing of this hypothesis requires preclinical models that recapitulate relevant phenotypic outcomes. Here, we describe a rat model of acute intoxication with the OP diisopropylfluorophosphate (DFP) that exhibits persistent neuroinflammation and cognitive impairment. Methods Neuroinflammation, neurodegeneration, and cognitive function were compared in adult male Sprague Dawley rats injected with an acutely toxic dose of DFP vs. vehicle controls at multiple time points up to 36 days post-exposure. Neuroinflammation was quantified using immunohistochemical biomarkers of microglia (ionized calcium-binding adapter molecule 1, IBA1) and activated astrocytes (glial fibrillary acidic protein, GFAP) and positron emission tomography (PET) imaging of [11C]-(R)-PK11195, a ligand for the 18-kDa mitochondrial membrane translocator protein (TSPO). FluoroJade-B staining was used to assess neurodegeneration; Pavlovian conditioning, to assess cognitive function. Results Animals exhibited moderate-to-severe seizures within minutes of DFP injection that continued for up to 6 h post-injection. As indicated by IBA1 and GFAP immunoreactivity and by PET imaging of TSPO, acute DFP intoxication triggered neuroinflammation in the hippocampus and cortex during the first 3 days that peaked at 7 days and persisted to 21 days post-exposure in most animals. Neurodegeneration was detected in multiple brain regions from 1 to 14 days post-exposure. All DFP-intoxicated animals exhibited significant deficits in contextual fear conditioning at 9 and 20 days post-exposure compared to vehicle controls. Whole-brain TSPO labeling positively correlated with seizure severity score, but did not correlate with performance in the contextual fear-conditioning task. Conclusions We describe a preclinical model in which acute DFP intoxication causes seizures, persistent neuroinflammation, neurodegeneration, and memory impairment. The extent of the neuroinflammatory response is influenced by seizure severity. However, the observation that a subset of animals with moderate seizures and minimal TSPO labeling exhibited cognitive deficits comparable to those of animals with severe seizures and significant TSPO labeling suggests that DFP may impair learning and memory circuitry via mechanisms independent of seizures or neuroinflammation.
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Affiliation(s)
- Brenna M Flannery
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, 95616, USA
| | - Donald A Bruun
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, 95616, USA
| | - Douglas J Rowland
- Center for Molecular and Genomic Imaging, University of California-Davis, Davis, CA, 95616, USA
| | - Christopher N Banks
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, 95616, USA.,Current address: Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, Sacramento, CA, 95812, USA
| | - Adam T Austin
- Department of Pediatrics, University of California-Davis Medical Center, Sacramento, CA, 95817, USA.,Current address: Navistar, Inc., 2701 Navistar Drive, Lisle, IL, 60532, USA
| | - David L Kukis
- Center for Molecular and Genomic Imaging, University of California-Davis, Davis, CA, 95616, USA
| | - Yonggang Li
- Division of Biomedical Sciences, University of California-Riverside School of Medicine, Riverside, CA, 92521, USA
| | - Byron D Ford
- Division of Biomedical Sciences, University of California-Riverside School of Medicine, Riverside, CA, 92521, USA
| | - Daniel J Tancredi
- Department of Pediatrics, University of California-Davis Medical Center, Sacramento, CA, 95817, USA
| | - Jill L Silverman
- Department of Psychiatry and Behavioral Sciences, University of California-Davis Medical Center, Sacramento, CA, 95817, USA
| | - Simon R Cherry
- Center for Molecular and Genomic Imaging, University of California-Davis, Davis, CA, 95616, USA
| | - Pamela J Lein
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, 95616, USA.
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23
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Krishnan JKS, Arun P, Appu AP, Vijayakumar N, Figueiredo TH, Braga MFM, Baskota S, Olsen CH, Farkas N, Dagata J, Frey WH, Moffett JR, Namboodiri AMA. Intranasal delivery of obidoxime to the brain prevents mortality and CNS damage from organophosphate poisoning. Neurotoxicology 2016; 53:64-73. [PMID: 26751814 DOI: 10.1016/j.neuro.2015.12.020] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Revised: 12/28/2015] [Accepted: 12/29/2015] [Indexed: 01/08/2023]
Abstract
Intranasal delivery is an emerging method for bypassing the blood brain barrier (BBB) and targeting therapeutics to the CNS. Oximes are used to counteract the effects of organophosphate poisoning, but they do not readily cross the BBB. Therefore, they cannot effectively counteract the central neuropathologies caused by cholinergic over-activation when administered peripherally. For these reasons we examined intranasal administration of oximes in an animal model of severe organophosphate poisoning to determine their effectiveness in reducing mortality and seizure-induced neuronal degeneration. Using the paraoxon model of organophosphate poisoning, we administered the standard treatment (intramuscular pralidoxime plus atropine sulphate) to all animals and then compared the effectiveness of intranasal application of obidoxime (OBD) to saline in the control groups. Intranasally administered OBD was effective in partially reducing paraoxon-induced acetylcholinesterase inhibition in the brain and substantially reduced seizure severity and duration. Further, intranasal OBD completely prevented mortality, which was 41% in the animals given standard treatment plus intranasal saline. Fluoro-Jade-B staining revealed extensive neuronal degeneration in the surviving saline-treated animals 24h after paraoxon administration, whereas no detectable degenerating neurons were observed in any of the animals given intranasal OBD 30min before or 5min after paraoxon administration. These findings demonstrate that intranasally administered oximes bypass the BBB more effectively than those administered peripherally and provide an effective method for protecting the brain from organophosphates. The addition of intranasally administered oximes to the current treatment regimen for organophosphate poisoning would improve efficacy, reducing both brain damage and mortality.
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Affiliation(s)
- Jishnu K S Krishnan
- Department of Anatomy, Physiology and Genetics, and Neurosciences Program, USUHS, Bethesda, 20814 MD, United States
| | - Peethambaran Arun
- Department of Anatomy, Physiology and Genetics, and Neurosciences Program, USUHS, Bethesda, 20814 MD, United States
| | - Abhilash P Appu
- Department of Anatomy, Physiology and Genetics, and Neurosciences Program, USUHS, Bethesda, 20814 MD, United States
| | - Nivetha Vijayakumar
- Department of Anatomy, Physiology and Genetics, and Neurosciences Program, USUHS, Bethesda, 20814 MD, United States
| | - Taíza H Figueiredo
- Department of Anatomy, Physiology and Genetics, and Neurosciences Program, USUHS, Bethesda, 20814 MD, United States
| | - Maria F M Braga
- Department of Anatomy, Physiology and Genetics, and Neurosciences Program, USUHS, Bethesda, 20814 MD, United States
| | - Sudikshya Baskota
- Department of Anatomy, Physiology and Genetics, and Neurosciences Program, USUHS, Bethesda, 20814 MD, United States
| | - Cara H Olsen
- Biostatistics Consulting Center, USUHS Bethesda, MD, United States
| | - Natalia Farkas
- Section on Metrology, NIST, Gaithersburg, MD, United States
| | - John Dagata
- Section on Metrology, NIST, Gaithersburg, MD, United States
| | - William H Frey
- Center for Memory & Aging, Regions Hospital, Health Partners Institute for Education and Research, St. Paul, MN, United States
| | - John R Moffett
- Department of Anatomy, Physiology and Genetics, and Neurosciences Program, USUHS, Bethesda, 20814 MD, United States
| | - Aryan M A Namboodiri
- Department of Anatomy, Physiology and Genetics, and Neurosciences Program, USUHS, Bethesda, 20814 MD, United States.
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Rojas A, Ganesh T, Lelutiu N, Gueorguieva P, Dingledine R. Inhibition of the prostaglandin EP2 receptor is neuroprotective and accelerates functional recovery in a rat model of organophosphorus induced status epilepticus. Neuropharmacology 2015; 93:15-27. [PMID: 25656476 PMCID: PMC4387070 DOI: 10.1016/j.neuropharm.2015.01.017] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 01/20/2015] [Accepted: 01/22/2015] [Indexed: 11/20/2022]
Abstract
Exposure to high levels of organophosphorus compounds (OP) can induce status epilepticus (SE) in humans and rodents via acute cholinergic toxicity, leading to neurodegeneration and brain inflammation. Currently there is no treatment to combat the neuropathologies associated with OP exposure. We recently demonstrated that inhibition of the EP2 receptor for PGE2 reduces neuronal injury in mice following pilocarpine-induced SE. Here, we investigated the therapeutic effects of an EP2 inhibitor (TG6-10-1) in a rat model of SE using diisopropyl fluorophosphate (DFP). We tested the hypothesis that EP2 receptor inhibition initiated well after the onset of DFP-induced SE reduces the associated neuropathologies. Adult male Sprague-Dawley rats were injected with pyridostigmine bromide (0.1 mg/kg, sc) and atropine methylbromide (20 mg/kg, sc) followed by DFP (9.5 mg/kg, ip) to induce SE. DFP administration resulted in prolonged upregulation of COX-2. The rats were administered TG6-10-1 or vehicle (ip) at various time points relative to DFP exposure. Treatment with TG6-10-1 or vehicle did not alter the observed behavioral seizures, however six doses of TG6-10-1 starting 80-150 min after the onset of DFP-induced SE significantly reduced neurodegeneration in the hippocampus, blunted the inflammatory cytokine burst, reduced microglial activation and decreased weight loss in the days after status epilepticus. By contrast, astrogliosis was unaffected by EP2 inhibition 4 d after DFP. Transient treatments with the EP2 antagonist 1 h before DFP, or beginning 4 h after DFP, were ineffective. Delayed mortality, which was low (10%) after DFP, was unaffected by TG6-10-1. Thus, selective inhibition of the EP2 receptor within a time window that coincides with the induction of cyclooxygenase-2 by DFP is neuroprotective and accelerates functional recovery of rats.
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Affiliation(s)
- Asheebo Rojas
- Department of Pharmacology, Emory University, 1510 Clifton Road NE, Atlanta, GA 30322, USA.
| | - Thota Ganesh
- Department of Pharmacology, Emory University, 1510 Clifton Road NE, Atlanta, GA 30322, USA
| | - Nadia Lelutiu
- Department of Pharmacology, Emory University, 1510 Clifton Road NE, Atlanta, GA 30322, USA
| | - Paoula Gueorguieva
- Department of Pharmacology, Emory University, 1510 Clifton Road NE, Atlanta, GA 30322, USA
| | - Raymond Dingledine
- Department of Pharmacology, Emory University, 1510 Clifton Road NE, Atlanta, GA 30322, USA
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Li Y, Lein PJ, Ford GD, Liu C, Stovall KC, White TE, Bruun DA, Tewolde T, Gates AS, Distel TJ, Surles-Zeigler MC, Ford BD. Neuregulin-1 inhibits neuroinflammatory responses in a rat model of organophosphate-nerve agent-induced delayed neuronal injury. J Neuroinflammation 2015; 12:64. [PMID: 25880399 PMCID: PMC4391606 DOI: 10.1186/s12974-015-0283-y] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 03/17/2015] [Indexed: 11/24/2022] Open
Abstract
Background Neuregulin-1 (NRG-1) has been shown to act as a neuroprotectant in animal models of nerve agent intoxication and other acute brain injuries. We recently demonstrated that NRG-1 blocked delayed neuronal death in rats intoxicated with the organophosphate (OP) neurotoxin diisopropylflurophosphate (DFP). It has been proposed that inflammatory mediators are involved in the pathogenesis of OP neurotoxin-mediated brain damage. Methods We examined the influence of NRG-1 on inflammatory responses in the rat brain following DFP intoxication. Microglial activation was determined by immunohistchemistry using anti-CD11b and anti-ED1 antibodies. Gene expression profiling was performed with brain tissues using Affymetrix gene arrays and analyzed using the Ingenuity Pathway Analysis software. Cytokine mRNA levels following DFP and NRG-1 treatment was validated by real-time reverse transcription polymerase chain reaction (RT-PCR). Results DFP administration resulted in microglial activation in multiple brain regions, and this response was suppressed by treatment with NRG-1. Using microarray gene expression profiling, we observed that DFP increased mRNA levels of approximately 1,300 genes in the hippocampus 24 h after administration. NRG-1 treatment suppressed by 50% or more a small fraction of DFP-induced genes, which were primarily associated with inflammatory responses. Real-time RT-PCR confirmed that the mRNAs for pro-inflammatory cytokines interleukin-1β (IL-1β) and interleukin-6 (IL-6) were significantly increased following DFP exposure and that NRG-1 significantly attenuated this transcriptional response. In contrast, tumor necrosis factor α (TNFα) transcript levels were unchanged in both DFP and DFP + NRG-1 treated brains relative to controls. Conclusion Neuroprotection by NRG-1 against OP neurotoxicity is associated with the suppression of pro-inflammatory responses in brain microglia. These findings provide new insight regarding the molecular mechanisms involved in the neuroprotective role of NRG-1 in acute brain injuries.
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Affiliation(s)
- Yonggang Li
- Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, 720 Westview Drive, SW, Atlanta, GA, 30310, USA.
| | - Pamela J Lein
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, 1089 Veterinary Medicine Drive, Davis, CA, 95616, USA.
| | - Gregory D Ford
- Department of Biology, Morehouse College, 830 Westview Drive SW, Atlanta, GA, 30310, USA.
| | - Cuimei Liu
- Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, 720 Westview Drive, SW, Atlanta, GA, 30310, USA. .,Institute of Infectious Disease, Xiangya Hospital, Central-South University, No.9 Chegongzhuang Avenue, Changsha, 100044, China.
| | - Kyndra C Stovall
- Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, 720 Westview Drive, SW, Atlanta, GA, 30310, USA. .,Department of Biology, Morehouse College, 830 Westview Drive SW, Atlanta, GA, 30310, USA. .,Department of Physiology, Emory University, 201 Dowman Dr., Atlanta, GA, 30322, USA.
| | - Todd E White
- Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, 720 Westview Drive, SW, Atlanta, GA, 30310, USA.
| | - Donald A Bruun
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, 1089 Veterinary Medicine Drive, Davis, CA, 95616, USA.
| | - Teclemichael Tewolde
- Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, 720 Westview Drive, SW, Atlanta, GA, 30310, USA.
| | - Alicia S Gates
- Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, 720 Westview Drive, SW, Atlanta, GA, 30310, USA.
| | - Timothy J Distel
- Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, 720 Westview Drive, SW, Atlanta, GA, 30310, USA.
| | - Monique C Surles-Zeigler
- Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, 720 Westview Drive, SW, Atlanta, GA, 30310, USA.
| | - Byron D Ford
- Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, 720 Westview Drive, SW, Atlanta, GA, 30310, USA.
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Li Y, Lein PJ, Liu C, Bruun DA, Giulivi C, Ford GD, Tewolde T, Ross-Inta C, Ford BD. Neuregulin-1 is neuroprotective in a rat model of organophosphate-induced delayed neuronal injury. Toxicol Appl Pharmacol 2012; 262:194-204. [PMID: 22583949 DOI: 10.1016/j.taap.2012.05.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 04/30/2012] [Accepted: 05/03/2012] [Indexed: 02/02/2023]
Abstract
Current medical countermeasures against organophosphate (OP) nerve agents are effective in reducing mortality, but do not sufficiently protect the CNS from delayed brain damage and persistent neurological symptoms. In this study, we examined the efficacy of neuregulin-1 (NRG-1) in protecting against delayed neuronal cell death following acute intoxication with the OP diisopropylflurophosphate (DFP). Adult male Sprague-Dawley rats were pretreated with pyridostigmine (0.1 mg/kg BW, i.m.) and atropine methylnitrate (20 mg/kg BW, i.m.) prior to DFP (9 mg/kg BW, i.p.) intoxication to increase survival and reduce peripheral signs of cholinergic toxicity but not prevent DFP-induced seizures or delayed neuronal injury. Pretreatment with NRG-1 did not protect against seizures in rats exposed to DFP. However, neuronal injury was significantly reduced in most brain regions by pretreatment with NRG-1 isoforms NRG-EGF (3.2 μg/kg BW, i.a) or NRG-GGF2 (48 μg/kg BW, i.a.) as determined by FluroJade-B labeling in multiple brain regions at 24 h post-DFP injection. NRG-1 also blocked apoptosis and oxidative stress-mediated protein damage in the brains of DFP-intoxicated rats. Administration of NRG-1 at 1h after DFP injection similarly provided significant neuroprotection against delayed neuronal injury. These findings identify NRG-1 as a promising adjuvant therapy to current medical countermeasures for enhancing neuroprotection against acute OP intoxication.
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Affiliation(s)
- Yonggang Li
- Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA
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Chen Y. Organophosphate-induced brain damage: mechanisms, neuropsychiatric and neurological consequences, and potential therapeutic strategies. Neurotoxicology 2012; 33:391-400. [PMID: 22498093 DOI: 10.1016/j.neuro.2012.03.011] [Citation(s) in RCA: 154] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 03/24/2012] [Accepted: 03/25/2012] [Indexed: 02/06/2023]
Abstract
Organophosphate (OP)-induced brain damage is defined as progressive damage to the brain, resulting from the cholinergic neuronal excitotoxicity and dysfunction induced by OP-induced irreversible AChE inhibition. This delayed secondary neuronal damage that occurs mainly in the cholinergic regions of the brain that contain dense accumulations of cholinergic neurons and the majority of cholinergic projection, might be largely responsible for persistent profound neuropsychiatric and neurological impairments (memory, cognitive, mental, emotional, motor and sensory deficits) in the victims of OP poisoning. Neuroprotective strategies for attenuating OP-induced brain damage should target different development stages of OP-induced brain damage, and may include but not limited to: (1) Antidote therapies with atropine and related efficient anticholinergic drugs; (2) Anti-excitotoxic therapies targeting attenuation of cerebral edema and inflammatory reaction, blockage of calcium influx, inhibition of apoptosis program, and the control of seizures; (3) Neuroprotective strategies using cytokines, antioxidants and NMDAR antagonists (a single drug or a combination of drugs) to slow down the process of secondary neuronal damage; and (4) Therapies targeting individual symptoms or clusters of chronic neuropsychiatric and neurological symptoms. These neuroprotective strategies may help limit or prevent secondary neuronal damage at the early stage of OP poisoning and attenuate the subsequent neuropsychiatric and neurological impairments, thus reducing the long-term disability caused by exposure to OPs.
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Affiliation(s)
- Yun Chen
- BrightstarTech, Inc., 23102 Meadow Mist Road, Clarksburg, MD 20871, USA.
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Li Y, Lein PJ, Liu C, Bruun DA, Tewolde T, Ford G, Ford BD. Spatiotemporal pattern of neuronal injury induced by DFP in rats: a model for delayed neuronal cell death following acute OP intoxication. Toxicol Appl Pharmacol 2011; 253:261-9. [PMID: 21513723 DOI: 10.1016/j.taap.2011.03.026] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 03/25/2011] [Accepted: 03/31/2011] [Indexed: 01/16/2023]
Abstract
Organophosphate (OP) neurotoxins cause acute cholinergic toxicity and seizures resulting in delayed brain damage and persistent neurological symptoms. Testing novel strategies for protecting against delayed effects of acute OP intoxication has been hampered by the lack of appropriate animal models. In this study, we characterize the spatiotemporal pattern of cellular injury after acute intoxication with the OP diisopropylfluorophosphate (DFP). Adult male Sprague-Dawley rats received pyridostigmine (0.1 mg/kg, im) and atropine methylnitrate (20mg/kg, im) prior to DFP (9 mg/kg, ip) administration. All DFP-treated animals exhibited moderate to severe seizures within minutes after DFP injection but survived up to 72 h. AChE activity was significantly depressed in the cortex, hippocampus, subcortical brain tissue and cerebellum at 1h post-DFP injection and this inhibition persisted for up to 72 h. Analysis of neuronal injury by Fluoro-Jade B (FJB) labeling revealed delayed neuronal cell death in the hippocampus, cortex, amygdala and thalamus, but not the cerebellum, starting at 4h and persisting until 72 h after DFP treatment, although temporal profiles varied between brain regions. At 24h post-DFP injection, the pattern of FJB labeling corresponded to TUNEL staining in most brain regions, and FJB-positive cells displayed reduced NeuN immunoreactivity but were not immunopositive for astrocytic (GFAP), oligodendroglial (O4) or macrophage/microglial (ED1) markers, demonstrating that DFP causes a region-specific delayed neuronal injury mediated in part by apoptosis. These findings indicate the feasibility of this model for testing neuroprotective strategies, and provide insight regarding therapeutic windows for effective pharmacological intervention following acute OP intoxication.
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Affiliation(s)
- Yonggang Li
- Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA
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Ghanei M, Naderi M, Kosar AM, Harandi AA, Hopkinson NS, Poursaleh Z. Long-term pulmonary complications of chemical warfare agent exposure in Iraqi Kurdish civilians. Inhal Toxicol 2010; 22:719-24. [PMID: 20560732 DOI: 10.3109/08958371003686016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The Iraqi government used a range of chemical weapons, including blistering and nerve agents, against Iraqi Kurdish civilians in the 1980s. Few data exist about the long-term respiratory consequences of this exposure. In this study, Kurdish subjects with a history of exposure to chemical weapons were invited to attend a clinical assessment, including a review of their history, physical examination, and a high-resolution computed tomography (CT) of the thorax. Blistering at the time of exposure was used to define significant exposure to mustard gas. Results were compared between two groups of blistering and nonblistering. Four hundred seventy-nine subjects were studied; 45.7% male and 54.3% female. The mean age and standard deviation (mean +/- SD) of the cases was 43.1 +/- 13.7. Spirometry was abnormal in 15.2% of subjects and air trapping was present on CT scan in 46.6% and did not differ between patients with (n = 278) or without a history of blistering. Respiratory symptoms, including dyspnea, cough, and sputum production, were more common in subjects with a history of blistering (all p < .005) and blistering was also associated with a lower forced expiratory volume in one second (FEV(1)) (p < .0001). Severe complications were most common in subjects from Halabja who also made up the majority of participants. These results show that objective abnormalities are common in people with symptoms attributed to prior exposure to chemical agent. Blistering at the time of exposure was associated with more respiratory symptoms and worse lung function, but not with CT appearances. The high proportion of severe cases in comparison to reports from Iran may reflect the historical absence of effective early treatment, including strategies to reduce prolonged early exposure in this population.
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Affiliation(s)
- Mostafa Ghanei
- Research Center of Chemical Injuries, Baqiyatallah University of Medical Sciences, Tehran, Iran.
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Verma SK, Raheja G, Gill KD. Role of muscarinic signal transduction and CREB phosphorylation in dichlorvos-induced memory deficits in rats: an acetylcholine independent mechanism. Toxicology 2008; 256:175-82. [PMID: 19100812 DOI: 10.1016/j.tox.2008.11.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2008] [Revised: 11/05/2008] [Accepted: 11/18/2008] [Indexed: 11/17/2022]
Abstract
The present study was designed to explore the alternative mechanism (other than AChE inhibition) for chronic, low-level exposure to dichlorvos, an organophosphate, in vivo. Dichlorvos, at a dose of 1.0 and 6.0 mg/kg body weight (b.wt.) for 12 weeks, showed impairment in neurobehavioral indices viz. rota rod, passive avoidance and water maze tests. Though high dose of dichlorvos had a detrimental effect on acetylcholinesterase activity, no significant inhibition was seen with low dose of dichlorvos. Western blot analysis and immunofluorescence studies showed a significant reduction in the expression of M(1), M(2) and M(3) muscarinic receptor subtypes in high dose group animals, whereas in low dose group animals only the M(2) receptor subtype was reduced significantly. Further, the signal transduction cascade linked to these receptor subtypes was affected in high dose group animals whereas in low dose group only adenylyl cyclase-linked signaling pathway was impaired. Finally, the phosphorylation of CREB, a memory enhancing transcription factor, was significantly reduced in both low dose and high dose group animals. Thus, the present study reveals the significance of M(2) muscarinic receptor linked adenylyl cyclase signaling pathway and phosphorylation of CREB in the development of neurobehavioral impairments after chronic low-level exposure to dichlorvos.
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Affiliation(s)
- Suresh Kumar Verma
- Department of Biochemistry, Postgraduate Institute of Medical Education and Research, Chandigarh 160 012, India
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