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Wigenstam E, Forsberg E, Bucht A, Thors L. Efficacy of atropine and scopolamine on airway contractions following exposure to the nerve agent VX. Toxicol Appl Pharmacol 2021; 419:115512. [PMID: 33785355 DOI: 10.1016/j.taap.2021.115512] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 03/10/2021] [Accepted: 03/25/2021] [Indexed: 11/25/2022]
Abstract
Nerve agents are highly toxic organophosphorus compounds that inhibit acetylcholinesterase resulting in rapid accumulation of the neurotransmitter acetylcholine (ACh) causing a cholinergic syndrome including respiratory failure. In the present study, respiratory responses and antimuscarinic treatment efficacy was evaluated ex vivo using rat precision-cut lung slices (PCLS) exposed to the nerve agent VX. The respiratory effects were evaluated either by adding exogenous ACh directly to the culture medium or by applying electric-field stimulation (EFS) to the PCLS to achieve a release of endogenous ACh from neurons in the lung tissue. The airway contraction induced by both methods was enhanced by VX and resulted in lingering airway recovery, in particular when airways were exposed to a high VX-dose. Both contractions induced by EFS and exogenously added ACh were significantly reduced by administration of the antimuscarinic drugs atropine or scopolamine. Two additions of atropine or scopolamine after maximal ACh-induced airway response was demonstrated effective to reverse the contraction. By adding consecutive doubled doses of antimuscarinics, high efficiency to reduce the cholinergic airway response was observed. However, the airways were not completely recovered by atropine or scopolamine, indicating that non-muscarinic mechanisms were involved in the smooth muscle contractions. In conclusion, it was demonstrated that antimuscarinic treatment reversed airway contraction induced by VX but supplemental pharmacological interventions are needed to fully recover the airways. Further studies should therefore clarify the mechanisms of physiological responses in lung tissue following nerve agent exposures to improve the medical management of poisoned individuals.
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Affiliation(s)
- E Wigenstam
- Swedish Defence Research Agency, CBRN Defence and Security, Umeå, Sweden
| | - E Forsberg
- Swedish Defence Research Agency, CBRN Defence and Security, Umeå, Sweden
| | - A Bucht
- Swedish Defence Research Agency, CBRN Defence and Security, Umeå, Sweden
| | - L Thors
- Swedish Defence Research Agency, CBRN Defence and Security, Umeå, Sweden.
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2
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Bloch-Shilderman E, Yacov G, Cohen L, Egoz I, Gutman H, Gez R, Rabinovitz I, Nili U. Repetitive antidotal treatment is crucial in eliminating eye pathology, respiratory toxicity and death following whole-body VX vapor exposure in freely moving rats. Arch Toxicol 2019; 93:1365-1384. [DOI: 10.1007/s00204-019-02401-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Accepted: 01/31/2019] [Indexed: 11/29/2022]
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3
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Bloch-Shilderman E, Rabinovitz I, Egoz I, Yacov G, Allon N, Nili U. Determining a threshold sub-acute dose leading to minimal physiological alterations following prolonged exposure to the nerve agent VX in rats. Arch Toxicol 2017; 92:873-892. [DOI: 10.1007/s00204-017-2108-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 10/26/2017] [Indexed: 10/18/2022]
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4
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Wright LKM, Lee RB, Clarkson ED, Lumley LA. Female rats are less susceptible during puberty to the lethal effects of percutaneous exposure to VX. Toxicol Rep 2015; 3:895-899. [PMID: 28959617 PMCID: PMC5615417 DOI: 10.1016/j.toxrep.2015.12.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 12/10/2015] [Accepted: 12/11/2015] [Indexed: 01/06/2023] Open
Abstract
Nerve agents with low volatility such as VX are primarily absorbed through the skin when released during combat or a terrorist attack. The barrier function of the stratum corneum may be compromised during certain stages of development, allowing VX to more easily penetrate through the skin. However, age-related differences in the lethal potency of VX have yet to be evaluated using the percutaneous (pc) route of exposure. Thus, we estimated the 24 and 48 h median lethal dose for pc exposure to VX in male and female rats during puberty and early adulthood. Pubescent, female rats were less susceptible than both their male and adult counterparts to the lethal effects associated with pc exposure to VX possibly because of hormonal changes during that stage of development. This study emphasizes the need to control for both age and sex when evaluating the toxicological effects associated with nerve agent exposure in the rat model.
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Key Words
- (AChE), acetylcholinesterase
- (ANOVA), analysis of variance
- (BARDA), Biomedical Advanced Research and Development Authority
- (CI), confidence interval
- (LD50), median lethal dose
- (PND), postnatal day
- (SC), subcutaneous or subcutaneously
- (TEWL), transepidermal water loss
- (USAMRICD), US Army Medical Research Institute of Chemical Defense
- (pc), percutaneous or percutaneously
- Median lethal dose
- Nerve agent
- Percutaneous
- Puberty
- Rat
- VX
- VX (PubChem CID: 39793)
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Affiliation(s)
- Linnzi K M Wright
- US Army Medical Research Institute of Chemical Defense, 2900 Ricketts Point Rd, Aberdeen Proving Ground, MD 21010, USA.,Edgewood Chemical Biological Center, 5183 Blackhawk Rd, Aberdeen Proving Ground, MD 21010, USA
| | - Robyn B Lee
- US Army Medical Research Institute of Chemical Defense, 2900 Ricketts Point Rd, Aberdeen Proving Ground, MD 21010, USA
| | - Edward D Clarkson
- US Army Medical Research Institute of Chemical Defense, 2900 Ricketts Point Rd, Aberdeen Proving Ground, MD 21010, USA
| | - Lucille A Lumley
- US Army Medical Research Institute of Chemical Defense, 2900 Ricketts Point Rd, Aberdeen Proving Ground, MD 21010, USA
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5
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Wright LKM, Lee RB, Vincelli NM, Whalley CE, Lumley LA. Comparison of the lethal effects of chemical warfare nerve agents across multiple ages. Toxicol Lett 2015; 241:167-74. [PMID: 26621540 DOI: 10.1016/j.toxlet.2015.11.023] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 11/09/2015] [Accepted: 11/21/2015] [Indexed: 12/17/2022]
Abstract
Children may be inherently more vulnerable than adults to the lethal effects associated with chemical warfare nerve agent (CWNA) exposure because of their closer proximity to the ground, smaller body mass, higher respiratory rate, increased skin permeability and immature metabolic systems. Unfortunately, there have only been a handful of studies on the effects of CWNA in pediatric animal models, and more research is needed to confirm this hypothesis. Using a stagewise, adaptive dose design, we estimated the 24h median lethal dose for subcutaneous exposure to seven CWNA in both male and female Sprague-Dawley rats at six different developmental times. Perinatal (postnatal day [PND] 7, 14 and 21) and adult (PND 70) rats were more susceptible than pubertal (PND 28 and 42) rats to the lethal effects associated with exposure to tabun, sarin, soman and cyclosarin. Age-related differences in susceptibility were not observed in rats exposed to VM, Russian VX or VX.
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Affiliation(s)
- Linnzi K M Wright
- US Army Medical Research Institute of Chemical Defense (USAMRICD), 2900 Ricketts Point Rd., Aberdeen Proving Ground, MD 21010, USA
| | - Robyn B Lee
- US Army Medical Research Institute of Chemical Defense (USAMRICD), 2900 Ricketts Point Rd., Aberdeen Proving Ground, MD 21010, USA
| | - Nicole M Vincelli
- Edgewood Chemical Biological Center (ECBC), 5183 Blackhawk Rd., Aberdeen Proving Ground, MD 21010, USA
| | - Christopher E Whalley
- Edgewood Chemical Biological Center (ECBC), 5183 Blackhawk Rd., Aberdeen Proving Ground, MD 21010, USA
| | - Lucille A Lumley
- US Army Medical Research Institute of Chemical Defense (USAMRICD), 2900 Ricketts Point Rd., Aberdeen Proving Ground, MD 21010, USA.
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6
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Smith CD, Wright LKM, Garcia GE, Lee RB, Lumley LA. Hormone-dependence of sarin lethality in rats: Sex differences and stage of the estrous cycle. Toxicol Appl Pharmacol 2015; 287:253-7. [PMID: 26079828 DOI: 10.1016/j.taap.2015.06.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 06/08/2015] [Accepted: 06/10/2015] [Indexed: 11/18/2022]
Abstract
Chemical warfare nerve agents (CWNAs) are highly toxic compounds that cause a cascade of symptoms and death, if exposed casualties are left untreated. Numerous rodent models have investigated the toxicity and mechanisms of toxicity of CWNAs, but most are limited to male subjects. Given the profound physiological effects of circulating gonadal hormones in female rodents, it is possible that the daily cyclical fluctuations of these hormones affect females' sensitivity to the lethal effects of CWNAs, and previous reports that included female subjects did not control for the stage of the hormonal cycle. The aim of the current study was to determine the 24-hour median lethal dose (LD50) of the CWNA sarin in male, ovariectomized (OVEX) female, and female rats during different stages of the estrous cycle (diestrus, proestrus, and estrus). Additionally, baseline activity levels of plasma acetylcholinesterase, butyrylcholinesterase, and carboxylesterase were measured to determine differences among the groups. Results indicated that females in proestrus had a significantly higher LD50 of sarin compared to OVEX and estrous females. Although some sex differences were observed in the activity levels of plasma esterases, they were not consistent and likely not large enough to significantly affect the LD50s. These results suggest that hormonal cyclicity can influence the outcome of CWNA-related studies using female rodents, and that this variability can be minimized by controlling for the stage of the cycle. Additional research is necessary to determine the precise mechanism of the observed differences because it is unlikely to be solely explained by plasma esterase activity.
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Affiliation(s)
- Carl D Smith
- US Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, MD 21010, United States.
| | - Linnzi K M Wright
- US Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, MD 21010, United States
| | - Gregory E Garcia
- US Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, MD 21010, United States
| | - Robyn B Lee
- US Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, MD 21010, United States
| | - Lucille A Lumley
- US Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, MD 21010, United States
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7
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Peng X, Perkins MW, Simons J, Witriol AM, Rodriguez AM, Benjamin BM, Devorak J, Sciuto AM. Acute pulmonary toxicity following inhalation exposure to aerosolized VX in anesthetized rats. Inhal Toxicol 2014; 26:371-9. [DOI: 10.3109/08958378.2014.899410] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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8
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Verma V, Yu QJ, Connell DW. Evaluation of effects of long term exposure on lethal toxicity with mammals. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2014; 185:234-239. [PMID: 24291612 DOI: 10.1016/j.envpol.2013.11.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 10/30/2013] [Accepted: 11/01/2013] [Indexed: 06/02/2023]
Abstract
The relationship between exposure time (LT50) and lethal exposure concentration (LC50) has been evaluated over relatively long exposure times using a novel parameter, Normal Life Expectancy (NLT), as a long term toxicity point. The model equation, ln(LT50) = aLC50(ν) + b, where a, b and ν are constants, was evaluated by plotting lnLT50 against LC50 using available toxicity data based on inhalation exposure from 7 species of mammals. With each specific toxicant a single consistent relationship was observed for all mammals with ν always <1. Use of NLT as a long term toxicity point provided a valuable limiting point for long exposure times. With organic compounds, the Kow can be used to calculate the model constants a and v where these are unknown. The model can be used to characterise toxicity to specific mammals and then be extended to estimate toxicity at any exposure time with other mammals.
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Affiliation(s)
- Vibha Verma
- Griffith School of Engineering, Griffith University, Nathan Campus, Brisbane, Queensland 4111, Australia.
| | - Qiming J Yu
- Griffith School of Engineering, Griffith University, Nathan Campus, Brisbane, Queensland 4111, Australia
| | - Des W Connell
- Griffith School of Environment, Griffith University, Nathan Campus, Brisbane, Queensland 4111, Australia
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9
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Wong B, Perkins MW, Santos MD, Rodriguez AM, Murphy G, Sciuto AM. Development of a model for nerve agent inhalation in conscious rats. Toxicol Mech Methods 2013; 23:537-47. [DOI: 10.3109/15376516.2013.796033] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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10
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Leppert J, Horner G, Rietz F, Ringer J, Schulze Lammers P, Boeker P. Near real time detection of hazardous airborne substances. Talanta 2012; 101:440-6. [DOI: 10.1016/j.talanta.2012.09.056] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Revised: 09/18/2012] [Accepted: 09/25/2012] [Indexed: 10/27/2022]
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11
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Schopfer LM, Lockridge O. Analytical approaches for monitoring exposure to organophosphorus and carbamate agents through analysis of protein adducts. Drug Test Anal 2012; 4:246-61. [DOI: 10.1002/dta.1325] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2011] [Revised: 09/29/2011] [Accepted: 10/02/2011] [Indexed: 12/16/2022]
Affiliation(s)
| | - Oksana Lockridge
- Eppley Institute; University of Nebraska Medical Center; Omaha; NE
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12
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A new methodology for estimating nerve agent (Sarin (GB)/VX) casualties as a function of time: Defining the Human Response Injury Profile nerve agent methodology. ACS CHEMICAL HEALTH & SAFETY 2011. [DOI: 10.1016/j.jchas.2010.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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13
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Watson A, Dolislager F, Hall L, Raber E, Hauschild VD, Love AH. Developing Health-Based Pre-Planning Clearance Goals for Airport Remediation Following a Chemical Terrorist Attack: Decision Criteria for Multipathway Exposure Routes. HUMAN AND ECOLOGICAL RISK ASSESSMENT : HERA 2011; 17:57-121. [PMID: 21399674 PMCID: PMC3046627 DOI: 10.1080/10807039.2010.534722] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2010] [Accepted: 07/20/2010] [Indexed: 05/04/2023]
Abstract
In the event of a chemical terrorist attack on a transportation hub, post-event remediation and restoration activities necessary to attain unrestricted facility re-use and re-entry could require hours to multiple days. While timeframes are dependent on numerous variables, a primary controlling factor is the level of pre-planning and decision-making completed prior to chemical release. What follows is the second of a two-part analysis identifying key considerations, critical information and decision criteria to facilitate post-attack and post-decontamination consequence management activities. Decision criteria analysis presented here provides first-time, open-literature documentation of multi-pathway, health-based remediation exposure guidelines for selected toxic industrial compounds, chemical warfare agents, and agent degradation products for pre-planning application in anticipation of a chemical terrorist attack. Guideline values are provided for inhalation and direct ocular vapor exposure routes as well as percutaneous vapor, surface contact, and ingestion. Target populations include various employees as well as transit passengers. This work has been performed as a national case study conducted in partnership with the Los Angeles International Airport and The Bradley International Terminal. All recommended guidelines have been selected for consistency with airport scenario release parameters of a one-time, short-duration, finite airborne release from a single source followed by compound-specific decontamination.
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Affiliation(s)
- Annetta Watson
- Toxicology and Hazard Assessment, Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | | | - Linda Hall
- Environmental Restoration Division, Lawrence Livermore National Laboratory, Livermore, CA, USA
- Current addresses: Linda Hall, ENVIRON International Corporation, Marketplace Tower, 6001 Shellmound St., Emeryville, CA 94608, USA; Adam H. Love, Johnson Wright Inc., 3730 Mt. Diablo Blvd., Lafayette, CA 94549, USA
| | - Ellen Raber
- Environmental Restoration Division, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Veronique D. Hauschild
- Directorate of Occupational and Environmental Medicine, U.S. Army Public Health Command (Provisional), Aberdeen Proving Ground, MD, USA
| | - Adam H. Love
- Environmental Restoration Division, Lawrence Livermore National Laboratory, Livermore, CA, USA
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14
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Watson A, Hall L, Raber E, Hauschild VD, Dolislager F, Love AH, Hanna ML. Developing Health-Based Pre-Planning Clearance Goals for Airport Remediation Following Chemical Terrorist Attack: Introduction and Key Assessment Considerations. HUMAN AND ECOLOGICAL RISK ASSESSMENT : HERA 2011; 17:2-56. [PMID: 21390292 PMCID: PMC3046625 DOI: 10.1080/10807039.2010.534721] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2010] [Accepted: 07/20/2010] [Indexed: 05/20/2023]
Abstract
In the event of a chemical terrorist attack on a transportation hub, post-event remediation and restoration activities necessary to attain unrestricted facility reuse and re-entry could require hours to multiple days. While restoration timeframes are dependent on numerous variables, a primary controlling factor is the level of pre-planning and decision-making completed prior to chemical terrorist release. What follows is the first of a two-part analysis identifying key considerations, critical information, and decision criteria to facilitate post-attack and post-decontamination consequence management activities. A conceptual site model and human health-based exposure guidelines are developed and reported as an aid to site-specific pre-planning in the current absence of U.S. state or Federal values designated as compound-specific remediation or re-entry concentrations, and to safely expedite facility recovery to full operational status. Chemicals of concern include chemical warfare nerve and vesicant agents and the toxic industrial compounds phosgene, hydrogen cyanide, and cyanogen chloride. This work has been performed as a national case study conducted in partnership with the Los Angeles International Airport and The Bradley International Terminal. All recommended guidelines have been selected for consistency with airport scenario release parameters of a one-time, short-duration, finite airborne release from a single source followed by compound-specific decontamination.
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Affiliation(s)
- Annetta Watson
- Toxicology and Hazard Assessment, Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
- ∗Address correspondence to Annetta Watson, Toxicology and Hazard Assessment, Environmental Sciences Division, Oak Ridge National Laboratory, 545 Oak Ridge Turnpike, Oak Ridge, TN 37830, USA. E-mail:
| | - Linda Hall
- Environmental Restoration Division, Lawrence Livermore National Laboratory, Livermore, CA, USA
- Current addresses: Linda Hall, ENVIRON International Corporation, Marketplace Tower, 6001 Shellmound St., Emeryville, CA 94608, USA; Adam H. Love, Johnson Wright Inc., 3730 Mt. Diablo Blvd., Lafayette, CA 94549, USA
| | - Ellen Raber
- Environmental Restoration Division, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | | | | | - Adam H. Love
- Environmental Restoration Division, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - M. Leslie Hanna
- Environmental Restoration Division, Lawrence Livermore National Laboratory, Livermore, CA, USA
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15
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Fawcett WP, Aracava Y, Adler M, Pereira EFR, Albuquerque EX. Acute toxicity of organophosphorus compounds in guinea pigs is sex- and age-dependent and cannot be solely accounted for by acetylcholinesterase inhibition. J Pharmacol Exp Ther 2008; 328:516-24. [PMID: 18984651 DOI: 10.1124/jpet.108.146639] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study was designed to test the hypothesis that the acute toxicity of the nerve agents S-[2-(diisopropylamino)ethyl]-O-ethyl methylphosphonothioate (VX), O-pinacolyl methylphosphonofluoridate (soman), and O-isopropyl methylphosphonofluoridate (sarin) in guinea pigs is age- and sex-dependent and cannot be fully accounted for by the irreversible inhibition of acetylcholinesterase (AChE). The subcutaneous doses of nerve agents needed to decrease 24-h survival of guinea pigs by 50% (LD(50) values) were estimated by probit analysis. In all animal groups, the rank order of LD(50) values was sarin > soman > VX. The LD(50) value of soman was not influenced by sex or age of the animals. In contrast, the LD(50) values of VX and sarin were lower in adult male than in age-matched female or younger guinea pigs. A colorimetric assay was used to determine the concentrations of nerve agents that inhibit in vitro 50% of AChE activity (IC(50) values) in guinea pig brain extracts, plasma, red blood cells, and whole blood. A positive correlation between LD(50) values and IC(50) values for AChE inhibition would support the hypothesis that AChE inhibition is a major determinant of the acute toxicity of the nerve agents. However, such a positive correlation was found only between LD(50) values and IC(50) values for AChE inhibition in brain extracts from neonatal and prepubertal guinea pigs. These results demonstrate for the first time that the lethal potencies of some nerve agents in guinea pigs are age- and sex-dependent. They also support the contention that mechanisms other than AChE inhibition contribute to the lethality of nerve agents.
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Affiliation(s)
- William P Fawcett
- Department of Pharmacology and Experimental Therapeutics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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16
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Bloch-Shilderman E, Rabinovitz I, Egoz I, Raveh L, Allon N, Grauer E, Gilat E, Weissman BA. Subchronic exposure to low-doses of the nerve agent VX: Physiological, behavioral, histopathological and neurochemical studies. Toxicol Appl Pharmacol 2008; 231:17-23. [DOI: 10.1016/j.taap.2008.03.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2007] [Revised: 03/19/2008] [Accepted: 03/31/2008] [Indexed: 11/25/2022]
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17
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Genovese RF, Benton BJ, Lee EH, Shippee SJ, Jakubowski EM. Behavioral and biochemical evaluation of sub-lethal inhalation exposure to VX in rats. Toxicology 2007; 232:109-18. [PMID: 17234319 DOI: 10.1016/j.tox.2006.12.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2006] [Revised: 12/04/2006] [Accepted: 12/15/2006] [Indexed: 11/16/2022]
Abstract
We evaluated the effects of low-level inhalation exposures (whole body, 60min duration) to the chemical warfare nerve agent VX (0.016, 0.15, 0.30 or 0.45mg/m(3)) in rats. The range of concentrations was approximately equivalent to 0.02-0.62 times 1.0 LC50. Biochemical effects were assessed by evaluating blood acetylcholinesterase (AChE) activity and by a regeneration assay that quantified the amount of VX (as the G analog) present in blood. Behavioral effects were assessed using a variable-interval 56-s schedule of reinforcement (VI56), in which rats were trained to press a lever to receive a food reward. VI56 training was established before exposure and evaluations continued after exposure. Additionally, after exposure, acquisition and maintenance of an eight-arm radial maze (RAM) task was evaluated in which rats learned to locate the four arms of the maze that presented a single food pellet reward. Behavioral assessments were conducted over approximately 3 months following exposure. Transient miosis was observed following exposure to all concentrations of VX and exposures to the 0.45mg/m(3) concentration also produced mild and temporary signs of toxicity (i.e., slight tremor and ataxia) in some subjects. All concentrations of VX also inhibited circulating AChE and the highest concentration inhibited AChE activity to less than 10% of pre-exposure values. Regenerated VX-G was found in red blood cell (RBC) and plasma blood fractions. In this respect, more VX-G was seen in plasma than RBC. Only small disruptions were observed on the VI56 or RAM following some VX exposures. In general, however, behavioral effects were minor and not clearly systematic. Taken together these results demonstrate that largely asymptomatic exposures to VX vapors in rats can produce substantial biochemical effects while having only minor performance effects on a previously learned behavioral task and on the acquisition of a new behavioral task.
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Affiliation(s)
- Raymond F Genovese
- Division of Psychiatry and Neurosciences, Walter Reed Army Institute of Research, Silver Spring, MD 20910-7500, USA.
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