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Sibomana I, Rohan JG, Mattie DR. 21-Day dermal exposure to aircraft engine oils: effects on esterase activities in brain and liver tissues, blood, plasma, and clinical chemistry parameters for Sprague Dawley rats. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2021; 84:357-388. [PMID: 33380269 DOI: 10.1080/15287394.2020.1867680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
This dermal study tested the potential toxicity of grade 3 (G3) and 4 (G4) organophosphate-containing aircraft engine oils in both new (G3-N, G4-N) and used states (G3-U, G4-U) to alter esterase activities in blood, brain and liver tissues, clinical chemistry parameters, and electrophysiology of hippocampal neurons. A 300 µl volume of undiluted oil was applied in Hill Top Chamber Systems®, then attached to fur-free test sites on backs of male and female Sprague Dawley rats for 6 hr/day, 5 days/week for 21 days. Recovery rats received similar treatments and kept for 14 days post-exposure to screen for reversibility, persistence, or delayed occurrence of toxicity. In brain, both versions of G3 and G4 significantly decreased (32-41%) female acetylcholinesterase (AChE) activity while in males only G3-N and G4-N reduced (33%) AChE activity. Oils did not markedly affect AChE in liver, regardless of gender. In whole blood, G3-U decreased female AChE (29%) which persisted during recovery (32%). G4-N significantly lowered (29%) butyrylcholinesterase (BChE) in male plasma, but this effect was resolved during recovery. For clinical chemistry indices, only globulin levels in female plasma significantly increased following G3-N or G4-N exposure. Preliminary electrophysiology data suggested that effects of both versions of G3 and G4 on hippocampal function may be gender dependent. Aircraft maintenance workers may be at risk if precautions are not taken to minimize long-term aircraft oil exposure.
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Affiliation(s)
- Isaie Sibomana
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Wright-Patterson Air Force Base, OH, USA
- Air Force Research Laboratory, 711 Human Performance Wing, Wright-Patterson Air Force Base, OH, USA
| | - Joyce G Rohan
- Environmental Health Effects Laboratory, Naval Medical Research Unit Dayton (NAMRU-D), Wright-Patterson Air Force Base, OH, USA
| | - David R Mattie
- Air Force Research Laboratory, 711 Human Performance Wing, Wright-Patterson Air Force Base, OH, USA
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Zaoui M, Sellami B, Boufahja F, Faloda F, Nahdi S, Alrezaki A, Alwasel S, Harrath AH. Effects of ferroelectric oxides of barium strontium titanate (Ba 0.85Sr 0.15TiO 3) nanoparticles on Ruditapes decussatus assessed through chemical, physiological, and biochemical methods. CHEMOSPHERE 2021; 265:129078. [PMID: 33272670 DOI: 10.1016/j.chemosphere.2020.129078] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Revised: 11/18/2020] [Accepted: 11/19/2020] [Indexed: 06/12/2023]
Abstract
Here, the effects of a newly designed ferroelectric oxide synthesized by solid reaction, barium strontium titanate [BST (85/15)] (Ba0.85Sr0.15TiO3), on the carpet shell clam Ruditapes decussatus were investigated. These clams were exposed to four concentrations of BST (85/15) nanoparticles (0.001, 0.01, 0.1, and 1 mg.L-1), and BST (85/15) was absorbed by R. decussatus in an exposure intensity-dependent manner. Measurements of clearance rate and biomarkers confirmed that the nanoparticles significantly affected the health of clams in an organ-dependent manner. Interestingly, BST (85/15) nanoparticles stimulated acetylcholinesterase (AChE) activity in the clams, suggesting their usefulness as antagonists of AChE inhibiting pollutants. These findings demonstrate the suitability of R. decussatus as a test organism to provide a framework for understanding the toxicological effects of these newly designed ferroelectrics. Moreover, concentrations of BST (85/15) < 0.1 mg.L-1 could be good alternatives to lead-based ferroelectric oxides and could be sustainable tools for use in electronic applications.
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Affiliation(s)
- M Zaoui
- University of Carthage, Faculty of Sciences of Bizerte, Laboratory of Environment Biomonitoring, Coastal Ecology and Ecotoxicology Unit, 7021, Zarzouna, Tunisia
| | - B Sellami
- University of Carthage, Faculty of Sciences of Bizerte, Laboratory of Environment Biomonitoring, Coastal Ecology and Ecotoxicology Unit, 7021, Zarzouna, Tunisia
| | - F Boufahja
- University of Carthage, Faculty of Sciences of Bizerte, Laboratory of Environment Biomonitoring, Coastal Ecology and Ecotoxicology Unit, 7021, Zarzouna, Tunisia
| | - F Faloda
- King Saud University, Zoology Department, College of Science, Box 2455, Riyadh, 11451, Saudi Arabia
| | - S Nahdi
- King Saud University, Zoology Department, College of Science, Box 2455, Riyadh, 11451, Saudi Arabia
| | - A Alrezaki
- King Saud University, Zoology Department, College of Science, Box 2455, Riyadh, 11451, Saudi Arabia
| | - S Alwasel
- King Saud University, Zoology Department, College of Science, Box 2455, Riyadh, 11451, Saudi Arabia
| | - A H Harrath
- King Saud University, Zoology Department, College of Science, Box 2455, Riyadh, 11451, Saudi Arabia.
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Kellis DM, Kaigler KF, Witherspoon E, Fadel JR, Wilson MA. Cholinergic neurotransmission in the basolateral amygdala during cued fear extinction. Neurobiol Stress 2020; 13:100279. [PMID: 33344731 PMCID: PMC7739185 DOI: 10.1016/j.ynstr.2020.100279] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 11/20/2020] [Accepted: 11/20/2020] [Indexed: 01/06/2023] Open
Abstract
Cholinergic neuromodulation plays an important role in numerous cognitive functions including regulating arousal and attention, as well as associative learning and extinction processes. Further, studies demonstrate that cholinergic inputs from the basal forebrain cholinergic system influence physiological responses in the basolateral amygdala (BLA) as well as fear extinction processes. Since rodent models display individual differences in conditioned fear and extinction responses, this study investigated if cholinergic transmission in the BLA during fear extinction could contribute to differences between extinction resistant and extinction competent phenotypes in outbred Long-Evans male rats. Experiment 1 used in vivo microdialysis to test the hypothesis that acetylcholine (ACH) efflux in the BLA would increase with presentation of an auditory conditioned stimulus (CS+) during extinction learning. Acetylcholine efflux was compared in rats exposed to the CS+, a CS- (the tone never paired with a footshock), or to a context shift alone (without CS+ tone presentation). Consistent with acetylcholine's role in attention and arousal, ACH efflux in the BLA was increased in all three groups (CS+, CS-, Shift Alone) by the initial context shift into the extinction learning chamber, but returned more rapidly to baseline levels in the Shift Alone group (no CS+). In contrast, in the group exposed to the CS+, ACH efflux in the BLA remained elevated during continued presentation of conditioned cues and returned to baseline more slowly, leading to an overall increase in ACH efflux compared with the Shift Alone group. Based on the very dense staining in the BLA for acetylcholinesterase (ACHE), Experiment 2 examined if individual differences in fear extinction were associated with differences in cholinesterase enzyme activity (CHE) in the BLA and/or plasma with a separate cohort of animals. Cholinesterase activity (post-testing) in both the BLA and plasma was higher in extinction competent rats versus rats resistant to extinction learning. There was also a significant negative correlation between BLA CHE activity and freezing during extinction learning. Taken together, our results support a role for ACH efflux in the BLA during cued fear extinction that may be modulated by individual differences in ACHE activity, and are associated with behavioral responses during fear extinction. These findings implicate individual differences in cholinergic regulation in the susceptibility to disorders with dysregulation of extinction learning, such post-traumatic stress disorder (PTSD) in humans. Basolateral amygdala acetylcholine efflux is increased during extinction learning. Acetylcholine efflux also increased transiently in amygdala during a context shift. Acetylcholinesterase activity in amygdala differed between extinction phenotypes. Amygdala cholinergic regulation contributes to variations in extinction learning.
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Affiliation(s)
- Devin M. Kellis
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, 29208, United States
| | - Kris Ford Kaigler
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, 29208, United States
| | - Eric Witherspoon
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, 29208, United States
| | - Jim R. Fadel
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, 29208, United States
| | - Marlene A. Wilson
- Columbia VA Health Care System, Columbia, SC, 29209, United States
- Corresponding author. Dept. Pharmacology, Physiology, & Neuroscience, Bldg 1 D26, University of South Carolina School of Medicine, Columbia, SC, 29208.
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Moutinho MF, de Almeida EA, Espíndola ELG, Daam MA, Schiesari L. Herbicides employed in sugarcane plantations have lethal and sublethal effects to larval Boana pardalis (Amphibia, Hylidae). ECOTOXICOLOGY (LONDON, ENGLAND) 2020; 29:1043-1051. [PMID: 32405782 DOI: 10.1007/s10646-020-02226-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 04/27/2020] [Indexed: 06/11/2023]
Abstract
The increasing demand for biofuels favored the expansion of sugarcane and, as a consequence, in the consumption of pesticides in Brazil. Amphibians are subject to pesticide exposure for occurring in or around sugarcane fields, and for breeding at the onset of the rainy season when pesticide consumption is common. We tested the hypothesis that herbicides used in sugarcane crops, although employed for weed control and manipulated at doses recommended by the manufacturers, can cause lethal and sublethal effects on amphibian larvae. Boana pardalis was exposed to glyphosate, ametryn, 2,4-D, metribuzin and acetochlor which account to up to 2/3 of the volume of herbicides employed in sugarcane production. High mortality was observed following prolonged exposure to ametryn (76%), acetochlor (68%) and glyphosate (15%); ametryn in addition significantly reduced activity rates and slowed developmental and growth rates. AChE activity was surprisingly stimulated by glyphosate, ametryn and 2,4-D, and GST activity by ametryn and acetochlor. Some of these sublethal effects, including the decrease in activity, growth and developmental rates, may have important consequences for individual performance for extending the larval period, and hence the risk of dessication, in the temporary and semi-permanent ponds where the species develops. Future studies should seek additional realism towards a risk analysis of the environmental contamination by herbicides through experiments manipulating not only active ingredients but also commercial formulations, as well as interactions among contaminants and other environmental stressors across the entire life cycle of native amphibian species.
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Affiliation(s)
- Mariana F Moutinho
- Programa de Pós-Graduação em Ecologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - Eduardo A de Almeida
- Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista, São José do Rio Preto, Brazil
- Fundação Universidade Regional de Blumenau, Blumenau, Brazil
| | - Evaldo L G Espíndola
- Centro de Recursos Hídricos e Ecologia Aplicada, Escola de Engenharia de São Carlos, Universidade de São Paulo, São Paulo, Brazil
| | - Michiel A Daam
- Departamento de Ciências Ambientais e Engenharia, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Lisboa, Portugal
| | - Luis Schiesari
- Escola de Artes, Ciências e Humanidades, Universidade de São Paulo, Avenida Arlindo Béttio 1000, São Paulo, 03828-000, Brazil.
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Del Pino J, Zeballos G, Anadon MJ, Díaz MJ, Moyano P, Díaz GG, García J, Lobo M, Frejo MT. Muscarinic M1 receptor partially modulates higher sensitivity to cadmium-induced cell death in primary basal forebrain cholinergic neurons: A cholinesterase variants dependent mechanism. Toxicology 2016; 361-362:1-11. [PMID: 27377441 DOI: 10.1016/j.tox.2016.06.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 06/23/2016] [Accepted: 06/30/2016] [Indexed: 11/26/2022]
Abstract
Cadmium is a toxic compound reported to produce cognitive dysfunctions, though the mechanisms involved are unknown. In a previous work we described how cadmium blocks cholinergic transmission and induces greater cell death in primary cholinergic neurons from the basal forebrain. It also induces cell death in SN56 cholinergic neurons from the basal forebrain through M1R blockage, alterations in the expression of AChE variants and GSK-3β, and an increase in Aβ and total and phosphorylated Tau protein levels. It was observed that the silencing or blockage of M1R altered ChAT activity, GSK-3β, AChE splice variants gene expression, and Aβ and Tau protein formation. Furthermore, AChE-S variants were associated with the same actions modulated by M1R. Accordingly, we hypothesized that cholinergic transmission blockage and higher sensitivity to cadmium-induced cell death of primary basal forebrain cholinergic neurons is mediated by M1R blockage, which triggers this effect through alteration of the expression of AChE variants. To prove this hypothesis, we evaluated, in primary culture from the basal forebrain region, whether M1R silencing induces greater cell death in cholinergic neurons than cadmium does, and whether in SN56 cells M1R mediates the mechanisms described so as to play a part in the cadmium induction of cholinergic transmission blockage and cell death in this cell line through alteration of the expression of AChE variants. Our results prove that M1R silencing by cadmium partially mediates the greater cell death observed on basal forebrain cholinergic neurons. Moreover, all previously described mechanisms for blocking cholinergic transmission and inducing cell death on SN56 cells after cadmium exposure are partially mediated by M1R through the alteration of AChE expression. Thus, our results may explain cognitive dysfunctions observed in cadmium toxicity.
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Affiliation(s)
- Javier Del Pino
- Department of Toxicology and Pharmacology, Veterinary School, Complutense University of Madrid, 28040 Madrid, Spain.
| | - Gabriela Zeballos
- Department of Toxicology and Legal Medicine, Medical School, Complutense University of Madrid, 28041 Madrid, Spain
| | - María José Anadon
- Department of Toxicology and Legal Medicine, Medical School, Complutense University of Madrid, 28041 Madrid, Spain
| | - María Jesús Díaz
- Department of Toxicology and Pharmacology, Veterinary School, Complutense University of Madrid, 28040 Madrid, Spain
| | - Paula Moyano
- Department of Toxicology and Legal Medicine, Medical School, Complutense University of Madrid, 28041 Madrid, Spain
| | - Gloria Gómez Díaz
- Department of Toxicology and Legal Medicine, Medical School, Complutense University of Madrid, 28041 Madrid, Spain
| | - Jimena García
- Department of Pharmacology, Health Sciences School, Alfonso X University, 28691 Madrid, Spain
| | - Margarita Lobo
- Department of Toxicology and Pharmacology, Veterinary School, Complutense University of Madrid, 28040 Madrid, Spain
| | - María Teresa Frejo
- Department of Toxicology and Pharmacology, Veterinary School, Complutense University of Madrid, 28040 Madrid, Spain
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SN56 basal forebrain cholinergic neuronal loss after acute and long-term chlorpyrifos exposure through oxidative stress generation; P75NTR and α7-nAChRs alterations mediated partially by AChE variants disruption. Toxicology 2016; 353-354:48-57. [DOI: 10.1016/j.tox.2016.05.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 05/02/2016] [Accepted: 05/03/2016] [Indexed: 12/12/2022]
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7
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Cadmium-induced cell death of basal forebrain cholinergic neurons mediated by muscarinic M1 receptor blockade, increase in GSK-3β enzyme, β-amyloid and tau protein levels. Arch Toxicol 2015; 90:1081-92. [DOI: 10.1007/s00204-015-1540-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Accepted: 05/05/2015] [Indexed: 01/02/2023]
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Zimmermann M. Neuronal AChE splice variants and their non-hydrolytic functions: redefining a target of AChE inhibitors? Br J Pharmacol 2014; 170:953-67. [PMID: 23991627 DOI: 10.1111/bph.12359] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 08/04/2013] [Accepted: 08/12/2013] [Indexed: 12/11/2022] Open
Abstract
AChE enzymatic inhibition is a core focus of pharmacological intervention in Alzheimer's disease (AD). Yet, AChE has also been ascribed non-hydrolytic functions, which seem related to its appearance in various isoforms. Neuronal AChE presents as a tailed form (AChE-T) predominantly found on the neuronal synapse, and a facultatively expressed readthough form (AChE-R), which exerts short to medium-term protective effects. Notably, this latter form is also found in the periphery. While these non-hydrolytic functions of AChE are most controversially discussed, there is evidence for them being additional targets of AChE inhibitors. This review aims to provide clarification as to the role of these AChE splice variants and their interplay with other cholinergic parameters and their being targets of AChE inhibition: AChE-R is particularly involved in the mediation of (anti-)apoptotic events in cholinergic cells, involving adaptation of various cholinergic parameters and a time-dependent link to the expression of neuroprotective factors. The AChE-T C-terminus is central to AChE activity regulation, while isolated AChE-T C-terminal fragments mediate toxic effects via the α7 nicotinic acetylcholine receptor. There is direct evidence for roles of AChE-T and AChE-R in neurodegeneration and neuroprotection, with these roles involving AChE as a key modulator of the cholinergic system: in vivo data further encourages the use of AChE inhibitors in the treatment of neurodegenerative conditions such as AD since effects on both enzymatic activity and the enzyme's non-hydrolytic functions can be postulated. It also suggests that novel AChE inhibitors should enhance protective AChE-R, while avoiding the concomitant up-regulation of AChE-T.
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Affiliation(s)
- M Zimmermann
- Department of Pharmacology, School of Pharmacy, Goethe University Frankfurt, Frankfurt am Main, Germany
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Acetylcholinesterase as a biomarker in environmental and occupational medicine: new insights and future perspectives. BIOMED RESEARCH INTERNATIONAL 2013; 2013:321213. [PMID: 23936791 PMCID: PMC3727120 DOI: 10.1155/2013/321213] [Citation(s) in RCA: 205] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2013] [Accepted: 06/20/2013] [Indexed: 01/23/2023]
Abstract
Acetylcholinesterase (AChE) is a key enzyme in the nervous system. It terminates nerve impulses by catalysing the hydrolysis of neurotransmitter acetylcholine. As a specific molecular target of organophosphate and carbamate pesticides, acetylcholinesterase activity and its inhibition has been early recognized to be a human biological marker of pesticide poisoning. Measurement of AChE inhibition has been increasingly used in the last two decades as a biomarker of effect on nervous system following exposure to organophosphate and carbamate pesticides in occupational and environmental medicine. The success of this biomarker arises from the fact that it meets a number of characteristics necessary for the successful application of a biological response as biomarker in human biomonitoring: the response is easy to measure, it shows a dose-dependent behavior to pollutant exposure, it is sensitive, and it exhibits a link to health adverse effects. The aim of this work is to review and discuss the recent findings about acetylcholinesterase, including its sensitivity to other pollutants and the expression of different splice variants. These insights open new perspective for the future use of this biomarker in environmental and occupational human health monitoring.
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Lin T, Duek O, Dori A, Kofman O. Differential long term effects of early diisopropylfluorophosphate exposure in Balb/C and C57Bl/J6 mice. Int J Dev Neurosci 2011; 30:113-20. [PMID: 22197972 DOI: 10.1016/j.ijdevneu.2011.12.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 12/01/2011] [Accepted: 12/08/2011] [Indexed: 11/17/2022] Open
Abstract
The long-term effect of postnatal administration of a sub-toxic dose of the irreversible acetylcholinesterase inhibitor diisopropylfluorophosphate (DFP) on depression and anxiety behavior was compared in two strains of inbred mice. C57BL/6J and Balb/C mice were injected for 7 consecutive days with either 1 mg/kg DFP or saline on postnatal days 14-20. Mice were tested at age 3-4 months for initial and learned anxiety using double-exposure elevated plus maze and to a novel enclosed environment. Depression was assayed using the sweet preference model of anhedonia and the forced swim test for despair. Postnatal DFP pretreatment led to less activity and more immobility in the elevated plus maze in both mouse strains in the first session. The effect was attenuated in the second session in the C57BL/6J strain but not the Balb/C strain. DFP did not affect the sweet preference or forced swim tests, suggesting a dissociation between the long-term effects of DFP on immobility in the context of approach-avoidance conflict (elevated plus maze) versus despair (forced swim).
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Affiliation(s)
- Tamar Lin
- Department of Psychology and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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Dori A, Oriel S, Livneh U, Duek O, Lin T, Kofman O. Acetylcholinesterase inhibitor pretreatment alters stress-induced expression of acetylcholinesterase transcripts in the mouse brain. Neuroscience 2011; 183:90-8. [DOI: 10.1016/j.neuroscience.2011.03.044] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Revised: 03/13/2011] [Accepted: 03/21/2011] [Indexed: 10/18/2022]
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Evron T, Greenberg D, Mor TS, Soreq H. Adaptive changes in acetylcholinesterase gene expression as mediators of recovery from chemical and biological insults. Toxicology 2007; 233:97-107. [PMID: 17005312 DOI: 10.1016/j.tox.2006.08.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2006] [Revised: 08/10/2006] [Accepted: 08/11/2006] [Indexed: 01/25/2023]
Abstract
Both organophosphate (OP) exposure and bacterial infection notably induce short- and long-term cholinergic responses. These span the central and peripheral nervous system, neuromuscular pathway and hematopoietic cells and involve over-expression of the "readthrough" variant of acetylcholinesterase, AChE-R, and its naturally cleavable C-terminal peptide ARP. However, the causal involvement of these changes with post-exposure recovery as opposed to apoptotic events remained to be demonstrated. Here, we report the establishment of stably transfected cell lines expressing catalytically active human "synaptic" AChE-S or AChE-R which are fully viable and non-apoptotic. In addition, intraperitoneally injected synthetic mouse ARP (mARP) elevated serum AChE levels post-paraoxon exposure. Moreover, mARP treatment ameliorated post-exposure increases in corticosterone and decreases in AChE gene expression and facilitated earlier retrieval of motor activity following both paraoxon and lipopolysaccharide (LPS) exposures. Our findings suggest a potential physiological role for overproduction of AChE-R and the ARP peptide following exposure to both chemical warfare agents and bacterial LPS.
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Affiliation(s)
- Tama Evron
- Department of Biological Chemistry, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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Brain regional acetylcholinesterase activity and muscarinic acetylcholine receptors in rats after repeated administration of cholinesterase inhibitors and its withdrawal. Toxicol Appl Pharmacol 2007; 219:151-61. [DOI: 10.1016/j.taap.2006.11.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Revised: 11/04/2006] [Accepted: 11/06/2006] [Indexed: 11/18/2022]
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Jameson RR, Seidler FJ, Slotkin TA. Nonenzymatic functions of acetylcholinesterase splice variants in the developmental neurotoxicity of organophosphates: chlorpyrifos, chlorpyrifos oxon, and diazinon. ENVIRONMENTAL HEALTH PERSPECTIVES 2007; 115:65-70. [PMID: 17366821 PMCID: PMC1797835 DOI: 10.1289/ehp.9487] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
BACKGROUND Organophosphate pesticides affect mammalian brain development through mechanisms separable from the inhibition of acetylcholinesterase (AChE) enzymatic activity and resultant cholinergic hyperstimulation. In the brain, AChE has two catalytically similar splice variants with distinct functions in development and repair. The rare, read-through isoform, AChE-R, is preferentially induced by injury and appears to promote repair and protect against neurodegeneration. Overexpression of the more abundant, synaptic isoform, AChE-S, enhances neurotoxicity. OBJECTIVES We exposed differentiating PC12 cells, a model for developing neurons, to 30 microM chlorpyrifos (CPF) or diazinon (DZN), or CPF oxon, the active metabolite that irreversibly inhibits AChE enzymatic activity, in order to determine whether they differentially induce the formation of AChE-S as a mechanistic predictor of developmental neurotoxicity. We then administered CPF or DZN to neonatal rats on postnatal days 1-4 using daily doses spanning the threshold for AChE inhibition (0-20%); we then evaluated AChE gene expression in forebrain and brainstem on post-natal day 5. RESULTS In PC12 cells, after 48 hr of exposure, CPF, CPF oxon, and DZN enhanced gene expression for AChE-R by about 20%, whereas CPF and DZN, but not CPF oxon, increased AChE-S expression by 20-40%. Thus, despite the fact that CPF oxon is a much more potent AChE inhibitor, it is the native compound (CPF) that induces expression of the neurotoxic AChE-S isoform. For in vivo exposures, 1 mg/kg CPF had little or no effect, but 0.5 or 2 mg/kg DZN induced both AChE-R and AChE-S, with a greater effect in males. CONCLUSIONS Our results indicate that nonenzymatic functions of AChE variants may participate in and be predictive of the relative developmental neurotoxicity of organophosphates, and that the various organophosphates differ in the degree to which they activate this mechanism.
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Affiliation(s)
| | | | - Theodore A. Slotkin
- Address correspondence to T.A. Slotkin, Box 3813 DUMC, Duke University Medical Center, Durham, NC 27710 USA. Telephone: (919) 681-8015. Fax: (919) 684-8197. E-mail:
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