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Tinant G, Van Larebeke M, Lemaire B, Courteille M, Gardin C, Neefs I, Das K, Page MM, Rees JF, Larondelle Y, Debier C. Dietary methylmercury and fatty acids affect the lipid metabolism of adipose tissue and liver in rainbow trout. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2023; 263:106673. [PMID: 37669601 DOI: 10.1016/j.aquatox.2023.106673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 08/24/2023] [Accepted: 08/25/2023] [Indexed: 09/07/2023]
Abstract
Methylmercury (MeHg) is a pervasive environmental contaminant in aquatic ecosystems that can reach elevated concentrations in fish of high trophic levels, such as salmonids. The present study aims at investigating the individual and combined impacts of dietary MeHg and fatty acids on lipid metabolism in juvenile rainbow trout (Oncorhynchus mykiss) with a focus on two key organs, adipose tissue and liver. MeHg and fatty acids are both known to act on energy homeostasis although little is known about their interplay on lipid metabolism in fish. Fish were fed diets enriched in linoleic acid (LA, 18:2 n-6), α-linolenic acid (ALA, 18:3 n-3), eicosapentaenoic acid (EPA, 20:5 n-3) or docosahexaenoic acid (DHA, 22:6 n-3) for ten weeks, with the addition of MeHg to the diets during the last six weeks (0, 2.4 or 5.5 mg MeHg/kg dry matter). LA and ALA are polyunsaturated fatty acids (PUFA) typical of plant-derived oils whereas EPA and DHA are n-3 long chain PUFA largely found in fish oil, all used in feed formulation in aquaculture. The results showed that the LA-enriched diet induced a higher whole-body lipid content compared to the three other diets. On the contrary, the addition of MeHg led to a significant reduction of the whole-body lipid content, regardless of the diet. Interestingly, the adipocytes were larger both in presence of LA, compared to EPA and DHA, or MeHg, indicating a lipogenic effect of these two compounds. No effect was, however, observed on lipid accumulation per gram of adipose tissue. The fatty acid composition of adipose tissue and liver was significantly modified by the dietary lipids, reflecting both the fatty acid composition of the diets and the high bioconversion capacity of the rainbow trout. Exposure to MeHg selectively led to a release of n-6 PUFA from the hepatic membranes of fish fed the LA-enriched diet, showing a disruption of the pathways using n-6 PUFA. This study highlights the significant impact of MeHg exposure and dietary fatty acids on lipid metabolism in fish. Further investigation is needed to elucidate the underlying mechanisms and to explore the potential involvement of other organs.
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Affiliation(s)
- Gilles Tinant
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix du Sud 4-5/L7.07.03, 1348 Louvain-la-Neuve, Belgium.
| | - Mélusine Van Larebeke
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix du Sud 4-5/L7.07.03, 1348 Louvain-la-Neuve, Belgium
| | - Benjamin Lemaire
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix du Sud 4-5/L7.07.03, 1348 Louvain-la-Neuve, Belgium
| | - Marine Courteille
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix du Sud 4-5/L7.07.03, 1348 Louvain-la-Neuve, Belgium
| | - Cécile Gardin
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix du Sud 4-5/L7.07.03, 1348 Louvain-la-Neuve, Belgium
| | - Ineke Neefs
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix du Sud 4-5/L7.07.03, 1348 Louvain-la-Neuve, Belgium
| | - Krishna Das
- Laboratory of Oceanology, Université de Liège, 11 Allée du 6 Août, B6C, 4000 Liège, Belgium
| | - Melissa M Page
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix du Sud 4-5/L7.07.03, 1348 Louvain-la-Neuve, Belgium
| | - Jean-François Rees
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix du Sud 4-5/L7.07.03, 1348 Louvain-la-Neuve, Belgium
| | - Yvan Larondelle
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix du Sud 4-5/L7.07.03, 1348 Louvain-la-Neuve, Belgium
| | - Cathy Debier
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix du Sud 4-5/L7.07.03, 1348 Louvain-la-Neuve, Belgium.
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Revisiting Astrocytic Roles in Methylmercury Intoxication. Mol Neurobiol 2021; 58:4293-4308. [PMID: 33990914 DOI: 10.1007/s12035-021-02420-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 05/04/2021] [Indexed: 02/06/2023]
Abstract
Intoxication by heavy metals such as methylmercury (MeHg) is recognized as a global health problem, with strong implications in central nervous system pathologies. Most of these neuropathological conditions involve vascular, neurotransmitter recycling, and oxidative balance disruption leading to accelerated decline in fine balance, and learning, memory, and visual processes as main outcomes. Besides neurons, astrocytes are involved in virtually all the brain processes and perform important roles in neurological response following injuries. Due to astrocytes' strategic functions in brain homeostasis, these cells became the subject of several studies on MeHg intoxication. The most heterogenous glial cells, astrocytes, are composed of plenty of receptors and transporters to dialogue with neurons and other cells and to monitor extracellular environment responding tightly through fluctuation of cytosolic ions. The overall toxicity of MeHg might be determined on the basis of the balance between MeHg-mediated injury to neurons and protective responses from astrocytes. Although the role of neurons in MeHg intoxication is relatively well-established, the role of the astrocytes is only beginning to be understood. In this review, we update the information on astroglial modulation of the MeHg-induced neurotoxicity, providing remarks on their protective and deleterious roles and insights for future studies.
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Novo JP, Martins B, Raposo RS, Pereira FC, Oriá RB, Malva JO, Fontes-Ribeiro C. Cellular and Molecular Mechanisms Mediating Methylmercury Neurotoxicity and Neuroinflammation. Int J Mol Sci 2021; 22:ijms22063101. [PMID: 33803585 PMCID: PMC8003103 DOI: 10.3390/ijms22063101] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 03/06/2021] [Accepted: 03/15/2021] [Indexed: 02/06/2023] Open
Abstract
Methylmercury (MeHg) toxicity is a major environmental concern. In the aquatic reservoir, MeHg bioaccumulates along the food chain until it is consumed by riverine populations. There has been much interest in the neurotoxicity of MeHg due to recent environmental disasters. Studies have also addressed the implications of long-term MeHg exposure for humans. The central nervous system is particularly susceptible to the deleterious effects of MeHg, as evidenced by clinical symptoms and histopathological changes in poisoned humans. In vitro and in vivo studies have been crucial in deciphering the molecular mechanisms underlying MeHg-induced neurotoxicity. A collection of cellular and molecular alterations including cytokine release, oxidative stress, mitochondrial dysfunction, Ca2+ and glutamate dyshomeostasis, and cell death mechanisms are important consequences of brain cells exposure to MeHg. The purpose of this review is to organize an overview of the mercury cycle and MeHg poisoning events and to summarize data from cellular, animal, and human studies focusing on MeHg effects in neurons and glial cells. This review proposes an up-to-date compendium that will serve as a starting point for further studies and a consultation reference of published studies.
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Affiliation(s)
- João P. Novo
- Institute for Clinical and Biomedical Research (iCBR), Center for Innovative Biomedicine and Biotechnology (CIBB), and Institute of Pharmacology and Experimental Therapeutics, Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; (J.P.N.); (B.M.); (R.S.R.); (F.C.P.)
| | - Beatriz Martins
- Institute for Clinical and Biomedical Research (iCBR), Center for Innovative Biomedicine and Biotechnology (CIBB), and Institute of Pharmacology and Experimental Therapeutics, Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; (J.P.N.); (B.M.); (R.S.R.); (F.C.P.)
| | - Ramon S. Raposo
- Institute for Clinical and Biomedical Research (iCBR), Center for Innovative Biomedicine and Biotechnology (CIBB), and Institute of Pharmacology and Experimental Therapeutics, Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; (J.P.N.); (B.M.); (R.S.R.); (F.C.P.)
- Experimental Biology Core, University of Fortaleza, Health Sciences, Fortaleza 60110-001, Brazil
| | - Frederico C. Pereira
- Institute for Clinical and Biomedical Research (iCBR), Center for Innovative Biomedicine and Biotechnology (CIBB), and Institute of Pharmacology and Experimental Therapeutics, Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; (J.P.N.); (B.M.); (R.S.R.); (F.C.P.)
| | - Reinaldo B. Oriá
- Laboratory of Tissue Healing, Ontogeny and Nutrition, Department of Morphology and Institute of Biomedicine, School of Medicine, Federal University of Ceará, Fortaleza 60430-270, Brazil;
| | - João O. Malva
- Institute for Clinical and Biomedical Research (iCBR), Center for Innovative Biomedicine and Biotechnology (CIBB), and Institute of Pharmacology and Experimental Therapeutics, Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; (J.P.N.); (B.M.); (R.S.R.); (F.C.P.)
- Correspondence: (J.O.M.); (C.F.-R.)
| | - Carlos Fontes-Ribeiro
- Institute for Clinical and Biomedical Research (iCBR), Center for Innovative Biomedicine and Biotechnology (CIBB), and Institute of Pharmacology and Experimental Therapeutics, Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; (J.P.N.); (B.M.); (R.S.R.); (F.C.P.)
- Correspondence: (J.O.M.); (C.F.-R.)
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Tinant G, Neefs I, Das K, Rees JF, Larondelle Y, Debier C. Methylmercury displays pro-adipogenic properties in rainbow trout preadipocytes. CHEMOSPHERE 2021; 263:127917. [PMID: 33297014 DOI: 10.1016/j.chemosphere.2020.127917] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 07/27/2020] [Accepted: 08/03/2020] [Indexed: 06/12/2023]
Abstract
Methylmercury (MeHg) is a ubiquitous contaminant largely found in aquatic environments, especially in species at high trophic level such as salmonids. The aim of this study was to evaluate the effects of MeHg on adipocyte differentiation and lipid metabolism in rainbow trout. Primary cultured preadipocytes were exposed to increasing concentrations of MeHg during six days with or without a hormonal cocktail. Main results showed a dose-dependent intracellular accumulation of neutral lipids with a preferential uptake of n-3 polyunsaturated fatty acids. Interestingly, this accumulation occurred after a fairly low uptake of MeHg by preadipocytes and was maintained after the cellular exposure to MeHg. In membrane phospholipids, arachidonic acid (20:4 n-6) was released in a dose-dependent manner. At the transcriptional level, the expression of several adipocyte-specific genes (perilipin 2 and apolipoprotein Eb) as well as lipid-related genes (fatty acid synthase and fatty acid binding protein 11a) was up-regulated in preadipocytes exposed to MeHg. These results highlight for the first time the disrupting effect of MeHg in trout adipocyte metabolism, providing new insights regarding the role of environmental pollutants in adipose tissue dysfunction and related pathologies.
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Affiliation(s)
- Gilles Tinant
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix Du Sud 4-5/L7.07.03, 1348, Louvain-la-Neuve, Belgium.
| | - Ineke Neefs
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix Du Sud 4-5/L7.07.03, 1348, Louvain-la-Neuve, Belgium
| | - Krishna Das
- Laboratory of Oceanology, Université de Liège, 11 Allée Du 6 Août, B6C, 4000, Liège, Belgium
| | - Jean-François Rees
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix Du Sud 4-5/L7.07.03, 1348, Louvain-la-Neuve, Belgium
| | - Yvan Larondelle
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix Du Sud 4-5/L7.07.03, 1348, Louvain-la-Neuve, Belgium
| | - Cathy Debier
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix Du Sud 4-5/L7.07.03, 1348, Louvain-la-Neuve, Belgium.
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Modified expression of antioxidant genes in lobster cockroach, Nauphoeta cinerea exposed to methylmercury and monosodium glutamate. Chem Biol Interact 2020; 318:108969. [DOI: 10.1016/j.cbi.2020.108969] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 01/19/2020] [Accepted: 01/27/2020] [Indexed: 12/21/2022]
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6
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Sun XY, Liu T, Sun J, Wang XJ. Synthesis and application of coumarin fluorescence probes. RSC Adv 2020; 10:10826-10847. [PMID: 35492912 PMCID: PMC9050418 DOI: 10.1039/c9ra10290f] [Citation(s) in RCA: 97] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 02/15/2020] [Indexed: 12/11/2022] Open
Abstract
In recent years, the research on fluorescent probes has developed rapidly. Coumarin fluorescent probes have also been one of the hot topics in recent years. For the synthesis and application of coumarin fluorescent probes, great progress has been made. Coumarin fluorescent probes have become more and more widely used in biochemistry, environmental protection, and disease prevention, and have broad prospects. This review introduces the three main light emitting mechanisms (PET, ICT, FRET) of fluorescent probes, and enumerates some probes based on this light emitting mechanism. In terms of the synthesis of coumarin fluorescent probes, the existing substituents on the core of coumarin compounds were modified. Based on the positions of the modified substituents, some of the fluorescent probes reported in the past ten years are listed. Most of the fluorescent probes are formed by modifying the 3 and 7 position substituents on the mother nucleus, and the 4 and 8 position substituents are relatively less modified. In terms of probe applications, the detection and application of coumarin fluorescent probes for Cu2+, Hg2+, Mg2+, Zn2+, pH, environmental polarity, and active oxygen and sulfide in the past ten years are mainly introduced. In recent years, the research on fluorescent probes has developed rapidly.![]()
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Affiliation(s)
- Xiao-ya Sun
- School of Medicine and Life Sciences
- University of Jinan
- Shandong Academy of Medical Sciences
- Jinan 250200
- China
| | - Teng Liu
- Institute of Materia Medical
- Shandong First Medical University & Shandong Academy of Medical Sciences
- Jinan 250062
- China
- Key Laboratory for Biotech-Drugs Ministry of Health
| | - Jie Sun
- Institute of Materia Medical
- Shandong First Medical University & Shandong Academy of Medical Sciences
- Jinan 250062
- China
- Key Laboratory for Biotech-Drugs Ministry of Health
| | - Xiao-jing Wang
- Institute of Materia Medical
- Shandong First Medical University & Shandong Academy of Medical Sciences
- Jinan 250062
- China
- Key Laboratory for Biotech-Drugs Ministry of Health
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Shinozaki Y, Danjo Y, Koizumi S. Microglial ROCK is essential for chronic methylmercury‐induced neurodegeneration. J Neurochem 2019; 151:64-78. [DOI: 10.1111/jnc.14817] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 06/20/2019] [Accepted: 06/25/2019] [Indexed: 02/07/2023]
Affiliation(s)
- Youichi Shinozaki
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine University of Yamanashi Chuo Yamanashi Japan
| | - Yosuke Danjo
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine University of Yamanashi Chuo Yamanashi Japan
| | - Schuichi Koizumi
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine University of Yamanashi Chuo Yamanashi Japan
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Prince LM, Aschner M, Bowman AB. Human-induced pluripotent stems cells as a model to dissect the selective neurotoxicity of methylmercury. Biochim Biophys Acta Gen Subj 2019; 1863:129300. [PMID: 30742955 DOI: 10.1016/j.bbagen.2019.02.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 01/09/2019] [Accepted: 02/01/2019] [Indexed: 01/07/2023]
Abstract
Methylmercury (MeHg) is a potent neurotoxicant affecting both the developing and mature central nervous system (CNS) with apparent indiscriminate disruption of multiple homeostatic pathways. However, genetic and environmental modifiers contribute significant variability to neurotoxicity associated with human exposures. MeHg displays developmental stage and neural lineage selective neurotoxicity. To identify mechanistic-based neuroprotective strategies to mitigate human MeHg exposure risk, it will be critical to improve our understanding of the basis of MeHg neurotoxicity and of this selective neurotoxicity. Here, we propose that human-based pluripotent stem cell cellular approaches may enable mechanistic insight into genetic pathways that modify sensitivity of specific neural lineages to MeHg-induced neurotoxicity. Such studies are crucial for the development of novel disease modifying strategies impinging on MeHg exposure vulnerability.
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Affiliation(s)
- Lisa M Prince
- School of Health Sciences, Purdue University, West Lafayette, IN 47907-2051, United States
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, United States
| | - Aaron B Bowman
- School of Health Sciences, Purdue University, West Lafayette, IN 47907-2051, United States.
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Giri D, Bankura A, Patra SK. Poly(benzodithieno-imidazole-alt-carbazole) based π-conjugated copolymers: Highly selective and sensitive turn-off fluorescent probes for Hg2+. POLYMER 2018. [DOI: 10.1016/j.polymer.2018.10.069] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Ferain A, Bonnineau C, Neefs I, Das K, Larondelle Y, Rees JF, Debier C, Lemaire B. Transcriptional effects of phospholipid fatty acid profile on rainbow trout liver cells exposed to methylmercury. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2018; 199:174-187. [PMID: 29649756 DOI: 10.1016/j.aquatox.2018.03.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 03/16/2018] [Accepted: 03/20/2018] [Indexed: 06/08/2023]
Abstract
Lipids, and their constitutive fatty acids, are key nutrients for fish health as they provide energy, maintain cell structure, are precursors of signalling molecules and act as nuclear receptor ligands. These specific roles may be of crucial importance in a context of exposure to pollutants. We recently showed that the fatty acid profile of rainbow trout liver cell phospholipids modulates sensitivity to an acute methylmercury challenge. In order to investigate mechanisms of effects, we herein tested whether specific polyunsaturated fatty acids (PUFAs) may protect cells from methylmercury through decreasing intracellular mercury accumulation and/or enhancing cellular defences (e.g. via modulation of gene expression patterns). We also investigated the inverse relationship and assessed the impact of methylmercury on cellular fatty acid metabolism. To do so, the fatty acid composition of rainbow trout liver cell phospholipids was first modified by incubating them in a medium enriched in a specific PUFA from either the n-3 family (alpha-linolenic acid, ALA; eicosapentaenoic acid, EPA) or the n-6 family (linoleic acid, LA; arachidonic acid, AA). Cells were then exposed to methylmercury (0.15 or 0.50 μM) for 24 h and sampled thereafter for assessing phospholipid fatty acid profile, intracellular total mercury burden, and expression pattern of genes involved in fatty acid metabolism, synthesis of PUFA-derived signalling molecules and stress response. We observed that cells incorporated the given PUFA and some biotransformation products in their phospholipids. Methylmercury had few impacts on this cellular phospholipid composition. None of the PUFA enrichments affected the cellular mercury burden, suggesting that the previously observed cytoprotection conferred by ALA and EPA was not linked to a global decrease in cellular accumulation of mercury. Fatty acid enrichments and methylmercury exposure both modulated gene expression patterns. Genes involved in the synthesis of PUFA-derived signalling molecules, in stress response and the orphan cytochrome P450 20A1 were identified as possible sites of interaction between fatty acids and methylmercury in rainbow trout liver cells.
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Affiliation(s)
- Aline Ferain
- Institute of Life Sciences, Université catholique de Louvain, Place Croix du Sud 2/L7.05.08, B-1348 Louvain-la-Neuve, Belgium.
| | - Chloé Bonnineau
- Institute of Life Sciences, Université catholique de Louvain, Place Croix du Sud 2/L7.05.08, B-1348 Louvain-la-Neuve, Belgium; Irstea, UR RiverLy, Centre de Lyon-Villeurbanne, 5, 69625 Villeurbanne, France
| | - Ineke Neefs
- Institute of Life Sciences, Université catholique de Louvain, Place Croix du Sud 2/L7.05.08, B-1348 Louvain-la-Neuve, Belgium
| | - Krishna Das
- Freshwater and Oceanic sciences Unit of reSearch (FOCUS), Laboratory of Oceanology, Université de Liège, Allée du 6 août B6C, B-4000 Liège, Belgium
| | - Yvan Larondelle
- Institute of Life Sciences, Université catholique de Louvain, Place Croix du Sud 2/L7.05.08, B-1348 Louvain-la-Neuve, Belgium
| | - Jean-François Rees
- Institute of Life Sciences, Université catholique de Louvain, Place Croix du Sud 2/L7.05.08, B-1348 Louvain-la-Neuve, Belgium
| | - Cathy Debier
- Institute of Life Sciences, Université catholique de Louvain, Place Croix du Sud 2/L7.05.08, B-1348 Louvain-la-Neuve, Belgium.
| | - Benjamin Lemaire
- Institute of Life Sciences, Université catholique de Louvain, Place Croix du Sud 2/L7.05.08, B-1348 Louvain-la-Neuve, Belgium
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Emandi G, Flanagan KJ, Senge MO. Fluorescent imidazole-based chemosensors for the reversible detection of cyanide and mercury ions. Photochem Photobiol Sci 2018; 17:1450-1461. [DOI: 10.1039/c8pp00226f] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Imidazole-based conjugate acts as a reversible sensor towards CN− and Hg2+ in CH3CN–H2O.
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Affiliation(s)
- Ganapathi Emandi
- SFI Tetrapyrrole Laboratory
- School of Chemistry
- Trinity Biomedical Sciences Institute
- 152-160 Pearse Street
- Trinity College Dublin
| | - Keith J. Flanagan
- SFI Tetrapyrrole Laboratory
- School of Chemistry
- Trinity Biomedical Sciences Institute
- 152-160 Pearse Street
- Trinity College Dublin
| | - Mathias O. Senge
- SFI Tetrapyrrole Laboratory
- School of Chemistry
- Trinity Biomedical Sciences Institute
- 152-160 Pearse Street
- Trinity College Dublin
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12
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Siregar AS, Prayogo NA. The disruptive effect of mercury chloride (HgCl) on gene expression of gonadotrophin hormones and testosterone level in male silver sharkminnow ( Osteochilus hasseltii C.V.) (Teleostei: Cyprinidae). THE EUROPEAN ZOOLOGICAL JOURNAL 2017. [DOI: 10.1080/24750263.2017.1352040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Affiliation(s)
- A. S. Siregar
- Fishery and Marine Faculty, Jenderal Soedirman University , Indonesia
| | - N. A. Prayogo
- Fishery and Marine Faculty, Jenderal Soedirman University , Indonesia
- Center of Maritime and Bioscience, Jenderal Soedirman University , Indonesia
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Culbreth M, Zhang Z, Aschner M. Methylmercury augments Nrf2 activity by downregulation of the Src family kinase Fyn. Neurotoxicology 2017; 62:200-206. [PMID: 28736149 DOI: 10.1016/j.neuro.2017.07.028] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 07/17/2017] [Accepted: 07/17/2017] [Indexed: 12/26/2022]
Abstract
Methylmercury (MeHg) is a potent developmental neurotoxicant that induces an oxidative stress response in the brain. It has been demonstrated that MeHg exposure increases nuclear factor erythroid 2-related factor 2 (Nrf2) activity. Nrf2 is a transcription factor that translocates to the nucleus in response to oxidative stress, and upregulates phase II detoxifying enzymes. Although, Nrf2 activity is augmented subsequent to MeHg exposure, it has yet to be established whether Nrf2 moves into the nucleus as a result. Furthermore, the potential effect MeHg might have on the non-receptor tyrosine kinase, Fyn, has not been addressed. Fyn phosphorylates Nrf2 in the nucleus, resulting in its inactivation, and consequent downregulation of the oxidative stress response. Here, we observe Nrf2 translocates to the nucleus subsequent to MeHg-induced oxidative stress. This response is concomitant with reduced Fyn expression and nuclear localization. Moreover, we detected an increase in phosphorylated Akt and glycogen synthase kinase 3 beta (GSK-3β) at activating and inhibitory sites, respectively. Akt phosphorylates and inhibits GSK-3β, which subsequently prevents Fyn phosphorylation to signal nuclear import. Our results demonstrate MeHg downregulates Fyn to maintain Nrf2 activity, and further illuminate a potential mechanism by which MeHg elicits neurotoxicity.
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Affiliation(s)
- Megan Culbreth
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, United States.
| | - Ziyan Zhang
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, United States
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Risher JF, Tucker P. Alkyl Mercury-Induced Toxicity: Multiple Mechanisms of Action. REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2017; 240:105-149. [PMID: 27161558 PMCID: PMC10508330 DOI: 10.1007/398_2016_1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
There are a number of mechanisms by which alkylmercury compounds cause toxic action in the body. Collectively, published studies reveal that there are some similarities between the mechanisms of the toxic action of the mono-alkyl mercury compounds methylmercury (MeHg) and ethylmercury (EtHg). This paper represents a summary of some of the studies regarding these mechanisms of action in order to facilitate the understanding of the many varied effects of alkylmercurials in the human body. The similarities in mechanisms of toxicity for MeHg and EtHg are presented and compared. The difference in manifested toxicity of MeHg and EtHg are likely the result of the differences in exposure, metabolism, and elimination from the body, rather than differences in mechanisms of action between the two.
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Affiliation(s)
- John F Risher
- Division of Toxicology and Human Health Sciences, Agency for Toxic Substances and Disease Registry, 1600 Clifton Road (MS F-58), Atlanta, GA, 30333, USA.
| | - Pamela Tucker
- Division of Toxicology and Human Health Sciences, Agency for Toxic Substances and Disease Registry, 1600 Clifton Road (MS F-58), Atlanta, GA, 30333, USA
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Blossom SJ, Melnyk SB, Li M, Wessinger WD, Cooney CA. Inflammatory and oxidative stress-related effects associated with neurotoxicity are maintained after exclusively prenatal trichloroethylene exposure. Neurotoxicology 2016; 59:164-174. [PMID: 26812193 DOI: 10.1016/j.neuro.2016.01.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 01/04/2016] [Accepted: 01/05/2016] [Indexed: 10/22/2022]
Abstract
Trichloroethylene (TCE) is a widespread environmental toxicant with immunotoxic and neurotoxic potential. Previous studies have shown that continuous developmental exposure to TCE encompassing gestation and early life as well as postnatal only exposure in the drinking water of MRL+/+ mice promoted CD4+ T cell immunotoxicity, glutathione depletion and oxidative stress in the cerebellum, as well increased locomotor activity in male offspring. The purpose of this study was to characterize the effects of exclusively prenatal exposure on these parameters. Another goal was to investigate potential plasma oxidative stress/inflammatory biomarkers to possibly be used as predictors of TCE-mediated neurotoxicity. In the current study, 6 week old male offspring of dams exposed gestationally to 0, 0.01, and 0.1mg/ml TCE in the drinking water were evaluated. Our results confirmed that the oxidized phenotype in plasma and cerebellum was maintained after exclusively prenatal exposure. A Phenotypic analysis by flow cytometry revealed that TCE exposure expanded the effector/memory subset of peripheral CD4+ T cells in association with increased production of pro-inflammatory cytokines IFN-γ and IL-17. Serum biomarkers of oxidative stress and inflammation were also elevated in plasma suggesting that systemic effects are important and may be used to predict neurotoxicity in our model. These results suggested that the prenatal period is a critical stage of life by which the developing CNS and immune system are susceptible to long-lasting changes mediated by TCE.
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Affiliation(s)
- Sarah J Blossom
- Department of Pediatrics, University of Arkansas for Medical Sciences, College of Medicine, Arkansas Children's Hospital Research Institute, 13 Children's Way, Little Rock, AR 72202, USA.
| | - Stepan B Melnyk
- Department of Pediatrics, University of Arkansas for Medical Sciences, College of Medicine, Arkansas Children's Hospital Research Institute, 13 Children's Way, Little Rock, AR 72202, USA
| | - Ming Li
- Department of Pediatrics, University of Arkansas for Medical Sciences, College of Medicine, Arkansas Children's Hospital Research Institute, 13 Children's Way, Little Rock, AR 72202, USA
| | - William D Wessinger
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, College of Medicine, 4301 West Markham St., Little Rock, AR 72205, USA
| | - Craig A Cooney
- Department of Research and Development, Central Arkansas Veterans Healthcare System, Little Rock, AR 72205, USA
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Dysregulation of Glutamate Cycling Mediates Methylmercury-Induced Neurotoxicity. ADVANCES IN NEUROBIOLOGY 2016; 13:295-305. [PMID: 27885634 DOI: 10.1007/978-3-319-45096-4_11] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
To examine the toxicological implications of glutamate, this chapter will focus specifically on its impact in the brain. More explicitly, it will illustrate the role glutamate plays in mediating methylmercury (MeHg)-induced neurotoxicity. In this chapter, one intends to highlight the processes that occur prior to glutamate-stimulated excitotoxicity and subsequent neurodegeneration. As such, it will emphasize three main routes by which MeHg alters glutamate homeostasis. It is essential to recognize that these effects are not mutually exclusive, and that they synergistically influence glutamate dysregulation. Furthermore, the consequences of MeHg exposure will be presented here as a direct pathway; however, it must be noted these effects occur simultaneously. First, glutamate uptake will be reviewed emphasizing the function of astrocytes. Next, the induction of oxidative stress by MeHg exposure will be discussed. This process has a two-fold effect on glutamate homeostasis by (1) inhibiting extracellular glutamate uptake and (2) altering transcription of genes vital to glutamate cycling. Finally, the impact glutamate dysregulation has on glutathione synthesis will be examined. Although this chapter centers on the link between glutamate and MeHg toxicity, it is imperative that the reader acknowledges the processes discussed here can be extended to any pro-oxidant.
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Methylmercury Increases and Eicosapentaenoic Acid Decreases the Relative Amounts of Arachidonic Acid-Containing Phospholipids in Mouse Brain. Lipids 2015; 51:61-73. [DOI: 10.1007/s11745-015-4087-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 10/02/2015] [Indexed: 12/29/2022]
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Kumar A, Kim HS. N-(3-Imidazolyl)propyl dansylamide as a selective Hg(2+) sensor in aqueous media through electron transfer. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015; 148:250-254. [PMID: 25897719 DOI: 10.1016/j.saa.2015.03.091] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 02/26/2015] [Accepted: 03/21/2015] [Indexed: 06/04/2023]
Abstract
N-Imidazolylpropyl dansylamide 1 was synthesized for the sensing of metal ions and found to be selective and sensitive toward Hg(2+) ions in a PBS-EtOH (1:4, pH=7.4) solution. The sensing ability of probe 1 was examined by UV-Vis, fluorescence, and (1)H NMR spectroscopy. The sensing of Hg(2+) exhibited a quenching of emission band at λmax=515 nm of probe 1, which was associated with quenching of green fluorescence emission under 365 nm illumination. Probe 1 showed a good association constant with Hg(2+) (Ka=6.48×10(4) M(-1)) with a stoichiometry of 1:1 in PBS-EtOH (1:4, pH=7.4) having the lowest detection limit of 1 μM for Hg(2+); on the other hand, probe 2, which has no imidazole moiety, was not able to detect any metal ion. In the case of probe 1, electrons on the imidazole nitrogen are available for electron transfer (ET), which was responsible for its green emission band that was quenched on addition of Hg(2+); this clearly indicates that these electrons were used for the formation of a coordinate bond with Hg(2+) and that ET was switched off.
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Affiliation(s)
- Ashwani Kumar
- Department of Applied Chemistry, School of Applied Chemical Engineering, Kyungpook National University, Daegu 702-701, Republic of Korea
| | - Hong-Seok Kim
- Department of Applied Chemistry, School of Applied Chemical Engineering, Kyungpook National University, Daegu 702-701, Republic of Korea.
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Balamurugan A, Lee HI. Aldoxime-Derived Water-Soluble Polymer for the Multiple Analyte Sensing: Consecutive and Selective Detection of Hg2+, Ag+, ClO–, and Cysteine in Aqueous Media. Macromolecules 2015. [DOI: 10.1021/acs.macromol.5b00731] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- A. Balamurugan
- Department of Chemistry, University of Ulsan, Ulsan 680-749, Republic of Korea
| | - Hyung-il Lee
- Department of Chemistry, University of Ulsan, Ulsan 680-749, Republic of Korea
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Balamurugan A, Lee HI. Water-Soluble Polymeric Probes for the Selective Sensing of Mercury Ion: pH-Driven Controllable Detection Sensitivity and Time. Macromolecules 2015. [DOI: 10.1021/ma502350p] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- A. Balamurugan
- Department of Chemistry, University of Ulsan, Ulsan 680-749, Republic of Korea
| | - Hyung-il Lee
- Department of Chemistry, University of Ulsan, Ulsan 680-749, Republic of Korea
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Pal A, Bag B. Dual mode signaling responses of a rhodamine based probe and its immobilization onto a silica gel surface for specific mercury ion detection. Dalton Trans 2015; 44:15304-15. [DOI: 10.1039/c5dt01334h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The amino-ethyl-rhodamine-B based probe 2 appended with a 3-aminomethyl-(2-amino-1-pyridyl) group retained its Hg(ii)-specific chromogenic and fluorogenic signaling responses in an aqueous medium even upon immobilization onto a silica gel surface for selective detection and extraction of Hg(ii) ions.
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Affiliation(s)
- Ajoy Pal
- Colloids and Materials Chemistry Department
- Academy of Scientific and Innovative Research
- CSIR-Institute of Minerals and Materials Technology
- Bhubaneswar-751 013
- India
| | - Bamaprasad Bag
- Colloids and Materials Chemistry Department
- Academy of Scientific and Innovative Research
- CSIR-Institute of Minerals and Materials Technology
- Bhubaneswar-751 013
- India
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Caito S, Zeng H, Aschner JL, Aschner M. Methylmercury alters the activities of Hsp90 client proteins, prostaglandin E synthase/p23 (PGES/23) and nNOS. PLoS One 2014; 9:e98161. [PMID: 24852575 PMCID: PMC4031136 DOI: 10.1371/journal.pone.0098161] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 04/29/2014] [Indexed: 01/14/2023] Open
Abstract
Methylmercury (MeHg) is a persistent pollutant with known neurotoxic effects. We have previously shown that astrocytes accumulate MeHg and play a prominent role in mediating MeHg toxicity in the central nervous system (CNS) by altering glutamate signaling, generating oxidative stress, depleting glutathione (GSH) and initiating lipid peroxidation. Interestingly, all of these pathways can be regulated by the constitutively expressed, 90-kDa heat shock protein, Hsp90. As Hsp90 function is regulated by oxidative stress, we hypothesized that MeHg disrupts Hsp90-client protein functions. Astrocytes were treated with MeHg and expression of Hsp90, as well as the abundance of complexes of Hsp90-neuronal nitric oxide synthase (nNOS) and Hsp90-prostaglandin E synthase/p23 (PGES/p23) were assessed. MeHg exposure decreased Hsp90 protein expression following 12 h of treatment while shorter exposures had no effect on Hsp90 protein expression. Interestingly, following 1 or 6 h of MeHg exposure, Hsp90 binding to PGES/p23 or nNOS was significantly increased, resulting in increased prostaglandin E2 (PGE2) synthesis from MeHg-treated astrocytes. These effects were attenuated by the Hsp90 antagonist, geldanmycin. NOS activity was increased following MeHg treatment while cGMP formation was decreased. This was accompanied by an increase in •O2− and H2O2 levels, suggesting that MeHg uncouples NO formation from NO-dependent signaling and increases oxidative stress. Altogether, our data demonstrates that Hsp90 interactions with client proteins are increased following MeHg exposure, but over time Hsp90 levels decline, contributing to oxidative stress and MeHg-dependent excitotoxicity.
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Affiliation(s)
- Samuel Caito
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Heng Zeng
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Judy L Aschner
- Department of Pediatrics and Obstetrics & Gynecology and Women's Health, Albert Einstein College of Medicine of Yeshiva University and Children's Hospital at Montefiore, Bronx, New York, United States of America
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, United States of America; Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America; Department of Pediatrics and Obstetrics & Gynecology and Women's Health, Albert Einstein College of Medicine of Yeshiva University and Children's Hospital at Montefiore, Bronx, New York, United States of America; The Kennedy Center, Albert Einstein College of Medicine, Bronx, New York, United States of America
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Areti S, Yarramala DS, Samanta K, Hinge VK, Khedkar J, Rao CP. Glyco-conjugate as selective switch-on molecule for Hg2+in the presence of albumin proteins, blood serum milieu and on silica gel solid support. RSC Adv 2014. [DOI: 10.1039/c4ra00223g] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Biswal B, Bag B. Switching selectivity between Pb2+ and Hg2+ ions through variation of substituents at xanthene end; ‘turn-on’ signalling responses by FRET modulation. RSC Adv 2014. [DOI: 10.1039/c4ra04152f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Substitution at amino groups attached to the xanthene core modulates the stereo-electronic situation to switch selectivity; a FRET mediated signalling with a distinctive coupling of fluorophores.
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Affiliation(s)
- Biswonath Biswal
- Colloids and Materials Chemistry Department
- Academy of Scientific and Innovative Research
- CSIR-Institute of Minerals and Materials Technology
- Bhubaneswar-751 013, India
| | - Bamaprasad Bag
- Colloids and Materials Chemistry Department
- Academy of Scientific and Innovative Research
- CSIR-Institute of Minerals and Materials Technology
- Bhubaneswar-751 013, India
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Biswal B, Bag B. Preferences of rhodamine coupled (aminoalkyl)-piperazine probes towards Hg(II) ion and their FRET mediated signaling. Org Biomol Chem 2013; 11:4975-92. [PMID: 23783407 DOI: 10.1039/c3ob40648b] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The metal ion induced absorption and emission signaling pattern of rhodamine coupled bis-(aminopropyl)-piperazine (1-3) and (aminoethyl)-piperazine (4) based probes evaluated in MeCN as well as in an MeCN-H2O binary mixture medium revealed that these probes exhibit optical signaling perturbations to a varying extent in MeCN, however, their complexation induced signaling could be tuned selectively towards Hg(II) in the presence of an aqueous component in the solvent medium where competitive interactions such as metal-probe interactions and hydration of metal ions play the determining factor to induce aqueous promoted Hg(II) selectivity. Attachment of another fluorophore (anthracene and nitrobenzofurazan moieties in 2 and 3 respectively) at the other end of the rhodamine coupled bis-(aminopropyl)-piperazine receptor enabled these probes to facilitate a complexation induced fluorescence resonance energy transfer (FRET) from the excited fluorophore to the ring-opened rhodamine along with contributions through operative PET inhibition and rhodamine delactonization processes. The enhancement in absorption transition of these probes at ~557 nm upon selective Hg(II)-complexation and consequent colourless to pink colour change in the solution imply a chromogenic signaling pattern whereas simultaneous fluorescence amplification and/or FRET initiation lead to fluorogenic signaling to facilitate detection at lower concentration. The Hg(II)-selective photo-physical spectral modulation in the presence of other competitive metal ions, and their reversible dual channel signaling pattern under the action of counter anions or chelating agents such as EDTA or ethylenediamine establish the potential of these probes for highly selective, sensitive and reversible 'OFF-ON-OFF' detection of Hg(II). The complexation induced optical signaling pattern of probes with a propyl-linker in their receptor (1-3) in comparison with that of 4 consisting of an ethyl-spacer indicate that signaling probe design with a substituted 'aminoalkyl-lactonized-rhodamine' subunit preferentially exhibit Hg(II) selective and sensitive dual mode signaling in an organic-aqueous mixture medium irrespective of carbon-length of the flexible alkyl spacer.
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Affiliation(s)
- Biswonath Biswal
- Colloids and Materials Chemistry Department, CSIR-Institute of Minerals and Materials Technology, P.O.: R.R.L., Bhubaneswar-751 013, Odisha, India
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Mazerik JN, Mikkilineni H, Kuppusamy VA, Steinhour E, Peltz A, Marsh CB, Kuppusamy P, Parinandi NL. Mercury activates phospholipase a(2) and induces formation of arachidonic Acid metabolites in vascular endothelial cells. Toxicol Mech Methods 2012; 17:541-57. [PMID: 20020881 DOI: 10.1080/15376510701380505] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
ABSTRACT Currently, mercury has been identified as a risk factor in cardiovascular diseases among humans. Here, we tested our hypothesis that mercury modulates the activity of the vascular endothelial cell (EC) lipid signaling enzyme phospholipase A(2) (PLA(2)), which is an important player in the EC barrier functions. Monolayers of bovine pulmonary artery ECs (BPAECs) in culture, following labeling of membrane phospholipids with [(3)H]arachidonic acid (AA), were exposed to the inorganic form of mercury, mercury chloride, and the release of free AA (index of PLA(2) activity) and formation of AA metabolites were determined by liquid scintillation counting and enzyme immunoassay, respectively. Mercury chloride significantly activated PLA(2) in BPAECs in a dose-dependent (0 to 50 muM) and time-dependent (0 to 120 min) fashion. Metal chelators significantly attenuated mercury-induced PLA(2) activation, suggesting that cellular mercury-ligand interaction is required for the enzyme activation and that chelators are suitable blockers for mercury-induced PLA(2) activation in ECs. Sulfhydryl (thiol-protective) agents, calcium chelating agents, and cPLA(2)-specific inhibitor also significantly attenuated the mercury-induced PLA(2), suggesting the role of thiol and calcium in the activation of cPLA(2) in BPAECs. Significant formation of AA metabolites, including the release of total prostaglandins, thromboxane B(2), and 8-isoprostane, were observed in BPAECs following their exposure to mercury chloride. Mercury chloride induced cytotoxicity as observed by the altered cell morphology and enhanced trypan blue uptake, which was attenuated by the cPLA(2) inhibitor AACOCF(3). The results of this study revealed that inorganic mercury-induced PLA(2) activation through the thiol and calcium signaling and the formation of bioactive AA metabolites further demonstrated the association of PLA(2) with the cytotoxicity of mercury in ECs. Overall, the results of the current study underscore the importance of PLA(2) signaling in mercury-induced endothelial dysfunctions.
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Affiliation(s)
- Jessica N Mazerik
- Lipid Signaling and Lipidomics Laboratory, Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, OH, United States
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Unfolding with mercury: anthracene-oxyquinoline dyad as a fluorescent indicator for Hg(II). Tetrahedron Lett 2012. [DOI: 10.1016/j.tetlet.2012.03.053] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Amlund H, Andreasen L, Torstensen BE. Dietary methylmercury and vegetable oil affects brain lipid composition in Atlantic salmon (Salmo salar L.). Food Chem Toxicol 2012; 50:518-25. [DOI: 10.1016/j.fct.2011.12.041] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Revised: 12/12/2011] [Accepted: 12/22/2011] [Indexed: 11/17/2022]
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Ni M, Li X, Rocha JBT, Farina M, Aschner M. Glia and methylmercury neurotoxicity. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2012; 75:1091-1101. [PMID: 22852858 PMCID: PMC4059390 DOI: 10.1080/15287394.2012.697840] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Methylmercury (MeHg) is a global environmental pollutant with significant adverse effects on human health. As the major target of MeHg, the central nervous system (CNS) exhibits the most recognizable poisoning symptoms. The role of the two major nonneuronal cell types, astrocytes and microglia, in response to MeHg exposure was recently compared. These two cell types share several common features in MeHg toxicity, but interestingly, these cells types also exhibit distinct response kinetics, indicating a cell-specific role in mediating MeHg-induced neurotoxicity. The aim of this study was to review the most recent literature and summarize key features of glial responses to this organometal.
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Affiliation(s)
- Mingwei Ni
- Department of Surgery, New York Hospital Medical Center Queens, New York City, New York, USA
| | - Xin Li
- Neuroscience Graduate Program, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - João B. T. Rocha
- Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Marcelo Farina
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Michael Aschner
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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Wormser U, Brodsky B, Milatovic D, Finkelstein Y, Farina M, Rocha JB, Aschner M. Protective effect of a novel peptide against methylmercury-induced toxicity in rat primary astrocytes. Neurotoxicology 2011; 33:763-8. [PMID: 22186600 DOI: 10.1016/j.neuro.2011.12.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Revised: 12/02/2011] [Accepted: 12/06/2011] [Indexed: 10/14/2022]
Abstract
Methylmercury (MeHg) is an environmental neurotoxicant associated with aberrant central nervous system (CNS) functions. In this study, we examined the protective effect of a novel anti-inflammatory and cytoprotective nonapeptide, termed IIIM1, against MeHg-induced toxicity in cultured rat neonatal primary astrocytes. Astrocytes were pretreated for 66 h with 5 μg/ml IIIM1 (4.95 μM) followed by 6 h exposure to MeHg (5 μM). MeHg significantly increased F(2)-isoprostane generation, a lipid peroxidation biomarker of oxidative injury and this effect was significantly reduced upon pre-treatment with IIIM1. The MeHg-induced increase in levels of prostaglandin E(2) (PGE(2)), biomarkers of inflammatory responses, was also decreased in the peptide-treated cells. Mass spectrometry analysis revealed no chemical or binding interaction between MeHg and IIIM1, indicating that intracellular cytoprotective mechanism of action accounts for the neuroprotection rather than direct intracellular neutralization of the neurotoxicant with the peptide. These findings point to therapeutic potential for IIIM1 in a plethora of conditions associated with reactive oxygen species (ROS) generation. The implication of these findings may prove beneficial in designing new treatment modalities that efficiently suppress neurotoxicity, triggered not only by MeHg, but also by other metals and environmental agents, as well as chronic disease conditions that inherently increase reactive radical production and inflammatory signaling.
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Affiliation(s)
- Uri Wormser
- Institute of Drug Research, School of Pharmacy, the Hebrew University, 91120 Jerusalem, Israel
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Gharaei A, Ghaffari M, Keyvanshokooh S, Akrami R. Changes in metabolic enzymes, cortisol and glucose concentrations of Beluga (Huso huso) exposed to dietary methylmercury. FISH PHYSIOLOGY AND BIOCHEMISTRY 2011; 37:485-93. [PMID: 21110088 DOI: 10.1007/s10695-010-9450-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Accepted: 11/09/2010] [Indexed: 05/18/2023]
Abstract
In this paper, effects of dietary methylmercury (MeHg) on several blood biochemical parameters including GLU (glucose), LDH (lactate dehydrogenase), AST (aspartate aminotransferase), ALT (alanine aminotransferase), ALP (alkaline phosphatase) and cortisol were investigated in the Beluga sturgeon (Huso huso). Beluga juveniles were fed for 32 days on four diets containing MeHg (control: 0.04 mg kg⁻¹; low: 0.76 mg kg⁻¹; medium: 7.88 mg kg⁻¹; and high 16.22 mg kg⁻¹ treatment). Significant increases (P < 0.05) were observed in all biochemical parameters, except ALP levels, which decreased significantly (P < 0.05) compared to the control group with either dose- or time-dependent effects. These results suggest that long-term dietary MeHg exposure may affect metabolic enzyme activity and glucose levels in Belugas. These findings provide useful information for environmental and fishery officials to apply in future decisions for managing fish resources in Caspian Sea.
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Affiliation(s)
- Ahmad Gharaei
- Department of fisheries, International Hamoun Wetland Research Institute, University of Zabol, P. O. Box: 98615-538, Zabol, Sistan & Balouchestan, Iran.
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Maximino C, Araujo J, Leão LKR, Grisolia ABA, Oliveira KRM, Lima MG, Batista EDJO, Crespo-López ME, Gouveia A, Herculano AM. Possible role of serotoninergic system in the neurobehavioral impairment induced by acute methylmercury exposure in zebrafish (Danio rerio). Neurotoxicol Teratol 2011; 33:727-34. [PMID: 21871955 DOI: 10.1016/j.ntt.2011.08.006] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Revised: 08/08/2011] [Accepted: 08/09/2011] [Indexed: 01/31/2023]
Abstract
Adult zebrafish were treated acutely with methylmercury (1.0 or 5.0 μg g(-1), i.p.) and, 24h after treatment, were tested in two behavioral models of anxiety, the novel tank and the light/dark preference tests. At the smaller dose, methylmercury produced a marked anxiogenic profile in both tests, while the greater dose produced hyperlocomotion in the novel tank test. These effects were accompanied by a decrease in extracellular levels of serotonin, and an increase in extracellular levels of tryptamine-4,5-dione, a partially oxidized metabolite of serotonin. A marked increase in the formation of malondialdehyde, a marker of oxidative stress, accompanied these parameters. It is suggested that methylmercury-induced oxidative stress produced mitochondrial dysfunction and originated tryptamine-4,5-dione, which could have further inhibited tryptophan hydroxylase. These results underscore the importance of assessing acute, low-level neurobehavioral effects of methylmercury.
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Affiliation(s)
- Caio Maximino
- Laboratório de Neuroendocrinologia, Instituto de Ciências Biológicas, Universidade Federal do Pará, Brazil.
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Chang JY. Methylmercury-induced IL-6 release requires phospholipase C activities. Neurosci Lett 2011; 496:152-6. [PMID: 21513770 DOI: 10.1016/j.neulet.2011.04.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 03/23/2011] [Accepted: 04/05/2011] [Indexed: 10/18/2022]
Abstract
Methylmercury (MeHg) is a neurotoxin capable of causing severe damage to the CNS, especially in the developing fetus. Glia in the CNS release a number of cytokines that are important for proper CNS development and function. We reported earlier that MeHg could induce interleukin-6 (IL-6) release in primary mouse glia. This finding is significant considering previous reports indicating that sustained IL-6 exposure could be detrimental to cerebellar granule neurons, one of the major cellular targets of MeHg cytotoxicity. By using pharmacological antagonists against phophatidycholine- and phosphoinositol-specific phospholipase C, the current study indicated that phospholipase C activity was necessary for MeHg-induced IL-6 release. Results from pharmacological antagonists further suggested that the calcium signaling initiated by phospholipase C appeared essential for this event. In contrast, protein kinase C activity did not appear to be important. Even though mitogen-activated protein kinases were important for IL-6 release in some experimental systems, these enzymes did not appear to be required for MeHg-induced IL-6 release in glia. Based on these data and those reported by us and others, there is a possibility that MeHg-induced phospholipase C activation initiates a calcium signaling that causes phospholipase A(2) activation. This, in turn, leads to arachidonic acid and lysophosphatidyl choline generation, both of which are potent inducers for IL-6 release.
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Affiliation(s)
- Jason Y Chang
- Department of Neurobiology and Developmental Sciences, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
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Bandela A, Chinta JP, Rao CP. Role of the conformational changes brought in the arms of the 1,3-di-capped conjugate of calix[4]arene (L) in turning on the fluorescence of L by Hg2+. Dalton Trans 2011; 40:11367-70. [DOI: 10.1039/c1dt11208b] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Zapata F, Caballero A, Molina P, Tarraga A. A ferrocene-quinoxaline derivative as a highly selective probe for colorimetric and redox sensing of toxic mercury(II) cations. SENSORS 2010; 10:11311-21. [PMID: 22163528 PMCID: PMC3231088 DOI: 10.3390/s101211311] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Revised: 11/15/2010] [Accepted: 11/26/2010] [Indexed: 12/15/2022]
Abstract
A new chemosensor molecule 3 based on a ferrocene-quinoxaline dyad recognizes mercury (II) cations in acetonitrile solution. Upon recognition, an anodic shift of the ferrocene/ferrocenium oxidation peaks and a progressive red-shift (Δλ = 140 nm) of the low-energy band, are observed in its absorption spectrum. This change in the absorption spectrum is accompanied by a colour change from orange to deep green, which can be used for a “naked-eye” detection of this metal cation.
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Affiliation(s)
| | | | - Pedro Molina
- Authors to whom correspondence should be addressed; E-Mail: (P.M.); Tel.: +34-868-887-496; E-Mail: (A.T.); Tel.: +34-868-887-499; Fax: +34-868-884-149
| | - Alberto Tarraga
- Authors to whom correspondence should be addressed; E-Mail: (P.M.); Tel.: +34-868-887-496; E-Mail: (A.T.); Tel.: +34-868-887-499; Fax: +34-868-884-149
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Gharaei A, Mahboudi F, Esmaili-Sari A, Edalat R, Adeli A, Keyvanshokooh S. Molecular cloning of cDNA of mammalian and chicken II gonadotropin-releasing hormones (mGnRHs and cGnRH-II) in the beluga (Huso huso) and the disruptive effect of methylmercury on gene expression. FISH PHYSIOLOGY AND BIOCHEMISTRY 2010; 36:803-817. [PMID: 19821139 DOI: 10.1007/s10695-009-9356-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2008] [Accepted: 09/16/2009] [Indexed: 05/28/2023]
Abstract
Two gonadotropin-releasing hormone (GnRH) isoforms were identified in the beluga (Huso huso) brain by cDNA sequencing: prepro-mammalian GnRH (mGnRH) and prepro-chicken GnRH-II (cGnRH-II). The nucleotide sequences of the beluga mGnRH and cGnRH-II precursors are 273 and 258 base pairs (bp) long, encoding peptides of 91 and 86 amino acids, respectively. To investigate the effect of methylmercury (MeHg) on GnRH gene expression, animals were fed with four diets containing increasing levels of MeHg (0 mg kg(-1) [control]; 0.76 mg kg(-1) [low]; 7.8 mg kg(-1) [medium]; 16.22 mg kg(-1) [high]) for 32 days. The effects of MeHg on brain GnRH mRNA levels were evaluated by real-time PCR. A significant decrease in brain mGnRH and cGnRH-II mRNA levels were detected in fish receiving high dietary MeHg dose compared to controls on day 11 (P < 0.05). On day 18 and 32, all treatment groups had significantly lower brain mGnRH and cGnRH-II mRNA levels compared to the control group (P < 0.05). These findings demonstrate a disruptive role of MeHg on the level of brain mGnRH and cGnRH-II mRNAs in immature beluga.
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Affiliation(s)
- Ahmad Gharaei
- Department of Fisheries, Faculty of Natural Resources, Universityof Zabol, P.O.Box 98615-538, Zabol, Sistan & Blouchestan, Iran.
| | | | - Abbas Esmaili-Sari
- Department of Environment, Faculty of Natural Resources and Marine Science, Tarbiat Modares University, Noor, Mazandaran, Iran
| | - Rozita Edalat
- Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Ahmad Adeli
- Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Saeed Keyvanshokooh
- Department of Fisheries, Faculty of Marine Natural Resources, Khorramshahr University of Marine Science and Technology, Khorramshahr, Khouzestan, Iran
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Ellis BC, Gattoni-Celli S, Kindy MS. The impact of methylmercury on 1,25-dihydroxyvitamin D3-induced transcriptomic responses in dolphin skin cells. Biol Chem 2010; 391:245-258. [DOI: 10.1515/bc.2010.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
AbstractThe Atlantic bottlenose dolphin has been the focus of much attention owing to the considerable impact of environmental stress on its health and the associated implications for human health. Here, we used skin cells from the dolphin to investigate the protective role of the vitamin D pathway against environmental stressors. We previously reported that dolphin skin cells respond to 1,25-dihydroxyvitamin D3 (1,25D3), the bioactive metabolite of vitamin D3, by upregulation of the vitamin D receptor (VDR) and expression of several genes. Methylmercury is a highly bioaccumulative environmental stressor of relevance to the dolphin. We currently report that in dolphin cells sublethal concentrations of methylmercury compromise the ability of 1,25D3 to upregulate VDR, to transactivate a vitamin D-sensitive promoter, and to express specific target genes. These results help elucidate the effects of vitamin D and methylmercury on innate immunity in dolphin skin and potentially in human skin as well, considering similarities in the vitamin D pathway between the two species.
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Affiliation(s)
- Blake C. Ellis
- Marine Biomedicine and Environmental Sciences Center, Medical University of South Carolina, 331 Fort Johnson Road, Charleston, SC 29412, USA
| | - Sebastiano Gattoni-Celli
- Marine Biomedicine and Environmental Sciences Center, Medical University of South Carolina, 331 Fort Johnson Road, Charleston, SC 29412, USA
| | - Mark S. Kindy
- Marine Biomedicine and Environmental Sciences Center, Medical University of South Carolina, 331 Fort Johnson Road, Charleston, SC 29412, USA
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Abdalla F, Bellé L, De Bona K, Bitencourt P, Pigatto A, Moretto M. Allium sativum L. extract prevents methyl mercury-induced cytotoxicity in peripheral blood leukocytes (LS). Food Chem Toxicol 2010; 48:417-21. [DOI: 10.1016/j.fct.2009.10.033] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Revised: 08/19/2009] [Accepted: 10/26/2009] [Indexed: 10/20/2022]
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Voutsadaki S, Tsikalas GK, Klontzas E, Froudakis GE, Katerinopoulos HE. A “turn-on” coumarin-based fluorescent sensor with high selectivity for mercury ions in aqueous media. Chem Commun (Camb) 2010; 46:3292-4. [DOI: 10.1039/b926384e] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Balamurugan A, Reddy MLP, Jayakannan M. Carboxylic-functionalized water soluble π-conjugated polymer: Highly selective and efficient chemosensor for mercury(II) ions. ACTA ACUST UNITED AC 2009. [DOI: 10.1002/pola.23566] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Chang JY, Tsai PF. IL-6 release from mouse glia caused by MeHg requires cytosolic phospholipase A2 activation. Neurosci Lett 2009; 461:85-9. [PMID: 19539721 DOI: 10.1016/j.neulet.2009.06.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2009] [Revised: 06/02/2009] [Accepted: 06/11/2009] [Indexed: 11/28/2022]
Abstract
Methylmercury is a potent neurotoxin that causes severe neurological disorders in fetuses and young children. Recent studies indicated that MeHg could alter levels of immune mediators produced by cells of the central nervous system. Results from this study indicated that MeHg could greatly induce IL-6 release from primary mouse glial cultures. This property was not shared by other cytotoxic heavy metals, such as CdCl(2) or HgCl(2). MeHg was known to induce cytosolic phospholipase A(2) (PLA(2)) activation and expression, and this enzyme was required for IL-6 induction in some experimental systems. Further experiments using structurally distinct pharmacological agents were performed to test the hypothesis that MeHg induced PLA(2) activation was necessary for MeHg induced IL-6 release. Results indicated that AACOCF(3) (>or=10 microM), MAFP (>or=0.625 microM) and BEL (>or=0.625 microM) significantly reduced MeHg induced IL-6 release in glia. However, these PLA(2) inhibitors did not block MeHg induced GSH depletion. These results suggested that PLA(2) activation was required for MeHg to induce glial IL-6 release.
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Affiliation(s)
- Jason Y Chang
- Department of Neurobiology and Developmental Sciences, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
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Yang YK, Ko SK, Shin I, Tae J. Fluorescent detection of methylmercury by desulfurization reaction of rhodamine hydrazide derivatives. Org Biomol Chem 2009; 7:4590-3. [DOI: 10.1039/b915723a] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Kaur P, Heggland I, Aschner M, Syversen T. Docosahexaenoic acid may act as a neuroprotector for methylmercury-induced neurotoxicity in primary neural cell cultures. Neurotoxicology 2008; 29:978-87. [DOI: 10.1016/j.neuro.2008.06.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Revised: 06/02/2008] [Accepted: 06/09/2008] [Indexed: 10/21/2022]
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Affiliation(s)
- Elizabeth M Nolan
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge Massachusetts 02139, USA
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Jin X, Chan HM, Lok E, Kapal K, Taylor M, Kubow S, Mehta R. Dietary fats modulate methylmercury-mediated systemic oxidative stress and oxidative DNA damage in rats. Food Chem Toxicol 2008; 46:1706-20. [DOI: 10.1016/j.fct.2008.01.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Revised: 12/11/2007] [Accepted: 01/08/2008] [Indexed: 01/08/2023]
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46
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Mazerik JN, Hagele T, Sherwani S, Ciapala V, Butler S, Kuppusamy ML, Hunter M, Kuppusamy P, Marsh CB, Parinandi NL. Phospholipase A2 activation regulates cytotoxicity of methylmercury in vascular endothelial cells. Int J Toxicol 2008; 26:553-69. [PMID: 18066971 DOI: 10.1080/10915810701707759] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Mercury has been identified as a risk factor for cardiovascular disease among humans. Through diet, mainly fish consumption, humans are exposed to methylmercury, the biomethylated organic form of environmental mercury. As the endothelium is an important player in homeostasis of the cardiovascular system, here, the authors tested their hypothesis that methylmercury activates the lipid signaling enzyme phospholipase A(2) (PLA(2)) in vascular endothelial cells (ECs), causing upstream regulation of cytotoxicity. To test this hypothesis, the authors used bovine pulmonary artery ECs (BPAECs) cultured in monolayers, following labeling of their membrane phospholipids with [(3)H]arachidonic acid (AA). The cells were exposed to methylmercury chloride (MMC) and then the release of free AA (index of PLA(2) activity) and lactate dehydrogenase (LDH; index of cytotoxicity) were determined by liquid scintillation counting and spectrophotometry, respectively. MMC significantly activated PLA(2) in a dose-dependent (5 to 15 microM) and time-dependent (0 to 60 min) fashion. Sulfhydryl (thiol-protective) agents, calcium chelators, antioxidants, and PLA(2)-specific inhibitors attenuated the MMC-induced PLA(2) activation, suggesting the role of thiols, reactive oxygen species (ROS), and calcium in the activation of PLA(2) in BPAECs. MMC also induced the loss of thiols and increase of lipid peroxidation in BPAECs. MMC induced cytotoxicity in BPAECs as observed by the altered cell morphology and LDH leak, which was significantly attenuated by PLA(2) inhibitors. This study established that PLA(2) activation through thiols, calcium, and oxidative stress was associated with the cytotoxicity of MMC in BPAECs, drawing attention to the involvement of PLA(2) signaling in the methylmercury-induced vascular endothelial dysfunctions.
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Affiliation(s)
- Jessica N Mazerik
- Lipid Signaling and Lipidomics Laboratory, Division of Pulmonary, Allergy, Critical Care, The Ohio State University College of Medicine, Columbus, Ohio, USA
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Metallothionein in the central nervous system: Roles in protection, regeneration and cognition. Neurotoxicology 2008; 29:489-503. [PMID: 18313142 DOI: 10.1016/j.neuro.2007.12.006] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Accepted: 12/22/2007] [Indexed: 12/23/2022]
Abstract
Metallothionein (MT) is an enigmatic protein, and its physiological role remains a matter of intense study and debate 50 years after its discovery. This is particularly true of its function in the central nervous system (CNS), where the challenge remains to link its known biochemical properties of metal binding and free radical scavenging to the intricate workings of brain. In this compilation of four reports, first delivered at the 11th International Neurotoxicology Association (INA-11) Meeting, June 2007, the authors present the work of their laboratories, each of which gives an important insight into the actions of MT in the brain. What emerges is that MT has the potential to contribute to a variety of processes, including neuroprotection, regeneration, and even cognitive functions. In this article, the properties and CNS expression of MT are briefly reviewed before Dr Hidalgo describes his pioneering work using transgenic models of MT expression to demonstrate how this protein plays a major role in the defence of the CNS against neurodegenerative disorders and other CNS injuries. His group's work leads to two further questions, what are the mechanisms at the cellular level by which MT acts, and does this protein influence higher order issues of architecture and cognition? These topics are addressed in the second and third sections of this review by Dr West, and Dr Levin and Dr Eddins, respectively. Finally, Dr Aschner examines the ability of MT to protect against a specific toxicant, methylmercury, in the CNS.
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Aschner J, Aschner M. Methylmercury Neurotoxicity: Exploring Potential Novel Targets. THE OPEN TOXICOLOGY JOURNAL 2007; 1:1-9. [PMID: 31178939 PMCID: PMC6555406 DOI: 10.2174/1874340400701010001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Mechanistic studies on the effects of MeHg in the central nervous system (CNS) have been limited to morphology, substrate uptake and macromolecular synthesis, differentiation, and changes in gene expression during development and adulthood, but its primary site of action has yet to be identified. Proper functioning of the nitric oxide synthase (NOS)-cyclic GMP and the cyclooxygenase (COX)-prostaglandin (PG) signaling pathways in the CNS depend on post-translational modifications of key enzymes by chaperone proteins. The ability of MeHg to alter or inhibit chaperone-client protein interactions is hitherto unexplored, and potentially offers an upstream unifying mechanism for the plethora of MeHg effects, ranging from reactive species generation (ROS) generation, mitochondrial dysfunction, changes in redox potential, macromolecule synthesis, and cell swelling. In view of the prominent function of astrocytes in the maintenance of the extracellular milieu and their critical role in mediating MeHg neurotoxicity, they afford a relevant and well-established experimental model. The present review is predicated on (a) the remarkable affinity of mercurials for the anionic form of sulfhydryl (-SH) groups, (b) the essential role of thiols in protein biochemistry, and (c) the role of molecular chaperone proteins, such as heat shock protein 90 (Hsp90) in the regulation of protein redox status by facilitating the formation and breakage of disulfide bridges. We offer potential sites where MeHg may interfere with cellular homeostasis and advance a novel mechanistic model for MeHg-induced neurotoxicity.
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Affiliation(s)
- J.L. Aschner
- Department of Pediatrics and the Kennedy Center for Research on Human Development
| | - M. Aschner
- Department of Pediatrics and the Kennedy Center for Research on Human Development
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
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Aschner M, Syversen T, Souza DO, Rocha JBT, Farina M. Involvement of glutamate and reactive oxygen species in methylmercury neurotoxicity. Braz J Med Biol Res 2007; 40:285-91. [PMID: 17334523 DOI: 10.1590/s0100-879x2007000300001] [Citation(s) in RCA: 206] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2006] [Accepted: 01/16/2007] [Indexed: 01/08/2023] Open
Abstract
This review addresses the mechanisms of methylmercury (MeHg)-induced neurotoxicity, specifically examining the role of oxidative stress in mediating neuronal damage. A number of critical findings point to a central role for astrocytes in mediating MeHg-induced neurotoxicity as evidenced by the following observations: a) MeHg preferentially accumulates in astrocytes; b) MeHg specifically inhibits glutamate uptake in astrocytes; c) neuronal dysfunction is secondary to disturbances in astrocytes. The generation of reactive oxygen species (ROS) by MeHg has been observed in various experimental paradigms. For example, MeHg enhances ROS formation both in vivo (rodent cerebellum) and in vitro (isolated rat brain synaptosomes), as well as in neuronal and mixed reaggregating cell cultures. Antioxidants, including selenocompounds, can rescue astrocytes from MeHg-induced cytotoxicity by reducing ROS formation. We emphasize that oxidative stress plays a significant role in mediating MeHg-induced neurotoxic damage with active involvement of the mitochondria in this process. Furthermore, we provide a mechanistic overview on oxidative stress induced by MeHg that is triggered by a series of molecular events such as activation of various kinases, stress proteins and other immediate early genes culminating in cell damage.
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Affiliation(s)
- M Aschner
- Departments of Pediatrics and Pharmacology, Vanderbilt University Medical Center, B3307 Medical Center North, Nashville, TN 37232, USA.
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Kang MS, Jeong JY, Seo JH, Jeon HJ, Jung KM, Chin MR, Moon CK, Bonventre JV, Jung SY, Kim DK. Methylmercury-induced toxicity is mediated by enhanced intracellular calcium through activation of phosphatidylcholine-specific phospholipase C. Toxicol Appl Pharmacol 2006; 216:206-15. [PMID: 16854443 DOI: 10.1016/j.taap.2006.04.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Revised: 04/09/2006] [Accepted: 04/28/2006] [Indexed: 11/16/2022]
Abstract
Methylmercury (MeHg) is a ubiquitous environmental toxicant to which humans can be exposed by ingestion of contaminated food. MeHg has been suggested to exert its toxicity through its high reactivity to thiols, generation of arachidonic acid and reactive oxygen species (ROS), and elevation of free intracellular Ca(2+) levels ([Ca(2+)](i)). However, the precise mechanism has not been fully defined. Here we show that phosphatidylcholine-specific phospholipase C (PC-PLC) is a critical pathway for MeHg-induced toxicity in MDCK cells. D609, an inhibitor of PC-PLC, significantly reversed the toxicity in a time- and dose-dependent manner with concomitant inhibition of the diacylglycerol (DAG) generation and the phosphatidylcholine (PC)-breakdown. MeHg activated the group IV cytosolic phospholipase A(2) (cPLA(2)) and acidic form of sphingomyelinase (A-SMase) downstream of PC-PLC, but these enzymes as well as protein kinase C (PKC) were not linked to the toxicity by MeHg. Furthermore, MeHg produced ROS, which did not affect the toxicity. Addition of EGTA to culture media resulted in partial decrease of [Ca(2+)](i) and partially blocked the toxicity. In contrast, when the cells were treated with MeHg in the presence of Ca(2+) in the culture media, D609 completely prevented cell death with parallel decrease in [Ca(2+)](i). Our results demonstrated that MeHg-induced toxicity was linked to elevation of [Ca(2+)](i) through activation of PC-PLC, but not attributable to the signaling pathways such as cPLA(2), A-SMase, and PKC, or to the generation of ROS.
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Affiliation(s)
- Mi Sun Kang
- Department of Environmental and Health Chemistry, College of Pharmacy, Chung-Ang University, Seoul, 221 Huksuk-Dong, Dongjak-Ku, Seoul 156-756, South Korea
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