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Kang B, Wang J, Guo S, Yang L. Mercury-induced toxicity: Mechanisms, molecular pathways, and gene regulation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 943:173577. [PMID: 38852866 DOI: 10.1016/j.scitotenv.2024.173577] [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: 11/30/2023] [Revised: 03/01/2024] [Accepted: 05/25/2024] [Indexed: 06/11/2024]
Abstract
Mercury is a well-known neurotoxicant for humans and wildlife. The epidemic of mercury poisoning in Japan has clearly demonstrated that chronic exposure to methylmercury (MeHg) results in serious neurological damage to the cerebral and cerebellar cortex, leading to the dysfunction of the central nervous system (CNS), especially in infants exposed to MeHg in utero. The occurrences of poisoning have caused a wide public concern regarding the health risk emanating from MeHg exposure; particularly those eating large amounts of fish may experience the low-level and long-term exposure. There is growing evidence that MeHg at environmentally relevant concentrations can affect the health of biota in the ecosystem. Although extensive in vivo and in vitro studies have demonstrated that the disruption of redox homeostasis and microtube assembly is mainly responsible for mercurial toxicity leading to adverse health outcomes, it is still unclear whether we could quantitively determine the occurrence of interaction between mercurial and thiols and/or selenols groups of proteins linked directly to outcomes, especially at very low levels of exposure. Furthermore, intracellular calcium homeostasis, cytoskeleton, mitochondrial function, oxidative stress, neurotransmitter release, and DNA methylation may be the targets of mercury compounds; however, the primary targets associated with the adverse outcomes remain to be elucidated. Considering these knowledge gaps, in this article, we conducted a comprehensive review of mercurial toxicity, focusing mainly on the mechanism, and genes/proteins expression. We speculated that comprehensive analyses of transcriptomics, proteomics, and metabolomics could enhance interpretation of "omics" profiles, which may reveal specific biomarkers obviously correlated with specific pathways that mediate selective neurotoxicity.
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Affiliation(s)
- Bolun Kang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012 Beijing, China
| | - Jinghan Wang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012 Beijing, China
| | - Shaojuan Guo
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012 Beijing, China
| | - Lixin Yang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012 Beijing, China.
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Baia-da-Silva DC, Mendes PFS, Silva DCBD, Chemelo VS, Bittencourt LO, Padilha PM, Oriá RB, Aschner M, Lima RR. What does scientometry tell us about mercury toxicology and its biological impairments? Heliyon 2024; 10:e27526. [PMID: 38586377 PMCID: PMC10998116 DOI: 10.1016/j.heliyon.2024.e27526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 02/29/2024] [Accepted: 03/01/2024] [Indexed: 04/09/2024] Open
Abstract
Mercury is a toxic pollutant that poses risks to both human and environmental health, making it a pressing public health concern. This study aimed to summarize the knowledge on mercury toxicology and the biological impairments caused by exposure to mercury in experimental studies and/or diagnosis in humans. The research was conducted on the main collection of Web of Science, employing as a methodological tool a bibliometric analysis. The selected articles were analyzed, and extracted data such as publication year, journal, author, title, number of citations, corresponding author's country, keywords, and the knowledge mapping was performed about the type of study, chemical form of mercury, exposure period, origin of exposure, tissue/fluid of exposure measurement, mercury concentration, evaluation period (age), mercury effect, model experiments, dose, exposure pathway, and time of exposure. The selected articles were published between 1965 and 2021, with Clarkson TW being the most cited author who has also published the most articles. A total of 38% of the publications were from the USA. These studies assessed the prenatal and postnatal effects of mercury, emphasizing the impact of methylmercury on neurodevelopment, including motor and cognitive evaluations, the association between mercury and autism, and an evaluation of its protective effects against mercury toxicity. In observational studies, the blood, umbilical cord, and hair were the most frequently used for measuring mercury levels. Our data analysis reveals that mercury neurotoxicology has been extensively explored, but the association among the outcomes evaluated in experimental studies has yet to be strengthened. Providing metric evidence on what is unexplored allows for new studies that may help governmental and non-governmental organizations develop guidelines and policies.
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Affiliation(s)
- Daiane Claydes Baia-da-Silva
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, PA, Brazil
| | - Paulo Fernando Santos Mendes
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, PA, Brazil
| | - Diane Cleydes Baia da Silva
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, PA, Brazil
| | - Victória Santos Chemelo
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, PA, Brazil
| | - Leonardo Oliveira Bittencourt
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, PA, Brazil
| | - Pedro Magalhães Padilha
- School of Veterinary Medicine and Animal Science, Institute of Biosciences, São Paulo State University, Botucatu, SP, Brazil
| | - Reinaldo Barreto Oriá
- Laboratory of Tissue Healing, Ontogeny and Nutrition, Department of Morphology, School of Medicine, Institute of Biomedicine, Federal University of Ceara, Fortaleza, CE, Brazil
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Rafael Rodrigues Lima
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, PA, Brazil
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Oguro A, Fujiyama T, Ishihara Y, Kataoka C, Yamamoto M, Eto K, Komohara Y, Imaoka S, Sakuragi T, Tsuji M, Shibata E, Kotake Y, Yamazaki T. Maternal DHA intake in mice increased DHA metabolites in the pup brain and ameliorated MeHg-induced behavioral disorder. J Lipid Res 2023; 64:100458. [PMID: 37838304 PMCID: PMC10656226 DOI: 10.1016/j.jlr.2023.100458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 10/05/2023] [Accepted: 10/07/2023] [Indexed: 10/16/2023] Open
Abstract
Although pregnant women's fish consumption is beneficial for the brain development of the fetus due to the DHA in fish, seafood also contains methylmercury (MeHg), which adversely affects fetal brain development. Epidemiological studies suggest that high DHA levels in pregnant women's sera may protect the fetal brain from MeHg-induced neurotoxicity, but the underlying mechanism is unknown. Our earlier study revealed that DHA and its metabolite 19,20-dihydroxydocosapentaenoic acid (19,20-DHDP) produced by cytochrome P450s (P450s) and soluble epoxide hydrolase (sEH) can suppress MeHg-induced cytotoxicity in mouse primary neuronal cells. In the present study, DHA supplementation to pregnant mice suppressed MeHg-induced impairments of pups' body weight, grip strength, motor function, and short-term memory. DHA supplementation also suppressed MeHg-induced oxidative stress and the decrease in the number of subplate neurons in the cerebral cortex of the pups. DHA supplementation to dams significantly increased the DHA metabolites 19,20-epoxydocosapentaenoic acid (19,20-EDP) and 19,20-DHDP as well as DHA itself in the fetal and infant brains, although the expression levels of P450s and sEH were low in the fetal brain and liver. DHA metabolites were detected in the mouse breast milk and in human umbilical cord blood, indicating the active transfer of DHA metabolites from dams to pups. These results demonstrate that DHA supplementation increased DHA and its metabolites in the mouse pup brain and alleviated the effects of MeHg on fetal brain development. Pregnant women's intake of fish containing high levels of DHA (or DHA supplementation) may help prevent MeHg-induced neurotoxicity in the fetus.
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Affiliation(s)
- Ami Oguro
- Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
| | - Taichi Fujiyama
- Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Yasuhiro Ishihara
- Program of Biomedical Science, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | | | | | - Komyo Eto
- National Institute for Minamata Disease, Kumamoto, Japan
| | - Yoshihiro Komohara
- Department of Cell Pathology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Susumu Imaoka
- Department of Biomedical Sciences, School of Biological and Environmental Sciences, Kwansei Gakuin University, Hyogo, Japan
| | - Toshihide Sakuragi
- Department of Environmental Health, School of Medicine, University of Occupational and Environmental Health, Fukuoka, Japan; Department of Obstetrics and Gynecology, School of Medicine, University of Occupational and Environmental Health, Fukuoka, Japan
| | - Mayumi Tsuji
- Department of Environmental Health, School of Medicine, University of Occupational and Environmental Health, Fukuoka, Japan
| | - Eiji Shibata
- Department of Obstetrics and Gynecology, Dokkyo Medical University, Tochigi, Japan
| | - Yaichiro Kotake
- Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Takeshi Yamazaki
- Program of Life and Environmental Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
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Wang R, Guo S, Kang B, Yang L. Toxicogenomic signatures associated with methylmercury induced developmental toxicity in the zebrafish embryos. CHEMOSPHERE 2023; 313:137380. [PMID: 36435318 DOI: 10.1016/j.chemosphere.2022.137380] [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: 09/12/2022] [Revised: 11/21/2022] [Accepted: 11/22/2022] [Indexed: 06/16/2023]
Abstract
Methylmercury (MeHg) is a toxicant with adverse effects on embryogenesis from fish to man. The developmental outcomes of MeHg are well understood, but molecular understanding of toxicity is rather limited. We performed here a genome-wide transcriptional analyses of 6, 30, and 50 μg/L MeHg exposed zebrafish embryos from 4 to 72 h post-fertilization (hpf) using RNA-sequencing and microarray, and conducted a systematical comparison of MeHg-induced transcriptomic responses reported in this and our previous studies. We observed MeHg significantly to disrupt expression of 1050, 1931, and 2996 genes, respectively including gene ontologies in terms of visual and sensory perception, phototransduction, ferroptosis, and GABAergic synapse. Significantly altered genes were associated with ontology categorized into metabolism, such as fatty acid, amino acid, and glutathione metabolism across all experiments. Expression of genes involved in Wnt, Shh, and Notch signaling pathways previously demonstrated to be crucial for development was changed at varying levels dependent on exposure concentrations and durations. Our findings show MeHg significantly to affect expression of genes associated with tissue and/or organs developmental processing including eye, lateral line, fins, and brain, especially in embryos exposed to 6 μg/L, which did not cause obviously toxic effects on zebrafish embryos. We obtain 21 genes being significantly altered by MeHg in a concentration and stage independent manner, and might be served as signatures for developmental toxicity and/or teratogenic effects.
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Affiliation(s)
- Ruihong Wang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012, Beijing, China
| | - Shaojuan Guo
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012, Beijing, China
| | - Bolun Kang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012, Beijing, China
| | - Lixin Yang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012, Beijing, China.
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Lee M, Kim EJ, Kim MJ, Yum MS. Rapamycin Cannot Reduce Seizure Susceptibility in Infantile Rats with Malformations of Cortical Development Lacking mTORC1 Activation. Mol Neurobiol 2022; 59:7439-7449. [PMID: 36194361 DOI: 10.1007/s12035-022-03033-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 09/04/2022] [Indexed: 11/28/2022]
Abstract
The mechanistic target of the rapamycin (mTOR) pathway is involved in cortical development. However, the efficacy of mTOR inhibitors in malformations of cortical dysplasia (MCD) outside of the tuberous sclerosis complex is unknown. We selected the MCD rat model with prenatal MAM exposure to test the efficacy of mTOR inhibitors in MCDs. We explored the early cortical changes of mTOR pathway protein expression in rats aged P15. We also monitored the early treatment effect of the mTOR inhibitor, rapamycin, on N-methyl-D-aspartate (NMDA)-induced spasms at P15 and their behavior in the juvenile stage. In vivo MR spectroscopy was performed after rapamycin treatment and compared with vehicle controls. There was no difference in mTORC1 pathway protein expression between MAM-exposed MCD rats and controls at P15, and prolonged treatment of rapamycin had no impact on NMDA-induced spasms despite poor weight gain. Prenatal MAM-exposed juvenile rats treated with rapamycin showed increased social approaching and freezing behavior during habituation. MR spectroscopy showed altered neurometabolites, including Gln, Glu+Gln, Tau, and Cr. Despite behavioral changes and in vivo neurometabolic alteration with early prolonged rapamycin treatment, rapamycin had no effect on spasms susceptibility in prenatal MAM-exposed infantile rats with MCD without mTORC1 activation. For MAM-exposed MCD rats without mTORC1 activation, treatment options outside of mTOR pathway inhibitors should be explored.
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Affiliation(s)
- Minyoung Lee
- Department of Pediatrics, University of Ulsan College of Medicine, Seoul, 05505, Korea.,Asan Medical Center, Asan Institute for Life Sciences, Seoul, 05505, Korea
| | - Eun-Jin Kim
- Department of Pediatrics, University of Ulsan College of Medicine, Seoul, 05505, Korea.,Asan Medical Center, Asan Institute for Life Sciences, Seoul, 05505, Korea
| | - Min-Jee Kim
- Department of Pediatrics, Asan Medical Center Children's Hospital, 88 Olympic-ro, Songpa-ku, Seoul, 05505, Korea
| | - Mi-Sun Yum
- Department of Pediatrics, University of Ulsan College of Medicine, Seoul, 05505, Korea. .,Department of Pediatrics, Asan Medical Center Children's Hospital, 88 Olympic-ro, Songpa-ku, Seoul, 05505, Korea.
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Koch K, Bartmann K, Hartmann J, Kapr J, Klose J, Kuchovská E, Pahl M, Schlüppmann K, Zühr E, Fritsche E. Scientific Validation of Human Neurosphere Assays for Developmental Neurotoxicity Evaluation. FRONTIERS IN TOXICOLOGY 2022; 4:816370. [PMID: 35295221 PMCID: PMC8915868 DOI: 10.3389/ftox.2022.816370] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 01/21/2022] [Indexed: 01/06/2023] Open
Abstract
There is a call for a paradigm shift in developmental neurotoxicity (DNT) evaluation, which demands the implementation of faster, more cost-efficient, and human-relevant test systems than current in vivo guideline studies. Under the umbrella of the Organisation for Economic Co-operation and Development (OECD), a guidance document is currently being prepared that instructs on the regulatory use of a DNT in vitro battery (DNT IVB) for fit-for-purpose applications. One crucial issue for OECD application of methods is validation, which for new approach methods (NAMs) requires novel approaches. Here, mechanistic information previously identified in vivo, as well as reported neurodevelopmental adversities in response to disturbances on the cellular and tissue level, are of central importance. In this study, we scientifically validate the Neurosphere Assay, which is based on human primary neural progenitor cells (hNPCs) and an integral part of the DNT IVB. It assesses neurodevelopmental key events (KEs) like NPC proliferation (NPC1ab), radial glia cell migration (NPC2a), neuronal differentiation (NPC3), neurite outgrowth (NPC4), oligodendrocyte differentiation (NPC5), and thyroid hormone-dependent oligodendrocyte maturation (NPC6). In addition, we extend our work from the hNPCs to human induced pluripotent stem cell-derived NPCs (hiNPCs) for the NPC proliferation (iNPC1ab) and radial glia assays (iNPC2a). The validation process we report for the endpoints studied with the Neurosphere Assays is based on 1) describing the relevance of the respective endpoints for brain development, 2) the confirmation of the cell type-specific morphologies observed in vitro, 3) expressions of cell type-specific markers consistent with those morphologies, 4) appropriate anticipated responses to physiological pertinent signaling stimuli and 5) alterations in specific in vitro endpoints upon challenges with confirmed DNT compounds. With these strong mechanistic underpinnings, we posit that the Neurosphere Assay as an integral part of the DNT in vitro screening battery is well poised for DNT evaluation for regulatory purposes.
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Affiliation(s)
- Katharina Koch
- IUF—Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Kristina Bartmann
- IUF—Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Julia Hartmann
- IUF—Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Julia Kapr
- IUF—Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Jördis Klose
- IUF—Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Eliška Kuchovská
- IUF—Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Melanie Pahl
- IUF—Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Kevin Schlüppmann
- IUF—Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Etta Zühr
- IUF—Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Ellen Fritsche
- IUF—Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
- Medical Faculty, Heinrich-Heine-University, Duesseldorf, Germany
- *Correspondence: Ellen Fritsche,
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The Impact of Oxidative Stress of Environmental Origin on the Onset of Placental Diseases. Antioxidants (Basel) 2022; 11:antiox11010106. [PMID: 35052610 PMCID: PMC8773163 DOI: 10.3390/antiox11010106] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 12/28/2021] [Accepted: 12/29/2021] [Indexed: 12/28/2022] Open
Abstract
Oxidative stress (OS) plays a pivotal role in placental development; however, abnormal loads in oxidative stress molecules may overwhelm the placental defense mechanisms and cause pathological situations. The environment in which the mother evolves triggers an exposure of the placental tissue to chemical, physical, and biological agents of OS, with potential pathological consequences. Here we shortly review the physiological and developmental functions of OS in the placenta, and present a series of environmental pollutants inducing placental oxidative stress, for which some insights regarding the underlying mechanisms have been proposed, leading to a recapitulation of the noxious effects of OS of environmental origin upon the human placenta.
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Abbott LC, Nigussie F. Mercury Toxicity and Neurogenesis in the Mammalian Brain. Int J Mol Sci 2021; 22:ijms22147520. [PMID: 34299140 PMCID: PMC8305137 DOI: 10.3390/ijms22147520] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/12/2021] [Accepted: 07/05/2021] [Indexed: 01/21/2023] Open
Abstract
The mammalian brain is formed from billions of cells that include a wide array of neuronal and glial subtypes. Neural progenitor cells give rise to the vast majority of these cells during embryonic, fetal, and early postnatal developmental periods. The process of embryonic neurogenesis includes proliferation, differentiation, migration, the programmed death of some newly formed cells, and the final integration of differentiated neurons into neural networks. Adult neurogenesis also occurs in the mammalian brain, but adult neurogenesis is beyond the scope of this review. Developing embryonic neurons are particularly susceptible to neurotoxicants and especially mercury toxicity. This review focused on observations concerning how mercury, and in particular, methylmercury, affects neurogenesis in the developing mammalian brain. We summarized information on models used to study developmental mercury toxicity, theories of pathogenesis, and treatments that could be used to reduce the toxic effects of mercury on developing neurons.
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Affiliation(s)
- Louise C. Abbott
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, 4458 TAMU, College Station, TX 77843-4458, USA
- Correspondence: ; Tel.: +1-541-254-0779
| | - Fikru Nigussie
- College of Veterinary Medicine, Oregon State University, 700 SW 30th Street, Corvallis, OR 97331, USA;
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Diana Neely M, Xie S, Prince LM, Kim H, Tukker AM, Aschner M, Thimmapuram J, Bowman AB. Single cell RNA sequencing detects persistent cell type- and methylmercury exposure paradigm-specific effects in a human cortical neurodevelopmental model. Food Chem Toxicol 2021; 154:112288. [PMID: 34089799 DOI: 10.1016/j.fct.2021.112288] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 05/14/2021] [Accepted: 05/15/2021] [Indexed: 12/13/2022]
Abstract
The developing human brain is uniquely vulnerable to methylmercury (MeHg) resulting in lasting effects especially in developing cortical structures. Here we assess by single-cell RNA sequencing (scRNAseq) persistent effects of developmental MeHg exposure in a differentiating cortical human-induced pluripotent stem cell (hiPSC) model which we exposed to in vivo relevant and non-cytotoxic MeHg (0.1 and 1.0 μM) concentrations. The cultures were exposed continuously for 6 days either once only during days 4-10, a stage representative of neural epithelial- and radial glia cells, or twice on days 4-10 and days 14-20, a somewhat later stage which includes intermediate precursors and early postmitotic neurons. After the completion of MeHg exposure the cultures were differentiated further until day 38 and then assessed for persistent MeHg-induced effects by scRNAseq. We report subtle, but significant changes in the population size of different cortical cell types/stages and cell cycle. We also observe MeHg-dependent differential gene expression and altered biological processes as determined by Gene Ontology analysis. Our data demonstrate that MeHg results in changes in gene expression in human developing cortical neurons that manifest well after cessation of exposure and that these changes are cell type-, developmental stage-, and exposure paradigm-specific.
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Affiliation(s)
- M Diana Neely
- Dept of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Shaojun Xie
- Bioinformatics Core, Purdue University, West Lafayette, IN, USA
| | - Lisa M Prince
- School of Health Sciences, Purdue University, West Lafayette, IN, USA
| | - Hyunjin Kim
- School of Health Sciences, Purdue University, West Lafayette, IN, USA
| | - Anke M Tukker
- School of Health Sciences, Purdue University, West Lafayette, IN, USA
| | - Michael Aschner
- Dept of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
| | | | - Aaron B Bowman
- Dept of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA; School of Health Sciences, Purdue University, West Lafayette, IN, USA.
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Mechanisms of oxidative stress in methylmercury-induced neurodevelopmental toxicity. Neurotoxicology 2021; 85:33-46. [PMID: 33964343 DOI: 10.1016/j.neuro.2021.05.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 05/02/2021] [Accepted: 05/03/2021] [Indexed: 12/15/2022]
Abstract
Methylmercury (MeHg) is a long-lasting organic environmental pollutant that poses a great threat to human health. Ingestion of seafood containing MeHg is the most important way by which it comes into contact with human body, where the central nervous system (CNS) is the primary target of MeHg toxicity. During periods of pre-plus postnatal, in particular, the brain of offspring is vulnerable to specific developmental insults that result in abnormal neurobehavioral development, even without symptoms in mothers. While many studies on neurotoxic effects of MeHg on the developing brain have been conducted, the mechanisms of oxidative stress in MeHg-induced neurodevelopmental toxicity is less clear. Hitherto, no single process can explain the many effects observed in MeHg-induced neurodevelopmental toxicity. This review summarizes the possible mechanisms of oxidative stress in MeHg-induced neurodevelopmental toxicity, highlighting modulation of Nrf2/Keap1/Notch1, PI3K/AKT, and PKC/MAPK molecular pathways as well as some preventive drugs, and thus contributes to the discovery of endogenous and exogenous molecules that can counteract MeHg-induced neurodevelopmental toxicity.
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Tong M, Yu J, Liu M, Li Z, Wang L, Yin C, Ren A, Chen L, Jin L. Total mercury concentration in placental tissue, a good biomarker of prenatal mercury exposure, is associated with risk for neural tube defects in offspring. ENVIRONMENT INTERNATIONAL 2021; 150:106425. [PMID: 33581418 DOI: 10.1016/j.envint.2021.106425] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 01/26/2021] [Accepted: 01/27/2021] [Indexed: 06/12/2023]
Abstract
OBJECTIVE To examine the role of total mercury (T-Hg) in placenta as a biomarker of prenatal mercury (Hg) exposure and determine the association between prenatal Hg exposure and risk for neural tube defects (NTDs) in offspring. METHODS Total Hg concentrations in placental tissue were detected in 408 NTD cases and 593 healthy controls enrolled in Shanxi province in northern China. Methylmercury (MeHg) and T-Hg were also detected in the umbilical cord of 147 NTD cases and 140 healthy controls. In addition, MeHg and T-Hg were detected in fetal kidney, liver, and brain tissues of 51 NTD cases. Spearman's rank correlation (rs) was used to evaluate the correlations between placental T-Hg and T-Hg in umbilical cord and fetal kidney, liver, and brain tissues. The Wilcoxon rank-sum test was used to compare T-Hg amounts between case and control groups. Logistic regression was used to examine the association between placental T-Hg and risk for NTDs. RESULTS Placental T-Hg was significantly correlated with T-Hg in umbilical cord (rs = 0.479), kidney (rs = 0.718), liver (rs = 0.656), and brain (rs = 0.512) tissues (all p < 0.001). The median (25th percentile-75th percentile) concentration for placental T-Hg in the NTD case group was 8.91 (5.00-17.1) ng/g dry weight (d.w.), significantly higher than that in the healthy control group (4.99 [3.26-7.93] ng/g d.w., p < 0.001). After adjusting for potential confounders, higher levels of T-Hg in placenta were associated with increased risk for NTDs in offspring (OR = 1.76, 95% CI: 1.13-2.76), and a dose-response relationship was found (p < 0.001). CONCLUSION The concentration of T-Hg in placenta is a good biomarker for estimating prenatal Hg exposure, which is associated with increased risk for NTDs.
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Affiliation(s)
- Mingkun Tong
- Institute of Reproductive and Child Health, Peking University/Key Laboratory of Reproductive Health, the National Health Commission of the People's Republic of China; Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, China
| | - Jingru Yu
- Institute of Reproductive and Child Health, Peking University/Key Laboratory of Reproductive Health, the National Health Commission of the People's Republic of China; Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, China
| | - Ming Liu
- State Environmental Protection Key Laboratory of Urban Ecological Environment Simulation and Protection, South China Institute of Environmental Sciences, Ministry of Ecology and Environment of the People's Republic of China, Guangzhou 510655, China
| | - Zhiwen Li
- Institute of Reproductive and Child Health, Peking University/Key Laboratory of Reproductive Health, the National Health Commission of the People's Republic of China; Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, China
| | - Linlin Wang
- Institute of Reproductive and Child Health, Peking University/Key Laboratory of Reproductive Health, the National Health Commission of the People's Republic of China; Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, China
| | - Chenghong Yin
- Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing 100026, China
| | - Aiguo Ren
- Institute of Reproductive and Child Health, Peking University/Key Laboratory of Reproductive Health, the National Health Commission of the People's Republic of China; Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, China
| | - Laiguo Chen
- State Environmental Protection Key Laboratory of Urban Ecological Environment Simulation and Protection, South China Institute of Environmental Sciences, Ministry of Ecology and Environment of the People's Republic of China, Guangzhou 510655, China.
| | - Lei Jin
- Institute of Reproductive and Child Health, Peking University/Key Laboratory of Reproductive Health, the National Health Commission of the People's Republic of China; Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, China.
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12
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Environmentally relevant developmental methylmercury exposures alter neuronal differentiation in a human-induced pluripotent stem cell model. Food Chem Toxicol 2021; 152:112178. [PMID: 33831500 DOI: 10.1016/j.fct.2021.112178] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 03/15/2021] [Accepted: 03/30/2021] [Indexed: 12/14/2022]
Abstract
Developmental methylmercury (MeHg) exposure selectively targets the cerebral and cerebellar cortices, as seen by disruption of cytoarchitecture and glutamatergic (GLUergic) neuron hypoplasia. To begin to understand the mechanisms of this loss of GLUergic neurons, we aimed to develop a model of developmental MeHg neurotoxicity in human-induced pluripotent stem cells differentiating into cortical GLUergic neurons. Three dosing paradigms at 0.1 μM and 1.0 μM MeHg, which span different stages of neurodevelopment and reflect toxicologically relevant accumulation levels seen in human studies and mammalian models, were established. With these exposure paradigms, no changes were seen in commonly studied endpoints of MeHg toxicity, including viability, proliferation, and glutathione levels. However, MeHg exposure induced changes in mitochondrial respiration and glycolysis and in markers of neuronal differentiation. Our novel data suggests that GLUergic neuron hypoplasia seen with MeHg toxicity may be due to the partial inhibition of neuronal differentiation, given the increased expression of the early dorsal forebrain marker FOXG1 and corresponding decrease in expression on neuronal markers MAP2 and DCX and the deep layer cortical neuronal marker TBR1. Future studies should examine the persistent and latent functional effects of this MeHg-induced disruption of neuronal differentiation as well as transcriptomic and metabolomic alterations that may mediate MeHg toxicity.
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13
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Davidson PW, Myers GJ, Shamlaye C. Principles of studying low-level neurotoxic exposures in children: using the Seychelles Child Development Study of methyl mercury as a prototype. Neurotoxicology 2021; 81:307-314. [PMID: 33741114 DOI: 10.1016/j.neuro.2020.09.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Epidemiological studies to determine the impact of low level toxic exposure on child development are important in guiding clinical and public health action. However, carrying out such studies and interpreting their findings presents a number of significant challenges to the investigators. First, they must find a cohort with suitable exposure, select a biomarker that will accurately determine the level of exposure and determine the endpoints that are most likely to detect subtle differences in neurodevelopment. Following that, the logistics of the study must be organised and collaboration established with the local population and health authorities. To accurately interpret the data, they must also accurately determine covariates that impact child development. After the data are collected, interpreting the findings presents a further challenge. Throughout this process, the study must adhere to fundamental epidemiological principles and clearly defined statistical approaches. This paper discusses those principles and uses the Seychelles Child Development Study to show how one epidemiological study addressed them.
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Affiliation(s)
- Philip W Davidson
- Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA.
| | - Gary J Myers
- Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA; Department of Neurology, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
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14
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Scoville SA, Varian-Ramos CW, Adkins GA, Swaddle JP, Saha MS, Cristol DA. Mercury delays cerebellar development in a model songbird species, the zebra finch. ECOTOXICOLOGY (LONDON, ENGLAND) 2020; 29:1128-1137. [PMID: 32827288 DOI: 10.1007/s10646-020-02270-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/11/2020] [Indexed: 06/11/2023]
Abstract
Mercury exposure can disrupt development of the cerebellum, part of the brain essential for coordination of movement through a complex environment, including flight. In precocial birds, such as fowl, the cerebellum develops embryonically, and the chick is capable of leaving the nest within hours of hatching. However, most birds, including all songbirds, are altricial, and spend weeks in the nest between hatching and fledging. The objective of this study was to describe the normal development of the cerebellum in a model altricial songbird so as to determine the effect of exposure to mercury on cerebellar maturation. Adult zebra finch (Taeniopygia guttata) pairs were fed either a control diet, or a diet augmented with one of four treatment-levels of methylmercury (0.3-2.4 μg/g wet weight), and their offspring, the subjects of this study, were fed the same diet by parents. We documented, for the first time, the schedule of cerebellar development in an altricial bird, and compared stages of development among methylmercury-exposed groups. For all treatments of methylmercury, the age of completion of cellular migration was later than for control zebra finches, indicating a delay in cerebellar maturation. Displaced (heterotopic) Purkinje neurons, a pathology typical of methylmercury exposure in developing vertebrate brains, were more numerous in methylmercury-exposed birds, and persisted at least until the age of independence. Delays in maturation of the cerebellum could delay fledging in altricial bird species, with potential serious implications for the fitness of exposed individuals, as predation rates in the nest are often very high.
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Affiliation(s)
- Sheila A Scoville
- Department of Pathology and Anatomy, Eastern Virginia Medical School, Norfolk, VA, 23507, USA
| | - Claire W Varian-Ramos
- Department of Biology, William & Mary, Williamsburg, VA, 23185, USA
- Biology Department, Colorado State University - Pueblo, Pueblo, CO, 81001, USA
| | - G Alden Adkins
- Department of Biology, William & Mary, Williamsburg, VA, 23185, USA
- University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - John P Swaddle
- Department of Biology, William & Mary, Williamsburg, VA, 23185, USA
| | - Margaret S Saha
- Department of Biology, William & Mary, Williamsburg, VA, 23185, USA
| | - Daniel A Cristol
- Department of Biology, William & Mary, Williamsburg, VA, 23185, USA.
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15
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Pregnant rats exposed to low-level methylmercury exhibit cerebellar synaptic and neuritic remodeling during the perinatal period. Arch Toxicol 2020; 94:1335-1347. [DOI: 10.1007/s00204-020-02696-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 03/02/2020] [Indexed: 12/14/2022]
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16
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Shah-Kulkarni S, Lee S, Jeong KS, Hong YC, Park H, Ha M, Kim Y, Ha EH. Prenatal exposure to mixtures of heavy metals and neurodevelopment in infants at 6 months. ENVIRONMENTAL RESEARCH 2020; 182:109122. [PMID: 32069757 DOI: 10.1016/j.envres.2020.109122] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 01/06/2020] [Accepted: 01/06/2020] [Indexed: 06/10/2023]
Abstract
BACKGROUND Exposure to mixture of neurotoxic metals such as lead, mercury and cadmium occurs at a specific point of time. When exposed to metal mixtures, one metal may act as an agonist or antagonist to another metal. Thus, it is important to study the effects of exposure to a combination of metals on children's development using advance statistical methods. OBJECTIVES In this study, we explored the effects of prenatal metal exposure including lead, mercury and cadmium in early pregnancy (12-20 weeks), late pregnancy (>28 weeks), and at birth on neurodevelopment of infants at 6 months of age. METHODS We included 523 eligible mother-child pairs from the mothers and children environmental health (MOCEH) study, a prospective birth cohort study in Korea. We used linear regression, Bayesian kernel machine regression (BKMR) and generalized additive models (GAM), to evaluate the effects of exposure to metal mixtures on neurodevelopment of infants aged 6 months. The Korean version of Bayley scale of infant and toddler development-II was used to measure the child's neurodevelopment. RESULTS Linear regression models showed a significant negative effect of lead exposure during late pregnancy on the mental development index (MDI) [β = -2.51 (-4.92, -0.10)] scores of infants aged 6 months following co-exposure to mercury. Further, linear regression analysis showed a significant interaction between late pregnancy lead and mercury concentrations. BKMR analysis showed similar results as those obtained in linear regression models. These results were also replicated in the GAM. Stratification analysis showed that greater than 50 percentile concentration of mercury in late pregnancy potentiated the adverse effects of lead in late pregnancy on MDI [β = -4.33 (-7.66, -1.00)] and psychomotor development index (PDI) [β = -5.30 (-9.13, -1.46)] at 6 months of age. Prenatal cadmium exposure did not show a significant association with MDI and PDI at 6 months in the linear regression or BKMR analysis. CONCLUSION Based on all the statistical methods used, we demonstrated the effect of combined exposure to metals on the neurodevelopment of infants aged 6 months, with significant interaction between lead and mercury.
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Affiliation(s)
- Surabhi Shah-Kulkarni
- Department of Occupational and Environmental Medicine, Ewha Womans University College of Medicine, Seoul, Republic of Korea
| | - Seulbi Lee
- Department of Occupational and Environmental Medicine, Ewha Womans University College of Medicine, Seoul, Republic of Korea
| | - Kyoung Sook Jeong
- Department of Occupational and Environmental Medicine, Hallym University Sacred Heart Hospital, Gyeonggido, Republic of Korea
| | - Yun-Chul Hong
- Department of Preventive Medicine, College of Medicine, Seoul National University, Seoul, Republic of Korea
| | - Hyesook Park
- Department of Preventive Medicine, Ewha Womans University College of Medicine, Seoul, Republic of Korea
| | - Mina Ha
- Department of Preventive Medicine, Dankook University College of Medicine, Cheonan, Republic of Korea
| | - Yangho Kim
- Department of Occupational and Environmental Medicine, University of Ulsan College of Medicine, Ulsan University Hospital, Ulsan, Republic of Korea
| | - Eun-Hee Ha
- Department of Occupational and Environmental Medicine, Ewha Womans University College of Medicine, Seoul, Republic of Korea.
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17
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O'Donoghue JL, Watson GE, Brewer R, Zareba G, Eto K, Takahashi H, Marumoto M, Love T, Harrington D, Myers GJ. Neuropathology associated with exposure to different concentrations and species of mercury: A review of autopsy cases and the literature. Neurotoxicology 2020; 78:88-98. [PMID: 32092311 DOI: 10.1016/j.neuro.2020.02.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 02/16/2020] [Accepted: 02/21/2020] [Indexed: 11/20/2022]
Abstract
BACKGROUND Human exposure to mercury (Hg) is widespread and both organic and inorganic Hg are routinely found in the human brain. Millions of people are exposed to methyl Hg (MeHg) due to the consumption of fish and to inorganic Hg from dental amalgams, small scale gold mining operations, use of Hg containing products, or their occupations. Neuropathology information associated with exposures to different species of Hg is primarily based on case reports of single individuals or collections of case studies involving a single species of Hg at toxic exposure levels such as occurred in Japan and Iraq. METHODS/RESULTS This study brings together information on the neuropathological findings and deposition of Hg in the central nervous system of people exposed to different species of Hg at varying concentrations. The low dose exposures were lifetime exposures while the high dose exposures were generally acute or short term by different exposure routes with survival lasting various lengths of time. Total and inorganic Hg deposits were identified in formalin-fixed, paraffin embedded tissues from both low and high exposure Hg cases. Low concentration exposures were studied in adult brains from Rochester, New York (n = 4) and the Republic of Seychelles (n = 17). Rochester specimens had mean total Hg concentrations of 16-18 ppb in the calcarine, rolandic, and cerebellar cortices. Inorganic Hg averaged between 5-6 ppb or 30-37% for the cerebral and cerebellar cortices of the Rochester subjects. Total Hg was approximately 10-fold higher in specimens from Seychelles, where consumption of ocean fish is high and consequently results in exposure to MeHg. The predominant Hg species was MeHg in both the Rochester and Seychelles brain specimens. Histologically, cerebral and cerebellar cortices from Rochester and Seychelles specimens were indistinguishable. High concentration exposures were studied in brains from four adults who were autopsied at variable time periods after exposure to organic Hg (methyl or dimethyl) or inorganic Hg (inhaled vapor or intravenous injection of metallic Hg). In contrast to the Seychellois adults, these individuals had acute or subacute exposures to lethal or significantly higher concentrations. The pattern of Hg deposition differed between subjects with high organic Hg exposure and high inorganic Hg exposure. In the organic Hg cases, glia (astrocytes and microglia) and endothelial cells accumulated more Hg than neurons and there were minimal Hg deposits in cerebellar granule and Purkinje cells, anterior horn motor neurons, and neocortical pyramidal neurons. In the inorganic Hg cases, Hg was seen predominantly in neurons, vascular walls, brainstem, and cerebellar and cerebral deep gray nuclei. The presence of inorganic Hg in neural and neural supporting cells in the four high exposure Hg cases was not closely correlated with cellular pathology; particularly in the inorganic Hg cases. CONCLUSIONS Different Hg species are associated with differing neuropathological patterns. No neuropathological abnormalities were present in the brains of either Rochester or Seychelles residents despite substantial differences in dietary MeHg exposure. Increasing concentrations of inorganic Hg were present in the brain of relatively low exposure subjects with increasing age.
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Affiliation(s)
- John L O'Donoghue
- Department of Environmental Medicine, University of Rochester Medical Center, School of Medicine and Dentistry, Box EHSC, 601 Elmwood Ave, Rochester, NY 14642, United States.
| | - Gene E Watson
- Department of Environmental Medicine, University of Rochester Medical Center, School of Medicine and Dentistry, Box EHSC, 601 Elmwood Ave, Rochester, NY 14642, United States; Eastman Institute for Oral Health and Department of Pharmacology and Physiology, University of Rochester Medical Center, School of Medicine and Dentistry, Box 683, 601 Elmwood Ave, Rochester, NY, 14642, United States
| | - Rubell Brewer
- Victoria Hospital and the Ministry of Health, Seychelles
| | - Grazyna Zareba
- Department of Environmental Medicine, University of Rochester Medical Center, School of Medicine and Dentistry, Box EHSC, 601 Elmwood Ave, Rochester, NY 14642, United States
| | - Komyo Eto
- Formerly Director General, National Institute for Minamata Disease, Ministry of the Environment, 4058-18, Hama, Minamata City, Kumamoto Prefecture, 867-0008, Japan
| | - Hitoshi Takahashi
- Department of Pathology, Brain Research Institute, Niigata University, 1-757 Asahimachi, Chuo-ku, Niigata, 951-8585, Japan
| | - Masumi Marumoto
- Toxicologic Pathology Section, Department of Basic Medical Sciences, National Institute for Minamata Disease, Ministry of the Environment, 4058-18, Hama, Minamata City, Kumamoto Prefecture, 867-0008, Japan
| | - Tanzy Love
- Department of Biostatistics and Computational Biology, University of Rochester Medical Center, School of Medicine and Dentistry, Box 630, 601 Elmwood Ave, Rochester, NY, 14642, United States
| | - Donald Harrington
- Department of Biostatistics and Computational Biology, University of Rochester Medical Center, School of Medicine and Dentistry, Box 630, 601 Elmwood Ave, Rochester, NY, 14642, United States
| | - Gary J Myers
- Department of Environmental Medicine, University of Rochester Medical Center, School of Medicine and Dentistry, Box EHSC, 601 Elmwood Ave, Rochester, NY 14642, United States; Department of Neurology, Child Neurology, University of Rochester Medical Center, School of Medicine and Dentistry, Box 631, 601 Elmwood Avenue, Rochester, NY 14642, United States; Department of Pediatrics, University of Rochester Medical Center, School of Medicine and Dentistry, Box 631, 601 Elmwood Ave, Rochester, NY, 14642, United States
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18
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Gagnon-Chauvin A, Bastien K, Saint-Amour D. Environmental toxic agents: The impact of heavy metals and organochlorides on brain development. HANDBOOK OF CLINICAL NEUROLOGY 2020; 173:423-442. [PMID: 32958188 DOI: 10.1016/b978-0-444-64150-2.00030-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Exposure to environmental toxicants can have deleterious effects on the development of physical, cognitive, and mental health. Extensive laboratory and clinical studies have demonstrated how the developing brain is uniquely sensitive to toxic agents. This chapter focuses on the main neurologic impairments linked to prenatal and postnatal exposure to lead, methylmercury, and polychlorinated biphenyls, three legacy environmental contaminants whose neurotoxic effects have been extensively studied with respect to cognitive and behavioral development. The main cognitive, emotion regulation, sensory, and motor impairments in association with these contaminants are briefly reviewed, including the underlying neural mechanisms such as neuropathologic damages, brain neurotransmission, and endocrine system alterations. The use of neuroimaging as a novel tool to better understand how the brain is affected by exposure to environmental contaminants is also discussed.
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Affiliation(s)
- Avril Gagnon-Chauvin
- Department of Psychology, Université du Québec à Montréal, Montréal, QC, Canada; Research Centre, Centre Hospitalier Universitaire Sainte-Justine, Université de Montréal, Montréal, QC, Canada
| | - Kevin Bastien
- Department of Psychology, Université du Québec à Montréal, Montréal, QC, Canada; Research Centre, Centre Hospitalier Universitaire Sainte-Justine, Université de Montréal, Montréal, QC, Canada
| | - Dave Saint-Amour
- Department of Psychology, Université du Québec à Montréal, Montréal, QC, Canada; Research Centre, Centre Hospitalier Universitaire Sainte-Justine, Université de Montréal, Montréal, QC, Canada.
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19
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Ke B, Chen H, Ma L, Zingales S, Gong D, Hu D, Du L, Li M. Visualization of mercury(ii) accumulation in vivo using bioluminescence imaging with a highly selective probe. Org Biomol Chem 2019; 16:2388-2392. [PMID: 29560483 DOI: 10.1039/c8ob00398j] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Mercury is a highly toxic environmental pollutant that negatively affects human health. Thus, an in vivo method for noninvasive imaging of mercury(ii) and visualization of its accumulation within living systems would be advantageous. Herein, we describe a reaction-based bioluminescent probe for detection of mercury(ii) in vitro and accumulation in vivo. The application of this probe would help to shed light on the intricate contributions of mercury(ii) to various physiological and pathological processes.
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Affiliation(s)
- Bowen Ke
- Laboratory of Anaesthesiology & Critical Care Medicine, West China Brain Research Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Hui Chen
- Laboratory of Anaesthesiology & Critical Care Medicine, West China Brain Research Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China and Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (MOE), School of Pharmacy, Shandong University, Jinan, Shandong 250012, China.
| | - Lin Ma
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (MOE), School of Pharmacy, Shandong University, Jinan, Shandong 250012, China.
| | - Sarah Zingales
- Department of Chemistry and Physics, Armstrong State University, Savannah, GA 31419, USA
| | - Deying Gong
- Laboratory of Anaesthesiology & Critical Care Medicine, West China Brain Research Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Die Hu
- Laboratory of Anaesthesiology & Critical Care Medicine, West China Brain Research Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Lupei Du
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (MOE), School of Pharmacy, Shandong University, Jinan, Shandong 250012, China.
| | - Minyong Li
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (MOE), School of Pharmacy, Shandong University, Jinan, Shandong 250012, China.
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20
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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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21
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Abstract
Toxic chemicals, either from natural sources or man-made, are ubiquitous in our environment. Many of the synthetic chemicals make life more comfortable and therefore production continues to grow. Simultaneously with the increase in production, an increase in neurodevelopmental disorders has been observed. Some chemicals are not biodegradable or have a very long half-life time and, despite the fact that production of a number of those chemicals has been severely reduced, they are still ubiquitous in the environment. Fetal exposure to toxic chemicals is dependent on maternal exposure to those chemicals and the developing stage of the fetus. Human evidence from epidemiologic studies is described with regard to the effect of prenatal exposure to various groups of neurotoxicants (alcohol, particulate fine matter, metals, and endocrine disrupting chemicals) on neurobehavior development. Data indicate that prenatal exposure to alcohol, polycyclic aromatic hydrocarbons, lead, methylmercury (MeHg), organophosphate pesticides (OPPs), and polychlorinated biphenyl ethers (PBDEs) impair cognitive development, whereas exposure to alcohol, MeHg, organochlorine pesticides and OPPs, polychlorinated biphenyls, PBDEs, and bisphenol A increases the risk of developing either attention deficit/hyperactivity and/or autism spectrum disorders. Psychomotor development appears to be less affected. However, data are not conclusive, which may depend on the assessment of exposure and the exposure level, among other factors.
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Affiliation(s)
- Margot van de Bor
- Department of Environment and Health, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
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22
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MeHg Causes Ultrastructural Changes in Mitochondria and Autophagy in the Spinal Cord Cells of Chicken Embryo. J Toxicol 2018; 2018:8460490. [PMID: 30228816 PMCID: PMC6136469 DOI: 10.1155/2018/8460490] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 08/06/2018] [Indexed: 01/16/2023] Open
Abstract
Methylmercury (MeHg) is a known neurodevelopmental toxicant, which causes changes in various structures of the central nervous system (CNS). However, ultrastructural studies of its effects on the developing CNS are still scarce. Here, we investigated the effect of MeHg on the ultrastructure of the cells in spinal cord layers. Chicken embryos at E3 were treated in ovo with 0.1 μg MeHg/50 μL saline solution and analyzed at E10. Then, we used transmission electron microscopy (TEM) to identify possible damage caused by MeHg to the structures and organelles of the spinal cord cells. After MeHg treatment, we observed, in the spinal cord mantle layer, a significant number of altered mitochondria with external membrane disruptions, crest disorganization, swelling in the mitochondrial matrix, and vacuole formation between the internal and external mitochondrial membranes. We also observed dilations in the Golgi complex and endoplasmic reticulum cisterns and the appearance of myelin-like cytoplasmic inclusions. We observed no difference in the total mitochondria number between the control and MeHg-treated groups. However, the MeHg-treated embryos showed an increased number of altered mitochondria and a decreased number of mitochondrial fusion profiles. Additionally, unusual mitochondrial shapes were found in MeHg-treated embryos as well as autophagic vacuoles similar to mitophagic profiles. In addition, we observed autophagic vacuoles with amorphous, homogeneous, and electron-dense contents, similar to the autophagy. Our results showed, for the first time, the neurotoxic effect of MeHg on the ultrastructure of the developing spinal cord. Using TEM we demonstrate that changes in the endomembrane system, mitochondrial damage, disturbance in mitochondrial dynamics, and increase in mitophagy were caused by MeHg exposure.
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23
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Antunes Dos Santos A, Ferrer B, Marques Gonçalves F, Tsatsakis AM, Renieri EA, Skalny AV, Farina M, Rocha JBT, Aschner M. Oxidative Stress in Methylmercury-Induced Cell Toxicity. TOXICS 2018; 6:toxics6030047. [PMID: 30096882 PMCID: PMC6161175 DOI: 10.3390/toxics6030047] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 08/03/2018] [Accepted: 08/07/2018] [Indexed: 02/06/2023]
Abstract
Methylmercury (MeHg) is a hazardous environmental pollutant, which elicits significant toxicity in humans. The accumulation of MeHg through the daily consumption of large predatory fish poses potential health risks, and the central nervous system (CNS) is the primary target of toxicity. Despite well-described neurobehavioral effects (i.e., motor impairment), the mechanisms of MeHg-induced toxicity are not completely understood. However, several lines of evidence point out the oxidative stress as an important molecular mechanism in MeHg-induced intoxication. Indeed, MeHg is a soft electrophile that preferentially interacts with nucleophilic groups (mainly thiols and selenols) from proteins and low-molecular-weight molecules. Such interaction contributes to the occurrence of oxidative stress, which can produce damage by several interacting mechanisms, impairing the function of various molecules (i.e., proteins, lipids, and nucleic acids), potentially resulting in modulation of different cellular signal transduction pathways. This review summarizes the general aspects regarding the interaction between MeHg with regulators of the antioxidant response system that are rich in thiol and selenol groups such as glutathione (GSH), and the selenoenzymes thioredoxin reductase (TrxR) and glutathione peroxidase (Gpx). A particular attention is directed towards the role of the PI3K/Akt signaling pathway and the nuclear transcription factor NF-E2-related factor 2 (Nrf2) in MeHg-induced redox imbalance.
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Affiliation(s)
| | - Beatriz Ferrer
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| | - Filipe Marques Gonçalves
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| | - Aristides M Tsatsakis
- Laboratory of Toxicology, Medical School, University of Crete, 71003 Heraklion, Greece.
| | - Elisavet A Renieri
- Laboratory of Toxicology, Medical School, University of Crete, 71003 Heraklion, Greece.
| | - Anatoly V Skalny
- Department of Medical Elementology, Peoples' Friendship University of Russia (RUDN University), Moscow 150000, Russia.
- Laboratory of Biotechnology and Applied Bioelementology, Yaroslavl State University, Yaroslavl 150014, Russia.
- All-Russian Research Institute of Medicinal and Aromatic Plants (VILAR), Moscow 150000, Russia.
| | - Marcelo Farina
- Department of Biochemistry, Federal University of Santa Catarina, Florianopolis 88040-900, Santa Catarina, Brazil.
| | - João B T Rocha
- Department of Biochemistry, Federal University of Santa Maria, Santa Maria 97105-900, Rio Grande do Sul, Brazil.
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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24
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Tucker EK, Nowak RA. Methylmercury alters proliferation, migration, and antioxidant capacity in human HTR8/SV-neo trophoblast cells. Reprod Toxicol 2018; 78:60-68. [PMID: 29581082 DOI: 10.1016/j.reprotox.2018.03.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 03/01/2018] [Accepted: 03/22/2018] [Indexed: 12/19/2022]
Abstract
Methylmercury, a potent neurotoxin, is able to pass through the placenta, but its effects on the placenta itself have not been elucidated. Using an immortalized human trophoblast cell line, HTR8/SV-neo, we assessed the in vitro toxicity of methylmercury. We found that 1 μg/mL methylmercury decreased viability, proliferation, and migration; and it had effects on antioxidant genes similar to those seen in neural cells. However, methylmercury led to decreased expression of superoxide dismutase 1 and increased expression of surfactant protein D. HTR cells treated 0.01 or 0.1 μg/mL methylmercury had increased migration rates along with decreased expression of an adhesion gene, cadherin 3, suggesting that low doses of methylmercury promote migration in HTR cells. Our results indicate that trophoblast cells react differently to methylmercury relative to neural cell lines, and thus investigation of methylmercury toxicity in placental cells is needed to understand the effects of this heavy metal on the placenta.
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Affiliation(s)
- Emily K Tucker
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, 1207, W. Gregory Dr., Urbana, Illinois, USA.
| | - Romana A Nowak
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, 1207, W. Gregory Dr., Urbana, Illinois, USA
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Prince LM, Rand MD. Methylmercury exposure causes a persistent inhibition of myogenin expression and C2C12 myoblast differentiation. Toxicology 2018; 393:113-122. [PMID: 29104120 PMCID: PMC5757876 DOI: 10.1016/j.tox.2017.11.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 10/03/2017] [Accepted: 11/01/2017] [Indexed: 12/11/2022]
Abstract
Methylmercury (MeHg) is a ubiquitous environmental toxicant, best known for its selective targeting of the developing nervous system. MeHg exposure has been shown to cause motor deficits such as impaired gait and coordination, muscle weakness, and muscle atrophy, which have been associated with disruption of motor neurons. However, recent studies have suggested that muscle may also be a target of MeHg toxicity, both in the context of developmental myogenic events and of low-level chronic exposures affecting muscle wasting in aging. We therefore investigated the effects of MeHg on myotube formation, using the C2C12 mouse myoblast model. We found that MeHg inhibits both differentiation and fusion, in a concentration-dependent manner. Furthermore, MeHg specifically and persistently inhibits myogenin (MyoG), a transcription factor involved in myocyte differentiation, within the first six hours of exposure. MeHg-induced reduction in MyoG expression is contemporaneous with a reduction of a number of factors involved in mitochondrial biogenesis and mtDNA transcription and translation, which may implicate a role for mitochondria in mediating MeHg-induced change in the differentiation program. Unexpectedly, inhibition of myoblast differentiation with MeHg parallels inhibition of Notch receptor signaling. Our research establishes muscle cell differentiation as a target for MeHg toxicity, which may contribute to the underlying etiology of motor deficits with MeHg toxicity.
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Affiliation(s)
- Lisa M Prince
- University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Department of Environmental Medicine, Rochester, NY, 14642, USA.
| | - Matthew D Rand
- University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Department of Environmental Medicine, Rochester, NY, 14642, USA.
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26
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Hernández AJA, Reyes VL, Albores-García D, Gómez R, Calderón-Aranda ES. MeHg affects the activation of FAK, Src, Rac1 and Cdc42, critical proteins for cell movement in PDGF-stimulated SH-SY5Y neuroblastoma cells. Toxicology 2017; 394:35-44. [PMID: 29197552 DOI: 10.1016/j.tox.2017.11.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 10/16/2017] [Accepted: 11/28/2017] [Indexed: 01/05/2023]
Abstract
Methylmercury (MeHg) is an environmental neurotoxicant that inhibits neuronal migration. This process requires several cyclic steps involving the formation of membrane protrusions (lamellipodia and filopodia) and focal adhesion turnover. FAK and Src are critical proteins that regulate both processes. The FAK-Src complex promotes the activation of Rac1 and Cdc42, two GTPases involved in the remodeling of the actin cytoskeletal network. Here, we studied the effect of MeHg (1, 10, 100, 500 and 1000nM) on cell migration, the formation of cell protrusions, focal adhesion location and the activation of FAK, Src, Rac1 and Cdc42 using the SH-SY5Y neuroblastoma cell line stimulated with PDGF-BB (PDGF). The data show that MeHg (1-500nM) inhibited PDGF-stimulated cell migration. In PDGF-stimulated cells, MeHg (100-1000nM) decreased protrusions and increased the size of the p-FAKY397 clusters. MeHg also inhibited PDGF-induced FAK and Src activation and, at 100nM, MeHg inhibited the activation of Rac1 and Cdc42. Altogether, the findings show that low concentrations of MeHg inhibit SH-SY5Y cell migration by disrupting the activation and disassembly of FAK. This negatively affects the activation of Src, Rac1 and Cdc42, all of which are critical proteins for the regulation of cell movement. These effects could be related to the MeHg-mediated inhibition of PDGF-induced formation of lamellipodia and filopodia, focal adhesion disassembly and PDGF-induced movement.
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Affiliation(s)
| | | | | | - Rocío Gómez
- Departamento de Toxicologia, Cinvestav, DF. Mexico, Mexico
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Hofrichter M, Nimtz L, Tigges J, Kabiri Y, Schröter F, Royer-Pokora B, Hildebrandt B, Schmuck M, Epanchintsev A, Theiss S, Adjaye J, Egly JM, Krutmann J, Fritsche E. Comparative performance analysis of human iPSC-derived and primary neural progenitor cells (NPC) grown as neurospheres in vitro. Stem Cell Res 2017; 25:72-82. [PMID: 29112887 DOI: 10.1016/j.scr.2017.10.013] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 10/17/2017] [Accepted: 10/23/2017] [Indexed: 02/07/2023] Open
Abstract
Developmental neurotoxicity (DNT) testing performed in rats is resource-intensive (costs, time, animals) and bears the issue of species extrapolation. Thus, reliable alternative human-based approaches are needed for predicting neurodevelopmental toxicity. Human induced pluripotent stem cells (hiPSCs) represent a basis for an alternative method possibly being part of an alternative DNT testing strategy. Here, we compared two hiPSC neural induction protocols resulting in 3D neurospheres: one using noggin and one cultivating cells in neural induction medium (NIM protocol). Performance of Nestin+/SOX2+ hiPSC-derived neural progenitor cells (NPCs) was compared to primary human NPCs. Generally, primary hNPCs first differentiate into Nestin+ and/or GFAP+ radial glia-like cells, while the hiPSC-derived NPCs (hiPSC-NPC) first differentiate into βIII-Tubulin+ neurons suggesting an earlier developmental stage of hiPSC-NPC. In the 'Neurosphere Assay', NIM generated hiPSC-NPC produced neurons with higher performance than with the noggin protocol. After long-term differentiation, hiPSC-NPC form neuronal networks, which become electrically active on microelectrode arrays after 85days. Finally, methylmercury chloride inhibits hiPSC-NPC and hNPC migration with similar potencies. hiPSC-NPCs-derived neurospheres seem to be useful for DNT evaluation representing early neural development in vitro. More system characterization by compound testing is needed to gain higher confidence in this method.
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Affiliation(s)
- Maxi Hofrichter
- IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Laura Nimtz
- IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Julia Tigges
- IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Yaschar Kabiri
- IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Friederike Schröter
- Institute for Stem Cell Research & Regenerative Medicine, Medical Faculty, Heinrich-Heine-University, Duesseldorf, Germany
| | - Brigitte Royer-Pokora
- Institute of Human Genetics, Medical Faculty, Heinrich-Heine University, Duesseldorf, Germany
| | - Barbara Hildebrandt
- Institute of Human Genetics, Medical Faculty, Heinrich-Heine University, Duesseldorf, Germany
| | - Martin Schmuck
- IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Alexey Epanchintsev
- Department of Functional Genomics and Cancer, Institut de Génétique et de Biologie Moléculaire et Cellulaire: IGBMC, Centre National de la Recherche Scientifique, INSERUM, Université de Strasbourg, Strasbourg, France
| | - Stephan Theiss
- Institute of clinical neuroscience and medical psychology, Medical Faculty, Heinrich-Heine-University, Duesseldorf, Germany
| | - James Adjaye
- Institute for Stem Cell Research & Regenerative Medicine, Medical Faculty, Heinrich-Heine-University, Duesseldorf, Germany
| | - Jean-Marc Egly
- Department of Functional Genomics and Cancer, Institut de Génétique et de Biologie Moléculaire et Cellulaire: IGBMC, Centre National de la Recherche Scientifique, INSERUM, Université de Strasbourg, Strasbourg, France
| | - Jean Krutmann
- IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany; Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Ellen Fritsche
- IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany; Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany.
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Developmental neurotoxicity of the hippocampus following in utero exposure to methylmercury: impairment in cell signaling. Arch Toxicol 2017; 92:513-527. [PMID: 28821999 DOI: 10.1007/s00204-017-2042-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 08/10/2017] [Indexed: 01/01/2023]
Abstract
In this study, we assessed some hippocampal signaling cascades and behavioral impairments in 30-day-old rat pups prenatally exposed to methylmercury (MeHg). Pregnant rats were exposed to 1.0 or 2.0 mg/kg MeHg by gavage in alternated days from gestational day 5 until parturition. We found increased anxiety-like and decreased exploration behavior evaluated by open field test and deficit of both short- and long-term memories by novel object recognition task, respectively, in MeHg-treated pups. Downregulated PI3K/Akt/mTOR pathway and activated/hypophosphorylated (Ser9) GSK3β in MeHg-treated pups could be upstream of hyperphosphorylated Tau (Ser396) destabilizing microtubules and contributing to neural dysfunction in the hippocampus of these rats. Hyperphosphorylated/activated p38MAPK and downregulated phosphoErk1/2 support a role for mitogen-activated protein kinase (MAPK) cascade on MeHg neurotoxicity. Decreased receptor of advanced glycation end products (RAGE) immunocontent supports the assumption that downregulated RAGE/Erk1/2 pathway could be involved in hypophosphorylated lysine/serine/proline (KSP) repeats on neurofilament subunits and disturbed axonal transport. Downregulated myelin basic protein (MBP), the major myelin protein, is compatible with dysmyelination and neurofilament hypophosphorylation. Increased glial fibrillary acidic protein (GFAP) levels suggest reactive astrocytes, and active apoptotic pathways BAD/BCL-2, BAX/BCL-XL, and caspase 3 suggest cell death. Taken together, our findings get light on important signaling mechanisms that could underlie the behavioral deficits in 30-day-old pups prenatally exposed to MeHg.
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Kalia V, Perera F, Tang D. Environmental Pollutants and Neurodevelopment: Review of Benefits From Closure of a Coal-Burning Power Plant in Tongliang, China. Glob Pediatr Health 2017; 4:2333794X17721609. [PMID: 28812058 PMCID: PMC5542072 DOI: 10.1177/2333794x17721609] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 06/13/2017] [Accepted: 06/21/2017] [Indexed: 12/02/2022] Open
Abstract
Background. Understanding preventable causes of neurodevelopmental disorders is a public health priority. Polycyclic aromatic hydrocarbons (PAH) from combustion of fossil fuel, lead, and mercury are among known neurodevelopmental toxicants. Method. For the first time, we comprehensively review the findings from a study by the Columbia Center for Children's Environmental Health and Chinese partners that followed 2 groups of mother-child pairs, one from 2002 and another from 2005, in Tongliang County, China. Pregnant mothers in the 2 cohorts experienced different exposure to PAH because a local coal-burning power plant was shut down in 2004. Investigators assessed change in prenatal PAH exposure, measured using a biomarker (benzo[a]pyrene [BaP]-DNA adducts in cord blood). Developmental quotients were measured using the Gesell Developmental Scales at age 2 and IQ was assessed using the Wechsler Intelligence Scale for Children at age 5. Biologic markers of preclinical response were measured in cord blood: methylation status of long interspersed nuclear elements (LINE1), an indicator of genomic stability, and brain-derived neurotrophic factor (BDNF), a neuronal growth promoter. Analyses accounted for co-exposure to lead and mercury. Results. BaP-DNA adducts were significantly inversely associated with Gesell Developmental Scales scores in the first cohort but not in the second cohort; and levels of BDNF and LINE1 methylation were higher in the second cohort. Conclusion. In this study, reduced exposure to PAH was associated with beneficial effects on neurodevelopment as well as molecular changes related to improved brain development and health. These benefits should encourage further efforts to limit exposure to these toxic pollutants.
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Affiliation(s)
- Vrinda Kalia
- Department of Environmental Health Sciences, Columbia Center for Children’s Environemental Health, Mailman School of Public Health, Columbia University, New York, NY, USA
| | - Frederica Perera
- Department of Environmental Health Sciences, Columbia Center for Children’s Environemental Health, Mailman School of Public Health, Columbia University, New York, NY, USA
| | - Deliang Tang
- Department of Environmental Health Sciences, Columbia Center for Children’s Environemental Health, Mailman School of Public Health, Columbia University, New York, NY, USA
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Edoff K, Raciti M, Moors M, Sundström E, Ceccatelli S. Gestational Age and Sex Influence the Susceptibility of Human Neural Progenitor Cells to Low Levels of MeHg. Neurotox Res 2017; 32:683-693. [PMID: 28756503 PMCID: PMC5602033 DOI: 10.1007/s12640-017-9786-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 07/09/2017] [Accepted: 07/12/2017] [Indexed: 01/13/2023]
Abstract
The developing nervous system is highly susceptible to methylmercury (MeHg), a widespread environmental neurotoxic contaminant. A wide range of morphological and functional outcomes have been described; however, there are still open questions regarding the mechanisms behind the developmental neurotoxic effects induced by low-level exposure. In the present study, we have examined the effects of nanomolar concentrations of MeHg on primary fetal human progenitor cells (hNPCs) with special focus on the role played by developmental stage and sex on the neurotoxic outcome. We found that neurospheres derived from earlier gestational time points exhibit higher susceptibility to MeHg, as they undergo apoptosis at a much lower dose (25 nM) as compared to neurospheres established from older fetuses (100 nM). At subapoptotic concentrations (10 nM), MeHg inhibited neuronal differentiation and maturation of hNPCs, as shown by a reduced number of Tuj1-positive cells and a visible reduction in neurite extension and cell migration, associated with a misregulation of Notch1 and BDNF signaling pathways. Interestingly, cells derived from male fetuses showed more severe alterations of neuronal morphology as compared to cells from females, indicating that the MeHg-induced impairment of neurite extension and cell migration is sex-dependent. Accordingly, the expression of the CDKL5 gene, a major factor regulating neurite outgrowth, was significantly more downregulated in male-derived cells. Altogether, gestational age and sex appear to be critical factors influencing in vitro hNPC sensitivity to low levels of MeHg.
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Affiliation(s)
- Karin Edoff
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, SE-171 77, Stockholm, Sweden
| | - Marilena Raciti
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, SE-171 77, Stockholm, Sweden.
| | - Michaela Moors
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, SE-171 77, Stockholm, Sweden
| | - Erik Sundström
- Department of Neurobiology, Care Sciences, and Society, Karolinska Institutet, Geriatrik-lab plan 5, SE-141 52, Huddinge, Sweden
| | - Sandra Ceccatelli
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, SE-171 77, Stockholm, Sweden
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Jacob S, Thangarajan S. Effect of Gestational Intake of Fisetin (3,3',4',7-Tetrahydroxyflavone) on Developmental Methyl Mercury Neurotoxicity in F 1 Generation Rats. Biol Trace Elem Res 2017; 177:297-315. [PMID: 27815688 DOI: 10.1007/s12011-016-0886-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 10/24/2016] [Indexed: 12/16/2022]
Abstract
Methyl mercury (MeHg) is a developmental neurotoxin that causes irreversible cognitive damage in offspring of gestationally exposed mothers. Currently, no preventive drugs are established against MeHg developmental neurotoxicity. The neuroprotective effect of gestational administration of a flavanoid against in utero toxicity of MeHg is not explored much. Hence, the present study validated the effect of a bioactive flavanoid, fisetin, on MeHg developmental neurotoxicity outcomes in rat offspring at postnatal weaning age. Pregnant Wistar rats were simultaneously given MeHg (1.5 mg/kg b.w.) and two doses of fisetin (10 and 50 mg/kg b.w. in two separate groups) orally from gestational day (GD) 5 till parturition. Accordingly, after parturition, on postnatal day (PND) 24, weaning F1 generation rats were studied for motor and cognitive behavioural changes. Biochemical and histopathological changes were also studied in the cerebral cortex, cerebellum and hippocampus on PND 25. Administration of fisetin during pregnancy prevented behavioural impairment due to transplacental MeHg exposure in weaning rats. Fisetin decreased the levels of oxidative stress markers, increased enzymatic and non-enzymatic antioxidant levels and increased the activity of membrane-bound ATPases and cholinergic function in F1 generation rats. In light microscopic studies, fisetin treatment protected the specific offspring brain regions from significant morphological aberrations. Between the two doses of fisetin studied, 10 mg/kg b.w. was found to be more satisfactory and effective than 50 mg/kg b.w. The present study shows that intake of fisetin during pregnancy in rats ameliorated in utero MeHg exposure-induced neurotoxicity outcomes in postnatal weaning F1 generation rats.
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Affiliation(s)
- Sherin Jacob
- Department of Medical Biochemistry, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, Tamil Nadu, 600 113, India
| | - Sumathi Thangarajan
- Department of Medical Biochemistry, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, Tamil Nadu, 600 113, India.
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Alves AC, Monteiro MS, Machado AL, Oliveira M, Bóia A, Correia A, Oliveira N, Soares AMVM, Loureiro S. Mercury levels in parturient and newborns from Aveiro region, Portugal. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2017; 80:697-709. [PMID: 28524771 DOI: 10.1080/15287394.2017.1286926] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Since the outbreak of methylmercury (MeHg) poisoning in Japan and Iraq, mercury (Hg) is classified as well-established teratogen. The Portuguese region of Aveiro faced some decades ago an environmental Hg contamination due to activities from a chlor-alkali plant. Until now, no apparent evaluation was conducted regarding prenatal exposure to Hg in this area. The main objectives of this study were to: i) assess maternal and fetal exposure to Hg in the Aveiro region using noninvasive biological matrices; ii) examine the influence of variables that may contribute to Hg exposure during pregnancy; and iii) improve knowledge regarding metal accumulation and distribution over the maternal-fetal-placental unit. This study was performed in 50 mother-newborn pairs from the Aveiro district. Total Hg (THg) was quantified in maternal scalp hair, placenta, amniotic membrane, and umbilical cord. Maternal hair presented THg levels with a mean value of 900 ng/g, which is lower than the USEPA and WHO acceptable threshold. Regarding THg levels in placenta and umbilical cord, mean values were similar (decidua basalis: 32.84 ng/g; chorionic plate: 30.18 ng/g; umbilical cord: 30.67 ng/g). The amniotic membrane presented the highest THg levels with a mean concentration of 42.35 ng/g, reaching a maximum of 134.1 ng/g. Further, a significant positive correlation was noted between THg levels found in hair, and all matrices analyzed reinforcing the use of hair in biomonitoring studies with respect to maternal exposure to Hg. In general, levels of THg found in our study were lower than those in previous studies performed in Europe. Consumption of fish rich in selenium and bottled water was negatively correlated with THg levels. Finally, data demonstrated that Hg is capable of crossing the placental barrier and accumulate in placental tissues. Amniotic membrane seemed to play a role in metal detoxification, but further investigations are necessary to examine whether this catabolic process affects Hg accumulation.
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Affiliation(s)
- Ana Catarina Alves
- a Department of Biology & Centro de Estudos do Ambiente e do MAR (CESAM) , University of Aveiro , Aveiro , Portugal
| | - Marta S Monteiro
- a Department of Biology & Centro de Estudos do Ambiente e do MAR (CESAM) , University of Aveiro , Aveiro , Portugal
| | - Ana Luísa Machado
- a Department of Biology & Centro de Estudos do Ambiente e do MAR (CESAM) , University of Aveiro , Aveiro , Portugal
| | - Mário Oliveira
- b Obstetrics and Gynecology Department, Infante D.Pedro Hospital , Centro Hospitalar Baixo , Vouga , EPE, Aveiro , Portugal
| | - Ana Bóia
- b Obstetrics and Gynecology Department, Infante D.Pedro Hospital , Centro Hospitalar Baixo , Vouga , EPE, Aveiro , Portugal
| | - Ana Correia
- b Obstetrics and Gynecology Department, Infante D.Pedro Hospital , Centro Hospitalar Baixo , Vouga , EPE, Aveiro , Portugal
| | - Nuno Oliveira
- b Obstetrics and Gynecology Department, Infante D.Pedro Hospital , Centro Hospitalar Baixo , Vouga , EPE, Aveiro , Portugal
| | - Amadeu M V M Soares
- a Department of Biology & Centro de Estudos do Ambiente e do MAR (CESAM) , University of Aveiro , Aveiro , Portugal
| | - Susana Loureiro
- a Department of Biology & Centro de Estudos do Ambiente e do MAR (CESAM) , University of Aveiro , Aveiro , Portugal
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Swaddle JP, Diehl TR, Taylor CE, Fanaee AS, Benson JL, Huckstep NR, Cristol DA. Exposure to dietary mercury alters cognition and behavior of zebra finches. Curr Zool 2017; 63:213-219. [PMID: 29491979 PMCID: PMC5804164 DOI: 10.1093/cz/zox007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 02/03/2017] [Indexed: 11/15/2022] Open
Abstract
Environmental stressors can negatively affect avian cognitive abilities, potentially reducing fitness, for example by altering response to predators, display to mates, or memory of locations of food. We expand on current knowledge by investigating the effects of dietary mercury, a ubiquitous environmental pollutant and known neurotoxin, on avian cognition. Zebra finches Taeniopygia guttata were dosed for their entire lives with sub-lethal levels of mercury, at the environmentally relevant dose of 1.2 parts per million. In our first study, we compared the dosed birds with controls of the same age using tests of three cognitive abilities: spatial memory, inhibitory control, and color association. In the spatial memory assay, birds were tested on their ability to learn and remember the location of hidden food in their cage. The inhibitory control assay measured their ability to ignore visible but inaccessible food in favor of a learned behavior that provided the same reward. Finally, the color association task tested each bird's ability to associate a specific color with the presence of hidden food. Dietary mercury negatively affected spatial memory ability but not inhibitory control or color association. Our second study focused on three behavioral assays not tied to a specific skill or problem-solving: activity level, neophobia, and social dominance. Zebra finches exposed to dietary mercury throughout their lives were subordinate to, and more active than, control birds. We found no evidence that mercury exposure influenced our metric of neophobia. Together, these results suggest that sub-lethal exposure to environmental mercury selectively harms neurological pathways that control different cognitive abilities, with complex effects on behavior and fitness.
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Affiliation(s)
- John P Swaddle
- Biology Department, College of William and Mary, Institute for Integrative Bird Behavior Studies, Williamsburg, VA 23187-8795, USA
| | - Tessa R Diehl
- Biology Department, College of William and Mary, Institute for Integrative Bird Behavior Studies, Williamsburg, VA 23187-8795, USA
| | - Capwell E Taylor
- Biology Department, College of William and Mary, Institute for Integrative Bird Behavior Studies, Williamsburg, VA 23187-8795, USA
| | - Aaron S Fanaee
- Biology Department, College of William and Mary, Institute for Integrative Bird Behavior Studies, Williamsburg, VA 23187-8795, USA
| | - Jessica L Benson
- Biology Department, College of William and Mary, Institute for Integrative Bird Behavior Studies, Williamsburg, VA 23187-8795, USA
| | - Neil R Huckstep
- Biological Sciences, Virginia Tech, 1405 Perry Street, Blacksburg, VA 24061, USA
| | - Daniel A Cristol
- Biology Department, College of William and Mary, Institute for Integrative Bird Behavior Studies, Williamsburg, VA 23187-8795, USA
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Yoshida S, Matsumoto S, Kanchika T, Hagiwara T, Minami T. The organic mercury compounds, methylmercury and ethylmercury, inhibited ciliary movement of ventricular ependymal cells in the mouse brain around the concentrations reported for human poisoning. Neurotoxicology 2016; 57:69-74. [DOI: 10.1016/j.neuro.2016.08.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 08/15/2016] [Indexed: 11/29/2022]
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Antunes Dos Santos A, Appel Hort M, Culbreth M, López-Granero C, Farina M, Rocha JBT, Aschner M. Methylmercury and brain development: A review of recent literature. J Trace Elem Med Biol 2016; 38:99-107. [PMID: 26987277 PMCID: PMC5011031 DOI: 10.1016/j.jtemb.2016.03.001] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 03/02/2016] [Indexed: 02/02/2023]
Abstract
Methylmercury (MeHg) is a potent environmental pollutant, which elicits significant toxicity in humans. The central nervous system (CNS) is the primary target of toxicity, and is particularly vulnerable during development. Maternal exposure to MeHg via consumption of fish and seafood can have irreversible effects on the neurobehavioral development of children, even in the absence of symptoms in the mother. It is well documented that developmental MeHg exposure may lead to neurological alterations, including cognitive and motor dysfunction. The neurotoxic effects of MeHg on the developing brain have been extensively studied. The mechanism of toxicity, however, is not fully understood. No single process can explain the multitude of effects observed in MeHg-induced neurotoxicity. This review summarizes the most current knowledge on the effects of MeHg during nervous system development considering both, in vitro and in vivo experimental models. Considerable attention was directed towards the role of glutamate and calcium dyshomeostasis, mitochondrial dysfunction, as well as the effects of MeHg on cytoskeletal components/regulators.
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Affiliation(s)
| | - Mariana Appel Hort
- Institute of Biological Sciences, Federal University of Rio Grande, Campus Carreiros, Rio Grande do Sul, Brazil
| | - Megan Culbreth
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Caridad López-Granero
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Marcelo Farina
- Department of Biochemistry, Federal University of Santa Catarina, Florianopolis, Santa Catarina, Brazil
| | - Joao B T Rocha
- Department of Biochemistry, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA.
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Pregnant Women in Louisiana Are Not Meeting Dietary Seafood Recommendations. J Pregnancy 2016; 2016:1853935. [PMID: 27504202 PMCID: PMC4967672 DOI: 10.1155/2016/1853935] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 05/18/2016] [Accepted: 06/22/2016] [Indexed: 11/17/2022] Open
Abstract
Background. The 2015-2020 Dietary Guidelines for Americans recommend that pregnant women and women of childbearing ages consume 8-12 oz. of seafood per week. Fish are the major dietary source of omega-3 long chain polyunsaturated fatty acids, which have benefits for the mother and fetus. Methods. In this observational study, we investigated dietary habits of pregnant women in Baton Rouge, Louisiana, USA, to determine if they achieve recommended seafood intake. A print survey, which included commonly consumed foods from protein sources (beef, chicken, pork, and fish), was completed by pregnant women at a single-day hospital convention for expecting families in October 2015. Women (n = 221) chose from six predefined responses to answer how frequently they were consuming each food. Results. Chicken was consumed most frequently (75% of women), followed by beef (71%), pork (65%), and fish (22%), respectively. Consumption frequency for the most consumed fish (catfish, once per month) was similar to or lower than that of the least consumed beef, chicken, and pork foods. Consumption frequency for the most consumed chicken and beef foods was at least once per week. Conclusion. Our data indicate that pregnant women in Louisiana often consume protein sources other than fish and likely fail to meet dietary seafood recommendations.
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Ratcliffe HE, Swanson GM, Fischer LJ. Human Exposure to Mercury: A Critical Assessment of the Evidence of Adverse Health Effects. ACTA ACUST UNITED AC 2015. [DOI: 10.1080/00984108.1996.11667600] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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MeHg Developing Exposure Causes DNA Double-Strand Breaks and Elicits Cell Cycle Arrest in Spinal Cord Cells. J Toxicol 2015; 2015:532691. [PMID: 26793240 PMCID: PMC4697092 DOI: 10.1155/2015/532691] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 11/22/2015] [Accepted: 11/23/2015] [Indexed: 12/11/2022] Open
Abstract
The neurotoxicity caused by methylmercury (MeHg) is well documented; however, the developmental neurotoxicity in spinal cord is still not fully understood. Here we investigated whether MeHg affects the spinal cord layers development. Chicken embryos at E3 were treated in ovo with 0.1 μg MeHg/50 μL saline solution and analyzed at E10. Thus, we performed immunostaining using anti-γ-H2A.X to recognize DNA double-strand breaks and antiphosphohistone H3, anti-p21, and anti-cyclin E to identify cells in proliferation and cell cycle proteins. Also, to identify neuronal cells, we used anti-NeuN and anti-βIII-tubulin antibodies. After the MeHg treatment, we observed the increase on γ-H2A.X in response to DNA damage. MeHg caused a decrease in the proliferating cells and in the thickness of spinal cord layers. Moreover, we verified that MeHg induced an increase in the number of p21-positive cells but did not change the cyclin E-positive cells. A significantly high number of TUNEL-positive cells indicating DNA fragmentation were observed in MeHg-treated embryos. Regarding the neuronal differentiation, MeHg induced a decrease in NeuN expression and did not change the expression of βIII-tubulin. These results showed that in ovo MeHg exposure alters spinal cord development by disturbing the cell proliferation and death, also interfering in early neuronal differentiation.
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Trentini JF, O'Neill JT, Poluch S, Juliano SL. Prenatal carbon monoxide impairs migration of interneurons into the cerebral cortex. Neurotoxicology 2015; 53:31-44. [PMID: 26582457 DOI: 10.1016/j.neuro.2015.11.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 11/09/2015] [Accepted: 11/09/2015] [Indexed: 01/15/2023]
Abstract
Prenatal exposure to carbon monoxide (CO) disrupts brain development, however little is known about effects on neocortical maturation. We exposed pregnant mice to CO from embryonic day 7 (E7) until birth. To study the effect of CO on neuronal migration into the neocortex we injected BrdU during corticogenesis and observed misplaced BrdU+ cells. The majority of cells not in their proper layer colocalized with GAD65/67, suggesting impairment of interneuron migration; interneuron subtypes were also affected. We subsequently followed interneuron migration from E15 organotypic cultures of mouse neocortex exposed to CO; the leading process length of migrating neurons diminished. To examine an underlying mechanism, we assessed the effects of CO on the cellular cascade mediating the cytoskeletal protein vasodilator-stimulated phosphoprotein (VASP). CO exposure resulted in decreased cGMP and in a downstream target, phosphorylated VASP. Organotypic cultures grown in the presence of the phosphodiesterase inhibitor IBMX resulted in a recovery of the leading processes. These data support the idea that CO acts as a signaling molecule and impairs function and neuronal migration by acting through the CO/NO-cGMP pathway. In addition, treated mice demonstrated functional impairment in behavioral tests.
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Affiliation(s)
- John F Trentini
- Graduate Program in Neuroscience, Uniformed Services University, Bethesda, MD 20814, USA
| | - J Timothy O'Neill
- Graduate Program in Neuroscience, Uniformed Services University, Bethesda, MD 20814, USA; Department of Pediatrics, Uniformed Services University, Bethesda, MD 20814, USA
| | - Sylvie Poluch
- Graduate Program in Neuroscience, Uniformed Services University, Bethesda, MD 20814, USA; Department of Anatomy, Physiology and Genetics, Uniformed Services University, Bethesda, MD 20814, USA
| | - Sharon L Juliano
- Graduate Program in Neuroscience, Uniformed Services University, Bethesda, MD 20814, USA; Department of Anatomy, Physiology and Genetics, Uniformed Services University, Bethesda, MD 20814, USA.
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McKean SJ, Bartell SM, Hansen RL, Barfod GH, Green PG, Hertz-Picciotto I. Prenatal mercury exposure, autism, and developmental delay, using pharmacokinetic combination of newborn blood concentrations and questionnaire data: a case control study. Environ Health 2015; 14:62. [PMID: 26198445 PMCID: PMC4508765 DOI: 10.1186/s12940-015-0045-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 06/08/2015] [Indexed: 05/28/2023]
Abstract
BACKGROUND Methylmercury (MeHg), known for well over a century as a neurotoxin in adults, has more recently been studied for potential detrimental effects during early brain development. While several studies have estimated mercury exposure, they usually rely on either a single biomarker or questionnaire data, each of which has limitations. The goal of this paper was to develop a toxicokinetic model that incorporates both biomarker and questionnaire data to estimate the cumulative exposure to MeHg through seafood consumption using data collected from the Childhood Autism Risks from Genetics and the Environment (CHARGE) study. METHODS We utilized a previously described discrete-time model that estimates blood MeHg concentration given a piecewise-constant ingestion rate and single-compartment pharmacokinetics. We measured newborn bloodspot Hg concentrations and obtained information pertaining to maternal fish consumption using a questionnaire. Using MeHg concentration estimates from the toxicokinetic model, cumulative MeHg exposure was estimated in children with autism, children with developmental delay, and typically developing children. Median estimated cumulative MeHg was compared among diagnostic groups using the Kruskal-Wallis Test. Multinomial logistic regression models were constructed to assess the association between cumulative MeHg concentration and the risk of autism and developmental delay (vs. typical development). RESULTS The estimated average MeHg concentration of for all fish species consumed by mothers was 42 ppb. Median cumulative MeHg over gestation was similar across diagnostic groups (p-values raged from 0.91 to 0.98). After adjusting for potential confounding, we found no association between cumulative MeHg exposure and the risk of autism (OR = 0.95, 95% CI: 0.95, 1.12) or developmental delay (OR = 1.00, 95% CI: 0.89, 1.13). CONCLUSIONS The toxicokinetic model described in this paper yielded fish MeHg concentration estimates that are consistent with fish species containing lower levels of MeHg. Overall, cumulative MeHg exposure does not appear to detectably elevate the risk of autism or developmental delay. Based on the regression standard error for the association between ASD and TD, we would have reported statistical significance for an adjusted odds ratio of 1.09 or larger. This method can easily be extended to other epidemiologic studies in which there is a biomarker measurement and questionnaire data regarding exposure.
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Affiliation(s)
| | - Scott M Bartell
- Program in Public Health and Department of Statistics, University of California, Irvine, Irvine, CA, USA.
| | - Robin L Hansen
- Department of Pediatrics, University of California, Davis, Sacramento, CA, USA.
- MIND Institute, School of Medicine, University of California, Davis, Sacramento, CA, USA.
| | - Gry H Barfod
- Interdisciplinary Center for Plasma Mass Spectrometry, University of California, Davis, Davis, CA, 95616, USA.
| | - Peter G Green
- Department of Civil and Environmental Engineering, University of California, Davis, Davis, CA, USA.
| | - Irva Hertz-Picciotto
- MIND Institute, School of Medicine, University of California, Davis, Sacramento, CA, USA.
- Department of Public Health Sciences, University of California, Davis, Davis, CA, USA.
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Obiorah M, McCandlish E, Buckley B, DiCicco-Bloom E. Hippocampal developmental vulnerability to methylmercury extends into prepubescence. Front Neurosci 2015; 9:150. [PMID: 26029035 PMCID: PMC4429234 DOI: 10.3389/fnins.2015.00150] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Accepted: 04/14/2015] [Indexed: 12/27/2022] Open
Abstract
The developing brain is sensitive to environmental toxicants such as methylmercury (MeHg), to which humans are exposed via contaminated seafood. Prenatal exposure in children is associated with learning, memory and IQ deficits, which can result from hippocampal dysfunction. To explore underlying mechanisms, we have used the postnatal day (P7) rat to model the third trimester of human gestation. We previously showed that a single low exposure (0.6 μg/gbw) that approaches human exposure reduced hippocampal neurogenesis in the dentate gyrus (DG) 24 h later, producing later proliferation and memory deficits in adolescence. Yet, the vulnerable stem cell population and period of developmental vulnerability remain undefined. In this study, we find that P7 exposure of stem cells has long-term consequences for adolescent neurogenesis. It reduced the number of mitotic S-phase cells (BrdU), especially those in the highly proliferative Tbr2+ population, and immature neurons (Doublecortin) in adolescence, suggesting partial depletion of the later stem cell pool. To define developmental vulnerability to MeHg in prepubescent (P14) and adolescent (P21) rats, we examined acute 24 h effects of MeHg exposure on mitosis and apoptosis. We found that low exposure did not adversely impact neurogenesis at either age, but that a higher exposure (5 μg/gbw) at P14 reduced the total number of neural stem cells (Sox2+) by 23% and BrdU+ cells by 26% in the DG hilus, suggesting that vulnerability diminishes with age. To determine whether these effects reflect changes in MeHg transfer across the blood brain barrier (BBB), we assessed Hg content in the hippocampus after peripheral injection and found that similar levels (~800 ng/gm) were obtained at 24 h at both P14 and P21, declining in parallel, suggesting that changes in vulnerability depend more on local tissue and cellular mechanisms. Together, we show that MeHg vulnerability declines with age, and that early exposure impairs later neurogenesis in older juveniles.
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Affiliation(s)
- Maryann Obiorah
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Rutgers The State University of New Jersey Piscataway, NJ, USA
| | - Elizabeth McCandlish
- Environmental and Occupational Health Sciences Institute, Rutgers The State University of New Jersey Piscataway, NJ, USA
| | - Brian Buckley
- Environmental and Occupational Health Sciences Institute, Rutgers The State University of New Jersey Piscataway, NJ, USA
| | - Emanuel DiCicco-Bloom
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Rutgers The State University of New Jersey Piscataway, NJ, USA ; Department of Pediatrics, Rutgers Robert Wood Johnson Medical School, Rutgers The State University of New Jersey New Brunswick, NJ, USA
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Yuntao F, Chenjia G, Panpan Z, Wenjun Z, Suhua W, Guangwei X, Haifeng S, Jian L, Wanxin P, Yun F, Cai J, Aschner M, Rongzhu L. Role of autophagy in methylmercury-induced neurotoxicity in rat primary astrocytes. Arch Toxicol 2014; 90:333-45. [PMID: 25488884 DOI: 10.1007/s00204-014-1425-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 11/25/2014] [Indexed: 11/30/2022]
Abstract
Autophagy is an evolutionarily conserved process in which cytoplasmic proteins and organelles are degraded and recycled for reuse. There are numerous reports on the role of autophagy in cell growth and death; however, the role of autophagy in methylmercury (MeHg)-induced neurotoxicity has yet to be identified. We studied the role of autophagy in MeHg-induced neurotoxicity in astrocytes. MeHg reduced astrocytic viability in a concentration- and time-dependent manner, and induced apoptosis. Pharmacological inhibition of autophagy with 3-methyladenine or chloroquine, as well as the silencing of the autophagy-related protein 5, increased MeHg-induced cytotoxicity and the ratio of apoptotic astrocytes. Conversely, rapamycin, an autophagy inducer, along with as N-acetyl-L-cysteine, a precursor of reduced glutathione, decreased MeHg-induced toxicity and the ratio of apoptotic astrocytes. These results indicated that MeHg-induced neurotoxicity was reduced, at least in part, through the activation of autophagy. Accordingly, modulation of autophagy may offer a new avenue for attenuating MeHg-induced neurotoxicity.
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Affiliation(s)
- Fang Yuntao
- Department of Public Health Laboratory Sciences, School of Medicine, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Guo Chenjia
- Department of Public Health Laboratory Sciences, School of Medicine, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Zhang Panpan
- Department of Public Health Laboratory Sciences, School of Medicine, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Zhao Wenjun
- Department of Public Health Laboratory Sciences, School of Medicine, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Wang Suhua
- Department of Public Health Laboratory Sciences, School of Medicine, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Xing Guangwei
- Department of Public Health Laboratory Sciences, School of Medicine, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Shi Haifeng
- Institute of Life Sciences, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Lu Jian
- Department of Public Health Laboratory Sciences, School of Medicine, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Peng Wanxin
- Department of Biology, School of Medicine, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Feng Yun
- Department of Pharmacology, School of Medicine, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Jiyang Cai
- Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch, Galveston, TX, 77550-1106, USA
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Lu Rongzhu
- Department of Public Health Laboratory Sciences, School of Medicine, Jiangsu University, Zhenjiang, 212013, Jiangsu, China.
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Lamm SH, Li J, Robbins SA, Dissen E, Chen R, Feinleib M. Are residents of mountain-top mining counties more likely to have infants with birth defects? The West Virginia experience. ACTA ACUST UNITED AC 2014; 103:76-84. [PMID: 25388330 DOI: 10.1002/bdra.23322] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND Pooled 1996 to 2003 birth certificate data for four central states in Appalachia indicated higher rates of infants with birth defects born to residents of counties with mountain-top mining (MTM) than born to residents of non-mining-counties (Ahern 2011). However, those analyses did not consider sources of uncertainty such as unbalanced distributions or quality of data. Quality issues have been a continuing problem with birth certificate analyses. We used 1990 to 2009 live birth certificate data for West Virginia to reassess this hypothesis. METHODS Forty-four hospitals contributed 98% of the MTM-county births and 95% of the non-mining-county births, of which six had more than 1000 births from both MTM and nonmining counties. Adjusted and stratified prevalence rate ratios (PRRs) were computed both by using Poisson regression and Mantel-Haenszel analysis. RESULTS Unbalanced distribution of hospital births was observed by mining groups. The prevalence rate of infants with reported birth defects, higher in MTM-counties (0.021) than in non-mining-counties (0.015), yielded a significant crude PRR (cPRR = 1.43; 95% confidence interval [CI] = 1.36-1.52) but a nonsignificant hospital-adjusted PRR (adjPRR = 1.08; 95% CI = 0.97-1.20; p = 0.16) for the 44 hospitals. So did the six hospital data analysis ([cPRR = 2.39; 95% CI = 2.15-2.65] and [adjPRR = 1.01; 95% CI, 0.89-1.14; p = 0.87]). CONCLUSION No increased risk of birth defects was observed for births from MTM-counties after adjustment for, or stratification by, hospital of birth. These results have consistently demonstrated that the reported association between birth defect rates and MTM coal mining was a consequence of data heterogeneity. The data do not demonstrate evidence of a "Mountain-top Mining" effect on the prevalence of infants with reported birth defects in WV.
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Affiliation(s)
- Steven H Lamm
- Consultants in Epidemiology and Occupational Health (CEOH), LLC, Washington, District of Columbia, USA; Department of Health Policy and Management, Johns Hopkins University- Bloomberg School of Public Health, Baltimore, Maryland, USA; Department of Pediatrics, Georgetown University School of Medicine, Washington, District of Columbia, USA
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Montgomery SL, Vorojeikina D, Huang W, Mackay TFC, Anholt RRH, Rand MD. Genome-wide association analysis of tolerance to methylmercury toxicity in Drosophila implicates myogenic and neuromuscular developmental pathways. PLoS One 2014; 9:e110375. [PMID: 25360876 PMCID: PMC4215868 DOI: 10.1371/journal.pone.0110375] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 09/11/2014] [Indexed: 11/30/2022] Open
Abstract
Methylmercury (MeHg) is a persistent environmental toxin present in seafood that can compromise the developing nervous system in humans. The effects of MeHg toxicity varies among individuals, despite similar levels of exposure, indicating that genetic differences contribute to MeHg susceptibility. To examine how genetic variation impacts MeHg tolerance, we assessed developmental tolerance to MeHg using the sequenced, inbred lines of the Drosophila melanogaster Genetic Reference Panel (DGRP). We found significant genetic variation in the effects of MeHg on development, measured by eclosion rate, giving a broad sense heritability of 0.86. To investigate the influence of dietary factors, we measured MeHg toxicity with caffeine supplementation in the DGRP lines. We found that caffeine counteracts the deleterious effects of MeHg in the majority of lines, and there is significant genetic variance in the magnitude of this effect, with a broad sense heritability of 0.80. We performed genome-wide association (GWA) analysis for both traits, and identified candidate genes that fall into several gene ontology categories, with enrichment for genes involved in muscle and neuromuscular development. Overexpression of glutamate-cysteine ligase, a MeHg protective enzyme, in a muscle-specific manner leads to a robust rescue of eclosion of flies reared on MeHg food. Conversely, mutations in kirre, a pivotal myogenic gene identified in our GWA analyses, modulate tolerance to MeHg during development in accordance with kirre expression levels. Finally, we observe disruptions of indirect flight muscle morphogenesis in MeHg-exposed pupae. Since the pathways for muscle development are evolutionarily conserved, it is likely that the effects of MeHg observed in Drosophila can be generalized across phyla, implicating muscle as an additional hitherto unrecognized target for MeHg toxicity. Furthermore, our observations that caffeine can ameliorate the toxic effects of MeHg show that nutritional factors and dietary manipulations may offer protection against the deleterious effects of MeHg exposure.
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Affiliation(s)
- Sara L. Montgomery
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Daria Vorojeikina
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Wen Huang
- Department of Biological Sciences, Genetics Program, and W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Trudy F. C. Mackay
- Department of Biological Sciences, Genetics Program, and W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Robert R. H. Anholt
- Department of Biological Sciences, Genetics Program, and W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Matthew D. Rand
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
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Marine diet and tobacco exposure affects mercury concentrations in pregnant women (I) from Baja California Sur, Mexico. Toxicol Rep 2014; 1:1123-1132. [PMID: 28203532 PMCID: PMC5304913 DOI: 10.1016/j.toxrep.2014.10.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Seafood provides essential polyunsaturated fatty acids (PUFA) and other nutrients to pregnant women and their fetus(es) while a diet rich in finfish can be a major pathway of monomethyl mercury (MeHg+) exposure. We measured total mercury concentration ([THg]) in hair samples provided by 75 women in Baja California Sur (BCS) to assess its relationship with age, parity, tobacco smoke exposure, and diet based on survey methodologies. Generalized linear models (GLM) were used to explain the possible association of the different variables with [THg] in hair. Median [THg] in hair was 1.52 µgg-1, ranging from 0.12 to 24.19 µgg-1 and varied significantly by segment. Approximately 72% (54/75) of those evaluated exceed 1 µgg-1 [THg] and 8% (6/75) exceed 5 µgg-1 [THg] in hair. Although frequency of fish consumption contributed significantly to explaining hair [THg], fish consumption only explained 43% of [THg] in a GLM incorporating tobacco exposure and body mass index. This study establishes possible relationships among multiple potential sources of exposure and other factors related to [THg] in hair of women in the prenatal period. A more detailed examination of other sources of exposure and factors contributing to [THg] is warranted.
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Chang SH, Lee HJ, Kang B, Yu KN, Minai-Tehrani A, Lee S, Kim SU, Cho MH. Methylmercury induces caspase-dependent apoptosis and autophagy in human neural stem cells. J Toxicol Sci 2014; 38:823-31. [PMID: 24213001 DOI: 10.2131/jts.38.823] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Methylmercury (MeHg) is a well-known human neurotoxic agent whose exposure sources are mainly environmental and aquatic-derived food. MeHg is reported to induce central nervous system disability. However, the exact mechanism of MeHg-induced neurotoxicity is still unknown. In this study, to investigate which cell death signaling pathway is related with MeHg-induced cytotoxicity, the effects of MeHg on apoptosis and autophagy were evaluated in HB1.F3 human neural stem cells (NSCs). Human NSCs were treated with 1 μM of MeHg for 48 hr and the effect of MeHg on cell signaling pathway was elucidated. MeHg inhibited Akt1/mTOR signaling that led to induction of caspase-dependent apoptosis and autophagy in the NSCs. Furthermore, retinoic acid (RA)-induced neuronal differentiation was inhibited by MeHg. Taken together, these results suggest that MeHg inhibits the differentiation of human NSCs by induction of caspase-dependent apoptosis and autophagy.
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Affiliation(s)
- Seung-Hee Chang
- Laboratory of Toxicology, College of Veterinary Medicine, Seoul National University, Korea
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Komuro Y, Galas L, Lebon A, Raoult E, Fahrion JK, Tilot A, Kumada T, Ohno N, Vaudry D, Komuro H. The role of calcium and cyclic nucleotide signaling in cerebellar granule cell migration under normal and pathological conditions. Dev Neurobiol 2014; 75:369-87. [PMID: 25066767 DOI: 10.1002/dneu.22219] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 06/30/2014] [Accepted: 07/25/2014] [Indexed: 11/07/2022]
Abstract
In the developing brain, immature neurons migrate from their sites of origin to their final destination, where they reside for the rest of their lives. This active movement of immature neurons is essential for the formation of normal neuronal cytoarchitecture and proper differentiation. Deficits in migration result in the abnormal development of the brain, leading to a variety of neurological disorders. A myriad of extracellular guidance molecules and intracellular effector molecules is involved in controlling the migration of immature neurons in a cell type, cortical layer and birth-date-specific manner. To date, little is known about how extracellular guidance molecules transfer their information to the intracellular effector molecules, which regulate the migration of immature neurons. In this article, to fill the gap between extracellular guidance molecules and intracellular effector molecules, using the migration of cerebellar granule cells as a model system of neuronal cell migration, we explore the role of second messenger signaling (specifically Ca(2+) and cyclic nucleotide signaling) in the regulation of neuronal cell migration. We will, first, describe the cortical layer-specific changes in granule cell migration. Second, we will discuss the roles of Ca(2+) and cyclic nucleotide signaling in controlling granule cell migration. Third, we will present recent studies showing the roles of Ca(2+) and cyclic nucleotide signaling in the deficits in granule cell migration in mouse models of fetal alcohol spectrum disorders and fetal Minamata disease.
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Affiliation(s)
- Yutaro Komuro
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio, 44195
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Bisen-Hersh EB, Farina M, Barbosa F, Rocha JBT, Aschner M. Behavioral effects of developmental methylmercury drinking water exposure in rodents. J Trace Elem Med Biol 2014; 28:117-124. [PMID: 24210169 PMCID: PMC3979511 DOI: 10.1016/j.jtemb.2013.09.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 09/19/2013] [Accepted: 09/19/2013] [Indexed: 10/26/2022]
Abstract
Early methylmercury (MeHg) exposure can have long-lasting consequences likely arising from impaired developmental processes, the outcome of which has been exposed in several longitudinal studies of affected populations. Given the large number of newborns at an increased risk of learning disabilities associated with in utero MeHg exposure, it is important to study neurobehavioral alterations using ecologically valid and physiologically relevant models. This review highlights the benefits of using the MeHg drinking water exposure paradigm and outlines behavioral outcomes arising from this procedure in rodents. Combination treatments that exacerbate or ameliorate MeHg-induced effects, and possible molecular mechanisms underlying behavioral impairment are also discussed.
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Affiliation(s)
- Emily B Bisen-Hersh
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Marcelo Farina
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Fernando Barbosa
- Department of Clinical, Toxicological and Bromatological Analyses, Faculty of Pharmaceutical Sciences of Ribeirão Preto, São Paulo, Brazil
| | - Joao B T Rocha
- Departamento de Química, Universidade Federal de Santa Maria, Santa Maria, Rio Grande do Sul, Brazil
| | - Michael Aschner
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Pharmacology, The Kennedy Center for Research on Human Development, and The Center for Molecular Toxicology, Vanderbilt University Medical Center, Nashville, TN, USA
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