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Pamphlett R, Bishop DP. The toxic metal hypothesis for neurological disorders. Front Neurol 2023; 14:1173779. [PMID: 37426441 PMCID: PMC10328356 DOI: 10.3389/fneur.2023.1173779] [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: 02/25/2023] [Accepted: 05/30/2023] [Indexed: 07/11/2023] Open
Abstract
Multiple sclerosis and the major sporadic neurogenerative disorders, amyotrophic lateral sclerosis, Parkinson disease, and Alzheimer disease are considered to have both genetic and environmental components. Advances have been made in finding genetic predispositions to these disorders, but it has been difficult to pin down environmental agents that trigger them. Environmental toxic metals have been implicated in neurological disorders, since human exposure to toxic metals is common from anthropogenic and natural sources, and toxic metals have damaging properties that are suspected to underlie many of these disorders. Questions remain, however, as to how toxic metals enter the nervous system, if one or combinations of metals are sufficient to precipitate disease, and how toxic metal exposure results in different patterns of neuronal and white matter loss. The hypothesis presented here is that damage to selective locus ceruleus neurons from toxic metals causes dysfunction of the blood-brain barrier. This allows circulating toxicants to enter astrocytes, from where they are transferred to, and damage, oligodendrocytes, and neurons. The type of neurological disorder that arises depends on (i) which locus ceruleus neurons are damaged, (ii) genetic variants that give rise to susceptibility to toxic metal uptake, cytotoxicity, or clearance, (iii) the age, frequency, and duration of toxicant exposure, and (iv) the uptake of various mixtures of toxic metals. Evidence supporting this hypothesis is presented, concentrating on studies that have examined the distribution of toxic metals in the human nervous system. Clinicopathological features shared between neurological disorders are listed that can be linked to toxic metals. Details are provided on how the hypothesis applies to multiple sclerosis and the major neurodegenerative disorders. Further avenues to explore the toxic metal hypothesis for neurological disorders are suggested. In conclusion, environmental toxic metals may play a part in several common neurological disorders. While further evidence to support this hypothesis is needed, to protect the nervous system it would be prudent to take steps to reduce environmental toxic metal pollution from industrial, mining, and manufacturing sources, and from the burning of fossil fuels.
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Affiliation(s)
- Roger Pamphlett
- Department of Pathology, Brain and Mind Centre, School of Medical Sciences, The University of Sydney, Sydney, NSW, Australia
- Department of Neuropathology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
- Hyphenated Mass Spectrometry Laboratory, School of Mathematical and Physical Sciences, University of Technology Sydney, Sydney, NSW, Australia
| | - David P. Bishop
- Hyphenated Mass Spectrometry Laboratory, School of Mathematical and Physical Sciences, University of Technology Sydney, Sydney, NSW, Australia
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Azevedo LF, Karpova N, Rocha BA, Barbosa Junior F, Gobe GC, Hornos Carneiro MF. Evidence on Neurotoxicity after Intrauterine and Childhood Exposure to Organomercurials. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:1070. [PMID: 36673825 PMCID: PMC9858833 DOI: 10.3390/ijerph20021070] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/03/2023] [Accepted: 01/04/2023] [Indexed: 06/17/2023]
Abstract
Although the molecular mechanisms underlying methylmercury toxicity are not entirely understood, the observed neurotoxicity in early-life is attributed to the covalent binding of methylmercury to sulfhydryl (thiol) groups of proteins and other molecules being able to affect protein post-translational modifications from numerous molecular pathways, such as glutamate signaling, heat-shock chaperones and the antioxidant glutaredoxin/glutathione system. However, for other organomercurials such as ethylmercury or thimerosal, there is not much information available. Therefore, this review critically discusses current knowledge about organomercurials neurotoxicity-both methylmercury and ethylmercury-following intrauterine and childhood exposure, as well as the prospects and future needs for research in this area. Contrasting with the amount of epidemiological evidence available for methylmercury, there are only a few in vivo studies reporting neurotoxic outcomes and mechanisms of toxicity for ethylmercury or thimerosal. There is also a lack of studies on mechanistic approaches to better investigate the pathways involved in the potential neurotoxicity caused by both organomercurials. More impactful follow-up studies, especially following intrauterine and childhood exposure to ethylmercury, are necessary. Childhood vaccination is critically important for controlling infectious diseases; however, the safety of mercury-containing thimerosal and, notably, its effectiveness as preservative in vaccines are still under debate regarding its potential dose-response effects to the central nervous system.
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Affiliation(s)
- Lara Ferreira Azevedo
- Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040-903, SP, Brazil
| | - Nina Karpova
- Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040-903, SP, Brazil
| | - Bruno Alves Rocha
- Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040-903, SP, Brazil
| | - Fernando Barbosa Junior
- Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040-903, SP, Brazil
| | - Glenda Carolyn Gobe
- Kidney Disease Research Group, School of Medicine, Translational Research Institute, University of Queensland, 37 Kent Street, Woolloongabba, QLD 4102, Australia
| | - Maria Fernanda Hornos Carneiro
- Department of Pharmacy, Faculty of Chemistry and Pharmacy, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
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Saucier D, Registe PPW, Bélanger M, O'Connell C. Urbanization, air pollution, and water pollution: Identification of potential environmental risk factors associated with amyotrophic lateral sclerosis using systematic reviews. Front Neurol 2023; 14:1108383. [PMID: 36970522 PMCID: PMC10030603 DOI: 10.3389/fneur.2023.1108383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Accepted: 02/13/2023] [Indexed: 03/29/2023] Open
Abstract
Introduction Despite decades of research, causes of ALS remain unclear. To evaluate recent hypotheses of plausible environmental factors, the aim of this study was to synthesize and appraise literature on the potential associations between the surrounding environment, including urbanization, air pollution and water pollution, and ALS. Methods We conducted a series (n = 3) of systematic reviews in PubMed and Scopus to identify epidemiological studies assessing relationships between urbanization, air pollution and water pollution with the development of ALS. Results The combined search strategy led to the inclusion of 44 articles pertaining to at least one exposure of interest. Of the 25 included urbanization studies, four of nine studies on living in rural areas and three of seven studies on living in more highly urbanized/dense areas found positive associations to ALS. There were also three of five studies for exposure to electromagnetic fields and/or proximity to powerlines that found positive associations to ALS. Three case-control studies for each of diesel exhaust and nitrogen dioxide found positive associations with the development of ALS, with the latter showing a dose-response in one study. Three studies for each of high selenium content in drinking water and proximity to lakes prone to cyanobacterial blooms also found positive associations to ALS. Conclusion Whereas markers of air and water pollution appear as potential risk factors for ALS, results are mixed for the role of urbanization.
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Affiliation(s)
- Daniel Saucier
- Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
- Center de formation médicale du Nouveau-Brunswick, Moncton, NB, Canada
- *Correspondence: Daniel Saucier
| | - Pierre Philippe Wilson Registe
- Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
- Center de formation médicale du Nouveau-Brunswick, Moncton, NB, Canada
| | - Mathieu Bélanger
- Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
- Center de formation médicale du Nouveau-Brunswick, Moncton, NB, Canada
| | - Colleen O'Connell
- Stan Cassidy Center for Rehabilitation, Fredericton, NB, Canada
- Department of Medicine, Dalhousie Medicine New Brunswick, Saint John, NB, Canada
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Peters S, Broberg K, Gallo V, Levi M, Kippler M, Vineis P, Veldink J, van den Berg L, Middleton L, Travis RC, Bergmann MM, Palli D, Grioni S, Tumino R, Elbaz A, Vlaar T, Mancini F, Kühn T, Katzke V, Agudo A, Goñi F, Gómez J, Rodríguez‐Barranco M, Merino S, Barricarte A, Trichopoulou A, Jenab M, Weiderpass E, Vermeulen R. Blood Metal Levels and Amyotrophic Lateral Sclerosis Risk: A Prospective Cohort. Ann Neurol 2021; 89:125-133. [PMID: 33068316 PMCID: PMC7756568 DOI: 10.1002/ana.25932] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 10/14/2020] [Accepted: 10/14/2020] [Indexed: 01/12/2023]
Abstract
OBJECTIVE Metals have been suggested as a risk factor for amyotrophic lateral sclerosis (ALS), but only retrospective studies are available to date. We compared metal levels in prospectively collected blood samples from ALS patients and controls, to explore whether metals are associated with ALS mortality. METHODS A nested ALS case-control study was conducted within the prospective EPIC (European Prospective Investigation into Cancer and Nutrition) cohort. Cases were identified through death certificates. We analyzed metal levels in erythrocyte samples obtained at recruitment, as a biomarker for metal exposure from any source. Arsenic, cadmium, copper, lead, manganese, mercury, selenium, and zinc concentrations were measured by inductively coupled plasma-mass spectrometry. To estimate ALS risk, we applied conditional logistic regression models. RESULTS The study population comprised 107 cases (65% female) and 319 controls matched for age, sex, and study center. Median time between blood collection and ALS death was 8 years (range = 1-15). Comparing the highest with the lowest tertile, cadmium (odds ratio [OR] = 2.04, 95% confidence interval [CI] = 1.08-3.87) and lead (OR = 1.89, 95% CI = 0.97-3.67) concentrations suggest associations with increased ALS risk. Zinc was associated with a decreased risk (OR = 0.50, 95% CI = 0.27-0.94). Associations for cadmium and lead remained when limiting analyses to noncurrent smokers. INTERPRETATION This is the first study to compare metal levels before disease onset, minimizing reverse causation. The observed associations suggest that cadmium, lead, and zinc may play a role in ALS etiology. Cadmium and lead possibly act as intermediates on the pathway from smoking to ALS. ANN NEUROL 20209999:n/a-n/a.
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Affiliation(s)
- Susan Peters
- Institute for Risk Assessment SciencesUtrecht UniversityUtrechtthe Netherlands
- Department of NeurologyUniversity Medical Center UtrechtUtrechtthe Netherlands
| | - Karin Broberg
- Institute of Environmental MedicineKarolinska InstituteSolnaSweden
| | - Valentina Gallo
- Centre for Primary Care and Public HealthQueen Mary University of LondonLondonUK
| | - Michael Levi
- Institute of Environmental MedicineKarolinska InstituteSolnaSweden
| | - Maria Kippler
- Institute of Environmental MedicineKarolinska InstituteSolnaSweden
| | - Paolo Vineis
- School of Public HealthImperial College LondonLondonUK
| | - Jan Veldink
- Department of NeurologyUniversity Medical Center UtrechtUtrechtthe Netherlands
| | | | | | - Ruth C. Travis
- Cancer Epidemiology UnitNuffield Department of Population Health, University of OxfordOxfordUK
| | | | - Domenico Palli
- Cancer Risk Factors and Life‐Style Epidemiology UnitInstitute for Cancer Research, Prevention and Clinical NetworkFlorenceItaly
| | - Sara Grioni
- Epidemiology and Prevention UnitIRCCS National Cancer Institute FoundationMilanItaly
| | - Rosario Tumino
- Cancer Registry and Histopathology DepartmentProvincial Health CompanyRagusaItaly
| | - Alexis Elbaz
- Public Health FranceSaint‐MauriceFrance
- Paris‐Sud UniversityUVSQ, CESP, INSERM, Paris‐Saclay UniversityVillejuifFrance
| | - Tim Vlaar
- Public Health FranceSaint‐MauriceFrance
- Paris‐Sud UniversityUVSQ, CESP, INSERM, Paris‐Saclay UniversityVillejuifFrance
| | - Francesca Mancini
- Faculty of Medicine, CESP, Paris‐Sud University, UVSQ, INSERMParis‐Saclay UniversityVillejuifFrance
- Gustave Roussy InstituteVillejuifFrance
| | - Tilman Kühn
- German Cancer Research CenterHeidelbergGermany
| | | | - Antonio Agudo
- Unit of Nutrition and Cancer, Cancer Epidemiology Research Program, Catalan Institute of Oncology, Group of Research on Nutrition and CancerBellvitge Biomedical Research Institute, L'Hospitalet de LlobregatBarcelonaSpain
| | - Fernando Goñi
- Networked Biomedical Research Center of Epidemiology and Public HealthMadridSpain
- Biodonostia Health Research Institute; Public Health Laboratory in GipuzkoaBasque GovernmentSan SebastianSpain
| | - Jesús‐Humberto Gómez
- Networked Biomedical Research Center of Epidemiology and Public HealthMadridSpain
- Department of EpidemiologyRegional Health Council, IMIB‐ArrixacaMurciaSpain
| | - Miguel Rodríguez‐Barranco
- Networked Biomedical Research Center of Epidemiology and Public HealthMadridSpain
- Andalusian School of Public HealthGranadaSpain
- Grenada Institute of Biosanitary ResearchGranadaSpain
| | | | - Aurelio Barricarte
- Networked Biomedical Research Center of Epidemiology and Public HealthMadridSpain
- Navarra Public Health InstitutePamplonaSpain
- Navarra Institute for Health ResearchPamplonaSpain
| | | | - Mazda Jenab
- International Agency for Research on CancerLyonFrance
| | | | - Roel Vermeulen
- Institute for Risk Assessment SciencesUtrecht UniversityUtrechtthe Netherlands
- School of Public HealthImperial College LondonLondonUK
- Julius Center for Health Sciences and Primary CareUniversity Medical Center UtrechtUtrechtthe Netherlands
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Kelberman M, Keilholz S, Weinshenker D. What's That (Blue) Spot on my MRI? Multimodal Neuroimaging of the Locus Coeruleus in Neurodegenerative Disease. Front Neurosci 2020; 14:583421. [PMID: 33122996 PMCID: PMC7573566 DOI: 10.3389/fnins.2020.583421] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 09/16/2020] [Indexed: 01/04/2023] Open
Abstract
The locus coeruleus (LC) has long been underappreciated for its role in the pathophysiology of Alzheimer’s disease (AD), Parkinson’s disease (PD), and other neurodegenerative disorders. While AD and PD are distinct in clinical presentation, both are characterized by prodromal protein aggregation in the LC, late-stage degeneration of the LC, and comorbid conditions indicative of LC dysfunction. Many of these early studies were limited to post-mortem histological techniques due to the LC’s small size and location deep in the brainstem. Thus, there is a growing interest in utilizing in vivo imaging of the LC as a predictor of preclinical neurodegenerative processes and biomarker of disease progression. Simultaneously, neuroimaging in animal models of neurodegenerative disease holds promise for identifying early alterations to LC circuits, but has thus far been underutilized. While still in its infancy, a handful of studies have reported effects of single gene mutations and pathology on LC function in disease using various neuroimaging techniques. Furthermore, combining imaging and optogenetics or chemogenetics allows for interrogation of network connectivity in response to changes in LC activity. The purpose of this article is twofold: (1) to review what magnetic resonance imaging (MRI) and positron emission tomography (PET) have revealed about LC dysfunction in neurodegenerative disease and its potential as a biomarker in humans, and (2) to explore how animal models can be used to test hypotheses derived from clinical data and establish a mechanistic framework to inform LC-focused therapeutic interventions to alleviate symptoms and impede disease progression.
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Affiliation(s)
- Michael Kelberman
- Department of Human Genetics, Emory University, Atlanta, GA, United States
| | - Shella Keilholz
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Emory University, Atlanta, GA, United States
| | - David Weinshenker
- Department of Human Genetics, Emory University, Atlanta, GA, United States
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6
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Bismuth as Smart Material and Its Application in the Ninth Principle of Sustainable Chemistry. J CHEM-NY 2020. [DOI: 10.1155/2020/9802934] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
This paper reports an overview of Green Chemistry and the concept of its twelve principles. This study focusses on the ninth principle of Green Chemistry, that is, catalysis. A report on catalysis, in line with its definition, background, classification, properties, and applications, is provided. The study also entails a green element called bismuth. Bismuth’s low toxicity and low cost have made researchers focus on its wide applications in catalysis. It exhibits smartness in all the catalytic activities with the highest catalytic performance among other metals.
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Pamphlett R, Mak R, Lee J, Buckland ME, Harding AJ, Kum Jew S, Paterson DJ, Jones MWM, Lay PA. Concentrations of toxic metals and essential trace elements vary among individual neurons in the human locus ceruleus. PLoS One 2020; 15:e0233300. [PMID: 32428015 PMCID: PMC7237016 DOI: 10.1371/journal.pone.0233300] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 05/02/2020] [Indexed: 12/17/2022] Open
Abstract
Objective Damage to locus ceruleus neurons could play a part in the pathogenesis of neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease, and multiple sclerosis because of impairment of the blood-brain barrier and enhanced neuroinflammation. The locus ceruleus has connections throughout the brain and spinal cord, so the characteristic widespread multifocal pathology in these disorders could be due to damage to different subsets of locus ceruleus neurons. Previous studies have shown that only certain locus ceruleus neurons accumulate the neurotoxic metal mercury. To find out if concentrations of other toxic metals or of essential trace elements also vary between individual locus ceruleus neurons, we used synchrotron X-ray fluorescence microscopy on frozen sections of locus ceruleus neurons taken from people with multiple sclerosis, in whom the locus ceruleus is structurally intact. Materials and methods Paraffin embedded sections containing the locus ceruleus from seven people with multiple sclerosis were stained with autometallography that demonstrates accumulations of mercury, silver and bismuth. These were compared to maps of multiple elements obtained from frozen sections of locus ceruleus neurons from the same people using X-ray fluorescence microscopy. Neurons in the anterior pons from three of these donors were used as internal controls. Results Autometallography staining was observed in scattered locus ceruleus neurons from three of the seven donors. X-ray fluorescence microscopy showed variations among individual locus ceruleus neurons in levels of mercury, selenium, iron, copper, lead, bromine, and rubidium. Variations between donors of locus ceruleus neuronal average levels of mercury, iron, copper, and bromine were also detected. Anterior pons neurons contained no mercury, had varied levels of iron, and had lower copper levels than locus ceruleus neurons. Conclusions Individual human locus ceruleus neurons contain varying levels of toxic metals and essential trace elements. In contrast, most toxic metals are absent or at low levels in nearby anterior pons neurons. The locus ceruleus plays a role in numerous central nervous system functions, including maintaining the blood-brain-barrier and limiting neuroinflammation. Toxic metals, or alterations in essential trace metals within individual locus ceruleus neurons, could be one factor determining the non-random destruction of locus ceruleus neurons in normal aging and neurodegenerative diseases, and subsequently the sites of the widespread multifocal central nervous system pathology in these disorders.
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Affiliation(s)
- Roger Pamphlett
- Discipline of Pathology, Sydney Medical School, Brain and Mind Centre, The University of Sydney, Sydney, New South Wales, Australia
- Department of Neuropathology, Royal Prince Alfred Hospital, Brain and Mind Centre, Sydney, New South Wales, Australia
- * E-mail:
| | - Rachel Mak
- School of Chemistry and Sydney Analytical, The University of Sydney, Sydney, New South Wales, Australia
| | - Joonsup Lee
- School of Chemistry and Sydney Analytical, The University of Sydney, Sydney, New South Wales, Australia
| | - Michael E. Buckland
- Discipline of Pathology, Sydney Medical School, Brain and Mind Centre, The University of Sydney, Sydney, New South Wales, Australia
- Department of Neuropathology, Royal Prince Alfred Hospital, Brain and Mind Centre, Sydney, New South Wales, Australia
| | - Antony J. Harding
- Department of Neuropathology, Royal Prince Alfred Hospital, Brain and Mind Centre, Sydney, New South Wales, Australia
| | - Stephen Kum Jew
- Discipline of Pathology, Sydney Medical School, Brain and Mind Centre, The University of Sydney, Sydney, New South Wales, Australia
| | | | | | - Peter A. Lay
- School of Chemistry and Sydney Analytical, The University of Sydney, Sydney, New South Wales, Australia
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Andrew AS, O’Brien KM, Jackson BP, Sandler DP, Kaye WE, Wagner L, Stommel EW, Horton DK, Mehta P, Weinberg CR. Keratinous biomarker of mercury exposure associated with amyotrophic lateral sclerosis risk in a nationwide U.S. study. Amyotroph Lateral Scler Frontotemporal Degener 2020; 21:420-427. [DOI: 10.1080/21678421.2020.1753777] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
| | - Katie M. O’Brien
- National Institute of Environmental Health Sciences, Durham, NC, USA,
| | - Brian P. Jackson
- Department of Earth Sciences, Dartmouth College, Hanover, NH, USA,
| | - Dale P. Sandler
- National Institute of Environmental Health Sciences, Durham, NC, USA,
| | | | | | | | - D. Kevin Horton
- Centers for Disease Control and Prevention (CDC), Agency for Toxic Substances and Disease Registry (ATSDR), Atlanta, GA, USA
| | - Paul Mehta
- Centers for Disease Control and Prevention (CDC), Agency for Toxic Substances and Disease Registry (ATSDR), Atlanta, GA, USA
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9
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Santana LNDS, Bittencourt LO, Nascimento PC, Fernandes RM, Teixeira FB, Fernandes LMP, Freitas Silva MC, Nogueira LS, Amado LL, Crespo-Lopez ME, Maia CDSF, Lima RR. Low doses of methylmercury exposure during adulthood in rats display oxidative stress, neurodegeneration in the motor cortex and lead to impairment of motor skills. J Trace Elem Med Biol 2019; 51:19-27. [PMID: 30466930 DOI: 10.1016/j.jtemb.2018.09.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 08/21/2018] [Accepted: 09/10/2018] [Indexed: 12/20/2022]
Abstract
Despite the vast distribution among tissues, the central nervous system (CNS) represents the main target of methylmercury (MeHg) toxicity. However, few studies have evaluated the effects of MeHg exposure on the CNS at equivalent doses to human environmental exposure. In our study, we evaluated the motor cortex, an important area of motor control, in adult rats chronically exposed to MeHg in a concentration equivalent to those found in fish-eating populations exposed to mercury (Hg). The parameters evaluated were total Hg accumulation, oxidative stress, tissue damage, and behavioral assessment in functional actions that involved this cortical region. Our results show in exposed animals a significantly greater level of Hg in the motor cortex; increase of nitrite levels and lipid peroxidation, associated with decreased antioxidant capacity against peroxyl radicals; reduction of neuronal and astrocyte density; and poor coordination and motor learning impairment. Our data showed that chronic exposure at low doses to MeHg is capable of promoting damages to the motor cortex of adult animals, with changes in oxidative biochemistry misbalance, neurodegeneration, and motor function impairment.
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Affiliation(s)
- Luana Nazaré da Silva Santana
- 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
| | - Priscila Cunha Nascimento
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, PA, Brazil
| | - Rafael Monteiro Fernandes
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, PA, Brazil
| | - Francisco Bruno Teixeira
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, PA, Brazil
| | - Luanna Melo Pereira Fernandes
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, PA, Brazil
| | - Marcia Cristina Freitas Silva
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, PA, Brazil
| | - Lygia Sega Nogueira
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, PA, Brazil
| | - Lílian Lund Amado
- Laboratory of Ecotoxicology, Institute of Biological Sciences, Federal University of Pará, Belém, PA, Brazil
| | - Maria Elena Crespo-Lopez
- Laboratory of Molecular Pharmacology, Institute of Biological Sciences, Federal University of Pará, Belém, PA, Brazil
| | - Cristiane do Socorro Ferraz Maia
- Laboratory of Pharmacology of Inflammation and Behavior, Institute of Health Sciences, Federal University of Pará, Belém, PA, Brazil
| | - Rafael Rodrigues Lima
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, PA, Brazil.
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A Comparison of Mercury Exposure from Seafood Consumption and Dental Amalgam Fillings in People with and without Amyotrophic Lateral Sclerosis (ALS): An International Online Case-Control Study. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2018; 15:ijerph15122874. [PMID: 30558238 PMCID: PMC6313312 DOI: 10.3390/ijerph15122874] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 12/07/2018] [Accepted: 12/11/2018] [Indexed: 12/12/2022]
Abstract
Exposures to toxic metals such as mercury have been suggested to be risk factors for amyotrophic lateral sclerosis (ALS). Human intake of mercury commonly occurs via consumption of seafood or from mercury-containing amalgam dental restorations ('mercury fillings'). We therefore compared mercury exposures from these sources in 401 ALS and 452 non-ALS respondents, using an internationally-available online questionnaire that asked respondents how often they ate seafood and what their favourite types of seafoods were. Respondents were also asked to record numbers of current or former mercury fillings. ALS and non-ALS respondents did not differ in their frequency of seafood consumption or in monthly mercury intake from favourite seafoods. Both groups had similar numbers of current, as well as former, mercury fillings. In conclusion, this study found no evidence that mercury exposure from eating seafood, or from mercury dental fillings, was associated with the risk of developing ALS. Therefore, if mercury does play a role in the pathogenesis of ALS, other sources of exposure to mercury in the environment or workplace need to be considered. Alternatively, a susceptibility to mercury toxicity in ALS, such as genetic or epigenetic variations, multiple toxic metal interactions, or selenium deficiency, may be present.
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11
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Pamphlett R, Bishop DP, Kum Jew S, Doble PA. Age-related accumulation of toxic metals in the human locus ceruleus. PLoS One 2018; 13:e0203627. [PMID: 30231068 PMCID: PMC6145836 DOI: 10.1371/journal.pone.0203627] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 08/23/2018] [Indexed: 12/28/2022] Open
Abstract
Damage to the locus ceruleus has been implicated in the pathogenesis of a number of neurological conditions. Locus ceruleus neurons accumulate toxic metals such as mercury selectively, however, the presence of toxic metals in locus ceruleus neurons of people of different ages, and with a variety of disorders, is not known. To demonstrate at what age toxic metals are first detectable in the locus ceruleus, and to evaluate whether their presence is more common in certain clinicopathological conditions, we looked for these metals in 228 locus ceruleus samples. Samples were taken at coronial autopsies from individuals with a wide range of ages, pre-existing conditions and causes of death. Paraffin sections of pons containing the locus ceruleus were stained with silver nitrate autometallography, which indicates inorganic mercury, silver and bismuth within cells (termed autometallography-detected toxic metals, or AMG™). No locus ceruleus AMG neurons were seen in 38 individuals aged under 20 years. 47% of the 190 adults (ie, aged 20 years and over) had AMG locus ceruleus neurons. The proportion of adults with locus ceruleus AMG neurons increased during aging, except for a decreased proportion in the 90-plus years age group. No differences were found in the proportions of locus ceruleus AMG neurons between groups with different neurological, psychiatric, or other clinicopathological conditions, or among various causes of death. Elemental analysis with laser ablation-inductively coupled plasma-mass spectrometry was used to cross-validate the metals detected by AMG, by looking for silver, gold, bismuth, cadmium, chromium, iron, mercury, nickel, and lead in the locus ceruleus of ten individuals. This confirmed the presence of mercury in locus ceruleus samples containing AMG neurons, and showed cadmium, silver, lead, iron, and nickel in the locus ceruleus of some individuals. In conclusion, toxic metals stained by AMG (most likely inorganic mercury) appear in locus ceruleus neurons in early adult life. About half of adults in this study had locus ceruleus neurons containing inorganic mercury, and elemental analysis found a range of other toxic metals in the locus ceruleus. Locus ceruleus inorganic mercury increased during aging, except for a decrease in advanced age, but was not found more often in any single clinicopathological condition or cause of death.
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Affiliation(s)
- Roger Pamphlett
- Discipline of Pathology, Sydney Medical School, Brain and Mind Centre, The University of Sydney, New South Wales, Australia
- Department of Neuropathology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
| | - David P. Bishop
- Elemental Bio-imaging Facility, University of Technology, Sydney, New South Wales, Australia
| | - Stephen Kum Jew
- Discipline of Pathology, Sydney Medical School, Brain and Mind Centre, The University of Sydney, New South Wales, Australia
| | - Philip A. Doble
- Elemental Bio-imaging Facility, University of Technology, Sydney, New South Wales, Australia
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Oliveira CS, Nogara PA, Ardisson-Araújo DMP, Aschner M, Rocha JBT, Dórea JG. Neurodevelopmental Effects of Mercury. ADVANCES IN NEUROTOXICOLOGY 2018; 2:27-86. [PMID: 32346667 PMCID: PMC7188190 DOI: 10.1016/bs.ant.2018.03.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The toxicology of mercury (Hg) is of concern since this metal is ubiquitously distributed in the environment, and living organisms are routinely exposed to Hg at low to high levels. The toxic effects of Hg are well studied and it is known that they may differ depending on the Hg chemical species. In this chapter, we emphasize the neurotoxic effects of Hg during brain development. The immature brain is more susceptible to Hg exposure, since all the Hg chemical forms, not only the organic ones, can harm it. The possible consequences of Hg exposure during the early stages of development, the additive effects with other co-occurring neurotoxicants, and the known mechanisms of action and targets will be addressed in this chapter.
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Affiliation(s)
- Cláudia S Oliveira
- Programa de Pós-graduação em Ciências Biológicas: Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Pablo A Nogara
- Programa de Pós-graduação em Ciências Biológicas: Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Daniel M P Ardisson-Araújo
- Programa de Pós-graduação em Ciências Biológicas: Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
- Laboratório de Virologia de Insetos, Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, NY, USA
| | - João B T Rocha
- Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - José G Dórea
- Professor Emeritus, Faculdade de Ciências da Saúde, Universidade de Brasília, Brasília, DF, Brazil
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Andrew AS, Chen CY, Caller TA, Tandan R, Henegan PL, Jackson BP, Hall BP, Bradley WG, Stommel EW. Toenail mercury Levels are associated with amyotrophic lateral sclerosis risk. Muscle Nerve 2018; 58:10.1002/mus.26055. [PMID: 29314106 PMCID: PMC6034986 DOI: 10.1002/mus.26055] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 12/27/2017] [Accepted: 12/29/2017] [Indexed: 12/12/2022]
Abstract
INTRODUCTION Mercury is a neurotoxic metal that is potentially a risk factor for amyotrophic lateral sclerosis (ALS). Consumption of methylmercury contaminated fish is the primary source of US population exposure to mercury. METHODS We used inductively coupled plasma mass spectrometry to measure levels of mercury in toenail samples from patients with ALS (n = 46) and from controls (n = 66) as a biomarker of mercury exposure. RESULTS Patients with ALS had higher toenail mercury levels (odds ratio 2.49, 95% confidence interval 1.18-5.80, P = 0.024) compared with controls, adjusted for age and sex. We also estimated the amount of mercury consumed from finfish and shellfish and found toenail mercury levels elevated overall among patients with ALS and controls in the top quartile for consumption (P = 0.018). DISCUSSION Biomarker data show that ALS is associated with increased with mercury levels, which were related to estimated methylmercury intake via fish. Replication of these associations in additional populations is warranted. Muscle Nerve, 2018.
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Affiliation(s)
- Angeline S. Andrew
- Department of Neurology, Geisel School of Medicine at Dartmouth, Hanover, NH
| | - Celia Y. Chen
- Departments of Biological Sciences, Earth Science, Dartmouth College, Hanover, NH
| | - Tracie A. Caller
- Cheyenne Regional Medical Center, Medical Specialty Clinic, Cheyenne, WY
| | - Rup Tandan
- Department of Neurological Sciences, University of Vermont Medical Center, Burlington, VT
| | - Patricia L. Henegan
- Department of Neurology, Geisel School of Medicine at Dartmouth, Hanover, NH
| | - Brian P. Jackson
- Departments of Biological Sciences, Earth Science, Dartmouth College, Hanover, NH
| | - Brenda P. Hall
- Department of Neurology, Geisel School of Medicine at Dartmouth, Hanover, NH
| | - Walter G. Bradley
- Department of Neurology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Elijah W. Stommel
- Department of Neurology, Geisel School of Medicine at Dartmouth, Hanover, NH
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Abstract
Background Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterised by a rapid loss of lower and upper motor neurons. As a complex disease, the ageing process and complicated gene-environment interactions are involved in the majority of cases. Main body Significant advances have been made in unravelling the genetic susceptibility to ALS with massively parallel sequencing technologies, while environmental insults remain a suspected but largely unexplored source of risk. Several studies applying the strategy of Mendelian randomisation have strengthened the link between environmental insults and ALS, but none so far has proved conclusive. We propose a new ALS model which links the current knowledge of genetic factors, ageing and environmental insults. This model provides a mechanism as to how ALS is initiated, with environmental insults playing a critical role. Conclusion The available evidence has suggested that inherited defect(s) could cause mitochondrial dysfunction, which would establish the primary susceptibility to ALS. Further study of the underlying mechanism may shed light on ALS pathogenesis. Environmental insults are a critical trigger for ALS, particularly in the aged individuals with other toxicant susceptible genes. The identification of ALS triggers could lead to preventive strategies for those individuals at risk.
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Affiliation(s)
- Bing Yu
- Sydney Medical School (Central), The University of Sydney, Camperdown, NSW 2006 Australia.,Department of Medical Genomics, Royal Prince Alfred Hospital and NSW Health Pathology, Camperdown, NSW 2050 Australia
| | - Roger Pamphlett
- Discipline of Pathology, Brain and Mind Centre, The University of Sydney, 94 Mallett St, Camperdown, NSW 2050 Australia.,Department of Neuropathology, Royal Prince Alfred Hospital, Camperdown, NSW 2050 Australia
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De Benedetti S, Lucchini G, Del Bò C, Deon V, Marocchi A, Penco S, Lunetta C, Gianazza E, Bonomi F, Iametti S. Blood trace metals in a sporadic amyotrophic lateral sclerosis geographical cluster. Biometals 2017; 30:355-365. [PMID: 28337565 DOI: 10.1007/s10534-017-0011-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 03/18/2017] [Indexed: 11/28/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal disorder with unknown etiology, in which genetic and environmental factors interplay to determine the onset and the course of the disease. Exposure to toxic metals has been proposed to be involved in the etiology of the disease either through a direct damage or by promoting oxidative stress. In this study we evaluated the concentration of a panel of metals in serum and whole blood of a small group of sporadic patients, all living in a defined geographical area, for which acid mine drainage has been reported. ALS prevalence in this area is higher than in the rest of Italy. Results were analyzed with software based on artificial neural networks. High concentrations of metals (in particular Se, Mn and Al) were associated with the disease group. Arsenic serum concentration resulted lower in ALS patients, but it positively correlated with disease duration. Comet assay was performed to evaluate endogenous DNA damage that resulted not different between patients and controls. Up to now only few studies considered geographically well-defined clusters of ALS patients. Common geographical origin among patients and controls gave us the chance to perform metallomic investigations under comparable conditions of environmental exposure. Elaboration of these data with software based on machine learning processes has the potential to be extremely useful to gain a comprehensive view of the complex interactions eventually leading to disease, even in a small number of subjects.
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Affiliation(s)
- Stefano De Benedetti
- Department of Food, Environmental and Nutritional Sciences (DEFENS), Division of Chemical and Biomolecular Sciences, University of Milan, 20133, Milan, Italy
| | - Giorgio Lucchini
- Department of Agricultural and Environmental Sciences (DiSAA), University of Milan, 20133, Milan, Italy
| | - Cristian Del Bò
- Department of Food, Environmental and Nutritional Sciences (DEFENS), Division of Human Nutrition, University of Milan, 20133, Milan, Italy
| | - Valeria Deon
- Department of Food, Environmental and Nutritional Sciences (DEFENS), Division of Human Nutrition, University of Milan, 20133, Milan, Italy
| | - Alessandro Marocchi
- Medical Genetics Unit, Department of Laboratory Medicine, Niguarda Ca' Granda Hospital, 20162, Milan, Italy
| | - Silvana Penco
- Medical Genetics Unit, Department of Laboratory Medicine, Niguarda Ca' Granda Hospital, 20162, Milan, Italy
| | - Christian Lunetta
- Neuromuscular Omnicentre (NEMO), Fondazione Serena Onlus, Niguarda Ca' Granda Hospital, 20162, Milan, Italy
| | - Elisabetta Gianazza
- Laboratory of Biochemistry and Computational Biophysics, Department of Pharmacological and Biomolecular Sciences (DiSFeB), University of Milan, Via G. Balzaretti 9, 20133, Milan, Italy
| | - Francesco Bonomi
- Department of Food, Environmental and Nutritional Sciences (DEFENS), Division of Chemical and Biomolecular Sciences, University of Milan, 20133, Milan, Italy.
| | - Stefania Iametti
- Department of Food, Environmental and Nutritional Sciences (DEFENS), Division of Chemical and Biomolecular Sciences, University of Milan, 20133, Milan, Italy
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Clewett DV, Lee TH, Greening S, Ponzio A, Margalit E, Mather M. Neuromelanin marks the spot: identifying a locus coeruleus biomarker of cognitive reserve in healthy aging. Neurobiol Aging 2016; 37:117-126. [PMID: 26521135 PMCID: PMC5134892 DOI: 10.1016/j.neurobiolaging.2015.09.019] [Citation(s) in RCA: 129] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 09/18/2015] [Accepted: 09/23/2015] [Indexed: 12/21/2022]
Abstract
Leading a mentally stimulating life may build up a reserve of neural and mental resources that preserve cognitive abilities in late life. Recent autopsy evidence links neuronal density in the locus coeruleus (LC), the brain's main source of norepinephrine, to slower cognitive decline before death, inspiring the idea that the noradrenergic system is a key component of reserve (Robertson, I. H. 2013. A noradrenergic theory of cognitive reserve: implications for Alzheimer's disease. Neurobiol. Aging. 34, 298-308). Here, we tested this hypothesis using neuromelanin-sensitive magnetic resonance imaging to visualize and measure LC signal intensity in healthy younger and older adults. Established proxies of reserve, including education, occupational attainment, and verbal intelligence, were linearly correlated with LC signal intensity in both age groups. Results indicated that LC signal intensity was significantly higher in older than younger adults and significantly lower in women than in men. Consistent with the LC-reserve hypothesis, both verbal intelligence and a composite reserve score were positively associated with LC signal intensity in older adults. LC signal intensity was also more strongly associated with attentional shifting ability in older adults with lower cognitive reserve. Together these findings link in vivo estimates of LC neuromelanin signal intensity to cognitive reserve in normal aging.
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Affiliation(s)
- David V Clewett
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA, USA.
| | - Tae-Ho Lee
- Department of Psychology, University of Southern California, Los Angeles, CA, USA
| | - Steven Greening
- Department of Psychology, University of Southern California, Los Angeles, CA, USA; Davis School of Gerontology, University of Southern California, Los Angeles, CA, USA; Department of Psychology, Louisiana State University, Baton Rouge, LA, USA
| | - Allison Ponzio
- Davis School of Gerontology, University of Southern California, Los Angeles, CA, USA
| | - Eshed Margalit
- Dornsife College of Letters and Sciences, University of Southern California, Los Angeles, CA, USA
| | - Mara Mather
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA, USA; Department of Psychology, University of Southern California, Los Angeles, CA, USA; Davis School of Gerontology, University of Southern California, Los Angeles, CA, USA
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Akintunde JK, Oboh G. Subchronic exposure to leachate activates key markers linked with neurological disorder in Wistar male rat. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:18541-18553. [PMID: 26362636 DOI: 10.1007/s11356-015-5327-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 08/27/2015] [Indexed: 06/05/2023]
Abstract
The linking of various environmental chemicals exposure to neurodegenerative disorders is current. This study was undertaken to elucidate the toxic effects and the underlying biochemical mechanism of leachate obtained from Elewi Odo municipal battery recycling site (EOMABRL) using key markers of neuronal damage in rat via an oral route. Analysis of the concentrations of heavy metals showed that lead, cadmium, nickel, chromium, manganese, and iron were higher than the acceptable limits set by the regulatory authority-the World Health Organization. Whereas, copper, zinc, and cobalt were lower than permissible limits. EOMABRL was administered at 0, 20, 40, 60, 80, and 100% concentrations to adult male rats for 60 days. An in vitro study was also carried out in the cerebellum to assess cholinesterase biochemistry assays. Following exposure, brain was collected to determine the antioxidant status. EOMABRL administration significantly increased superoxide dismutase (SOD) and catalase (CAT) activities, and a sequential decrease in reduced glutathione (GSH) level with a concomitant increase in the accumulation of hydrogen peroxide (H2O2) and malondialdehyde (MDA) level was observed, when compared with the control. The treated rat had a significant (P < 0.05) increase in the activities of acetycholinesterase (AChE) and butyrylcholinesterase (BuChE). Taken together, these findings conclude that some possible mechanisms by which EOMABRL elicits neuronal disorder in male rat could be through the activation of AChE and BuChE and induction of oxidative stress with necrosis of neuronal cells.
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Affiliation(s)
- J K Akintunde
- Functional Foods, Nutraceuticals and Phytomedicine Research Laboratory, Department of Biochemistry, Federal University of Technology, P.M.B. 704, Akure, 340001, Nigeria.
- Drug Metabolism and Molecular Environmental Toxicology Research Laboratory, Biochemistry Unit, Department of Biosciences and Biotechnology, College of Pure and Applied Sciences, Kwara State University, Malete, P.M.B. 1530, Ilorin, Nigeria.
| | - G Oboh
- Functional Foods, Nutraceuticals and Phytomedicine Research Laboratory, Department of Biochemistry, Federal University of Technology, P.M.B. 704, Akure, 340001, Nigeria.
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Locus ceruleus neurons in people with autism contain no histochemically-detectable mercury. Biometals 2015; 29:171-5. [PMID: 26613607 PMCID: PMC4735248 DOI: 10.1007/s10534-015-9898-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 11/21/2015] [Indexed: 01/11/2023]
Abstract
Exposure to environmental mercury has been proposed to play a part in autism. Mercury is selectively taken up by the human locus ceruleus, a region of the brain that has been implicated in autism. We therefore looked for the presence of mercury in the locus ceruleus of people who had autism, using the histochemical technique of autometallography which can detect nanogram amounts of mercury in tissues. In addition, we sought evidence of damage to locus ceruleus neurons in autism by immunostaining for hyperphosphorylated tau. No mercury was found in any neurons of the locus ceruleus of 6 individuals with autism (5 male, 1 female, age range 16–48 years). Mercury was present in locus ceruleus neurons in 7 of 11 (64 %) age-matched control individuals who did not have autism, which is significantly more than in individuals with autism. No increase in numbers of locus ceruleus neurons containing hyperphosphorylated tau was detected in people with autism. In conclusion, most people with autism have not been exposed early in life to quantities of mercury large enough to be found later in adult locus ceruleus neurons. Human locus ceruleus neurons are sensitive indicators of mercury exposure, and mercury appears to remain in these neurons indefinitely, so these findings do not support the hypothesis that mercury neurotoxicity plays a role in autism.
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Meltz Steinberg K, Nicholas TJ, Koboldt DC, Yu B, Mardis E, Pamphlett R. Whole genome analyses reveal no pathogenetic single nucleotide or structural differences between monozygotic twins discordant for amyotrophic lateral sclerosis. Amyotroph Lateral Scler Frontotemporal Degener 2015; 16:385-92. [PMID: 25960086 DOI: 10.3109/21678421.2015.1040029] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The contribution of genetic and environmental factors to the pathogenesis of sporadic amyotrophic lateral sclerosis (ALS) remains unclear. To investigate the genetic component of the disease, we performed whole genome sequencing on ALS discordant monozygotic twins. Illumina whole genome sequencing on white blood cell DNA of five ALS-discordant monozygotic twin pairs (10 samples in total) yielded ∼30x coverage per individual. All single nucleotide variants, indels, and structural variants (copy number variants, inversions and translocations) were called and evaluated for functional consequence, evolutionary conservation, population frequency and overlap with known ALS associated variants and genes. Results showed that no validated discordant coding or regulatory single nucleotide variants or indels were found, and nor were any genome-wide discordant structural variants detected. Concordant variants of particular interest were: 1) two rare, highly-conserved heterozygous non-synonymous variants in SYT9 and EWSR1, genes previously associated with ALS (out of 2044 rare heterozygous variants detected); 2) three rare homozygous missense variants; and 3) three novel copy number deletions that overlapped genes. In conclusion, no convincing coding or regulatory nucleotide or genome-wide structural differences were found between ALS discordant monozygotic twins. The results suggest that more work is needed to elucidate possible environmental, epigenetic, oligogenic and somatic genetic factors that could underlie susceptibility to sporadic ALS.
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Affiliation(s)
- Karyn Meltz Steinberg
- a The Genome Institute, Washington University School of Medicine, St. Louis , Missouri , USA
| | - Thomas J Nicholas
- a The Genome Institute, Washington University School of Medicine, St. Louis , Missouri , USA
| | - Daniel C Koboldt
- a The Genome Institute, Washington University School of Medicine, St. Louis , Missouri , USA
| | - Bing Yu
- b Department of Medical Genomics , Royal Prince Alfred Hospital and Sydney Medical School, The University of Sydney , New South Wales , Australia
| | - Elaine Mardis
- a The Genome Institute, Washington University School of Medicine, St. Louis , Missouri , USA
| | - Roger Pamphlett
- c The Stacey MND Laboratory, Discipline of Pathology, Sydney Medical School, The Brain & Mind Research Institute, The University of Sydney , New South Wales , Australia
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Krey A, Kwan M, Chan HM. In vivo and in vitro changes in neurochemical parameters related to mercury concentrations from specific brain regions of polar bears (Ursus maritimus). ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2014; 33:2463-2471. [PMID: 25264143 DOI: 10.1002/etc.2685] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 02/27/2014] [Accepted: 07/11/2014] [Indexed: 06/03/2023]
Abstract
Mercury (Hg) has been detected in polar bear brain tissue, but its biological effects are not well known. Relationships between Hg concentrations and neurochemical enzyme activities and receptor binding were assessed in the cerebellum, frontal lobes, and occipital lobes of 24 polar bears collected from Nunavik (Northern Quebec), Canada. The concentration-response relationship was further studied with in vitro experiments using pooled brain homogenate of 12 randomly chosen bears. In environmentally exposed brain samples, there was no correlative relationship between Hg concentration and cholinesterase (ChE) activity or muscarinic acetylcholine receptor (mAChR) binding in any of the 3 brain regions. Monoamine oxidase (MAO) activity in the occipital lobe showed a negative correlative relationship with total Hg concentration. In vitro experiments, however, demonstrated that Hg (mercuric chloride and methylmercury chloride) can inhibit ChE and MAO activities and muscarinic mAChR binding. These results show that Hg can alter neurobiochemical parameters but the current environmental Hg exposure level does have an effect on the neurochemistry of polar bears from northern Canada.
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Affiliation(s)
- Anke Krey
- Natural Resources and Environmental Studies, University of Northern British Columbia, Prince George, British Columbia, Canada
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New perspectives on oxidized genome damage and repair inhibition by pro-oxidant metals in neurological diseases. Biomolecules 2014; 4:678-703. [PMID: 25036887 PMCID: PMC4192668 DOI: 10.3390/biom4030678] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 06/24/2014] [Accepted: 06/25/2014] [Indexed: 12/23/2022] Open
Abstract
The primary cause(s) of neuronal death in most cases of neurodegenerative diseases, including Alzheimer's and Parkinson's disease, are still unknown. However, the association of certain etiological factors, e.g., oxidative stress, protein misfolding/aggregation, redox metal accumulation and various types of damage to the genome, to pathological changes in the affected brain region(s) have been consistently observed. While redox metal toxicity received major attention in the last decade, its potential as a therapeutic target is still at a cross-roads, mostly because of the lack of mechanistic understanding of metal dyshomeostasis in affected neurons. Furthermore, previous studies have established the role of metals in causing genome damage, both directly and via the generation of reactive oxygen species (ROS), but little was known about their impact on genome repair. Our recent studies demonstrated that excess levels of iron and copper observed in neurodegenerative disease-affected brain neurons could not only induce genome damage in neurons, but also affect their repair by oxidatively inhibiting NEIL DNA glycosylases, which initiate the repair of oxidized DNA bases. The inhibitory effect was reversed by a combination of metal chelators and reducing agents, which underscore the need for elucidating the molecular basis for the neuronal toxicity of metals in order to develop effective therapeutic approaches. In this review, we have focused on the oxidative genome damage repair pathway as a potential target for reducing pro-oxidant metal toxicity in neurological diseases.
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