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Philibert A, Tousignant B, Fillion M, Da Silva J, Mergler D. Characterizing visual field loss from past mercury exposure in an Indigenous riverine community (Grassy Narrows First Nation, Canada): a cluster-based approach. Environ Health 2024; 23:81. [PMID: 39375679 PMCID: PMC11457346 DOI: 10.1186/s12940-024-01119-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2024] [Accepted: 09/23/2024] [Indexed: 10/09/2024]
Abstract
BACKGROUND Between 1962 and 1975, a chlor-alkali plant in Canada discharged approximately 9 metric tons of mercury (Hg) into the Wabigoon River. Over the following decades, biomarkers of Hg exposure of persons from Grassy Narrows First Nation (Asubpeeschoseewagong Anishinabek), located downriver from the discharge, reflected Hg concentrations in fish. Hg exposure is known to target the calcarine fissure, resulting in visual field (VF) loss. Most studies and clinical reports focus solely on peripheral VF loss; little is known about the impact of Hg on the central and paracentral portions. The present study sought to characterize the patterns of VF loss with respect to past and current Hg. METHODS A 28-year hair-Hg (HHg) database, created from a 1970-97 government biomonitoring program, served to select study participants with ≥ 4 year-based HHg measurements (n = 81). Blood-Hg was assessed for current exposure. Light sensitivity thresholds across the VF were analyzed monocularly, using a Humphrey Field Analyzer (HFA). Following post-hoc exclusions, based on HFA interpretation indices, 65 participants were retained. Both eyes were combined for analyses (n = 130 eyes). Unsupervised hierarchical clustering of HFA plot data was used to identify patterns of VF loss. A series of mixed effects models (MEM) were performed to test the associations for current Hg exposure with respect to HFA interpretation indices and clusters, as well as for longitudinal past Hg exposure. RESULTS The clustering approach decomposed the light sensitivity deficits into 5 concentric clusters, with greatest loss in the peripheral clusters. No relation was observed between any of the cluster scores and current blood-Hg. VF deficits increased with past Hg exposure. Longitudinal MEM showed that HHg was significantly (p < 0.05) associated with all peripheral, paracentral, and central cluster scores, as well as with HFA interpretation indices. CONCLUSIONS Past Hg exposure in Grassy Narrows First Nation was associated with present day VF loss. The cluster-based location-specific approach identified patterns of VF loss associated with long-term Hg exposure, in both the peripheral and the central areas. The functional implications of this type of visual loss should be investigated.
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Affiliation(s)
- Aline Philibert
- Centre de recherche interdisciplinaire sur le bien-être, la santé, la société et l'environnement (CINBIOSE), CP 8888, Université du Québec À Montréal, Succ. Centreville, Montréal, Québec, H3C 3P8, Canada
| | - Benoit Tousignant
- School of Optometry, Université de Montréal, 3744 Jean-Brillant, Montréal, Québec, H3T 1P1, Canada
- Department of Social and Preventive Medicine, School of Public Health, Université de Montréal, 7101 Avenue du Parc, Montreal, QC, H3N 1X9, Canada
| | - Myriam Fillion
- Département Science et Technologie, Université TÉLUQ, 5800 Saint-Denis St, Montréal, Québec, H2S 3L4, Canada
| | - Judy Da Silva
- Grassy Narrows First Nation, General Delivery, Grassy Narrows, Ontario, P0X 1B0, Canada
| | - Donna Mergler
- Centre de recherche interdisciplinaire sur le bien-être, la santé, la société et l'environnement (CINBIOSE), CP 8888, Université du Québec À Montréal, Succ. Centreville, Montréal, Québec, H3C 3P8, Canada.
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Petroff RL, Grant KS, Burbacher TM. The Role of Nonhuman Primates in Neurotoxicology Research: Preclinical Models and Experimental Methods. Curr Protoc 2023; 3:e698. [PMID: 36912610 PMCID: PMC10084743 DOI: 10.1002/cpz1.698] [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: 03/14/2023]
Abstract
Although noteworthy progress has been made in developing alternatives to animal testing, nonhuman primates still play a critical role in advancing biomedical research and will likely do so for many years. Core similarities between monkeys and humans in genetics, physiology, reproduction, development, and behavior make them excellent models for translational studies relevant to human health. This unit is designed to specifically address the role of nonhuman primates in neurotoxicology research and outlines the specialized assessments that can be used to measure exposure-related changes at the structural, chemical, cellular, molecular, and functional levels. © 2023 Wiley Periodicals LLC.
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Affiliation(s)
- Rebekah L Petroff
- Department of Environmental & Occupational Health Sciences (DEOHS), University of Washington, Seattle, Washington
| | - Kimberly S Grant
- Department of Environmental & Occupational Health Sciences (DEOHS), University of Washington, Seattle, Washington
| | - Thomas M Burbacher
- Department of Environmental & Occupational Health Sciences (DEOHS), University of Washington, Seattle, Washington
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Seewagen CL. The threat of global mercury pollution to bird migration: potential mechanisms and current evidence. ECOTOXICOLOGY (LONDON, ENGLAND) 2020; 29:1254-1267. [PMID: 30159636 DOI: 10.1007/s10646-018-1971-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/18/2018] [Indexed: 06/08/2023]
Abstract
Mercury is a global pollutant that has been widely shown to adversely affect reproduction and other endpoints related to fitness and health in birds, but almost nothing is known about its effects on migration relative to other life cycle processes. Here I consider the physiological and histological effects that mercury is known to have on non-migrating birds and non-avian vertebrates to identify potential mechanisms by which mercury might hinder migration performance. I posit that the broad ability of mercury to inactivate enzymes and compromise the function of other proteins is a single mechanism by which mercury has strong potential to disrupt many of the physiological processes that make long-distance migration possible. In just this way alone, there is reason to expect mercury to interfere with navigation, flight endurance, oxidative balance, and stopover refueling. Navigation and flight could be further affected by neurotoxic effects of mercury on the brain regions that process geomagnetic information from the visual system and control biomechanics, respectively. Interference with photochemical reactions in the retina and decreases in scotopic vision sensitivity caused by mercury also have the potential to disrupt visual-based magnetic navigation. Finally, migration performance and possibly survival might be limited by the immunosuppressive effects of mercury on birds at a time when exposure to novel pathogens and parasites is great. I conclude that mercury pollution is likely to be further challenging what is already often the most difficult and perilous phase of a migratory bird's annual cycle, potentially contributing to global declines in migratory bird populations.
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Affiliation(s)
- Chad L Seewagen
- Great Hollow Nature Preserve & Ecological Research Center, 225 Route 37, New Fairfield, CT, USA.
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Abdelzaher LA, Hussein OA, Ashry IEM. The Novel Potential Therapeutic Utility of Montelukast in Alleviating Autistic Behavior Induced by Early Postnatal Administration of Thimerosal in Mice. Cell Mol Neurobiol 2020; 41:129-150. [PMID: 32303879 DOI: 10.1007/s10571-020-00841-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Accepted: 04/01/2020] [Indexed: 12/14/2022]
Abstract
BACKGROUND AND AIM: Thimerosal (THIM) is a mercury-containing preservative widely used in many biological and medical products including many vaccines. It has been accused of being a possible etiological factor for some neurodevelopmental disorders such as autistic spectrum disorders (ASDs). In our study, the potential therapeutic effect of montelukast, a leukotriene receptor antagonist used to treat seasonal allergies and asthma, on THIM mice model (ASDs model) was examined. METHODOLOGY Newborn mice were randomly distributed into three groups: (Group 1) Control (Cont.) group received saline injections. (Group 2) THIM-treated (THIM) group received THIM intramuscular (IM) at a dose of 3000 μg Hg/kg on postnatal days 7, 9, 11, and 15. (Group 3) Montelukast-treated (Monte) group received THIM followed by montelukast sodium (10 mg/kg/day) intraperitoneal (IP) for 3 weeks. Mice were evaluated for growth development, social interactions, anxiety, locomotor activity, and cognitive function. Brain histopathology, alpha 7 nicotinic acetylcholine receptors (α7nAChRs), nuclear factor kappa B p65 (NF-κB p65), apoptotic factor (Bax), and brain injury markers were evaluated as well. RESULTS THIIM significantly impaired social activity and growth development. Montelukast mitigated THIM-induced social deficit probably through α7nAChRs upregulation, NF-κB p65, Bax, and brain injury markers downregulation, thus suppressing THIM-induced neuronal toxicity and inflammation. CONCLUSION Neonatal exposure to THIM can induce growth retardation and abnormal social interactions similar to those observed in ASDs. Some of these abnormalities could be ameliorated by montelukast via upregulation of α7nAChRs that inhibited NF-κB activation and significant suppression of neuronal injury and the associated apoptosis.
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Affiliation(s)
- Lobna A Abdelzaher
- Department of Pharmacology, Faculty of Medicine, Assiut University, Assiut, Egypt.
| | - Ola A Hussein
- Department of Histology, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - I E M Ashry
- Department of Pharmacology, Faculty of Medicine, Assiut University, Assiut, Egypt
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Maqbool F, Bahadar H, Hassani S, Niaz K, Baeeri M, Rahimifard M, Ghasemi-Niri SF, Abdollahi M. Biochemical evidence on the potential role of methyl mercury in hepatic glucose metabolism through inflammatory signaling and free radical pathways. J Cell Biochem 2019; 120:16195-16205. [PMID: 31081130 DOI: 10.1002/jcb.28899] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 03/12/2019] [Accepted: 03/22/2019] [Indexed: 12/18/2022]
Abstract
Methylmercury (MeHg) is an extremely important environmental toxicant posing serious health risks to human health and a big source of environmental pollutant. Numerous evidence available showing a link between nervous system toxicity and MeHg exposure. Other forms of mercury are reason of metabolic toxic effects and alteration of DNA in the human body. The sources of exposure could be occupational or other environmental settings. In the present study MeHg was orally gavaged to mice, at doses of 2.5, 5, and 10 mg/kg for 4 weeks. Fasting hyperglycemia, activity of hepatic phoshphoenolpyruvate carboxykinase and glucose 6-phoshphate were reported high as compared to control group. Inflammatory markers like, tumor necrosis factor α, the actual end product of inflammatory mediators' cascade pathway was also raised in comparison to control group. Hyperinsulinemia observed in serum showed clear understanding of mercury induced insulin resistance. Moreover, tissue damage due to increased oxidative stress markers like, hepatic lipid peroxidation, 8-deoxygunosine, reactive oxygen species, and carbonyl groups was significantly higher as compared to control group. MeHg caused a significant reduction in antioxidant markers like ferric reducing antioxidant power and total thiol molecules. The present study highlighted that activity of key enzymes involved in glucose metabolism is changed, owing to MeHg induced toxicity in the liver. Induction of similar toxic effects assumed to be stimulated by the production of high quantity free radicals.
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Affiliation(s)
- Faheem Maqbool
- Toxicology and Diseases Group, The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences, Tehran, Iran.,Department of Toxicology and Pharmacology, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
| | - Haji Bahadar
- Toxicology and Diseases Group, The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences, Tehran, Iran.,Department of Toxicology and Pharmacology, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran.,Department of Pharmacology, Institute of Basic Medical Sciences, Khyber Medical University, Peshawar, Pakistan
| | - Shokoufeh Hassani
- Toxicology and Diseases Group, The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences, Tehran, Iran.,Department of Toxicology and Pharmacology, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
| | - Kamal Niaz
- Toxicology and Diseases Group, The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences, Tehran, Iran.,Department of Toxicology and Pharmacology, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
| | - Maryam Baeeri
- Toxicology and Diseases Group, The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences, Tehran, Iran.,Department of Toxicology and Pharmacology, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
| | - Mahban Rahimifard
- Toxicology and Diseases Group, The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences, Tehran, Iran.,Department of Toxicology and Pharmacology, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
| | - Seyedeh Farnaz Ghasemi-Niri
- Toxicology and Diseases Group, The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences, Tehran, Iran.,Department of Toxicology and Pharmacology, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Abdollahi
- Toxicology and Diseases Group, The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences, Tehran, Iran.,Department of Toxicology and Pharmacology, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
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Cartier C, Warembourg C, Monfort C, Rouget F, Limon G, Durand G, Cordier S, Saint-Amour D, Chevrier C. Children’s contrast sensitivity function in relation to organophosphate insecticide prenatal exposure in the mother-child PELAGIE cohort. Neurotoxicology 2018; 67:161-168. [DOI: 10.1016/j.neuro.2018.05.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 05/15/2018] [Accepted: 05/16/2018] [Indexed: 01/11/2023]
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Morran SAM, Elliott JE, Young JML, Eng ML, Basu N, Williams TD. Ecologically-relevant exposure to methylmercury during early development does not affect adult phenotype in zebra finches (Taeniopygia guttata). ECOTOXICOLOGY (LONDON, ENGLAND) 2018; 27:259-266. [PMID: 29313303 DOI: 10.1007/s10646-017-1890-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/16/2017] [Indexed: 06/07/2023]
Abstract
Methylmercury causes behavioural and reproductive effects in adult mammals via early developmental exposure. Similar studies in birds are limited and mostly focussed on aquatic systems, but recent work has reported high blood mercury concentrations in terrestrial, passerine songbirds. We used the zebra finch (Taeniopygia guttata) as a model to explore the long-term effects of early developmental exposure to methylmercury exposure. Chicks were dosed orally with either the vehicle control, 0.0315 µg Hg/g bw/day, or 0.075 µg Hg/g bw/day throughout the nestling period (days 1-21 post-hatching). We then measured (a) short-term effects on growth, development, and behaviour (time to self-feeding, neophobia) until 30 days of age (independence), and (b) long-term effects on courtship behaviour and song (males) and reproduction (females) once methylmercury-exposed birds reached sexual maturity (90 days post-hatching). High methylmercury treated birds had mean blood mercury of 0.734 ± 0.163 µg/g at 30 days post-hatching, within the range of values reported for field-sampled songbirds at mercury contaminated sites. However, there were no short-term effects of treatment on growth, development, and behaviour of chicks, and no long-term effects on courtship behaviour and song in males or reproductive performance in females. These results suggest that the nestling period is not a critical window for sensitivity to mercury exposure in zebra finches. Growing nestlings can reduce blood mercury levels through somatic growth and depuration into newly growing feathers, and as a result they might actually be less susceptible compared to adult birds receiving the same level of exposure.
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Affiliation(s)
- Spencer A M Morran
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
| | - John E Elliott
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
- Environment and Climate Change Canada, Science & Technology Branch, Pacific Wildlife Research Centre, Delta, BC, Canada
| | - Jessica M L Young
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
| | - Margaret L Eng
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
- University of Saskatchewan, Saskatoon, SK, Canada
| | - Niladri Basu
- Faculty of Agricultural and Environmental Sciences, McGill University, Ste. Anne de Bellevue, QC, Canada
| | - Tony D Williams
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada.
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Bellante A, D'Agostino F, Traina A, Piazzese D, Milazzo MF, Sprovieri M. Hg and Se exposure in brain tissues of striped dolphin (Stenella coeruleoalba) and bottlenose dolphin (Tursiops truncatus) from the Tyrrhenian and Adriatic Seas. ECOTOXICOLOGY (LONDON, ENGLAND) 2017; 26:250-260. [PMID: 28108889 DOI: 10.1007/s10646-017-1759-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/03/2017] [Indexed: 06/06/2023]
Abstract
In this study we analyzed Hg and Se concentrations in dolphin brain tissues of fifteen specimens of striped dolphin (Stenella coeruleoalba) and eight specimens of bottlenose dolphin (Tursiops truncatus) stranded in the Tyrrhenian and Adriatic Seas, in order to assess the toxicological risks associated with Hg exposure. High Hg concentrations were found in brain tissues of both analyzed specie (1.86-243 mg/kg dw for striped dolphin and 2.1-98.7 mg/kg dw for bottlenose dolphin), exceeding levels associated with marine mammals neurotoxicity. Althougth the results clearly suggest that the protective effects of Se against Hg toxicity occur in cetaceans' brain tissues, a molar excess of mercury with respect to selenium was found, particularly in adult specimens of Stenella coeruleoalba. On contrary, negligible neurotoxicological risks were found for Tursiops truncatus specimens, due to detoxification processes. Data obtained allowed to prove a more marked neurotoxicological risk for adult specimens of Stenella coeruleoalba in both Tyrrhenian and Adriatic Seas.
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Affiliation(s)
- Antonio Bellante
- Dipartimento di Scienze della Terra e del Mare (DiSTeM), Università degli Studi di Palermo, CoNISMa -Palermo, Via Archirafi, 26, 90123, Palermo, Italy.
| | - Fabio D'Agostino
- CNR-Istituto per l'Ambiente Marino Costiero, Via del Mare 3, Capo Granitola, Campobello di Mazara, TP, 91021, Italy
| | - Anna Traina
- CNR-Istituto per l'Ambiente Marino Costiero, Via del Mare 3, Capo Granitola, Campobello di Mazara, TP, 91021, Italy
| | - Daniela Piazzese
- Dipartimento di Scienze della Terra e del Mare (DiSTeM), Università degli Studi di Palermo, CoNISMa -Palermo, Via Archirafi, 26, 90123, Palermo, Italy
| | - Maria Francesca Milazzo
- Dipartimento di Ingegneria (Dip.Inge.), Università degli Studi di Messina, Contrada Di Dio, 98166, Messina, Italy
| | - Mario Sprovieri
- CNR-Istituto per l'Ambiente Marino Costiero, Via del Mare 3, Capo Granitola, Campobello di Mazara, TP, 91021, Italy
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Assessment of neuroanatomical and behavioural effects of in ovo methylmercury exposure in zebra finches ( Taeniopygia guttata ). Neurotoxicology 2017; 59:33-39. [DOI: 10.1016/j.neuro.2017.01.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 01/03/2017] [Accepted: 01/04/2017] [Indexed: 12/25/2022]
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Kobiela ME, Cristol DA, Swaddle JP. Risk-taking behaviours in zebra finches affected by mercury exposure. Anim Behav 2015. [DOI: 10.1016/j.anbehav.2015.02.024] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Orenstein STC, Thurston SW, Bellinger DC, Schwartz JD, Amarasiriwardena CJ, Altshul LM, Korrick SA. Prenatal organochlorine and methylmercury exposure and memory and learning in school-age children in communities near the New Bedford Harbor Superfund site, Massachusetts. ENVIRONMENTAL HEALTH PERSPECTIVES 2014; 122:1253-9. [PMID: 25062363 PMCID: PMC4216164 DOI: 10.1289/ehp.1307804] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 07/24/2014] [Indexed: 05/22/2023]
Abstract
BACKGROUND Polychlorinated biphenyls (PCBs), organochlorine pesticides, and methylmercury (MeHg) are environmentally persistent with adverse effects on neurodevelopment. However, especially among populations with commonly experienced low levels of exposure, research on neurodevelopmental effects of these toxicants has produced conflicting results. OBJECTIVES We assessed the association of low-level prenatal exposure to these contaminants with memory and learning. METHODS We studied 393 children, born between 1993 and 1998 to mothers residing near a PCB-contaminated harbor in New Bedford, Massachusetts. Cord serum PCB, DDE (dichlorodiphenyldichloroethylene), and maternal peripartum hair mercury (Hg) levels were measured to estimate prenatal exposure. Memory and learning were assessed at 8 years of age (range, 7-11 years) using the Wide Range Assessment of Memory and Learning (WRAML), age-standardized to a mean ± SD of 100 ± 15. Associations with each WRAML index-Visual Memory, Verbal Memory, and Learning-were examined with multivariable linear regression, controlling for potential confounders. RESULTS Although cord serum PCB levels were low (sum of four PCBs: mean, 0.3 ng/g serum; range, 0.01-4.4), hair Hg levels were typical of the U.S. fish-eating population (mean, 0.6 μg/g; range, 0.3-5.1). In multivariable models, each microgram per gram increase in hair Hg was associated with, on average, decrements of -2.8 on Visual Memory (95% CI: -5.0, -0.6, p = 0.01), -2.2 on Learning (95% CI: -4.6, 0.2, p = 0.08), and -1.7 on Verbal Memory (95% CI: -3.9, 0.6, p = 0.14). There were no significant adverse associations of PCBs or DDE with WRAML indices. CONCLUSIONS These results support an adverse relationship between low-level prenatal MeHg exposure and childhood memory and learning, particularly visual memory.
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Affiliation(s)
- Sara T C Orenstein
- Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA
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Altered social interactions in male juvenile cynomolgus monkeys prenatally exposed to bisphenol A. Neurotoxicol Teratol 2014; 44:46-52. [DOI: 10.1016/j.ntt.2014.05.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 05/14/2014] [Accepted: 05/20/2014] [Indexed: 12/17/2022]
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Burbacher TM, Grant KS, Worlein J, Ha J, Curnow E, Juul S, Sackett GP. Four decades of leading-edge research in the reproductive and developmental sciences: the Infant Primate Research Laboratory at the University of Washington National Primate Research Center. Am J Primatol 2013; 75:1063-83. [PMID: 23873400 PMCID: PMC5452618 DOI: 10.1002/ajp.22175] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 05/31/2013] [Accepted: 05/31/2013] [Indexed: 12/20/2022]
Abstract
The Infant Primate Research Laboratory (IPRL) was established in 1970 at the University of Washington as a visionary project of Dr. Gene (Jim) P. Sackett. Supported by a collaboration between the Washington National Primate Research Center and the Center on Human Development and Disability, the IPRL operates under the principle that learning more about the causes of abnormal development in macaque monkeys will provide important insights into the origins and treatment of childhood neurodevelopmental disabilities. Over the past 40 years, a broad range of research projects have been conducted at the IPRL. Some have described the expression of normative behaviors in nursery-reared macaques while others have focused on important biomedical themes in child health and development. This article details the unique scientific history of the IPRL and the contributions produced by research conducted in the laboratory. Past and present investigations have explored the topics of early rearing effects, low-birth-weight, prematurity, birth injury, epilepsy, prenatal neurotoxicant exposure, viral infection (pediatric HIV), diarrheal disease, vaccine safety, and assisted reproductive technologies. Data from these studies have helped advance our understanding of both risk and resiliency in primate development. New directions of research at the IPRL include the production of transgenic primate models using our embryonic stem cell-based technology to better understand and treat heritable forms of human intellectual disabilities such as fragile X.
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Affiliation(s)
- Thomas M. Burbacher
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, 98195 USA
- Center on Human Development and Disability, University of Washington, Seattle, WA, 98195 USA
- Washington National Primate Research Center, University of Washington, Seattle, WA 98195 USA
| | - Kimberly S. Grant
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, 98195 USA
- Center on Human Development and Disability, University of Washington, Seattle, WA, 98195 USA
- Washington National Primate Research Center, University of Washington, Seattle, WA 98195 USA
| | - Julie Worlein
- Washington National Primate Research Center, University of Washington, Seattle, WA 98195 USA
| | - James Ha
- Washington National Primate Research Center, University of Washington, Seattle, WA 98195 USA
- Department of Psychology, School of Arts and Sciences, University of Washington, Seattle, WA, 98195 USA
| | - Eliza Curnow
- Washington National Primate Research Center, University of Washington, Seattle, WA 98195 USA
| | - Sandra Juul
- Center on Human Development and Disability, University of Washington, Seattle, WA, 98195 USA
- Department of Pediatrics, School of Medicine, University of Washington, Seattle, WA, 98195 USA
| | - Gene P. Sackett
- Center on Human Development and Disability, University of Washington, Seattle, WA, 98195 USA
- Washington National Primate Research Center, University of Washington, Seattle, WA 98195 USA
- Department of Psychology, School of Arts and Sciences, University of Washington, Seattle, WA, 98195 USA
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Cowden J, Padnos B, Hunter D, MacPhail R, Jensen K, Padilla S. Developmental exposure to valproate and ethanol alters locomotor activity and retino-tectal projection area in zebrafish embryos. Reprod Toxicol 2012; 33:165-73. [PMID: 22244950 DOI: 10.1016/j.reprotox.2011.11.111] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 11/03/2011] [Accepted: 11/24/2011] [Indexed: 11/17/2022]
Abstract
Given the minimal developmental neurotoxicity data available for the large number of new and existing chemicals, there is a critical need for alternative methods to identify and prioritize chemicals for further testing. We outline a developmental neurotoxicity screening approach using zebrafish embryos. Embryos were exposed to nominal concentrations of either valproate or ethanol then examined for lethality, malformation, nervous system structure and locomotor activity. Developmental valproate exposure caused locomotor activity changes at concentrations that did not result in malformations and showed a concentration-dependent decrease in retino-tectal projection area in the optic tectum. Developmental ethanol exposure also affected retino-tectal projection area at concentrations below those concentrations causing malformations. As both valproate and ethanol are known human developmental neurotoxicants, these results add to the growing body of evidence showing the potential utility of zebrafish in screening compounds for mammalian developmental neurotoxicity.
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Affiliation(s)
- John Cowden
- Integrated Systems Toxicology Division United States Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
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Janzen R, Schwarzer M, Sperling M, Vogel M, Schwerdtle T, Karst U. Adduct formation of Thimerosal with human and rat hemoglobin: a study using liquid chromatography coupled to electrospray time-of-flight mass spectrometry (LC/ESI-TOF-MS). Metallomics 2011; 3:847-52. [PMID: 21706086 DOI: 10.1039/c1mt00043h] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Thimerosal (THI) is used as a preservative in many vaccines throughout the world. Ethylmercury (EtHg(+)), released from THI in aqueous media, has a high affinity to thiol functions of proteins. In blood, hemoglobin is a likely target protein because of its high abundance and its several free thiol functions. In comparison to hemoglobin of human origin, hemoglobin of rats exhibits almost twice as many free thiol groups, which might lead to different binding behavior and therefore a limited comparability between the situation in man and in rats, which are frequently used as models for mercury species toxicity investigations. Thus, the adduct formation of EtHg(+) with hemoglobin of humans and rats was compared under simulated physiological conditions by using gradient reversed-phase liquid chromatography (LC) with electrospray time-of-flight mass spectrometry (ESI-TOF-MS) detection. The binding stoichiometry correlated with the number of free thiols in the α- and β-chain of hemoglobin. The use of rats to verify the safety of additives in vaccines like Thimerosal is therefore doubtful and should be reevaluated.
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Affiliation(s)
- Rasmus Janzen
- University of Münster, Institute of Inorganic and Analytical Chemistry, Corrensstr. 30, 48149 Münster, Germany
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16
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Farina M, Rocha JBT, Aschner M. Mechanisms of methylmercury-induced neurotoxicity: evidence from experimental studies. Life Sci 2011; 89:555-63. [PMID: 21683713 DOI: 10.1016/j.lfs.2011.05.019] [Citation(s) in RCA: 303] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 04/22/2011] [Accepted: 05/13/2011] [Indexed: 02/08/2023]
Abstract
Neurological disorders are common, costly, and can cause enduring disability. Although mostly unknown, a few environmental toxicants are recognized causes of neurological disorders and subclinical brain dysfunction. One of the best known neurotoxins is methylmercury (MeHg), a ubiquitous environmental toxicant that leads to long-lasting neurological and developmental deficits in animals and humans. In the aquatic environment, MeHg is accumulated in fish, which represent a major source of human exposure. Although several episodes of MeHg poisoning have contributed to the understanding of the clinical symptoms and histological changes elicited by this neurotoxicant in humans, experimental studies have been pivotal in elucidating the molecular mechanisms that mediate MeHg-induced neurotoxicity. The objective of this mini-review is to summarize data from experimental studies on molecular mechanisms of MeHg-induced neurotoxicity. While the full picture has yet to be unmasked, in vitro approaches based on cultured cells, isolated mitochondria and tissue slices, as well as in vivo studies based mainly on the use of rodents, point to impairment in intracellular calcium homeostasis, alteration of glutamate homeostasis and oxidative stress as important events in MeHg-induced neurotoxicity. The potential relationship among these events is discussed, with particular emphasis on the neurotoxic cycle triggered by MeHg-induced excitotoxicity and oxidative stress. The particular sensitivity of the developing brain to MeHg toxicity, the critical role of selenoproteins and the potential protective role of selenocompounds are also discussed. These concepts provide the biochemical bases to the understanding of MeHg neurotoxicity, contributing to the discovery of endogenous and exogenous molecules that counteract such toxicity and provide efficacious means for ablating this vicious cycle.
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Affiliation(s)
- Marcelo Farina
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
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17
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Fillion M, Philibert A, Mertens F, Lemire M, Passos CJS, Frenette B, Guimarães JRD, Mergler D. Neurotoxic sequelae of mercury exposure: an intervention and follow-up study in the Brazilian Amazon. ECOHEALTH 2011; 8:210-222. [PMID: 22160443 DOI: 10.1007/s10393-011-0710-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 05/12/2011] [Accepted: 05/18/2011] [Indexed: 05/31/2023]
Abstract
Since 1995, the Caruso Project used an Ecosystem Approach to Human Health to examine mercury (Hg) exposure in fish-eating communities in the Brazilian Amazon and develop interventions to maximise nutrition from traditional diet and minimise toxic risk. In 1995, 2000 and 2006, this study followed fish consumption, Hg levels, and visual and motor functions in 31 villagers. Questionnaires gathered information on socio-demographics and diet. Hair Hg (H-Hg) levels were measured. Visual acuity, colour vision, manual dexterity and grip strength were assessed. Data was analysed using general linear models of repeated measures. Total fish consumption, similar in 1995 and 2000, decreased in 2006. Carnivorous fish consumption initially decreased and then remained stable, whereas non-carnivorous fish consumption first increased and then decreased. H-Hg declined from 17.6 to 7.8 μg/g. Visual functions showed a significant decrease over time, with those with H-Hg ≥ 20 μg/g in 1995 showing greater loss. Motor functions showed initial improvement and then returned to the 1995 performance level. Decrease in Hg exposure is attributed to the intervention and socio-economic changes in the village. While there may be a certain reversibility of motor deficits, visual capacities may decrease progressively with respect to exposure prior to the intervention.
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Affiliation(s)
- Myriam Fillion
- Centre de recherche interdisciplinaire sur la biologie, la santé, la société et l'environnement (CINBIOSE), Université du Québec à Montréal, C.P. 8888, Succ. Centre-Ville, Montreal, QC, H3C 3P8, Canada
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18
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Weiss B. Lead, manganese, and methylmercury as risk factors for neurobehavioral impairment in advanced age. Int J Alzheimers Dis 2010; 2011:607543. [PMID: 21234365 PMCID: PMC3014718 DOI: 10.4061/2011/607543] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Revised: 10/28/2010] [Accepted: 11/24/2010] [Indexed: 11/20/2022] Open
Abstract
Contamination of the environment by metals is recognized as a threat to health. One of their targets is the brain, and the adverse functional effects they induce are reflected by neurobehavioral assessments. Lead, manganese, and methylmercury are the metal contaminants linked most comprehensively to such disorders. Because many of these adverse effects can appear later in life, clues to the role of metals as risk factors for neurodegenerative disorders should be sought in the exposure histories of aging populations. A review of the available literature offers evidence that all three metals can produce, in advanced age, manifestations of neurobehavioral dysfunction associated with neurodegenerative disease. Among the critical unresolved questions is timing; that is, during which periods of the lifespan, including early development, do environmental exposures lay the foundations for their ultimate effects?
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Affiliation(s)
- Bernard Weiss
- Department of Environmental Medicine, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA
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19
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Olczak M, Duszczyk M, Mierzejewski P, Bobrowicz T, Majewska MD. Neonatal administration of thimerosal causes persistent changes in mu opioid receptors in the rat brain. Neurochem Res 2010; 35:1840-7. [PMID: 20803069 PMCID: PMC2957583 DOI: 10.1007/s11064-010-0250-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2010] [Indexed: 10/26/2022]
Abstract
Thimerosal added to some pediatric vaccines is suspected in pathogenesis of several neurodevelopmental disorders. Our previous study showed that thimerosal administered to suckling rats causes persistent, endogenous opioid-mediated hypoalgesia. Here we examined, using immunohistochemical staining technique, the density of μ-opioid receptors (MORs) in the brains of rats, which in the second postnatal week received four i.m. injections of thimerosal at doses 12, 240, 1,440 or 3,000 μg Hg/kg. The periaqueductal gray, caudate putamen and hippocampus were examined. Thimerosal administration caused dose-dependent statistically significant increase in MOR densities in the periaqueductal gray and caudate putamen, but decrease in the dentate gyrus, where it was accompanied by the presence of degenerating neurons and loss of synaptic vesicle marker (synaptophysin). These data document that exposure to thimerosal during early postnatal life produces lasting alterations in the densities of brain opioid receptors along with other neuropathological changes, which may disturb brain development.
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Affiliation(s)
- Mieszko Olczak
- Department of Pharmacology and Physiology of the Nervous System, Institute of Psychiatry and Neurology, Sobieskiego 9 str., 02-957 Warsaw, Poland
- Department of Forensic Medicine, Medical University of Warsaw, Oczki 1 str., 02-007 Warsaw, Poland
| | - Michalina Duszczyk
- Department of Pharmacology and Physiology of the Nervous System, Institute of Psychiatry and Neurology, Sobieskiego 9 str., 02-957 Warsaw, Poland
| | - Pawel Mierzejewski
- Department of Pharmacology and Physiology of the Nervous System, Institute of Psychiatry and Neurology, Sobieskiego 9 str., 02-957 Warsaw, Poland
| | - Teresa Bobrowicz
- Department of Neuropathology, Institute of Psychiatry and Neurology, 02-957 Warsaw, Poland
| | - Maria Dorota Majewska
- Department of Pharmacology and Physiology of the Nervous System, Institute of Psychiatry and Neurology, Sobieskiego 9 str., 02-957 Warsaw, Poland
- Department of Biology and Environmental Science, University of Cardinal Stefan Wyszynski, Wóycickiego Str. 1/3, 01-815 Warsaw, Poland
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20
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Yu X, Robinson JF, Sidhu JS, Hong S, Faustman EM. A system-based comparison of gene expression reveals alterations in oxidative stress, disruption of ubiquitin-proteasome system and altered cell cycle regulation after exposure to cadmium and methylmercury in mouse embryonic fibroblast. Toxicol Sci 2010; 114:356-77. [PMID: 20061341 PMCID: PMC2840217 DOI: 10.1093/toxsci/kfq003] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 12/28/2009] [Indexed: 01/28/2023] Open
Abstract
Environmental and occupational exposures to heavy metals such as methylmercury (MeHg) and cadmium (Cd) pose significant health risks to humans, including neurotoxicity. The underlying mechanisms of their toxicity, however, remain to be fully characterized. Our previous studies with Cd and MeHg have demonstrated that the perturbation of the ubiquitin-proteasome system (UPS) was associated with metal-induced cytotoxicity and apoptosis. We conducted a microarray-based gene expression analysis to compare metal-altered gene expression patterns with a classical proteasome inhibitor, MG132 (0.5 microM), to determine whether the disruption of the UPS is a critical mechanism of metal-induced toxicity. We treated mouse embryonic fibroblast cells at doses of MeHg (2.5 microM) and Cd (5.0 microM) for 24 h. The doses selected were based on the neutral red-based cell viability assay where initial statistically significant decreases in variability were detected. Following normalization of the array data, we employed multilevel analysis tools to explore the data, including group comparisons, cluster analysis, gene annotations analysis (gene ontology analysis), and pathway analysis using GenMAPP and Ingenuity Pathway Analysis (IPA). Using these integrated approaches, we identified significant gene expression changes across treatments within the UPS (Uchl1 and Ube2c), antioxidant and phase II enzymes (Gsta2, Gsta4, and Noq1), and genes involved in cell cycle regulation pathways (ccnb1, cdc2a, and cdc25c). Furthermore, pathway analysis revealed significant alterations in genes implicated in Parkinson's disease pathogenesis following metal exposure. This study suggests that these pathways play a critical role in the development of adverse effects associated with metal exposures.
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Affiliation(s)
| | | | | | | | - Elaine M. Faustman
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, 98105
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21
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Aschner* M, Onishchenko N, Ceccatelli S. Toxicology of Alkylmercury Compounds. ORGANOMETALLICS IN ENVIRONMENT AND TOXICOLOGY 2010. [DOI: 10.1039/9781849730822-00403] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Methylmercury is a global pollutant and potent neurotoxin whose abundance in the food chain mandates additional studies on the consequences and mechanisms of its toxicity to the central nervous system. Formulation of our new hypotheses was predicated on our appreciation for (a) the remarkable affinity of mercurials for the anionic form of sulfhydryl (-SH) groups, and (b) the essential role of thiols in protein biochemistry. The present chapter addresses pathways to human exposure of various mercury compounds, highlighting their neurotoxicity and potential involvement in neurotoxic injury and neurodegenerative changes, both in the developing and senescent brain. Mechanisms that trigger these effects are discussed in detail.
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Affiliation(s)
- Michael Aschner*
- Vanderbilt University School of Medicine, Department of Pediatrics Pharmacology, and the Kennedy Center for Research on Human Development Nashville TN 37232 USA
| | | | - Sandra Ceccatelli
- Karolinska Institute, Department of Neuroscience SE-17177 Stockholm Sweden
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22
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Are neuropathological conditions relevant to ethylmercury exposure? Neurotox Res 2009; 18:59-68. [PMID: 19756911 DOI: 10.1007/s12640-009-9113-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Revised: 08/31/2009] [Accepted: 09/02/2009] [Indexed: 10/20/2022]
Abstract
Mercury and mercurial compounds are among the environmentally ubiquitous substances most toxic to both wildlife and humans. Once released into the environment from both natural and anthropogenic sources, mercury exists mainly as three different molecular species: elemental, inorganic, and organic. Potential health risks have been reported from exposure to all forms; however, of particular concern for human exposure relate to the potent neurotoxic effects of methylmercury (MeHg), especially for the developing nervous system. The general population is primarily exposed to MeHg by seafood consumption. In addition, some pharmaceuticals, including vaccines, have been, and some continue to be, a ubiquitous source of exposure to mercurials. A significant controversy has been whether the vaccine preservative ethylmercury thiosalicylate, commonly known as thimerosal, could cause the development of autism. In this review, we have discussed the hypothesis that exposure to thimerosal during childhood may be a primary cause of autism. The conclusion is that there are no reliable data indicating that administration of vaccines containing thimerosal is a primary cause of autism. However, one cannot rule out the possibility that the individual gene profile and/or gene-environment interactions may play a role in modulating the response to acquired risk by modifying the individual susceptibility.
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23
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Dasari S, Yuan Y. Low level postnatal methylmercury exposure in vivo alters developmental forms of short-term synaptic plasticity in the visual cortex of rat. Toxicol Appl Pharmacol 2009; 240:412-22. [PMID: 19664649 DOI: 10.1016/j.taap.2009.07.037] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Revised: 07/29/2009] [Accepted: 07/30/2009] [Indexed: 10/20/2022]
Abstract
Methylmercury (MeHg) has been previously shown to affect neurotransmitter release. Short-term synaptic plasticity (STP) is primarily related to changes in the probability of neurotransmitter release. To determine if MeHg affects STP development, we examined STP forms in the visual cortex of rat following in vivo MeHg exposure. Neonatal rats received 0 (0.9% NaCl), 0.75 or 1.5 mg/kg/day MeHg subcutaneously for 15 or 30 days beginning on postnatal day 5, after which visual cortical slices were prepared for field potential recordings. In slices prepared from rats treated with vehicle, field excitatory postsynaptic potentials (fEPSPs) evoked by paired-pulse stimulation at 20-200 ms inter-stimulus intervals showed a depression (PPD) of the second fEPSP (fEPSP2). PPD was also seen in slices prepared from rats after 15 day treatment with 0.75 or 1.5 mg/kg/day MeHg. However, longer duration treatment (30 days) with either dose of MeHg resulted in paired-pulse facilitation (PPF) of fEPSP2 in the majority of slices examined. PPF remained observable in slices prepared from animals in which MeHg exposure had been terminated for 30 days after completion of the initial 30 day MeHg treatment, whereas slices from control animals still showed PPD. MeHg did not cause any frequency- or region-preferential effect on STP. Manipulations of [Ca2+](e) or application of the GABA(A) receptor antagonist bicuculline could alter the strength and polarity of MeHg-induced changes in STP. Thus, these data suggest that low level postnatal MeHg exposure interferes with the developmental transformation of STP in the visual cortex, which is a long-lasting effect.
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Affiliation(s)
- Sameera Dasari
- Department of Pharmacology and Toxicology, B307A Life Science Building, Michigan State University, East Lansing, MI 48824-1317, USA
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24
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Newland MC, Paletz EM, Reed MN. Methylmercury and nutrition: adult effects of fetal exposure in experimental models. Neurotoxicology 2008; 29:783-801. [PMID: 18652843 PMCID: PMC2659504 DOI: 10.1016/j.neuro.2008.06.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2008] [Revised: 06/25/2008] [Accepted: 06/25/2008] [Indexed: 11/17/2022]
Abstract
Human exposure to the life-span developmental neurotoxicant, methylmercury (MeHg), is primarily via the consumption of fish or marine mammals. Fish are also excellent sources of important nutrients, including selenium and n-3 polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA). Laboratory models of developmental MeHg exposure can be employed to assess the roles of nutrients and MeHg and to identify potential mechanisms of action if the appropriate exposure measures are used. When maternal exposure is protracted, relationships between daily intake and brain mercury are consistent and orderly across species, even when large differences in blood:brain ratios exist. It is well established that low-level developmental MeHg produces sensory deficits. Recent studies also show that perseveration in reversal-learning tasks occurs after gestational exposures that produce low micromolar concentrations in the brain. A no-effect level has not been identified for this effect. These exposures do not affect the acquisition or performance of discrimination learning, set shifting (extradimensional shift), or memory. Reversal-learning deficits may be related to enhanced impact of reinforcers as measured using progressive ratio reinforcement schedules, an effect that could result in perseveration. Also reported is enhanced sensitivity to dopamine reuptake inhibitors and diminished sensitivity to pentobarbital, a GABA(A) agonist. Diets rich in PUFAs or selenium do not protect against MeHg's effects on reversal learning but, by themselves, may diminish variability in performance, enhance attention or psychomotor function and may confer some protection against age-related deficits in these areas. It is hypothesized that altered reward processing, dopamine and GABAergic neurotransmitter systems, and cortical regions associated with choice and perseveration are especially sensitive to developmental MeHg at low exposure levels. Human testing for MeHg's neurotoxicity should emphasize these behavioral domains.
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Affiliation(s)
- M Christopher Newland
- Department of Psychology, 226 Thach Hall, Auburn University, Auburn, AL 36849-5214, USA.
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25
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Weiss B. Chemobrain: a translational challenge for neurotoxicology. Neurotoxicology 2008; 29:891-8. [PMID: 18479752 DOI: 10.1016/j.neuro.2008.03.009] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2008] [Revised: 03/26/2008] [Accepted: 03/26/2008] [Indexed: 11/18/2022]
Abstract
Neurotoxicity is a frequent accompaniment of cancer chemotherapy, and held by many oncologists to be the major dose-limiting side effect. It appears in many forms, but attracted attention during the past decade primarily because of complaints by patients of impaired cognitive function they have labeled as "chemobrain". Neuropsychological testing confirmed the validity of these complaints and has generated a substantial literature examining different aspects of cognitive impairment in various clinical populations undergoing a variety of treatments. Cognitive impairment is far from the only manifestation of neurotoxicity induced by chemotherapy, however. It alters sensory function and motor function as well. A critical need for patients is a suite of methods that will enable clinicians to trace the onset and progression of neurotoxicity so as to guide and balance decisions about the course of chemotherapy. This commentary describes some of the potential methods and encourages neurotoxicologists to enlist their unique skills in the service of these needs.
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Affiliation(s)
- Bernard Weiss
- Department of Environmental Medicine, Environmental Health Sciences Center, and Center for Reproductive Epidemiology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA.
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26
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Castoldi AF, Onishchenko N, Johansson C, Coccini T, Roda E, Vahter M, Ceccatelli S, Manzo L. Neurodevelopmental toxicity of methylmercury: Laboratory animal data and their contribution to human risk assessment. Regul Toxicol Pharmacol 2008; 51:215-29. [PMID: 18482784 DOI: 10.1016/j.yrtph.2008.03.005] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2007] [Revised: 01/28/2008] [Accepted: 03/18/2008] [Indexed: 11/28/2022]
Abstract
Methylmercury (MeHg) is one of the most significant public health hazards. The clinical findings in the victims of the Japanese and Iraqi outbreaks have disclosed the pronounced susceptibility of the developing brain to MeHg poisoning. This notion has triggered worldwide scientific attention toward the long-term consequences of prenatal exposure on child development in communities with chronic low level dietary exposure. MeHg neurodevelopmental effects have been extensively investigated in laboratory animals under well-controlled exposure conditions. This article provides an updated overview of the main neuromorphological and neurobehavioral changes reported in non-human primates and rodents following developmental exposure to MeHg. Different aspects of MeHg's effects on the immature organism are reported, with particular reference to the delayed onset of symptoms and the persistency of central nervous system (CNS) injury/dysfunction. Particular attention is paid to the comparative toxicity assessment across species, and to the degree of concordance/discordance between human and animal data. The contribution of animal studies to define the role of potential effect modifiers and variables on MeHg dose-response relationships is also addressed. The ultimate goal is to discuss the relevance of laboratory animal results, as a complementary tool to human data, with regard to the human risk assessment process.
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Affiliation(s)
- Anna F Castoldi
- Toxicology Division, University of Pavia, Via Palestro 26, 27100 Pavia, Italy.
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27
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Johansson C, Castoldi AF, Onishchenko N, Manzo L, Vahter M, Ceccatelli S. Neurobehavioural and molecular changes induced by methylmercury exposure during development. Neurotox Res 2007; 11:241-60. [PMID: 17449462 DOI: 10.1007/bf03033570] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
There is an increasing body of evidence on the possible environmental influence on neurodevelopmental and neurodegenerative disorders. Both experimental and epidemiological studies have demonstrated the distinctive susceptibility of the developing brain to environmental factors such as lead, mercury and polychlorinated biphenyls at levels of exposure that have no detectable effects in adults. Methylmercury (MeHg) has long been known to affect neurodevelopment in both humans and experimental animals. Neurobehavioural effects reported include altered motoric function and memory and learning disabilities. In addition, there is evidence from recent experimental neurodevelopmental studies that MeHg can induce depression-like behaviour. Several mechanisms have been suggested from in vivo- and in vitro-studies, such as effects on neurotransmitter systems, induction of oxidative stress and disruption of microtubules and intracellular calcium homeostasis. Recent in vitro data show that very low levels of MeHg can inhibit neuronal differentiation of neural stem cells. This review summarises what is currently known about the neurodevelopmental effects of MeHg and consider the strength of different experimental approaches to study the effects of environmentally relevant exposure in vivo and in vitro.
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Affiliation(s)
- Carolina Johansson
- Division of Toxicology and Neurotoxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
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28
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From Animals to Humans: Models and Constructs. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/s0074-7750(05)30010-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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