1
|
Lin H, Wei Y, Li S, Mao X, Qin J, Su S, He T. Changes in transcriptome regulations of a marine rotifer Brachionus plicatilis under methylmercury stress. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART D, GENOMICS & PROTEOMICS 2024; 49:101177. [PMID: 38104474 DOI: 10.1016/j.cbd.2023.101177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 12/04/2023] [Accepted: 12/07/2023] [Indexed: 12/19/2023]
Abstract
Mercury (Hg), a heavy metal pollutant worldwide, can be transformed into methylmercury (MeHg) by various aquatic microorganisms in water, thus accumulating along the aquatic food chain and posing a particular challenge to human health. Zooplankton plays a crucial role in aquatic ecosystems and serves as a major component of the food chain. To evaluate the effects of MeHg on the rotifer Brachionus plicatilis and reveal the underlying mechanism of these effects, we exposed B. plicatilis to MeHg by either direct immersion or by feeding with MeHg-poisoned Chlorella pyrenoidesa, respectively, and conducted a transcriptomic analysis. The results showed that B. plicatilis directly exposed to MeHg by immersion showed significant enrichment of the glutathione metabolism pathway for detoxification of MeHg. In addition, the exposure to MeHg by feeding induced a significant enrichment of lysosome and notch signaling pathways of rotifers, supporting the hypothesis that MeHg can induce autophagy dysfunction in cells and disturb the nervous system of rotifers. In two different routes of MeHg exposure, the pathway of cytochrome P450 in rotifers showed significant enrichment for resisting MeHg toxicity. Our results suggest further studies on the potential mechanism and biological responses of MeHg toxicity in other links of the aquatic food chain.
Collapse
Affiliation(s)
- Hangyu Lin
- College of Fisheries, Southwest University, Chongqing 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, 400715, China
| | - Yanlin Wei
- College of Fisheries, Southwest University, Chongqing 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, 400715, China
| | - Songzhang Li
- College of Fisheries, Southwest University, Chongqing 400715, China
| | - Xiaodong Mao
- College of Fisheries, Southwest University, Chongqing 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, 400715, China
| | - Jianguang Qin
- College of Science and Engineering, Flinders University, South Australia 5001, Australia
| | - Shengqi Su
- College of Fisheries, Southwest University, Chongqing 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, 400715, China.
| | - Tao He
- College of Fisheries, Southwest University, Chongqing 400715, China; Key Laboratory of Freshwater Fish Reproduction and Development (Ministry of Education), Key Laboratory of Aquatic Science of Chongqing, 400715, China.
| |
Collapse
|
2
|
Kendricks DR, Boomhower SR, Newland MC. Adolescence as a sensitive period for neurotoxicity: Lifespan developmental effects of methylmercury. Pharmacol Biochem Behav 2022; 217:173389. [PMID: 35452710 DOI: 10.1016/j.pbb.2022.173389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 04/04/2022] [Accepted: 04/11/2022] [Indexed: 10/18/2022]
Abstract
Neurotoxicity resulting from the environmental contaminant, methylmercury (MeHg), is a source of concern for many human populations that rely heavily on the consumption of fish and rice as stable ingredients in the diet. The developmental period of exposure is important both to the qualitative effects of MeHg and to the dose required to produce those effects. MeHg exposure during the sensitive prenatal period causes deleterious and long-lasting changes in neurodevelopment at particularly low doses. The effects include a wide host of cognitive and behavioral outcomes expressed in adulthood and sometimes not until aging. However, neurotoxic outcomes of methylmercury when exposure occurs during adolescence are only recently revealing impacts on human populations and animal models. This review examines the current body of work and showcases the sensitivity of adolescence, a period that straddles early development and adulthood, to methylmercury neurotoxicity and the implications such toxicity has in our understanding of methylmercury's effects in human populations and animal models.
Collapse
Affiliation(s)
- Dalisa R Kendricks
- Department of Psychology, Auburn University, Auburn, AL, United States of America.
| | - Steven R Boomhower
- Gradient, Boston, MA, United States of America; Harvard Division of Continuing Education, Harvard University, Cambridge, MA, United States of America
| | | |
Collapse
|
3
|
Newell ME, Adhikari S, Halden RU. Systematic and state-of the science review of the role of environmental factors in Amyotrophic Lateral Sclerosis (ALS) or Lou Gehrig's Disease. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 817:152504. [PMID: 34971691 DOI: 10.1016/j.scitotenv.2021.152504] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 06/14/2023]
Abstract
The etiology of sporadic amyotrophic lateral sclerosis (ALS) is still unclear. We evaluate environmental factors suspected to be associated with ALS for their potential linkage to disease causality and to model geographic distributions of susceptible populations and expected cases worldwide. A PRISMA systematic literature review was performed 2021. Bradford Hill criteria were used to identify and rank environmental factors and a secondary review of ALS diagnoses in population studies and ALS case or cohort studies was conducted. Prevalence rate projection informed estimates of impacted regions and populations. Among 1710 papers identified, 258 met the inclusion criteria, of which 173 responded to at least one of nine Bradford Hill criteria among 83 literature-identified ALS environmental factors. Environmental determinants of ALS in order of decreasing significance were β-N-methylamino-L-alanine (BMAA), formaldehyde, selenium, and heavy metals including manganese, mercury, zinc, and copper. Murine animal models were the most common methodology for exploring environmental factors. Another line of investigation of 62 population exposure studies implicated the same group of environmental agents (mean odds ratios): BMAA (2.32), formaldehyde (1.54), heavy metals (2.99), manganese (3.85), mercury (2.74), and zinc (2.78). An age-adjusted incidence model estimated current total ALS cases globally at ~85,000 people compared to only ~1600 cases projected from the reported ALS incidence in the literature. Modeling with the prevalence microscope equation forecasted an increase in U.S. ALS cases from 16,707 confirmed in 2015 to ~22,650 projected for 2040. Two orthogonal methods employed implicate BMAA, formaldehyde, manganese, mercury, and zinc as environmental factors with strong ALS associations. ALS cases likely are significantly underreported globally, and high vulnerability exists in regions with large aging populations. Recent studies on other diseases with environmental determinants suggest the need to consider additional potential triggers and mechanisms, including exposures to microbial agents and epigenetic modifications.
Collapse
Affiliation(s)
- Melanie Engstrom Newell
- Biodesign Center for Environmental Health Engineering, Biodesign Institute, Building B, Arizona State University, 1001 S McAllister Ave, Tempe, AZ 85281-8101, USA; School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA.
| | - Sangeet Adhikari
- Biodesign Center for Environmental Health Engineering, Biodesign Institute, Building B, Arizona State University, 1001 S McAllister Ave, Tempe, AZ 85281-8101, USA; School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ, USA.
| | - Rolf U Halden
- Biodesign Center for Environmental Health Engineering, Biodesign Institute, Building B, Arizona State University, 1001 S McAllister Ave, Tempe, AZ 85281-8101, USA; School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, USA; School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ, USA; OneWaterOneHealth, Arizona State University Foundation, 1001 S. McAllister Avenue, Tempe, AZ 85287-8101, USA; Global Futures Laboratory, Arizona State University, 800 S. Cady Mall, Tempe, AZ 85281, USA.
| |
Collapse
|
4
|
Nascimento PC, Aragão WAB, Bittencourt LO, Silva MCF, Crespo-Lopez ME, Lima RR. Salivary parameters alterations after early exposure to environmental methylmercury: A preclinical study in offspring rats. J Trace Elem Med Biol 2021; 68:126820. [PMID: 34293649 DOI: 10.1016/j.jtemb.2021.126820] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 06/02/2021] [Accepted: 07/14/2021] [Indexed: 01/18/2023]
Abstract
BACKGROUND Methylmercury (MeHg) is still considered a global pollutant of major concern; thus, it becomes relevant to investigate and validate alternative diagnostic methods to track early-life human exposure. This study aimed to evaluate the salivary parameters and to characterize potential mechanisms of oxidative damage on the salivary glands (SG) of offspring rats after pre- and postnatal environmental-experimental MeHg exposure. METHODS Pregnant Wistar rats were daily exposed to 40 μg/kg MeHg during both gestational and lactation periods. Then, the saliva of offspring rats was analyzed in terms of flow rate, amylase activity, and total protein concentration. The SG of the offspring rats were dissected to perform the oxidative biochemistry analyses of antioxidant capacity against peroxyl radicals (ACAP), lipid peroxidation (LPO), and nitrite levels. RESULTS Exposure to MeHg significantly decreased the ACAP, increased LPO and nitrite levels, decreased salivary flow rate, amylase activity, and total protein concentration. CONCLUSION Saliva analyses can predict damages induced by early-life MeHg exposure and may be used as an auxiliary diagnostic method.
Collapse
Affiliation(s)
- Priscila Cunha Nascimento
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Para, Belém, PA, Brazil
| | - Walessa Alana Bragança Aragão
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Para, Belém, PA, Brazil
| | - Leonardo Oliveira Bittencourt
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Para, Belém, PA, Brazil
| | - Marcia Cristina Freitas Silva
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Para, Belém, PA, Brazil
| | - Maria Elena Crespo-Lopez
- Laboratory of Molecular Pharmacology, Institute of Biological Sciences, Federal University of Para, Belém, PA, Brazil
| | - Rafael Rodrigues Lima
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Para, Belém, PA, Brazil.
| |
Collapse
|
5
|
Peppriell AE, Gunderson JT, Krout IN, Vorojeikina D, Rand MD. Latent effects of early-life methylmercury exposure on motor function in Drosophila. Neurotoxicol Teratol 2021; 88:107037. [PMID: 34656729 DOI: 10.1016/j.ntt.2021.107037] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 09/25/2021] [Accepted: 10/10/2021] [Indexed: 12/27/2022]
Abstract
The developmental toxicant, methylmercury (MeHg), can elicit motor deficits that last well into adulthood. Recent studies using Drosophila showed that the developing musculature is sensitive to high doses of MeHg, where a larval feeding paradigm resulted in compromised myotendinous junction (MTJ) formation during development, by a mechanism involving the NG2 homologue, kon-tiki (kon). Low-dose exposures to MeHg that do not produce muscle pathology during development, nevertheless result in impaired flight behavior later in adult life. The present study evaluated the potential for relatively low-dose exposure to produce latent adult muscle pathology and motor impairments, as assayed by climbing and flight, as well as to evaluate molecular mechanisms that may contribute to motor deficits. Wildtype larvae were fed 0, 2, 2.5, or 5 μM MeHg laden food until eclosion. The effect of 5 μM MeHg on MTJ-related gene expression during pupal development was assessed via quantitative RT-qPCR analysis. Upon eclosion, adults were transferred to standard food bottles for 4, 11, or 30 days prior to motor testing. Survivorship (%) was determined from a subset of 200 flies per treatment. Average climbing speed (cm/s) was quantified 4-days post-eclosion (PE). Flight ability was assayed 11- or 30-days PE by measuring landing height (cm) of flies dropped into an adhesive-lined vertical column. In parallel, total body mercury was measured to estimate the influence of residual MeHg at the time of motor testing. Muscle morphology was assessed using immuno-fluorescence microscopy. Exposure to 5uM MeHg significantly reduced climbing speed, and flight ability 4 and 11 - days PE, respectively. While age-related flight deficits were seen in each sex, flight deficits due to MeHg persisted to 30-day PE timepoints exclusively in males. Expression of kon was upregulated across the window of pupal development essential to establishing adult MTJ. However, experimentally restricting the induction of comparable levels of kon to muscle during the same periods did not recapitulate the flight deficits, indicating that muscle-specific induction of kon alone is not sufficient to contribute to latent flight impairments. Adult flight muscle morphology of 11-day PE flies treated with 5 μM MeHg was indistinct from controls, implying muscle structure is not grossly perturbed to impair flight. Collectively, the current data suggest that developmental exposure to 5 μM MeHg reduces flight ability in each sex at 11 day-PE and that latent deficits at 30-day PE are male-specific. It remains to be determined whether the developing MTJ of Drosophila is a sensitive target of MeHg, and whether or not kon acts in conjunction with additional MTJ factors to constitute a MeHg target.
Collapse
Affiliation(s)
- Ashley E Peppriell
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA; ICF International, Durham, NC, USA.
| | - Jakob T Gunderson
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Ian N Krout
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Daria Vorojeikina
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Matthew D Rand
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| |
Collapse
|
6
|
de Oliveira RAA, Pinto BD, Rebouças BH, Ciampi de Andrade D, de Vasconcellos ACS, Basta PC. Neurological Impacts of Chronic Methylmercury Exposure in Munduruku Indigenous Adults: Somatosensory, Motor, and Cognitive Abnormalities. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph181910270. [PMID: 34639574 PMCID: PMC8507861 DOI: 10.3390/ijerph181910270] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 09/16/2021] [Accepted: 09/23/2021] [Indexed: 11/29/2022]
Abstract
There has been increasing evidence about mercury (Hg) contamination in traditional populations from the Amazon Basin due to illegal gold mining. The most concerning health impact is neurotoxicity caused by Hg in its organic form: methylmercury (MeHg). However, the severity and extent of the neurotoxic effects resulting from chronic environmental exposure to MeHg are still unclear. We conducted a clinical-epidemiological study to evaluate the neurological impacts of chronic MeHg exposure in Munduruku indigenous people, focusing on somatosensory, motor, and cognitive abnormalities. All participants were subjected to a systemized neurological exam protocol, including Brief Cognitive Screening Battery (BCSB), verbal fluency test, and Stick Design Test. After the examination, hair samples were collected to determine MeHg levels. Data collection took place between 29 October and 9 November 2019, in three villages (Sawré Muybu, Poxo Muybu, and Sawré Aboy) from Sawré Muybu Indigenous Land, Southwest of Pará state. One hundred and ten individuals >12 years old were included, 58 of which were men (52.7%), with an average age of 27.6 years (range from 12 to 72). Participants’ median MeHg level was 7.4 µg/g (average: 8.7; S.D: 4.5; range: 2.0–22.8). In Sawré Aboy village, the median MeHg level was higher (12.5 µg/g) than in the others, showing a significant statistical exposure gradient (Kruskal–Wallis test with p-value < 0.001). Cerebellar ataxia was observed in two participants with MeHg levels of 11.68 and 15.68 µg/g. Individuals with MeHg exposure level ≥10 µg/g presented around two-fold higher chances of cognitive deficits (RP: 2.2; CI 95%: 1.13–4.26) in BCSB, and in the verbal fluency test (RP: 2.0; CI 95%: 1.18–3.35). Furthermore, adolescents of 12 to 19 years presented three-fold higher chances of verbal development deficits, according to the fluency test (RP: 3.2; CI 95%: 1.06–9.42), than individuals of 20 to 24 years. The worsened motor and cognitive functions are suggestive of neurotoxicity due to chronic MeHg exposure. In conclusion, we believe monitoring and follow-up measures are necessary for chronic mercury exposed vulnerable people, and a basic care protocol should be established for contaminated people in the Brazilian Unified Health System.
Collapse
Affiliation(s)
- Rogério Adas Ayres de Oliveira
- Centro de Dor, Departamento de Neurologia, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo (USP), São Paulo 05403-000, Brazil; (R.A.A.d.O.); (B.D.P.); (B.H.R.); (D.C.d.A.)
| | - Bruna Duarte Pinto
- Centro de Dor, Departamento de Neurologia, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo (USP), São Paulo 05403-000, Brazil; (R.A.A.d.O.); (B.D.P.); (B.H.R.); (D.C.d.A.)
| | - Bruno Hojo Rebouças
- Centro de Dor, Departamento de Neurologia, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo (USP), São Paulo 05403-000, Brazil; (R.A.A.d.O.); (B.D.P.); (B.H.R.); (D.C.d.A.)
| | - Daniel Ciampi de Andrade
- Centro de Dor, Departamento de Neurologia, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo (USP), São Paulo 05403-000, Brazil; (R.A.A.d.O.); (B.D.P.); (B.H.R.); (D.C.d.A.)
| | - Ana Claudia Santiago de Vasconcellos
- Laboratório de Educação Profissional em Vigilância em Saúde, Escola Politécnica de Saúde Joaquim Venâncio, Fundação Oswaldo Cruz (EPSJV/Fiocruz), Rio de Janeiro 21040-900, Brazil;
| | - Paulo Cesar Basta
- Departamento de Endemias Samuel Pessoa, Escola Nacional de Saúde Pública, Fundação Oswaldo Cruz (ENSP/Fiocruz), Rio de Janeiro 21041-210, Brazil
- Correspondence: ; Tel.: +55-21-2598-2503
| |
Collapse
|
7
|
Nascimento PC, Ferreira MKM, Balbinot KM, Alves-Júnior SM, Viana Pinheiro JDJ, Silveira FM, Martins MD, Crespo-Lopez ME, Lima RR. Methylmercury-Induced Toxicopathologic Findings in Salivary Glands of Offspring Rats After Gestational and Lactational Exposure. Biol Trace Elem Res 2021; 199:2983-2991. [PMID: 33009984 DOI: 10.1007/s12011-020-02409-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 09/21/2020] [Indexed: 01/21/2023]
Abstract
Methylmercury (MeHg) is one of the main global pollutants. The vulnerability of fetus and newborn to MeHg-induced changes is extensively reported, making relevant investigation possible for alternative sample matrix for human biological monitoring for at this stage of life. This study aimed to characterize tissue change effects of environmental-experimental MeHg on salivary glands of offspring rats after pre- and postnatal exposure. For this, pregnant Wistar rats were orally exposed to MeHg (40 μg/kg BW/day) or only vehicle (control group), from the gestational period to the end of the lactation period. Salivary glands (SG) were collected from the offspring to analyze possible Hg levels and main findings by histopathological evaluations and CK19 and α-SMA immunostaining. The results indicated that Hg levels in SG of intoxicated offspring were associated with histologic abnormalities, such as acinar atrophy and an increase in the intercellular matrix among the acini, as well as damages in the architecture of epithelium and myoepithelial cells, evidenced by a decrease in immunostaining area. Thus, this is the first study to show in the literature the toxicopathologic findings on SG of offspring after pre- and postnatal exposure to MeHg. Moreover, it presents the SG as an attractive target to futures studies, mainly in children exposed to environmentally relevant doses.
Collapse
Affiliation(s)
- Priscila Cunha Nascimento
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Para, Rua Augusto Corrêa n° 1, Campus do Guamá, Belém, Pará, 66075-110, Brazil
| | - Maria Karolina Martins Ferreira
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Para, Rua Augusto Corrêa n° 1, Campus do Guamá, Belém, Pará, 66075-110, Brazil
| | | | - Sérgio Melo Alves-Júnior
- School of Dentistry, Institute of Health Sciences, Federal University of Pará, Belém, Pará, Brazil
| | | | - Felipe Martins Silveira
- Department of Oral Pathology, School of Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Manoela Domingues Martins
- Department of Oral Pathology, School of Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Maria Elena Crespo-Lopez
- Laboratory of Molecular Pharmacology, Institute of Biological Sciences, Federal University of Pará, Belém, Pará, Brazil
| | - Rafael Rodrigues Lima
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Para, Rua Augusto Corrêa n° 1, Campus do Guamá, Belém, Pará, 66075-110, Brazil.
| |
Collapse
|
8
|
Abbott LC, Nigussie F. Mercury Toxicity and Neurogenesis in the Mammalian Brain. Int J Mol Sci 2021; 22:ijms22147520. [PMID: 34299140 PMCID: PMC8305137 DOI: 10.3390/ijms22147520] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/12/2021] [Accepted: 07/05/2021] [Indexed: 01/21/2023] Open
Abstract
The mammalian brain is formed from billions of cells that include a wide array of neuronal and glial subtypes. Neural progenitor cells give rise to the vast majority of these cells during embryonic, fetal, and early postnatal developmental periods. The process of embryonic neurogenesis includes proliferation, differentiation, migration, the programmed death of some newly formed cells, and the final integration of differentiated neurons into neural networks. Adult neurogenesis also occurs in the mammalian brain, but adult neurogenesis is beyond the scope of this review. Developing embryonic neurons are particularly susceptible to neurotoxicants and especially mercury toxicity. This review focused on observations concerning how mercury, and in particular, methylmercury, affects neurogenesis in the developing mammalian brain. We summarized information on models used to study developmental mercury toxicity, theories of pathogenesis, and treatments that could be used to reduce the toxic effects of mercury on developing neurons.
Collapse
Affiliation(s)
- Louise C. Abbott
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, 4458 TAMU, College Station, TX 77843-4458, USA
- Correspondence: ; Tel.: +1-541-254-0779
| | - Fikru Nigussie
- College of Veterinary Medicine, Oregon State University, 700 SW 30th Street, Corvallis, OR 97331, USA;
| |
Collapse
|
9
|
Vejdovszky K, Mihats D, Griesbacher A, Wolf J, Steinwider J, Lueckl J, Jank B, Kopacka I, Rauscher-Gabernig E. Modified Reference Point Index (mRPI) and a decision tree for deriving uncertainty factors: A practical approach to cumulative risk assessment of food contaminant mixtures. Food Chem Toxicol 2019; 134:110812. [PMID: 31505235 DOI: 10.1016/j.fct.2019.110812] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 09/04/2019] [Accepted: 09/06/2019] [Indexed: 10/26/2022]
Abstract
Risk assessment of chemical mixtures remains a challenging task in all areas of food and consumer safety. So far, no general method has been developed that is best suited to several subject areas (e.g. food contaminants, additives and supplements, plant protection products). Especially for mixtures of food contaminants sophisticated methods are typically not applicable due to a general lack of complete toxicological data sets. We developed a new approach, the modified Reference Point Index (mRPI), that combines the advantages of the Hazard Index and the Reference Point Index. Furthermore, we developed a decision tree for the determination of specific uncertainty factors that makes the mRPI an easy to use method for cumulative risk assessment even in a data poor field such as food contaminants. To further characterise the estimated cumulative risks, the Maximum Cumulative Ratio (MCR) was adapted to be applied on the mRPI, and the modified Maximum Cumulative Ratio (mMCR) was established to identify whether the risks are dominated by a single substance. We present two case studies assessing the nephrotoxic and neurotoxic risks for the Austrian population originating from food contaminant mixtures. Calculations could not rule out potential cumulative risks, yet, they seemed to be dominated by single substances.
Collapse
Affiliation(s)
- Katharina Vejdovszky
- Department of Risk Assessment, Division of Data, Statistics & Risk Assessment, Austrian Agency for Health and Food Safety (AGES), Spargelfeldstraße 191, 1220, Vienna, Austria.
| | - Daniela Mihats
- Department of Data Management, Division of Data, Statistics & Risk Assessment, Austrian Agency for Health and Food Safety (AGES), Spargelfeldstraße 191, 1220, Vienna, Austria.
| | - Antonia Griesbacher
- Department of Statistics and Analytical Epidemiology, Division of Data, Statistics & Risk Assessment, Austrian Agency for Health and Food Safety (AGES), Spargelfeldstraße 191, 1220, Vienna, Austria.
| | - Josef Wolf
- Department of Data Management, Division of Data, Statistics & Risk Assessment, Austrian Agency for Health and Food Safety (AGES), Spargelfeldstraße 191, 1220, Vienna, Austria.
| | - Johann Steinwider
- Department of Risk Assessment, Division of Data, Statistics & Risk Assessment, Austrian Agency for Health and Food Safety (AGES), Spargelfeldstraße 191, 1220, Vienna, Austria
| | - Johannes Lueckl
- Department of Statistics and Analytical Epidemiology, Division of Data, Statistics & Risk Assessment, Austrian Agency for Health and Food Safety (AGES), Spargelfeldstraße 191, 1220, Vienna, Austria.
| | - Bernhard Jank
- Department of Food Safety and Consumer Protection, Federal Ministry of Labour, Social Affairs, Health and Consumer Protection, Radetzkystraße 2, 1030, Vienna, Austria.
| | - Ian Kopacka
- Department of Statistics and Analytical Epidemiology, Division of Data, Statistics & Risk Assessment, Austrian Agency for Health and Food Safety (AGES), Spargelfeldstraße 191, 1220, Vienna, Austria.
| | - Elke Rauscher-Gabernig
- Department of Risk Assessment, Division of Data, Statistics & Risk Assessment, Austrian Agency for Health and Food Safety (AGES), Spargelfeldstraße 191, 1220, Vienna, Austria.
| |
Collapse
|
10
|
Puty B, Leão LKR, Crespo-Lopez ME, Almeida APCPSC, Fagundes NCF, Maia LC, Lima RR. Association between methylmercury environmental exposure and neurological disorders: A systematic review. J Trace Elem Med Biol 2019; 52:100-110. [PMID: 30732869 DOI: 10.1016/j.jtemb.2018.12.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Revised: 11/27/2018] [Accepted: 12/03/2018] [Indexed: 01/23/2023]
Abstract
The mercury-related central nervous system disorders have been extensively studied on animal models and human beings. However, clinical evidences of which neurological changes are in fact associated with mercury exposure remains controversial. This systematic review (Prospero registration under the number CRD42016041760) aimed to elucidate the association of methylmercury (MeHg) exposure with neurological alteration in populations living in MeHg-endemic risk area. A systematic search was performed according to the Preferred Reporting Items for Systematic Review and Meta-Analysis criteria using available databases PubMed, LILACS, Scopus, Web of Science, The Cochrane Library, OpenGrey and Google Scholar. A search of the following terms: "methylmercury compounds", "organomercury compounds", "neurologic manifestations", "memory disorders", "neurobehavioral manifestations" and "communication disorders" were performed in a systematic way. Studies focusing on MeHg exposure and subsequent neurological alteration on humans (>13 years) were included. Evaluation of methodological quality and risk of bias as well as the level of evidence was performed. Our results have identified 470 studies and six articles were eligible for systematic review inclusion criteria. The studies suggested alterations related to the psychosensory, motor and coordination system, as well as motor speech, hearing, visual impairment, mood alterations and loss of intelligent quotient. Of all the six studies, two presented a high risk of bias, with methodological problems related to the confounding factors and all studies presented evidence level ranged from very low to low. In this way our results revealed that a definitive demonstration of an association of MeHg and neurological alterations in human beings is still a pending subject. Future studies in this topic should take into consideration more confident and reliable methods to answer this question.
Collapse
Affiliation(s)
- Bruna Puty
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Para, Belem, Brazil.
| | - Luana Ketlen Reis Leão
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Para, Belem, Brazil.
| | - Maria Elena Crespo-Lopez
- Laboratory of Molecular Pharmacology, Institute of Biological Sciences, Federal University of Para, Belem, Brazil.
| | | | | | - Lucianne Cople Maia
- Department of Pediatric Dentistry and Orthodontics, School of Dentistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
| | - Rafael Rodrigues Lima
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Para, Belem, Brazil.
| |
Collapse
|
11
|
Chen BY, Lung YC, Kuo CC, Liang FC, Tsai TL, Jiang DH, Satoh T, Jeng RJ. Novel Multifunctional Luminescent Electrospun Fluorescent Nanofiber Chemosensor-Filters and Their Versatile Sensing of pH, Temperature, and Metal Ions. Polymers (Basel) 2018; 10:E1259. [PMID: 30961184 PMCID: PMC6401977 DOI: 10.3390/polym10111259] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Revised: 11/08/2018] [Accepted: 11/09/2018] [Indexed: 11/24/2022] Open
Abstract
Novel multifunctional fluorescent chemosensors composed of electrospun (ES) nanofibers with high sensitivity toward pH, mercury ions (Hg2+), and temperature were prepared from poly(N-Isopropylacrylamide-co-N-methylolacrylamide-co-rhodamine derivative) (poly(NIPAAm-co-NMA-co-RhBN2AM)) by employing an electrospinning process. NIPAAm and NMA moieties provide hydrophilic and thermo-responsive properties (absorption of Hg2+ in aqueous solutions), and chemical cross-linking sites (stabilization of the fibrous structure in aqueous solutions), respectively. The fluorescent probe, RhBN2AM is highly sensitive toward pH and Hg2+. The synthesis of poly(NIPAAm-co-NMA-co-RhBN2AM) with different compositions was carried on via free-radical polymerization. ES nanofibers prepared from sensory copolymers with a 71.1:28.4:0.5 NIPAAm:NMA:RhBN2AM ratio (P3 ES nanofibers) exhibited significant color change from non-fluorescent to red fluorescence while sensing pH (the λPL, max exhibited a 4.8-fold enhancement) or Hg2+ (at a constant Hg2+ concentration (10-3 M), the λPL, max of P3-fibers exhibited 4.7-fold enhancement), and high reversibility of on/off switchable fluorescence emission at least five times when Hg2+ and ethylenediaminetetraacetic acid (EDTA) were sequentially added. The P3 ES nanofibrous membranes had a higher surface-to-volume ratio to enhance their performance than did the corresponding thin films. In addition, the fluorescence emission of P3 ES nanofibrous membranes exhibited second enhancement above the lower critical solution temperature. Thus, the ES nanofibrous membranes prepared from P3 with on/off switchable capacity and thermo-responsive characteristics can be used as a multifunctional sensory device for specific heavy transition metal (HTM) in aqueous solutions.
Collapse
Affiliation(s)
- Bo-Yu Chen
- Institute of Polymer Science and Engineering, National Taiwan University, 106 Taipei, Taiwan.
- Institute of Organic and Polymeric Materials, National Taipei University of Technology, 10608 Taipei, Taiwan.
| | - Yen-Chen Lung
- Institute of Organic and Polymeric Materials, National Taipei University of Technology, 10608 Taipei, Taiwan.
| | - Chi-Ching Kuo
- Institute of Organic and Polymeric Materials, National Taipei University of Technology, 10608 Taipei, Taiwan.
- Research and Development Center for Smart Textile Technology, National Taipei University of Technology, 10608 Taipei, Taiwan.
| | - Fang-Cheng Liang
- Institute of Organic and Polymeric Materials, National Taipei University of Technology, 10608 Taipei, Taiwan.
| | - Tien-Liang Tsai
- Institute of Organic and Polymeric Materials, National Taipei University of Technology, 10608 Taipei, Taiwan.
| | - Dai-Hua Jiang
- Institute of Organic and Polymeric Materials, National Taipei University of Technology, 10608 Taipei, Taiwan.
| | - Toshifumi Satoh
- Graduate School of Chemical Sciences and Engineering and Faculty of Engineering, Hokkaido University, Sapporo 060-8628, Japan.
| | - Ru-Jong Jeng
- Institute of Polymer Science and Engineering, National Taiwan University, 106 Taipei, Taiwan.
- Advanced Research Center for Green Materials Science and Technology, National Taiwan University, 106 Taipei, Taiwan.
| |
Collapse
|
12
|
Oliveira AN, Pinheiro AM, Belém-Filho IJA, Fernandes LMP, Cartágenes SC, Ribera PC, Fontes-Júnior EA, Crespo-Lopez ME, Monteiro MC, Lima MO, Maia CSF. Unravelling motor behaviour hallmarks in intoxicated adolescents: methylmercury subtoxic-dose exposure and binge ethanol intake paradigm in rats. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:21937-21948. [PMID: 29797195 DOI: 10.1007/s11356-018-2235-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 05/04/2018] [Indexed: 06/08/2023]
Abstract
Methylmercury (MeHg) is a hazardous environmental pollutant, affecting Amazon basin communities by anthropogenic activities. The exact safe level of MeHg exposure is unclear, despite the efforts of health international societies to avoid mercury (Hg) poisoning. Central nervous system is severely impacted by Hg intoxication, reflecting on motor impairment. In addition, alcohol has been associated to an overall brain damage. According to lifestyle of Amazon riverside communities, alcohol intake occurs frequently. Thus, we investigated if continuous MeHg exposure at low doses during adolescence displays motor deficits (experiment 1). In the experiment 2, we examine if the co-intoxication (i.e. MeHg plus ethanol exposure) during adolescence intensify motor damage. In the experiment 1, Wistar adolescent rats (31 days old) received chronic exposure to low dose (CELD) of MeHg (40 μg/kg/day) for 35 days. For the experiment 2, five sessions of alcohol binge drinking paradigm (3ON-4OFF; 3.0 g/kg/day) were employed associated to MeHg intoxication. Motor behaviour was evaluated by the open field, pole test, beam walking and rotarod paradigms. CELDS of MeHg display motor function damage, related to hypoactivity, bradykinesia-like behaviour, coordination deficits and motor learning impairment. Co-intoxication of MeHg plus ethanol reduced cerebellar Hg content, however also resulted in motor behavioural impairment, as well as additive effects on bradykinesia and fine motor evaluation.
Collapse
Affiliation(s)
- Aline Nascimento Oliveira
- Laboratório de Farmacologia da Inflamação e do Comportamento, Faculdade de Ciências Farmacêuticas, Universidade Federal do Pará (UFPA), Belém, Brazil
| | - Alana Miranda Pinheiro
- Laboratório de Farmacologia da Inflamação e do Comportamento, Faculdade de Ciências Farmacêuticas, Universidade Federal do Pará (UFPA), Belém, Brazil
| | - Ivaldo Jesus Almeida Belém-Filho
- Laboratório de Farmacologia da Inflamação e do Comportamento, Faculdade de Ciências Farmacêuticas, Universidade Federal do Pará (UFPA), Belém, Brazil
| | - Luanna Melo Pereira Fernandes
- Laboratório de Farmacologia da Inflamação e do Comportamento, Faculdade de Ciências Farmacêuticas, Universidade Federal do Pará (UFPA), Belém, Brazil
| | - Sabrina Carvalho Cartágenes
- Laboratório de Farmacologia da Inflamação e do Comportamento, Faculdade de Ciências Farmacêuticas, Universidade Federal do Pará (UFPA), Belém, Brazil
| | - Paula Cardoso Ribera
- Laboratório de Farmacologia da Inflamação e do Comportamento, Faculdade de Ciências Farmacêuticas, Universidade Federal do Pará (UFPA), Belém, Brazil
| | - Enéas Andrade Fontes-Júnior
- Laboratório de Farmacologia da Inflamação e do Comportamento, Faculdade de Ciências Farmacêuticas, Universidade Federal do Pará (UFPA), Belém, Brazil
| | | | - Marta Chagas Monteiro
- Laboratório de Microbiologia e Imunologia Clinica, Faculdade de Ciências Farmacêuticas, UFPA, Belém, Brazil
| | - Marcelo Oliveira Lima
- Laboratório de Toxicologia, Seção de Meio Ambiente, Instituto Evandro Chagas, Belém, Pará, Brazil
| | - Cristiane Socorro Ferraz Maia
- Laboratório de Farmacologia da Inflamação e do Comportamento, Faculdade de Ciências Farmacêuticas, Universidade Federal do Pará (UFPA), Belém, Brazil.
| |
Collapse
|
13
|
Belém-Filho IJA, Ribera PC, Nascimento AL, Gomes ARQ, Lima RR, Crespo-Lopez ME, Monteiro MC, Fontes-Júnior EA, Lima MO, Maia CSF. Low doses of methylmercury intoxication solely or associated to ethanol binge drinking induce psychiatric-like disorders in adolescent female rats. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2018; 60:184-194. [PMID: 29734102 DOI: 10.1016/j.etap.2018.04.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 04/24/2018] [Accepted: 04/27/2018] [Indexed: 06/08/2023]
Abstract
Methylmercury (MeHg) is an environmental contaminant that provokes damage to developing brain. Simultaneously, the consumption of ethanol among adolescents has increased. Evidence concerning the effects of MeHg low doses per se or associated with ethanol during adolescence are scarce. Thus, we investigate behavioral disorders resulted from exposure to MeHg low doses and co-intoxicated with ethanol in adolescent rats. Wistar rats received chronic exposure to low doses of MeHg (40 μg/kg/day for 5 weeks) and/or ethanol binge drinking (3 g/kg/day at 3 days per week for 5 weeks). Animals were submitted to behavioral assays to assess emotionality and cognitive function. Total mercury content was evaluated in the brain and hair. Oxidative parameters were analyzed in blood samples. MeHg at low doses or associated to ethanol binge drinking produced psychiatric-like disorders and cognitive impairment. Peripherally, MeHg altered oxidative parameters when associated to ethanol. Ethanol administration reduced brain mercury deposit. We proposed that ethanol reduces the necessity of mercury tissue levels to display psychiatric-like disorders/cognitive impairment.
Collapse
Affiliation(s)
| | - Paula Cardoso Ribera
- Laboratório de Farmacologia da Inflamação e Comportamento, Universidade Federal do Pará, Belém, Pará, Brazil
| | - Aline Lima Nascimento
- Laboratório de Farmacologia da Inflamação e Comportamento, Universidade Federal do Pará, Belém, Pará, Brazil
| | | | - Rafael Rodrigues Lima
- Laboratório de Biologia Funcional e Estrutural, Universidade Federal do Pará, Belém, Pará, Brazil
| | - Maria Elena Crespo-Lopez
- Laboratório de Ensaios In Vitro, Imunologia e Microbiologia, Universidade Federal do Pará, Belém, Pará, Brazil
| | - Marta Chagas Monteiro
- Laboratório de Farmacologia Molecular, Universidade Federal do Pará, Belém, Pará, Brazil
| | - Enéas Andrade Fontes-Júnior
- Laboratório de Farmacologia da Inflamação e Comportamento, Universidade Federal do Pará, Belém, Pará, Brazil
| | - Marcelo Oliveira Lima
- Laboratório de Toxicologia, Seção de Meio Ambiente, Instituto Evandro Chagas, Belém, Pará, Brazil
| | | |
Collapse
|
14
|
Sakamoto M, Chan HM, Domingo JL, Koriyama C, Murata K. Placental transfer and levels of mercury, selenium, vitamin E, and docosahexaenoic acid in maternal and umbilical cord blood. ENVIRONMENT INTERNATIONAL 2018; 111:309-315. [PMID: 29150340 DOI: 10.1016/j.envint.2017.11.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 10/27/2017] [Accepted: 11/02/2017] [Indexed: 06/07/2023]
Abstract
Methylmercury (MeHg) is a neurotoxicant known to affect the developing fetal brain as a sensitive target organ. As most mercury (Hg) in blood is MeHg, total mercury (THg) levels in blood are used to estimate the body burden of MeHg. The nutrients selenium (Se), vitamin E, and docosahexaenoic acid (DHA) are protective against MeHg toxicity. We compared maternal and cord blood concentrations of biochemical substances, THg and Se, vitamin E, DHA, and other elements, fatty acids, and amino acids in 54 Japanese mother-newborn pairs to elucidate the fetal risk of MeHg toxicity. Cord blood had higher hematocrit and amino acid values and lower concentrations of lipid components, including fatty acids compared with maternal blood. THg levels in cord blood (7.26ng/g) were 1.9 times higher than levels in maternal blood (3.79ng/g). Se concentrations in cord blood (176ng/g) were slightly higher than concentrations in maternal blood (156ng/g). Levels of vitamin E (0.31mg/dL) and DHA (58.8μg/mL) in cord blood were much lower than levels in maternal blood (1.38mg/dL and 147μg/mL, respectively). The ratios of Se/THg, vitamin E/THg, and DHA/THg in cord blood were lower than ratios in maternal blood. These results suggest that fetuses are at higher risk to MeHg toxicity.
Collapse
Affiliation(s)
- Mineshi Sakamoto
- Environmental Health Section, Department of Environmental Science and Epidemiology, National Institute for Minamata Disease, Minamata, Japan; Department of Epidemiology and Preventive Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
| | - Hing Man Chan
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - José L Domingo
- Laboratory of Toxicology and Environmental Health, School of Medicine, IISPV, Universitat "Rovira i Virgili", Reus, Spain
| | - Chihaya Koriyama
- Department of Epidemiology and Preventive Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Katsuyuki Murata
- Department of Environmental Health Sciences, Akita University Graduate School of Medicine, Akita, Japan
| |
Collapse
|
15
|
Oxidative Biochemistry Disbalance and Changes on Proteomic Profile in Salivary Glands of Rats Induced by Chronic Exposure to Methylmercury. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:5653291. [PMID: 28811865 PMCID: PMC5546058 DOI: 10.1155/2017/5653291] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 06/07/2017] [Accepted: 06/13/2017] [Indexed: 12/22/2022]
Abstract
Methylmercury (MeHg) is one of the most toxic mercury species, which can cause many systemic damages, but little is known about its effect in the salivary glands. This study aimed to analyze the mercury levels, oxidative stress, and proteomic profile in parotid, submandibular, and sublingual salivary glands of rats, after chronic MeHg intoxication. Two groups of twenty male Wistar rats (90 days of age) were used on the experiment. MeHg group was intoxicated by intragastric gavage with MeHg at a dose of 0.04 mg/kg/day for 60 days, while the control group received only oil. After the period of intoxication, the glands were collected for evaluation of total mercury levels, proteomic profile, and oxidative balance by analyzing the antioxidant capacity against peroxyl radicals (ACAP), lipid peroxidation (LPO), and nitrite levels. Our results have showed that mercury levels were significant in all three glands compared to the respective control. It also showed lower levels of ACAP, as well as higher LPO and nitrite levels. The proteomic profile presented impairments on structural components of cytoskeleton, metabolic pathways, and oxidative biochemistry. Thus, the exposure to MeHg was able to generate oxidative stress that could be associated with changes in the proteomic profile of salivary glands.
Collapse
|
16
|
Shen AN, Cummings C, Hoffman D, Pope D, Arnold M, Newland MC. Aging, motor function, and sensitivity to calcium channel blockers: An investigation using chronic methylmercury exposure. Behav Brain Res 2016; 315:103-14. [PMID: 27481695 DOI: 10.1016/j.bbr.2016.07.049] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 07/25/2016] [Accepted: 07/29/2016] [Indexed: 11/17/2022]
Abstract
Methylmercury (MeHg) neurotoxicity is thought to be mediated, in part, by dysregulation of calcium (Ca(2+)) homeostasis, a mechanism that may also slowly and progressively degrade neuronal function during normal aging. Longitudinal studies of MeHg exposure provide a powerful approach to studying neural and behavioral mechanisms by which both MeHg toxicity and aging affect motor function. Wheel-running and rotarod performance were assessed in two age groups of BALB/c mice chronically exposed to 0 or 1.2mg/kg/day MeHg and 0 or 20mg/kg/day nimodipine, a 1,4-dihyrdopyridine L-type calcium channel blocker (CCB), for approximately 8.5 months. Adults began exposure on postnatal day (PND) 72 and retired breeders on PND 296. A log-survivor bout analysis partitioned wheel-running into bouts that identified motor (within-bout rates) and motivational (bout-initiation rates) influences. Retired breeders ran farther, because of a higher bout-initiation rates, but performed more poorly on the rotarod than younger adults, a difference unaffected by nimodipine. MeHg produced relatively age-independent deficits in wheel-running and rotarod performance, whereas nimodipine afforded greater protection to adult mice than to retired breeders. Rotarod performance and within-bout response rate were more sensitive to and more reliable predictors of MeHg toxicity than bout-initiation rate, which was least affected by MeHg exposure. Thus the motivation to run was unimpaired as the ability to do so declined. While chronic MeHg exposure produced functionally similar behavior deficits between age groups, the age-dependent neuroprotection by nimodipine supports the notion that underlying neurobiological systems mediated by Ca(2+) signaling, are differentially affected in older adults.
Collapse
Affiliation(s)
| | - Craig Cummings
- Department of Psychology, University of Alabama, United States
| | - Daniel Hoffman
- Department of Psychology, Indiana University Southeast, United States
| | - Derek Pope
- Virginia Tech Carilion Research Institute's Addiction Recovery Research Center, United States
| | - Megan Arnold
- Department of Psychology, Behavioral Toxicology Lab, Auburn University, United States
| | - M Christopher Newland
- Department of Psychology, Behavioral Toxicology Lab, Auburn University, United States.
| |
Collapse
|
17
|
Sahin D, Erdolu CO, Karadenizli S, Kara A, Bayrak G, Beyaz S, Demir B, Ates N. Effects of gestational and lactational exposure to low dose mercury chloride (HgCl2) on behaviour, learning and hearing thresholds in WAG/Rij rats. EXCLI JOURNAL 2016; 15:391-402. [PMID: 27540351 PMCID: PMC4983802 DOI: 10.17179/excli2016-315] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 06/05/2016] [Indexed: 01/18/2023]
Abstract
We investigated the effects of inorganic mercury exposure during gestational/lactational periods on the behaviour, learning and hearing functions in a total of 32, 5-week-old and 5-month-old WAG/Rij rats (equally divided into 4 groups as 5-week and 5-month control mercury exposure groups). We evaluated the rats in terms of locomotor activity (LA), the Morris-water-maze (MWM) test and the passive avoidance (PA) test to quantify learning and memory performance; we used distortion product otoacoustic emission (DPOAE) tests to evaluate hearing ability. There were no significant differences between the 5-week-old rat groups in LA, and we detected a significant difference (p < 0.05) in the HgCl2-treated group in PA, MWM and DPOAE tests compared with the control group. The HgCl2-treated 5-week-old group exhibited worse emotional memory performance in PA, worse spatial learning and memory performances in MWM. There were no significant differences between the groups of 5-month-old rats in LA, MWM or PA. However, the DPOAE tests worsened in the mid- and high-frequency hearing thresholds. The HgCl2-treated 5-month-old group exhibited the most hearing loss of all groups. Our results convey that mercury exposure in young rats may worsen learning and memory performances as well as hearing at high-frequency levels. While there was no statistically significant difference in the behavior and learning tests in adult rats, the DPOAE test produced poorer results. Early detection of effects of mercury exposure provides medicals team with an opportunity to determinate treatment regimens and mitigate ototoxicity. DPOAE test can be used in clinical and experimental research investigating heavy metal ototoxicity.
Collapse
Affiliation(s)
- Deniz Sahin
- Kocaeli University / Medical Faculty, Physiology, Kocaeli, Turkey
| | | | | | - Ahmet Kara
- Sakarya University Training and Research Hospital, Otorhinolaryngology Department, Sakarya,Turkey
| | - Gunce Bayrak
- Kocaeli University / Medical Faculty, Kocaeli, Turkey
| | - Sumeyye Beyaz
- Kocaeli University / Medical Faculty, Kocaeli, Turkey
| | - Buse Demir
- Kocaeli University / Medical Faculty, Kocaeli, Turkey
| | - Nurbay Ates
- Kocaeli University / Medical Faculty, Physiology, Kocaeli, Turkey
| |
Collapse
|
18
|
Adedara IA, Rosemberg DB, Souza DO, Kamdem JP, Farombi EO, Aschner M, Rocha JBT. Biochemical and behavioral deficits in the lobster cockroach Nauphoeta cinerea model of methylmercury exposure. Toxicol Res (Camb) 2015. [DOI: 10.1039/c4tx00231h] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Methylmercury (MeHg) is well-known for its neurodevelopmental effects both in animals and in humans.
Collapse
Affiliation(s)
- Isaac A. Adedara
- Departamento de Bioquímica e Biologia Molecular
- CCNE
- Universidade Federal de Santa Maria
- 97105-900 Santa Maria
- Brazil
| | - Denis B. Rosemberg
- Departamento de Bioquímica e Biologia Molecular
- CCNE
- Universidade Federal de Santa Maria
- 97105-900 Santa Maria
- Brazil
| | - Diogo O. Souza
- Departamento de Bioquímica
- Instituto de Ciências Básicas da Saúde
- Universidade Federal do Rio Grande do Sul
- 90035-003 Porto Alegre
- Brazil
| | - Jean P. Kamdem
- Departamento de Bioquímica e Biologia Molecular
- CCNE
- Universidade Federal de Santa Maria
- 97105-900 Santa Maria
- Brazil
| | - Ebenezer O. Farombi
- Drug Metabolism and Toxicology Research Laboratories
- Department of Biochemistry
- College of Medicine
- University of Ibadan
- Ibadan
| | - Michael Aschner
- Department of Molecular Pharmacology
- Albert Einstein College of Medicine Forchheimer 209
- Bronx
- USA
| | - Joao B. T. Rocha
- Departamento de Bioquímica e Biologia Molecular
- CCNE
- Universidade Federal de Santa Maria
- 97105-900 Santa Maria
- Brazil
| |
Collapse
|
19
|
Bisen-Hersh EB, Farina M, Barbosa F, Rocha JBT, Aschner M. Behavioral effects of developmental methylmercury drinking water exposure in rodents. J Trace Elem Med Biol 2014; 28:117-124. [PMID: 24210169 PMCID: PMC3979511 DOI: 10.1016/j.jtemb.2013.09.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 09/19/2013] [Accepted: 09/19/2013] [Indexed: 10/26/2022]
Abstract
Early methylmercury (MeHg) exposure can have long-lasting consequences likely arising from impaired developmental processes, the outcome of which has been exposed in several longitudinal studies of affected populations. Given the large number of newborns at an increased risk of learning disabilities associated with in utero MeHg exposure, it is important to study neurobehavioral alterations using ecologically valid and physiologically relevant models. This review highlights the benefits of using the MeHg drinking water exposure paradigm and outlines behavioral outcomes arising from this procedure in rodents. Combination treatments that exacerbate or ameliorate MeHg-induced effects, and possible molecular mechanisms underlying behavioral impairment are also discussed.
Collapse
Affiliation(s)
- Emily B Bisen-Hersh
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Marcelo Farina
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Fernando Barbosa
- Department of Clinical, Toxicological and Bromatological Analyses, Faculty of Pharmaceutical Sciences of Ribeirão Preto, São Paulo, Brazil
| | - Joao B T Rocha
- Departamento de Química, Universidade Federal de Santa Maria, Santa Maria, Rio Grande do Sul, Brazil
| | - Michael Aschner
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Pharmacology, The Kennedy Center for Research on Human Development, and The Center for Molecular Toxicology, Vanderbilt University Medical Center, Nashville, TN, USA
| |
Collapse
|
20
|
Kong HK, Wong MH, Chan HM, Lo SCL. Chronic exposure of adult rats to low doses of methylmercury induced a state of metabolic deficit in the somatosensory cortex. J Proteome Res 2013; 12:5233-45. [PMID: 23984759 DOI: 10.1021/pr400356v] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Because of the ever-increasing bioaccumulation of methylmercury (MeHg) in the marine food chain, human consumers are exposed to low doses of MeHg continually through seafood consumption. Epidemiological studies strongly suggest that chronic prenatal exposure to nanomolar of MeHg has immense negative impacts on neurological development in neonates. However, effects of chronic exposure to low doses (CELDs) of MeHg in adult brains on a molecular level are unknown. The current study aims to investigate the molecular effects of CELD of MeHg on adult somatosensory cortex in a rat model using proteomic techniques. Young adult rats were fed with a low dose of MeHg (40 μg/kg body weight/day) for a maximum of 12 weeks. Whole proteome expression of the somatosensory cortex (S1 area) of normal rats and those with CELD to MeHg were compared. Levels of MeHg, total calcium, adenosine triphosphate (ATP), and pyruvate were also measured. Comparative proteomic studies of the somatosensory cortexes revealed that 94 proteins involved in the various metabolic processes (including carbohydrate metabolism, generation of precursors for essential metabolites, energy, proteins, cellular components for morphogenesis, and neurotransmission) were down-regulated. Consequently, levels of important end products of active metabolism including ATP, pyruvate, and total calcium were also found to be significantly reduced concomitantly. Our results showed that CELD of MeHg induced a state of metabolic deficit in the somatosensory cortex of adult rats.
Collapse
Affiliation(s)
- Hang-Kin Kong
- Food Safety and Technology Research Centre, The Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University , Room Y810, Lee Shau Kee Building (Block Y), Hung Hom, Hong Kong, China
| | | | | | | |
Collapse
|
21
|
Hassauer M, Kaiser E, Schneider K, Schuhmacher‐Wolz U. Collate the literature on toxicity data on mercury in experimental animals and humans (Part I – Data on organic mercury). ACTA ACUST UNITED AC 2012. [DOI: 10.2903/sp.efsa.2012.en-297] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Martin Hassauer
- Forschungs‐ und Beratungsinstitut Gefahrstoffe GmbH (FoBiG) Freiburg Germany
| | - Eva Kaiser
- Forschungs‐ und Beratungsinstitut Gefahrstoffe GmbH (FoBiG) Freiburg Germany
| | - Klaus Schneider
- Forschungs‐ und Beratungsinstitut Gefahrstoffe GmbH (FoBiG) Freiburg Germany
| | | |
Collapse
|
22
|
Scientific Opinion on the risk for public health related to the presence of mercury and methylmercury in food. EFSA J 2012. [DOI: 10.2903/j.efsa.2012.2985] [Citation(s) in RCA: 276] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
|
23
|
Kaur P, Aschner M, Syversen T. Biochemical factors modulating cellular neurotoxicity of methylmercury. J Toxicol 2011; 2011:721987. [PMID: 21941541 PMCID: PMC3177097 DOI: 10.1155/2011/721987] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2011] [Revised: 06/28/2011] [Accepted: 07/13/2011] [Indexed: 11/30/2022] Open
Abstract
Methylmercury (MeHg), an environmental toxicant primarily found in fish and seafood, poses a dilemma to both consumers and regulatory authorities, given the nutritional benefits of fish consumption versus the possible adverse neurological damage. Several studies have shown that MeHg toxicity is influenced by a number of biochemical factors, such as glutathione (GSH), fatty acids, vitamins, and essential elements, but the cellular mechanisms underlying these complex interactions have not yet been fully elucidated. The objective of this paper is to outline the cellular response to dietary nutrients, as well as to describe the neurotoxic exposures to MeHg. In order to determine the cellular mechanism(s) of toxicity, the effect of pretreatment with biochemical factors (e.g., N-acetyl cysteine, (NAC); diethyl maleate, (DEM); docosahexaenoic acid, (DHA); selenomethionine, SeM; Trolox) and MeHg treatment on intercellular antioxidant status, MeHg content, and other endpoints was evaluated. This paper emphasizes that the protection against oxidative stress offered by these biochemical factors is among one of the major mechanisms responsible for conferring neuroprotection. It is therefore critical to ascertain the cellular mechanisms associated with various dietary nutrients as well as to determine the potential effects of neurotoxic exposures for accurately assessing the risks and benefits associated with fish consumption.
Collapse
Affiliation(s)
- Parvinder Kaur
- Department of Neuroscience, Norwegian University of Science and Technology, 7489 Trondheim, Norway
| | - Michael Aschner
- Departments of Pediatrics and Pharmacology and The Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, B-3307 Medical Center North, 1162 21st Avenue, Nashville, TN 37232-2495, USA
| | - Tore Syversen
- Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology, Olav Kyrres Gate 3, 7489 Trondheim, Norway
| |
Collapse
|
24
|
Mameli M, Lippolis V, Caltagirone C, Capelo JL, Faza ON, Lodeiro C. Hg2+ Detection by New Anthracene Pendant-Arm Derivatives of Mixed N/S- and N/S/O-Donor Macrocycles: Fluorescence, Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry and Density Functional Theory Studies. Inorg Chem 2010; 49:8276-86. [DOI: 10.1021/ic1007439] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Marta Mameli
- Dipartimento di Chimica Inorganica ed Analitica, Università degli Studi di Cagliari, S.S. 554 Bivio per Sestu, 09042 Monserrato, Italy
| | - Vito Lippolis
- Dipartimento di Chimica Inorganica ed Analitica, Università degli Studi di Cagliari, S.S. 554 Bivio per Sestu, 09042 Monserrato, Italy
| | - Claudia Caltagirone
- Dipartimento di Chimica Inorganica ed Analitica, Università degli Studi di Cagliari, S.S. 554 Bivio per Sestu, 09042 Monserrato, Italy
| | - José Luis Capelo
- Grupo BIOSCOPE, Departamento de Química-Física, Facultad de Ciencias de Ourense, Universidad de Vigo, E-32004 Ourense, Spain
- REQUIMTE-CQFB, Departamento de Química, FCT, Universidade Nova de Lisboa, Monte de Caparica 2829-516, Portugal
| | - Olalla Nieto Faza
- Departamento de Química Orgánica, Facultade de Ciencias de Ourense, Universidade de Vigo, E-32004 Ourense, Spain
| | - Carlos Lodeiro
- Grupo BIOSCOPE, Departamento de Química-Física, Facultad de Ciencias de Ourense, Universidad de Vigo, E-32004 Ourense, Spain
- REQUIMTE-CQFB, Departamento de Química, FCT, Universidade Nova de Lisboa, Monte de Caparica 2829-516, Portugal
| |
Collapse
|
25
|
Huang L, Peng Y, Li Z, Wei Z, Hughes DL, Zeng X, Luo Q, Liu X. Two Hg(II) complexes with a capped trigonal prismatic geometry derived from multidentate macrocyclic ligands containing N and S donors, with coordinated anions. Inorganica Chim Acta 2010. [DOI: 10.1016/j.ica.2010.03.066] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
26
|
Ishitobi H, Stern S, Thurston SW, Zareba G, Langdon M, Gelein R, Weiss B. Organic and inorganic mercury in neonatal rat brain after prenatal exposure to methylmercury and mercury vapor. ENVIRONMENTAL HEALTH PERSPECTIVES 2010; 118:242-8. [PMID: 20123608 PMCID: PMC2831924 DOI: 10.1289/ehp.0900956] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Accepted: 09/29/2009] [Indexed: 05/04/2023]
Abstract
BACKGROUND Many populations are exposed to multiple species of mercury (Hg), predominantly organic Hg as methylmercury (MeHg) from fish, and inorganic Hg as Hg vapor from dental amalgams. Most of our knowledge of the neurotoxicity of Hg is based on research devoted to studying only one form at a time, mostly MeHg. OBJECTIVES In this study we investigated the effects of prenatal exposure to MeHg and Hg vapor on Hg concentrations in the brain of neonatal rats. METHODS Female Long-Evans hooded rats were exposed to MeHg (0, 3, 6, or 9 ppm as drinking solution), Hg vapor (0, 300, or 1,000 microg/m3 for 2 hr/day), or the combination of both, from 30 days before breeding through gestational day 18. On postnatal day 4, whole brains were taken from one male and one female from each of four litters in each treatment group to assess organic and inorganic Hg in the brain by cold vapor atomic absorption spectrometry. RESULTS Statistical analysis using linear mixed effects models showed that MeHg dose was the primary determinant of both organic and inorganic brain Hg levels. For both outcomes, we also found significant interactions between MeHg and Hg vapor exposure. These interactions were driven by the fact that among animals not exposed to MeHg, animals exposed to Hg vapor had significantly greater organic and inorganic brain Hg levels than did unexposed animals. CONCLUSION This interaction, heretofore not reported, suggests that coexposure to MeHg and Hg vapor at levels relevant to human exposure might elevate neurotoxic risks.
Collapse
Affiliation(s)
| | | | - Sally W. Thurston
- Department of Biostatistics and Computational Biology, School of Medicine and Dentistry, University of Rochester, Rochester, New York, USA
| | | | | | | | - Bernard Weiss
- Department of Environmental Medicine and
- Address correspondence to B. Weiss, Department of Environmental Medicine, Box EHSC, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642 USA. Telephone: (585) 275-1736. Fax: (585) 256-2591. E-mail:
| |
Collapse
|
27
|
Dietary selenium protects against selected signs of aging and methylmercury exposure. Neurotoxicology 2010; 31:169-79. [PMID: 20079371 DOI: 10.1016/j.neuro.2010.01.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Revised: 12/24/2009] [Accepted: 01/06/2010] [Indexed: 01/01/2023]
Abstract
Acute or short-term exposure to high doses of methylmercury (MeHg) causes a well-characterized syndrome that includes sensory and motor deficits. The environmental threat from MeHg, however, comes from chronic, low-level exposure, the consequences of which are poorly understood. Selenium (Se), an essential nutrient, both increases deposition of mercury (Hg) in neurons and mitigates some of MeHg's neurotoxicity in the short term, but it is unclear whether this deposition produces long-term adverse consequences. To investigate these issues, adult Long-Evans rats were fed a diet containing 0.06 or 0.6 ppm of Se as sodium selenite. After 100 days on these diets, the subjects began consuming 0.0, 0.5, 5.0, or 15 ppm of Hg as methylmercuric chloride in their drinking water for 16 months. Somatosensory sensitivity, grip strength, hindlimb cross (clasping reflex), flexion, and voluntary wheel-running in overnight sessions were among the measures examined. MeHg caused a dose- and time-dependent impairment in all measures. No effects appeared in rats consuming 0 or 0.5 ppm of Hg. Somatosensory function, grip strength, and flexion were among the earliest signs of exposure. Selenium significantly delayed or blunted MeHg's effects. Selenium also increased running in unexposed animals as they aged, a novel finding that may have important clinical implications. Nerve pathology studies revealed axonal atrophy or mild degeneration in peripheral nerve fibers, which is consistent with abnormal sensorimotor function in chronic MeHg neurotoxicity. Lidocaine challenge reproduced the somatosensory deficits but not hindlimb cross or flexion. Together, these results quantify the neurotoxicity of long-term MeHg exposure, support the safety and efficacy of Se in ameliorating MeHg's neurotoxicity, and demonstrate the potential benefits of Se during aging.
Collapse
|
28
|
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.
Collapse
Affiliation(s)
- Sameera Dasari
- Department of Pharmacology and Toxicology, B307A Life Science Building, Michigan State University, East Lansing, MI 48824-1317, USA
| | | |
Collapse
|
29
|
Folven KI, Glover CN, Malde MK, Lundebye AK. Does selenium modify neurobehavioural impacts of developmental methylmercury exposure in mice? ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2009; 28:111-119. [PMID: 21783990 DOI: 10.1016/j.etap.2009.03.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2009] [Revised: 03/03/2009] [Accepted: 03/04/2009] [Indexed: 05/31/2023]
Abstract
There is controversy as to whether low-level chronic exposure to methylmercury (MeHg) through maternal fish consumption may cause subtle effects in the developing child, owing in part to the potential ameliorating effects of beneficial seafood nutrients. The aim of the present investigation was to assess the ameliorating potential of selenium (Se; as the naturally occurring methionine complex) on the neurobehavioural toxicity of foodborne MeHg (as the naturally occurring cysteinate) in prenatally exposed mice. Pups from dams exposed to a diet containing 3mg/kg of MeHg fed throughout gestation showed delayed fur development and impaired performance in a motor function assessment. These effects were not apparent in pups born to dams concurrently exposed to Se (at 1.3mg/kg). These results, using natural dietary forms of the elements administered through the relevant exposure pathway, suggest only minor impacts of MeHgCys on neurobehaviour, and possible amelioration of these effects by Se.
Collapse
Affiliation(s)
- Kristin I Folven
- National Institute of Nutrition and Seafood Research (NIFES), Bergen, Norway
| | | | | | | |
Collapse
|
30
|
Ralston NV, Ralston CR, Blackwell JL, Raymond LJ. Dietary and tissue selenium in relation to methylmercury toxicity. Neurotoxicology 2008; 29:802-11. [DOI: 10.1016/j.neuro.2008.07.007] [Citation(s) in RCA: 198] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Revised: 07/22/2008] [Accepted: 07/22/2008] [Indexed: 10/21/2022]
|
31
|
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.
Collapse
Affiliation(s)
- M Christopher Newland
- Department of Psychology, 226 Thach Hall, Auburn University, Auburn, AL 36849-5214, USA.
| | | | | |
Collapse
|
32
|
Rice DC. Overview of modifiers of methylmercury neurotoxicity: chemicals, nutrients, and the social environment. Neurotoxicology 2008; 29:761-6. [PMID: 18722469 DOI: 10.1016/j.neuro.2008.07.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Revised: 06/26/2008] [Accepted: 07/07/2008] [Indexed: 10/21/2022]
Abstract
It has been known for decades that methylmercury is a potent neurotoxicant, and that the developing brain is more susceptible to impairment as a result of methylmercury exposure than is the adult. Exposure to methylmercury is exclusively through consumption of fish and marine mammals. In recent years, the potential for protection against methylmercury toxicity by nutrients present in fish, particularly omega-3 fatty acids and selenium, has been explored in both epidemiological and experimental studies. There is evidence from several studies that fish consumption per se and methylmercury body burden act in opposition with regard to neuropsychological outcomes, whereas the evidence for a protective effect of specific nutrients is contradictory in both epidemiological and experimental studies published to date. The potential for methylmercury to interact with other chemicals present in marine food, particularly PCBs, has been explored in both animal models and human studies. Results may be both exposure- and endpoint-dependent. The Seychelles Islands study has explored the potential for the social environment to modify the effects of developmental methylmercury exposure. An understanding of the interactions of the multiple factors that determine the final behavioral outcome of exposure to methylmercury is crucial to risk assessment and risk management decisions.
Collapse
Affiliation(s)
- Deborah C Rice
- Maine Center for Disease Control and Prevention, Augusta, ME 04333, United States.
| |
Collapse
|
33
|
Neonatal co-exposure to low doses of an ortho-PCB (PCB 153) and methyl mercury exacerbate defective developmental neurobehavior in mice. Toxicology 2008; 244:157-65. [DOI: 10.1016/j.tox.2007.11.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2007] [Revised: 11/08/2007] [Accepted: 11/09/2007] [Indexed: 11/23/2022]
|
34
|
Fischer C, Fredriksson A, Eriksson P. Coexposure of neonatal mice to a flame retardant PBDE 99 (2,2',4,4',5-pentabromodiphenyl ether) and methyl mercury enhances developmental neurotoxic defects. Toxicol Sci 2007; 101:275-85. [PMID: 17982161 DOI: 10.1093/toxsci/kfm271] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Epidemiological studies indicate that exposure to environmental pollutants during early human development can have deleterious effects on cognitive development. The interaction between environmental pollutants is suggested as one reason for the observed defective neurological development in children from the Faeroe Islands as compared to children from the Seychelles. We have previously seen in mice that polychlorinated biphenyls (PCBs) can interact together with methyl mercury (MeHg), as well as PCB together with polybrominated diphenyl ether (PBDE 99) to exacerbate developmental neurotoxic effects when present during a critical period of neonatal brain development. PBDEs are a new class of global environmental contaminants. The present study shows that neonatal coexposure to PBDE 99 (0.8 mg/kg body weight) and MeHg (0.4 or 4.0 mg/kg body weight) can exacerbate developmental neurotoxic effects. These effects are manifested as disrupted spontaneous behavior, reduced habituation, and impaired learning/memory abilities. This is seen in the low dose range, where the sole compounds do no give rise to developmental neurotoxic effects. The effects seen are more than just additive. Furthermore, a significant effect of interaction was seen on the cholinergic nicotinic receptors in the cerebral cortex and hippocampus. This suggests that a mechanism for the observed cognitive defects is via the cholinergic system. Furthermore, PBDE can interact with MeHg causing developmental neurotoxic effects similar to those we previously have observed between PCB 153 + MeHg and PCB 52 + PBDE 99. This is of vital importance, as the levels of PBDEs are increasing in mother's milk and in the environment generally.
Collapse
Affiliation(s)
- Celia Fischer
- Department of Environmental Toxicology, Uppsala University, Norbyvägen 18A, S-752 36 Uppsala, Sweden
| | | | | |
Collapse
|
35
|
Shichiri M, Takanezawa Y, Uchida K, Tamai H, Arai H. Protection of cerebellar granule cells by tocopherols and tocotrienols against methylmercury toxicity. Brain Res 2007; 1182:106-15. [DOI: 10.1016/j.brainres.2007.08.084] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Revised: 08/24/2007] [Accepted: 08/30/2007] [Indexed: 11/24/2022]
|
36
|
Kaur P, Schulz K, Aschner M, Syversen T. Role of Docosahexaenoic Acid in Modulating Methylmercury-Induced Neurotoxicity. Toxicol Sci 2007; 100:423-32. [PMID: 17728287 DOI: 10.1093/toxsci/kfm224] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The effect of docosahexaenoic acid (DHA) in modulating methylmercury (MeHg)-induced neurotoxicity was investigated in C6-glial and B35-neuronal cell lines. Gas chromatography measurements indicated increased DHA content in both the cell lines after 24 h supplementation. Mitochondrial activity evaluated by 3-(4, 5-dimethylthiazol-2-yl)-2, 5 diphenyltetrazolium bromide (MTT) reduction indicated that 10 microM MeHg treatment for 50 min led to a significant (p < 0.001) and similar decrease in MTT activity in both the cell lines. However, DHA pretreatment led to more pronounced depletion (p < 0.05) in the MTT activity in C6 cells as compared to B35 cells. The depletion of glutathione (GSH) content measured with the fluorescent indicator monochlorobimane was more apparent (p < 0.001) in C6 cells treated with DHA and MeHg. The amount of reactive oxygen species (ROS) detected with the fluorescent indicator -- chloromethyl derivative of dichloro dihydro fluorescein diacetate (CMH(2)DCFDA) -- indicated a fourfold increase in C6 cells (p < 0.001) as compared to twofold increase in B35 cells (p < 0.001) upon DHA and MeHg exposure. However, the cell-associated MeHg measurement using (14)C-labeled MeHg indicated a decrease (p < 0.05) in MeHg accumulation upon DHA exposure in both the cell lines. These findings provide experimental evidence that although pretreatment with DHA reduces cell-associated MeHg, it causes an increased ROS (p < 0.001) and GSH depletion (p < 0.05) in C6 cells.
Collapse
Affiliation(s)
- Parvinder Kaur
- Department of Neuroscience, Norwegian University of Science and Technology, N-7489, Trondheim, Norway.
| | | | | | | |
Collapse
|
37
|
Paletz EM, Day JJ, Craig-Schmidt MC, Newland MC. Spatial and visual discrimination reversals in adult and geriatric rats exposed during gestation to methylmercury and n-3 polyunsaturated fatty acids. Neurotoxicology 2007; 28:707-19. [PMID: 17582499 PMCID: PMC2180833 DOI: 10.1016/j.neuro.2007.05.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2006] [Revised: 04/11/2007] [Accepted: 05/01/2007] [Indexed: 11/16/2022]
Abstract
Fish contain essential long chain polyunsaturated fatty acids (PUFAs), particularly docosahexaenoic acid (DHA), an omega-3 (or n-3) PUFA, but are also the main source of exposure to methylmercury (MeHg), a potent developmental neurotoxicant. Since n-3 PUFAs support neural development and function, benefits deriving from a diet rich in n-3s have been hypothesized to protect against deleterious effects of gestational MeHg exposure. To determine whether protection occurs at the behavioral level, female Long-Evans rats were exposed, in utero, to 0, 0.5, or 5ppm of Hg as MeHg via drinking water, approximating exposures of 0, 40, and 400 microgHg/kg/day and producing 0, 0.29, and 5.50ppm of total Hg in the brains of siblings at birth. They also received pre- and postnatal exposure to one of two diets, both based on the AIN-93 semipurified formulation. A "fish-oil" diet was high in, and a "coconut-oil" diet was devoid of, DHA. Diets were approximately equal in alpha-linolenic acid and n-6 PUFAs. As adults, the rats were first assessed with a spatial discrimination reversal (SDR) procedure and later with a visual (nonspatial) discrimination reversal (VDR) procedure. MeHg increased the number of errors to criterion for both SDR and VDR during the first reversal, but effects were smaller or non-existent on the original discrimination and on later reversals. No such MeHg-related deficits were seen when the rats were retested on SDR after 2 years of age. These results are consistent with previous reports and hypotheses that gestational MeHg exposure produces perseverative responding. No interactions between diet and MeHg were found, suggesting that n-3 PUFAs do not guard against these behavioral effects. Brain Hg concentrations did not differ between the diets, either. In geriatric rats, failures to respond were less common and response latencies were shorter for rats fed the fish-oil diet, suggesting that exposure to a diet rich in n-3s may lessen the impact of age-related declines in response initiation.
Collapse
Affiliation(s)
- Elliott M Paletz
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI 53719, USA.
| | | | | | | |
Collapse
|
38
|
Newland MC, Reed MN, LeBlanc A, Donlin WD. Brain and blood mercury and selenium after chronic and developmental exposure to methylmercury. Neurotoxicology 2006; 27:710-20. [PMID: 16824603 DOI: 10.1016/j.neuro.2006.05.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2006] [Revised: 05/09/2006] [Accepted: 05/12/2006] [Indexed: 11/17/2022]
Abstract
Fish contain methylmercury and the potentially protective element, selenium. Blood and brain concentrations of these elements were determined in female rats after consuming AIN-93-based diets containing 0.06 or 0.6 ppm of selenium (Se) and drinking water containing 0, 0.5, or 5 ppm of mercury as methylmercury (MeHg) for 6 or 18 months. Brain and blood concentrations of mercury and selenium were also evaluated in neonates after gestational exposure. For adult rats in the high-Se, high-Hg condition, brain selenium content was 0.35 ppm and 1.8 ppm after 6 and 18 months, respectively, but for every other adult-onset condition, it was 0.1 ppm. Blood selenium varied less than two-fold despite a 10-fold difference in diet. After 6 months, mercury content in the brain showed a greater than 10-fold difference between the mercury groups, and interacted somewhat with dietary selenium. After 18 months, no mercury was detected in the brains of the 0.5 ppm groups, and their blood mercury also fell. For the 5.0 ppm groups, brain mercury increased slightly (low Se diet) or several-fold (high Se diet) over that seen at 6 months, and blood mercury also increased. Neonatal selenium concentrations were more labile than adults, and mercury in neonates was generally higher. All animals exposed to 5 ppm of mercury experienced a molar excess of mercury over selenium. Animals exposed to 0.5 ppm mercury showed a balance between mercury and selenium or a selenium excess, depending on the condition.
Collapse
|
39
|
Funchal C, Moretto MB, Vivian L, Zeni G, Rocha JBT, Pessoa-Pureur R. Diphenyl ditelluride- and methylmercury-induced hyperphosphorilation of the high molecular weight neurofilament subunit is prevented by organoselenium compounds in cerebral cortex of young rats. Toxicology 2006; 222:143-53. [PMID: 16564610 DOI: 10.1016/j.tox.2006.02.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Revised: 02/13/2006] [Accepted: 02/15/2006] [Indexed: 11/29/2022]
Abstract
Organotellurides are important intermediates in organic synthesis and, consequently, the occupational exposure to them is a constant risk for laboratory workers. These compounds can elicit many neurotoxic events in the central nervous system (CNS) that are associated with several neurological symptoms. In contrast, organoselenium compounds are considered to exert neuroprotective actions on such effects. Neurofilaments (NF) are important cytoskeletal proteins and phosphorylation/dephosphorylation of NF is important to stabilize the cytoskeleton. In this work we investigated the potential protective ability of the selenium compounds ebselen and diphenyl diselenide (PhSe)(2) against the effect of diphenyl ditelluride (PhTe)(2) and methylmercury (MeHg) on the total (phosphorylated plus nonphosphorylated) and phosphorylated immunocontent of the high molecular weight neurofilament subunit (NF-H) from slices of cerebral cortex of 17-day-old rats. We observed that 1muM MeHg induced hyperphosphorylation, increasing the total immunocontent of this subunit of the high-salt Triton insoluble NF-H. Otherwise, 15muM (PhTe)(2) induced hyperphosphorylation of the high-salt Triton insoluble NF-H without altering the total immunocontent of this protein into the cytoskeletal fraction. Concerning the selenium compounds, 15muM (PhSe)(2) and 5muM ebselen did not induce alteration per se on the in vitro phosphorylation of NF-H. In addition, (PhSe)(2) and ebselen at these concentrations, presented a protective effect against the action of (PhTe)(2) and MeHg, on the immunoreactivity of NF-H. Considering that hyperphosphorylation of NF-H is associated with neuronal dysfunction it is probable that the effects of (PhTe)(2) and MeHg could be related to the remarkable neurotoxicity of these organocalcogenides. Furthermore the neuroprotective action of selenium compounds against (PhTe)(2) and MeHg effects could be a promising route to be exploited for a possible treatment of calcogenides poisoning.
Collapse
Affiliation(s)
- C Funchal
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil
| | | | | | | | | | | |
Collapse
|
40
|
Diagnosis | Vesical calculus-induced obstructive dystocia. Lab Anim (NY) 2006. [DOI: 10.1038/laban0206-20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|