1
|
Amoussou N, Marengo M, Durieux EDH, Douny C, Scippo ML, Gobert S. Trace Elements and Fatty Acid Profile of Argyrosomus regius (Asso, 1801) from Mediterranean Aquaculture. Biol Trace Elem Res 2020; 196:618-628. [PMID: 31625052 DOI: 10.1007/s12011-019-01925-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 10/01/2019] [Indexed: 10/25/2022]
Abstract
Although Argyrosomus regius (Asso, 1801) counts among the most appreciated and increasingly consumed fish species in Europe, little information is available on its flesh quality. This research concerns both healthy aquatic resource diversification and good nutritional quality. It is the first study to evaluate the quality of A. regius flesh from Mediterranean aquaculture. It aims to assess the concentration of 19 trace elements and to determine the fatty acid profile of this fish farmed in the Mediterranean Sea and to discuss human exposure risks. The nutritional intake of oligoelements (selenium (Se), zinc (Zn), and chromium (Cr)) and the mean concentrations of contaminants (arsenic (As), barium (Ba), cadmium (Cd), lead (Pb), and tin (Sn)) in A. regius muscles are, respectively, above and below recommended regulatory standards set by the international legislation. Additionally, the low fat content in its muscle mass and its high level of docosahexaenoic acid (C22: 6 n-3; DHA) and, to a lesser extent, eicosapentaenoic acid (C20: 5 n-3; EPA) confers satisfying nutritional qualities. This study allowed to conclude that meager can be considered as a source of seafood with good nutritional qualities for human health.
Collapse
Affiliation(s)
- Nellya Amoussou
- Centre MARE, Laboratoire d'Océanologie, Université de Liège, Sart-Tilman, B6c, 4000, Liège, Belgium
| | - Michel Marengo
- Centre MARE, Laboratoire d'Océanologie, Université de Liège, Sart-Tilman, B6c, 4000, Liège, Belgium.
- STAtion de REcherche Sous-marines et Océanographiques (STARESO), 20260, Calvi, France.
- UMR 6134 CNRS-UCPP Sciences pour l'Environnement, Université de Corse Pascal Paoli, 20250, Corse, France.
| | - Eric Dominique Henry Durieux
- UMR 6134 CNRS-UCPP Sciences pour l'Environnement, Université de Corse Pascal Paoli, 20250, Corse, France
- UMS 3514 CNRS-UCPP Plateforme marine Stella Mare, Université de Corse Pascal Paoli, 20620, Biguglia, France
| | - Caroline Douny
- Faculté de Médecine vétérinaire, Laboratoire d'Analyse des Denrées Alimentaires, Université de Liège, Avenue de Cureghem 10, Bât B43B, Sart-Tilman, BE-4000, Liège, Belgium
| | - Marie-Louise Scippo
- Faculté de Médecine vétérinaire, Laboratoire d'Analyse des Denrées Alimentaires, Université de Liège, Avenue de Cureghem 10, Bât B43B, Sart-Tilman, BE-4000, Liège, Belgium
| | - Sylvie Gobert
- Centre MARE, Laboratoire d'Océanologie, Université de Liège, Sart-Tilman, B6c, 4000, Liège, Belgium
- STAtion de REcherche Sous-marines et Océanographiques (STARESO), 20260, Calvi, France
| |
Collapse
|
2
|
Canadian Arctic Contaminants and Their Effects on the Maternal Brain and Behaviour: A Scoping Review of the Animal Literature. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17030926. [PMID: 32024308 PMCID: PMC7038163 DOI: 10.3390/ijerph17030926] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 01/30/2020] [Accepted: 01/31/2020] [Indexed: 12/15/2022]
Abstract
Background: Environmental toxicants such as methylmercury, polychlorinated biphenyls, and organochlorine pesticides are potentially harmful pollutants present in contaminated food, soil, air, and water. Exposure to these ecologically relevant toxicants is prominent in Northern Canadian populations. Previous work focused on toxicant exposure during pregnancy as a threat to fetal neurodevelopment. However, little is known about the individual and combined effects of these toxicants on maternal health during pregnancy and post-partum. Methods: A scoping review was conducted to synthesize the current knowledge regarding individual and combined effects of methylmercury, polychlorinated biphenyls, and organochlorine pesticides on maternal behaviour and the maternal brain. Relevant studies were identified through the PubMed, Embase, and Toxline databases. Literature involving animal models and one human cohort were included in the review. Results: Research findings indicate that exposures to these environmental toxicants are associated with neurochemical changes in rodent models. Animal models provided the majority of information on toxicant-induced alterations in maternal care behaviours. Molecular and hormonal changes hypothesized to underlie these alterations were also addressed, although studies assessing toxicant co-exposure were limited. Conclusion: This review speaks to the limited knowledge regarding effects of these persistent organic pollutants on the maternal brain and related behavioural outcomes. Further research is required to better comprehend any such effects on maternal brain and behaviour, as maternal care is an important contributor to offspring neurodevelopment.
Collapse
|
3
|
Koli S, Prakash A, Choudhury S, Mandil R, Garg SK. Mercury affects uterine myogenic activity even without producing any apparent toxicity in rats: Involvement of calcium-signaling cascades. J Trace Elem Med Biol 2020; 57:40-47. [PMID: 31557574 DOI: 10.1016/j.jtemb.2019.09.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 08/31/2019] [Accepted: 09/11/2019] [Indexed: 10/26/2022]
Abstract
BACKGROUND Mercury is an established environmental toxicant reported to cause reproductive disorders in women, however, its direct action on myometrial activity is yet to be understood. Earlier we have reported the underlying mechanism of mercury-induced myometrial contractions following in vitro exposure; however, no such information on the effect of mercury on myometrial activity following in vivo exposure is available, therefore, the present study was undertaken. OBJECTIVE Present study was designed to evaluate the effect of mercury on myometrial activity following in vivo exposure of rats and unravel the possible underlying mechanism. METHODS Female Wistar rats were orally exposed to mercury (5, 50 and 500 μg/L in drinking water) for 28 days to investigate the toxicodynamics of mercuric chloride (HgCl2)-induced alterations in myometrial activity. Response of the isolated myometrial strips to different spasmogens was recorded using polyphysiograph. Blood and uterine calcium, mercury, iron and zinc levels were estimated by atomic absorption spectrophotometry. Blood biochemicals and serum hormonal profiles (estradiol, progesterone) were also determined. RESULTS No systemic toxicity of mercury was observed in any of the treatment groups (5, 50 and 500 μg/L) in terms of alterations in body weight, organ weights, blood biochemical parameters including hormonal profile. Interestingly, mercury at 5 μg/L concentration significantly increased the receptor-dependent (PGF2α-induced) and receptor-independent (CaCl2-induced and high K+-depolarizing solution-induced) myometrial contractions and it was coupled with corresponding increase in the uterine calcium levels. However, mercury at higher dose levels (50 and 500 μg/L) did not significantly alter the myometrial response. CONCLUSION Our results evidently suggest that mercury at low level (5 μg/L) produced detrimental effect on myometrial activity by altering calcium entry into the smooth muscle and/or the release of calcium from intracellular stores without causing any apparent systemic toxicity in rats.
Collapse
Affiliation(s)
- Swati Koli
- Experimental Pharmacology Laboratory, Department of Veterinary Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pt. Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, UP, India
| | - Atul Prakash
- Experimental Pharmacology Laboratory, Department of Veterinary Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pt. Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, UP, India
| | - Soumen Choudhury
- Experimental Pharmacology Laboratory, Department of Veterinary Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pt. Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, UP, India
| | - Rajesh Mandil
- Experimental Pharmacology Laboratory, Department of Veterinary Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pt. Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, UP, India
| | - Satish K Garg
- Experimental Pharmacology Laboratory, Department of Veterinary Pharmacology and Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pt. Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, UP, India.
| |
Collapse
|
4
|
Gagnon-Chauvin A, Bastien K, Saint-Amour D. Environmental toxic agents: The impact of heavy metals and organochlorides on brain development. HANDBOOK OF CLINICAL NEUROLOGY 2020; 173:423-442. [PMID: 32958188 DOI: 10.1016/b978-0-444-64150-2.00030-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Exposure to environmental toxicants can have deleterious effects on the development of physical, cognitive, and mental health. Extensive laboratory and clinical studies have demonstrated how the developing brain is uniquely sensitive to toxic agents. This chapter focuses on the main neurologic impairments linked to prenatal and postnatal exposure to lead, methylmercury, and polychlorinated biphenyls, three legacy environmental contaminants whose neurotoxic effects have been extensively studied with respect to cognitive and behavioral development. The main cognitive, emotion regulation, sensory, and motor impairments in association with these contaminants are briefly reviewed, including the underlying neural mechanisms such as neuropathologic damages, brain neurotransmission, and endocrine system alterations. The use of neuroimaging as a novel tool to better understand how the brain is affected by exposure to environmental contaminants is also discussed.
Collapse
Affiliation(s)
- Avril Gagnon-Chauvin
- Department of Psychology, Université du Québec à Montréal, Montréal, QC, Canada; Research Centre, Centre Hospitalier Universitaire Sainte-Justine, Université de Montréal, Montréal, QC, Canada
| | - Kevin Bastien
- Department of Psychology, Université du Québec à Montréal, Montréal, QC, Canada; Research Centre, Centre Hospitalier Universitaire Sainte-Justine, Université de Montréal, Montréal, QC, Canada
| | - Dave Saint-Amour
- Department of Psychology, Université du Québec à Montréal, Montréal, QC, Canada; Research Centre, Centre Hospitalier Universitaire Sainte-Justine, Université de Montréal, Montréal, QC, Canada.
| |
Collapse
|
5
|
Olguín N, Müller ML, Rodríguez-Farré E, Suñol C. Neurotransmitter amines and antioxidant agents in neuronal protection against methylmercury-induced cytotoxicity in primary cultures of mice cortical neurons. Neurotoxicology 2018; 69:278-287. [PMID: 30075218 DOI: 10.1016/j.neuro.2018.07.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 07/26/2018] [Accepted: 07/30/2018] [Indexed: 12/23/2022]
Abstract
Methylmercury (MeHg) is an environmental toxicant with detrimental effects on the developing brain and adult nervous system. The main mechanisms identified include oxidative stress, changes in intracellular calcium, mitochondrial changes, inhibition of glutamate uptake, of protein synthesis and disruption of microtubules. However, little is known about mechanisms of protection against MeHg neurotoxicity. We found that resveratrol (10 μM) and ascorbic acid (200 μM) protected MeHg-induced cell death in primary cultures of cortical neurons. In this work, we aimed at finding additional targets that may be related to MeHg mode of action in cell toxicity with special emphasis in cell protection. We wonder whether neurotransmitters may affect the MeHg effects on neuronal death. Our findings show that neurons exposed to low MeHg concentrations exhibit less mortality if co-exposed to 10 μM dopamine (DA). However, DA metabolites, HVA (homovanillic acid) and DOPAC (3,4-dihydroxyphenylacetic acid) are not responsible for such protection. Furthermore, both DA D1 and D2 receptors agonists showed a protective effect against MeHg toxicity. It is striking though that DA receptor antagonists SKF83566 (10 μM) and haloperidol (10 μM) did not inhibit DA protection against MeHg. In addition, the protective effect of 10 μM DA against MeHg-induced toxicity was not affected by additional organochlorine pollutants exposure. Our results also demonstrate that cells exposed to MeHg in presence of 100 μM acetylcholine (ACh), show an increase in cell mortality at the "threshold value" of 100 nM MeHg. Finally, norepinephrine (10 μM) and serotonin (20 μM) also had an effect on cell protection. Altogether, we propose to further investigate the additional mechanisms that may be playing an important role in MeHg-induced cytotoxicity.
Collapse
Affiliation(s)
- Nair Olguín
- Institut d'Investigacions Biomèdiques de Barcelona (IIBB), CSIC - IDIBAPS, CIBER de Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain
| | - Marie-Lena Müller
- Institut d'Investigacions Biomèdiques de Barcelona (IIBB), CSIC - IDIBAPS, CIBER de Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain
| | - Eduard Rodríguez-Farré
- Institut d'Investigacions Biomèdiques de Barcelona (IIBB), CSIC - IDIBAPS, CIBER de Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain
| | - Cristina Suñol
- Institut d'Investigacions Biomèdiques de Barcelona (IIBB), CSIC - IDIBAPS, CIBER de Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain.
| |
Collapse
|
6
|
Sampaio E, Lopes AR, Francisco S, Paula JR, Pimentel M, Maulvault AL, Repolho T, Grilo TF, Pousão-Ferreira P, Marques A, Rosa R. Ocean acidification dampens physiological stress response to warming and contamination in a commercially-important fish (Argyrosomus regius). THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 618:388-398. [PMID: 29132006 DOI: 10.1016/j.scitotenv.2017.11.059] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 11/05/2017] [Accepted: 11/06/2017] [Indexed: 06/07/2023]
Abstract
Increases in carbon dioxide (CO2) and other greenhouse gases emissions are changing ocean temperature and carbonate chemistry (warming and acidification, respectively). Moreover, the simultaneous occurrence of highly toxic and persistent contaminants, such as methylmercury, will play a key role in further shaping the ecophysiology of marine organisms. Despite recent studies reporting mostly additive interactions between contaminant and climate change effects, the consequences of multi-stressor exposure are still largely unknown. Here we disentangled how Argyrosomus regius physiology will be affected by future stressors, by analysing organ-dependent mercury (Hg) accumulation (gills, liver and muscle) within isolated/combined warming (ΔT=4°C) and acidification (ΔpCO2=1100μatm) scenarios, as well as direct deleterious effects and phenotypic stress response over multi-stressor contexts. After 30days of exposure, although no mortalities were observed in any treatments, Hg concentration was enhanced under warming conditions, especially in the liver. On the other hand, elevated CO2 decreased Hg accumulation and consistently elicited a dampening effect on warming and contamination-elicited oxidative stress (catalase, superoxide dismutase and glutathione-S-transferase activities) and heat shock responses. Thus, potentially unpinned on CO2-promoted protein removal and ionic equilibrium between hydrogen and reactive oxygen species, we found that co-occurring acidification decreased heavy metal accumulation and contributed to physiological homeostasis. Although this indicates that fish can be physiologically capable of withstanding future ocean conditions, additional experiments are needed to fully understand the biochemical repercussions of interactive stressors (additive, synergistic or antagonistic).
Collapse
Affiliation(s)
- Eduardo Sampaio
- MARE - Marine Environmental Sciences Centre & Laboratório Marítimo da Guia, Faculdade de Ciências, Universidade de Lisboa, Av. Nossa Senhora do Cabo 939, 2750-374 Cascais, Portugal.
| | - Ana R Lopes
- MARE - Marine Environmental Sciences Centre & Laboratório Marítimo da Guia, Faculdade de Ciências, Universidade de Lisboa, Av. Nossa Senhora do Cabo 939, 2750-374 Cascais, Portugal; UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829-516 Caparica, Portugal
| | - Sofia Francisco
- MARE - Marine Environmental Sciences Centre & Laboratório Marítimo da Guia, Faculdade de Ciências, Universidade de Lisboa, Av. Nossa Senhora do Cabo 939, 2750-374 Cascais, Portugal
| | - Jose R Paula
- MARE - Marine Environmental Sciences Centre & Laboratório Marítimo da Guia, Faculdade de Ciências, Universidade de Lisboa, Av. Nossa Senhora do Cabo 939, 2750-374 Cascais, Portugal
| | - Marta Pimentel
- MARE - Marine Environmental Sciences Centre & Laboratório Marítimo da Guia, Faculdade de Ciências, Universidade de Lisboa, Av. Nossa Senhora do Cabo 939, 2750-374 Cascais, Portugal
| | - Ana L Maulvault
- MARE - Marine Environmental Sciences Centre & Laboratório Marítimo da Guia, Faculdade de Ciências, Universidade de Lisboa, Av. Nossa Senhora do Cabo 939, 2750-374 Cascais, Portugal; Divisão de Aquacultura e Valorização (DivAV), Instituto Português do Mar e da Atmosfera (IPMA, I.P.), Av. Brasília, 1449-006 Lisboa, Portugal; Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), University of Porto, Rua das Bragas, 289, 4050-123 Porto, Portugal
| | - Tiago Repolho
- MARE - Marine Environmental Sciences Centre & Laboratório Marítimo da Guia, Faculdade de Ciências, Universidade de Lisboa, Av. Nossa Senhora do Cabo 939, 2750-374 Cascais, Portugal
| | - Tiago F Grilo
- MARE - Marine Environmental Sciences Centre & Laboratório Marítimo da Guia, Faculdade de Ciências, Universidade de Lisboa, Av. Nossa Senhora do Cabo 939, 2750-374 Cascais, Portugal
| | - Pedro Pousão-Ferreira
- Divisão de Aquacultura e Valorização (DivAV), Instituto Português do Mar e da Atmosfera (IPMA, I.P.), Av. Brasília, 1449-006 Lisboa, Portugal
| | - António Marques
- Divisão de Aquacultura e Valorização (DivAV), Instituto Português do Mar e da Atmosfera (IPMA, I.P.), Av. Brasília, 1449-006 Lisboa, Portugal; Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), University of Porto, Rua das Bragas, 289, 4050-123 Porto, Portugal
| | - Rui Rosa
- MARE - Marine Environmental Sciences Centre & Laboratório Marítimo da Guia, Faculdade de Ciências, Universidade de Lisboa, Av. Nossa Senhora do Cabo 939, 2750-374 Cascais, Portugal
| |
Collapse
|
7
|
Risher JF, Tucker P. Alkyl Mercury-Induced Toxicity: Multiple Mechanisms of Action. REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2017; 240:105-149. [PMID: 27161558 PMCID: PMC10508330 DOI: 10.1007/398_2016_1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
There are a number of mechanisms by which alkylmercury compounds cause toxic action in the body. Collectively, published studies reveal that there are some similarities between the mechanisms of the toxic action of the mono-alkyl mercury compounds methylmercury (MeHg) and ethylmercury (EtHg). This paper represents a summary of some of the studies regarding these mechanisms of action in order to facilitate the understanding of the many varied effects of alkylmercurials in the human body. The similarities in mechanisms of toxicity for MeHg and EtHg are presented and compared. The difference in manifested toxicity of MeHg and EtHg are likely the result of the differences in exposure, metabolism, and elimination from the body, rather than differences in mechanisms of action between the two.
Collapse
Affiliation(s)
- John F Risher
- Division of Toxicology and Human Health Sciences, Agency for Toxic Substances and Disease Registry, 1600 Clifton Road (MS F-58), Atlanta, GA, 30333, USA.
| | - Pamela Tucker
- Division of Toxicology and Human Health Sciences, Agency for Toxic Substances and Disease Registry, 1600 Clifton Road (MS F-58), Atlanta, GA, 30333, USA
| |
Collapse
|
8
|
Owoeye O, Arinola GO. A Vegetable, Launaea taraxacifolia, Mitigated Mercuric Chloride Alteration of the Microanatomy of Rat Brain. J Diet Suppl 2017; 14:613-625. [PMID: 28471730 DOI: 10.1080/19390211.2017.1288194] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Mercuric chloride is an environmental pollutant that affects the nervous systems of mammals. Oxidative damage is one of the mechanisms of its toxicity, and antioxidants should mitigate this effect. A vegetable with antioxidant activity is Launaea taraxacifolia, whose ethanolic extract (EELT) was investigated in this experiment to determine its effect against mercuric chloride (MC) intoxication in rat brain. Thirty male Wistar rats were randomly assigned into five groups (n = 6) as follows: control; propylene glycol; EELT (400 mg/kg bwt) for 19 days; MC (HgCl2) (4 mg/bwt) for 5 days from day 15 of the experiment; EELT+ MC, EELT (400 mg/kg bwt) for 14 days + MC (4 mg/bwt) for 5 days from day 15 of the experiment. All treatments were administered orally by gastric gavage. Behavioral tests were conducted on the 20th day, and rats were euthanized the same day. Blood and brain tissue were examined with regard to microanatomical parameters. Data were analyzed using analysis of variance with statistical significance set at p < .05. MC induced significant (19%) reduction of thrombocytes, which was ameliorated by 57% (p < .05) by pretreatment with EELT when compared with the MC group. Behavioral results showed that MC elicited significant reduction in transitions, rearings, forelimb grip strength, and latency of geotaxis. Histologically, MC induced alterations in the microanatomy of cerebral cortex, dentate gyrus, cornu ammonis 3, and cerebellum of rats. Treatment with EELT prior to MC administration significantly reduced the effect of MC on the hematological, behavioral, and ameliorated histological alterations of the brain. These findings may be attributed partially to the antioxidant property of EELT, which demonstrated protective effects against MC-induced behavioral parameters and alteration of microanatomy of rats' cerebral cortex, hippocampus, and cerebellum. In conclusion, EELT may be a valuable agent for further investigation in the prevention of acute neuropathy caused by inorganic mercury intoxication.
Collapse
Affiliation(s)
- Olatunde Owoeye
- a Department of Anatomy , College of Medicine, University of Ibadan , Ibadan , Nigeria
| | - Ganiyu O Arinola
- b Department of Chemical Pathology , College of Medicine, University of Ibadan , Ibadan , Nigeria
| |
Collapse
|
9
|
Hubbs-Tait L, Nation JR, Krebs NF, Bellinger DC. Neurotoxicants, Micronutrients, and Social Environments. Psychol Sci Public Interest 2016; 6:57-121. [DOI: 10.1111/j.1529-1006.2005.00024.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
SUMMARY—Systematic research evaluating the separate and interacting impacts of neurotoxicants, micronutrients, and social environments on children's cognition and behavior has only recently been initiated. Years of extensive human epidemiologic and animal experimental research document the deleterious impact of lead and other metals on the nervous system. However, discrepancies among human studies and between animal and human studies underscore the importance of variations in child nutrition as well as social and behavioral aspects of children's environments that mitigate or exacerbate the effects of neurotoxicants. In this monograph, we review existing research on the impact of neurotoxic metals, nutrients, and social environments and interactions across the three domains. We examine the literature on lead, mercury, manganese, and cadmium in terms of dispersal, epidemiology, experimental animal studies, effects of social environments, and effects of nutrition. Research documenting the negative impact of lead on cognition and behavior influenced reductions by the Center for Disease Control in child lead-screening guidelines from 30 micrograms per deciliter (μg/dL) in 1975 to 25 μg/dL in 1985 and to 10 μg/dL in 1991. A further reduction is currently being considered. Experimental animal research documents lead's alteration of glutamate-neurotransmitter (particularly N-methyl-D-aspartate) activity vital to learning and memory. In addition, lead induces changes in cholinergic and dopaminergic activity. Elevated lead concentrations in the blood are more common among children living in poverty and there is some evidence that socioeconomic status influences associations between lead and child outcomes. Micronutrients that influence the effects of lead include iron and zinc. Research documenting the negative impact of mercury on children (as well as adults) has resulted in a reference dose (RfD) of 0.1 microgram per kilogram of body weight per day (μg/kg/day). In animal studies, mercury interferes with glutamatergic, cholinergic, and dopaminergic activity. Although evidence for interactions of mercury with children's social contexts is minimal, researchers are examining interactions of mercury with several nutrients. Research on the effects of cadmium and manganese on child cognition and behavior is just beginning. Experimental animal research links cadmium to learning deficits, manganese to behaviors characteristic of Parkinson's disease, and both to altered dopaminergic functioning. We close our review with a discussion of policy implications, and we recommend interdisciplinary research that will enable us to bridge gaps within and across domains.
Collapse
Affiliation(s)
- Laura Hubbs-Tait
- Department of Human Development and Family Science, Oklahoma State University
| | | | - Nancy F. Krebs
- Department of Pediatrics, University of Colorado School of Medicine
| | - David C. Bellinger
- Department of Neurology, Harvard Medical School; Department of Environmental Health, Harvard School of Public Health; and Children's Hospital Boston
| |
Collapse
|
10
|
Krey A, Kwan M, Chan HM. In vivo and in vitro changes in neurochemical parameters related to mercury concentrations from specific brain regions of polar bears (Ursus maritimus). ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2014; 33:2463-2471. [PMID: 25264143 DOI: 10.1002/etc.2685] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 02/27/2014] [Accepted: 07/11/2014] [Indexed: 06/03/2023]
Abstract
Mercury (Hg) has been detected in polar bear brain tissue, but its biological effects are not well known. Relationships between Hg concentrations and neurochemical enzyme activities and receptor binding were assessed in the cerebellum, frontal lobes, and occipital lobes of 24 polar bears collected from Nunavik (Northern Quebec), Canada. The concentration-response relationship was further studied with in vitro experiments using pooled brain homogenate of 12 randomly chosen bears. In environmentally exposed brain samples, there was no correlative relationship between Hg concentration and cholinesterase (ChE) activity or muscarinic acetylcholine receptor (mAChR) binding in any of the 3 brain regions. Monoamine oxidase (MAO) activity in the occipital lobe showed a negative correlative relationship with total Hg concentration. In vitro experiments, however, demonstrated that Hg (mercuric chloride and methylmercury chloride) can inhibit ChE and MAO activities and muscarinic mAChR binding. These results show that Hg can alter neurobiochemical parameters but the current environmental Hg exposure level does have an effect on the neurochemistry of polar bears from northern Canada.
Collapse
Affiliation(s)
- Anke Krey
- Natural Resources and Environmental Studies, University of Northern British Columbia, Prince George, British Columbia, Canada
| | | | | |
Collapse
|
11
|
Ekinci M, Ceylan E, Keleş S, Cağatay HH, Apil A, Tanyıldız B, Uludag G. Toxic effects of chronic mercury exposure on the retinal nerve fiber layer and macular and choroidal thickness in industrial mercury battery workers. Med Sci Monit 2014; 20:1284-90. [PMID: 25056093 PMCID: PMC4136938 DOI: 10.12659/msm.890756] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Background The aim of this study was to evaluate the toxic effects of mercury on retinal nerve fiber layer thickness (RNFLT), macular thickness (MT), and choroidal thickness (CT) by using spectral-domain optical coherence tomography (SD-OCT) in battery industry workers who had been chronically exposed to mercury. Material/Methods Battery factory workers (n=31) and healthy non-factory employee controls (n=15) participated in the study. Participants were divided into 3 groups: Group 1 (n=15) was factory workers who had worked for more than 5 years in a mercury battery factory; Group 2 (n=16) was factory worker who had worked for less than 5 years in a mercury battery factory; and Group 3 (n=15) was healthy non-employees. Systemic symptoms were recorded. Ophthalmic examination included best-corrected visual acuity test, color vision test, full ophthalmologic examination, and SD-OCT of the RNLF, macula, and choroid. To determine mercury exposure, venous blood samples were collected and mercury levels were assessed. Results In our study group the most common systemic symptoms were insomnia (67.7%) and fatigue (67.7%). There were no significant differences between Group 1 and Group 2, but there were significant differences between Group 3 and both Group 1 and Group 2 in best-corrected visual acuity values (1=2<3), color vision scores, blood mercury levels, and duration (mean ±SD, range) of mercury exposure(1>2>3). OCT values of RNFLTs, MTs, and CTs of all 3 groups were statistically different from each another (1<2<3). Conclusions SD-OCT can be useful for evaluating the toxic effects of chronic exposure to mercury.
Collapse
Affiliation(s)
- Metin Ekinci
- Department of Ophthalmology, Kafkas University, Kars, Turkey
| | - Erdinç Ceylan
- Department of Ophthalmology, Erzurum Training and Research Hospital, Erzurum, Turkey
| | - Sadullah Keleş
- Department of Ophthalmology, Atatürk University, Erzurum, Turkey
| | | | - Aytekin Apil
- Department of Ophthalmology, Bakirkoy Training and Research Hospital, Istanbul, Turkey
| | - Burak Tanyıldız
- Department of Ophthalmology, Istanbul Faculty of Medicine, Istanbul, Turkey
| | - Gunay Uludag
- Department of Ophthalmology, Ağrı State Hospital, Ağrı, Turkey
| |
Collapse
|
12
|
Hajeb P, Sloth JJ, Shakibazadeh S, Mahyudin NA, Afsah-Hejri L. Toxic Elements in Food: Occurrence, Binding, and Reduction Approaches. Compr Rev Food Sci Food Saf 2014; 13:457-472. [DOI: 10.1111/1541-4337.12068] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 02/14/2014] [Indexed: 02/03/2023]
Affiliation(s)
- P. Hajeb
- Food Safety Research Centre (FOSREC); Faculty of Food Science and Technology; Universiti Putra Malaysia, 43400, UPM, Serdang; Selangor Malaysia
| | - J. J. Sloth
- National Food Inst; Technical Univ. of Denmark, Mørkhøj Bygade 19; DK-2860 Søborg Denmark
| | - Sh. Shakibazadeh
- Dept. of Aquaculture; Faculty of Agriculture; Universiti Putra Malaysia, 43400, UPM Serdang; Selangor Malaysia
| | - N. A. Mahyudin
- Food Safety Research Centre (FOSREC); Faculty of Food Science and Technology; Universiti Putra Malaysia, 43400, UPM, Serdang; Selangor Malaysia
| | - L. Afsah-Hejri
- Food Safety Research Centre (FOSREC); Faculty of Food Science and Technology; Universiti Putra Malaysia, 43400, UPM, Serdang; Selangor Malaysia
| |
Collapse
|
13
|
Mohamed Moosa Z, Daniels WMU, Mabandla MV. The effects of prenatal methylmercury exposure on trace element and antioxidant levels in rats following 6-hydroxydopamine-induced neuronal insult. Metab Brain Dis 2014; 29:459-69. [PMID: 24338101 DOI: 10.1007/s11011-013-9465-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 11/29/2013] [Indexed: 12/26/2022]
Abstract
Methylmercury (MeHg) is a metal toxin found commonly in the environment. Studies have shown severe neurotoxic effects of MeHg poisoning especially during pregnancy where it crosses the foetoplacental and the blood brain barrier of the foetus leading to neurodevelopmental deficits in the offspring. These deficits may predispose offspring to neurodegenerative diseases later in life. In this study we investigated the effects of prenatal methylmercury exposure (2.5 mg/L in drinking water from GND 1-GND 21) on the trace element status in the brain of adolescent offspring (PND 28). Total antioxidant capacity (TAC) was measured in their blood plasma. In a separate group of animals that was also exposed prenatally to MeHg, 6-hydroydopamine (6-OHDA) was administered at PND 60 as a model of neuronal insult. Trace element and TAC levels were compared before and after 6-OHDA exposure. Prenatal MeHg treatment alone resulted in significantly higher concentrations of zinc, copper, manganese and selenium in the brain of offspring at PND 28 (p < 0.05), when compared to controls. In contrast, brain iron levels in MeHg-exposed adolescent offspring were significantly lower than their controls (p < 0.05). Following 6-OHDA exposure, the levels of iron, zinc, copper and manganese were increased compared to sham-lesioned offspring (p < 0.05). Prenatal MeHg exposure further increased these trace element levels thereby promoting toxicity (p < 0.05). Total antioxidant capacity was not significantly different in MeHg and control groups prior to lesion. However, following 6-OHDA administration, MeHg-exposed animals had a significantly lower TAC than that of controls (p < 0.05). Brain TAC levels were higher in adult male rats than in female rats during adolescence however male rats that had been exposed to MeHg in utero failed to show this increase at PND 74. Prenatal MeHg exposure results in trace element dyshomeostasis in the brain of offspring and reduces total antioxidant capacity. This may reflect a mechanism by which methylmercury exerts its neurotoxicity and/or predispose offspring to further neurological insults during adulthood.
Collapse
Affiliation(s)
- Zulfiah Mohamed Moosa
- Discipline of Human Physiology, School of Laboratory Medicine and Medical Sciences, College of Health Sciences, University of KwaZulu-Natal, Westville Campus, Durban, 4000, South Africa,
| | | | | |
Collapse
|
14
|
Biomarkers of mercury exposure in the Amazon. BIOMED RESEARCH INTERNATIONAL 2014; 2014:867069. [PMID: 24895619 PMCID: PMC4020561 DOI: 10.1155/2014/867069] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2013] [Accepted: 04/08/2014] [Indexed: 11/22/2022]
Abstract
Mercury exposure in the Amazon has been studied since the 1980s decade and the assessment of human mercury exposure in the Amazon is difficult given that the natural occurrence of this metal is high and the concentration of mercury in biological samples of this population exceeds the standardized value of normality established by WHO. Few studies have focused on the discovery of mercury biomarkers in the region's population. In this way, some studies have used genetics as well as immunological and cytogenetic tools in order to find a molecular biomarker for assessing the toxicological effect of mercury in the Amazonian population. Most of those studies focused attention on the relation between mercury exposure and autoimmunity and, because of that, they will be discussed in more detail. Here we introduce the general aspects involved with each biomarker that was studied in the region in order to contextualize the reader and add information about the Amazonian life style and health that may be considered for future studies. We hope that, in the future, the toxicological studies in this field use high technological tools, such as the next generation sequencing and proteomics skills, in order to comprehend basic questions regarding the metabolic route of mercury in populations that are under constant exposure, such as in the Amazon.
Collapse
|
15
|
Zhang H, Feng X, Chan HM, Larssen T. New insights into traditional health risk assessments of mercury exposure: implications of selenium. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:1206-1212. [PMID: 24377354 DOI: 10.1021/es4051082] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
There is increasing evidence that selenium (Se) has a significant effect on mercury (Hg) toxicology; however, Hg exposure risk assessments usually consider only the amount of Hg present in the environment or in food. On the basis of the present understanding of mechanisms of interaction between Se and Hg, the physiology/toxicology of Se, and the toxicology of Hg, we propose a new criterion for Se/Hg exposure assessment. This criterion, which is based on Se-Hg interactions, considers not only the toxicological consequences of Hg exposure but also the benefits and/or adverse effects of Se intake, especially the adverse effects related to a Se deficiency/excess. According to an illustrative assessment based on the new criterion and nine existing criteria, large knowledge gaps in the traditional assessments of exposure to Hg and/or Se were found, including those that assessed the interactions between Hg and Se. These results suggest that future assessments of Hg exposure (or Se intake) should include both Se and Hg.
Collapse
Affiliation(s)
- Hua Zhang
- Norwegian Institute for Water Research (NIVA) , Gaustadalléen 21, 0349 Oslo, Norway
| | | | | | | |
Collapse
|
16
|
Kanda H, Shinkai Y, Kumagai Y. S-Mercuration of cellular proteins by methylmercury and its toxicological implications. J Toxicol Sci 2014; 39:687-700. [DOI: 10.2131/jts.39.687] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Hironori Kanda
- Doctoral Program in Biomedical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba
| | - Yasuhiro Shinkai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba
| | - Yoshito Kumagai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba
| |
Collapse
|
17
|
Metal Species in Biology: Bottom-Up and Top-Down LC Approaches in Applied Toxicological Research. ACTA ACUST UNITED AC 2013. [DOI: 10.1155/2013/801840] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Since the inception of liquid chromatography (LC) more than 100 years ago this separation technique has been developed into a powerful analytical tool that is frequently applied in life science research. To this end, unique insights into the interaction of metal species (throughout this manuscript “metal species” refers to “toxic metals, metalloid compounds, and metal-based drugs” and “toxic metals” to “toxic metals and metalloid compounds”) with endogenous ligands can be obtained by using LC approaches that involve their hyphenation with inductively coupled plasma-based element specific detectors. This review aims to provide a synopsis of the different LC approaches which may be employed to advance our understanding of these interactions either in a “bottom-up” or a “top-down” manner. In the “bottom-up” LC-configuration, endogenous ligands are introduced into a physiologically relevant mobile phase buffer, and the metal species of interest is injected. Subsequent “interrogation” of the on-column formed complex(es) by employing a suitable separation mechanism (e.g., size exclusion chromatography or reversed-phase LC) while changing the ligand concentration(s), the column temperature or the pH can provide valuable insight into the formation of complexes under near physiological conditions. This approach allows to establish the relative stability and hydrophobicity of metal-ligand complexes as well as the dynamic coordination of a metal species (injected) to two ligands (dissolved in the mobile phase). Conversely, the “top-down” analysis of a biological fluid (e.g., blood plasma) by LC (e.g., using size exclusion chromatography) can be used to determine the size distribution of endogenous metalloproteins which are collectively referred to as the “metalloproteome”. This approach can provide unique insight into the metabolism and the plasma protein binding of metal species, and can simultaneously visualize the dose-dependent perturbation of the metalloproteome by a particular metal species. The concerted application of these LC approaches is destined to provide new insight into biochemical processes which represent an important starting point to advance human health in the 21st century.
Collapse
|
18
|
Radonjic M, Cappaert NLM, de Vries EFJ, de Esch CEF, Kuper FC, van Waarde A, Dierckx RAJO, Wadman WJ, Wolterbeek APM, Stierum RH, de Groot DMG. Delay and Impairment in Brain Development and Function in Rat Offspring After Maternal Exposure to Methylmercury. Toxicol Sci 2013; 133:112-24. [DOI: 10.1093/toxsci/kft024] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
|
19
|
Hajeb P, Jinap S. Reduction of mercury from mackerel fillet using combined solution of cysteine, EDTA, and sodium chloride. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2012; 60:6069-6076. [PMID: 22515475 DOI: 10.1021/jf300582j] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
An acidic solution containing mercury chelating agents to eliminate mercury in raw fish (mackerel) fillet was developed. The solution contained hydrochloric acid, sodium hydroxide, cysteine, EDTA, and NaCl. The optimum conditions for mercury reduction were achieved using response surface methodology (RSM) at cysteine concentration of 1.25%, EDTA of 275 mg/L, NaCl of 0.5%, pH of 3.75, and exposure time of 18 min. The optimized conditions produced a solution which can remove up to 91% mercury from raw fish fillet. Cysteine and EDTA were identified as potential chelating agents with the greatest potential for use. The solution can be employed in fish industries to reduce mercury in highly contaminated fish.
Collapse
Affiliation(s)
- P Hajeb
- Centre of Excellence for Food Safety Research (CEFSR), Faculty of Food Science and Technology, and ‡Institute of Tropical Agriculture, Universiti Putra Malaysia , 43400 UPM, Serdang, Selangor, Malaysia
| | | |
Collapse
|
20
|
Application of Neurochemical Markers for Assessing Health Effects after Developmental Methylmercury and PCB Coexposure. J Toxicol 2012; 2012:216032. [PMID: 22505887 PMCID: PMC3306999 DOI: 10.1155/2012/216032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 10/21/2011] [Indexed: 11/17/2022] Open
Abstract
Cholinergic muscarinic receptors (MRs) and monoamine oxidase activity (MAO-B), expressed both in brain and blood cells, were investigated in animals and exposed subjects to assess (i) MeHg (0.5–1 mg/kg/day GD7-PD7) and/or PCB153 (20 mg/kg/day GD10–GD16) effects on cerebellar MAO-B and MRs, and lymphocyte MRs, in dams and offspring 21 days postpartum; (ii) MAO-B in platelets and MRs in lymphocytes of a Faroese 7-year-old children cohort, prenatally exposed to MeHg/PCBs. Animal Data. MAO-B was altered in male cerebellum by MeHg, PCB153, and their combination (35%, 45%, and 25% decrease, resp.). Cerebellar MRs were enhanced by MeHg alone in dams (87%) and male pups (27%). PCB153 alone and in mixture did not modify cerebellar MRs. Similarly to brain, lymphocyte MRs were enhanced in both dams and offspring by MeHg alone. All changes were caused by 1 MeHg mg/kg/day, the lower dose was ineffective. Human Data. Both biomarkers showed homogeneous distributions within the cohort (MRs, range 0.1–36.78 fmol/million cells; MAO-B, 0.95–14.95 nmol/mg protein/h). No correlation was found between the two biomarkers and neurotoxicant concentrations in blood (pre- and postnatally).
Collapse
|
21
|
Yuan Y. Methylmercury: a potential environmental risk factor contributing to epileptogenesis. Neurotoxicology 2012; 33:119-26. [PMID: 22206970 PMCID: PMC3285480 DOI: 10.1016/j.neuro.2011.12.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 12/12/2011] [Accepted: 12/14/2011] [Indexed: 12/29/2022]
Abstract
Epilepsy or seizure disorder is one of the most common neurological diseases in humans. Although genetic mutations in ion channels and receptors and some other risk factors such as brain injury are linked to epileptogenesis, the underlying cause for the majority of epilepsy cases remains unknown. Gene-environment interactions are thought to play a critical role in the etiology of epilepsy. Exposure to environmental chemicals is an important risk factor. Methylmercury (MeHg) is a prominent environmental neurotoxicant, which targets primarily the central nervous system (CNS). Patients or animals with acute or chronic MeHg poisoning often display epileptic seizures or show increased susceptibility to seizures, suggesting that MeHg exposure may be associated with epileptogenesis. This mini-review highlights the effects of MeHg exposure, especially developmental exposure, on the susceptibility of humans and animals to seizures, and discusses the potential role of low level MeHg exposure in epileptogenesis. This review also proposes that a preferential effect of MeHg on the inhibitory GABAergic system, leading to disinhibition of excitatory glutamatergic function, may be one of the potential mechanisms underlying MeHg-induced changes in seizure susceptibility.
Collapse
Affiliation(s)
- Yukun Yuan
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, USA.
| |
Collapse
|
22
|
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
|
23
|
Pal PB, Pal S, Das J, Sil PC. Modulation of mercury-induced mitochondria-dependent apoptosis by glycine in hepatocytes. Amino Acids 2011; 42:1669-83. [PMID: 21373768 DOI: 10.1007/s00726-011-0869-3] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Accepted: 02/18/2011] [Indexed: 12/16/2022]
Abstract
Mercury (Hg) is one of the universal environmental pollutants and is responsible for various organ pathophysiology including oxidative stress-induced hepatic disorders. In the present study, we aimed to explore the protective role of glycine in Hg-induced cytotoxicity and cell death in murine hepatocytes. Exposure of mercury (20 μM), in the form HgCl2 for 1 h, significantly enhanced the ALT and ALP leakage, increased reactive oxygen species production, reduced cell viability and distorted the antioxidant status of hepatocytes. Flow cytometric analyses shows that Hg-induced apoptotic death in hepatocytes. Mechanism of this pathophysiology involves reduced mitochondrial membrane potential, variations in Bcl-2/Bad proteins, activation of caspases and cleavage of PARP protein. In addition, Hg distinctly increased NF-κB phosphorylation in association with IKKα phosphorylation and IκBα degradation. Concurrent treatment with glycine (45 mM), however, reduced Hg-induced oxidative stress, attenuated the changes in NF-κB phosphorylation and protects hepatocytes from Hg-induced apoptotic death. Hg also distinctly increased the phosphorylation of p38, JNK and ERK mitogen-activated protein kinase (MAPKs). Glycine treatment suppressed these apoptotic events, signifying its protective role in Hg-induced hepatocyte apoptosis as referred by reduction of p38, JNK and ERK MAPK signaling pathways. Results suggest that glycine can modulate Hg-induced oxidative stress and apoptosis in hepatocytes probably because of its antioxidant activity and functioning via mitochondria-dependent pathways and could be a beneficial agent in oxidative stress-mediated liver diseases.
Collapse
Affiliation(s)
- Pabitra Bikash Pal
- Division of Molecular Medicine, Bose Institute, P-1/12, CIT Scheme VII M, Kolkata, 700054, West Bengal, India
| | | | | | | |
Collapse
|
24
|
Developmental exposure to methylmercury and 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB153) affects cerebral dopamine D1-like and D2-like receptors of weanling and pubertal rats. Arch Toxicol 2011; 85:1281-94. [DOI: 10.1007/s00204-011-0660-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Accepted: 01/25/2011] [Indexed: 11/25/2022]
|
25
|
Abstract
Acute or chronic mercury exposure can cause adverse effects during any period of development. Mercury is a highly toxic element; there is no known safe level of exposure. Ideally, neither children nor adults should have any mercury in their bodies because it provides no physiological benefit. Prenatal and postnatal mercury exposures occur frequently in many different ways. Pediatricians, nurses, and other health care providers should understand the scope of mercury exposures and health problems among children and be prepared to handle mercury exposures in medical practice. Prevention is the key to reducing mercury poisoning. Mercury exists in different chemical forms: elemental (or metallic), inorganic, and organic (methylmercury and ethyl mercury). Mercury exposure can cause acute and chronic intoxication at low levels of exposure. Mercury is neuro-, nephro-, and immunotoxic. The development of the child in utero and early in life is at particular risk. Mercury is ubiquitous and persistent. Mercury is a global pollutant, bio-accumulating, mainly through the aquatic food chain, resulting in a serious health hazard for children. This article provides an extensive review of mercury exposure and children's health.
Collapse
Affiliation(s)
- Stephan Bose-O'Reilly
- Institute of Public Health, Medical Decision Making and Health Technology Assessment, Department of Public Health, Information Systems and Health Technology Assessment, UMIT-University for Health Sciences, Medical Informatics and Technology, Hall i.T, Austria
| | | | | | | |
Collapse
|
26
|
Bose-O'Reilly S, McCarty KM, Steckling N, Lettmeier B. Mercury exposure and children's health. Curr Probl Pediatr Adolesc Health Care 2010; 40:186-215. [PMID: 20816346 DOI: 10.1016/j.cppeds.2010.07.002.mercury] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Acute or chronic mercury exposure can cause adverse effects during any period of development. Mercury is a highly toxic element; there is no known safe level of exposure. Ideally, neither children nor adults should have any mercury in their bodies because it provides no physiological benefit. Prenatal and postnatal mercury exposures occur frequently in many different ways. Pediatricians, nurses, and other health care providers should understand the scope of mercury exposures and health problems among children and be prepared to handle mercury exposures in medical practice. Prevention is the key to reducing mercury poisoning. Mercury exists in different chemical forms: elemental (or metallic), inorganic, and organic (methylmercury and ethyl mercury). Mercury exposure can cause acute and chronic intoxication at low levels of exposure. Mercury is neuro-, nephro-, and immunotoxic. The development of the child in utero and early in life is at particular risk. Mercury is ubiquitous and persistent. Mercury is a global pollutant, bio-accumulating, mainly through the aquatic food chain, resulting in a serious health hazard for children. This article provides an extensive review of mercury exposure and children's health.
Collapse
Affiliation(s)
- Stephan Bose-O'Reilly
- Institute of Public Health, Medical Decision Making and Health Technology Assessment, Department of Public Health, Information Systems and Health Technology Assessment, UMIT-University for Health Sciences, Medical Informatics and Technology, Hall i.T, Austria
| | | | | | | |
Collapse
|
27
|
Basu N, Scheuhammer A, Rouvinen-Watt K, Grochowina N, Evans D, Chan HM. Variation of cholinergic biomarkers in brain regions and blood components of captive mink. ENVIRONMENTAL MONITORING AND ASSESSMENT 2010; 162:377-386. [PMID: 19267210 DOI: 10.1007/s10661-009-0803-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Accepted: 01/27/2009] [Indexed: 05/27/2023]
Abstract
Studies are increasingly using cholinergic parameters as biomarkers of early neurotoxicity, but few have characterized this system in ecologically relevant model organisms. In the present study, key neurochemicals in the cholinergic pathway were measured and analyzed from discrete parts of brain and blood from captive mink (Mustela vison). Similar to other mammals, the regional distribution of cholinergic parameters in the brain could be ranked from highest to lowest as: basal ganglia > occipital cortex > brain stem > cerebellum (F (3,192) = 172.1, p < 0.001). Higher variation in cholinergic parameters was found in the cerebellum (coefficient of variation = 34.9%), and the least variation was measured in the brain stem (19.7%). Variation was also assessed by calculating the difference between the lowest and highest measures among individual animals: choline acetyltransferase (1.6x fold difference), cholinesterase (2.0x), muscarinic receptor levels (2.4x), acetylcholine (3.7x), nicotinic receptor levels (3.9x), and choline transporter (5.0x). In blood samples, activity and inter-individual variation of cholinesterase was highest in whole blood and lowest in plasma and serum. By using captive mink of a common genetic source, age, gender, and rearing conditions, these data help establish normal levels, ranges, and variations of cholinergic biomarkers among brain regions, blood components, and individual animals. Such information may better enable the utility of cholinergic biomarkers in environmental assessments.
Collapse
Affiliation(s)
- Niladri Basu
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI 48109, USA.
| | | | | | | | | | | |
Collapse
|
28
|
Aschner* M, Onishchenko N, Ceccatelli S. Toxicology of Alkylmercury Compounds. ORGANOMETALLICS IN ENVIRONMENT AND TOXICOLOGY 2010. [DOI: 10.1039/9781849730822-00403] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Methylmercury is a global pollutant and potent neurotoxin whose abundance in the food chain mandates additional studies on the consequences and mechanisms of its toxicity to the central nervous system. Formulation of our new hypotheses was predicated on our appreciation for (a) the remarkable affinity of mercurials for the anionic form of sulfhydryl (-SH) groups, and (b) the essential role of thiols in protein biochemistry. The present chapter addresses pathways to human exposure of various mercury compounds, highlighting their neurotoxicity and potential involvement in neurotoxic injury and neurodegenerative changes, both in the developing and senescent brain. Mechanisms that trigger these effects are discussed in detail.
Collapse
Affiliation(s)
- Michael Aschner*
- Vanderbilt University School of Medicine, Department of Pediatrics Pharmacology, and the Kennedy Center for Research on Human Development Nashville TN 37232 USA
| | | | - Sandra Ceccatelli
- Karolinska Institute, Department of Neuroscience SE-17177 Stockholm Sweden
| |
Collapse
|
29
|
Mammalian wildlife as complementary models in environmental neurotoxicology. Neurotoxicol Teratol 2010; 32:114-9. [DOI: 10.1016/j.ntt.2008.12.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2008] [Revised: 12/12/2008] [Accepted: 12/16/2008] [Indexed: 11/23/2022]
|
30
|
Valentini J, Vicentini J, Grotto D, Tonello R, Garcia SC, Barbosa F. Sub-chronic exposure to methylmercury at low levels decreases butyrylcholinesterase activity in rats. Basic Clin Pharmacol Toxicol 2009; 106:95-9. [PMID: 19874286 DOI: 10.1111/j.1742-7843.2009.00475.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this study, we examined the effects of low levels and sub-chronic exposure to methylmercury (MeHg) on butyrylcholinesterase (BuChE) activity in rats. Moreover, we examined the relationship between BuChE activity and oxidative stress biomarkers [delta-aminolevulinic acid dehydratase (delta-ALA-D) and malondialdehyde levels (MDA)] in the same animals. Rats were separated into three groups (eight animals per group): (Group I) received water by gavage; (Group II) received MeHg (30 microg/kg/day) by gavage; (Group III) received MeHg (100 microg/kg/day). The time of exposure was 90 days. BuChE and ALA-D activities were measured in serum and blood, respectively; whereas MDA levels were measured in plasma. We found BuChE and ALA-D activities decreased in groups II and III compared to the control group. Moreover, we found an interesting negative correlation between plasmatic BuChE activity and MDA (r = -0.85; p < 0.01) and a positive correlation between plasmatic BuChE activity and ALA-D activities (r = 0.78; p < 0.01), thus suggesting a possible relationship between oxidative damage promoted by MeHg exposure and the decrease of BuChE activity. In conclusion, long-term exposure to low doses of MeHg decreases plasmatic BuChE activity. Moreover, the decrease in the enzyme is strongly correlated with the oxidative stress promoted by the metal exposure. This preliminary finding highlights a possible mechanism for MeHg to reduce BuChE activity in plasma. Additionally, this enzyme could be an auxiliary biomarker on the evaluation of MeHg exposure.
Collapse
Affiliation(s)
- Juliana Valentini
- Department of Clinical, Toxicological and Bromatological Analysis, Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, São Paulo, Brazil
| | | | | | | | | | | |
Collapse
|
31
|
Coccini T, Manzo L, Debes F, Steuerwald U, Weihe P, Grandjean P. No changes in lymphocyte muscarinic receptors and platelet monoamine oxidase-B examined as surrogate central nervous system biomarkers in a Faroese children cohort prenatally exposed to methylmercury and polychlorinated biphenyls. Biomarkers 2009; 14:67-76. [PMID: 19330584 DOI: 10.1080/13547500902783739] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Experimental evidence suggests that monoamine oxidase B (MAO-B) and muscarinic cholinergic receptors (mAChRs) are involved in the pathogenesis of neurotoxicity caused by methylmercury and polychlorinated biphenyls (PCBs). Blood samples from 7-year-old exposed children were analyzed for platelet MAO-B and lymphocyte mAChRs as potential markers of exposure to these neurotoxicants. The blood neurotoxicity biomarkers were compared with prenatal and current exposures and with neuropsychological test results. Both biomarkers showed homogeneous distributions within this cohort (mAChR, range 0.04-36.78 fmol/million cells; MAO-B, 0.95-14.95 nmol mg(-1) protein h(-1)). No correlation was found between the two biomarkers and either blood neurotoxicant concentrations or clinical findings. MAO-B and mAChR sensitivity may not be sufficiently high to assess early, subclinical responses to low/moderate methylmercury and/or PCB exposure, whereas these markers are significantly altered in sustained exposure scenarios, as shown by clinical studies in drug addicts or patients treated with psychopharmacological agents.
Collapse
Affiliation(s)
- Teresa Coccini
- IRCCS Salvatore Maugeri Foundation, Toxicology Division, Institute of Pavia, Italy.
| | | | | | | | | | | |
Collapse
|
32
|
Bensoussan H, Grancolas L, Dhieux-Lestaevel B, Delissen O, Vacher CM, Dublineau I, Voisin P, Gourmelon P, Taouis M, Lestaevel P. Heavy metal uranium affects the brain cholinergic system in rat following sub-chronic and chronic exposure. Toxicology 2009; 261:59-67. [PMID: 19409444 DOI: 10.1016/j.tox.2009.04.054] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Revised: 04/20/2009] [Accepted: 04/21/2009] [Indexed: 12/01/2022]
Abstract
Uranium is a heavy metal naturally present in the environment that may be chronically ingested by the population. Previous studies have shown that uranium is present in the brain and alters behaviour, notably locomotor activity, sensorimotor ability, sleep/wake cycle and the memory process, but also metabolism of neurotransmitters. The cholinergic system mediates many cognitive systems, including those disturbed after chronic exposure to uranium i.e., spatial memory, sleep/wake cycle and locomotor activity. The objective of this study was to assess whether these disorders follow uranium-induced alteration of the cholinergic system. In comparison with 40 control rats, 40 rats drank 40 mg/L uranyl nitrate for 1.5 or 9 months. Cortex and hippocampus were removed and gene expression and protein level were analysed to determine potential changes in cholinergic receptors and acetylcholine levels. The expression of genes showed various alterations in the two brain areas after short- and long-term exposure. Nevertheless, protein levels of the choline acetyltransferase enzyme (ChAT), the vesicular transporter of acetylcholine (VAChT) and the nicotinic receptor beta2 sub-unit (nAChRbeta2) were unmodified in all cases of the experiment and muscarinic receptor type 1 (m1AChR) protein level was disturbed only after 9 months of exposure in the cortex (-30%). Acetylcholine levels were unchanged in the hippocampus after 1.5 and 9 months, but were decreased in the cortex after 1.5 months only (-22%). Acetylcholinesterase (AChE) activity was also unchanged in the hippocampus but decreased in the cortex after 1.5 and 9 months (-16% and -18%, respectively). Taken together, these data indicate that the cholinergic system is a target of uranium exposure in a structure-dependent and time-dependent manner. These cholinergic alterations could participate in behavioural impairments.
Collapse
Affiliation(s)
- Helene Bensoussan
- Institut de RadioProtection et de Sûreté Nucléaire, Département de la Radioprotection de l'Homme, Service de Radiobiologie et d'Epidémiologie, Laboratoire de Radiotoxicologie Expérimentale, BP 17, F-92262 Fontenay-aux-Roses Cedex, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Helmcke KJ, Syversen T, Miller DM, Aschner M. Characterization of the effects of methylmercury on Caenorhabditis elegans. Toxicol Appl Pharmacol 2009; 240:265-72. [PMID: 19341752 DOI: 10.1016/j.taap.2009.03.013] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 03/11/2009] [Accepted: 03/23/2009] [Indexed: 11/19/2022]
Abstract
The rising prevalence of methylmercury (MeHg) in seafood and in the global environment provides an impetus for delineating the mechanism of the toxicity of MeHg. Deleterious effects of MeHg have been widely observed in humans and in other mammals, the most striking of which occur in the nervous system. Here we test the model organism, Caenorhabditis elegans (C. elegans), for MeHg toxicity. The simple, well-defined anatomy of the C. elegans nervous system and its ready visualization with green fluorescent protein (GFP) markers facilitated our study of the effects of methylmercuric chloride (MeHgCl) on neural development. Although MeHgCl was lethal to C. elegans, induced a developmental delay, and decreased pharyngeal pumping, other traits including lifespan, brood size, swimming rate, and nervous system morphology were not obviously perturbed in animals that survived MeHgCl exposure. Despite the limited effects of MeHgCl on C. elegans development and behavior, intracellular mercury (Hg) concentrations (<or=3 ng Hg/mg protein) in MeHgCl-treated nematodes approached levels that are highly toxic to mammals. If MeHgCl reaches these concentrations throughout the animal, this finding indicates that C. elegans cells, particularly neurons, may be less sensitive to MeHgCl toxicity than mammalian cells. We propose, therefore, that C. elegans should be a useful model for discovering intrinsic mechanisms that confer resistance to MeHgCl exposure.
Collapse
Affiliation(s)
- Kirsten J Helmcke
- Pharmacology Department, Vanderbilt University Medical Center, Nashville, TN 37232-0414, USA
| | | | | | | |
Collapse
|
34
|
Castoldi AF, Onishchenko N, Johansson C, Coccini T, Roda E, Vahter M, Ceccatelli S, Manzo L. Neurodevelopmental toxicity of methylmercury: Laboratory animal data and their contribution to human risk assessment. Regul Toxicol Pharmacol 2008; 51:215-29. [PMID: 18482784 DOI: 10.1016/j.yrtph.2008.03.005] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2007] [Revised: 01/28/2008] [Accepted: 03/18/2008] [Indexed: 11/28/2022]
Abstract
Methylmercury (MeHg) is one of the most significant public health hazards. The clinical findings in the victims of the Japanese and Iraqi outbreaks have disclosed the pronounced susceptibility of the developing brain to MeHg poisoning. This notion has triggered worldwide scientific attention toward the long-term consequences of prenatal exposure on child development in communities with chronic low level dietary exposure. MeHg neurodevelopmental effects have been extensively investigated in laboratory animals under well-controlled exposure conditions. This article provides an updated overview of the main neuromorphological and neurobehavioral changes reported in non-human primates and rodents following developmental exposure to MeHg. Different aspects of MeHg's effects on the immature organism are reported, with particular reference to the delayed onset of symptoms and the persistency of central nervous system (CNS) injury/dysfunction. Particular attention is paid to the comparative toxicity assessment across species, and to the degree of concordance/discordance between human and animal data. The contribution of animal studies to define the role of potential effect modifiers and variables on MeHg dose-response relationships is also addressed. The ultimate goal is to discuss the relevance of laboratory animal results, as a complementary tool to human data, with regard to the human risk assessment process.
Collapse
Affiliation(s)
- Anna F Castoldi
- Toxicology Division, University of Pavia, Via Palestro 26, 27100 Pavia, Italy.
| | | | | | | | | | | | | | | |
Collapse
|
35
|
Roda E, Coccini T, Acerbi D, Castoldi A, Bernocchi G, Manzo L. Cerebellum cholinergic muscarinic receptor (subtype-2 and -3) and cytoarchitecture after developmental exposure to methylmercury: an immunohistochemical study in rat. J Chem Neuroanat 2008; 35:285-94. [PMID: 18358697 DOI: 10.1016/j.jchemneu.2008.01.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2007] [Revised: 01/22/2008] [Accepted: 01/22/2008] [Indexed: 11/27/2022]
Abstract
The developing central nervous system (CNS) is a target of the environmental toxicant methylmercury (MeHg), and the cerebellum seems the most susceptible tissue in response to this neurotoxicant. The cholinergic system is essential for brain development, acting as a modulator of neuronal proliferation, migration and differentiation processes; its muscarinic receptors (MRs) play pivotal roles in regulating important basic physiologic functions. By immunohistochemistry, we investigated the effects of perinatal (GD7-PD21) MeHg (0.5 mg/kg bw/day in drinking water) administration on cerebellum of mature (PD36) and immature (PD21) rats, evaluating the: (i) M2- and M3-MR expression; (ii) presence of gliosis; (iii) cytoarchitecture alterations. Regarding to M2-MRs, we showed that: at PD21, MeHg-treated animals did not display any differences compared to controls, while, at PD36 there was a significant increase of M2-immunopositive Bergmann cells in the molecular layer (ML), suggesting a MeHg-related cytotoxic effect. Similarly to M2-MRs, at PD21 the M3-MRs were not affected by MeHg, while, at PD36 a lacking immunoreactivity of the granular layer (IGL) was observed after MeHg treatment. In MeHg-treated rats, at both developmental points, we showed reactive gliosis, e.g. a significant increase in Bergmann glia of the ML and astrocytes of the IGL, identified by their expression of glial fibrillar acidic protein. No MeHg-related effects on Purkinje cells were detected neither at weaning nor at puberty. These findings suggest: (i) a delayed MeHg exposure-related effect on M2- and M3-MRs, (ii) an overt MeHg-related cytotoxic effect on cerebellar oligodendroglia, e.g. reactive gliosis, (iii) a selective vulnerability of granule cells and Purkinje neurons to MeHg, with the latter that remain unharmed.
Collapse
Affiliation(s)
- Elisa Roda
- University of Pavia, Department of Internal Medicine and Therapeutics, Toxicology Division, Pavia, Italy.
| | | | | | | | | | | |
Collapse
|
36
|
Castoldi AF, Johansson C, Onishchenko N, Coccini T, Roda E, Vahter M, Ceccatelli S, Manzo L. Human developmental neurotoxicity of methylmercury: impact of variables and risk modifiers. Regul Toxicol Pharmacol 2008; 51:201-14. [PMID: 18367301 DOI: 10.1016/j.yrtph.2008.01.016] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2007] [Revised: 01/28/2008] [Accepted: 01/30/2008] [Indexed: 11/26/2022]
Abstract
Methylmercury (MeHg) is a widespread environmental and food toxicant which has long been known to affect neurodevelopment in both humans and experimental animals. Risk assessment for MeHg is mainly based on human data coming from the massive episodes of poisoning in Japan and Iraq, as well as from large scale epidemiological studies concerning childhood development and neurotoxicity in relation to in utero exposure in various fish eating communities around the world. Despite the extensive literature and research, the threshold dose for MeHg neurotoxic effects is still unclear, in particular when it comes to subtle effects on neurobehaviour. In this article clinical and epidemiological findings concerning the neurodevelopmental toxicity of MeHg are reviewed. Much attention is focussed on the potential impact of factors, such as diet and nutrition, gender, pattern of exposure and co-exposure to other neurotoxic pollutants, which may modulate MeHg toxic effects. These factors, together with the notion that some symptoms may ensue or exacerbate with aging, contribute to the difficulties in the definition of safe levels for developmental exposure.
Collapse
Affiliation(s)
- Anna F Castoldi
- Toxicology Division, University of Pavia, Via Palestro 26, 27100 Pavia, Italy.
| | | | | | | | | | | | | | | |
Collapse
|
37
|
Vitalone A, Catalani A, Chiodi V, Cinque C, Fattori V, Goldoni M, Matteucci P, Poli D, Zuena AR, Costa LG. Neurobehavioral assessment of rats exposed to low doses of PCB126 and methyl mercury during development. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2008; 25:103-113. [PMID: 21783843 DOI: 10.1016/j.etap.2007.09.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Revised: 09/14/2007] [Accepted: 09/19/2007] [Indexed: 05/31/2023]
Abstract
Epidemiological and laboratory studies have suggested that polychlorinated biphenyls (PCBs) and methyl mercury (MeHg) may have additive or synergistic effects on CNS function. Aim of this study was to characterize the effects of exposure to low levels of MeHg (0.5mg/kgday in drinking water) and PCB126 (100ng/kgday in food), alone and in combination, on neurobehavioral development in Wistar rats. Dams were treated from gestational day 7 to post-natal day (PND) 21. Animals were tested for developmental landmarks and reflexes (PND1-21), attention deficits (PND40), locomotor activity (PND30, 110), spatial learning (PND75), coordination and balance (PND90), object discrimination (PND80), anxiety (PND100), and conditioned learning (PND110). Parameters related to pregnancy, sex ratio at birth, and physical development (at weaning) did not differ among groups, though PCB126 decreased number of pups at birth. A slight delay in negative geotaxis was found in female rats in all treatment groups. No significant effects were seen in attention, coordination and balance, object discrimination, and spatial and conditioned learning. Increased motor activity was present in PCB126-treated male and in MeHg+PCB-treated female rats in the elevated plus maze test, and in PCB126-treated male rats in the open field test (PND110). The results do not support the hypothesis that co-exposure to MeHg and PCB126 results in additive or synergistic effects. This finding is in agreement with more recent in vitro and in vivo studies.
Collapse
Affiliation(s)
- Annabella Vitalone
- Department of Human Anatomy, Pharmacology and Forensic Sciences, University of Parma Medical School, Parma, Via Volturno 39, 43100 Parma, Italy
| | | | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Johansson C, Castoldi AF, Onishchenko N, Manzo L, Vahter M, Ceccatelli S. Neurobehavioural and molecular changes induced by methylmercury exposure during development. Neurotox Res 2007; 11:241-60. [PMID: 17449462 DOI: 10.1007/bf03033570] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
There is an increasing body of evidence on the possible environmental influence on neurodevelopmental and neurodegenerative disorders. Both experimental and epidemiological studies have demonstrated the distinctive susceptibility of the developing brain to environmental factors such as lead, mercury and polychlorinated biphenyls at levels of exposure that have no detectable effects in adults. Methylmercury (MeHg) has long been known to affect neurodevelopment in both humans and experimental animals. Neurobehavioural effects reported include altered motoric function and memory and learning disabilities. In addition, there is evidence from recent experimental neurodevelopmental studies that MeHg can induce depression-like behaviour. Several mechanisms have been suggested from in vivo- and in vitro-studies, such as effects on neurotransmitter systems, induction of oxidative stress and disruption of microtubules and intracellular calcium homeostasis. Recent in vitro data show that very low levels of MeHg can inhibit neuronal differentiation of neural stem cells. This review summarises what is currently known about the neurodevelopmental effects of MeHg and consider the strength of different experimental approaches to study the effects of environmentally relevant exposure in vivo and in vitro.
Collapse
Affiliation(s)
- Carolina Johansson
- Division of Toxicology and Neurotoxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
| | | | | | | | | | | |
Collapse
|
39
|
Coccini T, Roda E, Castoldi AF, Goldoni M, Poli D, Bernocchi G, Manzo L. Perinatal co-exposure to methylmercury and PCB153 or PCB126 in rats alters the cerebral cholinergic muscarinic receptors at weaning and puberty. Toxicology 2007; 238:34-48. [PMID: 17618726 DOI: 10.1016/j.tox.2007.05.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2007] [Revised: 05/10/2007] [Accepted: 05/14/2007] [Indexed: 10/23/2022]
Abstract
In the last few decades, combined exposure to methylmercury (MeHg) and polychlorinated biphenyls (PCBs) from fish and seafood, and their potentially interactive effects on neurodevelopment, have been giving increasing cause for concern. We examined the combined effects of MeHg and either a non-dioxin PCB (PCB153) or a dioxin-like PCB (PCB126) congener on the developing brain cholinergic muscarinic receptors (MRs). These receptors are known to play a major role in many central functions including higher cognitive processes and the modulation of extrapyramidal motor activity. MRs in pup rat brains diminished following prenatal and lactational exposure, from gestational day [GD]7 to postnatal day [PND]21, to MeHg (0.5mg/kgbodyweight[bw]/day), PCB153 (5mg/kgbw/day), and PCB126 (100ng/kg/day), alone or in combination. Total MR density, as well as M1, M2, and M3 receptor subtypes of the weanling and pubertal rats, were affected in a brain-area-, gender-, time- and compound-dependent fashion. MeHg decreased (by 15-20%) the total MR density in a delayed (PND36) manner in the cerebral cortex of both genders, and early (at weaning) in the cerebellum of both genders, with the effect lasting until puberty (in males only). MeHg decreased the ACh M1- and M3-immunopositive neurons in the cerebral cortex and also increased the M2-immunopositive Bergmann glia in the cerebellum. PCB153 also induced a delayed (PND36) decrease (of 20%) in total MR number in the cerebellum of the male offspring and in the cerebral cortex of both genders. The latter effect was coupled with a decrease in ACh M1- and ACh M3-immunopositive neuron populations. PCB126 decreased (by 30-40%) total MR density in a gender-dependent manner, males being more sensitive than females. The effect was evident early (at PND21) and lasted until puberty in the cerebellum, while it was observed later (at PND36) in the cerebral cortex. The M1 and M3 receptors were similarly affected by PCB126. Co-exposure to MeHg and either PCB153 or PCB126 had the same effect on the cerebral MRs as exposure to each compound alone. The results rule out additive or synergistic interactions between MeHg and PCB153 or PCB126 on MRs in the brain areas examined. Some early-onset changes persisted until puberty, while other modifications became manifest only at the advanced time point (PND36), when the brain levels of total Hg, PCB153, and PCB126 had declined. These data support the ability of MeHg and PCBs to induce delayed neurotoxicity after developmental exposure.
Collapse
Affiliation(s)
- Teresa Coccini
- IRCCS Salvatore Maugeri Foundation, Toxicology Division, Institute of Pavia, Italy.
| | | | | | | | | | | | | |
Collapse
|
40
|
Coccini T, Randine G, Castoldi AF, Acerbi D, Manzo L. Methylmercury interaction with lymphocyte cholinergic muscarinic receptors in developing rats. ENVIRONMENTAL RESEARCH 2007; 103:229-37. [PMID: 16808911 DOI: 10.1016/j.envres.2006.05.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2006] [Revised: 05/10/2006] [Accepted: 05/17/2006] [Indexed: 05/10/2023]
Abstract
Cerebral cholinergic muscarinic receptors (MR) have been suggested as one of the sensitive biochemical endpoints of the central nervous system altered by developmental exposure to the widespread seafood contaminant methylmercury (MeHg). In adult rats, MeHg has been shown to alter MR binding both in the brain and lymphocytes, supporting the use of MR in blood cells as a surrogate marker of CNS changes. The effects of MeHg have been evaluated on rat lymphocyte MR binding (using [3H]QNB as specific muscarinic ligand) in vivo (after perinatal exposure) and in vitro. For comparison, in vitro studies were also performed on human lymphocytes. Exposure to 1 mg MeHg/kg/day during pregnancy and lactation (from GD7 to PND7) significantly enhanced lymphocyte MR density in both adult and young rats 21 days after delivery, with a more pronounced effect in the mothers (B(max) increase of 139%) than in the male offspring (+49%) and female offspring (+73%) as compared with their respective controls (33+/-4, 41+/-8, and 37+/-4 fmol/million cells), in accordance with the higher Hg levels detected in the adult blood (11.3+/-2.2 microg/mL) than in pups (1.3+/-0.4 microg/L in both genders). A lower MeHg dose (0.5 mg/kg/day) was without any effect on lymphocyte MRs. In in vitro studies, MeHg was an almost equipotent inhibitor of (3)H-QNB binding to rat and human lymphocyte MRs (IC50 values were 4.1+/-0.29, 5.2+/-0.51, and 5.0+/-0.9 microM for total rat lymphocytes, rat T lymphocytes, and total human lymphocytes, respectively). Notably, the IC50 values for MeHg to lymphocyte MRs were comparable to the Hg levels reached in blood (5-50 microM) of the PND21 rats exposed to MeHg. The finding that the MR binding is a target for the effects of MeHg in peripheral blood cells is in accordance with our previous data in brain [Coccini et al., 2006. Effects of developmental co-exposure to methylmercury and 2,2',4,4',5,5'-hexachlorobiphenyl (PCB153) on cholinergic muscarinic receptors in rat brain. Neurotoxicology, in press], and supports the use of this peripheral endpoint as a biomarker of MeHg-induced cerebral muscarinic alterations. The similarity of MeHg IC50 binding data between human and rat in peripheral tissues suggests the possible application of such biomarker to humans exposed to environmental chemicals.
Collapse
Affiliation(s)
- Teresa Coccini
- Toxicology Division, Salvatore Maugeri Foundation IRCCS, Institute of Pavia, Via Maugeri, 10, 27100 Pavia, Italy.
| | | | | | | | | |
Collapse
|
41
|
Basu N, Scheuhammer AM, Bursian SJ, Elliott J, Rouvinen-Watt K, Chan HM. Mink as a sentinel species in environmental health. ENVIRONMENTAL RESEARCH 2007; 103:130-44. [PMID: 16716289 DOI: 10.1016/j.envres.2006.04.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2006] [Revised: 03/29/2006] [Accepted: 04/03/2006] [Indexed: 05/09/2023]
Abstract
The concept of "sentinel species" is important in the environmental health sciences because sentinel species can provide integrated and relevant information on the types, amounts, availability, and effects of environmental contaminants. Here we discuss the use of mink (Mustela vison) as a sentinel organism by reviewing the pertinent literature from exposure- and effects-based studies. The review focuses on mercury (Hg) and polychlorinated biphenyls (PCBs), as they are persistent, ubiquitous, and bioaccumulative contaminants of concern to both humans and wildlife. Mink are widely distributed, abundant, and regularly trapped in temperate, aquatic ecosystems, and this makes them an excellent model to address issues in environmental pollution on both temporal and spatial scales. As a high-trophic-level, piscivorous mammal, mink can bioaccumulate appreciable concentrations of certain pollutants and have been shown to be sensitive to their toxic effects. The husbandry and life history of mink are well understood, and this has permitted controlled dosing experiments to be conducted using animals reared in captivity. These manipulative studies have yielded important quantitative information on exposure-response relationships and benchmarks of adverse health effects, and have also allowed the cellular mechanisms underlying toxic effects to be explored. Furthermore, the data accrued from the laboratory continue to validate observations made in the field. Research derived from mink can bridge and integrate multiple disciplines, and the information collected from this species has allowed environmental health scientists to better understand and characterize pollution effects on ecosystems.
Collapse
Affiliation(s)
- Niladri Basu
- National Wildlife Research Center, Canadian Wildlife Service, Environment Canada, Ottawa, Ontario, Canada.
| | | | | | | | | | | |
Collapse
|
42
|
Pabello N, Lawrence D. Neuroimmunotoxicology: Modulation of neuroimmune networks by toxicants. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.cnr.2006.04.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
43
|
Basu N, Scheuhammer AM, Rouvinen-Watt K, Grochowina N, Klenavic K, Evans RD, Chan HM. Methylmercury Impairs Components of the Cholinergic System in Captive Mink (Mustela vison). Toxicol Sci 2006; 91:202-9. [PMID: 16446290 DOI: 10.1093/toxsci/kfj121] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The effects of methylmercury (MeHg) on components of the cholinergic system were evaluated in captive mink (Mustela vison). Cholinergic parameters were measured in brain regions (occipital cortex, cerebellum, brain stem, basal ganglia) and blood (whole blood, plasma, serum) following an 89-day exposure to MeHg at dietary concentrations of 0, 0.1, 0.5, 1, and 2 ppm (n = 12 animals per treatment). There were no effects of MeHg on brain choline acetyltransferase, acetylcholine, and choline transporter. However, significantly higher densities of muscarinic cholinergic receptors, as assessed by 3H-quinuclidinyl benzilate binding, were measured in the occipital cortex (30.2 and 39.0% higher in the 1 and 2 ppm groups, respectively), basal ganglia (67.5 and 69.1% higher in the 0.5 and 1 ppm groups, respectively), and brain stem (64.4% higher in the 0.5 ppm group), compared to nonexposed controls. The calculated positive relationship between MeHg exposure and muscarinic cholinergic receptor levels in this dosing study were consistent with observations in wild mink. There were no MeHg-related effects on blood cholinesterase (ChE) activity, but ChE activity was significantly higher in the occipital cortex (17.0% in the 1 ppm group) and basal ganglia (34.1% in the 0.5 ppm group), compared to nonexposed controls. The parallel increases in muscarinic cholinergic receptor levels and ChE activity following MeHg exposure highlight the autoregulatory nature of cholinergic neurotransmission. In conclusion, these laboratory data support findings from wild mink and demonstrate that ecologically relevant exposures to MeHg (i.e., 0.5 ppm in diet) have the potential to alter the cholinergic system in specific brain regions.
Collapse
Affiliation(s)
- Niladri Basu
- Department of Natural Resource Sciences, McGill University, Ste. Anne de Bellevue, Quebec, Canada, H9X 3V9
| | | | | | | | | | | | | |
Collapse
|
44
|
Castoldi AF, Coccini T, Randine G, Hernández-Viadel M, Felipo V, Manzo L. Lymphocyte cytochrome c oxidase, cyclic GMP and cholinergic muscarinic receptors as peripheral indicators of carbon monoxide neurotoxicity after acute and repeated exposure in the rat. Life Sci 2005; 78:1915-24. [PMID: 16288783 DOI: 10.1016/j.lfs.2005.08.032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Accepted: 08/27/2005] [Indexed: 11/21/2022]
Abstract
Changes in cerebral cytochrome oxidase (COX) activity, nitric oxide (NO)-cyclic GMP (cGMP) pathway and cholinergic muscarinic receptors (MRs) have been reported in rodents acutely exposed to carbon monoxide (CO). These endpoints measurable in lymphocytes may serve as peripheral markers of CO neurotoxicity. The early and delayed effects of repeated and acute in vivo CO inhalation were investigated on COX activity, cGMP formation and MR binding in rat brain and lymphocytes to assess whether each endpoint was similarly affected both centrally and peripherally. Male Wistar rats either inhaled 500 ppm CO, 6 h/day, 5 days/week, 4 weeks (repeated exposure) or 2,400 ppm, 1 h (single exposure). Neither treatment altered brain or lymphocyte COX activity 1 and 7 days post-treatment. Also ineffective were repeated and acute CO treatments towards (3)H-quinuclidinyl benzilate (QNB) binding to MRs in cerebral cortex, hippocampus, striatum, cerebellum (respective controls, mean+/-S.D.: 171 +/- 45, 245 +/- 53, 263 +/- 14 and 77 +/- 7 fmol/mg protein) and lymphocytes (24 +/- 10 fmol/million cells) at the same time points. In lymphocytes control cGMP levels averaged 1.98 +/- 0.99 pmol/mg protein under basal conditions, and 3.94 +/- 0.55 pmol/mg protein after NO-stimulation. One day after chronic treatment cessation, the CO-treated group displayed about a 50% decrease in both basal and NO-stimulated cGMP values, which persisted up to 7 days after, compared to air-exposed rats. Acutely, CO caused a delayed enhancement (+140%) of NO-induced activation of soluble guanylate cyclase. The finding that the NO-cGMP pathway is a target for the delayed effects of CO in peripheral blood cells is in accordance with our data in brain [Hernández-Viadel, M., Castoldi, A.F., Coccini, T., Manzo, L., Erceg, S., Felipo, V., 2004. In vivo exposure to carbon monoxide causes delayed impairment of activation of soluble guanylate cyclase by nitric oxide in rat brain cortex and cerebellum. Journal of Neurochemistry 89, 1,157-1,165], and supports the use of this peripheral endpoint as a biomarker of CO central effects.
Collapse
Affiliation(s)
- Anna F Castoldi
- Toxicology Division, IRCCS Salvatore Maugeri Foundation, Institute of Pavia, Via Ferrata 8, 27100 Pavia, Italy.
| | | | | | | | | | | |
Collapse
|
45
|
Zahir F, Rizwi SJ, Haq SK, Khan RH. Low dose mercury toxicity and human health. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2005; 20:351-60. [PMID: 21783611 DOI: 10.1016/j.etap.2005.03.007] [Citation(s) in RCA: 595] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2004] [Accepted: 03/20/2005] [Indexed: 05/02/2023]
Abstract
Post Minamata incident there has been awareness about mercury toxicity even among the general public. Previous researches contributed a vast amount of data regarding acute mercury exposure, but gradually information about the low dose [Ninomiya, T., Ohmori, H., Hashimoto, K., Tsuruta, K., Ekino, S., 1995. Expansion of methylmercury poisoning outside minamata: an epidemiological study on chronic methylmercury poisoninig outside of Minamata. Environ. Res. 70 (1) 47-50; Lebel, J., Mergler, D., Lucotte, M., Amorim, M., Dolbec, J., Miranda, D., Arantes, G., Rheault, I., Pichet, P., 1996. Evidence of early nervous system dysfunction in Amazonian populations exposed to low-levels of methylmercury. Neurotoxicology 17 (1) 157-167] of mercury toxicity has been trickling in. With mercury contaminating rain-, ground- and sea-water no one is safe. Polluted water leads to mercury laced fish, meat and vegetable. In aquatic environments, inorganic mercury is microbiologically transformed into lipophilic organic compound 'methylmercury'. This transformation makes mercury more prone to biomagnification in food chains. Consequently, populations with traditionally high dietary intake of food originating from fresh or marine environment have highest dietary exposure to mercury. Extensive research done on locals across the globe have already established this, persons who routinely consume fish or a particular species of fish are at an increased risk of methylmercury poisoning. The easy access of the toxicant to man through multiple pathways air, water, food, cosmetic products and even vaccines increase the exposure. Foetus and children are more susceptible towards mercury toxicity. Mothers consuming diet containing mercury pass the toxicant to foetus and to infants through breast milk. Decreased performance in areas of motor function and memory has been reported among children exposed to presumably safe mercury levels. Similarly, disruption of attention, fine motor function and verbal memory was also found in adults on exposure to low mercury levels. It is an occupational hazard for dental staff, chloralkali factory workers and goldminers, etc. Mercury has been found to be a causative agent of various sorts of disorders, including neurological, nephrological, immunological, cardiac, motor, reproductive and even genetic. Recently heavy metal mediated toxicity has been linked to diseases like Alzeihemer's, Parkinson's, Autism, Lupus, Amyotrophic lateral sclerosis, etc. Besides this, it poses danger to wildlife. Therefore, it becomes imperative to spread the information regarding the threat of mercury exposure amongst the scientists and masses.
Collapse
Affiliation(s)
- Farhana Zahir
- Interdisciplinary Brain Research Centre, JN Medical College, AMU, Aligarh, U.P., India
| | | | | | | |
Collapse
|
46
|
Basu N, Scheuhammer A, Grochowina N, Klenavic K, Evans D, O'Brien M, Chan HM. Effects of mercury on neurochemical receptors in wild river otters (Lontra canadensis). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2005; 39:3585-91. [PMID: 15952362 DOI: 10.1021/es0483746] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Fish-eating wildlife, such as river otters (Lontra canadensis), accumulate mercury (Hg) at concentrations known to impair animal behavior, but few studies have explored the underlying biochemical changes that precede clinical neurotoxicity. The objective of this study was to determine if Hg exposure can be related to concentrations of neurochemical receptors in river otters. River otter carcasses (n = 66) were collected in Ontario and Nova Scotia (Canada) by local trappers in 2002-2004. Concentrations of Hg (total and organic) were measured in the cerebral cortex and cerebellum. Saturation binding curves for the cholinergic muscarinic acetylcholine (mACh) receptor and dopamine-2 (D2) receptor were completed for each animal to calculate receptor density (Bmax) and ligand affinity (Kd). Negative correlations were found between concentrations of Hg and mACh receptor Bmax (r(total) Hg = -0.458, r(inorganic) Hg = -0.454, r(organic) Hg = -0.443) in the cerebral cortex. A negative correlation was also found between concentrations of total Hg and D2 receptor Bmax (r = -0.292) in the cerebral cortex. These results suggest that neurochemical receptors may prove useful as novel biomarkers of Hg exposure and neurotoxic effects in wildlife. Given the importance of cholinergic and dopaminergic systems in animal physiology, the ecological implications of these changes need to be investigated.
Collapse
Affiliation(s)
- Niladri Basu
- Department of Natural Resource Sciences, Centerfor Indigenous Peoples' Nutrition and Environment (CINE), and School of Dietetics and Human Nutrition, McGill University, Saint Anne de Bellevue, Quebec, Canada H9X 3V9
| | | | | | | | | | | | | |
Collapse
|
47
|
Vezér T, Papp A, Kurunczi A, Párducz A, Náray M, Nagymajtényi L. Behavioral and neurotoxic effects seen during and after subchronic exposure of rats to organic mercury. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2005; 19:785-796. [PMID: 21783556 DOI: 10.1016/j.etap.2004.12.045] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Young adult male Wistar rats (24/group) were treated for 5 weeks with methyl mercury(II)chloride (corresponding to 0.5 and 2.0mgHg°/kg b.w., control: distilled water) by gavage, followed by a 19 weeks post-treatment period. Spontaneous motility, psychomotor performance and sensorimotor gating was repeatedly tested, electrophysiological recordings done, in the rats throughout the whole experiment. Decreased horizontal open field activity, reduced number of "noise positive" startle responses, as well as increase of startle response onset latency and peak time, and decrease of peak amplitude, was seen in the treated animals. Most changes disappeared in the post-treatment period. In the spontaneous cortical and hippocampal activity, altered distribution of the frequency bands was seen after 5 weeks of treatment but not at the end of the post-treatment period. Hippocampal population spikes in the treated animals were depressed and showed less potentiation, which effect was still present 19 weeks after finishing the treatment. The duration of the sensory cortical evoked potentials was shorter than in the controls. In the treated rats, tyrosine hydroxylase-immunoreactive boutons in the substantia nigra pars reticulata were shrunk; blood and brain Hg levels were significantly higher and decreased only slowly. Considering the continuous presence of low levels of mercurials in the human environment, effects of this kind may be supposed as the background of some human neurobehavioral abnormalities.
Collapse
Affiliation(s)
- Tünde Vezér
- Department of Public Health, University of Szeged, H-6720 Szeged, Dóm tér 10, Hungary
| | | | | | | | | | | |
Collapse
|
48
|
Coccini T, Randine G, Castoldi AF, Balloni L, Baiardi P, Manzo L. Lymphocyte muscarinic receptors and platelet monoamine oxidase-B as biomarkers of CNS function: effects of age and gender in healthy humans. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2005; 19:715-720. [PMID: 21783547 DOI: 10.1016/j.etap.2004.12.042] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Lymphocyte cholinergic muscarinic receptors (MRs) and platelet monoamine oxidase-B (MAO-B) activity are considered surrogate markers of the same parameters in the central nervous system. Lymphocyte MR binding and platelet MAO-B activity were measured in a consistent number of healthy human adults and analysed according to gender and age. The mean value±S.D. of MR binding neither differed between males (12.2±10.0fmol/10(6)cells, range: 0.5-37.9, n=86) and females (10.7±9.7fmol/10(6)cells, range: 0.5-39.7, n=69) nor among age groups. MAO-B activity was significantly higher in women (geometric mean: 11.3nmol/mgprotein/h, with 65% of values from 7.3 to 17.6; n=43), than in men (7.7nmol/mgprotein/h, with 65% of values from 4.5 to 13; n=95). Males aged 56-66 years displayed a higher, though not statistically significant, basal enzyme activity than younger subjects. Altogether these data indicate gender-related differences in MAO activity, but not in MR binding, and inter-individual differences in the basal values of both peripheral blood markers in healthy subjects.
Collapse
Affiliation(s)
- Teresa Coccini
- Toxicology Division, Institute of Pavia, IRCCS Salvatore Maugeri Foundation, Via Ferrata 8, 27100 Pavia, Italy
| | | | | | | | | | | |
Collapse
|
49
|
Limke TL, Heidemann SR, Atchison WD. Disruption of Intraneuronal Divalent Cation Regulation by Methylmercury: Are Specific Targets Involved in Altered Neuronal Development and Cytotoxicity in Methylmercury Poisoning? Neurotoxicology 2004; 25:741-60. [PMID: 15288506 DOI: 10.1016/j.neuro.2003.12.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2003] [Accepted: 12/15/2003] [Indexed: 10/26/2022]
Abstract
Methylmercury is an environmental contaminant which causes relatively specific degeneration of the granular layer of the cerebellum, despite its ability to bind thiol groups in proteins of all cell types. The mechanisms underlying the specific targeting of cells during MeHg poisoning may depend on specific receptors and other targets related to divalent cation homeostasis, particularly intracellular calcium (Ca(2+)(i) signaling. MeHg disrupts Ca(2+)(i) homeostasis in a number of neuronal models, including cerebellar granule cells in primary culture, and contributes to MeHg-induced cell death, impaired synaptic function and disruption of neuronal development. Interestingly, the disruption of [Ca(2+)](i) regulation occurs through specific pathways which affect Ca(2+) regulation by organelles, particularly mitochondria and the smooth endoplasmic reticulum (SER). Cholinergic pathways which affect [Ca(2+)](i) signaling also appear to be critical targets, particularly muscarinic acetylcholine (ACh) receptors which are linked to Ca(2+) release through inositol-1,4,5-triphosphate (IP(3)) receptors. [Ca(2+)](i) dysregulation may also underlie observed alterations in cerebellar neuron development through interaction with specific target(s) in the developing axon. In this review, we examine the hypothesis that MeHg affects specific targets to cause disruption of neuronal development and cell death.
Collapse
Affiliation(s)
- Tobi L Limke
- Department of Pharmacology and Toxicology, Institute for Environmental Toxicology, Michigan State University, B-331 Life Sciences Building, East Lansing, MI 48824-1317, USA
| | | | | |
Collapse
|
50
|
Fonnum F, Lock EA. The contributions of excitotoxicity, glutathione depletion and DNA repair in chemically induced injury to neurones: exemplified with toxic effects on cerebellar granule cells. J Neurochem 2004; 88:513-31. [PMID: 14720201 DOI: 10.1046/j.1471-4159.2003.02211.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Six chemicals, 2-halopropionic acids, thiophene, methylhalides, methylmercury, methylazoxymethanol (MAM) and trichlorfon (Fig. 1), that cause selective necrosis to the cerebellum, in particular to cerebellar granule cells, have been reviewed. The basis for the selective toxicity to these neurones is not fully understood, but mechanisms known to contribute to the neuronal cell death are discussed. All six compounds decrease cerebral glutathione (GSH), due to conjugation with the xenobiotic, thereby reducing cellular antioxidant status and making the cells more vulnerable to reactive oxygen species. 2-Halopropionic acids and methylmercury appear to also act via an excitotoxic mechanism leading to elevated intracellular Ca2+, increased reactive oxygen species and ultimately impaired mitochondrial function. In contrast, the methylhalides, trichlorfon and MAM all methylate DNA and inhibit O6-guanine-DNA methyltransferase (OGMT), an important DNA repair enzyme. We propose that a combination of reduced antioxidant status plus excitotoxicity or DNA damage is required to cause cerebellar neuronal cell death with these chemicals. The small size of cerebellar granule cells, the unique subunit composition of their N-methyl-d-aspartate (NMDA) receptors, their low DNA repair ability, low levels of calcium-binding proteins and vulnerability during postnatal brain development and distribution of glutathione and its conjugating and metabolizing enzymes are all important factors in determining the sensitivity of cerebellar granule cells to toxic compounds.
Collapse
Affiliation(s)
- F Fonnum
- Norwegian Defence Research Establishment, Division for Protection and Material, Kjeller, Norway.
| | | |
Collapse
|