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Bottini CLJ, MacDougall-Shackleton SA. Methylmercury effects on avian brains. Neurotoxicology 2023; 96:140-153. [PMID: 37059311 DOI: 10.1016/j.neuro.2023.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Revised: 04/03/2023] [Accepted: 04/11/2023] [Indexed: 04/16/2023]
Abstract
Methylmercury (MeHg) is a concerning contaminant due to its ubiquity and harmful effects on organisms. Although birds are important models in the neurobiology of vocal learning and adult neuroplasticity, the neurotoxic effects of MeHg are less understood in birds than mammals. We surveyed the literature on MeHg effects on biochemical changes in the avian brain. Publication rates of papers related to neurology and/or birds and/or MeHg increased with time and can be linked with historical events, regulations, and increased understanding of MeHg cycling in the environment. However, publications on MeHg effects on the avian brain remain relatively low across time. The neural effects measured to evaluate MeHg neurotoxicity in birds changed with time and researcher interest. The measures most consistently affected by MeHg exposure in birds were markers of oxidative stress. NMDA, acetylcholinesterase, and Purkinje cells also seem sensitive to some extent. MeHg exposure has the potential to affect most neurotransmitter systems but more studies are needed for validation in birds. We also review the main mechanisms of MeHg-induced neurotoxicity in mammals and compare it to what is known in birds. The literature on MeHg effects on the avian brain is limited, preventing full construction of an adverse outcome pathway. We identify research gaps for taxonomic groups such as songbirds, and age- and life-stage groups such as immature fledgling stage and adult non-reproductive life stage. In addition, results are often inconsistent between experimental and field studies. We conclude that future neurotoxicological studies of MeHg impacts on birds need to better connect the numerous aspects of exposure from molecular physiological effects to behavioural outcomes that would be ecologically or biologically relevant for birds, especially under challenging conditions.
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Affiliation(s)
- Claire L J Bottini
- University of Western Ontario, Department of Biology, 1151 Richmond St., London Ontario, N6A 5B7; Advanced Facility for Avian Research, University of Western Ontario, London, Ontario, Canada.
| | - Scott A MacDougall-Shackleton
- Advanced Facility for Avian Research, University of Western Ontario, London, Ontario, Canada; University of Western Ontario, Department of Psychology, 1151 Richmond St., London Ontario, N6A 5C2
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2
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Sato M, Toyama T, Kim MS, Lee JY, Hoshi T, Miura N, Naganuma A, Hwang GW. Increased putrescine levels due to ODC1 overexpression prevents mitochondrial dysfunction-related apoptosis induced by methylmercury. Life Sci 2020; 256:118031. [PMID: 32615186 DOI: 10.1016/j.lfs.2020.118031] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 06/25/2020] [Accepted: 06/27/2020] [Indexed: 12/23/2022]
Abstract
AIMS We had previously reported that addition of putrescine to the culture medium was reported to reduce methylmercury toxicity in C17.2 neural stem cells. Here, we have examined the inhibition of methylmercury-induced cytotoxicity by putrescine using ODC1-overexpressing C17.2 cells. MATERIALS AND METHODS We established stable ODC1-overexpressing C17.2 cells and evaluated methylmercury-induced apoptosis by examining the TUNEL assay and cleaved caspase-3 levels. Mitochondria-mediated apoptosis was also evaluated by reduction of mitochondrial membrane potential and recruitment of Bax and Bak to the mitochondria. KEY FINDINGS ODC is encoded by ODC1 gene, and putrescine levels in ODC1-overexpressing cells were significantly higher than in control cells. Overexpression of ODC1 and addition of putrescine to the culture medium suppressed DNA fragmentation and caspase-3 activation, which are observed when apoptosis is induced by methylmercury. Moreover, mitochondrial dysfunction and reactive oxygen species (ROS) generation, caused by methylmercury, were also inhibited by the overexpression of ODC1 and putrescine; pretreatment with ODC inhibitor, however, promoted both ROS generation and apoptosis by methylmercury. Finally, we found that Bax and Bak, the apoptosis-promoting factors, to be increased in mitochondria, following methylmercury treatment, and the same was inhibited by overexpression of ODC1. These results suggest that overexpression of ODC1 may prevent mitochondria-mediated apoptosis by methylmercury via increase of putrescine levels. SIGNIFICANCE Our findings provide important clues to clarify mechanisms involved in the defense against methylmercury toxicity and suggest novel biological functions of putrescine.
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Affiliation(s)
- Masayuki Sato
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Takashi Toyama
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Min-Seok Kim
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan; Inhalation Toxicology Research Group, Korea Institute of Toxicology, 30, Baekhak1-gil Jeongeup-si, Jeollabuk-do 56212, Republic of Korea
| | - Jin-Yong Lee
- Laboratory of Pharmaceutical Health Sciences, School of Pharmacy, Aichi Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya 464-8650, Japan
| | - Takayuki Hoshi
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Nobuhiko Miura
- Laboratory of Environmental and Molecular Toxicology, Yokohama University of Pharmacy, 601 Matano-cho, Totsuka-ku, Yokohama, Kanagawa 245-0066, Japan
| | - Akira Naganuma
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Gi-Wook Hwang
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan; Laboratory of Environmental and Health Sciences, Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan.
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3
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Ramos A, Dos Santos MM, de Macedo GT, Wildner G, Prestes AS, Masuda CA, Dalla Corte CL, Teixeira da Rocha JB, Barbosa NV. Methyl and Ethylmercury elicit oxidative stress and unbalance the antioxidant system in Saccharomyces cerevisiae. Chem Biol Interact 2020; 315:108867. [PMID: 31672467 DOI: 10.1016/j.cbi.2019.108867] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 10/07/2019] [Accepted: 10/21/2019] [Indexed: 11/19/2022]
Abstract
Methylmercury (MeHg) and Ethylmercury (EtHg) are toxic to the central nervous system. Human exposure to MeHg and EtHg results mainly from the consumption of contaminated fish and thimerosal-containing vaccines, respectively. The mechanisms underlying the toxicity of MeHg and EtHg are still elusive. Here, we compared the toxic effects of MeHg and EtHg in Saccharomyces cerevisiae (S. cerevisiae) emphasizing the involvement of oxidative stress and the identification of molecular targets from antioxidant pathways. Wild type and mutant strains with deleted genes for antioxidant defenses, namely: γ-glutamylcysteine synthetase, glutathione peroxidase, catalase, superoxide dismutase, mitochondrial peroxiredoxin, cytoplasmic thioredoxin, and redox transcription factor Yap1 were used to identify potential pathways and proteins from cell redox system targeted by MeHg and EtHg. MeHg and EtHg inhibited cell growth, decreased membrane integrity, and increased the granularity and production of reactive species (RS) in wild type yeast. The mutants were predominantly less tolerant of mercurial than wild type yeast. But, as the wild strain, mutants exhibited higher tolerance to MeHg than EtHg. Our results indicate the involvement of oxidative stress in the cytotoxicity of MeHg and EtHg and reinforce S. cerevisiae as a suitable model to explore the mechanisms of action of electrophilic toxicants.
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Affiliation(s)
- Angelica Ramos
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Matheus M Dos Santos
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Gabriel T de Macedo
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Guilherme Wildner
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Alessandro S Prestes
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Claudio A Masuda
- Instituto de Bioquímica Médica Leopoldo De Meis, Universidade Federal do Rio de Janeiro, RJ, Brazil
| | | | | | - Nilda V Barbosa
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.
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4
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Nishimura A, Shimoda K, Tanaka T, Toyama T, Nishiyama K, Shinkai Y, Numaga-Tomita T, Yamazaki D, Kanda Y, Akaike T, Kumagai Y, Nishida M. Depolysulfidation of Drp1 induced by low-dose methylmercury exposure increases cardiac vulnerability to hemodynamic overload. Sci Signal 2019; 12:12/587/eaaw1920. [DOI: 10.1126/scisignal.aaw1920] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Akiyuki Nishimura
- Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences (NINS), Okazaki 444-8787, Japan
- National Institute for Physiological Sciences (NIPS), NINS, Okazaki 444-8787, Japan
| | - Kakeru Shimoda
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences (NINS), Okazaki 444-8787, Japan
- National Institute for Physiological Sciences (NIPS), NINS, Okazaki 444-8787, Japan
- SOKENDAI (School of Life Science, Graduate University for Advanced Studies), Okazaki 444-8787, Japan
| | - Tomohiro Tanaka
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences (NINS), Okazaki 444-8787, Japan
- National Institute for Physiological Sciences (NIPS), NINS, Okazaki 444-8787, Japan
- Faculty of Medicine, University of Tsukuba, Tsukuba 305-8575, Japan
| | - Takashi Toyama
- National Institute for Physiological Sciences (NIPS), NINS, Okazaki 444-8787, Japan
| | - Kazuhiro Nishiyama
- Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Yasuhiro Shinkai
- Center for Novel Science Initiatives (CNSI), NINS, Tokyo 105-0001, Japan
| | - Takuro Numaga-Tomita
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences (NINS), Okazaki 444-8787, Japan
- National Institute for Physiological Sciences (NIPS), NINS, Okazaki 444-8787, Japan
- SOKENDAI (School of Life Science, Graduate University for Advanced Studies), Okazaki 444-8787, Japan
| | - Daiju Yamazaki
- Division of Pharmacology, National Institute of Health Sciences, Kanagawa, 210-9501, Japan
| | - Yasunari Kanda
- Division of Pharmacology, National Institute of Health Sciences, Kanagawa, 210-9501, Japan
| | - Takaaki Akaike
- Graduate School of Medicine, Tohoku University, Sendai 980-8575, Japan
| | - Yoshito Kumagai
- Center for Novel Science Initiatives (CNSI), NINS, Tokyo 105-0001, Japan
| | - Motohiro Nishida
- Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences (NINS), Okazaki 444-8787, Japan
- National Institute for Physiological Sciences (NIPS), NINS, Okazaki 444-8787, Japan
- SOKENDAI (School of Life Science, Graduate University for Advanced Studies), Okazaki 444-8787, Japan
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5
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Effects of methyl mercury on the activity and gene expression of mouse Langerhans islets and glucose metabolism. Food Chem Toxicol 2016; 93:119-28. [DOI: 10.1016/j.fct.2016.05.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 04/29/2016] [Accepted: 05/06/2016] [Indexed: 01/01/2023]
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Affiliation(s)
- Ahmed E Abdel Moneim
- Department of Zoology and Entomology, Faculty of Science, Helwan University, Cairo, Egypt
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7
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Vergilio C, Carvalho C, Melo E. Mercury-induced dysfunctions in multiple organelles leading to cell death. Toxicol In Vitro 2015; 29:63-71. [DOI: 10.1016/j.tiv.2014.09.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 09/03/2014] [Accepted: 09/06/2014] [Indexed: 01/26/2023]
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8
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Rusetskaya N, Borodulin V. Biological activity of selenorganic compounds at heavy metal salts intoxication. ACTA ACUST UNITED AC 2015; 61:449-61. [DOI: 10.18097/pbmc20156104449] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Possible mechanisms of the antitoxic action of organoselenium compounds in heavy metal poisoning have been considered. Heavy metal toxicity associated with intensification of free radical oxidation, suppression of the antioxidant system, damage to macromolecules, mitochondria and the genetic material can cause apoptotic cell death or the development of carcinogenesis. Organic selenium compounds are effective antioxidants during heavy metal poisoning; they exhibit higher bioavailability in mammals than inorganic ones and they are able to activate antioxidant defense, bind heavy metal ions and reactive oxygen species formed during metal-induced oxidative stress. One of promising organoselenium compounds is diacetophenonyl selenide (DAPS-25), which is characterized by antioxidant and antitoxic activity, under conditions including heavy metal intoxication
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Affiliation(s)
- N.Y. Rusetskaya
- Razumovskiy Saratov State Medical University, Saratov, Russia
| | - V.B. Borodulin
- Razumovskiy Saratov State Medical University, Saratov, Russia
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9
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Watanabe J, Nakamachi T, Ohtaki H, Naganuma A, Shioda S, Nakajo S. Low dose of methylmercury (MeHg) exposure induces caspase mediated-apoptosis in cultured neural progenitor cells. J Toxicol Sci 2014; 38:931-5. [PMID: 24213013 DOI: 10.2131/jts.38.931] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Methylmercury (MeHg) is an environmental pollutant known to cause neurobehavioral defects, and it is especially toxic to the developing brain. In contrast to the adult, the developing brain consists of a large number of dividing neural progenitor cells (NPCs), which are vulnerable targets for MeHg toxicity. In a previous study, we showed that the embryonic NPCs from the telencephalon are more sensitive to MeHg than other neural cells. Here, we investigated the mechanism of cell death underlying MeHg toxicity. We observed that exposure of NPCs to MeHg caused DNA laddering in a dose- and time-dependent manner. Decreased pro-caspase3 and increased cleaved-caspase3 protein was observed 3-12 hours after incubation of NPCs with MeHg. Moreover, the caspase-inhibitor Z-VAD FMK significantly suppressed MeHg-induced cell death in a dose-dependent manner. These results suggest that environmentally relevant levels of MeHg exposure induce apoptosis in NPCs.
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Affiliation(s)
- Jun Watanabe
- Department of Anatomy, Showa University School of Medicine
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10
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Molecular mechanisms of methylmercury-induced cell death in human HepG2 cells. Food Chem Toxicol 2010; 48:1405-11. [PMID: 20226830 DOI: 10.1016/j.fct.2010.03.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 03/03/2010] [Accepted: 03/08/2010] [Indexed: 12/29/2022]
Abstract
Methylmercury (MeHg) has been suggested to exert cytotoxicity through multiple mechanisms, but the precise biochemical machinery has not been fully defined. This study was aimed at investigating the time-course (0-24h) effect of 2mg/L MeHg on cell death in human HepG2 cells. MeHg decreased cell viability in a time-dependent manner, which was concomitant with increased LDH leakage, reduced GSH levels, CAT activity and altered activity of the antioxidant enzymes GPx and GR at the longest times of incubation (16 and 24h). Activity of the detoxifying enzyme GST was also early enhanced (2h). Caspase-3 activity reached a maximum value at 8h and continued increased up to 24h. This feature was preceded by an enhancement in the caspase-9 activity (2h), whereas caspase-8 activity remained unchanged. MeHg early diminished Bcl-x(L)/Bcl-x(S) ratio and increased levels of the pro-apoptotic Bax and Bad. Moreover, MeHg-induced cytotoxicity was completely inhibited by the antioxidants (GSH and NAC) and notably by the mitochondrial complex I inhibitor rotenone, but not by the NADH oxidase inhibitor DPI. In summary, MeHg induced an oxidative stress responsible for apoptosis in HepG2 cells through direct activation of the caspase cascade and altered the cellular antioxidant and detoxificant enzymatic system to later provoke necrosis at later stages.
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11
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Correlations between gene expression and mercury levels in blood of boys with and without autism. Neurotox Res 2009; 19:31-48. [PMID: 19937285 PMCID: PMC3006666 DOI: 10.1007/s12640-009-9137-7] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 10/15/2009] [Accepted: 11/10/2009] [Indexed: 01/23/2023]
Abstract
Gene expression in blood was correlated with mercury levels in blood of 2- to 5-year-old boys with autism (AU) compared to age-matched typically developing (TD) control boys. This was done to address the possibility that the two groups might metabolize toxicants, such as mercury, differently. RNA was isolated from blood and gene expression assessed on whole genome Affymetrix Human U133 expression microarrays. Mercury levels were measured using an inductively coupled plasma mass spectrometer. Analysis of covariance (ANCOVA) was performed and partial correlations between gene expression and mercury levels were calculated, after correcting for age and batch effects. To reduce false positives, only genes shared by the ANCOVA models were analyzed. Of the 26 genes that correlated with mercury levels in both AU and TD boys, 11 were significantly different between the groups (P(Diagnosis*Mercury) ≤ 0.05). The expression of a large number of genes (n = 316) correlated with mercury levels in TD but not in AU boys (P ≤ 0.05), the most represented biological functions being cell death and cell morphology. Expression of 189 genes correlated with mercury levels in AU but not in TD boys (P ≤ 0.05), the most represented biological functions being cell morphology, amino acid metabolism, and antigen presentation. These data and those in our companion study on correlation of gene expression and lead levels show that AU and TD children display different correlations between transcript levels and low levels of mercury and lead. These findings might suggest different genetic transcriptional programs associated with mercury in AU compared to TD children.
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Ferraro L, Tomasini MC, Tanganelli S, Mazza R, Coluccia A, Carratù MR, Gaetani S, Cuomo V, Antonelli T. Developmental exposure to methylmercury elicits early cell death in the cerebral cortex and long-term memory deficits in the rat. Int J Dev Neurosci 2008; 27:165-74. [PMID: 19084587 DOI: 10.1016/j.ijdevneu.2008.11.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Revised: 11/05/2008] [Accepted: 11/12/2008] [Indexed: 01/24/2023] Open
Abstract
Experiments were performed to assess the neurotoxic effects induced by prenatal acute treatment with methylmercury on cortical neurons. To this purpose, primary neuronal cultures were obtained from cerebral cortex of neonatal rats born to dams treated with methylmercury (4 and 8 mg/kg by gavage) on gestational day 15, the developmental stage critical for cortical neuron proliferation. Prenatal exposure to methylmercury 8 mg/kg significantly reduced cell viability and caused either apoptotic or necrotic neuronal death. Moreover, this exposure level resulted in abnormal neurite outgrowth and retraction or collapse of some neurites, caused by a dissolution of microtubules. The severe and early cortical neuron damage induced by methylmercury 8 mg/kg treatment correlated with long term memory impairment, since adult rats (90 days of age) born to dams treated with this dose level showed a significant deficit in the retention performance when subjected to a passive avoidance task. Prenatal exposure to methylmercury 4 mg/kg significantly increased the neuronal vulnerability to a neurotoxic insult. This was determined by measuring the increment of chromatin condensation induced by glutamate, at a concentration (30 microM) able to induce an excitotoxic damage. This exposure level eliciting apoptotic death did not result in cognitive dysfunctions. In conclusion, the methylmercury-induced disruption of glutamate pathway during critical windows of brain development may interfere with cell fate and proliferation resulting in a more or less severe cortical lesions associated or not with loss of function later in life, depending on the exposure levels. Therefore, the early biochemical effects and long-term behavioral changes elicited by high methylmercury levels suggest that the developing brain is impaired in its ability to recover following toxic insult, and the initial effects on cortical neurons may lead to permanent cognitive dysfunctions.
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Affiliation(s)
- Luca Ferraro
- Department of Clinical and Experimental Medicine, University of Ferrara, Ferrara, Italy.
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13
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Bourdineaud JP, Bellance N, Bénard G, Brèthes D, Fujimura M, Gonzalez P, Marighetto A, Maury-Brachet R, Mormède C, Pédron V, Philippin JN, Rossignol R, Rostène W, Sawada M, Laclau M. Feeding mice with diets containing mercury-contaminated fish flesh from French Guiana: a model for the mercurial intoxication of the Wayana Amerindians. Environ Health 2008; 7:53. [PMID: 18959803 PMCID: PMC2584016 DOI: 10.1186/1476-069x-7-53] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2008] [Accepted: 10/29/2008] [Indexed: 05/27/2023]
Abstract
BACKGROUND In 2005, 84% of Wayana Amerindians living in the upper marshes of the Maroni River in French Guiana presented a hair mercury concentration exceeding the limit set up by the World Health Organization (10 microg/g). To determine whether this mercurial contamination was harmful, mice have been fed diets prepared by incorporation of mercury-polluted fish from French Guiana. METHODS Four diets containing 0, 0.1, 1, and 7.5% fish flesh, representing 0, 5, 62, and 520 ng methylmercury per g, respectively, were given to four groups of mice for a month. The lowest fish regimen led to a mercurial contamination pressure of 1 ng mercury per day per g of body weight, which is precisely that affecting the Wayana Amerindians. RESULTS The expression of several genes was modified with mercury intoxication in liver, kidneys, and hippocampus, even at the lowest tested fish regimen. A net genetic response could be observed for mercury concentrations accumulated within tissues as weak as 0.15 ppm in the liver, 1.4 ppm in the kidneys, and 0.4 ppm in the hippocampus. This last value is in the range of the mercury concentrations found in the brains of chronically exposed patients in the Minamata region or in brains from heavy fish consumers. Mitochondrial respiratory rates showed a 35-40% decrease in respiration for the three contaminated mice groups. In the muscles of mice fed the lightest fish-containing diet, cytochrome c oxidase activity was decreased to 45% of that of the control muscles. When mice behavior was assessed in a cross maze, those fed the lowest and mid-level fish-containing diets developed higher anxiety state behaviors compared to mice fed with control diet. CONCLUSION We conclude that a vegetarian diet containing as little as 0.1% of mercury-contaminated fish is able to trigger in mice, after only one month of exposure, disorders presenting all the hallmarks of mercurial contamination.
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Affiliation(s)
- Jean-Paul Bourdineaud
- Université de Bordeaux 1-CNRS UMR 5805, Station Marine d'Arcachon, place du Docteur Peyneau, Arcachon, 33120, France
| | - Nadège Bellance
- Physiopathologie Mitochondriale, Université Victor Segalen Bordeaux2-INSERM U688, 146 rue Léo Saignat, Bordeaux, 33076 cedex, France
| | - Giovani Bénard
- Physiopathologie Mitochondriale, Université Victor Segalen Bordeaux2-INSERM U688, 146 rue Léo Saignat, Bordeaux, 33076 cedex, France
| | - Daniel Brèthes
- Institut de Biochimie et Génétique Cellulaires, Université Victor Segalen Bordeaux 2, 1 rue Camille Saint-Saëns, Bordeaux, 33077 cedex, France
| | - Masatake Fujimura
- National Institute for Minamata Disease, Pathology Section, Department of Basic Medical Sciences, 4058-18 Hama, Minamata, Kumamoto 867-0008, Japan
| | - Patrice Gonzalez
- Université de Bordeaux 1-CNRS UMR 5805, Station Marine d'Arcachon, place du Docteur Peyneau, Arcachon, 33120, France
| | - Aline Marighetto
- Laboratoire de Neurosciences Cognitives, Université de Bordeaux 1-CNRS UMR 5106, Avenue des Facultés, Talence, 33405, France
| | - Régine Maury-Brachet
- Université de Bordeaux 1-CNRS UMR 5805, Station Marine d'Arcachon, place du Docteur Peyneau, Arcachon, 33120, France
| | - Cécile Mormède
- Laboratoire de Neurosciences Cognitives, Université de Bordeaux 1-CNRS UMR 5106, Avenue des Facultés, Talence, 33405, France
| | - Vanessa Pédron
- Université de Bordeaux 1-CNRS UMR 5805, Station Marine d'Arcachon, place du Docteur Peyneau, Arcachon, 33120, France
| | - Jean-Nicolas Philippin
- Laboratoire de Neurosciences Cognitives, Université de Bordeaux 1-CNRS UMR 5106, Avenue des Facultés, Talence, 33405, France
| | - Rodrigue Rossignol
- Physiopathologie Mitochondriale, Université Victor Segalen Bordeaux2-INSERM U688, 146 rue Léo Saignat, Bordeaux, 33076 cedex, France
| | - William Rostène
- Centre de Recherches Saint-Antoine, INSERM U732, Hôpital Saint-Antoine, 184 rue du Faubourg Saint-Antoine, Paris, 75571 cedex 12, France
| | - Masumi Sawada
- National Institute for Minamata Disease, Pathology Section, Department of Basic Medical Sciences, 4058-18 Hama, Minamata, Kumamoto 867-0008, Japan
| | - Muriel Laclau
- Université de Bordeaux 1-CNRS UMR 5805, Station Marine d'Arcachon, place du Docteur Peyneau, Arcachon, 33120, France
- Institut de Biochimie et Génétique Cellulaires, Université Victor Segalen Bordeaux 2, 1 rue Camille Saint-Saëns, Bordeaux, 33077 cedex, France
- Laboratoire de Neurosciences Cognitives, Université de Bordeaux 1-CNRS UMR 5106, Avenue des Facultés, Talence, 33405, France
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14
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Rana SVS. Metals and apoptosis: recent developments. J Trace Elem Med Biol 2008; 22:262-84. [PMID: 19013355 DOI: 10.1016/j.jtemb.2008.08.002] [Citation(s) in RCA: 239] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Revised: 07/01/2008] [Accepted: 07/11/2008] [Indexed: 12/20/2022]
Abstract
Apoptosis, also known as programmed cell death is a highly regulated and crucial process found in all multicellular organisms. It is not only implicated in regulatory mechanisms of cells, but has been attributed to a number of diseases, i.e. inflammation, malignancy, autoimmunity and neurodegeneration. A variety of toxins can induce apoptosis. Carcinogenic transition metals, viz. cadmium, chromium and nickel promote apoptosis along with DNA base modifications, strand breaks and rearrangements. Generation of reactive oxygen species, accumulation of Ca(2+), upregulation of caspase-3, down regulation of bcl-2, and deficiency of p-53 lead to arsenic-induced apoptosis. In the case of cadmium, metallothionein expression determines the choice between apoptosis and necrosis. Reactive oxygen species (ROS) and p53 contribute in apoptosis caused by chromium. Immuno suppressive mechanisms contribute in lead-induced apoptosis whereas in the case of mercury, p38 mediated caspase activation regulate apoptosis. Nickel kills the cells by apoptotic pathways. Copper induces apoptosis by p53 dependent and independent pathways. Beryllium stimulates the formation of ROS that play a role in Be-induced macrophage apoptosis. Selenium induces apoptosis by producing superoxide that activates p53. Thus, disorders of apoptosis may play a critical role in some of the most debilitating metal-induced afflictions including hepatotoxicity, renal toxicity, neurotoxicity, autoimmunity and carcinogenesis. An understanding of metal-induced apoptosis will be helpful in the development of preventive molecular strategies.
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Affiliation(s)
- Suresh Vir Singh Rana
- Toxicology Laboratory, Department of Zoology, Ch. Charan Singh University, Meerut, India.
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Madureira P, Cunha EM, Aguas AP. Acute depletion and recovery of peritoneal B-1 lymphocytes in BALB/c mice after a single injection of mercury chloride. Immunopharmacol Immunotoxicol 2007; 29:311-22. [PMID: 17849274 DOI: 10.1080/08923970701513518] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The acute toxicity of mercury (Hg) to B cells was studied in the peritoneal cavity of BALB/c mice, a coelomic space where both B-1 and B-2 subsets of B lymphocytes are present. Up to 24 hr after a single in situ Hg injection, the peritoneal cavity became virtually devoid of lymphocytes, particularly of the B-1 subset. Lymphocyte depletion was more severe for B than T cells. This depletion was associated with partial lymphocyte activation (CD69(+)) at 6 hr of treatment and it was due to apoptosis rather than to necrosis. Partial recovery of both B and T cells was observed in the peritoneal cavity 48 hr after the Hg injection. The phenomenon was followed by a second decrease in peritoneal lymphocytes 72 hr after Hg. Neutrophils that entered the peritoneal cavity because of the Hg injection were resistant to apoptosis. No significant changes in lymphocyte number or subpopulation were found in the spleen and thymus of the mice up to 72 hr after the Hg treatment. We concluded that B lymphocytes were severely affected by the toxic effects of Hg. Our data suggest that Hg-induced unbalance in the repertoire of B cells, of the B-1 subset in particular, may result later in the secretion of the high titres of pathogenic autoantibodies that are found in the Hg-induced lupus disorder of BALB/c mice.
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Affiliation(s)
- P Madureira
- Laboratory of Immunology Mário-Arala Chaves, Abel Salazar Institute for Biomedical Sciences, ICBAS, University of Porto, Porto, Portugal.
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16
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Burke K, Cheng Y, Li B, Petrov A, Joshi P, Berman R, Reuhl KR, DiCicco-Bloom E. Methylmercury elicits rapid inhibition of cell proliferation in the developing brain and decreases cell cycle regulator, cyclin E. Neurotoxicology 2006; 27:970-81. [PMID: 17056119 PMCID: PMC2013736 DOI: 10.1016/j.neuro.2006.09.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Revised: 08/21/2006] [Accepted: 09/08/2006] [Indexed: 01/12/2023]
Abstract
The developing brain is highly sensitive to methylmercury (MeHg). Still, the initial changes in cell proliferation that may contribute to long-term MeHg effects are largely undefined. Our previous studies with growth factors indicate that acute alterations of the G1/S-phase transition can permanently affect cell numbers and organ size. Therefore, we determined whether an environmental toxicant could also impact brain development with rapid (6-7h) effects on DNA synthesis and cell cycle machinery in neuronal precursors. In vivo studies in newborn rat hippocampus and cerebellum, two regions of postnatal neurogenesis, were followed by in vitro analysis of two precursor models, cortical and cerebellar cells, focusing on the proteins that regulate the G1/S transition. In postnatal day 7 (P7) pups, a single subcutaneous injection of MeHg (3microg/g) acutely (7h) decreased DNA synthesis in the hippocampus by 40% and produced long-term (2 weeks) reductions in total cell number, estimated by DNA quantification. Surprisingly, cerebellar granule cells were resistant to MeHg effects in vivo at comparable tissue concentrations, suggesting region-specific differences in precursor populations. In vitro, MeHg altered proliferation and cell viability, with DNA synthesis selectively inhibited at an early timepoint (6h) corresponding to our in vivo observations. Considering that G1/S regulators are targets of exogenous signals, we used a well-defined cortical cell model to examine MeHg effects on relevant cyclin-dependent kinases (CDK) and CDK inhibitors. At 6h, MeHg decreased by 75% levels of cyclin E, a cell cycle regulator with roles in proliferation and apoptosis, without altering p57, p27, or CDK2 nor levels of activated caspase 3. In aggregate, our observations identify the G1/S transition as an early target of MeHg toxicity and raise the possibility that cyclin E degradation contributes to both decreased proliferation and eventual cell death.
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Affiliation(s)
- Kelly Burke
- Department of Neuroscience & Cell Biology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey
| | - Yinghong Cheng
- Department of Neuroscience & Cell Biology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey
| | - Baogang Li
- Department of Neuroscience & Cell Biology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey
| | - Alex Petrov
- Department of Neuroscience & Cell Biology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey
| | - Pushkar Joshi
- Department of Neuroscience & Cell Biology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey
| | - Robert Berman
- Department of Neurological Surgery, University of California at Davis
| | | | - Emanuel DiCicco-Bloom
- Department of Neuroscience & Cell Biology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey
- Department of Pediatrics; Member of the Cancer Institute of New Jersey
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17
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Garg TK, Chang JY. Methylmercury causes oxidative stress and cytotoxicity in microglia: Attenuation by 15-deoxy-delta 12, 14-Prostaglandin J2. J Neuroimmunol 2006; 171:17-28. [PMID: 16225932 DOI: 10.1016/j.jneuroim.2005.09.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2005] [Accepted: 09/13/2005] [Indexed: 11/23/2022]
Abstract
Methylmercury (MeHg) causes severe neurological disorders in the central nervous system. This study focused on the effects of MeHg on microglia, macrophage-like cells that reside in the CNS important in neuro-immune interactions. The murine N9 microglial cell line was used in this set of study. MeHg caused reactive oxygen species generation, mitochondrial depolarization and aconitase inactivation, all of which were signs of cellular oxidative stress. MeHg greatly increased microglial IL-6 secretion despite the fact that it severely inhibited protein synthesis. The concentration that caused 50% cell death in 24 h was approximately 9 microM. Pretreatment of microglia with the prostaglandin derivative, 15-deoxy-delta 12, 14-Prostaglandin J2 attenuated MeHg induced cell death. The saving effect did not appear to be mediated through activation of peroxisome proliferator activated receptors (PPAR) since other agonists of these receptors did not prevent MeHg induced microglial death.
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Affiliation(s)
- Tarun K Garg
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, 4301 W. Markham St., Little Rock, AR 72205, USA
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Eisele K, Lang PA, Kempe DS, Klarl BA, Niemöller O, Wieder T, Huber SM, Duranton C, Lang F. Stimulation of erythrocyte phosphatidylserine exposure by mercury ions. Toxicol Appl Pharmacol 2005; 210:116-22. [PMID: 16137732 DOI: 10.1016/j.taap.2005.07.022] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2005] [Revised: 07/19/2005] [Accepted: 07/21/2005] [Indexed: 01/06/2023]
Abstract
The sequelae of mercury intoxication include induction of apoptosis. In nucleated cells, Hg2+-induced apoptosis involves mitochondrial damage. The present study has been performed to elucidate effects of Hg2+ in erythrocytes which lack mitochondria but are able to undergo apoptosis-like alterations of the cell membrane. Previous studies have documented that activation of a Ca2+-sensitive erythrocyte scramblase leads to exposure of phosphatidylserine at the erythrocyte surface, a typical feature of apoptotic cells. The erythrocyte scramblase is activated by osmotic shock, oxidative stress and/or energy depletion which increase cytosolic Ca2+ activity and/or activate a sphingomyelinase leading to formation of ceramide. Ceramide sensitizes the scramblase to Ca2+. The present experiments explored the effect of Hg2+ ions on erythrocytes. Phosphatidylserine exposure after mercury treatment was estimated from annexin binding as determined in FACS analysis. Exposure to Hg2+ (1 microM) indeed significantly increased annexin binding from 2.3+/-0.5% (control condition) to 23+/-6% (n=6). This effect was paralleled by activation of a clotrimazole-sensitive K+-selective conductance as measured by patch-clamp recordings and by transient cell shrinkage. Further experiments revealed also an increase of ceramide formation by approximately 66% (n=7) after challenge with mercury (1 microM). In conclusion, mercury ions activate a clotrimazole-sensitive K+-selective conductance leading to transient cell shrinkage. Moreover, Hg2+ increases ceramide formation. The observed mechanisms could similarly participate in the triggering of apoptosis in nucleated cells by Hg2+.
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Affiliation(s)
- Kerstin Eisele
- Department of Physiology, University of Tübingen, Germany
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