101
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Yang H, Xu Z, Liu W, Wei Y, Deng Y, Xu B. Effect of grape seed proanthocyanidin extracts on methylmercury-induced neurotoxicity in rats. Biol Trace Elem Res 2012; 147:156-64. [PMID: 22116679 DOI: 10.1007/s12011-011-9272-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Accepted: 11/13/2011] [Indexed: 10/15/2022]
Abstract
As a highly toxic environmental pollutant, methylmercury (MeHg) can cause neurotoxicity in animals and humans. Considering the antioxidant property of grape seed proanthocyanidin extracts (GSPE), this study was aimed to evaluate the effect of GSPE on MeHg-induced neurotoxicity in rats. Rats were exposed to MeHg by intraperitoneal injection (4, 12 μmol/kg, respectively) and GSPE was administered by gavage (250 mg/kg) 2 h later. After a 4-week treatment, phosphate-activated glutaminase, glutamine synthetase, glutathione peroxidase and superoxide dismutase activities, glutamate, glutamine, malondialdehyde and glutathione contents in cerebral cortex were measured. Reactive oxygen species (ROS) and apoptosis were also estimated in cells. The results showed that the MeHg-induced neurotoxicity was significantly attenuated. GSPE significantly decreased the production of ROS, counteracted oxidative damage and increased the antioxidants and antioxidant enzymes activities in rats prior to MeHg exposure. Moreover, the effects on the rate of apoptotic cells and the disturbance of glutamate homeostasis were correspondingly modulated. These observations highlighted the potential of GSPE in offering protection against MeHg-induced neurotoxicity.
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Affiliation(s)
- Haibo Yang
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, China
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102
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Fretham SJ, Caito S, Martinez-Finley EJ, Aschner M. Mechanisms and Modifiers of Methylmercury-Induced Neurotoxicity. Toxicol Res (Camb) 2012; 1:32-38. [PMID: 27795823 DOI: 10.1039/c2tx20010d] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The neurotoxic consequences of methylmercury (MeHg) exposure have long been known, however a complete understanding of the mechanisms underlying this toxicity is elusive. Recent epidemiological and experimental studies have provided many mechanistic insights, particularly into the contribution of genetic and environmental factors that interact with MeHg to modify toxicity. This review will outline cellular processes directly and indirectly affected by MeHg, including oxidative stress, cellular signaling and gene expression, and discuss genetic, environmental and nutritional factors capable of modifying MeHg toxicity.
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Affiliation(s)
- Stephanie Jb Fretham
- Department of Pediatrics and Department of Pharmacology, and the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Samuel Caito
- Department of Pediatrics and Department of Pharmacology, and the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Ebany J Martinez-Finley
- Department of Pediatrics and Department of Pharmacology, and the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Michael Aschner
- Department of Pediatrics and Department of Pharmacology, and the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, TN, USA
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103
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Colle D, Hartwig JM, Antunes Soares FA, Farina M. Probucol modulates oxidative stress and excitotoxicity in Huntington's disease models in vitro. Brain Res Bull 2012; 87:397-405. [DOI: 10.1016/j.brainresbull.2012.01.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Revised: 12/27/2011] [Accepted: 01/01/2012] [Indexed: 10/14/2022]
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104
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Probucol, a lipid-lowering drug, prevents cognitive and hippocampal synaptic impairments induced by amyloid β peptide in mice. Exp Neurol 2011; 233:767-75. [PMID: 22173317 DOI: 10.1016/j.expneurol.2011.11.036] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 11/17/2011] [Accepted: 11/25/2011] [Indexed: 11/20/2022]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by synaptic loss and cognitive impairments. The presence of extracellular senile plaques (mainly composed of amyloid-β (Aβ) peptide) is an important molecular hallmark in AD and neuronal damage has been attributed, at least in part, to Aβ-mediated toxicity. Although the molecular mechanisms involved in the pathogenesis of AD are not yet completely understood, several lines of evidence indicate that oxidative stress and cholesterol dyshomeostasis play crucial roles in mediating the synaptic loss and cognitive deficits observed in AD patients. This study evaluated the effects of Probucol, a phenolic lipid-lowering agent with anti-inflammatory and antioxidant properties, on biochemical parameters related to oxidative stress and synaptic function (hippocampal glutathione and synaptophysin levels; glutathione peroxidase, glutathione reductase and acetylcholinesterase activities; lipid peroxidation), as well as on behavioral parameters related to the cognitive function (displaced and new object recognition tasks) in Aβ-exposed mice. Animals were treated with a single intracerebroventricular (i.c.v.) injection of aggregated Aβ(1-40) (400 pmol/site) and, subsequently, received Probucol (10 mg/kg, i.p.) once a day, during the following 2 weeks. At the end of treatments, Aβ(1-40)-exposed animals showed a significant impairment on learning-memory ability, which was paralleled by a significant decrease in hippocampal synaptophysin levels, as well as by an increase in hippocampal acetylcholinesterase activity. Importantly, Probucol treatment blunted the deleterious effects of Aβ(1-40) on learning-memory ability and hippocampal biochemistry. Although Aβ(1-40) treatment did not change hippocampal glutathione levels and glutathione peroxidase (GPx) and glutathione reductase (GR) activities, Aβ(1-40)-exposed animals showed increased hippocampal lipid peroxidation and this event was completely blunted by Probucol treatment. These findings reinforce and extend the notion of the hazardous effects of Aβ(1-40) toward hippocampal synaptic homeostasis and cognitive functions. In addition, the present results indicate that Probucol is able to counteract the cognitive and biochemical impairments induced by i.c.v. Aβ(1-40) administration in mice. The study is the first to report the protective effects of Probucol (a "non-statin cholesterol-lowering drug") against Aβ(1-40)-induced synaptic and behavioral impairments, rendering this compound a promising molecule for further pharmacological studies on the search for therapeutic strategies to treat or prevent AD.
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105
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Farina M, Aschner M, Rocha JBT. Oxidative stress in MeHg-induced neurotoxicity. Toxicol Appl Pharmacol 2011; 256:405-17. [PMID: 21601588 PMCID: PMC3166649 DOI: 10.1016/j.taap.2011.05.001] [Citation(s) in RCA: 261] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 05/01/2011] [Accepted: 05/02/2011] [Indexed: 12/20/2022]
Abstract
Methylmercury (MeHg) is an environmental toxicant that leads to long-lasting neurological and developmental deficits in animals and humans. Although the molecular mechanisms mediating MeHg-induced neurotoxicity are not completely understood, several lines of evidence indicate that oxidative stress represents a critical event related to the neurotoxic effects elicited by this toxicant. The objective of this review is to summarize and discuss data from experimental and epidemiological studies that have been important in clarifying the molecular events which mediate MeHg-induced oxidative damage and, consequently, toxicity. Although unanswered questions remain, the electrophilic properties of MeHg and its ability to oxidize thiols have been reported to play decisive roles to the oxidative consequences observed after MeHg exposure. However, a close examination of the relationship between low levels of MeHg necessary to induce oxidative stress and the high amounts of sulfhydryl-containing antioxidants in mammalian cells (e.g., glutathione) have led to the hypothesis that nucleophilic groups with extremely high affinities for MeHg (e.g., selenols) might represent primary targets in MeHg-induced oxidative stress. Indeed, the inhibition of antioxidant selenoproteins during MeHg poisoning in experimental animals has corroborated this hypothesis. The levels of different reactive species (superoxide anion, hydrogen peroxide and nitric oxide) have been reported to be increased in MeHg-exposed systems, and the mechanisms concerning these increments seem to involve a complex sequence of cascading molecular events, such as mitochondrial dysfunction, excitotoxicity, intracellular calcium dyshomeostasis and decreased antioxidant capacity. This review also discusses potential therapeutic strategies to counteract MeHg-induced toxicity and oxidative stress, emphasizing the use of organic selenocompounds, which generally present higher affinity for MeHg when compared to the classically studied agents.
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Affiliation(s)
- Marcelo Farina
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Michael Aschner
- Department of Pediatrics and Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - João B. T. Rocha
- Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
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106
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Farina M, Rocha JBT, Aschner M. Mechanisms of methylmercury-induced neurotoxicity: evidence from experimental studies. Life Sci 2011; 89:555-63. [PMID: 21683713 PMCID: PMC3183295 DOI: 10.1016/j.lfs.2011.05.019] [Citation(s) in RCA: 314] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 04/22/2011] [Accepted: 05/13/2011] [Indexed: 02/08/2023]
Abstract
Neurological disorders are common, costly, and can cause enduring disability. Although mostly unknown, a few environmental toxicants are recognized causes of neurological disorders and subclinical brain dysfunction. One of the best known neurotoxins is methylmercury (MeHg), a ubiquitous environmental toxicant that leads to long-lasting neurological and developmental deficits in animals and humans. In the aquatic environment, MeHg is accumulated in fish, which represent a major source of human exposure. Although several episodes of MeHg poisoning have contributed to the understanding of the clinical symptoms and histological changes elicited by this neurotoxicant in humans, experimental studies have been pivotal in elucidating the molecular mechanisms that mediate MeHg-induced neurotoxicity. The objective of this mini-review is to summarize data from experimental studies on molecular mechanisms of MeHg-induced neurotoxicity. While the full picture has yet to be unmasked, in vitro approaches based on cultured cells, isolated mitochondria and tissue slices, as well as in vivo studies based mainly on the use of rodents, point to impairment in intracellular calcium homeostasis, alteration of glutamate homeostasis and oxidative stress as important events in MeHg-induced neurotoxicity. The potential relationship among these events is discussed, with particular emphasis on the neurotoxic cycle triggered by MeHg-induced excitotoxicity and oxidative stress. The particular sensitivity of the developing brain to MeHg toxicity, the critical role of selenoproteins and the potential protective role of selenocompounds are also discussed. These concepts provide the biochemical bases to the understanding of MeHg neurotoxicity, contributing to the discovery of endogenous and exogenous molecules that counteract such toxicity and provide efficacious means for ablating this vicious cycle.
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Affiliation(s)
- Marcelo Farina
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
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107
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Lubos E, Loscalzo J, Handy DE. Glutathione peroxidase-1 in health and disease: from molecular mechanisms to therapeutic opportunities. Antioxid Redox Signal 2011; 15:1957-97. [PMID: 21087145 PMCID: PMC3159114 DOI: 10.1089/ars.2010.3586] [Citation(s) in RCA: 830] [Impact Index Per Article: 59.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Reactive oxygen species, such as superoxide and hydrogen peroxide, are generated in all cells by mitochondrial and enzymatic sources. Left unchecked, these reactive species can cause oxidative damage to DNA, proteins, and membrane lipids. Glutathione peroxidase-1 (GPx-1) is an intracellular antioxidant enzyme that enzymatically reduces hydrogen peroxide to water to limit its harmful effects. Certain reactive oxygen species, such as hydrogen peroxide, are also essential for growth factor-mediated signal transduction, mitochondrial function, and maintenance of normal thiol redox-balance. Thus, by limiting hydrogen peroxide accumulation, GPx-1 also modulates these processes. This review explores the molecular mechanisms involved in regulating the expression and function of GPx-1, with an emphasis on the role of GPx-1 in modulating cellular oxidant stress and redox-mediated responses. As a selenocysteine-containing enzyme, GPx-1 expression is subject to unique forms of regulation involving the trace mineral selenium and selenocysteine incorporation during translation. In addition, GPx-1 has been implicated in the development and prevention of many common and complex diseases, including cancer and cardiovascular disease. This review discusses the role of GPx-1 in these diseases and speculates on potential future therapies to harness the beneficial effects of this ubiquitous antioxidant enzyme.
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Affiliation(s)
- Edith Lubos
- Department of Medicine II, University Medical Center, Johannes Gutenberg-University, Mainz, Germany
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108
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Hernández RB, Farina M, Espósito BP, Souza-Pinto NC, Barbosa F, Suñol C. Mechanisms of Manganese-Induced Neurotoxicity in Primary Neuronal Cultures: The Role of Manganese Speciation and Cell Type. Toxicol Sci 2011; 124:414-23. [DOI: 10.1093/toxsci/kfr234] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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109
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Falk MJ, Polyak E, Zhang Z, Peng M, King R, Maltzman JS, Okwuego E, Horyn O, Nakamaru-Ogiso E, Ostrovsky J, Xie LX, Chen JY, Marbois B, Nissim I, Clarke CF, Gasser DL. Probucol ameliorates renal and metabolic sequelae of primary CoQ deficiency in Pdss2 mutant mice. EMBO Mol Med 2011; 3:410-27. [PMID: 21567994 PMCID: PMC3394513 DOI: 10.1002/emmm.201100149] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 04/27/2011] [Accepted: 04/28/2011] [Indexed: 11/16/2022] Open
Abstract
Therapy of mitochondrial respiratory chain diseases is complicated by limited understanding of cellular mechanisms that cause the widely variable clinical findings. Here, we show that focal segmental glomerulopathy-like kidney disease in Pdss2 mutant animals with primary coenzyme Q (CoQ) deficiency is significantly ameliorated by oral treatment with probucol (1% w/w). Preventative effects in missense mutant mice are similar whether fed probucol from weaning or for 3 weeks prior to typical nephritis onset. Furthermore, treating symptomatic animals for 2 weeks with probucol significantly reduces albuminuria. Probucol has a more pronounced health benefit than high-dose CoQ10 supplementation and uniquely restores CoQ9 content in mutant kidney. Probucol substantially mitigates transcriptional alterations across many intermediary metabolic domains, including peroxisome proliferator-activated receptor (PPAR) pathway signaling. Probucol's beneficial effects on the renal and metabolic manifestations of Pdss2 disease occur despite modest induction of oxidant stress and appear independent of its hypolipidemic effects. Rather, decreased CoQ9 content and altered PPAR pathway signaling appear, respectively, to orchestrate the glomerular and global metabolic consequences of primary CoQ deficiency, which are both preventable and treatable with oral probucol therapy.
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Affiliation(s)
- Marni J Falk
- Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.
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110
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Yin Z, Lee E, Ni M, Jiang H, Milatovic D, Rongzhu L, Farina M, Rocha JBT, Aschner M. Methylmercury-induced alterations in astrocyte functions are attenuated by ebselen. Neurotoxicology 2011; 32:291-9. [PMID: 21300091 PMCID: PMC3079013 DOI: 10.1016/j.neuro.2011.01.004] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 12/21/2010] [Accepted: 01/08/2011] [Indexed: 12/26/2022]
Abstract
Methylmercury (MeHg) preferentially accumulates in glia of the central nervous system (CNS), but its toxic mechanisms have yet to be fully recognized. In the present study, we tested the hypothesis that MeHg induces neurotoxicity via oxidative stress mechanisms, and that these effects are attenuated by the antioxidant, ebselen. Rat neonatal primary cortical astrocytes were pretreated with or without 10 μM ebselen for 2h followed by MeHg (0, 1, 5, and 10 μM) treatments. MeHg-induced changes in astrocytic [(3)H]-glutamine uptake were assessed along with changes in mitochondrial membrane potential (ΔΨ(m)), using the potentiometric dye tetramethylrhodamine ethyl ester (TMRE). Western blot analysis was used to detect MeHg-induced ERK (extracellular-signal related kinase) phosphorylation and caspase-3 activation. MeHg treatment significantly decreased (p<0.05) astrocytic [(3)H]-glutamine uptake at all time points and concentrations. Ebselen fully reversed MeHg's (1 μM) effect on [(3)H]-glutamine uptake at 1 min. At higher MeHg concentrations, ebselen partially reversed the MeHg-induced astrocytic inhibition of [(3)H]-glutamine uptake [at 1 min (5 and 10 μM) (p<0.05); 5 min (1, 5 and 10 μM) (p<0.05)]. MeHg treatment (1h) significantly (p<0.05) dissipated the ΔΨ(m) in astrocytes as evidenced by a decrease in mitochondrial TMRE fluorescence. Ebselen fully reversed the effect of 1 μM MeHg treatment for 1h on astrocytic ΔΨ(m) and partially reversed the effect of 5 and 10 μM MeHg treatments for 1h on ΔΨ(m). In addition, ebselen inhibited MeHg-induced phosphorylation of ERK (p<0.05) and blocked MeHg-induced activation of caspase-3 (p<0.05-0.01). These results are consistent with the hypothesis that MeHg exerts its toxic effects via oxidative stress and that the phosphorylation of ERK and the dissipation of the astrocytic mitochondrial membrane potential are involved in MeHg toxicity. In addition, the protective effects elicited by ebselen reinforce the idea that organic selenocompounds represent promising strategies to counteract MeHg-induced neurotoxicity.
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MESH Headings
- Analysis of Variance
- Animals
- Animals, Newborn
- Antioxidants/pharmacology
- Astrocytes/drug effects
- Astrocytes/metabolism
- Astrocytes/pathology
- Azoles/pharmacology
- Blotting, Western
- Caspase 3/metabolism
- Cells, Cultured
- Cytoprotection
- Dose-Response Relationship, Drug
- Environmental Pollutants/toxicity
- Extracellular Signal-Regulated MAP Kinases/metabolism
- Glutamine/metabolism
- Isoindoles
- Membrane Potential, Mitochondrial/drug effects
- Mercury Poisoning, Nervous System/etiology
- Mercury Poisoning, Nervous System/metabolism
- Mercury Poisoning, Nervous System/pathology
- Methylmercury Compounds/toxicity
- Microscopy, Fluorescence
- Mitochondria/drug effects
- Mitochondria/metabolism
- Neuroprotective Agents/pharmacology
- Organoselenium Compounds/pharmacology
- Oxidative Stress/drug effects
- Phosphorylation
- Rats
- Rats, Sprague-Dawley
- Time Factors
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Affiliation(s)
- Zhaobao Yin
- Departments of Pediatrics and Pharmacology, the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Eunsook Lee
- Department of Physiology, Meharry Medical College, Nashville, Tennessee
| | - Mingwei Ni
- Departments of Pediatrics and Pharmacology, the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Haiyan Jiang
- Departments of Pediatrics and Pharmacology, the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Dejan Milatovic
- Departments of Pediatrics and Pharmacology, the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Lu Rongzhu
- Departments of Pediatrics and Pharmacology, the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Marcelo Farina
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Joao B. T. Rocha
- Departamento de Bioquímica, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Michael Aschner
- Departments of Pediatrics and Pharmacology, the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, Tennessee
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111
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Ni M, Li X, Yin Z, Sidoryk-Węgrzynowicz M, Jiang H, Farina M, Rocha JBT, Syversen T, Aschner M. Comparative study on the response of rat primary astrocytes and microglia to methylmercury toxicity. Glia 2011; 59:810-20. [PMID: 21351162 PMCID: PMC3080116 DOI: 10.1002/glia.21153] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Accepted: 01/11/2011] [Indexed: 12/16/2022]
Abstract
As the two major glial cell types in the brain, astrocytes and microglia play pivotal but different roles in maintaining optimal brain function. Although both cell types have been implicated as major targets of methylmercury (MeHg), their sensitivities and adaptive responses to this metal can vary given their distinctive properties and physiological functions. This study was carried out to compare the responses of astrocytes and microglia following MeHg treatment, specifically addressing the effects of MeHg on cell viability, reactive oxygen species (ROS) generation and glutathione (GSH) levels, as well as mercury (Hg) uptake and the expression of NF-E2-related factor 2 (Nrf2). Results showed that microglia are more sensitive to MeHg than astrocytes, a finding that is consistent with their higher Hg uptake and lower basal GSH levels. Microglia also demonstrated higher ROS generation compared with astrocytes. Nrf2 and its downstream genes were upregulated in both cell types, but with different kinetics (much faster in microglia). In summary, microglia and astrocytes each exhibit a distinct sensitivity to MeHg, resulting in their differential temporal adaptive responses. These unique sensitivities appear to be dependent on the cellular thiol status of the particular cell type.
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Affiliation(s)
- Mingwei Ni
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Xin Li
- Neuroscience Graduate Program, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Zhaobao Yin
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232
| | | | - Haiyan Jiang
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Marcelo Farina
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Joao B. T. Rocha
- Departamento de Bioquímica, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Tore Syversen
- Department of Neuroscience, Norwegian University of Science and Technology, Faculty of Medicine, Trondheim, Norway
| | - Michael Aschner
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232
- Neuroscience Graduate Program, Vanderbilt University Medical Center, Nashville, TN 37232
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232
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112
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Farina M, Berenguer J, Pons S, da Rocha JBT, Aschner M. Introducing cloned genes into cultured neurons providing novel in vitro models for neuropathology and neurotoxicity studies. NEUROMETHODS 2011; 56:185-222. [PMID: 32132768 PMCID: PMC7055714 DOI: 10.1007/978-1-61779-077-5_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Affiliation(s)
- Marcelo Farina
- Departamento de Bioquímica, CCB, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Jordi Berenguer
- Department of Cell Death and Proliferation, IIBB, CSIC-IDIBAPS, Barcelona, Spain
| | - Sebastián Pons
- Department of Cell Death and Proliferation, IIBB, CSIC-IDIBAPS, Barcelona, Spain
| | - João Batista Teixeira da Rocha
- Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria - RS, Brazil
| | - Michael Aschner
- Departments of Pediatrics and Pharmacology, and the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, TN, USA
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113
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Roos DH, Puntel RL, Farina M, Aschner M, Bohrer D, Rocha JBT, de Vargas Barbosa NB. Modulation of methylmercury uptake by methionine: prevention of mitochondrial dysfunction in rat liver slices by a mimicry mechanism. Toxicol Appl Pharmacol 2011; 252:28-35. [PMID: 21276810 DOI: 10.1016/j.taap.2011.01.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Revised: 12/21/2010] [Accepted: 01/16/2011] [Indexed: 11/28/2022]
Abstract
Methylmercury (MeHg) is an ubiquitous environmental pollutant which is transported into the mammalian cells when present as the methylmercury-cysteine conjugate (MeHg-Cys). With special emphasis on hepatic cells, due to their particular propensity to accumulate an appreciable amount of Hg after exposure to MeHg, this study was performed to evaluate the effects of methionine (Met) on Hg uptake, reactive species (RS) formation, oxygen consumption and mitochondrial function/cellular viability in both liver slices and mitochondria isolated from these slices, after exposure to MeHg or the MeHg-Cys complex. The liver slices were pre-treated with Met (250 μM) 15 min before being exposed to MeHg (25 μM) or MeHg-Cys (25 μM each) for 30 min at 37 °C. The treatment with MeHg caused a significant increase in the Hg concentration in both liver slices and mitochondria isolated from liver slices. Moreover, the Hg uptake was higher in the group exposed to the MeHg-Cys complex. In the DCF (dichlorofluorescein) assay, the exposure to MeHg and MeHg-Cys produced a significant increase in DFC reactive species (DFC-RS) formation only in the mitochondria isolated from liver slices. As observed with Hg uptake, DFC-RS levels were significantly higher in the mitochondria treated with the MeHg-Cys complex compared to MeHg alone. MeHg exposure also caused a marked decrease in the oxygen consumption of liver slices when compared to the control group, and this effect was more pronounced in the liver slices treated with the MeHg-Cys complex. Similarly, the loss of mitochondrial activity/cell viability was greater in liver slices exposed to the MeHg-Cys complex when compared to slices treated only with MeHg. In all studied parameters, Met pre-treatment was effective in preventing the MeHg- and/or MeHg-Cys-induced toxicity in both liver slices and mitochondria. Part of the protection afforded by Met against MeHg may be related to a direct interaction with MeHg or to the competition of Met with the complex formed between MeHg and endogenous cysteine. In summary, our results show that Met pre-treatment produces pronounced protection against the toxic effects induced by MeHg and/or the MeHg-Cys complex on mitochondrial function and cell viability. Consequently, this amino acid offers considerable promise as a potential agent for treating acute MeHg exposure.
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Affiliation(s)
- Daniel Henrique Roos
- Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, CEP 97105-900, Brazil
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114
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Franco JL, Posser T, Missau F, Pizzolatti MG, dos Santos ARS, Souza DO, Aschner M, Rocha JBT, Dafre AL, Farina M. Structure-activity relationship of flavonoids derived from medicinal plants in preventing methylmercury-induced mitochondrial dysfunction. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2010; 30:272-278. [PMID: 21127717 PMCID: PMC2992974 DOI: 10.1016/j.etap.2010.07.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
In the present study, we investigated the potential protective effects of three flavonoids (myricetin, myricitrin and rutin) derived from medicinal plants against methyl mercury (MeHg)-induced mitochondrial dysfunction in vitro. Incubation of mouse brain mitochondria with MeHg induced a significant decrease in mitochondrial function, which was correlated with decreased glutathione (GSH) levels and increased generation of reactive oxygen species (ROS) and lipid peroxidation. The co-incubation of mouse brain mitochondria with myricetin or myricitrin caused a concentration-dependent decrease of MeHg-induced mitochondrial dysfunction and oxidative stress. The flavonoid rutin was ineffective in counteracting MeHg toxicity. Among the three tested flavonoids, myricetin was the most efficient in protecting against MeHg-induced mitochondrial dysfunction. Moreover, myricetin completely blocked MeHg-induced ROS formation and lipid peroxidation and partially prevented MeHg-induced GSH depletion. The ability of myricetin to attenuate MeHg-induced mitochondrial dysfunction and oxidative stress appears to be related to its higher scavenging capability when compared to myricitrin and rutin. Overall, the results suggest that MeHg-induced mitotoxicity is associated with oxidative stress. The ability of myricetin to prevent MeHg-induced oxidative damage in brain mitochondria renders this flavonoid a promising molecule for further in vivo studies in the search for potential antidotes to counteract MeHg-induced neurotoxicity.
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Affiliation(s)
- Jeferson L. Franco
- Departamento de Bioquímica Centro de Ciências Biológicas Universidade Federal de Santa Catarina, Florianópolis - SC, Brazil
- Campus São Gabriel, Universidade Federal do Pampa, São Gabriel - RS, Brazil
| | - Thais Posser
- Departamento de Bioquímica Centro de Ciências Biológicas Universidade Federal de Santa Catarina, Florianópolis - SC, Brazil
- Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria - RS, Brazil
| | - Fabiana Missau
- Departamento de Química, Centro de Ciências Físicas e Matemáticas, Universidade Federal de Santa Catarina, Florianópolis - SC, Brazil
| | - Moacir G. Pizzolatti
- Departamento de Química, Centro de Ciências Físicas e Matemáticas, Universidade Federal de Santa Catarina, Florianópolis - SC, Brazil
| | - Adair R. S. dos Santos
- Departamento de Ciências Fisiológicas, Centro de Ciências Biológicas Universidade Federal de Santa Catarina, Florianópolis - SC, Brazil
| | - Diogo O. Souza
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre - RS, Brazil
| | - Michael Aschner
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - João B. T. Rocha
- Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria - RS, Brazil
| | - Alcir L. Dafre
- Departamento de Bioquímica Centro de Ciências Biológicas Universidade Federal de Santa Catarina, Florianópolis - SC, Brazil
| | - Marcelo Farina
- Departamento de Bioquímica Centro de Ciências Biológicas Universidade Federal de Santa Catarina, Florianópolis - SC, Brazil
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Wagner C, Sudati JH, Nogueira CW, Rocha JBT. In vivo and in vitro inhibition of mice thioredoxin reductase by methylmercury. Biometals 2010; 23:1171-7. [DOI: 10.1007/s10534-010-9367-4] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Accepted: 07/15/2010] [Indexed: 10/19/2022]
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Posser T, Dunkley PR, Dickson PW, Franco JL. Human neuroblastoma cells transfected with tyrosine hydroxylase gain increased resistance to methylmercury-induced cell death. Toxicol In Vitro 2010; 24:1498-503. [PMID: 20650311 DOI: 10.1016/j.tiv.2010.07.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 07/12/2010] [Accepted: 07/15/2010] [Indexed: 11/26/2022]
Abstract
In a previous study we demonstrated that human neuroblastoma SH-SY5Y cells transfected with human tyrosine hydroxylase isoform 1 (SH+TH cells) were substantially more resistant to cell death induced by pro-oxidants than wild type SH-SY5Y cells (SH cells). In the present communication we used methylmercury as a model of cell stress in order to test whether SH+TH cells would behave in a similar manner in response to this stressor. Incubation with methylmercury (0.1-3 microM) for 24h caused a significant reduction in cell viability and increased apoptotic markers in both cell types. However, the effects were significantly reduced in the SH+TH cells when compared to the SH cells. Activation of p38(MAPK) was also reduced in the SH+TH compared to the SH cells after methylmercury exposure. Since p38(MAPK) is known to participate in signal transduction pathways during cell stress, our data suggest that SH+TH cells develop an increased resistance to environmental stress caused by neurotoxins such as methylmercury. In conclusion our results show that insertion of the human TH gene in cells that originally do not express this protein leads to alterations in cell homeostasis and triggers defense mechanisms against pro-oxidative insults.
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Affiliation(s)
- Thaís Posser
- Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, Brazil
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