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Nakamura M, Tatsuta N, Murata K, Nakai K, Iwata T, Otobe T, Sakamoto M, Yamamoto M, Itatani M, Miura Y, Koriyama C. Neurodevelopmental associations of prenatal and postnatal methylmercury exposure among first-grade children in the Kinan region, Japan. ENVIRONMENTAL RESEARCH 2023; 235:116688. [PMID: 37467938 DOI: 10.1016/j.envres.2023.116688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 07/14/2023] [Accepted: 07/15/2023] [Indexed: 07/21/2023]
Abstract
The most severe effects of methylmercury (MeHg) exposure during child development are thought to result from exposure during fetal life and childhood. However, comparing the neurodevelopmental effects of prenatal and postnatal MeHg exposure (PreMeHg and PostMeHg, respectively) remains unclear. We aimed to investigate the associations between neurodevelopmental indicators and PreMeHg or PostMeHg. The participants were 134 children in the first grade of elementary schools aged 7-8 years from the Kinan region, an area with high consumption of MeHg-rich whales and tunas in Japan. We measured MeHg levels in preserved umbilical cord tissues and total mercury (T-Hg) levels in children's hair to estimate PreMeHg and PostMeHg levels, respectively. Neuropsychological (intelligence quotient testing and Boston Naming Test) and neurophysiological (brainstem auditory evoked potential [BAEP], visual evoked potential [VEP], and color vision tests) studies were performed to evaluate the neurodevelopmental status. Multiple regression analyses were conducted according to sex. The geometric mean MeHg levels in preserved umbilical cord tissues and T-Hg levels in children's hair were 0.11 μg/g and 2.94 μg/g, respectively. Neither PreMeHg nor PostMeHg was related to neuropsychological indicators. Some associations between MeHg exposure and neurophysiological results were observed only in boys. N145 latency in VEPs was significantly prolonged with increasing PreMeHg (β: 12.01, 95% confidence interval [CI]: 0.648, 23.38). The III-V interpeak intervals in BAEP were significantly prolonged with increasing PreMeHg or PostMeHg (β [95% CI]: 0.142 [0.041, 0.243] and 0.159 [0.052, 0.265], respectively). After adjusting for PreMeHg, the association between PostMeHg and BAEP latencies disappeared. In conclusion, the latency in the auditory and visual pathways was significantly prolonged with increasing PreMeHg in boys. These findings suggest that male fetuses may be more susceptible to MeHg exposure.
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Affiliation(s)
- Masaaki Nakamura
- Department of Clinical Medicine, National Institute for Minamata Disease, 4058-18 Hama, Minamata City, Kumamoto, 867-0008, Japan.
| | - Nozomi Tatsuta
- Development and Environmental Medicine, Tohoku University Graduate School of Medicine, Sendai City, Miyagi, 980-8575, Japan.
| | - Katsuyuki Murata
- Department of Environmental Health Sciences, Akita University Graduate School of Medicine, 1-1 Hondo, Akita City, Akita, 010-8543, Japan.
| | - Kunihiko Nakai
- Development and Environmental Medicine, Tohoku University Graduate School of Medicine, Sendai City, Miyagi, 980-8575, Japan.
| | - Toyoto Iwata
- Department of Environmental Health Sciences, Akita University Graduate School of Medicine, 1-1 Hondo, Akita City, Akita, 010-8543, Japan.
| | - Takayuki Otobe
- Department of Child Education, Jin-ai University, Echizen City, Fukui, 910-0124, Japan.
| | - Mineshi Sakamoto
- Department of Environment and Public Health, National Institute for Minamata Disease, 4058-18 Hama, Minamata City, Kumamoto, 867-0008, Japan.
| | - Megumi Yamamoto
- Department of Environment and Public Health, National Institute for Minamata Disease, 4058-18 Hama, Minamata City, Kumamoto, 867-0008, Japan.
| | - Mina Itatani
- Department of Clinical Medicine, National Institute for Minamata Disease, 4058-18 Hama, Minamata City, Kumamoto, 867-0008, Japan.
| | - Yoko Miura
- Department of Clinical Medicine, National Institute for Minamata Disease, 4058-18 Hama, Minamata City, Kumamoto, 867-0008, Japan.
| | - Chihaya Koriyama
- Department of Epidemiology and Preventive Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima, 890-8544, Japan.
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Bjørklund G, Antonyak H, Polishchuk A, Semenova Y, Lesiv M, Lysiuk R, Peana M. Effect of methylmercury on fetal neurobehavioral development: an overview of the possible mechanisms of toxicity and the neuroprotective effect of phytochemicals. Arch Toxicol 2022; 96:3175-3199. [PMID: 36063174 DOI: 10.1007/s00204-022-03366-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 08/17/2022] [Indexed: 11/25/2022]
Abstract
Methylmercury (MeHg) is a global environmental pollutant with neurotoxic effects. Exposure to MeHg via consumption of seafood and fish can severely impact fetal neurobehavioral development even when MeHg levels in maternal blood are as low as about 5 μg/L, which the mother tolerates well. Persistent motor dysfunctions and cognitive deficits may result from trans-placental exposure. The present review summarizes current knowledge on the mechanisms of MeHg toxicity during the period of nervous system development. Although cerebellar Purkinje cells are MeHg targets, the actions of MeHg on thiol components in the neuronal cytoskeleton as well as on mitochondrial enzymes and induction of disturbances of glutamate signaling can impair extra-cerebellar functions, also at levels well tolerated by adult individuals. Numerous herbal substances possess neuroprotective effects, predominantly represented by natural polyphenolic molecules that might be utilized to develop natural drugs to alleviate neurotoxicity symptoms caused by MeHg or other Hg compounds.
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Affiliation(s)
- Geir Bjørklund
- Council for Nutritional and Environmental Medicine, Toften 24, 8610, Mo i Rana, Norway.
| | | | | | | | - Marta Lesiv
- Ivan Franko National University of Lviv, Lviv, Ukraine
| | - Roman Lysiuk
- Danylo Halytsky Lviv National Medical University, Lviv, Ukraine
- CONEM Ukraine Life Science Research Group, Danylo Halytsky Lviv National Medical University, Lviv, Ukraine
| | - Massimiliano Peana
- Department of Chemical, Physics, Mathematics and Natural Sciences, University of Sassari, Sassari, Italy
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Fujimura M, Usuki F. Cellular Conditions Responsible for Methylmercury-Mediated Neurotoxicity. Int J Mol Sci 2022; 23:ijms23137218. [PMID: 35806222 PMCID: PMC9266708 DOI: 10.3390/ijms23137218] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 06/25/2022] [Accepted: 06/27/2022] [Indexed: 12/10/2022] Open
Abstract
Methylmercury (MeHg) is a widely known environmental pollutant that causes severe neurotoxicity. MeHg-induced neurotoxicity depends on various cellular conditions, including differences in the characteristics of tissues and cells, exposure age (fetal, childhood, or adulthood), and exposure levels. Research has highlighted the importance of oxidative stress in the pathogenesis of MeHg-induced toxicity and the site- and cell-specific nature of MeHg-induced neurotoxicity. The cerebellar granule cells and deeper layer cerebrocortical neurons are vulnerable to MeHg. In contrast, the hippocampal neurons are resistant to MeHg, even at high mercury accumulation levels. This review summarizes the mechanisms underlying MeHg-mediated intracellular events that lead to site-specific neurotoxicity. Specifically, we discuss the mechanisms associated with the redox ability, neural outgrowth and synapse formation, cellular signaling pathways, epigenetics, and the inflammatory conditions of microglia.
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Affiliation(s)
- Masatake Fujimura
- Department of Basic Medical Sciences, National Institute for Minamata Disease, Kumamoto 867-0008, Japan
- Correspondence: ; Tel.: +81-966-63-3111; Fax: +81-966-61-1145
| | - Fusako Usuki
- Division of Neuroimmunology, Joint Research Center for Human Retrovirus Infection, Kagoshima University, Kagoshima 890-8544, Japan;
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Nogueira LS, Vasconcelos CP, Mitre GP, Kataoka MSDS, Bittencourt LO, Lima MO, de Oliveira EHC, Crespo-Lopez ME, Lima RR. Metabolic and oxidative impairments in human salivary gland cells line exposed to MeHg. J Trace Elem Med Biol 2021; 66:126747. [PMID: 33773279 DOI: 10.1016/j.jtemb.2021.126747] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 01/17/2021] [Accepted: 03/15/2021] [Indexed: 12/20/2022]
Abstract
BACKGROUND/AIM The ingestion of contaminated seafood by MeHg is considered the main route of human exposure, turning the salivary gland one important target organ. The salivary glands play critical roles in maintaining oral health homeostasis, producing saliva that maintains the oral microbiota, initiation of the digestion of macromolecules, and being essential in maintaining the integrity of the adjacent soft tissues and teeth. Thus, this study aimed to investigate the effects of MeHg exposure on human salivary gland cells line. METHODS Cells were exposed to 1-6 μM of MeHg for 24 h, and analysis of toxicity was performed. Based on these results, the LC50 was calculated and two concentrations were chosen (0.25 and 2.5 μM MeHg) to evaluate intracellular mercury (Hg) accumulation (THg), metabolic viability and oxidative stress parameters (GSH:GSSG ratio, lipid peroxidation, protein oxidation and DNA damage). RESULTS The results demonstrated accumulation of THg as we increased the MeHg concentrations in the exposure and, the higher the dose, the lower is the cell metabolic response. In addition, the 2.5 μM MeHg concentration also triggered oxidative stress in human salivary gland cells by depleting the antioxidant competence of GSH:GSSG ratio and increasing lipid peroxidation and proteins carbonyl levels, but no damages to DNA integrity. CONCLUSION In conclusion, although these two elected doses did not show lethal effects, the highest dose triggered oxidative stress and new questionings about long-term exposure models are raised to investigate furthers cellular damages to human salivary gland cells caused by MeHg exposure to extrapolate in a translational perspective.
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Affiliation(s)
- Lygia S Nogueira
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, PA, Brazil
| | - Carolina P Vasconcelos
- Laboratory of Cell Culture and Cytogenetics, Environment Section, Evandro Chagas Institute, Ananindeua, PA, Brazil
| | | | | | - Leonardo Oliveira Bittencourt
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, PA, Brazil
| | - Marcelo O Lima
- Laboratory of Toxicology, Environment Section, Evandro Chagas Institute, Ananindeua, PA, Brazil
| | - Edivaldo H C de Oliveira
- Laboratory of Cell Culture and Cytogenetics, Environment Section, Evandro Chagas Institute, Ananindeua, PA, Brazil
| | - Maria Elena Crespo-Lopez
- Laboratory of Molecular Pharmacology, Institute of Biological Sciences, Federal University of Pará, Belém, PA, Brazil
| | - Rafael Rodrigues Lima
- Laboratory of Functional and Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém, PA, Brazil.
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Fujimura M, Usuki F. Methylmercury-Mediated Oxidative Stress and Activation of the Cellular Protective System. Antioxidants (Basel) 2020; 9:antiox9101004. [PMID: 33081221 PMCID: PMC7602710 DOI: 10.3390/antiox9101004] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/09/2020] [Accepted: 10/14/2020] [Indexed: 12/17/2022] Open
Abstract
Methylmercury (MeHg) is a well-known neurotoxicant that causes severe intoxication in humans. In Japan, it is referred to as Minamata disease, which involves two characteristic clinical forms: fetal type and adult type depending on the exposed age. In addition to MeHg burden level, individual susceptibility to MeHg plays a role in the manifestation of MeHg toxicity. Research progress has pointed out the importance of oxidative stress in the pathogenesis of MeHg toxicity. MeHg has a high affinity for selenohydryl groups, sulfhydryl groups, and selenides. It has been clarified that such affinity characteristics cause the impairment of antioxidant enzymes and proteins, resulting in the disruption of antioxidant systems. Furthermore, MeHg-induced intracellular selenium deficiency due to the greater affinity of MeHg for selenohydryl groups and selenides leads to failure in the recoding of a UGA codon for selenocysteine and results in the degradation of antioxidant selenoenzyme mRNA by nonsense-mediated mRNA decay. The defect of antioxidant selenoenzyme replenishment exacerbates MeHg-mediated oxidative stress. On the other hand, it has also been revealed that MeHg can directly activate the antioxidant Keap1/Nrf2 signaling pathway. This review summarizes the incidence of MeHg-mediated oxidative stress from the viewpoint of the individual intracellular redox system interactions and the MeHg-mediated aforementioned intracellular events. In addition, the mechanisms of cellular stress pathways and neuronal cell death triggered by MeHg-mediated oxidative stress and direct interactions of MeHg with reactive residues of proteins are mentioned.
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Affiliation(s)
- Masatake Fujimura
- Department of Basic Medical Sciences, National Institute for Minamata Disease, Kumamoto 867-0008, Japan;
| | - Fusako Usuki
- Division of Neuroimmunology, Joint Research Center for Human Retrovirus Infection, Kagoshima University, Kagoshima 890-8544, Japan
- Correspondence: ; Tel.: +81-99-275-6246; Fax: +81-99-275-5942
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Fujimura M, Usuki F, Unoki T. Decreased plasma thiol antioxidant capacity precedes neurological signs in a rat methylmercury intoxication model. Food Chem Toxicol 2020; 146:111810. [PMID: 33058990 DOI: 10.1016/j.fct.2020.111810] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 10/06/2020] [Accepted: 10/07/2020] [Indexed: 12/13/2022]
Abstract
The main target organ for MeHg is the nervous system, and its neurological dysfunction remains irreversible. Therefore, predictive biomarkers associated with individual susceptibility to MeHg and future clinical severity are needed to protect against the progression of MeHg toxicity. In this study, we demonstrated that plasma thiol antioxidant capacity (-SHp) is a useful predictive biomarker associated with future clinical severity using MeHg-intoxicated rats administered 1 mg/kg/day for 4 weeks. Blood samples were collected from the subclavian vein of each rat once a week to examine total blood mercury concentrations and the levels of plasma oxidative stress markers. Time course analyses of the correlation between these weekly blood examination values and hind limb crossing signs score after 4 weeks of MeHg exposure were performed, and plasma -SHp levels after 2 weeks of MeHg exposure showed strong correlations with future hind limb crossing sign scores. Neuropathological changes also developed in parallel with hind limb crossing sign scores. Quantitative analysis of vacuolar areas in the spinal cord showed a strong correlation with hind limb crossing sign scores. In conclusion, evaluation of plasma -SHp levels allowed us to detect individuals at risk for health damage and could protect the sensitive population against MeHg toxicity.
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Affiliation(s)
- Masatake Fujimura
- Department of Basic Medical Science, National Institute for Minamata Disease, Kumamoto, Japan.
| | - Fusako Usuki
- Division of Neuroimmunology, Joint Research Center for Human Retrovirus Infection, Kagoshima University, Kagoshima, Japan
| | - Takamitsu Unoki
- Department of Basic Medical Science, National Institute for Minamata Disease, Kumamoto, Japan
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Vorojeikina D, Broberg K, Love TM, Davidson PW, van Wijngaarden E, Rand MD. Editor's Highlight: Glutathione S-Transferase Activity Moderates Methylmercury Toxicity During Development in Drosophila. Toxicol Sci 2017; 157:211-221. [PMID: 28184905 PMCID: PMC5837650 DOI: 10.1093/toxsci/kfx033] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Glutathione (GSH) pathways play a central role in methylmercury (MeHg) metabolism and elimination, largely due to formation of a more readily transported MeHg-GSH conjugate. Glutathione S-transferases (GSTs) have therefore been proposed to facilitate MeHg elimination by catalyzing MeHg-GSH conjugation. A role for human GSTP1 in MeHg disposition is suggested by the association of two common polymorphisms in the coding region (Ile105Val and Ala114Val) with Hg levels in either blood or hair. In this study, we investigated a functional role for GSTs in modulating MeHg toxicity during development. Using the Drosophila model to execute targeted manipulations of both endogenous GSTs and introduced human GSTP1 variants we correlate gene and protein expression levels with GST activity and also with MeHg body burden and developmental outcomes. RNAi knockdown of endogenous GSTD1, GSTE1, or GSTS1, individually, increased susceptibility to MeHg during pupal development resulting in a reduced rate of adult eclosion. Exogenous expression of human GSTP1 in developing flies resulted in increased MeHg tolerance relative to control flies as seen with elevated eclosion rates when reared on MeHg containing food. Furthermore, the GSTP1105 and GSTP1114 variants showed a reduced enzyme activity relative to wild-type GSTP1 (GSTP1wt). Finally, we observed a trend whereby Hg body burden was inversely related to the levels of GST activity. However, in some instances GSTP1 expression resulted in increased eclosion rates without reducing Hg body burden suggesting that GSTs interact with MeHg via both toxicokinetic and toxicodynamic mechanisms. These findings indicate that GSTs moderate MeHg toxicity during development in our experimental model.
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Affiliation(s)
| | - Karin Broberg
- The Institute of Environmental Medicine, Unit of Metals & Health, Karolinska Institute, Stockholm, Sweden
- Department of Laboratory Medicine, Division of Occupational and Environmental Medicine, Lund University, Lund, Sweden
| | - Tanzy M. Love
- Department of Pediatrics
- Department of Biostatistics and Computational Biology
| | | | - Edwin van Wijngaarden
- Department of Environmental Medicine
- Department of Pediatrics
- Department of Public Health SciencesDepartment of Dentistry, University of Rochester School of Medicine and Dentistry, Rochester, New York
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Sumathi T, Christinal J. Neuroprotective Effect of Portulaca oleraceae Ethanolic Extract Ameliorates Methylmercury Induced Cognitive Dysfunction and Oxidative Stress in Cerebellum and Cortex of Rat Brain. Biol Trace Elem Res 2016; 172:155-165. [PMID: 26563420 DOI: 10.1007/s12011-015-0546-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 10/15/2015] [Indexed: 12/30/2022]
Abstract
Methylmercury (MeHg) is highly toxic, and its principal target tissue in human is the nervous system, which has made MeHg intoxication a public health concern for many decades. Portulaca oleraceae (purslane), a member of the Portulacaceae family, is widespread as a weed and has been ranked the eighth most common plant in the world. In this study, we sought for potential beneficial effects of Portulaca oleracea ethanolic extract (POEE) against the neurotoxicity induced by MeHg in cerebellum and cortex of rats. Male Wistar rats were administered with MeHg orally at a dose of 5 mg/kg b.w. for 21 days. Experimental rats were given MeHg and also administered with POEE (4 mg/kg, orally) 1 h prior to the administration of MeHg for 21 days. After MeHg exposure, we determine the mercury concentration by atomic absorption spectroscopy (AAS); mercury content was observed high in MeHg-induced group. POEE reduced the mercury content. We also observed that the activities of catalase, superoxide dismutase, glutathione peroxidase, and the level of glutathione were reduced. The levels of glutathione reductase and thiobarbituric acid reactive substance were found to be increased. The above biochemical changes were found to be reversed with POEE. Behavioral changes like decrease tail flick response, longer immobility time, and decreased motor activity were noted down during MeHg exposure. POEE pretreatment offered protection from these behavioral changes. MeHg intoxication also caused histopathological changes in cerebellum and cortex, which was found to be normalized by treatment with POEE. The present results indicate that POEE has protective effect against MeHg-induced neurotoxicity.
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Affiliation(s)
- Thangarajan Sumathi
- Department of Medical Biochemistry, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, Tamil Nadu, 600 113, India.
| | - Johnson Christinal
- Department of Medical Biochemistry, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, Tamil Nadu, 600 113, India
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Ayyathan DM, Chandrasekaran R, Thiagarajan K. Neuroprotective effect of Tagara, an Ayurvedic drug against methyl mercury induced oxidative stress using rat brain mitochondrial fractions. Altern Ther Health Med 2015; 15:268. [PMID: 26264039 PMCID: PMC4533944 DOI: 10.1186/s12906-015-0793-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 07/22/2015] [Indexed: 11/10/2022]
Abstract
BACKGROUND Methyl mercury (MeHg), an important environmental toxicant is implicated in neurological disorders such as Hunter-Russell syndrome and Autism. Therefore, the present work is in search of new drugs that can alleviate MeHg toxicity. In this connection, Tagara, an ayurvedic drug is used for assessing its neuro protective effect against MeHg toxicity. METHODS In the present study, we assessed the phytochemical contents of Tagara by colorimetric and HPLC analyses. The neuroprotective effect of Tagara on MeHg induced neurotoxicity was measured in terms of viability by MTT assay and oxidative stress in terms of catalase activity, glutathione and thiobarbituric acid reactive substance levels. Further, the chelating effect of Tagara towards MeHg was performed to identify the molecular mechanism. Statistical analysis was done by statistical package for social sciences (SPSS) version 16.0. RESULTS The results demonstrated that Tagara contains significant amounts of phenols and flavonoids. Also, HPLC analysis of Tagara revealed the presence of essential oils such as hydroxyvalerenic and valerenic acids. Our results demonstrated that exposure of rat brain mitochondrial fractions to MeHg resulted in a dose dependent death in MTT assay and IC50 value was found to be 10 μM. However, a 250 μg dose of Tagara effectively prevented MeHg induced mitochondrial damage. The oxidative stress caused by MeHg results in elevated levels of reactive oxygen species as evidenced by elevated TBARS (Thiobarbituric acid-reactive substances) levels and diminished catalase enzyme activity and glutathione content. However, Tagara at 250 μg concentration offsets these alterations caused by MeHg. Further, Tagara also diminished GSH oxidation caused by MeHg, confirming its chelating effect, one of the molecular mechanisms that triggers protection against oxidative damage. CONCLUSION Our results revealed that MeHg induced toxicity is predominantly mediated through oxidative stress mechanism and the propensity of Tagara to abolish such reactions. Hence, we propose that Tagara with a source of potential neuroprotectants may be a useful approach to alleviate MeHg associated neurotoxicity.
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Ayyathan DM, Chandrasekaran R, Thiagarajan K. Neuroprotective effect of Brahmi, an ayurvedic drug against oxidative stress induced by methyl mercury toxicity in rat brain mitochondrial-enriched fractions. Nat Prod Res 2014; 29:1046-51. [DOI: 10.1080/14786419.2014.968153] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Christinal J, Sumathi T. Effect of Bacopa monniera extract on methylmercury-induced behavioral and histopathological changes in rats. Biol Trace Elem Res 2013; 155:56-64. [PMID: 23872736 DOI: 10.1007/s12011-013-9756-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 07/04/2013] [Indexed: 11/28/2022]
Abstract
Methylmercury (MeHg) is a well-recognized environmental contaminant with established health risk to human beings by fish and marine mammal consumption. Bacopa monniera (BM) is a perennial herb and is used as a nerve tonic in Ayurveda, a traditional medicine system in India. This study was aimed to evaluate the effect of B. monniera extract (BME) on MeHg-induced toxicity in rat cerebellum. Male Wistar rats were administered with MeHg orally at a dose of 5 mg/kg b.w. for 21 days. Experimental rats were given MeHg and also administered with BME (40 mg/kg, orally) 1 h prior to the administration of MeHg for 21 days. After treatment period, MeHg exposure significantly decreases the body weight and also caused the following behavioral changes. Decrease tail flick response, longer immobility time, significant decrease in motor activity, and spatial short-term memory. BME pretreatment reverted the behavioral changes to normal. MeHg exposure decreases the DNA and RNA content in cerebellum and also caused some pathological changes in cerebellum. Pretreatment with BME restored all the changes to near normal. These findings suggest that BME has a potent efficacy to alleviate MeHg-induced toxicity in rat cerebellum.
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Affiliation(s)
- Johnson Christinal
- Department of Medical Biochemistry, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, Tamil Nadu, India
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12
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Abd El-Aziz GS, El-Fark MMO, Saleh HAM. The prenatal toxic effect of methylmercury on the development of the appendicular skeleton of rat fetuses and the protective role of vitamin E. Anat Rec (Hoboken) 2012; 295:939-49. [PMID: 22549941 DOI: 10.1002/ar.22485] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2011] [Accepted: 03/27/2012] [Indexed: 11/12/2022]
Abstract
Methylmercury (MeHg) is an environmental contaminant that is found in many ecosystems. Many studies reported that MeHg toxicity is accompanied by increased lipid peroxidation that may lead to oxidative damage to DNA, RNA, and proteins. Vitamin E is considered as the most effective antioxidant preventing lipid peroxidation. The aim of this study was to evaluate the effects of MeHg exposure during pregnancy on the development of the appendicular skeleton in rat fetuses and whether vitamin E administration could reduce this toxicity. Positively mated adult female Sprague-Dawley rats were used and divided into the following experimental groups: control group, received only deionized water, and four MeHg treated groups received 1 mg of MeHg/kg/d, 2 mg of MeHg/kg/d, 1 mg of MeHg/kg/d plus 150 mg of vitamin E/kg/d, and 2 mg of MeHg/kg/d, plus 150 mg of vitamin E/kg/d starting from Day 0 of gestation. On Day 20 of gestation, the fetuses from the pregnant rats were extracted and the fetal growth parameters were evaluated. Skeletal evaluation of ossification of both fore- and hind-limbs, and coxal bones were undertaken. Results showed that treatment with MeHg caused adverse effects on fetal growth parameters and ossification of the bones. The coadministration of vitamin E with MeHg revealed an improvement in these parameters. These results suggest that vitamin E may ameliorate some aspects of MeHg developmental toxicity. The underlying and human health implications warrant further investigations.
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Affiliation(s)
- Gamal S Abd El-Aziz
- Department of Anatomy, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
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Protective Effect of Bacopa monniera on Methyl Mercury-Induced Oxidative Stress in Cerebellum of Rats. Cell Mol Neurobiol 2012; 32:979-87. [DOI: 10.1007/s10571-012-9813-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 02/04/2012] [Indexed: 01/21/2023]
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Jin X, Hidiroglou N, Lok E, Taylor M, Kapal K, Ross N, Sarafin K, Lau A, De Souza A, Chan HM, Mehta R. Dietary Selenium (Se) and Vitamin E (VE) Supplementation Modulated Methylmercury-Mediated Changes in Markers of Cardiovascular Diseases in Rats. Cardiovasc Toxicol 2011; 12:10-24. [DOI: 10.1007/s12012-011-9134-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kell DB. Towards a unifying, systems biology understanding of large-scale cellular death and destruction caused by poorly liganded iron: Parkinson's, Huntington's, Alzheimer's, prions, bactericides, chemical toxicology and others as examples. Arch Toxicol 2010; 84:825-89. [PMID: 20967426 PMCID: PMC2988997 DOI: 10.1007/s00204-010-0577-x] [Citation(s) in RCA: 286] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Accepted: 07/14/2010] [Indexed: 12/11/2022]
Abstract
Exposure to a variety of toxins and/or infectious agents leads to disease, degeneration and death, often characterised by circumstances in which cells or tissues do not merely die and cease to function but may be more or less entirely obliterated. It is then legitimate to ask the question as to whether, despite the many kinds of agent involved, there may be at least some unifying mechanisms of such cell death and destruction. I summarise the evidence that in a great many cases, one underlying mechanism, providing major stresses of this type, entails continuing and autocatalytic production (based on positive feedback mechanisms) of hydroxyl radicals via Fenton chemistry involving poorly liganded iron, leading to cell death via apoptosis (probably including via pathways induced by changes in the NF-κB system). While every pathway is in some sense connected to every other one, I highlight the literature evidence suggesting that the degenerative effects of many diseases and toxicological insults converge on iron dysregulation. This highlights specifically the role of iron metabolism, and the detailed speciation of iron, in chemical and other toxicology, and has significant implications for the use of iron chelating substances (probably in partnership with appropriate anti-oxidants) as nutritional or therapeutic agents in inhibiting both the progression of these mainly degenerative diseases and the sequelae of both chronic and acute toxin exposure. The complexity of biochemical networks, especially those involving autocatalytic behaviour and positive feedbacks, means that multiple interventions (e.g. of iron chelators plus antioxidants) are likely to prove most effective. A variety of systems biology approaches, that I summarise, can predict both the mechanisms involved in these cell death pathways and the optimal sites of action for nutritional or pharmacological interventions.
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Affiliation(s)
- Douglas B Kell
- School of Chemistry and the Manchester Interdisciplinary Biocentre, The University of Manchester, Manchester M1 7DN, UK.
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