RARE DISEASE
Fetal methylmercury syndrome
Fetal methylmercury syndrome
Fetal methylmercury syndrome
Synonyms: Congenital Minamata disease, Fetal methylmercury poisoning, Intrauterine methylmercury poisoning, Prenatal methylmercury poisoning
Synonyms: Congenital Minamata disease, Fetal methylmercury poisoning, Intrauterine methylmercury poisoning, Prenatal methylmercury poisoning
Synonyms: Congenital Minamata disease, Fetal methylmercury poisoning, Intrauterine methylmercury poisoning, Prenatal methylmercury poisoning
Drug discovery
0
drugs
With orphan designations
Overview
Fetal Methylmercury Syndrome is a neurodevelopmental disorder caused by in utero exposure to methylmercury, primarily through maternal consumption of contaminated seafood. It manifests as cerebral palsy-like symptoms, including ataxia, intellectual disability, motor deficits, and microcephaly, with lifelong cognitive and developmental impairments. Prenatal exposure disrupts neuronal migration and Purkinje cell development, leading to irreversible CNS damage, even in asymptomatic mothers [1][2][12].
Population
High-risk groups include pregnant individuals in regions with frequent fish consumption (e.g., subsistence fishers, coastal communities) or industrial mercury pollution (Minamata, Japan; Iraq outbreaks) [2][6][12].
Up to 5.8% incidence of severe fetal neurotoxicity was reported in highly exposed cohorts [2][10].
Burden
Causes ~14,186 disability-adjusted life years (DALYs) annually per birth cohort in industrialized nations, with 98% attributed to mild-to-moderate cognitive deficits [4][14].
Economic impacts include $32.6 million/year in lost lifetime earnings (Minnesota cohort) [14].
Subtle IQ loss (0.18–0.34 points per µg/L maternal blood mercury) elevates population-level risks for mild mental retardation [7][14].
Therapies
Prevention: Dietary advisories to limit high-mercury fish (e.g., swordfish, shark) during pregnancy; hair/blood mercury monitoring in high-exposure groups [12][13].
Supportive care: Early neurodevelopmental interventions (physical, occupational therapy) and special education programs [11][12].
Chelation: Reserved for acute, severe exposures due to risks of redistributing mercury to the fetus [10][13].
Categories: rare developmental anomalies during embryogenesis, rare disorders due to toxic effects, rare otorhinolaryngological diseases, rare surgical maxillo-facial diseases, rare teratologic disorders
Research Papers
139 drug discovery papers about Fetal methylmercury syndrome, with 1 first-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
139 drug discovery papers about Fetal methylmercury syndrome, with 1 first-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
categories:
Small molecules
small molecules
2025-07-21 | Thiamine Mitigates the Toxicity of Methylmercury in Cultured Fetal Fibroblast Cell Lines.
The challenge in addressing methylmercury (MeHg) poisoning primarily lies in devising effective therapeutic strategies. In this study, we explore the potential cytoprotective effects of thiamine pyrophosphate (TPP) as a novel agent to alleviate MeHg-induced complications. Fetal fibroblast cells were exposed to 100 µM MeHg with varying concentrations of TPP (12.5-100 mM). Treated and control cells were analyzed for determination of DNA and protein contents, whereas glutathione and lipid peroxidation levels were measured as oxidative stress markers. TPP reduced the cellular lipid peroxidation and restored the intracellular glutathione levels altered by MeHg, also increasing the cell DNA content in the 12.5 mM TPP treatment group. TPP treatment led to enhanced cell survival, underscoring TPP's capacity to alleviate MeHg toxicity by improving the antioxidant status. Further studies on additional oxidative stress markers and apoptotic pathways are necessary to fully elucidate the scope and mechanisms of TPP's cytoprotective effects against MeHg toxicity. While the data in this trial highlight the potential of TPP as a novel therapeutic agent for individuals exposed to MeHg, clinical studies are required to confirm its protective efficacy aiming at developing future mitigation strategies.
2025-02-14 | Transcriptomic analysis identifies muscle-specific mitochondrial and vesicular transport genes as methylmercury toxicity targets in a Drosophila model of congenital Minamata disease.
Prenatal methylmercury (MeHg) exposure presents a heightened concern in early human development, as has been exemplified in historic cases of congenital minimata disease (CMD). Children who experience CMD characteristically present with various degrees of cognitive and motor symptoms and signs, much like cerebral palsy. MeHg has thus been characterized as a neurotoxicant, where motor deficits are ascribed to central nervous system targets. Skeletal muscle as a post-synaptic MeHg target and contributor to the etiology of CMD has garnered far less attention. Prior studies using Drosophila to model CMD revealed that developmental exposure of MeHg in the larval/pupal stages can elicit graded and latent dose responses affecting adult flight behavior at lower doses (0.4-2.5 ppm in food) and eclosion (emergence from the pupa case) at higher doses (>2.5 ppm in food). The latter phenotype is accompanied by dysmorphogenesis of skeletal muscles. Here, we investigate respective roles for muscle and neural targets in MeHg toxicity. Using RNA-seq analysis, we find that developmental MeHg exposure produces 10 times as many differentially expressed transcripts in indirect flight muscle compared to the ventral nerve cord. Among known MeHg response genes, Nrf2 antioxidant response pathway genes showed muscle-specific MeHg-induced expression changes. Within the muscle transcriptome, the most enriched and significant Gene Ontology terms identified genes required for mitochondrial ribosomal translation at the pupa stage and mitochondrial function (respiratory chain complex I) and vesicle trafficking (ESCRT III) pathways in adults, all showing decreased expression with MeHg exposure. By using an intact, whole-animal developmental model, we identify preferential candidates to evaluate a novel role for muscle-specific mitochondria and intercellular vesicular communication mechanisms as targets in MeHg toxicity and the etiology of CMD.
2023-01-31 | Methylmercury Decreases AMPA Receptor Subunit GluA2 Levels in Cultured Rat Cortical Neurons
Methylmercury (MeHg) is a well-known environmental pollutant that has harmful effects on the central nervous systems of humans and animals. The molecular mechanisms of MeHg-induced neurotoxicity at low concentrations are not fully understood. Here, we investigated the effects of low-concentration MeHg on the cell viability, Ca2+ homeostasis, and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunit GluA2 levels, which determine Ca2+ permeability of AMPA receptors, in rat primary cortical neurons. Exposure of cortical neurons to 100 and 300 nM MeHg for 7 d resulted in a decrease in GluA2 levels, an increase in basal intracellular Ca2+ concentration, increased phosphorylation levels of extracellular signal-regulated kinase (ERK)1/2 and p38, and decreased cell viability. Moreover, glutamate stimulation exacerbated the decrease in cell viability and increased intracellular Ca2+ levels in MeHg-treated neurons compared to control neurons. MeHg-induced neuronal cell death was ameliorated by 1-naphthyl acetyl spermine, a specific antagonist of Ca2+-permeable, GluA2-lacking AMPA receptors. Our findings raise the possibility that decreased neuronal GluA2 levels and the subsequent increase in intracellular Ca2+ concentration may contribute to MeHg-induced neurotoxicity.
2021-06-03 | DHA ameliorates MeHg‑induced PC12 cell apoptosis by inhibiting the ROS/JNK signaling pathway
Recent studies have reported that methylmercury (MeHg) induces neuronal apoptosis, which is accompanied by abnormal neurological development. Despite the important role of docosahexaenoic acid (DHA) in maintaining the structure and function of the brain, as well as improving neuronal apoptosis induced by MeHg, the exact mechanism remains unknown. The present study hypothesized that the reactive oxygen species (ROS)‑mediated JNK signaling pathway may be associated with the protective effect of DHA against MeHg‑induced PC12 cell apoptosis. Cell Counting Kit‑8, TUNEL staining, flow cytometry, ROS detection, PCR and western blot analysis were performed. The results demonstrated that MeHg inhibited the activity of PC12 cells, causing oxidative damage and promoting apoptosis; however, DHA significantly attenuated this effect. Mechanistic studies revealed that MeHg increased intracellular ROS levels and JNK protein phosphorylation, and decreased the expression levels of the anti‑apoptotic protein Bcl‑2, whereas DHA reduced ROS levels and JNK phosphorylation, and increased Bcl‑2 expression. In addition, the ROS inhibitor N‑acetyl‑l‑cysteine (NAC) was used to verify the experimental results. After pretreatment with NAC, expression levels of Bcl‑2, Bax, phosphorylated‑JNK and JNK were assessed. Bcl‑2 protein expression was increased and the Bcl‑2/Bax ratio was increased. Moreover, the high expression levels of phosphorylated‑JNK induced by MeHg were significantly decreased. Based on the aforementioned results, the present study indicated that the effects of DHA against MeHg‑induced PC12 cell apoptosis may be mediated via the ROS/JNK signaling pathway.
2020-01-29 | Effects of Gintonin-Enriched Fraction on Methylmercury-Induced Neurotoxicity and Organ Methylmercury Elimination
Gintonin is a newly discovered ingredient of ginseng and plays an exogenous ligand for G protein-coupled lysophosphatidic acid receptors. We previously showed that gintonin exhibits diverse effects from neurotransmitter release to improvement of Alzheimer's disease-related cognitive dysfunctions. However, previous studies did not show whether gintonin has protective effects against environmental heavy metal. We investigated the effects of gintonin-enriched fraction (GEF) on methylmercury (MeHg)-induced neurotoxicity and learning and memory dysfunction and on organ MeHg elimination. Using hippocampal neural progenitor cells (hNPCs) and mice we examined the effects of GEF on MeHg-induced hippocampal NPC neurotoxicity, on formation of reactive oxygen species (ROS), and on in vivo learning and memory functions after acute MeHg exposure. Treatment of GEF to hNPCs attenuated MeHg-induced neurotoxicity with concentration- and time-dependent manner. GEF treatment inhibited MeHg- and ROS inducer-induced ROS formations. Long-term treatment of GEF also improved MeHg-induced learning and memory dysfunctions. Oral administration of GEF decreased the concentrations of MeHg in blood, brain, liver, and kidney. This is the first report that GEF attenuated MeHg-induced in vitro and in vivo neurotoxicities through LPA (lysophosphatidic acids) receptor-independent manner and increased organ MeHg elimination. GEF-mediated neuroprotection might achieve via inhibition of ROS formation and facilitation of MeHg elimination from body.
proteins
2026-03-02 | Long-term neurological and neurocognitive deficits in adults prenatally exposed to methylmercury: Minamata disease.
Minamata disease, officially recognized in 1956, is a well-known food poisoning event that was caused by the consumption of fish and seafood contaminated with methylmercury. Although patients with congenital Minamata disease (CMD) with severe neurological impairments after birth are widely recognized, few studies have examined the effects of prenatal methylmercury exposure among residents, which is likely at lower levels than in CMD patients. We aimed to investigate the relationship between prenatal methylmercury exposure and subsequent neurological and neurocognitive outcomes. We conducted a cross-sectional study during 2024-2025 among 51 individuals aged approximately 70 years, 27 residents from an existing cohort established in 1970 in Minamata and 24 age-matched individuals who had lived in less-exposed regions. We performed a battery of neurological and neurocognitive tests in both groups and compared the results using multiple linear regression analyses. We also examined the association between intelligence scores obtained in 1970, and intelligence scores obtained in the present investigation, only among exposed participants. We found that exposed individuals had unfavorable neurological and neurocognitive test scores, in comparison with less-exposed controls. Scores on the Montreal Cognitive Assessment, Japanese Edition were 5.91 points lower (95% confidence interval: 3.09 to 8.73) for exposed residents than for the less-exposed group. Moreover, intelligence scores evaluated during exposed participants' adolescence were correlated with their neurocognitive scores in adulthood. Our findings showed that prenatal methylmercury exposure affected subsequent neurological and neurocognitive functions, including among individuals with lower exposure than in CMD patients, and even approximately 70 years after the initial exposure.
2022-07-13 | In vivo evaluation of the potential protective effects of prolactin against damage caused by methylmercury
Non-biodegradable metals such as mercury accumulate in living organisms during life (bioaccumulation) and also within trophic webs (biomagnification) and may reach high concentrations in humans. The contamination of humans by mercury in drinking water and food may be common, in particular in riverside communities that have a diet rich in fish. In vitro studies of human cell lines exposed to the cytotoxic and mutagenic effects of methylmercury have shown that prolactin has potential cytoprotective properties and may act as a co-mitogenic factor and inhibitor of apoptosis. The present in vivo study investigated the protective potential of prolactin against the toxic effects of methylmercury in the mammal Mus musculus. Histological and biochemical analyses, together with biomarker of genotoxicity, were used to verify the protective potential of prolactin in mice exposed to methylmercury. The reduction in kidney and liver tissue damage was not significant. However, results of biochemical and genotoxic analyses were excellent. After prolactin treatment, a significant reduction was observed in biochemical parameters and mutagenic effects of methylmercury. The study results therefore indicated that prolactin has protective effects against the toxicity of methylmercury and allowed us to suggest the continuation of research to propose prolactin in the future, as an alternative to prevent the damage caused by mercury, especially in populations that are more exposed.
2021-09-21 | Neuroligin-1 Is a Mediator of Methylmercury Neuromuscular Toxicity
Abstract Methylmercury (MeHg) is a developmental toxicant capable of eliciting neurocognitive and neuromuscular deficits in children with in utero exposure. Previous research in Drosophila melanogaster uncovered that developmental MeHg exposure simultaneously targets the developing musculature and innervating motor neuron in the embryo, along with identifying Drosophila neuroligin 1 (nlg1) as a gene associated with developmental MeHg sensitivity. Nlg1 and its transsynaptic partner neurexin 1 (Nrx1) are critical for axonal arborization and NMJ maturation. We investigated the effects of MeHg exposure on indirect flight muscle (IFM) morphogenesis, innervation, and function via flight assays and monitored the expression of NMJ-associated genes to characterize the role of Nlg1 mediating the neuromuscular toxicity of MeHg. Developmental MeHg exposure reduced the innervation of the IFMs, which corresponded with reduced flight ability. In addition, nlg1 expression was selectively reduced during early metamorphosis, whereas a subsequent increase was observed in other NMJ-associated genes, including nrx1, in late metamorphosis. Developmental MeHg exposure also resulted in persistent reduced expression of most nlg and nrx genes during the first 11 days of adulthood. Transgenic modulation of nlg1 and nrx1 revealed that developing muscle is particularly sensitive to nlg1 levels, especially during the 20–36-h window of metamorphosis with reduced nlg1 expression resulting in adult flight deficits. Muscle-specific overexpression of nlg1 partially rescued MeHg-induced deficits in eclosion and flight. We identified Nlg1 as a muscle-specific, NMJ structural component that can mediate MeHg neuromuscular toxicity resulting from early life exposure.
2019-06-24 | Induction of chemokine CCL3 by NF-κB reduces methylmercury toxicity in C17.2 mouse neural stem cells
Methylmercury is an environmental pollutant that shows selective toxicity to the central nervous system. We previously reported that brain-specific expression of chemokine CCL3 increases in mice administered methylmercury. However, the relationship between CCL3 and methylmercury toxicity has not been elucidated. Here, we confirmed that induction of CCL3 expression occurs before pathological change by methylmercury treatment was observed in the mouse brain. This induction was also observed in C17.2 mouse neural stem cells before methylmercury-induced cytotoxicity. In addition, cells in which CCL3 was knocked-down showed higher methylmercury sensitivity than did control cells. Moreover, activation of transcription factor NF-κB was observed following methylmercury treatment, and methylmercury-mediated induction of CCL3 expression was partially suppressed by knockdown of p65, an NF-κB subunit. Our results suggest that NF-κB plays a role in the induction of methylmercury-mediated CCL3 expression and that this action may be a cellular response to methylmercury toxicity.
2012-04-20 | Oxoguanine Glycosylase 1 (OGG1) Protects Cells from DNA Double-Strand Break Damage Following Methylmercury (MeHg) Exposure
Methylmercury (MeHg) is a potent neurotoxin, teratogen, and probable carcinogen, but the underlying mechanisms of its actions remain unclear. Although MeHg causes several types of DNA damage, the toxicological consequences of this macromolecular damage are unknown. MeHg enhances oxidative stress, which can cause various oxidative DNA lesions that are primarily repaired by oxoguanine glycosylase 1 (OGG1). Herein, we compared the response of wild-type and OGG1 null (Ogg1–/–) murine embryonic fibroblasts to environmentally relevant, low micromolar concentrations of MeHg by measuring clonogenic efficiency, cell cycle arrest, DNA double-strand breaks (DSBs), and activation of the DNA damage response pathway.Ogg1–/– cells exhibited greater sensitivity to MeHg than wild-type controls, as measured by the clonogenic assay, and showed a greater propensity for MeHg-initiated apoptosis. Both wild-type and Ogg1–/– cells underwent cell cycle arrest when exposed to micromolar concentrations of MeHg; however, the extent of DSBs was exacerbated in Ogg1–/– cells compared with that in wild-type controls. Pretreatment with the antioxidative enzyme catalase reduced levels of DSBs in both wild-type and Ogg1–/– cells but failed to block MeHg-initiated apoptosis at micromolar concentrations. Our findings implicate reactive oxygen species mediated DNA damage in the mechanism of MeHg toxicity; and demonstrate for the first time that impaired DNA repair capacity enhances cellular sensitivity to MeHg. Accordingly, the genotoxic properties of MeHg may contribute to its neurotoxic and teratogenic effects, and an individual's response to oxidative stress and DNA damage may constitute an important determinant of risk.
small molecules
2025-07-21 | Thiamine Mitigates the Toxicity of Methylmercury in Cultured Fetal Fibroblast Cell Lines.
The challenge in addressing methylmercury (MeHg) poisoning primarily lies in devising effective therapeutic strategies. In this study, we explore the potential cytoprotective effects of thiamine pyrophosphate (TPP) as a novel agent to alleviate MeHg-induced complications. Fetal fibroblast cells were exposed to 100 µM MeHg with varying concentrations of TPP (12.5-100 mM). Treated and control cells were analyzed for determination of DNA and protein contents, whereas glutathione and lipid peroxidation levels were measured as oxidative stress markers. TPP reduced the cellular lipid peroxidation and restored the intracellular glutathione levels altered by MeHg, also increasing the cell DNA content in the 12.5 mM TPP treatment group. TPP treatment led to enhanced cell survival, underscoring TPP's capacity to alleviate MeHg toxicity by improving the antioxidant status. Further studies on additional oxidative stress markers and apoptotic pathways are necessary to fully elucidate the scope and mechanisms of TPP's cytoprotective effects against MeHg toxicity. While the data in this trial highlight the potential of TPP as a novel therapeutic agent for individuals exposed to MeHg, clinical studies are required to confirm its protective efficacy aiming at developing future mitigation strategies.
2025-02-14 | Transcriptomic analysis identifies muscle-specific mitochondrial and vesicular transport genes as methylmercury toxicity targets in a Drosophila model of congenital Minamata disease.
Prenatal methylmercury (MeHg) exposure presents a heightened concern in early human development, as has been exemplified in historic cases of congenital minimata disease (CMD). Children who experience CMD characteristically present with various degrees of cognitive and motor symptoms and signs, much like cerebral palsy. MeHg has thus been characterized as a neurotoxicant, where motor deficits are ascribed to central nervous system targets. Skeletal muscle as a post-synaptic MeHg target and contributor to the etiology of CMD has garnered far less attention. Prior studies using Drosophila to model CMD revealed that developmental exposure of MeHg in the larval/pupal stages can elicit graded and latent dose responses affecting adult flight behavior at lower doses (0.4-2.5 ppm in food) and eclosion (emergence from the pupa case) at higher doses (>2.5 ppm in food). The latter phenotype is accompanied by dysmorphogenesis of skeletal muscles. Here, we investigate respective roles for muscle and neural targets in MeHg toxicity. Using RNA-seq analysis, we find that developmental MeHg exposure produces 10 times as many differentially expressed transcripts in indirect flight muscle compared to the ventral nerve cord. Among known MeHg response genes, Nrf2 antioxidant response pathway genes showed muscle-specific MeHg-induced expression changes. Within the muscle transcriptome, the most enriched and significant Gene Ontology terms identified genes required for mitochondrial ribosomal translation at the pupa stage and mitochondrial function (respiratory chain complex I) and vesicle trafficking (ESCRT III) pathways in adults, all showing decreased expression with MeHg exposure. By using an intact, whole-animal developmental model, we identify preferential candidates to evaluate a novel role for muscle-specific mitochondria and intercellular vesicular communication mechanisms as targets in MeHg toxicity and the etiology of CMD.
2023-01-31 | Methylmercury Decreases AMPA Receptor Subunit GluA2 Levels in Cultured Rat Cortical Neurons
Methylmercury (MeHg) is a well-known environmental pollutant that has harmful effects on the central nervous systems of humans and animals. The molecular mechanisms of MeHg-induced neurotoxicity at low concentrations are not fully understood. Here, we investigated the effects of low-concentration MeHg on the cell viability, Ca2+ homeostasis, and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunit GluA2 levels, which determine Ca2+ permeability of AMPA receptors, in rat primary cortical neurons. Exposure of cortical neurons to 100 and 300 nM MeHg for 7 d resulted in a decrease in GluA2 levels, an increase in basal intracellular Ca2+ concentration, increased phosphorylation levels of extracellular signal-regulated kinase (ERK)1/2 and p38, and decreased cell viability. Moreover, glutamate stimulation exacerbated the decrease in cell viability and increased intracellular Ca2+ levels in MeHg-treated neurons compared to control neurons. MeHg-induced neuronal cell death was ameliorated by 1-naphthyl acetyl spermine, a specific antagonist of Ca2+-permeable, GluA2-lacking AMPA receptors. Our findings raise the possibility that decreased neuronal GluA2 levels and the subsequent increase in intracellular Ca2+ concentration may contribute to MeHg-induced neurotoxicity.
2021-06-03 | DHA ameliorates MeHg‑induced PC12 cell apoptosis by inhibiting the ROS/JNK signaling pathway
Recent studies have reported that methylmercury (MeHg) induces neuronal apoptosis, which is accompanied by abnormal neurological development. Despite the important role of docosahexaenoic acid (DHA) in maintaining the structure and function of the brain, as well as improving neuronal apoptosis induced by MeHg, the exact mechanism remains unknown. The present study hypothesized that the reactive oxygen species (ROS)‑mediated JNK signaling pathway may be associated with the protective effect of DHA against MeHg‑induced PC12 cell apoptosis. Cell Counting Kit‑8, TUNEL staining, flow cytometry, ROS detection, PCR and western blot analysis were performed. The results demonstrated that MeHg inhibited the activity of PC12 cells, causing oxidative damage and promoting apoptosis; however, DHA significantly attenuated this effect. Mechanistic studies revealed that MeHg increased intracellular ROS levels and JNK protein phosphorylation, and decreased the expression levels of the anti‑apoptotic protein Bcl‑2, whereas DHA reduced ROS levels and JNK phosphorylation, and increased Bcl‑2 expression. In addition, the ROS inhibitor N‑acetyl‑l‑cysteine (NAC) was used to verify the experimental results. After pretreatment with NAC, expression levels of Bcl‑2, Bax, phosphorylated‑JNK and JNK were assessed. Bcl‑2 protein expression was increased and the Bcl‑2/Bax ratio was increased. Moreover, the high expression levels of phosphorylated‑JNK induced by MeHg were significantly decreased. Based on the aforementioned results, the present study indicated that the effects of DHA against MeHg‑induced PC12 cell apoptosis may be mediated via the ROS/JNK signaling pathway.
2020-01-29 | Effects of Gintonin-Enriched Fraction on Methylmercury-Induced Neurotoxicity and Organ Methylmercury Elimination
Gintonin is a newly discovered ingredient of ginseng and plays an exogenous ligand for G protein-coupled lysophosphatidic acid receptors. We previously showed that gintonin exhibits diverse effects from neurotransmitter release to improvement of Alzheimer's disease-related cognitive dysfunctions. However, previous studies did not show whether gintonin has protective effects against environmental heavy metal. We investigated the effects of gintonin-enriched fraction (GEF) on methylmercury (MeHg)-induced neurotoxicity and learning and memory dysfunction and on organ MeHg elimination. Using hippocampal neural progenitor cells (hNPCs) and mice we examined the effects of GEF on MeHg-induced hippocampal NPC neurotoxicity, on formation of reactive oxygen species (ROS), and on in vivo learning and memory functions after acute MeHg exposure. Treatment of GEF to hNPCs attenuated MeHg-induced neurotoxicity with concentration- and time-dependent manner. GEF treatment inhibited MeHg- and ROS inducer-induced ROS formations. Long-term treatment of GEF also improved MeHg-induced learning and memory dysfunctions. Oral administration of GEF decreased the concentrations of MeHg in blood, brain, liver, and kidney. This is the first report that GEF attenuated MeHg-induced in vitro and in vivo neurotoxicities through LPA (lysophosphatidic acids) receptor-independent manner and increased organ MeHg elimination. GEF-mediated neuroprotection might achieve via inhibition of ROS formation and facilitation of MeHg elimination from body.
proteins
2026-03-02 | Long-term neurological and neurocognitive deficits in adults prenatally exposed to methylmercury: Minamata disease.
Minamata disease, officially recognized in 1956, is a well-known food poisoning event that was caused by the consumption of fish and seafood contaminated with methylmercury. Although patients with congenital Minamata disease (CMD) with severe neurological impairments after birth are widely recognized, few studies have examined the effects of prenatal methylmercury exposure among residents, which is likely at lower levels than in CMD patients. We aimed to investigate the relationship between prenatal methylmercury exposure and subsequent neurological and neurocognitive outcomes. We conducted a cross-sectional study during 2024-2025 among 51 individuals aged approximately 70 years, 27 residents from an existing cohort established in 1970 in Minamata and 24 age-matched individuals who had lived in less-exposed regions. We performed a battery of neurological and neurocognitive tests in both groups and compared the results using multiple linear regression analyses. We also examined the association between intelligence scores obtained in 1970, and intelligence scores obtained in the present investigation, only among exposed participants. We found that exposed individuals had unfavorable neurological and neurocognitive test scores, in comparison with less-exposed controls. Scores on the Montreal Cognitive Assessment, Japanese Edition were 5.91 points lower (95% confidence interval: 3.09 to 8.73) for exposed residents than for the less-exposed group. Moreover, intelligence scores evaluated during exposed participants' adolescence were correlated with their neurocognitive scores in adulthood. Our findings showed that prenatal methylmercury exposure affected subsequent neurological and neurocognitive functions, including among individuals with lower exposure than in CMD patients, and even approximately 70 years after the initial exposure.
2022-07-13 | In vivo evaluation of the potential protective effects of prolactin against damage caused by methylmercury
Non-biodegradable metals such as mercury accumulate in living organisms during life (bioaccumulation) and also within trophic webs (biomagnification) and may reach high concentrations in humans. The contamination of humans by mercury in drinking water and food may be common, in particular in riverside communities that have a diet rich in fish. In vitro studies of human cell lines exposed to the cytotoxic and mutagenic effects of methylmercury have shown that prolactin has potential cytoprotective properties and may act as a co-mitogenic factor and inhibitor of apoptosis. The present in vivo study investigated the protective potential of prolactin against the toxic effects of methylmercury in the mammal Mus musculus. Histological and biochemical analyses, together with biomarker of genotoxicity, were used to verify the protective potential of prolactin in mice exposed to methylmercury. The reduction in kidney and liver tissue damage was not significant. However, results of biochemical and genotoxic analyses were excellent. After prolactin treatment, a significant reduction was observed in biochemical parameters and mutagenic effects of methylmercury. The study results therefore indicated that prolactin has protective effects against the toxicity of methylmercury and allowed us to suggest the continuation of research to propose prolactin in the future, as an alternative to prevent the damage caused by mercury, especially in populations that are more exposed.
2021-09-21 | Neuroligin-1 Is a Mediator of Methylmercury Neuromuscular Toxicity
Abstract Methylmercury (MeHg) is a developmental toxicant capable of eliciting neurocognitive and neuromuscular deficits in children with in utero exposure. Previous research in Drosophila melanogaster uncovered that developmental MeHg exposure simultaneously targets the developing musculature and innervating motor neuron in the embryo, along with identifying Drosophila neuroligin 1 (nlg1) as a gene associated with developmental MeHg sensitivity. Nlg1 and its transsynaptic partner neurexin 1 (Nrx1) are critical for axonal arborization and NMJ maturation. We investigated the effects of MeHg exposure on indirect flight muscle (IFM) morphogenesis, innervation, and function via flight assays and monitored the expression of NMJ-associated genes to characterize the role of Nlg1 mediating the neuromuscular toxicity of MeHg. Developmental MeHg exposure reduced the innervation of the IFMs, which corresponded with reduced flight ability. In addition, nlg1 expression was selectively reduced during early metamorphosis, whereas a subsequent increase was observed in other NMJ-associated genes, including nrx1, in late metamorphosis. Developmental MeHg exposure also resulted in persistent reduced expression of most nlg and nrx genes during the first 11 days of adulthood. Transgenic modulation of nlg1 and nrx1 revealed that developing muscle is particularly sensitive to nlg1 levels, especially during the 20–36-h window of metamorphosis with reduced nlg1 expression resulting in adult flight deficits. Muscle-specific overexpression of nlg1 partially rescued MeHg-induced deficits in eclosion and flight. We identified Nlg1 as a muscle-specific, NMJ structural component that can mediate MeHg neuromuscular toxicity resulting from early life exposure.
2019-06-24 | Induction of chemokine CCL3 by NF-κB reduces methylmercury toxicity in C17.2 mouse neural stem cells
Methylmercury is an environmental pollutant that shows selective toxicity to the central nervous system. We previously reported that brain-specific expression of chemokine CCL3 increases in mice administered methylmercury. However, the relationship between CCL3 and methylmercury toxicity has not been elucidated. Here, we confirmed that induction of CCL3 expression occurs before pathological change by methylmercury treatment was observed in the mouse brain. This induction was also observed in C17.2 mouse neural stem cells before methylmercury-induced cytotoxicity. In addition, cells in which CCL3 was knocked-down showed higher methylmercury sensitivity than did control cells. Moreover, activation of transcription factor NF-κB was observed following methylmercury treatment, and methylmercury-mediated induction of CCL3 expression was partially suppressed by knockdown of p65, an NF-κB subunit. Our results suggest that NF-κB plays a role in the induction of methylmercury-mediated CCL3 expression and that this action may be a cellular response to methylmercury toxicity.
2012-04-20 | Oxoguanine Glycosylase 1 (OGG1) Protects Cells from DNA Double-Strand Break Damage Following Methylmercury (MeHg) Exposure
Methylmercury (MeHg) is a potent neurotoxin, teratogen, and probable carcinogen, but the underlying mechanisms of its actions remain unclear. Although MeHg causes several types of DNA damage, the toxicological consequences of this macromolecular damage are unknown. MeHg enhances oxidative stress, which can cause various oxidative DNA lesions that are primarily repaired by oxoguanine glycosylase 1 (OGG1). Herein, we compared the response of wild-type and OGG1 null (Ogg1–/–) murine embryonic fibroblasts to environmentally relevant, low micromolar concentrations of MeHg by measuring clonogenic efficiency, cell cycle arrest, DNA double-strand breaks (DSBs), and activation of the DNA damage response pathway.Ogg1–/– cells exhibited greater sensitivity to MeHg than wild-type controls, as measured by the clonogenic assay, and showed a greater propensity for MeHg-initiated apoptosis. Both wild-type and Ogg1–/– cells underwent cell cycle arrest when exposed to micromolar concentrations of MeHg; however, the extent of DSBs was exacerbated in Ogg1–/– cells compared with that in wild-type controls. Pretreatment with the antioxidative enzyme catalase reduced levels of DSBs in both wild-type and Ogg1–/– cells but failed to block MeHg-initiated apoptosis at micromolar concentrations. Our findings implicate reactive oxygen species mediated DNA damage in the mechanism of MeHg toxicity; and demonstrate for the first time that impaired DNA repair capacity enhances cellular sensitivity to MeHg. Accordingly, the genotoxic properties of MeHg may contribute to its neurotoxic and teratogenic effects, and an individual's response to oxidative stress and DNA damage may constitute an important determinant of risk.
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