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Abdelhamid MS, El Bohi KM, Sherif MH, Abdelhamid MS, Abdel-Daim MM, Elewa YHA, Metwally MMM, Albadrani GM, Najda A, El Abdel-Hamid S, Abu-Zeid EH. Apitoxin alleviates methyl mercury-induced peripheral neurotoxicity in male rats by regulating dorsal root ganglia neuronal degeneration and oxidative stress. Biomed Pharmacother 2023; 161:114521. [PMID: 36921536 DOI: 10.1016/j.biopha.2023.114521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 03/02/2023] [Accepted: 03/09/2023] [Indexed: 03/16/2023] Open
Abstract
Methylmercury (MeHg) toxicity is associated with extensive neuronal degeneration of dorsal root ganglia (DRG). This study aimed to assess the ameliorative effect of bee venom (BV) on methyl mercury chloride (MeHgCl)-induced peripheral neurotoxicity using DRGs in rats. Forty-eight adult male Sprague Dawley rats were allocated into four equal groups: G I: control (gavaged MilliQ water 1 ml/rat), G II: subcutaneously injected with BV (0.5 mg/kg b.wt), G III: gavaged MeHgCl (6.7 mg/kg b.wt), and G IV: received MeHgCl+BV. Dosing was done five times/week for 2 weeks. Ataxic behavior and visual impairments were significantly increased, whereas the movement behavior and motility gait were suppressed in the MeHgCl group. MeHgCl significantly decreased total antioxidant capacity (TAC) in DRG and significantly decreased the serum levels of glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD). Tumor necrosis factor-alpha (TNF-α) and interleukin 1β (IL-1β) levels were significantly elevated, whereas interleukin 10 (IL-10) levels were significantly decreased in the MeHgCl group compared with the control group. DRGs of the MeHgCl-exposed rats showed pyknotic shrunken neurons with perineural vacuolations, demyelination of nerve axons, and proliferation of the satellite cells. MeHgCl significantly induced a higher positive index ratio of Iba-1, SOX10, neurofilament, pan-neuron, and vimentin immunostaining in the DRG. BV administration significantly mitigated the MeHgCl-induced alterations in oxidative stress-related indices. BV modified the immunostaining of Iba-1, SOX10, neurofilament, pan-neuron, and vimentin-positive index ratio in the DRG of the MeHgCl group. Our findings acknowledged that BV could enhance in vivo neuroprotective effects against MeHgCl-induced DRGs damage in male rats.
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Affiliation(s)
- Moustafa S Abdelhamid
- Biochemistry division, Chemistry Department, Faculty of Science, Zagazig University, 44511, Egypt
| | - Khlood M El Bohi
- Department of Forensic Medicine and Toxicology, Faculty of Veterinary Medicine, Zagazig University, 44511, Egypt
| | - Mohamed H Sherif
- Biochemistry division, Chemistry Department, Faculty of Science, Zagazig University, 44511, Egypt
| | - Manar S Abdelhamid
- Biochemistry division, Chemistry Department, Faculty of Science, Zagazig University, 44511, Egypt
| | - Mohamed M Abdel-Daim
- Department of Pharmaceutical Sciences, Pharmacy Program, Batterjee Medical College, P.O. Box 6231, Jeddah 21442, Saudi Arabia; Pharmacology Department, Faculty of Veterinary Medicine, Suez Canal University, Ismailia 41522, Egypt
| | - Yaser H A Elewa
- Department of Histology and Cytology, Faculty of Veterinary Medicine, Zagazig University, 44511, Egypt; Laboratory of Anatomy, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Mohamed M M Metwally
- Department of Pathology, Faculty of Veterinary Medicine, Zagazig University, Zagazig 44511, Egypt
| | - Ghadeer M Albadrani
- Department of Biology, College of Science, Princess Nourah bint Abdulrahman University, B.O. Box 84428, Riyadh 11671, Saudi Arabia
| | - Agnieszka Najda
- Department of Vegetable Crops and Medicinal Plants University of Life Sciences in Lublin, 50 A Doświadczalna Street, 20-280 Lublin, Poland.
| | - Shereen El Abdel-Hamid
- Department of Behavior and Management of Animal, Poultry and Aquatics, Faculty of Veterinary Medicine, Zagazig University, 44511, Egypt
| | - Ehsan H Abu-Zeid
- Department of Forensic Medicine and Toxicology, Faculty of Veterinary Medicine, Zagazig University, 44511, Egypt.
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2
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Bodienkova GM, Boklazhenko EV. Comparative Assessment of Neurochemical Indices in Patients with Occupational Pathology Caused by Physical and Chemical Factors. NEUROCHEM J+ 2021. [DOI: 10.1134/s1819712421040024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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3
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Shinoda Y, Yamada Y, Yoshida E, Takahashi T, Tsuneoka Y, Eto K, Kaji T, Fujiwara Y. Hypoalgesia and recovery in methylmercury-exposed rats. J Toxicol Sci 2021; 46:303-309. [PMID: 34078837 DOI: 10.2131/jts.46.303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Methylmercury (MeHg), the causal substrate in Minamata disease, can lead to severe and chronic neurological disorders. The main symptom of Minamata disease is sensory impairment in the four extremities; however, the sensitivity of individual sensory modalities to MeHg has not been investigated extensively. In the present study, we performed stimulus-response behavioral experiments in MeHg-exposed rats to compare the sensitivities to pain, heat, cold, and mechanical sensations. MeHg (6.7 mg/kg/day) was orally administered to 9-week-old Wistar rats for 5 days and discontinued for 2 days, then administered daily for another 5 days. The four behavioral experiments were performed daily on each rat from the beginning of MeHg treatment for 68 days. The pain sensation decreased significantly from day 11 onwards, but recovered to control levels on day 48. Other sensory modalities were not affected by MeHg exposure. These findings suggest that the pain sensation is the sensory modality most susceptive to MeHg toxicity and that this sensitivity is reversible following discontinuation of the exposure.
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Affiliation(s)
- Yo Shinoda
- Department of Environmental Health, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
| | - Yuta Yamada
- Department of Environmental Health, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
| | - Eiko Yoshida
- Department of Environmental Health, Faculty of Pharmaceutical Sciences, Tokyo University of Science
| | - Tsutomu Takahashi
- Department of Environmental Health, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
| | - Yayoi Tsuneoka
- Department of Environmental Health, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
| | - Komyo Eto
- Health and Nursing Facilities for the Aged, Jushindai, Shinwakai
| | - Toshiyuki Kaji
- Department of Environmental Health, Faculty of Pharmaceutical Sciences, Tokyo University of Science
| | - Yasuyuki Fujiwara
- Department of Environmental Health, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
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4
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Sceniak MP, Spitsbergen JB, Sabo SL, Yuan Y, Atchison WD. Acute neurotoxicant exposure induces hyperexcitability in mouse lumbar spinal motor neurons. J Neurophysiol 2020; 123:1448-1459. [PMID: 32159428 DOI: 10.1152/jn.00775.2019] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Spinal motor neurons (MNs) are susceptible to glutamatergic excitotoxicity, an effect associated with lumbar MN degeneration in amyotrophic lateral sclerosis (ALS). MN susceptibility to environmental toxicant exposure, one prospective contributor to sporadic ALS, has not been systematically studied. The goal of this study was to test the ability of a well-known environmental neurotoxicant to induce hyperexcitability in mouse lumbar MNs. Methylmercury (MeHg) causes neurotoxicity through mechanisms involving elevated intracellular Ca2+ concentration ([Ca2+]i), a hallmark of excitotoxicity. We tested whether acute exposure to MeHg induces hyperexcitability in MNs by altering synaptic transmission, using whole cell patch-clamp recordings of lumbar spinal MNs in vitro. Acute MeHg exposure (20 μM) led to an increase in the frequency of both spontaneous excitatory postsynaptic currents (EPSCs) and miniature EPSCs. The frequency of inhibitory postsynaptic currents (IPSCs) was also increased by MeHg. Action potential firing rates, both spontaneous and evoked, were increased by MeHg, despite increases in both EPSCs and IPSCs, indicating a shift toward hyperexcitability. Also consistent with hyperexcitability, fluo 4-AM microfluorimetry indicated that MeHg exposure induced an increase in [Ca2+]i. Spinal cord hyperexcitability is partially mediated by Ca2+-permeable AMPA receptors, as MeHg-dependent increases in EPSCs were blocked by 1-napthyl spermine. Therefore, spinal MNs appear highly susceptible to MeHg exposure, leading to significant increases in spontaneous network excitability and disruption of normal function. Prolonged hyperexcitability could lead to eventual neurodegeneration and loss of motor function as observed in spinal cord after MeHg exposure in vivo and may contribute to MeHg-induced acceleration of ALS symptoms.NEW & NOTEWORTHY Spinal motor neurons (MN) are susceptible to glutamatergic excitotoxicity, an effect associated with lumbar MN degeneration in amyotrophic lateral sclerosis (ALS). This study investigated MN susceptibility to environmental toxicant exposure, one prospective contributor to sporadic ALS. Spinal MNs appear highly susceptible to methylmercury exposure, leading to significant increases in spontaneous network excitability and disruption of normal function. Prolonged hyperexcitability could lead to neurodegeneration and loss of motor function as observed in ALS spinal cord symptoms.
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Affiliation(s)
- Michael P Sceniak
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan.,Department of Biology, Central Michigan University, Mount Pleasant, Michigan
| | - Jake B Spitsbergen
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - Shasta L Sabo
- Department of Biology, Central Michigan University, Mount Pleasant, Michigan
| | - Yukun Yuan
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - William D Atchison
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
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5
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Shinoda Y, Ehara S, Tatsumi S, Yoshida E, Takahashi T, Eto K, Kaji T, Fujiwara Y. Methylmercury-induced neural degeneration in rat dorsal root ganglion is associated with the accumulation of microglia/macrophages and the proliferation of Schwann cells. J Toxicol Sci 2019; 44:191-199. [PMID: 30842371 DOI: 10.2131/jts.44.191] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Exposure to organic mercury, especially methylmercury (MeHg), causes Minamata disease, a severe chronic neurological disorder. Minamata disease predominantly affects the central nervous system, and therefore, studies on the mechanisms of MeHg neurotoxicity have focused primarily on the brain. Although the peripheral nervous system is also affected by the organometallic compound and shows signs of neural degeneration, the mechanisms of peripheral MeHg neurotoxicity remain unclear. In the present study, we performed quantitative immunohistochemical analyses of the dorsal root ganglion (DRG) and associated sensory and motor fibers to clarify the mechanisms of MeHg-induced peripheral neurotoxicity in Wistar rats. Methylmercury chloride (6.7 mg/kg/day) was orally administrated for 5 days, followed by 2 days without administration, and this cycle was repeated once again. Seven and 14 days after the beginning of MeHg exposure, rats were anesthetized, and their DRGs and sensory and motor nerve fibers were removed and processed for immunohistochemical analyses. The frozen sections were immunostained for neuronal, Schwann cell, microglial and macrophage markers. DRG sensory neuron somata and axons showed significant degeneration on day 14. At the same time, an accumulation of microglia and the infiltration of macrophages were observed in the DRGs and sensory nerve fibers. In addition, MeHg caused significant Schwann cell proliferation in the sensory nerve fibers. In comparison, there was no noticeable change in the motor fibers. Our findings suggest that in the peripheral nervous system, MeHg toxicity is associated with neurodegenerative changes to DRG sensory neurons and the induction of a neuroprotective and/or enhancement of neurodegenerative host response.
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Affiliation(s)
- Yo Shinoda
- Department of Environmental Health, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
| | - Shunsuke Ehara
- Department of Environmental Health, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
| | - Satoshi Tatsumi
- Department of Environmental Health, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
| | - Eiko Yoshida
- Department of Environmental Health, Faculty of Pharmaceutical Sciences, Tokyo University of Science
| | - Tsutomu Takahashi
- Department of Environmental Health, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
| | - Komyo Eto
- Health and Nursing Facilities for the Aged, Jushindai, Shinwakai
| | - Toshiyuki Kaji
- Department of Environmental Health, Faculty of Pharmaceutical Sciences, Tokyo University of Science
| | - Yasuyuki Fujiwara
- Department of Environmental Health, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
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6
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Insights into the Potential Role of Mercury in Alzheimer's Disease. J Mol Neurosci 2019; 67:511-533. [PMID: 30877448 DOI: 10.1007/s12031-019-01274-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 01/30/2019] [Indexed: 12/18/2022]
Abstract
Mercury (Hg), which is a non-essential element, is considered a highly toxic pollutant for biological systems even when present at trace levels. Elevated Hg exposure with the growing release of atmospheric pollutant Hg and rising accumulations of mono-methylmercury (highly neurotoxic) in seafood products have increased its toxic potential for humans. This review aims to highlight the potential relationship between Hg exposure and Alzheimer's disease (AD), based on the existing literature in the field. Recent reports have hypothesized that Hg exposure could increase the potential risk of developing AD. Also, AD is known as a complex neurological disorder with increased amounts of both extracellular neuritic plaques and intracellular neurofibrillary tangles, which may also be related to lifestyle and genetic variables. Research reports on AD and relationships between Hg and AD indicate that neurotransmitters such as serotonin, acetylcholine, dopamine, norepinephrine, and glutamate are dysregulated in patients with AD. Many researchers have suggested that AD patients should be evaluated for Hg exposure and toxicity. Some authors suggest further exploration of the Hg concentrations in AD patients. Dysfunctional signaling pathways in AD and Hg exposure appear to be interlinked with some driving factors such as arachidonic acid, homocysteine, dehydroepiandrosterone (DHEA) sulfate, hydrogen peroxide, glucosamine glycans, glutathione, acetyl-L carnitine, melatonin, and HDL. This evidence suggests the need for a better understanding of the relationship between AD and Hg exposure, and potential mechanisms underlying the effects of Hg exposure on regional brain functions. Also, further studies evaluating brain functions are needed to explore the long-term effects of subclinical and untreated Hg toxicity on the brain function of AD patients.
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7
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Yamamoto M, Motomura E, Yanagisawa R, Hoang VAT, Mogi M, Mori T, Nakamura M, Takeya M, Eto K. Evaluation of neurobehavioral impairment in methylmercury-treated KK-Ay mice by dynamic weight-bearing test. J Appl Toxicol 2018; 39:221-230. [PMID: 30175511 DOI: 10.1002/jat.3710] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 06/21/2018] [Accepted: 07/11/2018] [Indexed: 12/22/2022]
Abstract
Methylmercury (MeHg) is known to cause neurobehavioral impairment in human and experimental animals. We previously reported that MeHg (5 mg Hg/kg) induced severe neurobehavioral dysfunction in 4-week-old KK-Ay mice, although it is difficult to evaluate quantitatively the neurobehavioral impairment in MeHg-treated KK-Ay mice because of their obesity. The aim of this study was to evaluate MeHg-induced neurobehavioral dysfunction in KK-Ay mice using the dynamic weight-bearing test, which analyzes the animal's weight distribution between the four limbs. Male 12-week-old KK-Ay mice were treated with MeHg (5 mg Hg/kg) three times per week for 5 weeks. Body weight loss began after approximately 2 weeks of MeHg treatment, and decreased significantly at 4 weeks. Seven of the nine MeHg-treated mice exhibited overt neurological symptoms such as ataxia and gait disturbance. The weight-bearing load was lower for the forelimb than for the hindlimb at baseline and until 1 week after MeHg treatment was initiated. In weeks 2-4, the dynamic weight-bearing loads on the forelimb and hindlimb were similar. The load on the forelimb exceeded the load on the hindlimb after 5 weeks of treatment. This finding indicates that the dynamic weight-bearing test is useful for semi-quantitative evaluation of neurobehavioral impairment in MeHg-treated rodents, and is less stressful for the animals. Infiltration of CD204-positive macrophages was observed in the sciatic nerve of MeHg-treated mice, suggesting that CD204 can serve as a useful marker of tissue injury in peripheral nerves and a possible target in regenerating peripheral nerves and controlling neuropathies.
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Affiliation(s)
- Megumi Yamamoto
- Integrated Physiology Section, Department of Basic Medical Science, National Institute for Minamata Disease, 4058-18 Hama, Minamata, Kumamoto, 867-0008, Japan
| | - Eriko Motomura
- Integrated Physiology Section, Department of Basic Medical Science, National Institute for Minamata Disease, 4058-18 Hama, Minamata, Kumamoto, 867-0008, Japan
| | - Rie Yanagisawa
- Center for Health and Environmental Risk Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki, 305-8506, Japan
| | - Van Anh Thi Hoang
- Integrated Physiology Section, Department of Basic Medical Science, National Institute for Minamata Disease, 4058-18 Hama, Minamata, Kumamoto, 867-0008, Japan.,Graduate School of Environmental and Symbiotic Science, Prefectural University of Kumamoto, 3-1-100 Tsukide, Higashi-ku, Kumamoto, 862-8502, Japan
| | - Masaki Mogi
- Department of Pharmacology, Ehime University Graduate School of Medicine, Ehime, 791-0295, Japan
| | - Tomohisa Mori
- Department of Pharmacology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, Tokyo, 142-8501, Japan
| | - Masaaki Nakamura
- Department of Clinical Medicine, National Institute for Minamata Disease, 4058-18 Hama, Minamata, Kumamoto, 867-0008, Japan
| | - Motohiro Takeya
- Department of Cell Pathology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto, 860-8556, Japan
| | - Komyo Eto
- Health and Nursing Facilities for the Aged, Jushindai, Shinwakai, 272 Ikurakitakata, Tamana, Kumamoto, 865-0041, Japan
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8
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Pellacani C, Costa LG. Role of autophagy in environmental neurotoxicity. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 235:791-805. [PMID: 29353798 DOI: 10.1016/j.envpol.2017.12.102] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 12/08/2017] [Accepted: 12/25/2017] [Indexed: 06/07/2023]
Abstract
Human exposure to neurotoxic pollutants (e.g. metals, pesticides and other chemicals) is recognized as a key risk factor in the pathogenesis of neurodegenerative disorders. Emerging evidence indicates that an alteration in autophagic pathways may be correlated with the onset of the neurotoxicity resulting from chronic exposure to these pollutants. In fact, autophagy is a natural process that permits to preserving cell homeostasis, through the seizure and degradation of the cytosolic damaged elements. However, when an excessive level of intracellular damage is reached, the autophagic process may also induce cell death. A correct modulation of specific stages of autophagy is important to maintain the correct balance in the organism. In this review, we highlight the critical role that autophagy plays in neurotoxicity induced by the most common classes of environmental contaminants. The understanding of this mechanism may be helpful to discover a potential therapeutic strategy to reduce side effects induced by these compounds.
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Affiliation(s)
- C Pellacani
- Dept. of Medicine and Surgery, University of Parma, Parma, Italy.
| | - L G Costa
- Dept. of Medicine and Surgery, University of Parma, Parma, Italy; Dept. of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
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9
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Sun B, Fan S, Yao K, Li Y, Huang X. Changes in intraepidermal nerve fiber and Langerhans cell densities in the plantar skin of rats after mercuric chloride exposure. J Peripher Nerv Syst 2017; 23:17-22. [PMID: 29168293 DOI: 10.1111/jns.12246] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 11/07/2017] [Accepted: 11/17/2017] [Indexed: 11/30/2022]
Abstract
Mercury and its compounds possess strong neurotoxicity and patients with mercury poisoning often report pain and numbness in the distal extremities that conform to the "stocking-glove" pattern. However, no study has investigated whether damage to small nerve fibers is associated with mercury poisoning. The aims of the present study were to evaluate the effects of different doses of mercury chloride (HgCl2 ) on intraepidermal nerve fibers density (IENFD) and Langerhans cells (LCs) in the plantar skin of rats and to assess the possible relationship between changes in IENFD and sensory testing. Male Sprague-Dawley rats were divided into three experimental groups and administered HgCl2 solutions via gavage at three different doses (4.25, 8.5, and 17 mg/kg/day) for 21 days. Subsequently, behavioral tests and pathological changes in IENFD and LCs were assessed at three different time points (1, 2, and 3 weeks). Rats in all three HgCl2 groups exhibited varying degrees of weight and hair loss. Thermal hypersensitivity was evident in all the HgCl2 groups (for middle-2w subgroup, p < 0.05). Mechanical sensitivity tests revealed hyposensitivity in all the HgCl2 groups except the high-1w subgroup. Significant decreases in IENFD (for the high-1w, middle-1w, low-2w, and low-3w subgroups, p < 0.05) and significant increases in the density of LCs (except for the low-1w and high-2w subgroups, all p < 0.05) were found in all groups after HgCl2 exposure. An association analysis revealed a significant correlation between the decrease in IENFD and the increase in LCs densities (r = -0.573, p < 0.01). The present study demonstrated a decrease in IENFD and an increase in LCs density in the plantar skin of rats after HgCl2 poisoning, indicating that damage of the small nerve fibers occurs after mercury poisoning.
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Affiliation(s)
- Binbin Sun
- Department of Neurology, Chinese PLA General Hospital, Beijing, P.R. China.,Department of Neurology, 307 Hospital, Chinese PLA, Beijing, P.R. China
| | - Shuangyi Fan
- Department of Neurology, 307 Hospital, Chinese PLA, Beijing, P.R. China
| | - Kai Yao
- Department of Neurology, 307 Hospital, Chinese PLA, Beijing, P.R. China
| | - Yifan Li
- Department of Neurology, The First Affiliated Hospital of Chinese PLA General Hospital, Beijing, P.R. China
| | - Xusheng Huang
- Department of Neurology, Chinese PLA General Hospital, Beijing, P.R. China
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10
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Sequestosome1/p62 protects mouse embryonic fibroblasts against low-dose methylercury-induced cytotoxicity and is involved in clearance of ubiquitinated proteins. Sci Rep 2017; 7:16735. [PMID: 29196648 PMCID: PMC5711938 DOI: 10.1038/s41598-017-17112-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 11/22/2017] [Indexed: 01/07/2023] Open
Abstract
Methylmercury (MeHg) is a widely distributed environmental pollutant that causes a series of cytotoxic effects. However, molecular mechanisms underlying MeHg toxicity are not fully understood. Here, we report that sequestosome1/p62 protects mouse embryonic fibroblasts (MEFs) against low-dose MeHg cytotoxicity via clearance of MeHg-induced ubiquitinated proteins. p62 mRNA and protein expression in MEFs were temporally induced by MeHg exposure p62-deficient MEFs exhibited higher sensitivity to MeHg exposure compared to their wild-type (WT) counterparts. An earlier and higher level of accumulation of ubiquitinated proteins was detected in p62-deficient cells compared with WT MEFs. Confocal microscopy revealed that p62 and ubiquitinated proteins co-localized in the perinuclear region of MEFs following MeHg treatment. Further analysis of MEFs revealed that ubiquitinated proteins co-localized with LC3-positive puncta upon co-treatment with MeHg and chloroquine, an autophagy inhibitor. In contrast, there was minimal co-localization in p62-deficient MEFs. The present study, for the first time, examined the expression and distribution of p62 and ubiquitinated proteins in cells exposed to low-dose MeHg. Our findings suggest that p62 is crucial for cytoprotection against MeHg-induced toxicity and is required for MeHg-induced ubiquitinated protein clearance.
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11
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Colón-Rodríguez A, Hannon HE, Atchison WD. Effects of methylmercury on spinal cord afferents and efferents-A review. Neurotoxicology 2017; 60:308-320. [PMID: 28041893 PMCID: PMC5447474 DOI: 10.1016/j.neuro.2016.12.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 12/21/2016] [Accepted: 12/21/2016] [Indexed: 10/20/2022]
Abstract
Methylmercury (MeHg) is an environmental neurotoxicant of public health concern. It readily accumulates in exposed humans, primarily in neuronal tissue. Exposure to MeHg, either acutely or chronically, causes severe neuronal dysfunction in the central nervous system and spinal neurons; dysfunction of susceptible neuronal populations results in neurodegeneration, at least in part through Ca2+-mediated pathways. Biochemical and morphologic changes in peripheral neurons precede those in central brain regions, despite the fact that MeHg readily crosses the blood-brain barrier. Consequently, it is suggested that unique characteristics of spinal cord afferents and efferents could heighten their susceptibility to MeHg toxicity. Transient receptor potential (TRP) ion channels are a class of Ca2+-permeable cation channels that are highly expressed in spinal afferents, among other sensory and visceral organs. These channels can be activated in numerous ways, including directly via chemical irritants or indirectly via Ca2+ release from intracellular storage organelles. Early studies demonstrated that MeHg interacts with heterologous TRP channels, though definitive mechanisms of MeHg toxicity on sensory neurons may involve more complex interaction with, and among, differentially-expressed TRP populations. In spinal efferents, glutamate receptors of the N-methyl-D-aspartate (NMDA), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), and possibly kainic acid (KA) classes are thought to play a major role in MeHg-induced neurotoxicity. Specifically, the Ca2+-permeable AMPA receptors, which are abundant in motor neurons, have been identified as being involved in MeHg-induced neurotoxicity. In this review, we will describe the mechanisms that could contribute to MeHg-induced spinal cord afferent and efferent neuronal degeneration, including the possible mediators, such as uniquely expressed Ca2+-permeable ion channels.
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Affiliation(s)
- Alexandra Colón-Rodríguez
- Department of Pharmacology and Toxicology, 1355 Bogue Street, Life Sciences Building Rm. B440, Michigan State University, East Lansing, MI, United States; Institute for Integrative Toxicology, 1129 Farm Lane, Food Safety and Toxicology Rm. 165, Michigan State University, East Lansing, MI, United States; Comparative Medicine and Integrative Biology Program, 784 Wilson Road, Veterinary Medical Center Rm. G-100, Michigan State University, East Lansing, MI, United States.
| | - Heidi E Hannon
- Department of Pharmacology and Toxicology, 1355 Bogue Street, Life Sciences Building Rm. B440, Michigan State University, East Lansing, MI, United States; Institute for Integrative Toxicology, 1129 Farm Lane, Food Safety and Toxicology Rm. 165, Michigan State University, East Lansing, MI, United States; Comparative Medicine and Integrative Biology Program, 784 Wilson Road, Veterinary Medical Center Rm. G-100, Michigan State University, East Lansing, MI, United States.
| | - William D Atchison
- Department of Pharmacology and Toxicology, 1355 Bogue Street, Life Sciences Building Rm. B440, Michigan State University, East Lansing, MI, United States; Institute for Integrative Toxicology, 1129 Farm Lane, Food Safety and Toxicology Rm. 165, Michigan State University, East Lansing, MI, United States; Comparative Medicine and Integrative Biology Program, 784 Wilson Road, Veterinary Medical Center Rm. G-100, Michigan State University, East Lansing, MI, United States.
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12
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Influence of a low dose of silver nanoparticles on cerebral myelin and behavior of adult rats. Toxicology 2016; 363-364:29-36. [PMID: 27427492 DOI: 10.1016/j.tox.2016.07.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 07/11/2016] [Accepted: 07/13/2016] [Indexed: 11/23/2022]
Abstract
Nanoscale particles have large surface to volume ratio that significantly enhances their chemical and biological reactivity. Although general toxicity of nano silver (nanoAg) has been intensively studied in both in vitro and in vivo models, its neurotoxic effects are poorly known, especially those of low-dose exposure. In the present study we assess whether oral administration of nanoAg influences behavior of exposed rats and induces changes in cerebral myelin. We examine the effect of prolonged exposure of adult rats to small (10nm) citrate-stabilized nanoAg particles at a low dose of 0.2mg/kg b.w. (as opposed to the ionic silver) in a comprehensive behavioral analysis. Myelin ultrastructure and the expression of myelin-specific proteins are also investigated. The present study reveals slight differences with respect to behavioral effects of Ag(+)- but not nanoAg-treated rats. A weak depressive effect and hyperalgesia were observed after Ag(+) exposure whereas administration of nanoAg was found to specifically increase body weight and body temperature of animals. Both nanoAg and Ag(+) induce morphological disturbances in myelin sheaths and alter the expression of myelin-specific proteins CNP, MAG and MOG. These results suggest that the CNS may be a target of low-level toxicity of nanoAg.
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Zhang Z, Miah M, Culbreth M, Aschner M. Autophagy in Neurodegenerative Diseases and Metal Neurotoxicity. Neurochem Res 2016; 41:409-22. [PMID: 26869037 DOI: 10.1007/s11064-016-1844-x] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 01/20/2016] [Accepted: 01/22/2016] [Indexed: 02/07/2023]
Abstract
Autophagy generally refers to cell catabolic and recycling process in which cytoplasmic components are delivered to lysosomes for degradation. During the last two decades, autophagy research has experienced a recent boom because of a newfound connection between this process and many human diseases. Autophagy plays a significant role in maintaining cellular homeostasis and protects cells from varying insults, including misfolded and aggregated proteins and damaged organelles, which is particularly crucial in neuronal survival. Mounting evidence has implicated autophagic dysfunction in the pathogenesis of several major neurodegenerative disorders, such as Parkinson's disease, Alzheimer's disease and Huntington's disease, where deficient elimination of abnormal and toxic protein aggregates promotes cellular stress, failure and death. In addition, autophagy has also been found to affect neurotoxicity induced by exposure to essential metals, such as manganese, copper, and iron, and other heavy metals, such as cadmium, lead, and methylmercury. This review examines current literature on the role of autophagy in the mechanisms of disease pathogenesis amongst common neurodegenerative disorders and of metal-induced neurotoxicity.
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Affiliation(s)
- Ziyan Zhang
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Forchheimer 209, Bronx, NY, 10461, USA
| | - Mahfuzur Miah
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Forchheimer 209, Bronx, NY, 10461, USA
| | - Megan Culbreth
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Forchheimer 209, Bronx, NY, 10461, USA
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Forchheimer 209, Bronx, NY, 10461, USA.
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Barbosa DJ, Capela JP, de Lourdes Bastos M, Carvalho F. In vitro models for neurotoxicology research. Toxicol Res (Camb) 2015; 4:801-842. [DOI: 10.1039/c4tx00043a] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023] Open
Abstract
The nervous system has a highly complex organization, including many cell types with multiple functions, with an intricate anatomy and unique structural and functional characteristics; the study of its (dys)functionality following exposure to xenobiotics, neurotoxicology, constitutes an important issue in neurosciences.
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Affiliation(s)
- Daniel José Barbosa
- REQUIMTE (Rede de Química e Tecnologia)
- Laboratório de Toxicologia
- Departamento de Ciências Biológicas
- Faculdade de Farmácia
- Universidade do Porto
| | - João Paulo Capela
- REQUIMTE (Rede de Química e Tecnologia)
- Laboratório de Toxicologia
- Departamento de Ciências Biológicas
- Faculdade de Farmácia
- Universidade do Porto
| | - Maria de Lourdes Bastos
- REQUIMTE (Rede de Química e Tecnologia)
- Laboratório de Toxicologia
- Departamento de Ciências Biológicas
- Faculdade de Farmácia
- Universidade do Porto
| | - Félix Carvalho
- REQUIMTE (Rede de Química e Tecnologia)
- Laboratório de Toxicologia
- Departamento de Ciências Biológicas
- Faculdade de Farmácia
- Universidade do Porto
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