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Ebrahimi M, Ebrahimi M, Vergroesen JE, Aschner M, Sillanpää M. Environmental exposures to cadmium and lead as potential causes of eye diseases. J Trace Elem Med Biol 2024; 82:127358. [PMID: 38113800 DOI: 10.1016/j.jtemb.2023.127358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 12/04/2023] [Accepted: 12/06/2023] [Indexed: 12/21/2023]
Abstract
Humans are exposed to cadmium and lead in various regions of the world daily due to industrial development and climate change. Increasing numbers of preclinical and clinical studies indicate that heavy metals, such as cadmium and lead, play a role in the pathogenesis of eye diseases. Excessive exposure to heavy metals such as cadmium and lead can increase the risk of impaired vision. Therefore, it is essential to better characterize the role of these non-essential metals in disease etiology and progression. This article discusses the potential role of cadmium and lead in the development of age-related eye diseases, including age-related macular degeneration, cataracts, and glaucoma. Furthermore, we discuss how cadmium and lead affect ocular cells and provide an overview of putative pathological mechanisms associated with their propensity to damage the eye.
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Affiliation(s)
- Moein Ebrahimi
- School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Network of Immunity in Infection, Malignancy, and Autoimmunity, Universal Scientific Education and Research Network (USERN), Tehran, Iran
| | - Maryam Ebrahimi
- Cancer Immunology Project (CIP), Universal Scientific Education and Research Network (USERN), Tehran, Iran
| | - Joëlle E Vergroesen
- Department of Ophthalmology, Erasmus MC University Medical Center, PO Box 2040, 3000 CA Rotterdam, the Netherlands; Department of Epidemiology, Erasmus MC University Medical Center, PO Box 2040, 3000 CA Rotterdam, the Netherlands.
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Mika Sillanpää
- Department of Chemical Engineering, School of Mining, Metallurgy and Chemical Engineering, University of Johannesburg, P. O. Box 17011, Doornfontein 2028, South Africa; International Research Centre of Nanotechnology for Himalayan Sustainability (IRCNHS), Shoolini University, Solan 173212, Himachal Pradesh, India; Zhejiang Rongsheng Environmental Protection Paper Co. LTD, NO.588 East Zhennan Road, Pinghu Economic Development Zone, Zhejiang 314213, PR China; Department of Civil Engineering, University Centre for Research & Development, Chandigarh University, Gharuan, Mohali, Punjab, India
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Cybulska AM, Grochans S, Kamińska MS, Bosiacki M, Skonieczna-Żydecka K, Grochans E. Are cadmium and lead levels linked to the development of anxiety and depression? - A systematic review of observational studies. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 216:112211. [PMID: 33862435 DOI: 10.1016/j.ecoenv.2021.112211] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 03/19/2021] [Accepted: 03/29/2021] [Indexed: 06/12/2023]
Abstract
The aim of this systematic review was to assess if cadmium and lead levels are linked to anxiety and depression. A systematic literature search was conducted to identify observational trials evaluating the impact of cadmium and lead on the incidence and phenotype of depression and anxiety. The search identified 1059 records. Overall eighteen studies comprising 28,304 participants with a female predominance (n = 19,483; 69%) were included. Cadmium and lead levels were analyzed in eight and thirteen studies, respectively. Five studies found an association between blood cadmium levels and depression, among them three trials which reported that individuals in the highest quartile of blood cadmium had higher odds of showing depressive symptoms. Sex and smoking status were found to be potential confounders of cadmium impact on the depressive phenotype. None of the studies found association between the level of anxiety and blood cadmium levels. Nine studies demonstrated association between depressive symptoms and blood lead concentration. High lead levels may be associated with anxiety and neurobehavioral deficits. There are many factors that influence both the levels of cadmium and lead, and the severity of depression and anxiety in the respondents. There is no clear evidence for the impact of cadmium and lead levels on the development of depressive symptoms but a lot of indirect evidence points to this.
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Affiliation(s)
- Anna Maria Cybulska
- Department of Nursing, Faculty of Health Sciences, Pomeranian Medical University in Szczecin, 48 Żołnierska St., 71-210 Szczecin, Poland.
| | - Szymon Grochans
- Department of Biochemistry and Medical Chemistry, Pomeranian Medical University in Szczecin, 72 Powstańców Wielkopolskich St., 70-111, Szczecin, Poland.
| | - Magdalena Sylwia Kamińska
- Subdepartment of Long-Term Care and Palliative Medicine, Department of Social Medicine, Faculty of Health Sciences, Pomeranian Medical University in Szczecin, 48 Żołnierska St., 71-210 Szczecin, Poland.
| | - Mateusz Bosiacki
- Department of Functional Diagnostics and Physical Medicine, Pomeranian Medical University in Szczecin, Żołnierska 54 Str., 71-210 Szczecin, Poland.
| | - Karolina Skonieczna-Żydecka
- Department of Human Nutrition and Metabolomics, Pomeranian Medical University in Szczecin, 24 Broniewskiego St., 71-460 Szczecin, Poland.
| | - Elżbieta Grochans
- Department of Nursing, Faculty of Health Sciences, Pomeranian Medical University in Szczecin, 48 Żołnierska St., 71-210 Szczecin, Poland.
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Hoffman JF, Vergara VB, Kalinich JF. Brain region- and metal-specific effects of embedded metals in a shrapnel wound model in the rat. Neurotoxicology 2021; 83:116-128. [PMID: 33453298 DOI: 10.1016/j.neuro.2021.01.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 01/03/2021] [Accepted: 01/03/2021] [Indexed: 02/07/2023]
Abstract
The health effects of prolonged exposure to embedded metal fragments, such as those found in shrapnel wounds sustained by an increasing number of military personnel, are not well known. As part of a large collaborative effort to expand this knowledge, we use an animal model of shrapnel wounds originally developed to investigate effects of embedded depleted uranium to investigate effects of military-relevant metals tungsten, nickel, cobalt, iron, copper, aluminum, lead, and depleted uranium compared to an inert control, tantalum. Rats are surgically implanted with pellets of one of the metals of interest in the gastrocnemius (leg) muscle and tracked until 1 month, 3 months, 6 months, or 12 months from the time of implant, at which point they are euthanized and multiple organs and tissue samples are collected for inspection. Here we focus on four regions of the brain: frontal cortex, hippocampus, amygdala, and cerebellum. We examined changes in accumulated metal concentration in each region as well as changes in expression of proteins related to blood brain barrier tight junction formation, occludin and ZO-1, and synapse function, PSD95, spinophilin, and synaptotagmin. We report few changes in metal accumulation or blood brain barrier protein expression, but a large number of synapse proteins have reduced expression levels, particularly within the first 6 months of exposure, but there are regional and metal-specific differences in effects.
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Affiliation(s)
- Jessica F Hoffman
- Internal Contamination and Metal Toxicity Program, Armed Forces Radiobiology Research Institute, Uniformed Services University, Bethesda, MD, USA
| | - Vernieda B Vergara
- Internal Contamination and Metal Toxicity Program, Armed Forces Radiobiology Research Institute, Uniformed Services University, Bethesda, MD, USA
| | - John F Kalinich
- Internal Contamination and Metal Toxicity Program, Armed Forces Radiobiology Research Institute, Uniformed Services University, Bethesda, MD, USA.
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Hoffman JF, Kalinich JF. Effects of Incubation of Human Brain Microvascular Endothelial Cells and Astrocytes with Pyridostigmine Bromide, DEET, or Permethrin in the Absence or Presence of Metal Salts. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17228336. [PMID: 33187257 PMCID: PMC7696739 DOI: 10.3390/ijerph17228336] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 11/05/2020] [Accepted: 11/09/2020] [Indexed: 12/19/2022]
Abstract
Gulf War Illness (GWI) is a chronic, multi-symptom illness suffered by over one-third of American military veterans who served in the Persian Gulf War between 1990 and 1991. No current single-exposure scenario accounts for all the symptoms observed in GWI, and instead may be due to a multi-exposure scenario. As a larger effort to understand how one category of multi-exposure scenarios of organic compounds such as nerve gas prophylactic pyridostigmine bromide, or insecticides/pesticides such as N,N-diethyl-m-toluamide (DEET) and permethrin, plus heavy metals found in inhaled dust particles (Al, Fe, Ni, Sr, DU, Co, Cu, Mn, and Zn) might play a role in neural aspects of GWI, we begin this initial study to examine the toxicity and oxidative damage markers of human brain endothelial cell and human astrocyte cell cultures in response to these compounds. A battery of cytotoxicity assessments, including the MTT assay, Neutral Red uptake, and direct microscopic observation, was used to determine a non-toxic dose of the test compounds. After testing a wide range of doses of each compound, we chose a sub-toxic dose of 10 µM for the three organic compounds and 1 µM for the nine metals of interest for co-exposure experiments on cell cultures and examined an array of oxidative stress-response markers including nitric oxide production, formation of protein carbonyls, production of thiobarbituric acid-reactive substances, and expression of proteins involved in oxidative stress and cell damage. Many markers were not significantly altered, but we report a significant increase in nitric oxide after exposure to any of the three compounds in conjunction with depleted uranium.
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Ingrassia R, Garavaglia B, Memo M. DMT1 Expression and Iron Levels at the Crossroads Between Aging and Neurodegeneration. Front Neurosci 2019; 13:575. [PMID: 31231185 PMCID: PMC6560079 DOI: 10.3389/fnins.2019.00575] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 05/20/2019] [Indexed: 12/15/2022] Open
Abstract
Iron homeostasis is an essential prerequisite for metabolic and neurological functions throughout the healthy human life, with a dynamic interplay between intracellular and systemic iron metabolism. The development of different neurodegenerative diseases is associated with alterations of the intracellular transport of iron and heavy metals, principally mediated by Divalent Metal Transporter 1 (DMT1), responsible for Non-Transferrin Bound Iron transport (NTBI). In addition, DMT1 regulation and its compartmentalization in specific brain regions play important roles during aging. This review highlights the contribution of DMT1 to the physiological exchange and distribution of body iron and heavy metals during aging and neurodegenerative diseases. DMT1 also mediates the crosstalk between central nervous system and peripheral tissues, by systemic diffusion through the Blood Brain Barrier (BBB), with the involvement of peripheral iron homeostasis in association with inflammation. In conclusion, a survey about the role of DMT1 and iron will illustrate the complex panel of interrelationship with aging, neurodegeneration and neuroinflammation.
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Affiliation(s)
- Rosaria Ingrassia
- Section of Biotechnologies, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Barbara Garavaglia
- Medical Genetics and Neurogenetics Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Maurizio Memo
- Section of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
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Kalinich JF, Kasper CE. Are Internalized Metals a Long-term Health Hazard for Military Veterans? Public Health Rep 2016; 131:831-833. [PMID: 28123230 DOI: 10.1177/0033354916669324] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- John F Kalinich
- Internal Contamination and Metal Toxicity Program, Armed Forces Radiobiology Research Institute, Uniformed Services University, Bethesda, MD, USA
| | - Christine E Kasper
- Office of Nursing Services, US Department of Veterans Affairs, Bethesda, MD, USA; Daniel K. Inouye Graduate School of Nursing, Uniformed Services University, Bethesda, MD, USA
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Diverse functional roles of lipocalin-2 in the central nervous system. Neurosci Biobehav Rev 2015; 49:135-56. [DOI: 10.1016/j.neubiorev.2014.12.006] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 11/28/2014] [Accepted: 12/04/2014] [Indexed: 12/16/2022]
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Rai NK, Ashok A, Rai A, Tripathi S, Nagar GK, Mitra K, Bandyopadhyay S. Exposure to As, Cd and Pb-mixture impairs myelin and axon development in rat brain, optic nerve and retina. Toxicol Appl Pharmacol 2013; 273:242-58. [DOI: 10.1016/j.taap.2013.05.003] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2012] [Revised: 04/13/2013] [Accepted: 05/03/2013] [Indexed: 01/25/2023]
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Mohd-Padil H, Mohd-Adnan A, Gabaldón T. Phylogenetic analyses uncover a novel clade of transferrin in nonmammalian vertebrates. Mol Biol Evol 2012; 30:894-905. [PMID: 23258311 PMCID: PMC3603312 DOI: 10.1093/molbev/mss325] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Transferrin is a protein super-family involved in iron transport, a central process in cellular homeostasis. Throughout the evolution of vertebrates, transferrin members have diversified into distinct subfamilies including serotransferrin, ovotransferrin, lactoferrin, melanotransferrin, the inhibitor of carbonic anhydrase, pacifastin, and the major yolk protein in sea urchin. Previous phylogenetic analyses have established the branching order of the diverse transferrin subfamilies but were mostly focused on the transferrin repertoire present in mammals. Here, we conduct a comprehensive phylogenetic analysis of transferrin protein sequences in sequenced vertebrates, placing a special focus on the less-studied nonmammalian vertebrates. Our analyses uncover a novel transferrin clade present across fish, sauropsid, and amphibian genomes but strikingly absent from mammals. Our reconstructed scenario implies that this novel class emerged through a duplication event at the vertebrate ancestor, and that it was subsequently lost in the lineage leading to mammals. We detect footprints of accelerated evolution following the duplication event, which suggest positive selection and early functional divergence of this novel clade. Interestingly, the loss of this novel class of transferrin in mammals coincided with the divergence by duplication of lactoferrin and serotransferrin in this lineage. Altogether, our results provide novel insights on the evolution of iron-binding proteins in the various vertebrate groups.
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Affiliation(s)
- Hirzahida Mohd-Padil
- School of Biosciences & Biotechnology, Faculty of Science Technology, Universiti Kebangsaan Malaysia, Selangor, Malaysia
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Rahman A, Khan KM, Al-Khaledi G, Khan I, Attur S. Early postnatal lead exposure induces tau phosphorylation in the brain of young rats. ACTA BIOLOGICA HUNGARICA 2012; 63:411-25. [PMID: 23134599 DOI: 10.1556/abiol.63.2012.4.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Cognitive impairment is a common feature of both lead exposure and hyperphosphorylation of tau. We, therefore, investigated whether lead exposure would induce tau hyperphosphorylation. Wistar rat pups were exposed to 0.2% lead acetate via their dams' drinking water from postnatal day 1 to 21. Lead in blood and brain were measured by atomic absorption spectrophotometry and the expression of tau, phosphorylated tau and various serine/threonine protein phosphatases (PP1, PP2A, PP2B and PP5) in the brain was analyzed by Western blot. Lead exposure significantly impaired learning and resulted in a significant reduction in the expression of tau but increased the phosphorylation of tau at Ser199/202, Thr212/Ser214 and Thr231. PP2A expression decreased, whereas, PP1 and PP5 expression increased in lead-exposed rats. These results demonstrate that early postnatal exposure to lead decrease PP2A expression and induce tau hyperphosphorylation at several serine and threonine residues. Hyperphosphorylation of tau may be a mechanism of Pb-induced deficits in learning and memory.
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Affiliation(s)
- A Rahman
- Department of Family Sciences, College for Women, Kuwait University, Kuwait.
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Expression and localization of the iron-siderophore binding protein lipocalin 2 in the normal rat brain and after kainate-induced excitotoxicity. Neurochem Int 2011; 59:591-9. [PMID: 21683107 DOI: 10.1016/j.neuint.2011.04.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 02/18/2011] [Accepted: 04/04/2011] [Indexed: 12/21/2022]
Abstract
Lipocalin 2 (LCN2) is produced by mammalian hosts to bind bacterial siderophore and sequester free iron as part of an innate immune response, and could also play a role in tissue iron homeostasis, but thus far, little is known about its expression in the CNS. The present study was carried out to study the expression of the lipocalin in the normal rat brain and after neuronal injury induced by kainate (KA). Low levels of LCN2 mRNA and protein expression were detected in most regions of the normal brain except the olfactory bulb, brainstem and cerebellum. KA lesions resulted in damage to the hippocampus, leading to an early increase at three days and a sustained elevation in LCN2 mRNA level of 16-fold, and protein expression at 80-fold in the lesioned tissue compared to controls at 2 weeks post-KA injection. The sustained elevation in mRNA expression was not detected among other lipocalins surveyed using real-time RT-PCR - apoD, PGDS, Rbp4 and LCN5. Single and double immunostaining confirmed that LCN2 is present in astrocytes in the olfactory bulb, brainstem and cerebellum of the normal brain, and reactive astrocytes in the KA-lesioned hippocampus. In conclusion, the present study showed LCN2 to be present in select brain regions, and is upregulated in astrocytes after neuronal injury induced by kainate. We postulate that, as in the periphery, LCN2 may have a role in iron transport or trafficking in the CNS.
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Abstract
It is well established that lead (Pb) exposure in humans leads to learning and memory impairment. However, the biological and molecular mechanisms are still not clearly understood. When over activated, serine/threonine protein phosphatases are known to function as a constraint on learning and memory. Activation of these phosphatases can also result in cytoskeletal changes that will adversely affect learning and memory. We investigated the effects of Pb exposure on these phosphatases in primary cultures of human neurons. Neurons were exposed to physiologically relevant concentrations of Pb (5, 10, 20 and 40 μg/dL) and total phosphatase and PP2A activities were determined in neuronal lysate using para-nitrophenyl phosphate (pNPP), and a PP2A-specific phosphopeptide as substrates. Expression of various serine/threonine phosphatases, tau and its phosphorylation state were determined by Western blot (WB) and immunocytochemistry (ICC). We found that the total phosphatase activity in the neuronal lysate was increased by 30–50% by all the concentrations of Pb tested. PP2A activity was increased by 5 μg/dL Pb only. PP1 expression was increased (ranging from 25–50%) by 10, 20 and 40 μg/dL of Pb. PP2B expression was increased substantially (up to 2.5-fold) by 10 μg/dL Pb, whereas, higher concentrations did not show any effect. On the other hand, Pb (at all concentrations used) decreased expression of PP2A and PP5. Pb exposure induced substantial hyperphosphorylation of tau at serine 199/202 by 5 and 10 μg/dL Pb, and Threonine 231 at higher doses. Expression of total tau was mostly unaffected by lead. Immunocytochemistry data confirmed the WB results of expression of PP1, PP2A, tau protein and the phosphorylation of tau. These results support our hypothesis that Pb exposure up regulates some of the serine/threonine phosphatases (PP1 and PP2B) that are known to impair memory formation, and suggest a novel mechanism of Pb neurotoxicity.
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Rai A, Maurya SK, Khare P, Srivastava A, Bandyopadhyay S. Characterization of developmental neurotoxicity of As, Cd, and Pb mixture: synergistic action of metal mixture in glial and neuronal functions. Toxicol Sci 2010; 118:586-601. [PMID: 20829427 DOI: 10.1093/toxsci/kfq266] [Citation(s) in RCA: 134] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Neurotoxicity of individual metals is well investigated but that of metal mixture (MM), an environmental reality, in the developing brain is relatively obscure. We investigated the combinatorial effect of arsenic (As), cadmium (Cd), and lead (Pb) on rat brain development, spanning in utero to postnatal development. MM was administered by gavage to pregnant and lactating rats, and to postweaning pups till 2 months. The pups exhibited behavioral disturbances characterized by hyperlocomotion, increased grip strength, and learning-memory deficit. Disruption of the blood-brain barrier (BBB) was associated with dose-dependent increase in deposition of the metals in developing brain. Astrocytes were affected by MM treatment as evident from their reduced density, area, perimeter, compactness, and number of processes, and increased apoptosis in cerebral cortex and cerebellum. The metals induced synergistic reduction in glial fibrillary acidic protein (GFAP) expression during brain development; however, postweaning withdrawal of MM partially restored the levels of GFAP in adults. To characterize the toxic mechanism, we treated rat primary astrocytes with MM at concentrations ranging from lethal concentration (LC)(10) to LC(75) of the metals. We observed synergistic downregulation in viability and increase in apoptosis of the astrocytes, which were induced by proximal activation of extra cellular signal-regulated kinase (ERK) signaling and downstream activation of Jun N-terminal kinase (JNK) pathway. Furthermore, rise in intracellular calcium ion ([Ca(2+)](i)) and reactive oxygen species generation promoted apoptosis in the astrocytes. Taken together, these observations are the first to show that mixture of As, Cd, and Pb has the capacity to induce synergistic toxicity in astrocytes that may compromise the BBB and may cause behavioral dysfunction in developing rats.
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Affiliation(s)
- Asit Rai
- Developmental Toxicology Division, Indian Institute of Toxicology Research, Council of Scientific and Industrial Research, Lucknow 226001, India
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Wang Q, Luo W, Zhang W, Liu M, Song H, Chen J. Involvement of DMT1 +IRE in the transport of lead in an in vitro BBB model. Toxicol In Vitro 2009; 25:991-8. [PMID: 19913089 DOI: 10.1016/j.tiv.2009.11.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Revised: 11/05/2009] [Accepted: 11/06/2009] [Indexed: 12/09/2022]
Abstract
Homeostasis of the central nervous system (CNS) microenvironment is maintained by the blood-brain barrier (BBB). The BBB is particularly vulnerable to lead (Pb) insults. This study was designed to test the hypothesis that divalent metal transporter 1 (DMT1), which is a divalent cation membrane transporter, was involved in transcellular transport across the BBB. An in vitro BBB model, which was a co-culture system of human umbilical vascular endothelial cells (ECV304) and rat glioma cells (C6), was established. Transendothelial electrical resistance (TEER) and fluoresceinisothiocyanate (FITC)-dextran permeability results showed that Pb exposure at the tested concentrations had no significant effects on intercellular tightness. Pb transport displayed properties that were associated with iron response element (IRE) positive isoform of DMT1. Accordingly, Pb transport was significantly blocked by iron (Fe). Moreover, ECV304 cells that were depleted of Fe with the chelator deferoxamine (DFO) demonstrated increased Pb transport. By transfecting ECV-304 cells with a DMT1 expression vector, overexpression of DMT1 promoted an increase in Pb transport. Treatment of ECV304 cells with DMT1 antisense oligonucleotides (ASONs) MA1 significantly inhibited the transport of Pb. Our results suggest that Pb is transported in the in vitro BBB model by a transporter with biochemical properties similar to those of the DMT1 IRE-positive isoform.
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Affiliation(s)
- Qiang Wang
- Department of Occupational and Environmental Health, School of Public Health and Military Preventive Medicine, Fourth Military Medical University, Xi'an, Shaanxi 710032, China
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