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Xie J, Wu S, Szadowski H, Min S, Yang Y, Bowman AB, Rochet JC, Freeman JL, Yuan C. Developmental Pb exposure increases AD risk via altered intracellular Ca 2+ homeostasis in hiPSC-derived cortical neurons. J Biol Chem 2023; 299:105023. [PMID: 37423307 PMCID: PMC10413359 DOI: 10.1016/j.jbc.2023.105023] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 06/21/2023] [Accepted: 06/22/2023] [Indexed: 07/11/2023] Open
Abstract
Exposure to environmental chemicals such as lead (Pb) during vulnerable developmental periods can result in adverse health outcomes later in life. Human cohort studies have demonstrated associations between developmental Pb exposure and Alzheimer's disease (AD) onset in later life which were further corroborated by findings from animal studies. The molecular pathway linking developmental Pb exposure and increased AD risk, however, remains elusive. In this work, we used human iPSC-derived cortical neurons as a model system to study the effects of Pb exposure on AD-like pathogenesis in human cortical neurons. We exposed neural progenitor cells derived from human iPSC to 0, 15, and 50 ppb Pb for 48 h, removed Pb-containing medium, and further differentiated them into cortical neurons. Immunofluorescence, Western blotting, RNA-sequencing, ELISA, and FRET reporter cell lines were used to determine changes in AD-like pathogenesis in differentiated cortical neurons. Exposing neural progenitor cells to low-dose Pb, mimicking a developmental exposure, can result in altered neurite morphology. Differentiated neurons exhibit altered calcium homeostasis, synaptic plasticity, and epigenetic landscape along with elevated AD-like pathogenesis markers, including phosphorylated tau, tau aggregates, and Aβ42/40. Collectively, our findings provide an evidence base for Ca dysregulation caused by developmental Pb exposure as a plausible molecular mechanism accounting for increased AD risk in populations with developmental Pb exposure.
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Affiliation(s)
- Junkai Xie
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Shichen Wu
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Hailey Szadowski
- Agriculture and Biological Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Sehong Min
- Department of Medicinal Chemistry and Molecular Pharmacy, Purdue University, West Lafayette, Indiana, USA
| | - Yang Yang
- Department of Medicinal Chemistry and Molecular Pharmacy, Purdue University, West Lafayette, Indiana, USA; Purdue Institute of Integrated Neuroscience, Purdue University, West Lafayette, Indiana, USA
| | - Aaron B Bowman
- Purdue Institute of Integrated Neuroscience, Purdue University, West Lafayette, Indiana, USA; School of Health Sciences, Purdue University, West Lafayette, Indiana, USA
| | - Jean-Christophe Rochet
- Department of Medicinal Chemistry and Molecular Pharmacy, Purdue University, West Lafayette, Indiana, USA; Purdue Institute of Integrated Neuroscience, Purdue University, West Lafayette, Indiana, USA
| | - Jennifer L Freeman
- Purdue Institute of Integrated Neuroscience, Purdue University, West Lafayette, Indiana, USA; School of Health Sciences, Purdue University, West Lafayette, Indiana, USA; Purdue Center of Cancer Research, Purdue University, West Lafayette, Indiana, USA
| | - Chongli Yuan
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana, USA; Purdue Institute of Integrated Neuroscience, Purdue University, West Lafayette, Indiana, USA; Purdue Center of Cancer Research, Purdue University, West Lafayette, Indiana, USA.
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2
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Niu C, Dong M, Niu Y. Lead toxicity and potential therapeutic effect of plant-derived polyphenols. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2023; 114:154789. [PMID: 37004401 DOI: 10.1016/j.phymed.2023.154789] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 03/21/2023] [Accepted: 03/28/2023] [Indexed: 06/19/2023]
Abstract
BACKGROUND Due to its unique physical and chemical properties, lead is still used worldwide in several applications, especially in industry. Both environmental and industrial lead exposures remain a public health problem in many developing and rapidly industrializing countries. Plant polyphenols are pleiotropic in their function and have historically made a major contribution to pharmacotherapy. PURPOSE To summarize available pre-clinical and limited clinical evidence on plant polyphenols as potential antidotes against lead poisoning and discuss toxic mechanisms of lead. METHOD A comprehensive search of peer-reviewed publications was performed from core collections of electronic databases such as PubMed, Web of Science, Google Scholar, and Science Direct. Articles written in English-language from inception until December 2022 were selected. RESULTS In this review, we review key toxic mechanisms of lead and its pathological effects on the neurological, reproductive, renal, cardiovascular, hematological, and hepatic systems. We focus on plant polyphenols against lead toxicity and involved mechanisms. Finally, we address scientific gaps and challenges associated with translating these promising preclinical discoveries into effective clinical therapies. CONCLUSION While preclinical evidence suggests that plant polyphenols exhibit bioprotective effects against lead toxicity, scant and equivocal clinical data highlight a need for clinical trials with those polyphenols.
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Affiliation(s)
- Chengu Niu
- Internal medicine residency program, Rochester General Hospital, Rochester, NY 14621, USA
| | - Miaoxian Dong
- The Institute of Medicine, Qiqihar Medical University, Qiqihar 161006, China
| | - Yingcai Niu
- The Institute of Medicine, Qiqihar Medical University, Qiqihar 161006, China.
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3
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Marino V, Cortivo GD, Dell'Orco D. Ionic displacement of Ca 2+ by Pb 2+ in calmodulin is affected by arrhythmia-associated mutations. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119490. [PMID: 37201768 DOI: 10.1016/j.bbamcr.2023.119490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 04/14/2023] [Accepted: 05/10/2023] [Indexed: 05/20/2023]
Abstract
Lead is a highly toxic metal that severely perturbs physiological processes even at sub-micromolar levels, often by disrupting the Ca2+ signaling pathways. Recently, Pb2+-associated cardiac toxicity has emerged, with potential involvement of both the ubiquitous Ca2+ sensor protein calmodulin (CaM) and ryanodine receptors. In this work, we explored the hypothesis that Pb2+ contributes to the pathological phenotype of CaM variants associated with congenital arrhythmias. We performed a thorough spectroscopic and computational characterization of CaM conformational switches in the co-presence of Pb2+ and four missense mutations associated with congenital arrhythmias, namely N53I, N97S, E104A and F141L, and analyzed their effects on the recognition of a target peptide of RyR2. When bound to any of the CaM variants, Pb2+ is difficult to displace even under equimolar Ca2+ concentrations, thus locking all CaM variants in a specific conformation, which exhibits characteristics of coiled-coil assemblies. All arrhythmia-associated variants appear to be more susceptible to Pb2+ than WT CaM, as the conformational transition towards the coiled-coil conformation occurs at lower Pb2+, regardless of the presence of Ca2+, with altered cooperativity. The presence of arrhythmia-associated mutations specifically alters the cation coordination of CaM variants, in some cases involving allosteric communication between the EF-hands in the two domains. Finally, while wild type CaM increases the affinity for the RyR2 target in the presence of Pb2+, no specific pattern could be detected for all other variants, ruling out a synergistic effect of Pb2+ and mutations in the recognition process.
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Affiliation(s)
- Valerio Marino
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, I-37134 Verona, Italy
| | - Giuditta Dal Cortivo
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, I-37134 Verona, Italy
| | - Daniele Dell'Orco
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, I-37134 Verona, Italy.
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4
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Usende IL, Olopade JO, Azeez IA, Andrioli A, Bankole MO, Olopade FE, Nafady AA, Bentivoglio M. Neuroecotoxicology: Effects of environmental heavy metal exposure on the brain of African giant rats and the contribution of vanadium to the neuropathology. IBRO Neurosci Rep 2022; 13:215-234. [PMID: 36590095 PMCID: PMC9795313 DOI: 10.1016/j.ibneur.2022.08.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 08/26/2022] [Indexed: 01/04/2023] Open
Abstract
Increased exploitation of minerals has led to pollution of confined environments as documented in Nigeria Niger Delta. Information on the effects on brain of such exposure is limited. Due to its exploratory activities, the African giant rat (Cricetomys gambianus) (AGR) provides a unique model for neuroecotoxicological research to determine levels of animal and human exposure to different pollutants. This study aims to unravel neuropathological features of AGR sampled from three agro-ecological zones of Nigeria. Fifteen AGR were sampled according to previously determined data on heavy metal exposure: high vanadium, high lead, and low metals. Eighteen AGR were collected from low metal zone and divided into two groups. Control group received vehicle while SMV exposed group received 3 mg/kg sodium metavanadate (SMV) intraperitoneally for 14days. Brain immunohistochemical analyses were conducted, and ultrastructural changes were studied in experimentally exposed group. Results showed significant loss of tyrosin hydroxylase, parvalbumin, orexin-A and melanin concentration hormone containing neuronal populations in brains obtained from high vanadium and high lead zones and in experimentally intoxicated SMV groups. Similarly, significant decrease numbers of dendritic arborations; extracellular matrix density, perineuronal nets; astrocytes and microglia activations are documented in same groups. Ultrastructural studies revealed mass denudation, cilia loss, disintegration of ependymal layer and intense destructions of myelin sheaths in SMV exposed group. These are the first "neuroecotoxicological" findings in distinct neuronal cells. The implications of these findings are highly relevant for human population living in these areas, not only in Nigeria but also in similarly polluted areas elsewhere in the world.
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Affiliation(s)
- Ifukibot Levi Usende
- Department of Veterinary Anatomy, University of Abuja, Nigeria,Department of Veterinary Anatomy, University of Ibadan, Nigeria,Corresponding author at: Department of Veterinary Anatomy, University of Abuja, Nigeria.
| | | | | | - Anna Andrioli
- Department of Neurological and Movement Sciences, University of Verona, Italy
| | - Molakun O. Bankole
- Department of Neurological and Movement Sciences, University of Verona, Italy
| | | | - Allam A. Nafady
- Department of Veterinary Pathology, Electron Microscope Unit, Assuit University, Egypt
| | - Marina Bentivoglio
- Department of Neurological and Movement Sciences, University of Verona, Italy
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5
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Sharma N. Schiff bases bearing amino acids for selective detection of Pb2+ ions in aqueous medium. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2021.139280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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The Blood Lead Levels of Children and the Loss of Ca 2+ from Neurons Owing to Lead. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph182212051. [PMID: 34831808 PMCID: PMC8625248 DOI: 10.3390/ijerph182212051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 11/11/2021] [Accepted: 11/15/2021] [Indexed: 11/17/2022]
Abstract
In order to understand current blood lead levels (BLLs), we investigated the BLLs of children in Sichuan Province from 2011 to 2020. We then monitored the treatment effects of calcium in children with high BLLs to assess their treatment status. Finally, we explored the effects of lead on Ca2+ through in-situ experiments. Whole blood samples were used for BLL tests. The BLLs of 76,362 children aged 0-7 years were measured using atomic absorption spectrometry. The median BLL was 35 μg/L (interquartile range: 28-47). The BLLs were significantly higher in boys than in girls (p < 0.001). The BLLs generally decreased annually and increased with age. The overall prevalence of BLLs ≥ 100 μg/L was 1.20%. The children with high BLLs received subsequent check-ups, and the median time required for effective treatment was 18 months. We observed that lead exposure led to a gradual and persistent loss of Ca2+ levels in neurons of mice brain slices, and the effect did not subside immediately even after the lead was removed. China has made rapid progress in pediatric healthcare, but the treatment status remains unsatisfactory. Because lead causes an irreversible loss of Ca2+, there is an urgent need to develop new standardized treatments to reduce the treatment duration.
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Liu F, Wang Z, Wei Y, Liu R, Jiang C, Gong C, Liu Y, Yan B. The leading role of adsorbed lead in PM 2.5-induced hippocampal neuronal apoptosis and synaptic damage. JOURNAL OF HAZARDOUS MATERIALS 2021; 416:125867. [PMID: 34492814 DOI: 10.1016/j.jhazmat.2021.125867] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 03/22/2021] [Accepted: 04/08/2021] [Indexed: 06/13/2023]
Abstract
Neurodegenerative diseases may be caused by air pollution, such as PM2.5. However, particles still need to be elucidated the mechanism of synergistic neurotoxicity induced by pollutant-loading PM2.5. In this study, we used a reductionist approach to study leading role of lead (Pb) in PM2.5-induced hippocampal neuronal apoptosis and synaptic damage both in vivo and in vitro. Pb in PM2.5 caused neurotoxicity: 1) by increasing ROS levels and thus causing apoptosis in neuronal cells and 2) by decreasing the expression of PSD95 via interfering with the calcium signaling pathway through cAMP/CREB/pCREB/BDNF/PSD95 pathway and reducing the synapse length by 50%. This study clarifies a key factor in PM2.5-induced neurotoxicity and provides the experimental basis for reducing PM2.5-induced neurotoxicity.
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Affiliation(s)
- Fang Liu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
| | - Zengjin Wang
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
| | - Yongyi Wei
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
| | - Rongrong Liu
- Institute of Environmental Research at Greater Bay Area, Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou 510006, China
| | - Cuijuan Jiang
- School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China
| | - Chen Gong
- School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China
| | - Yin Liu
- School of Environment, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 330106, China.
| | - Bing Yan
- Institute of Environmental Research at Greater Bay Area, Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou 510006, China; School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China.
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8
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Sharma N, Gulati A. Pb 2+ sensing by coumarin sulphonamide hybrids in aqueous medium. LUMINESCENCE 2021; 36:1172-1180. [PMID: 33713392 DOI: 10.1002/bio.4042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 03/06/2021] [Accepted: 03/08/2021] [Indexed: 01/07/2023]
Abstract
Metals play an important role in various metabolic activities in the human body, but above desired concentrations, a role reversal occurs that causes deadly outcomes viz., cancer. Metals cannot be cracked down and are non-biodegradable. It is the bioaccumulation of toxic metals inside the biomatrices, that further intensifies the research on different means of metal detoxification from different matrices. Among heavy toxic metals lead is a brutal carcinogen that requires pitiless sensors for its capturing. The use of heterocycles for metal sensing in supramolecular chemistry is preferred due to the strong chelation they offer to toxic metals. The C1-C3 probes were synthesized and studied for their Pb2+ binding ability. All the probes were prepared by treating bromoacetyl coumarin with camphor sulphonamide, 5-dimethylamino-1-naphthalene sulphonamide, and methyl-2-amino-sulphonyl benzoate at room temperature. The probes show selective binding with Pb2+ ions in aqueous acetonitrile among different tested metal ions viz., Cu2+ , Zn2+ , Ni2+ , Mn2+, and Pb2+ ions as shown in ultraviolet (UV)-visible, nuclear magnetic resonance (NMR), and high-performance liquid chromatography (HPLC) studies. These sulphur-containing probes bind very well with Pb2+ ions by offering selectivity in binding positions that capture lead ions at their minimum possible concentration.
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Affiliation(s)
- Nidhi Sharma
- Academy of Scientific and Innovative Research (AcSIR), CSIR - Central Road Research Institute, (CRRI), New Delhi, India.,Food and Nutraceutical Division, CSIR - Institute of Himalayan Bioresource Technology, Palampur, India
| | - Ashu Gulati
- Food and Nutraceutical Division, CSIR - Institute of Himalayan Bioresource Technology, Palampur, India
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9
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Yadav M, Soni R, Chauhan MK, Sandal N. Cellular and physiological approaches to evaluate the chelating effect of Chlorella on metal ion stressed lymphocytes. Biometals 2021; 34:351-363. [PMID: 33582954 DOI: 10.1007/s10534-021-00285-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 01/01/2021] [Indexed: 10/22/2022]
Abstract
Chlorella is a green alga consumed as dietary food supplement in pulverized form. In addition to its high nutritional value, it is reported as an excellent detoxifying agent. The pulverized Chlorella is partially soluble in water and insoluble portion has been reported for removal of mercury, cadmium and radioactive strontium from body. Chlorella contains a variety of metal-binding functional groups such as carboxyl, amino, phosphoryl, hydroxyl and carbonyl groups, which has high affinity towards various metal ions. The present study was envisaged to evaluate the chelating effect of water soluble fraction of Chlorella powder (AqCH) on metal ions. Fura-2 fluorescence ratio (F340/F380) was measured by fluorescence spectrometer (FS) after the exposure of chloride salt of metals viz., strontium, cobalt, barium, cesium, thallium and mercury to lymphocytes. Pretreatment of AqCH (0.1-20 mg mL-1) was given to evaluate the attenuating effect on fura-2 fluorescence ratio induced by metal ions. The intracellular levels of these metal ions were analyzed by atomic absorption spectrophotometer (AAS) and fluorescence microscopy (FM). Pretreatment with AqCH significantly attenuated the metal induced fluorescence ratio in dose-dependent manner. The results of AAS and FM were found in coherence with fura-2 fluorescence ratio which emphasized that AqCH significantly prevented the metal ions internalization. The present study suggests AqCH chelates with these metal ions and prevents its interaction with cells thereby reducing the intracellular mobilization of Ca2+.
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Affiliation(s)
- Mahendra Yadav
- Division of CBRN Defence, Institute of Nuclear Medicine and Allied Sciences (INMAS), Defence Research and Development Organization, Brig. S.K. Mazumdar Road, Timarpur, New Delhi, 110054, India
| | - Ravi Soni
- Division of Natural Radiation Response Mechanisms, Institute of Nuclear Medicine and Allied Sciences, Defence Research and Development Organization, New Delhi, India
| | - Meenakshi Kanwar Chauhan
- Department of Pharmaceutics, Delhi Institute of Pharmaceutical Sciences and Research, New Delhi, India
| | - Nidhi Sandal
- Division of CBRN Defence, Institute of Nuclear Medicine and Allied Sciences (INMAS), Defence Research and Development Organization, Brig. S.K. Mazumdar Road, Timarpur, New Delhi, 110054, India.
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10
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Cognitive Impairment Induced by Lead Exposure during Lifespan: Mechanisms of Lead Neurotoxicity. TOXICS 2021; 9:toxics9020023. [PMID: 33525464 PMCID: PMC7912619 DOI: 10.3390/toxics9020023] [Citation(s) in RCA: 72] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/19/2021] [Accepted: 01/25/2021] [Indexed: 12/25/2022]
Abstract
Lead (Pb) is considered a strong environmental toxin with human health repercussions. Due to its widespread use and the number of people potentially exposed to different sources of this heavy metal, Pb intoxication is recognized as a public health problem in many countries. Exposure to Pb can occur through ingestion, inhalation, dermal, and transplacental routes. The magnitude of its effects depends on several toxicity conditions: lead speciation, doses, time, and age of exposure, among others. It has been demonstrated that Pb exposure induces stronger effects during early life. The central nervous system is especially vulnerable to Pb toxicity; Pb exposure is linked to cognitive impairment, executive function alterations, abnormal social behavior, and fine motor control perturbations. This review aims to provide a general view of the cognitive consequences associated with Pb exposure during early life as well as during adulthood. Additionally, it describes the neurotoxic mechanisms associated with cognitive impairment induced by Pb, which include neurochemical, molecular, and morphological changes that jointly could have a synergic effect on the cognitive performance.
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11
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Katti S, Igumenova TI. Interference of pH buffer with Pb 2+-peripheral domain interactions: obstacle or opportunity? Metallomics 2020; 12:164-172. [PMID: 32051983 DOI: 10.1039/d0mt00002g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Pb2+ is a xenobiotic metal ion that competes for Ca2+-binding sites in proteins. Using the peripheral Ca2+-sensing domains of Syt1, we show that the chelating pH buffer Bis-Tris enables identification and functional characterization of high-affinity Pb2+ sites that are likely to be targeted by bioavailable Pb2+.
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Affiliation(s)
- Sachin Katti
- Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Boulevard, College Station, TX 77843, USA.
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12
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Zou RX, Gu X, Ding JJ, Wang T, Bi N, Niu K, Ge M, Chen XT, Wang HL. Pb exposure induces an imbalance of excitatory and inhibitory synaptic transmission in cultured rat hippocampal neurons. Toxicol In Vitro 2019; 63:104742. [PMID: 31785328 DOI: 10.1016/j.tiv.2019.104742] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 11/12/2019] [Accepted: 11/24/2019] [Indexed: 12/16/2022]
Abstract
An appropriate balance of excitatory and inhibitory synapse maintains the network stability of the central nervous system. Our recent work showed lead (Pb) exposure can inhibit synaptic transmission in cultured hippocampal neurons. However, it is not clear whether Pb exposure disrupt the balance of excitatory and inhibitory synaptic transmission. Here, primary cultured hippocampal neurons from Sprague-Dawley (SD) rats were exposed to Pb (0.2 μM, 1 μM, 5 μM, respectively) from Days in Vitro (DIV) 7 to DIV 12 for 5 days and the excitatory and inhibitory synaptic transmission was examined. Patch clamp recording results showed that distinct from exposures of 0.2 μM and 5 μM, 1 μM Pb exposure significantly increased the mIPSC frequency and decreased the mEPSC frequency, leading to a uniform inhibitory outcome. Further, the number of inhibitory presynaptic puncta was significantly increased after 1 μM Pb exposure, while the number of excitatory presynaptic terminals was decreased. In addition 1 μM Pb increased the glutamic acid decarboxylase (GAD65) expression and the surface GABAA receptor (GABAAR) clusters. This shift might potentiate the synthesis of GABA and enhance the surface distribution of postsynaptic GABAAR clusters in hippocampus neurons. Together, these data showed that Pb exposure disrupted the balance of excitatory and inhibitory synaptic transmission via abnormal GABAergic neurotransmission.
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Affiliation(s)
- Rong-Xin Zou
- Engineering Research Center of Bio-process, Ministry of Education, Hefei University of Technology, 193 Tunxi Road, Hefei, Anhui 230009, PR China; School of Food Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, PR China
| | - Xiaozhen Gu
- School of Food Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, PR China
| | - Jin-Jun Ding
- School of Food Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, PR China
| | - Tiandong Wang
- School of Food Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, PR China
| | - Nanxi Bi
- School of Food Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, PR China
| | - Kang Niu
- School of Food Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, PR China
| | - Mengmeng Ge
- School of Food Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, PR China
| | - Xiang-Tao Chen
- School of Pharmacy, Anhui Medical University, Hefei, Anhui 230031, PR China.
| | - Hui-Li Wang
- Engineering Research Center of Bio-process, Ministry of Education, Hefei University of Technology, 193 Tunxi Road, Hefei, Anhui 230009, PR China; School of Food Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, PR China.
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13
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Reis CF, de Souza ID, Morais DAA, Oliveira RAC, Imparato DO, de Almeida RMC, Dalmolin RJS. Systems Biology-Based Analysis Indicates Global Transcriptional Impairment in Lead-Treated Human Neural Progenitor Cells. Front Genet 2019; 10:791. [PMID: 31552095 PMCID: PMC6748217 DOI: 10.3389/fgene.2019.00791] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 07/26/2019] [Indexed: 01/19/2023] Open
Abstract
Lead poisoning effects are wide and include nervous system impairment, peculiarly during development, leading to neural damage. Lead interaction with calcium and zinc-containing metalloproteins broadly affects cellular metabolism since these proteins are related to intracellular ion balance, activation of signaling transduction cascades, and gene expression regulation. In spite of lead being recognized as a neurotoxin, there are gaps in knowledge about the global effect of lead in modulating the transcription of entire cellular systems in neural cells. In order to investigate the effects of lead poisoning in a systemic perspective, we applied the transcriptogram methodology in an RNA-seq dataset of human embryonic-derived neural progenitor cells (ES-NP cells) treated with 30 µM lead acetate for 26 days. We observed early downregulation of several cellular systems involved with cell differentiation, such as cytoskeleton organization, RNA, and protein biosynthesis. The downregulated cellular systems presented big and tightly connected networks. For long treatment times (12 to 26 days), it was possible to observe a massive impairment in cell transcription profile. Taking the enriched terms together, we observed interference in all layers of gene expression regulation, from chromatin remodeling to vesicle transport. Considering that ES-NP cells are progenitor cells that can originate other neural cell types, our results suggest that lead-induced gene expression disturbance might impair cells’ ability to differentiate, therefore influencing ES-NP cells’ fate.
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Affiliation(s)
- Clovis F Reis
- Bioinformatics Multidisciplinary Environment - IMD, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Iara D de Souza
- Bioinformatics Multidisciplinary Environment - IMD, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Diego A A Morais
- Bioinformatics Multidisciplinary Environment - IMD, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Raffael A C Oliveira
- Bioinformatics Multidisciplinary Environment - IMD, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Danilo O Imparato
- Bioinformatics Multidisciplinary Environment - IMD, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Rita M C de Almeida
- Institute of Physics and National Institute of Science and Technology: Complex Systems, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Rodrigo J S Dalmolin
- Bioinformatics Multidisciplinary Environment - IMD, Federal University of Rio Grande do Norte, Natal, Brazil.,Department of Biochemistry - CB, Federal University of Rio Grande do Norte, Natal, Brazil
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14
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Fluorescence Characteristics of Aqueous Synthesized Tin Oxide Quantum Dots for the Detection of Heavy Metal Ions in Contaminated Water. NANOMATERIALS 2019; 9:nano9091294. [PMID: 31510076 PMCID: PMC6781020 DOI: 10.3390/nano9091294] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 09/05/2019] [Accepted: 09/06/2019] [Indexed: 01/20/2023]
Abstract
Tin oxide quantum dots were synthesized in aqueous solution via a simple hydrolysis and oxidation process. The morphology observation showed that the quantum dots had an average grain size of 2.23 nm. The rutile phase SnO2 was confirmed by the structural and compositional characterization. The fluorescence spectroscopy of quantum dots was used to detect the heavy metal ions of Cd2+, Fe3+, Ni2+ and Pb2+, which caused the quenching effect of photoluminescence. The quantum dots showed the response of 2.48 to 100 ppm Ni2+. The prepared SnO2 quantum dots exhibited prospective in the detection of heavy metal ions in contaminated water, including deionized water, deionized water with Fe3+, reclaimed water and sea water. The limit of detection was as low as 0.01 ppm for Ni2+ detection. The first principle calculation based on the density function theory demonstrated the dependence of fluorescence response on the adsorption energy of heavy metal ions as well as ion radius. The mechanism of fluorescence response was discussed based on the interaction between Sn vacancies and Ni2+ ions. A linear correlation of fluorescence emission intensity against Ni2+ concentration was obtained in the logarithmic coordinates. The density of active Sn vacancies was the crucial factor that determined fluorescence response of SnO2 QDs to heavy metal ions.
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15
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Rocha A, Trujillo KA. Neurotoxicity of low-level lead exposure: History, mechanisms of action, and behavioral effects in humans and preclinical models. Neurotoxicology 2019; 73:58-80. [PMID: 30836127 PMCID: PMC7462347 DOI: 10.1016/j.neuro.2019.02.021] [Citation(s) in RCA: 101] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 02/26/2019] [Accepted: 02/27/2019] [Indexed: 12/20/2022]
Abstract
Lead is a neurotoxin that produces long-term, perhaps irreversible, effects on health and well-being. This article summarizes clinical and preclinical studies that have employed a variety of research techniques to examine the neurotoxic effects of low levels of lead exposure. A historical perspective is presented, followed by an overview of studies that examined behavioral and cognitive outcomes. In addition, a short summary of potential mechanisms of action is provided with a focus on calcium-dependent processes. The current level of concern, or reference level, set by the CDC is 5 μg/dL of lead in blood and a revision to 3.5 μg/dL has been suggested. However, levels of lead below 3 μg/dL have been shown to produce diminished cognitive function and maladaptive behavior in humans and animal models. Because much of the research has focused on higher concentrations of lead, work on low concentrations is needed to better understand the neurobehavioral effects and mechanisms of action of this neurotoxic metal.
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MESH Headings
- Adolescent
- Adolescent Behavior/drug effects
- Adolescent Development/drug effects
- Adult
- Age Factors
- Aged
- Animals
- Brain/drug effects
- Brain/growth & development
- Child
- Child Behavior/drug effects
- Child Development/drug effects
- Child, Preschool
- Cognition/drug effects
- Dose-Response Relationship, Drug
- History, 20th Century
- History, 21st Century
- Humans
- Lead Poisoning, Nervous System, Adult/history
- Lead Poisoning, Nervous System, Adult/physiopathology
- Lead Poisoning, Nervous System, Adult/psychology
- Lead Poisoning, Nervous System, Childhood/history
- Lead Poisoning, Nervous System, Childhood/physiopathology
- Lead Poisoning, Nervous System, Childhood/psychology
- Mice
- Middle Aged
- Rats
- Risk Assessment
- Risk Factors
- Toxicity Tests
- Young Adult
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Affiliation(s)
- Angelica Rocha
- California State University San Marcos, San Marcos, CA 92069, USA.
| | - Keith A Trujillo
- California State University San Marcos, San Marcos, CA 92069, USA
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16
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Yun S, Wu Y, Niu R, Feng C, Wang J. Effects of lead exposure on brain glucose metabolism and insulin signaling pathway in the hippocampus of rats. Toxicol Lett 2019; 310:23-30. [PMID: 30980912 DOI: 10.1016/j.toxlet.2019.04.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Revised: 03/07/2019] [Accepted: 04/08/2019] [Indexed: 12/21/2022]
Abstract
The aim of this study was to determine whether Pb affects glucose metabolism in the hippocampus of rats. Male Sprague-Dawley rats aged 21 days were orally administered a 0.1%, 0.2%, or 0.3% lead acetate solution in deionized water for 65 days. Then, the weight of the rats; brain Pb content; brain glucose levels; activities of hexokinase, fructose-6-phosphate kinase, pyruvate kinase, glucose-6-phosphate dehydrogenase; expression of genes related to the insulin signaling pathway; as well as the gene and protein expression of glucose transporter (GLUT)-1 and GLUT-3 in the hippocampus were evaluated. The results showed that Pb content in the brain tissue of rats in the dose groups significantly increased, whereas the body weight gain, activities of glucose metabolism-related enzymes, and expression of the insulin signaling pathway-related genes significantly decreased compared to the corresponding values in the control group. In comparison with the control group, the brain glucose levels increased significantly in the low-dose group, but there were no significant differences with the middle- and high-dose groups. Furthermore, the mRNA of GLUT-1 in the three dose groups and the GLUT-3 in the middle- and high-dose groups rose markedly, while the GLUT-1 and GLUT-3 protein expression significantly increased in the middle- and high-dose groups and in the high-dose group, respectively. Taken together, the results showed that Pb exposure resulted in a lower body weight gain, higher brain Pb content and also affected brain glucose metabolism and the insulin signaling pathway.
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Affiliation(s)
- Shaojun Yun
- College of Food Science and Engineering, Shanxi Agricultural University, Taigu, 030801, China; Shanxi Key Laboratory of Ecological Animal Science and Environmental Medicine, Shanxi Agricultural University, Taigu, 030801, China
| | - Yanli Wu
- College of Food Science and Engineering, Shanxi Agricultural University, Taigu, 030801, China
| | - Ruiyan Niu
- Shanxi Key Laboratory of Ecological Animal Science and Environmental Medicine, Shanxi Agricultural University, Taigu, 030801, China
| | - Cuiping Feng
- College of Food Science and Engineering, Shanxi Agricultural University, Taigu, 030801, China.
| | - Jundong Wang
- Shanxi Key Laboratory of Ecological Animal Science and Environmental Medicine, Shanxi Agricultural University, Taigu, 030801, China.
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17
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Cole TR, Erickson SG, Morales KA, Sung M, Holzenburg A, Igumenova TI. Cd(II)- and Pb(II)-Induced Self-Assembly of Peripheral Membrane Domains from Protein Kinase C. Biochemistry 2019; 58:509-513. [PMID: 30584764 DOI: 10.1021/acs.biochem.8b01235] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cd2+ and Pb2+ are xenobiotic heavy metal ions that use ionic mimicry to interfere with the cellular function of biomacromolecules. Using a combination of SAXS, electron microscopy, FRET, and solution NMR spectroscopy, we demonstrate that treatment with Cd2+ and Pb2+ causes self-assembly of protein kinase C regulatory domains that peripherally associate with membranes. The self-assembly process successfully competes with ionic mimicry and is mediated by conserved protein regions that are distinct from the canonical Ca2+-binding motifs of protein kinase C. The ability of protein oligomers to interact with anionic membranes is enhanced compared to the monomeric species. Our findings suggest that metal-ion-dependent peripheral membrane domains can be utilized for generating protein-metal-ion nanoclusters and serve as biotemplates for the design of sequestration agents.
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Affiliation(s)
- Taylor R Cole
- Department of Biochemistry and Biophysics , Texas A&M University , 300 Olsen Boulevard , College Station , Texas 77843 , United States
| | - Samuel G Erickson
- Department of Biochemistry and Biophysics , Texas A&M University , 300 Olsen Boulevard , College Station , Texas 77843 , United States
| | - Krystal A Morales
- Department of Biochemistry and Biophysics , Texas A&M University , 300 Olsen Boulevard , College Station , Texas 77843 , United States
| | - MinWoo Sung
- Department of Biology , Texas A&M University , College Station , Texas 77843 , United States
| | - Andreas Holzenburg
- School of Medicine , University of Texas Rio Grande Valley , Harlingen , Texas 78550 , United States
| | - Tatyana I Igumenova
- Department of Biochemistry and Biophysics , Texas A&M University , 300 Olsen Boulevard , College Station , Texas 77843 , United States
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18
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Dudev T, Grauffel C, Lim C. How Pb2+ Binds and Modulates Properties of Ca2+-Signaling Proteins. Inorg Chem 2018; 57:14798-14809. [DOI: 10.1021/acs.inorgchem.8b02548] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Todor Dudev
- Faculty of Chemistry and Pharmacy, Sofia University, Sofia 1164, Bulgaria
| | - Cédric Grauffel
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Carmay Lim
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
- Department of Chemistry, National Tsing Hua University, Hsinchu 300, Taiwan
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19
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Katti S, Her B, Srivastava AK, Taylor AB, Lockless SW, Igumenova TI. High affinity interactions of Pb 2+ with synaptotagmin I. Metallomics 2018; 10:1211-1222. [PMID: 30063057 DOI: 10.1039/c8mt00135a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Lead (Pb) is a potent neurotoxin that disrupts synaptic neurotransmission. We report that Synaptotagmin I (SytI), a key regulator of Ca2+-evoked neurotransmitter release, has two high-affinity Pb2+ binding sites that belong to its cytosolic C2A and C2B domains. The crystal structures of Pb2+-complexed C2 domains revealed that protein-bound Pb2+ ions have holodirected coordination geometries and all-oxygen coordination spheres. The on-rate constants of Pb2+ binding to the C2 domains of SytI are comparable to those of Ca2+ and are diffusion-limited. In contrast, the off-rate constants are at least two orders of magnitude smaller, indicating that Pb2+ can serve as both a thermodynamic and kinetic trap for the C2 domains. We demonstrate, using NMR spectroscopy, that population of these sites by Pb2+ ions inhibits further Ca2+ binding despite the existing coordination vacancies. Our work offers a unique insight into the bioinorganic chemistry of Pb(ii) and suggests a mechanism by which low concentrations of Pb2+ ions can interfere with the Ca2+-dependent function of SytI in the cell.
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Affiliation(s)
- Sachin Katti
- Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Boulevard, College Station, TX 77843, USA.
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20
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Shaily, Kumar A, Parveen I, Ahmed N. Highly selective and sensitive coumarin-triazole-based fluorometric 'turn-off' sensor for detection of Pb 2+ ions. LUMINESCENCE 2018; 33:713-721. [PMID: 29498808 DOI: 10.1002/bio.3468] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 12/10/2017] [Accepted: 01/18/2018] [Indexed: 01/29/2023]
Abstract
Exposure to even very low concentrations of Pb2+ is known to cause cardiovascular, neurological, developmental, and reproductive disorders, and affects children in particular more severely. Consequently, much effort has been dedicated to the development of colorimetric and fluorescent sensors that can selectively detect Pb2+ ions. Here, we describe the development of a triazole-based fluorescent sensor L5 for Pb2+ ion detection. The fluorescence intensity of chemosensor L5 was selectively quenched by Pb2+ ions and a clear color change from colorless to yellow could be observed by the naked eye. Chemosensor L5 exhibited high sensitivity and selectivity towards Pb2+ ions in phosphate-buffered solution [20 mM, 1:9 DMSO/H2 O (v/v), pH 8.0] with a 1:1 binding stoichiometry, a detection limit of 1.9 nM and a 6.76 × 106 M-1 binding constant. Additionally, low-cost and easy-to-prepare test strips impregnated with chemosensor L5 were also produced for efficient of Pb2+ detection and proved the practical use of this test.
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Affiliation(s)
- Shaily
- Department of Chemistry, Indian Institute of Technology, Roorkee, India.,Department of Chemistry, D.B.S. (P.G.) College Dehradun, India
| | - Ajay Kumar
- Department of Chemistry, D.B.S. (P.G.) College Dehradun, India
| | - Iram Parveen
- Department of Chemistry, Indian Institute of Technology, Roorkee, India
| | - Naseem Ahmed
- Department of Chemistry, Indian Institute of Technology, Roorkee, India
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21
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de Souza ID, de Andrade AS, Dalmolin RJS. Lead-interacting proteins and their implication in lead poisoning. Crit Rev Toxicol 2018; 48:375-386. [DOI: 10.1080/10408444.2018.1429387] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Iara Dantas de Souza
- Bioinformatics Multidisciplinary Environment – IMD, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Abraão Silveira de Andrade
- Bioinformatics Multidisciplinary Environment – IMD, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Rodrigo Juliani Siqueira Dalmolin
- Bioinformatics Multidisciplinary Environment – IMD, Federal University of Rio Grande do Norte, Natal, Brazil
- Department of Biochemistry – CB, Federal University of Rio Grande do Norte, Natal, Brazil
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22
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Gorkhali R, Huang K, Kirberger M, Yang JJ. Defining potential roles of Pb(2+) in neurotoxicity from a calciomics approach. Metallomics 2017; 8:563-78. [PMID: 27108875 DOI: 10.1039/c6mt00038j] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Metal ions play crucial roles in numerous biological processes, facilitating biochemical reactions by binding to various proteins. An increasing body of evidence suggests that neurotoxicity associated with exposure to nonessential metals (e.g., Pb(2+)) involves disruption of synaptic activity, and these observed effects are associated with the ability of Pb(2+) to interfere with Zn(2+) and Ca(2+)-dependent functions. However, the molecular mechanism behind Pb(2+) toxicity remains a topic of debate. In this review, we first discuss potential neuronal Ca(2+) binding protein (CaBP) targets for Pb(2+) such as calmodulin (CaM), synaptotagmin, neuronal calcium sensor-1 (NCS-1), N-methyl-d-aspartate receptor (NMDAR) and family C of G-protein coupled receptors (cGPCRs), and their involvement in Ca(2+)-signalling pathways. We then compare metal binding properties between Ca(2+) and Pb(2+) to understand the structural implications of Pb(2+) binding to CaBPs. Statistical and biophysical studies (e.g., NMR and fluorescence spectroscopy) of Pb(2+) binding are discussed to investigate the molecular mechanism behind Pb(2+) toxicity. These studies identify an opportunistic, allosteric binding of Pb(2+) to CaM, which is distinct from ionic displacement. Together, these data suggest three potential modes of Pb(2+) activity related to molecular and/or neural toxicity: (i) Pb(2+) can occupy Ca(2+)-binding sites, inhibiting the activity of the protein by structural modulation, (ii) Pb(2+) can mimic Ca(2+) in the binding sites, falsely activating the protein and perturbing downstream activities, or (iii) Pb(2+) can bind outside of the Ca(2+)-binding sites, resulting in the allosteric modulation of the protein activity. Moreover, the data further suggest that even low concentrations of Pb(2+) can interfere at multiple points within the neuronal Ca(2+) signalling pathways to cause neurotoxicity.
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Affiliation(s)
- Rakshya Gorkhali
- Department of Chemistry, Center for Diagnostics and Therapeutics, and Drug Design and Biotechnology, Georgia State University, Atlanta, GA 3030, USA.
| | - Kenneth Huang
- Department of Chemistry, Center for Diagnostics and Therapeutics, and Drug Design and Biotechnology, Georgia State University, Atlanta, GA 3030, USA.
| | - Michael Kirberger
- Department of Chemistry and Physics, Clayton State University, Morrow, GA 30260, USA.
| | - Jenny J Yang
- Department of Chemistry, Center for Diagnostics and Therapeutics, and Drug Design and Biotechnology, Georgia State University, Atlanta, GA 3030, USA.
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23
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Kalia V, Perera F, Tang D. Environmental Pollutants and Neurodevelopment: Review of Benefits From Closure of a Coal-Burning Power Plant in Tongliang, China. Glob Pediatr Health 2017; 4:2333794X17721609. [PMID: 28812058 PMCID: PMC5542072 DOI: 10.1177/2333794x17721609] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 06/13/2017] [Accepted: 06/21/2017] [Indexed: 12/02/2022] Open
Abstract
Background. Understanding preventable causes of neurodevelopmental disorders is a public health priority. Polycyclic aromatic hydrocarbons (PAH) from combustion of fossil fuel, lead, and mercury are among known neurodevelopmental toxicants. Method. For the first time, we comprehensively review the findings from a study by the Columbia Center for Children's Environmental Health and Chinese partners that followed 2 groups of mother-child pairs, one from 2002 and another from 2005, in Tongliang County, China. Pregnant mothers in the 2 cohorts experienced different exposure to PAH because a local coal-burning power plant was shut down in 2004. Investigators assessed change in prenatal PAH exposure, measured using a biomarker (benzo[a]pyrene [BaP]-DNA adducts in cord blood). Developmental quotients were measured using the Gesell Developmental Scales at age 2 and IQ was assessed using the Wechsler Intelligence Scale for Children at age 5. Biologic markers of preclinical response were measured in cord blood: methylation status of long interspersed nuclear elements (LINE1), an indicator of genomic stability, and brain-derived neurotrophic factor (BDNF), a neuronal growth promoter. Analyses accounted for co-exposure to lead and mercury. Results. BaP-DNA adducts were significantly inversely associated with Gesell Developmental Scales scores in the first cohort but not in the second cohort; and levels of BDNF and LINE1 methylation were higher in the second cohort. Conclusion. In this study, reduced exposure to PAH was associated with beneficial effects on neurodevelopment as well as molecular changes related to improved brain development and health. These benefits should encourage further efforts to limit exposure to these toxic pollutants.
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Affiliation(s)
- Vrinda Kalia
- Department of Environmental Health Sciences, Columbia Center for Children’s Environemental Health, Mailman School of Public Health, Columbia University, New York, NY, USA
| | - Frederica Perera
- Department of Environmental Health Sciences, Columbia Center for Children’s Environemental Health, Mailman School of Public Health, Columbia University, New York, NY, USA
| | - Deliang Tang
- Department of Environmental Health Sciences, Columbia Center for Children’s Environemental Health, Mailman School of Public Health, Columbia University, New York, NY, USA
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24
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Yu H, Li T, Cui Y, Liao Y, Wang G, Gao L, Zhao F, Jin Y. Effects of lead exposure on d-serine metabolism in the hippocampus of mice at the early developmental stages. Toxicology 2014; 325:189-99. [DOI: 10.1016/j.tox.2014.09.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 09/15/2014] [Accepted: 09/16/2014] [Indexed: 02/05/2023]
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25
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Kirberger M, Wong HC, Jiang J, Yang JJ. Metal toxicity and opportunistic binding of Pb(2+) in proteins. J Inorg Biochem 2013; 125:40-9. [PMID: 23692958 DOI: 10.1016/j.jinorgbio.2013.04.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Revised: 04/09/2013] [Accepted: 04/11/2013] [Indexed: 10/26/2022]
Abstract
Lead toxicity is associated with various human diseases. While Ca(2+) binding proteins such as calmodulin (CaM) are often reported to be molecular targets for Pb(2+)-binding and lead toxicity, the effect of Pb(2+) on the Ca(2+)/CaM regulated biological activities cannot be described by the primary mechanism of ionic displacement (e.g., ionic mimicry). The focus of this study was to investigate the mechanism of lead toxicity through binding differences between Ca(2+) and Pb(2+) for CaM, an essential intracellular trigger protein with two EF-Hand Ca(2+)-binding sites in each of its two domains that regulates many molecular targets via Ca(2+)-induced conformational change. Fluorescence changes in phenylalanine indicated that Pb(2+) binds with 8-fold higher affinity than Ca(2+) in the N-terminal domain. Additionally, NMR chemical shift changes and an unusual biphasic response observed in tyrosine fluorescence associated with C-terminal domain sites EF-III and EF-IV suggest a single higher affinity Pb(2+)-binding site with a 3-fold higher affinity than Ca(2+), coupled with a second site exhibiting affinity nearly equivalent to that of the N-terminal domain sites. Our results further indicate that Pb(2+) displaces Ca(2+) only in the N-terminal domain, with minimal perturbation of the C-terminal domain, however significant structural/dynamic changes are observed in the trans-domain linker region which appear to be due to Pb(2+)-binding outside of the known calcium-binding sites. These data suggest that opportunistic Pb(2+)-binding in Ca(2+)/CaM has a profound impact on the conformation and dynamics of the essential molecular recognition sites of the central helix, and provides insight into the molecular toxicity of non-essential metal ions.
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Affiliation(s)
- Michael Kirberger
- Department of Chemistry, Center for Diagnostics and Therapeutics and Drug Design and Biotechnology, Georgia State University, Atlanta, GA, 30303, United States
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26
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Deibler K, Basu P. Continuing issues with Lead: Recent Advances in Detection. Eur J Inorg Chem 2013; 2013:1086-1096. [PMID: 25089117 PMCID: PMC4116340 DOI: 10.1002/ejic.201200997] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Indexed: 01/13/2023]
Abstract
In the past Pb2+ has been used in many industries, including gasoline, piping, toys, paints, and more. The use of lead has led to a natural increase of lead concentration in the environment especially in air and water. According to the U.S. CDC "no level of lead in blood is considered safe." Exposure to very low amounts of lead can cause several health complications including developmental and neurological disorders. Over the past several years an emphasis has been placed in developing systems that can detect lead at a very low concentration. A great deal of work has been accomplished in the development of Pb2+ sensors that can not only detect but also quantify the amount and in some cases in the presence of other metal ions. Herein, we describe current regulations, mode of exposure and recent development of sensing techniques.
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Affiliation(s)
- Kristine Deibler
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Ave., Pittsburgh, PA 15282 (USA), Fax: (+1) 412-396-5683
| | - Partha Basu
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Ave., Pittsburgh, PA 15282 (USA), Fax: (+1) 412-396-5683
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27
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Role of calcium channels in heavy metal toxicity. ISRN TOXICOLOGY 2013; 2013:184360. [PMID: 23724297 PMCID: PMC3658387 DOI: 10.1155/2013/184360] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 12/23/2012] [Indexed: 01/01/2023]
Abstract
The role of voltage-dependent Ca channels (VDCC) in the membrane permeation of two toxic metals, lead (Pb) and cadmium (Cd), was studied in mammalian cells. Both metals interact with Ca-binding sites, but, while Cd influx appears to occur mainly through the same pathways as Ca, Pb is also rapidly taken up by different passive transport systems. Furthermore, I compared the effect of Cd in two Chinese hamster ovary (CHO) cell lines, a wild-type and a modified cell line, which were permanently transfected with an L-type VDCC. When cultures were subjected to a brief (30–60 min) exposure to 50–100 μM Cd, apoptotic features, metal accumulation, and death were comparable in both cell lines although, in transfected cells, the effect of Cd treatment was partially prevented by nimodipine (VDCC antagonist) and enhanced by BayK8644 (VDCC agonist). Thus, expression of L-type Ca channels is not sufficient to modify Cd accumulation and sensitivity to a toxicological significant extent and while both Cd and Pb can take advantage of VDCC to permeate the membrane, these transport proteins are not the only, and frequently not the most important, pathways of permeation.
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28
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Charlet L, Chapron Y, Faller P, Kirsch R, Stone AT, Baveye PC. Neurodegenerative diseases and exposure to the environmental metals Mn, Pb, and Hg. Coord Chem Rev 2012. [DOI: 10.1016/j.ccr.2012.05.012] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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29
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Morales KA, Igumenova TI. Synergistic effect of Pb(2+) and phosphatidylinositol 4,5-bisphosphate on C2 domain-membrane interactions. Biochemistry 2012; 51:3349-60. [PMID: 22475207 DOI: 10.1021/bi201850h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ca(2+)-responsive C2 domains are peripheral membrane modules that target their host proteins to anionic membranes upon binding Ca(2+) ions. Several C2 domain-containing proteins, such as protein kinase C isoenzymes (PKCs), have been identified as molecular targets of Pb(2+), a known environmental toxin. We demonstrated previously that the C2 domain from PKCα (C2α) binds Pb(2+) with high affinity and undergoes membrane insertion in the Pb(2+)-complexed form. The objective of this work was to determine the effect of phosphatidylinositol 4,5-bisphosphate (PIP(2)) on the C2α-Pb(2+) interactions. Using nuclear magnetic resonance (NMR) experiments, we show that Pb(2+) and PIP(2) synergistically enhance each other's affinity for C2α. Moreover, the affinity of C2α for PIP(2) increases upon progressive saturation of the metal-binding sites. Combining the NMR data with the results of protein-to-membrane Förster resonance energy transfer and vesicle sedimentation experiments, we demonstrate that PIP(2) can influence two aspects of C2α-Pb(2+)-membrane interactions: the affinity of C2α for Pb(2+) and the association of Pb(2+) with the anionic sites on the membrane. Both factors may contribute to the toxic effect of Pb(2+) resulting from the aberrant modulation of PKCα activity. Finally, we propose a mechanism for Pb(2+) outcompeting Ca(2+) from membrane-bound C2α.
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Affiliation(s)
- Krystal A Morales
- Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Boulevard, College Station, TX 77843-2128, USA
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30
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Sadiq S, Ghazala Z, Chowdhury A, Büsselberg D. Metal toxicity at the synapse: presynaptic, postsynaptic, and long-term effects. J Toxicol 2012; 2012:132671. [PMID: 22287959 PMCID: PMC3263637 DOI: 10.1155/2012/132671] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 07/05/2011] [Indexed: 12/19/2022] Open
Abstract
Metal neurotoxicity is a global health concern. This paper summarizes the evidence for metal interactions with synaptic transmission and synaptic plasticity. Presynaptically metal ions modulate neurotransmitter release through their interaction with synaptic vesicles, ion channels, and the metabolism of neurotransmitters (NT). Many metals (e.g., Pb(2+), Cd(2+), and Hg(+)) also interact with intracellular signaling pathways. Postsynaptically, processes associated with the binding of NT to their receptors, activation of channels, and degradation of NT are altered by metals. Zn(2+), Pb(2+), Cu(2+), Cd(2+), Ni(2+), Co(2+), Li(3+), Hg(+), and methylmercury modulate NMDA, AMPA/kainate, and/or GABA receptors activity. Al(3+), Pb(2+), Cd(2+), and As(2)O(3) also impair synaptic plasticity by targeting molecules such as CaM, PKC, and NOS as well as the transcription machinery involved in the maintenance of synaptic plasticity. The multiple effects of metals might occur simultaneously and are based on the specific metal species, metal concentrations, and the types of neurons involved.
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Affiliation(s)
| | | | | | - Dietrich Büsselberg
- Weill Cornell Medical College in Qatar, Qatar Foundation—Education City, P.O. Box 24144, Doha, Qatar
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Waggas AM. Grape Seed Extract (<i>Vitisvinifera</i>) Alleviate Neurotoxicity and Hepatotoxicity Induced by Lead Acetate in Male Albino Rats. ACTA ACUST UNITED AC 2012. [DOI: 10.4236/jbbs.2012.22021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Morales KA, Lasagna M, Gribenko AV, Yoon Y, Reinhart GD, Lee JC, Cho W, Li P, Igumenova TI. Pb2+ as modulator of protein-membrane interactions. J Am Chem Soc 2011; 133:10599-611. [PMID: 21615172 DOI: 10.1021/ja2032772] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Lead is a potent environmental toxin that mimics the effects of divalent metal ions, such as zinc and calcium, in the context of specific molecular targets and signaling processes. The molecular mechanism of lead toxicity remains poorly understood. The objective of this work was to characterize the effect of Pb(2+) on the structure and membrane-binding properties of C2α. C2α is a peripheral membrane-binding domain of Protein Kinase Cα (PKCα), which is a well-documented molecular target of lead. Using NMR and isothermal titration calorimetry (ITC) techniques, we established that C2α binds Pb(2+) with higher affinity than its natural cofactor, Ca(2+). To gain insight into the coordination geometry of protein-bound Pb(2+), we determined the crystal structures of apo and Pb(2+)-bound C2α at 1.9 and 1.5 Å resolution, respectively. A comparison of these structures revealed that the metal-binding site is not preorganized and that rotation of the oxygen-donating side chains is required for the metal coordination to occur. Remarkably, we found that holodirected and hemidirected coordination geometries for the two Pb(2+) ions coexist within a single protein molecule. Using protein-to-membrane Förster resonance energy transfer (FRET) spectroscopy, we demonstrated that Pb(2+) displaces Ca(2+) from C2α in the presence of lipid membranes through the high-affinity interaction with the membrane-unbound C2α. In addition, Pb(2+) associates with phosphatidylserine-containing membranes and thereby competes with C2α for the membrane-binding sites. This process can contribute to the inhibitory effect of Pb(2+) on the PKCα activity.
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Affiliation(s)
- Krystal A Morales
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA
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Molecular neurobiology of lead (Pb(2+)): effects on synaptic function. Mol Neurobiol 2010; 42:151-60. [PMID: 21042954 DOI: 10.1007/s12035-010-8146-0] [Citation(s) in RCA: 143] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Accepted: 10/13/2010] [Indexed: 12/16/2022]
Abstract
Lead (Pb(2+)) is a ubiquitous environmental neurotoxicant that continues to threaten public health on a global scale. Epidemiological studies have demonstrated detrimental effects of Pb(2+) on childhood IQ at very low levels of exposure. Recently, a mechanistic understanding of how Pb(2+) affects brain development has begun to emerge. The cognitive effects of Pb(2+) exposure are believed to be mediated through its selective inhibition of the N-methyl-D: -aspartate receptor (NMDAR). Studies in animal models of developmental Pb(2+) exposure exhibit altered NMDAR subunit ontogeny and disruption of NMDAR-dependent intracellular signaling. Additional studies have reported that Pb(2+) exposure inhibits presynaptic calcium (Ca(2+)) channels and affects presynaptic neurotransmission, but a mechanistic link between presynaptic and postsynaptic effects has been missing. Recent work has suggested that the presynaptic and postsynaptic effects of Pb(2+) exposure are both due to inhibition of the NMDAR by Pb(2+), and that the presynaptic effects of Pb(2+) may be mediated by disruption of NMDAR activity-dependent signaling of brain-derived neurotrophic factor (BDNF). These findings provide the basis for the first working model to describe the effects of Pb(2+) exposure on synaptic function. Here, we review the neurotoxic effects of Pb(2+) exposure and discuss the known effects of Pb(2+) exposure in light of these recent findings.
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Neal AP, Stansfield KH, Worley PF, Thompson RE, Guilarte TR. Lead exposure during synaptogenesis alters vesicular proteins and impairs vesicular release: potential role of NMDA receptor-dependent BDNF signaling. Toxicol Sci 2010; 116:249-63. [PMID: 20375082 DOI: 10.1093/toxsci/kfq111] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Lead (Pb(2+)) exposure is known to affect presynaptic neurotransmitter release in both in vivo and cell culture models. However, the precise mechanism by which Pb(2+) impairs neurotransmitter release remains unknown. In the current study, we show that Pb(2+) exposure during synaptogenesis in cultured hippocampal neurons produces the loss of synaptophysin (Syn) and synaptobrevin (Syb), two proteins involved in vesicular release. Pb(2+) exposure also increased the number of presynaptic contact sites. However, many of these putative presynaptic contact sites lack Soluble NSF attachment protein receptor complex proteins involved in vesicular exocytosis. Analysis of vesicular release using FM 1-43 dye confirmed that Pb(2+) exposure impaired vesicular release and reduced the number of fast-releasing sites. Because Pb(2+) is a potent N-methyl-D-aspartate receptor (NMDAR) antagonist, we tested the hypothesis that NMDAR inhibition may be producing the presynaptic effects. We show that NMDAR inhibition by aminophosphonovaleric acid mimics the presynaptic effects of Pb(2+) exposure. NMDAR activity has been linked to the signaling of the transsynaptic neurotrophin brain-derived neurotrophic factor (BDNF), and we observed that both the cellular expression of proBDNF and release of BDNF were decreased during the same period of Pb(2+) exposure. Furthermore, exogenous addition of BDNF rescued the presynaptic effects of Pb(2+). We suggest that the presynaptic deficits resulting from Pb(2+) exposure during synaptogenesis are mediated by disruption of NMDAR-dependent BDNF signaling.
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Affiliation(s)
- April P Neal
- Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, USA
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Counter SA, Buchanan LH, Ortega F. Neurophysiologic and neurocognitive case profiles of Andean patients with chronic environmental lead poisoning. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2009; 72:1150-1159. [PMID: 20077183 DOI: 10.1080/15287390903091772] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This report presents case profiles of three siblings in a family of lead (Pb) glazing workers living in a Pb-contaminated Andean village who presented with extreme plumbism (blood Pb levels: 47 to 128 microg/dl) from childhood to adolescence. These cases are examples of persons who have chronic Pb poisoning as a result of prolonged occupational and environmental exposure in a Pb-glazing ceramic cottage industry in the study area. Using behavioral and physiological techniques for measuring the integrity of the peripheral and central auditory systems, including otoacoustic emissions, and replicated auditory brainstem electrophysiological potentials, the authors found normal auditory neurosensory function in each patient, thus ruling out hearing impairment as a basis for adverse neurocognitive outcomes. This finding is contrary to the prevailing view regarding the detrimental effects of Pb poisoning on the cochlear and auditory brainstem of children. Performance on tests of visual spatial intelligence and auditory memory/attention was below average in these patients, which may underlie their reported learning disabilities. In two of the cases, there was an improvement in cognitive performance following a lowering of PbB levels from chelation therapy and Pb prevention education, suggesting some level of reversibility of their neurocognitive deficits. Nevertheless, these case profiles suggest that if the patients persist in Pb-glazing activities, in spite of repeated chelation therapy and family counseling, they may continue to be re-intoxicated and remain at risk for learning disabilities and other neurological impairments.
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Affiliation(s)
- S Allen Counter
- Department of Neurology, Harvard Medical School/The Biological Laboratories, Cambridge, Massachusetts, USA.
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Counter SA, Buchanan LH, Ortega F. Neurocognitive screening of lead-exposed andean adolescents and young adults. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2009; 72:625-632. [PMID: 19308847 DOI: 10.1080/15287390902769410] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
This study was designed to assess the utility of two psychometric tests with putative minimal cultural bias for use in field screening of lead (Pb)-exposed Ecuadorian Andean workers. Specifically, the study evaluated the effectiveness in Pb-exposed adolescents and young adults of a nonverbal reasoning test standardized for younger children, and compared the findings with performance on a test of auditory memory. The Raven Coloured Progressive Matrices (RCPM) was used as a test of nonverbal intelligence, and the Digit Span subtest of the Wechsler IV intelligence scale was used to assess auditory memory/attention. The participants were 35 chronically Pb-exposed Pb-glazing workers, aged 12-21 yr. Blood lead (PbB) levels for the study group ranged from 3 to 86 microg/dl, with 65.7% of the group at and above 10 microg/dl. Zinc protoporphyrin heme ratios (ZPP/heme) ranged from 38 to 380 micromol/mol, with 57.1% of the participants showing abnormal ZPP/heme (>69 micromol/mol). ZPP/heme was significantly correlated with PbB levels, suggesting chronic Pb exposure. Performance on the RCPM was less than average on the U.S., British, and Puerto Rican norms, but average on the Peruvian norms. Significant inverse associations between PbB/ZPP concentrations and RCPM standard scores using the U.S., Puerto Rican, and Peruvian norms were observed, indicating decreasing RCPM test performance with increasing PbB and ZPP levels. RCPM scores were significantly correlated with performance on the Digit Span test for auditory memory. Mean Digit Span scale score was less than average, suggesting auditory memory/attention deficits. In conclusion, both the RCPM and Digit Span tests were found to be effective instruments for field screening of visual-spatial reasoning and auditory memory abilities, respectively, in Pb-exposed Andean adolescents and young adults.
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Affiliation(s)
- S Allen Counter
- Department of Neurology, Harvard Medical School/The Biological Laboratories, Cambridge, Massachusetts, USA.
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Kirberger M, Yang JJ. Structural differences between Pb2+- and Ca2+-binding sites in proteins: implications with respect to toxicity. J Inorg Biochem 2008; 102:1901-9. [PMID: 18684507 DOI: 10.1016/j.jinorgbio.2008.06.014] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2008] [Revised: 06/20/2008] [Accepted: 06/23/2008] [Indexed: 11/19/2022]
Abstract
Pb(2+) is known to displace physiologically-relevant metal ions in proteins. To investigate potential relationships between Pb(2+)/protein complexes and toxicity, data from the protein data bank were analyzed to compare structural properties of Pb(2+)- and Ca(2+)-binding sites. Results of this analysis reveal that the majority of Pb(2+) sites (77.1%) involve 2-5 binding ligands, compared with 6+/-2 for non-EF-Hand and 7+/-1 for EF-Hand Ca(2+)-binding sites. The mean net negative charge by site (1.7) fell between values noted for non-EF-Hand (1+/-1) and EF-Hand (3+/-1). Oxygen is the dominant ligand for both Pb(2+) and Ca(2+), but Pb(2+) binds predominantly with sidechain Glu (38.4%), which is less prevalent in both non-EF-Hand (10.4%) and EF-Hand (26.6%) Ca(2+)-binding sites. A comparison of binding geometries where Pb(2+) has replaced Ca(2+) in calmodulin (CaM) and Zn(2+) in 5-aminolaevulinic acid dehydratase (ALAD) revealed protein structural changes that appear to be unrelated to ionic displacement. Structural changes observed with CaM may be related to opportunistic binding of Pb(2+) in regions of high electrostatic charge, whereas ALAD may bind multiple Pb(2+) ions in the active site. These results suggest that Pb(2+) adapts to structurally-diverse binding geometries and that opportunistic binding may play an active role in molecular metal toxicity.
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Affiliation(s)
- Michael Kirberger
- Center for Drug Design and Biotechnology, Department of Chemistry, Georgia State University, 50 Decatur Street, 550 NSC, Atlanta, GA 30303, USA
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Abstract
This review attempts to touch on the history and application of amperometry at PC12 cells for fundamental investigation into the exocytosis process. PC12 cells have been widely used as a model for neural differentiation and as such they have been used to examine the effects of differentiation on exocytotic release and specifically release at varicosities. In addition, dexamethasone-differentiated cells have been shown to have an increased number of releasable vesicles with increased quantal size, thereby allowing for an even broader range of applications including neuropharmacological and neurotoxicological studies. PC12 cells exhibiting large numbers of events have two distinct pools of vesicles, one about twice the quantal size of the other and each about half the total releasable vesicles. As will be outlined in this review, these cells have served as an extremely useful model of exocytosis in the study of the latency of stimulation-release coupling, the role of exocytotic proteins in regulation of release, effect of drugs on quantal size, autoreceptors, fusion pore biophysics, environmental factors, health and disease. As PC12 cells have some advantages over other models for neurosecretion, including chromaffin cells, it is more than likely that in the following decade PC12 cells will continue to serve as a model to study exocytosis.
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Affiliation(s)
- R H S Westerink
- Cellular and Molecular Toxicology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands.
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40
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Cuenot F, Meyer M, Espinosa E, Bucaille A, Burgat R, Guilard R, Marichal-Westrich C. New Insights into the Complexation of Lead(II) by 1,4,7,10-Tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane (DOTAM): Structural, Thermodynamic, and Kinetic Studies. Eur J Inorg Chem 2008. [DOI: 10.1002/ejic.200700819] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Gourlaouen C, Parisel O. Is an Electronic Shield at the Molecular Origin of Lead Poisoning? A Computational Modeling Experiment. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200603037] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Gourlaouen C, Parisel O. Is an Electronic Shield at the Molecular Origin of Lead Poisoning? A Computational Modeling Experiment. Angew Chem Int Ed Engl 2007; 46:553-6. [PMID: 17152108 DOI: 10.1002/anie.200603037] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Christophe Gourlaouen
- Laboratoire de Chimie Théorique-UMR 7616 CNRS/UPMC, Université Pierre et Marie Curie-Paris 6, Case Courrier 137-4, place Jussieu, 75252 Paris CEDEX 05, France.
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Esposito A, Robello M, Pellistri F, Marchetti C. Two-photon analysis of lead accumulation in rat cerebellar granule neurons. Neurochem Res 2006; 30:949-54. [PMID: 16258843 DOI: 10.1007/s11064-005-5980-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/16/2005] [Indexed: 11/26/2022]
Abstract
Lead (Pb2+) is a common pollutant and potent central neurotoxin. We have studied its pathways of permeation by two-photon fluorescence microscopy in rat cerebellar granule neurons loaded with the fluorescent dye indo-1. Pb2+ binds indo-1 with high affinity acting as a quencher. Its permeation through the neuronal membrane was indicated by a decrease of the fluorescence emission, which occurred even in resting condition. In the presence of 20 microM Pb2+, uptake reached a plateau level (approximately 45% of initial fluorescence) in 4 min and was partially antagonized by 25 microM lanthanum. Subsequent addition of a membrane permeant ionophore caused a further (>70%) quenching of the dye, suggesting that previous saturation was due to inactivation of the transport system. Intracellular Pb2+ concentrations were evaluated from the fluorescence intensity and this estimate indicated that the concentration of free Pb2+ sufficient to inactivate the transport system is close to 50 pM.
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Affiliation(s)
- Alessandro Esposito
- INFM, Dipartimento di Fisica, Università di Genova, via Dodecaneso, 33, 16146, Genova, Italy
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Kapur P, Kaur K, Mahmood A. Expression of brush border enzymes in response to lead exposure in rat intestine. J Appl Toxicol 2005; 25:361-4. [PMID: 16092086 DOI: 10.1002/jat.1079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The effect of feeding lead (50 mg kg(-1) body weight) daily for 7 days on the development of various brush border enzymes in the intestine has been studied. The activities of brush border sucrase (P < 0.001), lactase (P < 0.001), gamma-glutamyl transpeptidase (P < 0.05) and leucine aminopeptidase were reduced (P < 0.05), whereas the alkaline phosphatase level was augmented (P < 0.05) in lead fed rats compared with controls. Kinetic studies with sucrase revealed a low Vmax (0.224 in control and 0.160 units mg(-1) protein in lead exposed) with no change in Km (12.6-13.5 mM). Western blot analysis for alkaline phosphatase yielded intense staining of enzyme protein in lead fed rats compared with controls, however, the intensity of the antigen signal was reversed for sucrase under these conditions. These findings suggest that ingestion of lead may interfere with the crypt cell differentiation process thus affecting enzyme functions in the rat intestine.
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Affiliation(s)
- Priya Kapur
- Department of Biochemistry, Panjab University, Chandigarh-160 014, India
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Counter SA, Buchanan LH, Ortega F. Neurocognitive impairment in lead-exposed children of Andean lead-glazing workers. J Occup Environ Med 2005; 47:306-12. [PMID: 15761328 DOI: 10.1097/01.jom.0000155717.45594.65] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The level of lead (Pb) exposure necessary to induce intellectual impairment has not been firmly established. Some studies using conventional language-based intelligence tests have reported that pediatric blood lead (PbB) levels lower than 10 microg/dL (0.483 micromol/L) are associated with neurocognitive impairment. However, these tests may introduce cultural biases in the assessment of intellectual functioning. The objective of this study was to assess the effects of PbB concentration on nonverbal intelligence in Andean children with chronic environmental Pb exposure using a nonlanguage-based test of cognitive functioning. METHODS Using Raven Colored Progressive Matrices (RCPM) as a measure of nonverbal intelligence, this study investigated the effects of Pb exposure (biomarker: PbB levels) on intellectual functioning in 188 chronically Pb-exposed children (age range: 5.33-11.67 years) of Ecuadorian Andean Pb-glazing workers. RESULTS The mean PbB level of the 188 children was 29.3 microg/dL (range: 3.5-94.3 microg/dL). Forty-seven children had PbB levels <10 microg/dL (Centers for Disease Control and Prevention [CDC] I classification), of which 30 had abnormal (ie, < or =25th percentile) RCPM standard scores. Of the 141 children with PbB levels > or =10 microg/dL, 97 had abnormal RCPM scores. A regression analysis revealed a statistically significant negative association (r = -0.331, P < 0.0001) between PbB level and RCPM standard score. Conversion of RCPM standard scores to estimated IQ scores showed an approximate two-point decrease in IQ for each 10-microg/dL increment in PbB level from 10 to >70 microg/dL. CONCLUSIONS Performance on a test of nonverbal intelligence was inversely associated with chronic Pb exposure in Andean children with PbB levels below and above the CDC risk management level of 10 microg/dL, with the decline in test scores suggesting a dose-response relationship.
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Affiliation(s)
- S Allen Counter
- Department of Neurology, Harvard Medical School/The Biological Laboratories, 16 Divinity Avenue, Cambridge, MA 02138, USA.
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Abstract
Several members of the synaptotagmin (syt) family of vesicle proteins have been proposed to act as Ca2+ sensors on synaptic vesicles. The mechanism by which calcium activates this class of proteins has been the subject of controversy, yet relatively few detailed biophysical studies have been reported on how isoforms other than syt I respond to divalent metal ions. Here, we report a series of studies on the response of syt II to a wide range of metal ions. Analytical ultracentrifugation studies demonstrate that Ca2+ induces protein dimerization upon exposure to 5 mM Ca2+. Whereas Ba2+, Mg2+, or Sr2+ do not potentiate self-association as strongly as Ca2+, Pb2+ triggers self-association of syt II at concentrations as low as 10 microM. Partial proteolysis studies suggest that the various divalent metals cause different changes in the conformation of the protein. The high calcium concentrations required for self-association of syt II suggest that the oligomerized state of this protein is not a critical intermediate in vesicle fusion; however, low-affinity calcium sites on syt II may play a critical role in buffering calcium at the presynaptic active zone. In addition, the high propensity of lead to oligomerize syt II offers a possible molecular explanation for how lead interferes with calcium-evoked neurotransmitter release.
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Affiliation(s)
- Ricardo A García
- Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, Evanston, Illinois 60208, USA
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47
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Counter SA, Buchanan LH, Ortega F. Current pediatric and maternal lead levels in blood and breast milk in Andean inhabitants of a lead-glazing enclave. J Occup Environ Med 2004; 46:967-73. [PMID: 15354063 DOI: 10.1097/01.jom.0000137712.21963.76] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Prenatal and postnatal lead (Pb) exposure may induce neurodevelopmental disabilities in children. As part of an ongoing health-monitoring study, blood lead (PbB) levels were compared in 90 children tested in 2003 (current group) and 166 children tested between 1996 and 2000 (reference group) in Ecuadorian Andean villages with high Pb contamination. The mean PbB level for children in the reference group was 40 microg/dL (range, 6.2-119.1), and significantly higher than the mean PbB level of 25.5 microg/dL (range, 2.1-94.3) for the current group (t test, P = 0.0001). An analysis of variance revealed no significant main effects for age and gender and no significant interaction between age and gender for the current group but a significant age by gender interaction for the reference group (F = 5.96, P = 0.01). Regression analysis revealed a significant correlation (r = 0.258, P = 0.01) between PbB level and age for males but not for females in the reference group. The Pb levels in breast milk from nursing mothers ranged from 0.4-20.5 microg/L (mean, 4.6), and the PbB levels in the breastfeeding mothers ranged from 4.5-35.2 microg/dL (mean, 17.1). The PbB levels of mother-infant pairs ranged from 4.6-27.4 microg/dL for mothers and 3.9-33.5 microg/dL for infants. The results showed significantly reduced PbB levels in children in the study area and suggest that a Pb education and prevention program contributed to the current reduction in Pb intoxication.
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Affiliation(s)
- S Allen Counter
- Department of Neurology, Harvard Medical School, Cambridge, MA 02138, USA.
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Suszkiw JB. Presynaptic disruption of transmitter release by lead. Neurotoxicology 2004; 25:599-604. [PMID: 15183013 DOI: 10.1016/j.neuro.2003.09.009] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2003] [Accepted: 09/09/2003] [Indexed: 11/24/2022]
Abstract
Low concentrations of inorganic lead ions (Pb2+) disrupt transmitter release by causing aberrant augmentation of spontaneous and suppression of evoked release. These effects result from high affinity interactions of Pb2+ with the voltage-gated calcium channels (VGCC) as well as Ca2+ binding proteins which regulate the synaptic vesicle mobilization, docking, and exocytosis processes. Augmentation of spontaneous release may involve stimulation of vesicle mobilization consequent to Pb2+ activation of CaMKII-dependent phosphorylation of synapsin I and/or stimulation of asynchronous exocytosis via direct Pb2+ activation of the putative exocytotic Ca2+-sensor protein synaptotagmin I. In addition, synergistic stimulation of PLC and DAG/Pb2+-dependent activation of PKC may enhance the secretagogue effects of Pb2+ by increasing metal sensitivity of exocytosis and/or modulating calcium channel activity. In contrast to intracellularly-mediated actions of Pb2+ resulting in augmentation of spontaneous release, the inhibition of evoked transmitter release by Pb2+ is largely attributable to extracellular block of the voltage-gated calcium channels.
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Affiliation(s)
- Janusz B Suszkiw
- Department of Cellular and Molecular Physiology, College of Medicine, University of Cincinnati, P.O. Box 670576, Cincinnati, OH 45267-0576, USA.
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Gill KD, Gupta V, Sandhir R. Ca2+/calmodulin-mediated neurotransmitter release and neurobehavioural deficits following lead exposure. Cell Biochem Funct 2004; 21:345-53. [PMID: 14624473 DOI: 10.1002/cbf.1030] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The present study was designed to investigate the effect of in vitro and in vivo lead exposure on calmodulin-mediated neurotransmitter release from synaptic vesicles with a view to explain the mechanism involved in its behavioural effects. It was observed that lead stimulated calmodulin, in terms of its ability to activate cAMP phosphodiesterase, following in vitro and in vivo exposure. Lead was also seen to enhance calmodulin-mediated synaptic vesicle protein phosphorylation. The increase in lead-induced synaptic vesicle protein phosphorylation was accompanied by enhanced release of acetylcholine from synaptic vesicles following in vitro lead exposure by a calmodulin-dependent mechanism. The ability of Ca(2+)/calmodulin to evoke acetylcholine release was reduced in the synaptic vesicles isolated from lead-exposed animals. Concomitantly, the levels of acetylcholine were found to decrease by 37.8% in the lead-treated animals as compared to the controls. The neurochemical alterations following lead exposure were accompanied by neurobehavioural deficits in terms of impaired motor and cognitive functions. The results from the present study clearly suggest that lead exerts its neurotoxic effects by interfering with Ca(2+)/calmodulin-mediated neurotransmitter release that is eventually responsible for behavioural impairment.
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Affiliation(s)
- K D Gill
- Department of Biochemistry, Postgraduate Institute of Medical Education and Research, Panjab University, Chandigarh 160012, India
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Atchison WD. Neurotoxicants and Synaptic Function: Session VII-B Summary and Research Needs. Neurotoxicology 2004; 25:515-9. [PMID: 15183005 DOI: 10.1016/j.neuro.2003.11.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- William D Atchison
- Department of Pharmacology/Toxicology, Michigan State University, Life Science Bldg. B-331, East Lansing, MI 48824-1317, USA.
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