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Carretero VJ, Liccardi N, Tejedor MA, de Pascual R, Campano JH, Hernández-Guijo JM. Lead exerts a depression of neurotransmitter release through a blockade of voltage dependent calcium channels in chromaffin cells. Toxicology 2024; 505:153809. [PMID: 38648961 DOI: 10.1016/j.tox.2024.153809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 04/08/2024] [Accepted: 04/17/2024] [Indexed: 04/25/2024]
Abstract
The present work, using chromaffin cells of bovine adrenal medullae (BCCs), aims to describe what type of ionic current alterations induced by lead (Pb2+) underlies its effects reported on synaptic transmission. We observed that the acute application of Pb2+ lead to a drastic depression of neurotransmitters release in a concentration-dependent manner when the cells were stimulated with both K+ or acetylcholine, with an IC50 of 119,57 μM and of 5,19 μM, respectively. This effect was fully recovered after washout. Pb2+ also blocked calcium channels of BCCs in a time- and concentration-dependent manner with an IC50 of 6,87 μM. This blockade was partially reversed upon washout. This compound inhibited the calcium current at all test potentials and shows a shift of the I-V curve to more negative values of about 8 mV. The sodium current was not blocked by acute application of high Pb2+ concentrations. Voltage-dependent potassium current was also shortly affected by high Pb2+. Nevertheless, the calcium- and voltage-dependent potassium current was drastically depressed in a dose-dependent manner, with an IC50 of 24,49 μM. This blockade was related to the prevention of Ca2+ influx through voltage-dependent calcium channels coupled to Ca2+-activated K+-channels (BK) instead a direct linking to these channels. Under current-clamp conditions, BCCs exhibit a resting potential of -52.7 mV, firing spontaneous APs (1-2 spikes/s) generated by the opening of Na+ and Ca2+-channels, and terminated by the activation of K+ channels. In spite of the effect on ionic channels exerted by Pb2+, we found that Pb2+ didn't alter cellular excitability, no modification of the membrane potential, and no effect on action potential firing. Taken together, these results point to a neurotoxic action evoked by Pb2+ that is associated with changes in neurotransmitter release by blocking the ionic currents responsible for the calcium influx.
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Affiliation(s)
- Victoria Jiménez Carretero
- Department of Pharmacology and Therapeutic, Facultad de Medicina, Univ. Autónoma de Madrid, Av. Arzobispo Morcillo 4, Madrid 28029, Spain
| | - Ninfa Liccardi
- Department of Pharmacology and Therapeutic, Facultad de Medicina, Univ. Autónoma de Madrid, Av. Arzobispo Morcillo 4, Madrid 28029, Spain
| | - Maria Arribas Tejedor
- Department of Pharmacology and Therapeutic, Facultad de Medicina, Univ. Autónoma de Madrid, Av. Arzobispo Morcillo 4, Madrid 28029, Spain
| | - Ricardo de Pascual
- Department of Pharmacology and Therapeutic, Facultad de Medicina, Univ. Autónoma de Madrid, Av. Arzobispo Morcillo 4, Madrid 28029, Spain
| | - Jorge Hernández Campano
- Department of Pharmacology and Therapeutic, Facultad de Medicina, Univ. Autónoma de Madrid, Av. Arzobispo Morcillo 4, Madrid 28029, Spain
| | - Jesús M Hernández-Guijo
- Department of Pharmacology and Therapeutic, Facultad de Medicina, Univ. Autónoma de Madrid, Av. Arzobispo Morcillo 4, Madrid 28029, Spain; Ramón y Cajal Institute for Health Research, IRYCIS, Hospital Ramón y Cajal, Ctra. de Colmenar Viejo, Km. 9,100, Madrid 28029, Spain.
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Zhou R, Huang C, Bi N, Li L, Li C, Gu X, Song Y, Wang HL. Chronic Pb Exposure Induces Anxiety and Depression-like Behaviors in Mice via Excitatory Neuronal Hyperexcitability in Ventral Hippocampal Dentate Gyrus. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:12222-12233. [PMID: 37559393 DOI: 10.1021/acs.est.3c03426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/11/2023]
Abstract
Lead (Pb) is a widespread neurotoxic pollutant. Pb exposure is associated with mood disorders, with no well-established neural mechanisms elucidated. In the present study, we aimed to investigate whether excitatory neurons in the dentate gyrus subregion of the ventral hippocampus (vDG) played a key role in Pb-induced anxiety and depression-like behaviors. C57BL/6 mice were exposed to 100 ppm Pb starting on day 1 of pregnancy until experiments were performed using the offspring. Behavioral studies suggested that chronic Pb exposure triggered anxiety and depression-like behaviors. A combination of electrophysiological, optogenetic, and immunohistochemistry experiments was conducted. Results showed that Pb exposure resulted in excitatory neuronal hyperexcitability in vDG and that the behavioral deficits caused by Pb exposure could be rescued by inhibition of excitatory neuronal activity. Moreover, it was found that the action potential (AP) threshold of excitatory neurons was decreased by electrophysiological recordings. Our study demonstrates a significant role for excitatory neurons in vDG in Pb-induced anxiety and depression-like behaviors in mice, which is likely a result of decreased AP threshold. These outcomes can serve as an important basis for understanding mechanisms of anxiety and depression under environmental Pb exposure and help in the design of therapeutic strategies.
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Affiliation(s)
- Ruiqing Zhou
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230000, Anhui, PR China
| | - Chengqing Huang
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230000, Anhui, PR China
| | - Nanxi Bi
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230000, Anhui, PR China
| | - Ling Li
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230000, Anhui, PR China
| | - Changqing Li
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230000, Anhui, PR China
| | - Xiaozhen Gu
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230000, Anhui, PR China
| | - Yang Song
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China
| | - Hui-Li Wang
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230000, Anhui, PR China
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Ohtubo Y. Slow recovery from the inactivation of voltage-gated sodium channel Nav1.3 in mouse taste receptor cells. Pflugers Arch 2021; 473:953-968. [PMID: 33881614 DOI: 10.1007/s00424-021-02563-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 04/02/2021] [Accepted: 04/04/2021] [Indexed: 02/06/2023]
Abstract
Action potentials play an important role in neurotransmitter release in response to taste. Here, I have investigated voltage-gated Na+ channels, a primary component of action potentials, in respective cell types of mouse fungiform taste bud cells (TBCs) with in situ whole-cell clamping and single-cell RT-PCR techniques. The cell types of TBCs electrophysiologically examined were determined immunohistochemically using the type III inositol 1,4,5-triphoshate receptor as a type II cell marker and synaptosomal-associated protein 25 as a type III cell marker. I show that type II cells, type III cells, and TBCs not immunoreactive to these markers (likely type I cells) generate voltage-gated Na+ currents. The recovery following inactivation of these currents was well fitted with double exponential curves. The time constants in type III cells (~20 ms and ~ 1 s) were significantly slower than respective time constants in other cell types. RT-PCR analysis indicated the expression of Nav1.3, Nav1.5, Nav1.6, and β1 subunit mRNAs in TBCs. Pharmacological inhibition and single-cell RT-PCR studies demonstrated that type II and type III cells principally express tetrodotoxin (TTX)-sensitive Nav1.3 channels and that ~ 30% of type I cells express TTX-resistant Nav1.5 channels. The auxiliary β1 subunit that modulates gating kinetics was rarely detected in TBCs. As the β1 subunit co-expressed with an α subunit is known to accelerate the recovery from inactivation, it is likely that voltage-gated Na+ channels in TBCs may function without β subunits. Slow recovery from inactivation, especially in type III cells, may limit high-frequency firing in response to taste substances.
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Affiliation(s)
- Yoshitaka Ohtubo
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Hibikino 2-4, Kitakyushu, 808-0196, Japan.
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Gao J, Zhang H, Xiong P, Yan X, Liao C, Jiang G. Application of electrophysiological technique in toxicological study: From manual to automated patch-clamp recording. Trends Analyt Chem 2020. [DOI: 10.1016/j.trac.2020.116082] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Bjørklund G, Dadar M, Chirumbolo S, Aaseth J. High Content of Lead Is Associated with the Softness of Drinking Water and Raised Cardiovascular Morbidity: A Review. Biol Trace Elem Res 2018; 186:384-394. [PMID: 29656350 DOI: 10.1007/s12011-018-1336-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 04/04/2018] [Indexed: 10/17/2022]
Abstract
Daily ingestion of lead (Pb), even through piped drinking water, has long time been an important issue of concern, attracting for decades research in environmental science and toxicology, and again comes to prominence because of recent high-profile cases of exposure of populations in several countries to Pb-contaminated water. Numerous studies have reported an association between Pb in water and the risk of cardiovascular pathologies. Low levels of magnesium and calcium, i.e., low degree of hardness of the drinking water, may accentuate Pb leaching from water pipes and furthermore increase Pb absorption. This review evaluates the evidence for an association between Pb exposure from drinking water and cardiovascular end points in human populations.
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Affiliation(s)
- Geir Bjørklund
- Council for Nutritional and Environmental Medicine, Toften 24, 8610, Mo i Rana, Norway.
| | - Maryam Dadar
- Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
| | - Salvatore Chirumbolo
- Department of Neurological and Movement Sciences, University of Verona, Verona, Italy
| | - Jan Aaseth
- Faculty of Public Health, Inland Norway University of Applied Sciences, Elverum, Norway
- Department of Research, Innlandet Hospital Trust, Brumunddal, Norway
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Lead poisoning: acute exposure of the heart to lead ions promotes changes in cardiac function and Cav1.2 ion channels. Biophys Rev 2017; 9:807-825. [PMID: 28836190 DOI: 10.1007/s12551-017-0303-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 07/28/2017] [Indexed: 01/02/2023] Open
Abstract
Lead ions (Pb2+) possess characteristics similar to Ca2+. Because of this and its redox capabilities, lead causes different toxic effects. The neurotoxic effects have been well documented; however, the toxic effects on cardiac tissues remain allusive. We utilized isolated guinea pig hearts and measured the effects of Pb2+ on their contractility and excitability. Acute exposure to extracellular Pb2+ had a negative inotropic effect and increased diastolic tension. The speed of contraction and relaxation were affected, though the effects were more dramatic on the speed of contraction. Excitability was also altered. Heart beat frequency increased and later diminished after lead ion exposure. Pro-arrhytmic events, such as early after-depolarization and a reduction of the action potential plateau, were also observed. In isolated cardiomyocytes and tsA 201 cells, extracellular lead blocked currents through Cav1.2 channels, diminished their activation, and enhanced their fast inactivation, negatively affecting their gating currents. Thus, Pb2+ was cardiotoxic and reduced cardiac contractility, making the heart prone to arrhythmias. This was due, in part, to Pb2+ effects on the Cav1.2 channels; however, other channels, transporters or pathways may also be involved. Acute cardiotoxic effects were observed at Pb2+ concentrations achievable during acute lead poisoning. The results suggest how Cav1.2 gating can be affected by divalent cations, such as Pb2, and also suggest a more thorough evaluation of heart function in individuals affected by lead poisoning.
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Cai T, Luo W, Ruan D, Wu YJ, Fox DA, Chen J. The History, Status, Gaps, and Future Directions of Neurotoxicology in China. ENVIRONMENTAL HEALTH PERSPECTIVES 2016; 124:722-732. [PMID: 26824332 PMCID: PMC4892912 DOI: 10.1289/ehp.1409566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 09/25/2015] [Accepted: 01/15/2016] [Indexed: 06/05/2023]
Abstract
BACKGROUND Rapid economic development in China has produced serious ecological, environmental, and health problems. Neurotoxicity has been recognized as a major public health problem. The Chinese government, research institutes, and scientists conducted extensive studies concerning the source, characteristics, and mechanisms of neurotoxicants. OBJECTIVES This paper presents, for the first time, a comprehensive history and review of major sources of neurotoxicants, national bodies/legislation engaged, and major neurotoxicology research in China. METHODS Peer-reviewed research and pollution studies by Chinese scientists from 1991 to 2015 were examined. PubMed, Web of Science and Chinese National Knowledge Infrastructure (CNKI) were the major search tools. RESULTS The central problem is an increased exposure to neurotoxicants from air and water, food contamination, e-waste recycling, and manufacturing of household products. China formulated an institutional framework and standards system for management of major neurotoxicants. Basic and applied research was initiated, and international cooperation was achieved. The annual number of peer-reviewed neurotoxicology papers from Chinese authors increased almost 30-fold since 2001. CONCLUSIONS Despite extensive efforts, neurotoxicity remains a significant public health problem. This provides great challenges and opportunities. We identified 10 significant areas that require major educational, environmental, governmental, and research efforts, as well as attention to public awareness. For example, there is a need to increase efforts to utilize new in vivo and in vitro models, determine the potential neurotoxicity and mechanisms involved in newly emerging pollutants, and examine the effects and mechanisms of mixtures. In the future, we anticipate working with scientists worldwide to accomplish these goals and eliminate, prevent and treat neurotoxicity. CITATION Cai T, Luo W, Ruan D, Wu YJ, Fox DA, Chen J. 2016. The history, status, gaps, and future directions of neurotoxicology in China. Environ Health Perspect 124:722-732; http://dx.doi.org/10.1289/ehp.1409566.
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Affiliation(s)
- Tongjian Cai
- Department of Occupational and Environmental Health, Ministry of Education Key Lab of Hazard Assessment and Control in Special Operational Environment, School of Public Health, Fourth Military Medical University, Xi’an, Shaanxi, China
- Department of Epidemiology, College of Preventive Medicine, Third Military Medical University, Chongqing, China
| | - Wenjing Luo
- Department of Occupational and Environmental Health, Ministry of Education Key Lab of Hazard Assessment and Control in Special Operational Environment, School of Public Health, Fourth Military Medical University, Xi’an, Shaanxi, China
| | - Diyun Ruan
- Neurotoxicology Lab, School of Life Science, University of Science and Technology of China, Hefei, Anhui, China
| | - Yi-Jun Wu
- Laboratory of Molecular Toxicology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Donald A. Fox
- College of Optometry,
- Department of Biology and Biochemistry,
- Department of Pharmacological and Pharmaceutical Sciences, and
- Department of Health and Human Performance, University of Houston, Houston, Texas, USA
| | - Jingyuan Chen
- Department of Occupational and Environmental Health, Ministry of Education Key Lab of Hazard Assessment and Control in Special Operational Environment, School of Public Health, Fourth Military Medical University, Xi’an, Shaanxi, China
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Wang J, Song L, Li K, Yan R, Hu X, Zhang W, Yin Y, Zhao S. Protective effects of lithium against lead-induced toxicities in multiple systems of adult mouse. Toxicol Res (Camb) 2015. [DOI: 10.1039/c5tx00071h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Occupational and environmental exposures to lead (Pb), one of the toxic metal pollutants, is of global concern.
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Affiliation(s)
- Jiutao Wang
- College of Veterinary Medicine
- Northwest A&F University
- Yangling
- People's Republic of China
| | - Lingzhen Song
- College of Veterinary Medicine
- Northwest A&F University
- Yangling
- People's Republic of China
| | - Kaikai Li
- College of Veterinary Medicine
- Northwest A&F University
- Yangling
- People's Republic of China
| | - Runchuan Yan
- College of Veterinary Medicine
- Northwest A&F University
- Yangling
- People's Republic of China
| | - Xinde Hu
- College of Veterinary Medicine
- Northwest A&F University
- Yangling
- People's Republic of China
| | - Wei Zhang
- College of Veterinary Medicine
- Northwest A&F University
- Yangling
- People's Republic of China
| | - Yupeng Yin
- College of Veterinary Medicine
- Northwest A&F University
- Yangling
- People's Republic of China
| | - Shanting Zhao
- College of Veterinary Medicine
- Northwest A&F University
- Yangling
- People's Republic of China
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Fan G, Zhou F, Feng C, Wu F, Ye W, Wang C, Lin F, Yan J, Li Y, Chen Y, Bi Y. Lead-induced ER calcium release and inhibitory effects of methionine choline in cultured rat hippocampal neurons. Toxicol In Vitro 2012; 27:387-95. [PMID: 22921426 DOI: 10.1016/j.tiv.2012.06.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 06/25/2012] [Accepted: 06/28/2012] [Indexed: 11/19/2022]
Abstract
Lead, a ubiquitous neurotoxicant, can result in learning and memory dysfunction. Long term potentiation in the hippocampus, a potential neural substrate for learning and memory, is thought to be linked to calcium-triggered intracellular events. In this study, laser scanning confocal microscopy was used to examine the effects of Pb(2+) on intracellular and endoplasmic reticulum free calcium concentration ([Ca(2+)](i) and [Ca(2+)](ER)) in cultured neonatal rat hippocampal neurons and their possible antagonism by methionine choline; understanding these effects would help explain the lead-induced cognitive and learning dysfunction and explore efficient safety and relief strategies. The results showed that Pb(2+) increased [Ca(2+)](i) and decreased [Ca(2+)](ER) linearly in a time- and concentration-dependant manner, and Pb(2+) addition after the applying of a ryanodine receptor (RyR) antagonist and an inositol-1,4,5-triphosphate receptor (IP(3)R) antagonist did not increase [Ca(2+)](i). The addition of 10, 20, or 40 mmol/L methionine choline simultaneously with addition of 10 μmol/L Pb(2+) decreased [Ca(2+)](i) in Ca(2+)-free culture medium by 39.0%, 66.0%, and 61.6%, respectively, in a concentration-dependant manner in a certain dose range. Our results suggest that Pb(2+) induces ER calcium release to increase the resting [Ca(2+)](i); and methionine choline inhibit this increase in [Ca(2+)](i).
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Affiliation(s)
- Guangqin Fan
- Department of Occupational Health and Toxicology, School of Public Health, Nanchang University, BaYi Road 461, Nanchang 330006, PR China.
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Luo W, Ruan D, Yan C, Yin S, Chen J. Effects of chronic lead exposure on functions of nervous system in Chinese children and developmental rats. Neurotoxicology 2012; 33:862-71. [DOI: 10.1016/j.neuro.2012.03.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 03/09/2012] [Accepted: 03/20/2012] [Indexed: 01/23/2023]
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Nava-Ruiz C, Méndez-Armenta M, Ríos C. Lead neurotoxicity: effects on brain nitric oxide synthase. J Mol Histol 2012; 43:553-63. [PMID: 22526509 DOI: 10.1007/s10735-012-9414-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 04/02/2012] [Indexed: 12/23/2022]
Abstract
Lead (Pb), a ubiquitous and potent neurotoxicant, induces several neurophysiological and behavioural changes, while Pb alters the function of multiple organs and systems, it primarily affects the central nervous system. In human adults, encephalopathy resulting from Pb intoxication is often characterized by sleeplessness, poor attention span, vomiting, convulsions and coma; in children, Pb-induced encephalopathy is associated with mental dullness, vomiting, irritability and anorexia; diminished cognitive function resulting in a mental deficit has been also observed during Prolonged exposure to Pb. Pb can produce oxidative stress, disrupt the blood-brain barrier and alter several Ca(2+)-dependent processes, including physiological processes that involve nitric oxide synthesis on central nervous system in development and adult animals. This review summarizes recent evidence showing that Pb can interfere with the production of nitric oxide and can disrupt the function of nitric oxide synthase. Lead interferes with nitric oxide-related physiological mechanisms, and Pb neurotoxicity may affect processes involved in learning and memory.
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Affiliation(s)
- Concepción Nava-Ruiz
- Lab. Neuropatología Experimental, Instituto Nacional de Neurología y Neurocirugía Manuel Velasco Suárez, Mexico City, Mexico
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Hao S, Bao YM, Zhao RG, Wang HS, Bi J, An LJ, Jiang B. Effects of resibufogenin on voltage-gated sodium channels in cultured rat hippocampal neurons. Neurosci Lett 2011; 501:112-6. [DOI: 10.1016/j.neulet.2011.06.059] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 06/29/2011] [Accepted: 06/29/2011] [Indexed: 11/16/2022]
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Zhang GS, Ye WF, Tao RR, Lu YM, Shen GF, Fukunaga K, Huang JY, Ji YL, Han F. Expression profiling of Ca(2+)/calmodulin-dependent signaling molecules in the rat dorsal and ventral hippocampus after acute lead exposure. ACTA ACUST UNITED AC 2010; 64:619-24. [PMID: 21195594 DOI: 10.1016/j.etp.2010.12.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Revised: 11/22/2010] [Accepted: 12/05/2010] [Indexed: 11/26/2022]
Abstract
The septal and temporal poles of the hippocampus differ markedly in their anatomical organization, but whether these distinct regions exhibit differential neurochemical profiles underlying lead (Pb(2+)) neurotoxicity remains to be determined. In the present study, we examined changes in the expression of Ca(2+)/calmodulin-dependent enzymes, including calpain, calcineurin, phospho-CaMKII (Thr286) and neuronal nitric oxide synthase (nNOS), in the rat dorsal and ventral hippocampus (DH and VH) after acute Pb(2+) exposure. Five days after Pb(2+) exposure, we observed constitutively active forms of calcineurin (45 kDa and 48 kDa) in ventral portions of the hippocampus, a result consistent with the observed calpain activation that is indicated by the breakdown of spectrin in this region. Our data demonstrate that nNOS expression is significantly higher in the ventral region of the hippocampus when compared to the dorsal region, whereas phosphorylation of CaMKII (Thr286) is less pronounced in the ventral portion of the hippocampus and more pronounced in dorsal regions after acute Pb(2+) exposure. Thus, it appears likely that the ventral region of hippocampus is more vulnerable to the neurotoxic effects of Pb(2+) than the dorsal region. Taken together, the present data suggest that acute lead exposure leads to differential expression patterns of Ca(2+)/calmodulin-dependent enzymes along the dorsoventral axis of the hippocampus.
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Affiliation(s)
- Gen-sheng Zhang
- Institute of Pharmacology, Toxicology and Biochemical Pharmaceutics, Zhejiang University, Hangzhou 310058, China
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Bokara KK, Blaylock I, Denise SB, Bettaiya R, Rajanna S, Yallapragada PR. Influence of lead acetate on glutathione and its related enzymes in different regions of rat brain. J Appl Toxicol 2010; 29:452-8. [PMID: 19263481 DOI: 10.1002/jat.1423] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
This study is intended to determine the effect of lead acetate on glutathione and its associated enzymes of rat brain. Wistar male rats were treated with lead acetate (500 ppm) through drinking water for a period of 8 weeks and parallel controls were maintained. They were sacrificed at the first, fourth and eighth week to isolate whole brains, which were separated into cerebellum, hippocampus, frontal cortex and brain stem. The data indicate enhanced (P < 0.05) glutathione peroxidase (G-Px) activity at most of the intervals for cerebellum, frontal cortex and brain stem, suggesting conversion of GSH to GSSG, while the hippocampus showed decreased levels. In contrast, glutathione reductase (GR) decreased significantly (P < 0.05) in cerebellum, frontal cortex and brain stem at all intervals except the fourth week in frontal cortex and brain stem. Hippocampus exhibited a gradual and significant (P < 0.05) increase in GR activity. Glutathione-S-transferase (GSTase) activity increased with exposure time in all four brain tissues, showing protection against lead acetate toxicity. The GSH and GSSG levels correlated well with the activities of GPx, GR and GSTase in all four regions of the brain. Overall the results indicate that lead acetate affects glutathione-related enzymes differentially and these changes can be attributed to differences in tissue susceptibility.
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Bennet C, Bettaiya R, Rajanna S, Baker L, Yallapragada PR, Brice JJ, White SL, Bokara KK. Region specific increase in the antioxidant enzymes and lipid peroxidation products in the brain of rats exposed to lead. Free Radic Res 2009; 41:267-73. [PMID: 17364954 DOI: 10.1080/10715760600889855] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The objective of this study is to determine the effect of lead (pb) on antioxidant enzymes and lipid peroxidation products in different regions of rat brain. Wistar male rats were treated with lead acetate (500 ppm) through drinking water for a period of 8 weeks. Control animals were maintained on sodium acetate. Treated and control rats were sacrificed at intervals of 1st, 4th and 8th week and the whole brains were dissected on ice into four regions namely the cerebellum, the hippocampus, the frontal cortex and the brain stem. Antioxidant enzymes namely catalase and superoxide dismutase in all the four regions of brain were determined. In addition, lipid peroxidation products were also estimated. The results indicated a gradual increase in the activity of antioxidant enzymes in different regions of the brain and this response was time-dependent. However, the increase was more in the cerebellum and the hippocampus compared to other regions of the brain. The lipid peroxidation products also showed a similar trend suggesting increased effect of lead in these two regions of the brain. The data indicated a region-specific oxidative stress in the brain exposed to lead.
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Affiliation(s)
- Christopher Bennet
- Department of Biological Sciences, Alcorn State University, Lorman, MS 39096, USA
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Yan D, Xiao C, Ma FL, Wang L, Luo YY, Liu J, Wang HL, Chen JT, Ruan DY. Excitatory effects of low-level lead exposure on action potential firing of pyramidal neurons in CA1 region of rat hippocampal slices. J Neurosci Res 2008; 86:3665-73. [DOI: 10.1002/jnr.21804] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Effects of SO2 derivatives on sodium currents in acutely isolated rat hippocampal lead-exposed neurons. SCIENCE IN CHINA. SERIES C, LIFE SCIENCES 2008; 51:802-7. [PMID: 18726526 DOI: 10.1007/s11427-008-0098-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2007] [Accepted: 06/12/2008] [Indexed: 10/21/2022]
Abstract
In this study, the effects of acute SO2 derivatives and chronic lead exposure together on sodium currents (I(Na)) were investigated in acutely isolated rat hippocampal neurons by using the whole-cell patch clamp techniques. We found that chronic lead exposure hardly reduced the amplitudes of I(Na). In the normal condition, sodium current started to appear at around -70 mV, and reached the peak current at around -40 mV. After chronic lead exposure, the data changed to -70 and -30 mV. After adding SO2 derivatives, the data changed to -80 and -40 mV, respectively. SO2 derivatives caused a significant increase of I(Na) in hippocampal chronic-lead exposed neurons. Chronic lead exposure induced a right shift of the activation curve and a left shift of the inactivation curve of sodium channels. SO2 derivatives caused negative shifts of the activation and inactivation curves of I(Na) in hippocampal chronic-lead exposed neurons. Lead exposure put off the time reaching the peak of I(Na) activation. SO2 derivatives increased the time constants of inactivation after lead exposure. The interaction of lead and SO2 derivatives with voltage-dependent sodium channels may lead to changes in electrical activity and contribute to worsening the neurotoxicological damage.
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Yan D, Wang L, Ma FL, Deng H, Liu J, Li C, Wang H, Chen J, Tang JL, Ruan DY. Developmental exposure to lead causes inherent changes on voltage-gated sodium channels in rat hippocampal CA1 neurons. Neuroscience 2008; 153:436-45. [DOI: 10.1016/j.neuroscience.2008.02.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2007] [Revised: 01/20/2008] [Accepted: 02/14/2008] [Indexed: 12/29/2022]
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Sun H, Wang HL, Wang S. d-serine relieves chronic lead exposure-impaired long-term potentiation in the CA1 region of the rat hippocampus in vitro. Neurosci Lett 2007; 417:118-22. [PMID: 17408856 DOI: 10.1016/j.neulet.2007.01.085] [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] [Received: 12/01/2006] [Revised: 01/19/2007] [Accepted: 01/28/2007] [Indexed: 11/28/2022]
Abstract
Chronic lead-exposure produces long-lasting astroglial morphological and functional changes, which disturb the neuronal functions in the hippocampus. It has been shown that glia-derived D-serine is an essential signal for N-methyl-D-aspartate receptor (NMDAR)-dependent synaptic plasticity in the hippocampal CA1 region. However, the relationship between d-serine and the chronic lead exposure-induced deficit of synaptic plasticity is not clear. In the present study, the properties of D-serine on the chronic lead exposure-impaired synaptic plasticity in the rat hippocampal CA1 region were investigated with electrophysiological recording techniques in vitro. We found that 50 microM D-serine rescued the chronic lead exposure-induced deficit of long-term potentiation (LTP). However, this effect could be abolished by 7-chlorokynurenic acid (7-ClKY), which is a specific antagonist of the glycine-binding site of NMDARs. In contrast, D-serine had no effect on the NMDAR-independent LTP, which was induced in the mossy-CA3 synapses. In addition, we found that d-serine rescued the acute Pb(2+)-impaired NMDAR-mediated excitatory postsynaptic currents (EPSCs) partially. These findings demonstrate that d-serine relieves the chronic lead exposure-induced deficit of synaptic plasticity via NMDAR activation suggesting that administration of d-serine may be a potential therapeutic intervention to treat chronic lead exposure-impaired cognitive functions or affective disorders.
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Affiliation(s)
- Hao Sun
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Science, University of Science and Technology of China, Hefei, Anhui, PR China
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