1
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Kim SY, Kim M, Lim YK, Baek SH, Kim JY, An KG, Hong S. First investigation of the temporal distribution of neurotoxin β-N-methylamino-L-alanine (BMAA) and the candidate causative microalgae along the South Sea Coast of Korea. JOURNAL OF HAZARDOUS MATERIALS 2024; 478:135486. [PMID: 39151364 DOI: 10.1016/j.jhazmat.2024.135486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2024] [Revised: 08/05/2024] [Accepted: 08/09/2024] [Indexed: 08/19/2024]
Abstract
The neurotoxin β-N-methylamino-L-alanine (BMAA), produced by cyanobacteria and diatoms, has been implicated as an environmental risk factor for neurodegenerative diseases. This study first investigated the occurrence and monthly distributions of BMAA and its isomers, 2,4-diaminobutyric acid (DAB) and N-2-aminoethylglycine (AEG), in phytoplankton and mussels from 11 sites along the South Sea Coast of Korea throughout 2021. These toxins were quantified using LC-MS/MS, revealing elevated BMAA concentrations from late autumn to spring, with phase lags observed between phytoplankton and mussels. The highest concentration of BMAA in phytoplankton was detected in November (mean: 1490 ng g-1 dry weight (dw)), while in mussels, it peaked in December (mean: 1240 ng g-1 dw). DAB was detected in phytoplankton but was absent in mussels, indicating limited bioaccumulation potential. In February, the peak mean DAB concentration in phytoplankton was 89 ng g-1 dw. AEG was not detected in any samples. Chlorophyll-a concentrations consistently showed an inverse correlation with BMAA concentrations in mussels throughout the year. Through correlation analysis, four diatom genera, Bacillaria, Hemiaulus, Odontella, and Pleurosigma, were identified as potential causative microalgae of BMAA. This study offers insights into identifying the causative microalgae for BMAA and informs future regulatory efforts regarding unmanaged biotoxins.
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Affiliation(s)
- Sea-Yong Kim
- Department of Marine Environmental Sciences & Institute of Marine Environmental Sciences, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Mungi Kim
- Department of Earth, Environmental & Space Sciences, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Young Kyun Lim
- Ecological Risk Research Department, Korea Institute of Ocean Science and Technology, Geoje 53201, Republic of Korea
| | - Seung Ho Baek
- Ecological Risk Research Department, Korea Institute of Ocean Science and Technology, Geoje 53201, Republic of Korea
| | - Ji Yoon Kim
- Department of Bioscience and Biotechnology, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Kwang-Guk An
- Department of Bioscience and Biotechnology, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Seongjin Hong
- Department of Marine Environmental Sciences & Institute of Marine Environmental Sciences, Chungnam National University, Daejeon 34134, Republic of Korea; Department of Earth, Environmental & Space Sciences, Chungnam National University, Daejeon 34134, Republic of Korea.
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2
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Nguyen PQ, Huang X, Collins DS, Collins JJ, Lu T. Harnessing synthetic biology to enhance ocean health. Trends Biotechnol 2023; 41:860-874. [PMID: 36669947 DOI: 10.1016/j.tibtech.2022.12.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 12/16/2022] [Accepted: 12/22/2022] [Indexed: 01/19/2023]
Abstract
Ocean health is faltering, its capability for regeneration and renewal being eroded by a steady pulse of anthropomorphic impacts. Plastic waste has infiltrated all ocean biomes, climate change threatens coral reefs with extinction, and eutrophication has unleashed vast algal blooms. In the face of these challenges, synthetic biology approaches may hold untapped solutions to mitigate adverse effects, repair ecosystems, and put us on a path towards sustainable stewardship of our planet. Leveraging synthetic biology tools would enable innovative engineering approaches to augment the natural adaptive capacity of ocean biological systems to cope with the swiftness of human-induced change. Here, we present a framework for developing synthetic biology solutions for the challenges of plastic pollution, coral bleaching, and harmful algal blooms.
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Affiliation(s)
- Peter Q Nguyen
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
| | - Xiaoning Huang
- Department of Bioengineering, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Daniel S Collins
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA; Department of Biology and Nicholas School of the Environment, Duke University, Durham, NC, USA
| | - James J Collins
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA; Institute for Medical Engineering & Science, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA; Broad Institute of MIT and Harvard, Cambridge, MA, USA.
| | - Ting Lu
- Department of Bioengineering, University of Illinois Urbana-Champaign, Urbana, IL, USA; Carl R. Woese Institute for Genomic Biology, University of Illinois Urbana-Champaign, Urbana, IL, USA; Department of Physics, University of Illinois Urbana-Champaign, Urbana, IL, USA; Center for Biophysics and Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, IL, USA; National Center for Supercomputing Applications, University of Illinois Urbana-Champaign, Urbana, IL, USA.
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3
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Panlilio JM, Hammar KM, Aluru N, Hahn ME. Developmental exposure to domoic acid targets reticulospinal neurons and leads to aberrant myelination in the spinal cord. Sci Rep 2023; 13:2587. [PMID: 36788234 PMCID: PMC9929266 DOI: 10.1038/s41598-023-28166-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 01/13/2023] [Indexed: 02/16/2023] Open
Abstract
Harmful algal blooms (HABs) produce neurotoxins that affect human health. Developmental exposure of zebrafish embryos to the HAB toxin domoic acid (DomA) causes myelin defects, loss of reticulospinal neurons, and behavioral deficits. However, it is unclear whether DomA primarily targets myelin sheaths, leading to the loss of reticulospinal neurons, or reticulospinal neurons, causing myelin defects. Here, we show that while exposure to DomA at 2 dpf did not reduce the number of oligodendrocyte precursors prior to myelination, it led to fewer myelinating oligodendrocytes that produced shorter myelin sheaths and aberrantly wrapped neuron cell bodies. DomA-exposed larvae lacked Mauthner neurons prior to the onset of myelination, suggesting that axonal loss is not secondary to myelin defects. The loss of the axonal targets may have led oligodendrocytes to inappropriately myelinate neuronal cell bodies. Consistent with this, GANT61, a GLI1/2 inhibitor that reduces oligodendrocyte number, caused a reduction in aberrantly myelinated neuron cell bodies in DomA-exposed fish. Together, these results suggest that DomA initially alters reticulospinal neurons and the loss of axons causes aberrant myelination of nearby cell bodies. The identification of initial targets and perturbed cellular processes provides a mechanistic understanding of how DomA alters neurodevelopment, leading to structural and behavioral phenotypes.
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Affiliation(s)
- Jennifer M Panlilio
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, 02543, USA.
- Massachusetts Institute of Technology (MIT) - Woods Hole Oceanographic Institution (WHOI) Joint Graduate Program in Oceanography and Oceanographic Engineering, Cambridge, USA.
- Woods Hole Center for Oceans and Human Health, Woods Hole, MA, 02543, USA.
| | - Katherine M Hammar
- Central Microscopy Facility, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA, 02543, USA
| | - Neelakanteswar Aluru
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, 02543, USA
- Woods Hole Center for Oceans and Human Health, Woods Hole, MA, 02543, USA
| | - Mark E Hahn
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, 02543, USA
- Woods Hole Center for Oceans and Human Health, Woods Hole, MA, 02543, USA
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4
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Ushimaru R, Abe I. Unusual Dioxygen-Dependent Reactions Catalyzed by Nonheme Iron Enzymes in Natural Product Biosynthesis. ACS Catal 2022. [DOI: 10.1021/acscatal.2c05247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Richiro Ushimaru
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
- ACT-X, Japan Science and Technology Agency (JST), Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Ikuro Abe
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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5
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Li QZ, Hou SH, Kang JC, Lian PF, Hao Y, Chen C, Zhou J, Ding TM, Zhang SY. Bioinspired Palladium-Catalyzed Intramolecular C(sp 3 )-H Activation for the Collective Synthesis of Proline Natural Products. Angew Chem Int Ed Engl 2022; 61:e202207088. [PMID: 35751877 DOI: 10.1002/anie.202207088] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Indexed: 12/18/2022]
Abstract
Bioinspired palladium-catalyzed intramolecular cyclization of amino acid derivatives containing a vinyl iodide moiety by C-H activation enabled rapid access to a wide range of functionalized proline derivatives with an exocyclic olefin. To demonstrate the practicality of this methodology, the functionalized prolines were used as intermediates for the synthesis of several natural products: lucentamycin A, oxotomaymycin, oxoprothracarcin, and barmumycin.
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Affiliation(s)
- Quan-Zhe Li
- Shanghai Key Laboratory for Molecular Engineer of Chiral Drugs, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China.,School of Pharmaceutical Sciences, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Si-Hua Hou
- Shanghai Key Laboratory for Molecular Engineer of Chiral Drugs, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China.,School of Pharmaceutical Sciences, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Jun-Chen Kang
- Shanghai Key Laboratory for Molecular Engineer of Chiral Drugs, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Peng-Fei Lian
- Shanghai Key Laboratory for Molecular Engineer of Chiral Drugs, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Yu Hao
- Shanghai Key Laboratory for Molecular Engineer of Chiral Drugs, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Chao Chen
- Shanghai Key Laboratory for Molecular Engineer of Chiral Drugs, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Jia Zhou
- Shanghai Key Laboratory for Molecular Engineer of Chiral Drugs, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Tong-Mei Ding
- Shanghai Key Laboratory for Molecular Engineer of Chiral Drugs, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Shu-Yu Zhang
- Shanghai Key Laboratory for Molecular Engineer of Chiral Drugs, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
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6
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Li QZ, Hou SH, Kang JC, Lian PF, Hao Y, Chen C, Zhou J, Ding TM, Zhang SY. Bioinspired Palladium‐Catalyzed Intramolecular C(sp3)−H Activation for the Collective Synthesis of Proline Natural Products. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202207088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Quan-Zhe Li
- Shanghai Jiao Tong University Chemistry CHINA
| | - Si-Hua Hou
- SJTU: Shanghai Jiao Tong University CHEMISTRY CHINA
| | | | | | - Yu Hao
- SJTU: Shanghai Jiao Tong University Chemistry CHINA
| | - Chao Chen
- SJTU: Shanghai Jiao Tong University Chemistry CHINA
| | - Jia Zhou
- SJTU: Shanghai Jiao Tong University Chemistry CHINA
| | | | - Shu-Yu Zhang
- Shanghai Jiao Tong University School of Chemistry and Chemical Engineering 800 Dongchuan RoadB329 Chemsitry BuildingShanghai Jiao Tong University 200240 Shanghai CHINA
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7
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Petroff R, Hendrix A, Shum S, Grant KS, Lefebvre KA, Burbacher TM. Public health risks associated with chronic, low-level domoic acid exposure: A review of the evidence. Pharmacol Ther 2021; 227:107865. [PMID: 33930455 DOI: 10.1016/j.pharmthera.2021.107865] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 04/02/2021] [Accepted: 04/05/2021] [Indexed: 12/13/2022]
Abstract
Domoic acid (DA), the causative agent for the human syndrome Amnesic Shellfish Poisoning (ASP), is a potent, naturally occurring neurotoxin produced by common marine algae. DA accumulates in seafood, and humans and wildlife alike can subsequently be exposed when consuming DA-contaminated shellfish or finfish. While strong regulatory limits protect people from the acute effects associated with ASP, DA is an increasingly significant public health concern, particularly for coastal dwelling populations, and there is a growing body of evidence suggesting that there are significant health consequences following repeated exposures to levels of the toxin below current safety guidelines. However, gaps in scientific knowledge make it difficult to precisely determine the risks of contemporary low-level exposure scenarios. The present review characterizes the toxicokinetics and neurotoxicology of DA, discussing results from clinical and preclinical studies after both adult and developmental DA exposure. The review also highlights crucial areas for future DA research and makes the case that DA safety limits need to be reassessed to best protect public health from deleterious effects of this widespread marine toxin.
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Affiliation(s)
- Rebekah Petroff
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - Alicia Hendrix
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - Sara Shum
- Department of Pharmaceutics, University of Washington, Seattle, WA, USA
| | - Kimberly S Grant
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA; Center on Human Development and Disability, University of Washington, Seattle, WA, USA
| | - Kathi A Lefebvre
- Environmental and Fisheries Sciences Division, Northwest Fisheries Science Center, National Marine Fisheries Service, NOAA, 2725 Montlake Blvd. East, Seattle, WA, USA
| | - Thomas M Burbacher
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA; Center on Human Development and Disability, University of Washington, Seattle, WA, USA; Infant Primate Research Laboratory, Washington National Primate Research Center, Seattle,WA, USA.
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8
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Biosynthesis of marine toxins. Curr Opin Chem Biol 2020; 59:119-129. [DOI: 10.1016/j.cbpa.2020.06.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 06/21/2020] [Accepted: 06/23/2020] [Indexed: 12/18/2022]
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9
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Petroff R, Murias M, Grant KS, Crouthamel B, McKain N, Shum S, Jing J, Isoherranen N, Burbacher TM. Power spectrum analysis of EEG in a translational nonhuman primate model after chronic exposure to low levels of the common marine neurotoxin, domoic acid. Neurotoxicology 2020; 80:124-129. [PMID: 32717199 PMCID: PMC7492457 DOI: 10.1016/j.neuro.2020.07.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 07/17/2020] [Accepted: 07/18/2020] [Indexed: 11/30/2022]
Abstract
Domoic acid (DA), the focus of this research, is a marine algal neurotoxin and epileptogen produced by species in the genus Pseudo-nitzschia. DA is found in finfish and shellfish across the globe. The current regulatory limit for DA consumption (20 ppm in shellfish) was set to protect humans from acute toxic effects, but there is a growing body of evidence suggesting that regular consumption of DA contaminated seafood at or below the regulatory limit may lead to subtle neurological effects in adults. The present research uses a translational nonhuman primate model to assess neurophysiological changes after chronic exposure to DA near the regulatory limit. Sedated electroencephalography (EEG) was used in 20 healthy adult female Macaca fascicularis, orally administered 0.075 and 0.15 mg DA/kg/day for at least 10 months. Paired video and EEG recordings were cleaned and a Fast Fourier Transformation was applied to EEG recordings to assess power differences in frequency bands from 1-20 Hz. When DA exposed animals were compared to controls, power was significantly decreased in the delta band (1-4 Hz, p < 0.005) and significantly increased in the alpha band (5-8 Hz, p < 0.005), theta band (9-12 Hz, p < 0.01), and beta band (13-20 Hz, p < 0.05). The power differences were not dose dependent or related to the duration of DA exposure, or subtle clinical symptoms of DA exposure (intentional tremors). Alterations of power in these bands have been associated with a host of clinical symptoms, such as deficits in memory and neurodegenerative diseases, and ultimately provide new insight into the subclinical toxicity of chronic, low-dose DA exposure on the adult primate brain.
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Affiliation(s)
- R Petroff
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA.
| | - M Murias
- Department of Medical Social Sciences, Northwestern University, Chicago, IL, USA; Institute for Innovations in Developmental Sciences (DevSci), Northwestern University, Chicago, IL, USA
| | - K S Grant
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - B Crouthamel
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - N McKain
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - S Shum
- Department of Pharmaceutics, University of Washington, Seattle, WA, USA
| | - J Jing
- Department of Pharmaceutics, University of Washington, Seattle, WA, USA
| | - N Isoherranen
- Department of Pharmaceutics, University of Washington, Seattle, WA, USA; Center on Human Development and Disability, Seattle, WA, USA
| | - T M Burbacher
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA; Center on Human Development and Disability, Seattle, WA, USA; Infant Primate Research Laboratory, Washington National Primate Research Center, Seattle, WA, USA
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10
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Marine Excitatory Amino Acids: Structure, Properties, Biosynthesis and Recent Approaches to Their Syntheses. Molecules 2020; 25:molecules25133049. [PMID: 32635311 PMCID: PMC7412112 DOI: 10.3390/molecules25133049] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 06/30/2020] [Accepted: 07/01/2020] [Indexed: 11/26/2022] Open
Abstract
This review considers the results of recent studies on marine excitatory amino acids, including kainic acid, domoic acid, dysiherbaine, and neodysiherbaine A, known as potent agonists of one of subtypes of glutamate receptors, the so-called kainate receptors. Novel information, particularly concerning biosynthesis, environmental roles, biological action, and syntheses of these marine metabolites, obtained mainly in last 10–15 years, is summarized. The goal of the review was not only to discuss recently obtained data, but also to provide a brief introduction to the field of marine excitatory amino acid research.
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11
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Ganley JG, Derbyshire ER. Linking Genes to Molecules in Eukaryotic Sources: An Endeavor to Expand Our Biosynthetic Repertoire. Molecules 2020; 25:E625. [PMID: 32023950 PMCID: PMC7036892 DOI: 10.3390/molecules25030625] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 01/23/2020] [Accepted: 01/30/2020] [Indexed: 02/06/2023] Open
Abstract
The discovery of natural products continues to interest chemists and biologists for their utility in medicine as well as facilitating our understanding of signaling, pathogenesis, and evolution. Despite an attenuation in the discovery rate of new molecules, the current genomics and transcriptomics revolution has illuminated the untapped biosynthetic potential of many diverse organisms. Today, natural product discovery can be driven by biosynthetic gene cluster (BGC) analysis, which is capable of predicting enzymes that catalyze novel reactions and organisms that synthesize new chemical structures. This approach has been particularly effective in mining bacterial and fungal genomes where it has facilitated the discovery of new molecules, increased the understanding of metabolite assembly, and in some instances uncovered enzymes with intriguing synthetic utility. While relatively less is known about the biosynthetic potential of non-fungal eukaryotes, there is compelling evidence to suggest many encode biosynthetic enzymes that produce molecules with unique bioactivities. In this review, we highlight how the advances in genomics and transcriptomics have aided natural product discovery in sources from eukaryotic lineages. We summarize work that has successfully connected genes to previously identified molecules and how advancing these techniques can lead to genetics-guided discovery of novel chemical structures and reactions distributed throughout the tree of life. Ultimately, we discuss the advantage of increasing the known biosynthetic space to ease access to complex natural and non-natural small molecules.
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Affiliation(s)
- Jack G Ganley
- Department of Chemistry, Duke University, 124 Science Drive, Durham, NC 27708-0346, USA
| | - Emily R Derbyshire
- Department of Chemistry, Duke University, 124 Science Drive, Durham, NC 27708-0346, USA
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, 213 Research Drive, Durham, NC 27710, USA
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12
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Moyer CE, Hiolski EM, Marcinek DJ, Lefebvre KA, Smith DR, Zuo Y. Repeated low level domoic acid exposure increases CA1 VGluT1 levels, but not bouton density, VGluT2 or VGAT levels in the hippocampus of adult mice. HARMFUL ALGAE 2018; 79:74-86. [PMID: 30420019 PMCID: PMC6237202 DOI: 10.1016/j.hal.2018.08.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Domoic acid (DA) is a neurotoxin produced during harmful algal blooms that accumulates in marine organisms that serve as food resources for humans. While acute DA neurotoxicity can cause seizures and hippocampal lesions, less is known regarding how chronic, subacute DA exposure in adulthood impacts the hippocampus. With more frequent occurrences of harmful algal blooms, it is important to understand the potential impact of repeated, low-level DA exposure on human health. To model repeated, low-dose DA exposure, adult mice received a single low-dose (0.75 ± 0.05 μg/g) of DA or vehicle weekly for 22 consecutive weeks. Quantitative immunohistochemistry was performed to assess the effects of repeated, low-level DA exposure on hippocampal cells and synapses. Vesicular glutamate transporter 1 (VGluT1) immunoreactivity within excitatory boutons in CA1 of DA-exposed mice was increased. Levels of other vesicular transporter proteins (i.e., VGluT2 and the vesicular GABA transporter (VGAT)) within boutons, and corresponding bouton densities, were not significantly altered in CA1, CA3, or dentate gyrus. There were no significant changes in neuron density or glial fibrillary acidic protein (GFAP) immunoreactivity following chronic, low-dose exposure. This suggests that repeated low doses of DA, unlike high doses of DA, do not cause neuronal loss or astrocyte activation in hippocampus in adult mice. Instead, these findings demonstrate that repeated exposure to low levels of DA leads to subtle changes in VGluT1 expression within CA1 excitatory boutons, which may alter glutamatergic transmission in CA1 and disrupt behaviors dependent on spatial memory.
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Affiliation(s)
- Caitlin E Moyer
- Department of Molecular, Cell, and Developmental Biology, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA, 95064, United States
| | - Emma M Hiolski
- Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA, 95064, United States
| | - David J Marcinek
- Departments of Radiology, Pathology, and Bioengineering, University of Washington, South Lake Union Campus, 850 Republican St., Brotman 142, Box 358050, Seattle, WA, 98109, United States
| | - Kathi A Lefebvre
- Environmental and Fisheries Science Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Blvd. East, Seattle, WA 98112, United States
| | - Donald R Smith
- Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA, 95064, United States
| | - Yi Zuo
- Department of Molecular, Cell, and Developmental Biology, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA, 95064, United States.
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13
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Brunson JK, McKinnie SMK, Chekan JR, McCrow JP, Miles ZD, Bertrand EM, Bielinski VA, Luhavaya H, Oborník M, Smith GJ, Hutchins DA, Allen AE, Moore BS. Biosynthesis of the neurotoxin domoic acid in a bloom-forming diatom. Science 2018; 361:1356-1358. [PMID: 30262498 PMCID: PMC6276376 DOI: 10.1126/science.aau0382] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 08/15/2018] [Indexed: 01/26/2023]
Abstract
Oceanic harmful algal blooms of Pseudo-nitzschia diatoms produce the potent mammalian neurotoxin domoic acid (DA). Despite decades of research, the molecular basis for its biosynthesis is not known. By using growth conditions known to induce DA production in Pseudo-nitzschia multiseries, we implemented transcriptome sequencing in order to identify DA biosynthesis genes that colocalize in a genomic four-gene cluster. We biochemically investigated the recombinant DA biosynthetic enzymes and linked their mechanisms to the construction of DA's diagnostic pyrrolidine skeleton, establishing a model for DA biosynthesis. Knowledge of the genetic basis for toxin production provides an orthogonal approach to bloom monitoring and enables study of environmental factors that drive oceanic DA production.
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Affiliation(s)
- John K Brunson
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA
- Microbial and Environmental Genomics Group, J. Craig Venter Institute, La Jolla, CA 92037, USA
| | - Shaun M K McKinnie
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jonathan R Chekan
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA
| | - John P McCrow
- Microbial and Environmental Genomics Group, J. Craig Venter Institute, La Jolla, CA 92037, USA
| | - Zachary D Miles
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA
| | - Erin M Bertrand
- Microbial and Environmental Genomics Group, J. Craig Venter Institute, La Jolla, CA 92037, USA
- Department of Biology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Vincent A Bielinski
- Synthetic Biology and Bioenergy Group, J. Craig Venter Institute, La Jolla, CA 92037, USA
| | - Hanna Luhavaya
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA
| | - Miroslav Oborník
- Institute of Parasitology, University of South Bohemia and Biology Center CAS, Branišovská 31, 370 05 České Budějovice, Czech Republic
| | - G Jason Smith
- Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, CA 95039, USA
| | - David A Hutchins
- Marine and Environmental Biology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Andrew E Allen
- Microbial and Environmental Genomics Group, J. Craig Venter Institute, La Jolla, CA 92037, USA.
- Integrative Oceanography Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92037, USA
| | - Bradley S Moore
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA.
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093, USA
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Demars F, Clark K, Wyeth MS, Abrams E, Buckmaster PS. A single subconvulsant dose of domoic acid at mid-gestation does not cause temporal lobe epilepsy in mice. Neurotoxicology 2018; 66:128-137. [PMID: 29625197 PMCID: PMC5940543 DOI: 10.1016/j.neuro.2018.04.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 03/28/2018] [Accepted: 04/02/2018] [Indexed: 11/19/2022]
Abstract
Harmful blooms of domoic acid (DA)-producing algae are a problem in oceans worldwide. DA is a potent glutamate receptor agonist that can cause status epilepticus and in survivors, temporal lobe epilepsy. In mice, one-time low-dose in utero exposure to DA was reported to cause hippocampal damage and epileptiform activity, leading to the hypothesis that unrecognized exposure to DA from contaminated seafood in pregnant women can damage the fetal hippocampus and initiate temporal lobe epileptogenesis. However, development of epilepsy (i.e., spontaneous recurrent seizures) has not been tested. In the present study, long-term seizure monitoring and histology was used to test for temporal lobe epilepsy following prenatal exposure to DA. In Experiment One, the previous study's in utero DA treatment protocol was replicated, including use of the CD-1 mouse strain. Afterward, mice were video-monitored for convulsive seizures from 2 to 6 months old. None of the CD-1 mice treated in utero with vehicle or DA was observed to experience spontaneous convulsive seizures. After seizure monitoring, mice were evaluated for pathological evidence of temporal lobe epilepsy. None of the mice treated in utero with DA displayed the hilar neuron loss that occurs in patients with temporal lobe epilepsy and in the mouse pilocarpine model of temporal lobe epilepsy. In Experiment Two, a higher dose of DA was administered to pregnant FVB mice. FVB mice were tested as a potentially more sensitive strain, because they have a lower seizure threshold, and some females spontaneously develop epilepsy. Female offspring were monitored with continuous video and telemetric bilateral hippocampal local field potential recording at 1-11 months old. A similar proportion of vehicle- and DA-treated female FVB mice spontaneously developed epilepsy, beginning in the fourth month of life. Average seizure frequency and duration were similar in both groups. Seizure frequency was lower than that of positive-control pilocarpine-treated mice, but seizure duration was similar. None of the mice treated in utero with vehicle or DA displayed hilar neuron loss or intense mossy fiber sprouting, a form of aberrant synaptic reorganization that develops in patients with temporal lobe epilepsy and in pilocarpine-treated mice. FVB mice that developed epilepsy (vehicle- and DA-treated) displayed mild mossy fiber sprouting. Results of this study suggest that a single subconvulsive dose of DA at mid-gestation does not cause temporal lobe epilepsy in mice.
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Affiliation(s)
- Fanny Demars
- Department of Comparative Medicine, School of Medicine, Stanford University, Stanford, CA, United States; VetAgro Sup, School of Veterinary Medicine, Lyon, France; Paris Descartes University, Paris, France
| | - Kristen Clark
- Department of Comparative Medicine, School of Medicine, Stanford University, Stanford, CA, United States; College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, United States
| | - Megan S Wyeth
- Department of Comparative Medicine, School of Medicine, Stanford University, Stanford, CA, United States
| | - Emily Abrams
- Department of Comparative Medicine, School of Medicine, Stanford University, Stanford, CA, United States
| | - Paul S Buckmaster
- Department of Comparative Medicine, School of Medicine, Stanford University, Stanford, CA, United States; Department of Neurology & Neurological Sciences, School of Medicine, Stanford University, Stanford, CA, United States.
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15
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The Molecular Basis of Toxins' Interactions with Intracellular Signaling via Discrete Portals. Toxins (Basel) 2017; 9:toxins9030107. [PMID: 28300784 PMCID: PMC5371862 DOI: 10.3390/toxins9030107] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 03/02/2017] [Accepted: 03/04/2017] [Indexed: 12/20/2022] Open
Abstract
An understanding of the molecular mechanisms by which microbial, plant or animal-secreted toxins exert their action provides the most important element for assessment of human health risks and opens new insights into therapies addressing a plethora of pathologies, ranging from neurological disorders to cancer, using toxinomimetic agents. Recently, molecular and cellular biology dissecting tools have provided a wealth of information on the action of these diverse toxins, yet, an integrated framework to explain their selective toxicity is still lacking. In this review, specific examples of different toxins are emphasized to illustrate the fundamental mechanisms of toxicity at different biochemical, molecular and cellular- levels with particular consideration for the nervous system. The target of primary action has been highlighted and operationally classified into 13 sub-categories. Selected examples of toxins were assigned to each target category, denominated as portal, and the modulation of the different portal’s signaling was featured. The first portal encompasses the plasma membrane lipid domains, which give rise to pores when challenged for example with pardaxin, a fish toxin, or is subject to degradation when enzymes of lipid metabolism such as phospholipases A2 (PLA2) or phospholipase C (PLC) act upon it. Several major portals consist of ion channels, pumps, transporters and ligand gated ionotropic receptors which many toxins act on, disturbing the intracellular ion homeostasis. Another group of portals consists of G-protein-coupled and tyrosine kinase receptors that, upon interaction with discrete toxins, alter second messengers towards pathological levels. Lastly, subcellular organelles such as mitochondria, nucleus, protein- and RNA-synthesis machineries, cytoskeletal networks and exocytic vesicles are also portals targeted and deregulated by other diverse group of toxins. A fundamental concept can be drawn from these seemingly different toxins with respect to the site of action and the secondary messengers and signaling cascades they trigger in the host. While the interaction with the initial portal is largely determined by the chemical nature of the toxin, once inside the cell, several ubiquitous second messengers and protein kinases/ phosphatases pathways are impaired, to attain toxicity. Therefore, toxins represent one of the most promising natural molecules for developing novel therapeutics that selectively target the major cellular portals involved in human physiology and diseases.
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Hiolski EM, Ito S, Beggs JM, Lefebvre KA, Litke AM, Smith DR. Domoic acid disrupts the activity and connectivity of neuronal networks in organotypic brain slice cultures. Neurotoxicology 2016; 56:215-224. [PMID: 27506300 DOI: 10.1016/j.neuro.2016.08.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 08/04/2016] [Accepted: 08/05/2016] [Indexed: 12/22/2022]
Abstract
Domoic acid is a neurotoxin produced by algae and is found in seafood during harmful algal blooms. As a glutamate agonist, domoic acid inappropriately stimulates excitatory activity in neurons. At high doses, this leads to seizures and brain lesions, but it is unclear how lower, asymptomatic exposures disrupt neuronal activity. Domoic acid has been detected in an increasing variety of species across a greater geographical range than ever before, making it critical to understand the potential health impacts of low-level exposure on vulnerable marine mammal and human populations. To determine whether prolonged domoic acid exposure altered neuronal activity in hippocampal networks, we used a custom-made 512 multi-electrode array with high spatial and temporal resolution to record extracellular potentials (spikes) in mouse organotypic brain slice cultures. We identified individual neurons based on spike waveform and location, and measured the activity and functional connectivity within the neuronal networks of brain slice cultures. Domoic acid exposure significantly altered neuronal spiking activity patterns, and increased functional connectivity within exposed cultures, in the absence of overt cellular or neuronal toxicity. While the overall spiking activity of neurons in domoic acid-exposed cultures was comparable to controls, exposed neurons spiked significantly more often in bursts. We also identified a subset of neurons that were electrophysiologically silenced in exposed cultures, and putatively identified those neurons as fast-spiking inhibitory neurons. These results provide evidence that domoic acid affects neuronal activity in the absence of cytotoxicity, and suggest that neurodevelopmental exposure to domoic acid may alter neurological function in the absence of clinical symptoms.
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Affiliation(s)
- E M Hiolski
- Department of Microbiology & Environmental Toxicology, University of California, Santa Cruz, CA, USA
| | - S Ito
- Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, CA, USA
| | - J M Beggs
- Department of Physics, Indiana University, Bloomington, IN, USA
| | - K A Lefebvre
- Northwest Fisheries Science Center, NOAA Fisheries, Seattle, WA, USA
| | - A M Litke
- Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, CA, USA
| | - D R Smith
- Department of Microbiology & Environmental Toxicology, University of California, Santa Cruz, CA, USA
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Zabaglo K, Chrapusta E, Bober B, Kaminski A, Adamski M, Bialczyk J. Environmental roles and biological activity of domoic acid: A review. ALGAL RES 2016. [DOI: 10.1016/j.algal.2015.11.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Vieira AC, Alemañ N, Cifuentes JM, Bermúdez R, Peña ML, Botana LM. Brain Pathology in Adult Rats Treated With Domoic Acid. Vet Pathol 2015; 52:1077-86. [DOI: 10.1177/0300985815584074] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Domoic acid (DA) is a neurotoxin reported to produce damage to the hippocampus, which plays an important role in memory. The authors inoculated rats intraperitoneally with an effective toxic dose of DA to study the distribution of the toxin in major internal organs by using immunohistochemistry, as well as to evaluate the induced pathology by means of histopathologic and immunohistochemical methods at different time points after toxin administration (6, 10, and 24 hours; 5 and 54 days). DA was detected by immunohistochemistry exclusively in pyramidal neurons of the hippocampus at 6 and 10 hours after dosing. Lesions induced by DA were prominent at 5 days following treatment in selected regions of the brain: hippocampus, amygdala, piriform and perirhinal cortices, olfactory tubercle, septal nuclei, and thalamus. The authors found 2 types of lesions: delayed death of selective neurons and large areas of necrosis, both accompanied by astrocytosis and microgliosis. At 54 days after DA exposure, the pathology was characterized by still-distinguishable dying neurons, calcified lesions in the thalamus, persistent astrocytosis, and pronounced microgliosis. The expression of nitric oxide synthases suggests a role for nitric oxide in the pathogenesis of neuronal degeneration and chronic inflammation induced by DA in the brain.
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Affiliation(s)
- A. C. Vieira
- Departamento de Farmacología, Facultad de Veterinaria, Lugo, Spain
| | - N. Alemañ
- Anatomía y Producción Animal, Facultad de Veterinaria, Lugo, Spain
| | - J. M. Cifuentes
- Anatomía y Producción Animal, Facultad de Veterinaria, Lugo, Spain
| | - R. Bermúdez
- Anatomía y Producción Animal, Facultad de Veterinaria, Lugo, Spain
| | - M. López Peña
- Ciencias Clínicas Veterinarias, Facultad de Veterinaria, Lugo, Spain
| | - L. M. Botana
- Departamento de Farmacología, Facultad de Veterinaria, Lugo, Spain
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JANDOVÁ K, KOZLER P, LANGMEIER M, MAREŠOVÁ D, POKORNÝ J, RILJAK V. Influence of Low-Dose Neonatal Domoic Acid on the Spontaneous Behavior of Rats in Early Adulthood. Physiol Res 2014; 63:S521-8. [DOI: 10.33549/physiolres.932936] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Consumption of seafood containing toxin domoic acid (DA) causes an alteration of glutamatergic signaling pathways and could lead to various signs of neurotoxicity in animals and humans. Neonatal treatment with domoic acid was suggested as valuable model of schizophrenia and epilepsy. We tested how repeated early postnatal DA administration influences the spontaneous behavior of rats in adulthood. Rats were injected with 30 μg DA/kg from postnatal day (PND) 10 until PND 14. Their behavior was observed in the open field test for one hour (Laboras, Metris) at PND 35, PND 42 and PND 112. We did not find any difference between DA treated rats and animals injected with equivalent volume of saline in both test sessions at PND 35 and PND 42. DA rats at PND 112 exhibited significantly higher vertical and horizontal exploratory activity (tested parameters: locomotion, distance travelled, average speed reached during test, grooming and rearing) between the 30th-40th min of the test session and habituated over 10 min later. We conclude that at least in the given experimental design, neonatal DA treatment results in alteration of the spontaneous behavior of rats in adulthood.
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Affiliation(s)
- K. JANDOVÁ
- Institute of Physiology, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic
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Buckmaster PS, Wen X, Toyoda I, Gulland FMD, Van Bonn W. Hippocampal neuropathology of domoic acid-induced epilepsy in California sea lions (Zalophus californianus). J Comp Neurol 2014; 522:1691-706. [PMID: 24638960 DOI: 10.1002/cne.23509] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 11/21/2013] [Accepted: 11/21/2013] [Indexed: 12/24/2022]
Abstract
California sea lions (Zalophus californianus) are abundant human-sized carnivores with large gyrencephalic brains. They develop epilepsy after experiencing status epilepticus when naturally exposed to domoic acid. We tested whether sea lions previously exposed to DA (chronic DA sea lions) display hippocampal neuropathology similar to that of human patients with temporal lobe epilepsy. Hippocampi were obtained from control and chronic DA sea lions. Stereology was used to estimate numbers of Nissl-stained neurons per hippocampus in the granule cell layer, hilus, and pyramidal cell layer of CA3, CA2, and CA1 subfields. Adjacent sections were processed for somatostatin immunoreactivity or Timm-stained, and the extent of mossy fiber sprouting was measured stereologically. Chronic DA sea lions displayed hippocampal neuron loss in patterns and extents similar but not identical to those reported previously for human patients with temporal lobe epilepsy. Similar to human patients, hippocampal sclerosis in sea lions was unilateral in 79% of cases, mossy fiber sprouting was a common neuropathological abnormality, and somatostatin-immunoreactive axons were exuberant in the dentate gyrus despite loss of immunopositive hilar neurons. Thus, hippocampal neuropathology of chronic DA sea lions is similar to that of human patients with temporal lobe epilepsy.
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Affiliation(s)
- Paul S Buckmaster
- Department of Comparative Medicine, Stanford University, Stanford, California, 94305; Department of Neurology & Neurological Sciences, Stanford University, Stanford, California, 94305
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SCHWARZ M, JANDOVÁ K, STRUK I, MAREŠOVÁ D, POKORNÝ J, RILJAK V. Low Dose Domoic Acid Influences Spontaneous Behavior in Adult Rats. Physiol Res 2014; 63:369-76. [DOI: 10.33549/physiolres.932636] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Domoic acid (DA) is a potent marine neurotoxine present in seafood. Intoxication by DA causes gastrointestinal symptoms like vomiting and diarrhoea and also the so-called amnesic shellfish poisoning (inflicting memory impairment and seizures). Since exposure to non-convulsive doses is relevant to the human health, we investigated the effect of low dose DA administration in adult Wistar rats. Rats were administered with DA at the dose 1.0 mg/kg and their behavior was monitored for one hour in three sessions. The first session started immediately after DA administration. The second and third session started one and two weeks later. After the third session, the histochemical analysis of the hippocampi of the animals was conducted (Fluoro-Jade B, bis-benzimide). DA increased time spent by locomotion and distance travelled in the second half of the first session and this effect was pronounced during the second and third session. Exploratory rearing was decreased by DA administration in the first half of the first session. DA influenced the grooming in biphasic manner (decrease followed by an increase of time spent by grooming). This biphasic trend was observed even two weeks after the DA administration. Histochemistry of DA treated rats did not confirm the presence of apoptotic bodies, Fluoro-Jade B positive cells were not found neither in CA1 nor CA3 area of the hippocampi. Our study revealed that a low dose of DA affect short and long-term the spontaneous behavior of rats without inducing neuronal damage.
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Affiliation(s)
| | | | | | | | | | - V. RILJAK
- Institute of Physiology, First Faculty of Medicine, Charles University in Prague, Czech Republic
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22
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Nicolas J, Hendriksen PJM, Gerssen A, Bovee TFH, Rietjens IMCM. Marine neurotoxins: State of the art, bottlenecks, and perspectives for mode of action based methods of detection in seafood. Mol Nutr Food Res 2013; 58:87-100. [DOI: 10.1002/mnfr.201300520] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 10/16/2013] [Accepted: 10/19/2013] [Indexed: 01/21/2023]
Affiliation(s)
- Jonathan Nicolas
- Division of Toxicology; Wageningen University; Wageningen The Netherlands
- RIKILT; Institute of Food Safety; Wageningen The Netherlands
| | | | - Arjen Gerssen
- RIKILT; Institute of Food Safety; Wageningen The Netherlands
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23
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Baron AW, Rushton SP, Rens N, Morris CM, Blain PG, Judge SJ. Sex differences in effects of low level domoic acid exposure. Neurotoxicology 2013; 34:1-8. [PMID: 23099319 DOI: 10.1016/j.neuro.2012.10.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 10/04/2012] [Accepted: 10/15/2012] [Indexed: 11/18/2022]
Abstract
Consumption of seafood containing the phytoplankton-derived toxin domoic acid (DOM) causes neurotoxicity in humans and in animals. It has been reported that DOM-induced symptoms may be more severe in men than women, but to date the effect of sex on DOM-induced effects in adults is not known. We investigated sex differences in DOM-induced effects in adult rats. Since low level exposure is of greatest relevance to human health (due to DOM regulatory limit), we examined the effects of low level exposure. Adult male and female Sprague Dawley rats were administered a single intraperitoneal injection of DOM (0, 1.0, 1.8 mg/kg). Behaviour was monitored for 3h and immunohistochemistry in the dorsal hippocampus and olfactory bulb was also examined. DOM increased locomotor and grooming activity, compared to vehicle group. DOM exposure also significantly increased stereotypic behaviours and decreased phosphorylated cAMP response element-binding protein immunoreactivity (pCREB-IR). There was no effect of sex on the magnitude of the behavioural responses, but the onset of DOM-induced locomotor activity and ear scratches was quicker in females than in males. Mixed effect modelling revealed the predicted peak in locomotor activity in response to DOM was also quicker in females than in males. Severe toxicity was evident in 2/7 male rats and 0/8 female rats dosed with 1.8 mg/kg DOM. These data suggest that males exposed to low level DOM may be more susceptible to severe neurotoxicity, whereas females are affected more quickly. Understanding sex differences in DOM-induced neurotoxicity may contribute to future protective strategies and treatments.
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Affiliation(s)
- Andrew W Baron
- Medical Toxicology Centre, Newcastle University, Newcastle upon Tyne NE2 4AA, UK.
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24
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Martin LJ. An approach to experimental synaptic pathology using green fluorescent protein-transgenic mice and gene knockout mice to show mitochondrial permeability transition pore-driven excitotoxicity in interneurons and motoneurons. Toxicol Pathol 2011; 39:220-33. [PMID: 21378209 PMCID: PMC3517994 DOI: 10.1177/0192623310389475] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Researchers used transgenic mice expressing enhanced-green fluorescent protein (eGFP) driven by either the glycine transporter-2 gene promoter to specifically visualize glycinergic interneurons or the homeobox-9 (Hb9) gene promoter to visualize motoneurons for assessing their vulnerabilities to excitotoxins in vivo. Stereotaxic excitotoxic lesions were made in adult male and female mouse lumbar spinal cord with the specific N-methyl-D-aspartate (NMDA) receptor agonist quinolinic acid (QA) and the non-NMDA ion channel glutamate receptor agonist kainic acid (KA). QA and KA induced large-scale degeneration of glycinergic interneurons in spinal cord. Glycinergic interneurons were more sensitive than motoneurons to NMDA receptor-mediated and non-NMDA glutamate receptor-mediated excitotoxicity. Outcome after spinal cord excitotoxicity was gender-dependent, with males showing greater sensitivity than females. Excitotoxic degeneration of spinal interneurons resembled apoptosis, while motoneuron degeneration appeared non-apoptotic. Perikaryal mitochondrial accumulation was antecedent to both NMDA and non-NMDA receptor-mediated excitotoxic stimulation of interneurons and motoneurons. Genetic ablation of cyclophilin D, a regulator of the mitochondrial permeability transition pore (mPTP), protected both interneurons and motoneurons from excitotoxicity. The results demonstrate in adult mouse spinal cord that glycinergic interneurons are more sensitive than motoneurons to excitotoxicity that stimulates mitochondrial accumulation, and that the mPTP has pro-death functions mediating apoptotic and non-apoptotic neuronal degeneration in vivo.
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Affiliation(s)
- Lee J Martin
- Department of Pathology, 558 Ross Building, 720 Rutland Avenue, Baltimore, MD 21205-2196, USA.
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25
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Bargu S, Smith E, Ozhan K. Toxic Diatom Pseudo-nitzschia and Its Primary Consumers (Vectors). THE DIATOM WORLD 2011. [DOI: 10.1007/978-94-007-1327-7_22] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Nogueira I, Lobo-da-Cunha A, Afonso A, Rivera S, Azevedo J, Monteiro R, Cervantes R, Gago-Martinez A, Vasconcelos V. Toxic effects of domoic acid in the seabream Sparus aurata. Mar Drugs 2010; 8:2721-32. [PMID: 21116416 PMCID: PMC2993002 DOI: 10.3390/md8102721] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Revised: 10/07/2010] [Accepted: 10/14/2010] [Indexed: 11/16/2022] Open
Abstract
Neurotoxicity induced in fish by domoic acid (DA) was assessed with respect to occurrence of neurotoxic signs, lethality, and histopathology by light microscopy. Sparus aurata were exposed to a single dose of DA by intraperitoneal (i.p.) injection of 0, 0.45, 0.9, and 9.0 mg DA kg(-1) bw. Mortality (66.67 ± 16.67%) was only observed in dose of 9.0 mg kg(-1) bw. Signs of neurological toxicity were detected for the doses of 0.9 and 9.0 mg DA kg(-1) bw. Furthermore, the mean concentrations (±SD) of DA detected by HPLC-UV in extracts of brain after exposure to 9.0 mg DA kg(-1) bw were 0.61 ± 0.01, 0.96 ± 0.00, and 0.36 ± 0.01 mg DA kg(-1) tissue at 1, 2, and 4 hours. The lack of major permanent brain damage in S. aurata, and reversibility of neurotoxic signs, suggest that lower susceptibility to DA or neuronal recovery occurs in affected individuals.
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Affiliation(s)
- Isabel Nogueira
- CIIMAR/CIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Rua dos Bragas 177-289, 4150-123 Porto, Portugal; E-Mails: (I.N.); (A.A.); (J.A.)
| | - Alexandre Lobo-da-Cunha
- CIIMAR/CIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Rua dos Bragas 177-289, 4150-123 Porto, Portugal; E-Mails: (I.N.); (A.A.); (J.A.)
- Laboratório de Biologia Celular, Instituto de Ciências Biomédicas Abel Salazar, ICBAS, Lg. Abel Salazar 2, 4099-003 Porto, Portugal; E-Mail: (A.L.C.)
| | - António Afonso
- CIIMAR/CIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Rua dos Bragas 177-289, 4150-123 Porto, Portugal; E-Mails: (I.N.); (A.A.); (J.A.)
| | - Socorro Rivera
- Departamento de Química Analítica, Facultad de Química, As Lagoas Marcosende C.P. 36210, Spain; E-Mails: (S.R.); (A.G.-M.)
| | - Joana Azevedo
- CIIMAR/CIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Rua dos Bragas 177-289, 4150-123 Porto, Portugal; E-Mails: (I.N.); (A.A.); (J.A.)
| | - Rogério Monteiro
- CIIMAR/CIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Rua dos Bragas 177-289, 4150-123 Porto, Portugal; E-Mails: (I.N.); (A.A.); (J.A.)
- Laboratório de Histologia e Embriologia, Instituto de Ciências Biomédicas Abel Salazar, ICBAS, Lg. Abel Salazar 2, 4099-003 Porto, Portugal; E-Mail: (R.M.)
| | - Rosa Cervantes
- Departamento de Química Analítica, Facultad de Química, As Lagoas Marcosende C.P. 36210, Spain; E-Mails: (S.R.); (A.G.-M.)
| | - Ana Gago-Martinez
- Departamento de Química Analítica, Facultad de Química, As Lagoas Marcosende C.P. 36210, Spain; E-Mails: (S.R.); (A.G.-M.)
| | - Vítor Vasconcelos
- CIIMAR/CIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Rua dos Bragas 177-289, 4150-123 Porto, Portugal; E-Mails: (I.N.); (A.A.); (J.A.)
- Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre 4169-007 Porto, Portugal
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Costa LG, Giordano G, Faustman EM. Domoic acid as a developmental neurotoxin. Neurotoxicology 2010; 31:409-23. [PMID: 20471419 PMCID: PMC2934754 DOI: 10.1016/j.neuro.2010.05.003] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Revised: 05/04/2010] [Accepted: 05/05/2010] [Indexed: 11/21/2022]
Abstract
Domoic acid (DomA) is an excitatory amino acid which can accumulate in shellfish and finfish under certain environmental conditions. DomA is a potent neurotoxin. In humans and in non-human primates, oral exposure to a few mg/kg DomA elicits gastrointestinal effects, while slightly higher doses cause neurological symptoms, seizures, memory impairment, and limbic system degeneration. In rodents, which appear to be less sensitive than humans or non-human primates, oral doses cause behavioral abnormalities (e.g. hindlimb scratching), followed by seizures and hippocampal degeneration. Similar effects are also seen in other species (from sea lions to zebrafish), indicating that DomA exerts similar neurotoxic effects across species. The neurotoxicity of DomA is ascribed to its ability to interact and activate the AMPA/KA receptors, a subfamily of receptors for the neuroexcitatory neurotransmitter glutamate. Studies exploring the neurotoxic effects of DomA on the developing nervous system indicate that DomA elicits similar behavioral, biochemical and morphological effects as in adult animals. However, most importantly, developmental neurotoxicity is seen at doses of DomA that are one to two orders of magnitude lower than those exerting neurotoxicity in adults. This difference may be due to toxicokinetic and/or toxicodynamic differences. Estimated safe doses may be exceeded in adults by high consumption of shellfish contaminated with DomA at the current limit of 20 microg/g. Given the potential higher susceptibility of the young to DomA neurotoxicity, additional studies investigating exposure to, and effects of this neurotoxin during brain development are warranted.
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Affiliation(s)
- Lucio G Costa
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98105, USA.
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Domoic acid toxicologic pathology: a review. Mar Drugs 2008; 6:180-219. [PMID: 18728725 PMCID: PMC2525487 DOI: 10.3390/md20080010] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2007] [Revised: 05/16/2008] [Accepted: 05/16/2008] [Indexed: 12/29/2022] Open
Abstract
Domoic acid was identified as the toxin responsible for an outbreak of human poisoning that occurred in Canada in 1987 following consumption of contaminated blue mussels [Mytilus edulis]. The poisoning was characterized by a constellation of clinical symptoms and signs. Among the most prominent features described was memory impairment which led to the name Amnesic Shellfish Poisoning [ASP]. Domoic acid is produced by certain marine organisms, such as the red alga Chondria armata and planktonic diatom of the genus Pseudo-nitzschia. Since 1987, monitoring programs have been successful in preventing other human incidents of ASP. However, there are documented cases of domoic acid intoxication in wild animals and outbreaks of coastal water contamination in many regions world-wide. Hence domoic acid continues to pose a global risk to the health and safety of humans and wildlife. Several mechanisms have been implicated as mediators for the effects of domoic acid. Of particular importance is the role played by glutamate receptors as mediators of excitatory neurotransmission and the demonstration of a wide distribution of these receptors outside the central nervous system, prompting the attention to other tissues as potential target sites. The aim of this document is to provide a comprehensive review of ASP, DOM induced pathology including ultrastructural changes associated to subchronic oral exposure, and discussion of key proposed mechanisms of cell/tissue injury involved in DOM induced brain pathology and considerations relevant to food safety and human health.
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Hesp BR, Clarkson AN, Sawant PM, Kerr DS. Domoic acid preconditioning and seizure induction in young and aged rats. Epilepsy Res 2007; 76:103-12. [PMID: 17716870 DOI: 10.1016/j.eplepsyres.2007.07.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 05/21/2007] [Accepted: 07/10/2007] [Indexed: 11/28/2022]
Abstract
Clinical reports suggest that the elderly are hypersensitive to the neurological effects of domoic acid (DOM). In the present study we assessed DOM-induced seizures in young and aged rats, and seizure attenuation following low-dose DOM pretreatment (i.e. preconditioning). Seizure behaviours following saline or DOM administration (0.5-2mg/kg i.p.) were continuously monitored for 2.5h in naïve and DOM preconditioned rats. Competitive ELISA was used to determine serum and brain DOM concentrations. Dose- and age-dependent increases in seizure activity were evident in response to DOM. Lower doses of DOM in young and aged rats promoted low level seizure behaviours. Animals administered high doses (2mg/kg in young; 1mg/kg in aged) progressed through various stages of stereotypical behaviour (e.g., head tics, scratching, wet dog shakes) before ultimately exhibiting tonic-clonic convulsions. Serum and brain DOM analysis indicated impaired renal clearance as contributory to increased DOM sensitivity in aged animals, and this was supported by seizure analysis following direct intrahippocampal administration of DOM. Preconditioning young and aged animals with low-dose DOM 45-90 min before high-dose DOM significantly reduced seizure intensity. We conclude that age-related supersensitivity to DOM is related to reduced clearance rather than increased neuronal sensitivity, and that preconditioning mechanisms underlying an inducible tolerance to excitotoxins are robustly expressed in both young and aged CNS.
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Affiliation(s)
- Blair R Hesp
- Department of Pharmacology & Toxicology, University of Otago School of Medical Sciences, Dunedin, New Zealand
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Karangwa C, Esters V, Tits M, Minet A, Boland A, Seutin V, Noirfalise A, Angenot L, Grisar T, Foidart A. Characterization of the neurotoxicity induced by the extract of Magnistipula butayei (Chrysobalanaceae) in rat: Effects of a new natural convulsive agent. Toxicon 2007; 49:1109-19. [PMID: 17395230 DOI: 10.1016/j.toxicon.2007.02.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Revised: 01/30/2007] [Accepted: 02/01/2007] [Indexed: 11/24/2022]
Abstract
This study was designed to document convulsant and neurotoxic properties of extracts of a tropical tree, Magnistipula butayei subsp. Montana, and to investigate the involvement of the glutamatergic system in these effects. Continuous behavioral observations and electroencephalographic (EEG) records were obtained after per os administration of an aqueous extract of Magnistipula (MBMAE) in rats. MBMAE (800 mg/kg) induced behavioral changes resembling motor limbic seizures: staring and head tremor, automatisms, forelimb clonic movements and violent tonic-clonic seizures leading to death in all animals. Concomitantly, important seizure activity that gradually evolved to epileptiform activity was recorded on the EEG. Moreover, c-Fos immunohistochemistry has revealed an increased c-Fos expression in the dentate gyrus and in piriform, peri- and entorhinal cortices 2 and 4h after treatment. This expression pattern suggested that the mechanism of action for the MBMAE is similar to that observed in glutamate-induced models of epilepsy. The MBMAE increased cell death also in hippocampal cell cultures. Furthermore, the build-up of convulsive activity and epileptic discharges induced by MBMAE in rat were abolished by MK-801, an NMDA receptor antagonist. Our study suggests that MBMAE contains a potent toxin, with a powerful neurotoxic activity in rat, and corresponding to a new natural component(s) that act as an NMDA-mediated convulsant molecule.
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Affiliation(s)
- Charles Karangwa
- Natural and Synthetic Drugs Research Center (CPSNS), University of Liege, B-4000 Liege, Belgium
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Giordano G, White CC, McConnachie LA, Fernandez C, Kavanagh TJ, Costa LG. Neurotoxicity of domoic Acid in cerebellar granule neurons in a genetic model of glutathione deficiency. Mol Pharmacol 2006; 70:2116-26. [PMID: 17000861 DOI: 10.1124/mol.106.027748] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
This study investigated the role of cellular antioxidant defense mechanisms in modulating the neurotoxicity of domoic acid (DomA), by using cerebellar granule neurons (CGNs) from mice lacking the modifier subunit of glutamate-cysteine ligase (Gclm). Glutamate-cysteine ligase (Glc) catalyzes the first and rate-limiting step in glutathione (GSH) biosynthesis. CGNs from Gclm (-/-) mice have very low levels of GSH and are 10-fold more sensitive to DomA-induced toxicity than CGNs from Gclm (+/+) mice. GSH ethyl ester decreased, whereas the Gcl inhibitor buthionine sulfoximine increased DomA toxicity. Antagonists of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/kainate receptors and of N-methyl-D-aspartate (NMDA) receptors blocked DomA toxicity, and NMDA receptors were activated by DomA-induced l-glutamate release. The differential susceptibility of CGNs to DomA toxicity was not due to a differential expression of ionotropic glutamate receptors, as evidenced by similar calcium responses and L-glutamate release in the two genotypes. A calcium chelator and several antioxidants antagonized DomA-induced toxicity. DomA caused a rapid decrease in cellular GSH, which preceded toxicity, and the decrease was primarily due to DomA-induced GSH efflux. DomA also caused an increase in oxidative stress as indicated by increases in reactive oxygen species and lipid peroxidation, which was subsequent to GSH efflux. Astrocytes from both genotypes were resistant to DomA toxicity and presented a diminished calcium response to DomA and a lack of DomA-induced L-glutamate release. Because polymorphisms in the GCLM gene in humans are associated with low GSH levels, such individuals, as well as others with genetic conditions or environmental exposures that lead to GSH deficiency, may be more susceptible to DomA-induced neurotoxicity.
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Affiliation(s)
- G Giordano
- Department of Environmental and Occupational Health Sciences, University of Washington, 4225 Roosevelt Way NE, Suite 100, Seattle, WA 98105, USA
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33
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Leira FJ, Vieites JM, Botana LM, Vyeites MR. Domoic Acid Levels of Naturally Contaminated Scallops as Affected by Canning. J Food Sci 2006. [DOI: 10.1111/j.1365-2621.1998.tb15859.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
The term toxin refers in a specific way to a toxic substance of biologic origin; that is, a true toxin is a poison produced by a living organism. The purpose of this article is to review some of the most potentially dangerous toxins of concern today. Mechanisms of action, routes of exposure, diagnostic tools, and treatment recommendations are addressed. In addition, current therapeutic uses for certain toxins are discussed.
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Affiliation(s)
- Matthew Salzman
- Department of Emergency Medicine, Drexel University College of Medicine, 2900 W. Queen Lane, Philadelphia, PA 19129, USA
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35
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Qiu S, Currás-Collazo MC. Histopathological and molecular changes produced by hippocampal microinjection of domoic acid. Neurotoxicol Teratol 2006; 28:354-62. [PMID: 16529907 DOI: 10.1016/j.ntt.2006.01.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2005] [Revised: 01/03/2006] [Accepted: 01/26/2006] [Indexed: 11/19/2022]
Abstract
The phytoplankton-derived neurotoxin, domoic acid (DOM), frequently causes poisoning of marine animals and poses an increasing threat to public health through contamination of seafood. In this study, we used stereotactic microinjection technique to administer varying amounts of DOM into the hippocampal CA1 region in order to examine potential histopathological changes after injection of sub-lethal concentrations to CA1 pyramidal neurons. Gross anatomical abnormalities in CA1 were observed at above 10 microM DOM (3 pmol in 0.3 microl saline). At 1mM concentration, DOM produces both ipsilateral and contralateral neuronal cell death in CA1, CA3 as well as dentate gyrus subfields. Animal behavioral changes after microinjection were similar to those observed by previous studies through systemic DOM injection. Neuronal degeneration was paralleled by reduced glutamate receptor (NR1, GluR1 and GluR6/7) immunolabeling throughout the whole hippocampal formation. Pre-injection of the AMPA/KA receptor antagonist NBQX (10 microM, 0.3 microl) blocked 1mM DOM-induced neuronal degeneration as well as behavioral symptoms. At concentrations lower than 10 microM, no histopathological changes were observed microscopically, nor were the levels of immunostaining of NR1, GluR1, GluR6/7 different. However, increased immunolabeling of autophosphorylated calcium-calmodulin-dependent kinase II (CaMKII, p-Thr286) and phosphorylated cAMP response element binding protein (CREB, p-Ser133) were observed at 24 h post-injection, suggesting that altered intracellular signal transduction mediated by GluRs might be an adaptive cellular protective mechanism against DOM-induced neurotoxicity.
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Affiliation(s)
- Shenfeng Qiu
- Environmental Toxicology Graduate Program, University of California, Riverside, USA.
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36
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Qiu S, Pak CW, Currás-Collazo MC. Sequential involvement of distinct glutamate receptors in domoic acid-induced neurotoxicity in rat mixed cortical cultures: effect of multiple dose/duration paradigms, chronological age, and repeated exposure. Toxicol Sci 2005; 89:243-56. [PMID: 16221958 DOI: 10.1093/toxsci/kfj008] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The increasing occurrence of poisoning accidents in marine animals caused by the amnesic shellfish toxin, domoic acid (DOM), necessitates a better understanding of the factors contributing to DOM neurotoxicity. Here we evaluated the contribution and temporal involvement of NMDA, non-NMDA- and metabotropic-type glutamate receptors (GluRs) in DOM-induced neuronal death using rat primary mixed cortical cultures. Co-application of antagonists for AMPA/kainate- (NBQX) and NMDA-type GluRs (D-AP5) but not for metabotropic GluRs reduced DOM toxicity induced by either of three EC50 dose/duration exposure paradigms. Maximal protection offered by D-AP5 and NBQX either extended or not to the 30- to 60-min period after DOM exposure, respectively. Antagonists were ineffective if applied with a 2-h delay, indicating the presence of a critical time window for neuronal protection after DOM exposure. Early effects correlated with neuronal swelling was seen as early as 10 min post-DOM, which has been linked to non-NMDAR-mediated depolarization and release of endogenous glutamate. That DOM toxicity is dictated by iGluRs is supported by the finding that increased efficacy and potency of DOM with in vitro neuronal maturation are positively correlated with elevated protein levels of iGluR subunits, including NR1, GluR1, GluR2/3, GluR5, and GluR6/7. We determined the time course of DOM excitotoxicity. At >10 microM maximal neuronal death occurs within 2 h, while doses < or = 10 microM continue to produce death during the subsequent 22-h washout period, indicating a quicker progression of the neuronal death cascade with high DOM concentrations. Accordingly, NBQX applied 30 min post-DOM afforded better protection against low dose/prolonged duration (3 microM/24 h) than against high dose/brief duration exposure (50 microM/10 min). Interestingly, prior exposure to subthreshold DOM dose-dependently aggravated toxicity produced by a subsequent exposure to DOM. These findings provide greater insight into the complex properties underlying DOM toxicity, including the sequential involvement of multiple GluRs, greater potency with increasing neuronal maturation and protein levels of iGluRs, varying efficacy depending on dose, duration, and prior history of DOM exposure.
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Affiliation(s)
- Shenfeng Qiu
- Environmental Toxicology Graduate Program, University of California at Riverside, Riverside, California 92521, USA
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37
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Scallet AC, Schmued LC, Johannessen JN. Neurohistochemical biomarkers of the marine neurotoxicant, domoic acid. Neurotoxicol Teratol 2005; 27:745-52. [PMID: 16203121 DOI: 10.1016/j.ntt.2005.06.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2004] [Accepted: 02/01/2005] [Indexed: 11/25/2022]
Abstract
Domoic acid and its potent excitotoxic analogues glutamic acid and kainic acid, are synthesized by marine algae such as seaweed and phytoplankton. During an algal bloom, domoic acid may enter the food web through its consumption by a variety of marine organisms held in high regard as seafoods by both animals and humans. These seafoods include clams, mussels, oysters, anchovies, sardines, crabs, and scallops, among others. Animals, such as pelicans, cormorants, loons, grebes, sea otters, dolphins, and sea lions, which consume seafood contaminated with domoic acid, suffer disorientation and often death. Humans consuming contaminated seafood may suffer seizures, amnesia and also sometimes death. In addition to analytical measurement of domoic acid exposure levels in algae and/or seafood, it is useful to be able to identify the mode of toxicity through post-mortem evaluation of the intoxicated animal. In the present study, using the rat as an animal model of domoic acid intoxication, we compared histochemical staining of the limbic system and especially the hippocampus with degeneration-selective techniques (Fluoro-Jade and silver), a conventional Nissl stain for cytoplasm (Cresyl violet), a myelin-selective stain (Black-Gold), an astrocyte-specific stain (glial fibrillary acidic protein), early/immediate gene responses (c-Fos and c-Jun), as well as for heat shock protein (HSP-72) and blood-brain barrier integrity (rat IgG). The results demonstrate that the degeneration-selective stains are the biomarkers of domoic acid neurotoxicity that are the most useful and easy to discern when screening brain sections at low magnification. We also observed that an impairment of blood-brain barrier integrity within the piriform cortex accompanied the onset of domoic acid neurotoxicity.
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Affiliation(s)
- Andrew C Scallet
- Division of Neurotoxicology, National Center for Toxicological Research/FDA 3900 NCTR Drive, Jefferson, Arkansas 72079, USA.
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38
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Colman JR, Nowocin KJ, Switzer RC, Trusk TC, Ramsdell JS. Mapping and reconstruction of domoic acid-induced neurodegeneration in the mouse brain. Neurotoxicol Teratol 2005; 27:753-67. [PMID: 16109471 DOI: 10.1016/j.ntt.2005.06.009] [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] [Received: 09/20/2004] [Accepted: 02/28/2005] [Indexed: 11/16/2022]
Abstract
Domoic acid, a potent neurotoxin and glutamate analog produced by certain species of the marine diatom Pseudonitzschia, is responsible for several human and wildlife intoxication events. The toxin characteristically damages the hippocampus in exposed humans, rodents, and marine mammals. Histochemical studies have identified this, and other regions of neurodegeneration, though none have sought to map all brain regions affected by domoic acid. In this study, mice exposed (i.p.) to 4 mg/kg domoic acid for 72 h exhibited behavioral and pathological signs of neurotoxicity. Brains were fixed by intracardial perfusion and processed for histochemical analysis. Serial coronal sections (50 microm) were stained using the degeneration-sensitive cupric silver staining method of DeOlmos. Degenerated axons, terminals, and cell bodies, which stained black, were identified and the areas of degeneration were mapped onto Paxinos mouse atlas brain plates using Adobe Illustrator CS. The plates were then combined to reconstruct a 3-dimensional image of domoic acid-induced neurodegeneration using Amira 3.1 software. Affected regions included the olfactory bulb, septal area, and limbic system. These findings are consistent with behavioral and pathological studies demonstrating the effects of domoic acid on cognitive function and neurodegeneration in rodents.
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Affiliation(s)
- J R Colman
- Marine Biotoxins Program, Coastal Research Branch, Center for Coastal Environmental Health and Biomolecular Research, NOAA-National Ocean Service, 219 Fort Johnson Rd., Charleston, SC 29412, USA
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39
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Costa LG, Guizzetti M, Vitalone A. Diet-brain connections: role of neurotoxicants. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2005; 19:395-400. [PMID: 21783503 DOI: 10.1016/j.etap.2004.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In certain cases, the consumption of food or beverages can lead to intoxication and disease. Such food-induced intoxications may be due to microbial toxins, to toxic substances naturally occurring in some foods, or to contaminants or residues of various kinds. Some of these agents have neurotoxic properties and may contribute to the etiology of certain psychiatric disorders or neurodegenerative diseases. This paper reviews a selected number of dietary neurotoxicants that naturally, or as a result of human interventions, find their way into food or beverages, and have been associated with neurotoxic outcomes in humans. Chosen examples include domoic acid, a phycotoxin associated with amnesic shellfish poisoning; β-N-oxalylamine-l-alanine (l-BOAA), present in chickling peas and believed to be responsible for neurolathyrism; and two alcohols, methanol and ethanol, which can cause severe neurotoxic effects in adults and the developing fetus.
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Affiliation(s)
- L G Costa
- Department of Environmental and Occupational Health Sciences, University of Washington, 4225 Roosevelt Way NE, #100, Seattle, WA 98105-6099, USA; Department of Pharmacology and Human Physiology, University of Bari Medical School, Bari, Italy
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Chandrasekaran A, Ponnambalam G, Kaur C. Domoic acid-induced neurotoxicity in the hippocampus of adult rats. Neurotox Res 2004; 6:105-17. [PMID: 15325963 DOI: 10.1007/bf03033213] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Domoic acid (DA), an agonist of non-N-methyl-D-aspartate (non-NMDA) receptor subtype including kainate receptor, was identified as a potent neurotoxin showing involvement in neuropathological processes like neuronal degeneration and atrophy. In the past decade evidence indicating a role for excitatory amino acids in association with neurological disorders has been accumulating. Although the mechanisms underlying the neuronal damage induced by DA are not yet fully understood, many intracellular processes are thought to contribute towards DA-induced excitotoxic injury, acting in combination leading to cell death. In this review article, we report the leading hypotheses in the understanding of DA-induced neurotoxicity, which focus on the role of DA in neuropathological manifestations, the formation of the retrograde messenger molecule nitric oxide (NO) for the production of free radicals in the development of neuronal damage, the activation of glial cells (microglia and astrocytes) in response to DA-induced neuronal damage and the neuroprotective role of melatonin as a free radical scavenger or antioxidant in DA-induced neurotoxicity. The possible implications of molecular mechanism underlying the neurotoxicity in association with necrosis, apoptosis, nitric oxide synthases (nNos and iNOS) and glutamate receptors (NMDAR1 and GluR2) related genes and their expression in DA-induced neuronal damage in the hippocampus have been discussed.
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Affiliation(s)
- Ananth Chandrasekaran
- Department of Anatomy, Faculty of Medicine, National University of Singapore, MD 10, 4 Medical Drive, Singapore-117597
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41
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Erin N, Billingsley ML. Domoic acid enhances Bcl-2-calcineurin-inositol-1,4,5-trisphosphate receptor interactions and delayed neuronal death in rat brain slices. Brain Res 2004; 1014:45-52. [PMID: 15212990 DOI: 10.1016/j.brainres.2004.03.076] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/31/2004] [Indexed: 10/26/2022]
Abstract
Mechanisms of neuronal death following neuronal damage due to domoic acid are not completely defined. Bcl-2, a survival protein, protects neurons from ischemia and excitotoxin-induced damage. We previously demonstrated that Bcl-2 shuttles calcineurin to its substrates and may regulate calcium release from internal stores during neuronal ischemia. We now confirm that during excitotoxicity induced by domoic acid, calcineurin-Bcl-2 and calcineurin-1,4,5-inositol-trisphosphate receptor (IP3-R) interactions increase. Furthermore, we now show that calcineurin-IP3-R interactions are mediated by Bcl-2 in brain slices following short-term treatment with domoic acid (10 microM). Domoic acid induced late neuronal death and caspase-3-like activity in organotypic cortical and hippocampal cultures. These experiments further define the mechanisms by which neurons respond to excitotoxic insults, and suggest that interactions between calcineurin and its target proteins may influence cellular responses to injury.
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Affiliation(s)
- Nuray Erin
- Department of Pharmacology, College of Medicine, Pennsylvania State University, H078 Hospital, 500 University Drive, Hershey, PA 17033, USA
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Jeffery B, Barlow T, Moizer K, Paul S, Boyle C. Amnesic shellfish poison. Food Chem Toxicol 2004; 42:545-57. [PMID: 15019178 DOI: 10.1016/j.fct.2003.11.010] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2002] [Accepted: 11/07/2003] [Indexed: 11/22/2022]
Abstract
Amnesic shellfish poisoning (ASP) is caused by consumption of shellfish that have accumulated domoic acid, a neurotoxin produced by some strains of phytoplankton. The neurotoxic properties of domoic acid result in neuronal degeneration and necrosis in specific regions of the hippocampus. A serious outbreak of ASP occurred in Canada in 1987 and involved 150 reported cases, 19 hospitalisations and 4 deaths after consumption of contaminated mussels. Symptoms ranged from gastrointestinal disturbances, to neurotoxic effects such as hallucinations, memory loss and coma. Monitoring programmes are in place in numerous countries worldwide and closures of shellfish harvesting areas occur when domoic acid concentrations exceed regulatory limits. This paper reviews the chemistry, sources, metabolism and toxicology of domoic acid as well as human case reports of ASP and discusses a possible mechanism of toxicity.
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Affiliation(s)
- B Jeffery
- Food Standards Agency, Aviation House, 125 Kingsway, London WC2B 6NH, UK.
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Scallet AC, Kowalke PK, Rountree RL, Thorn BT, Binienda ZK. Electroencephalographic, behavioral, and c-fos responses to acute domoic acid exposure. Neurotoxicol Teratol 2004; 26:331-42. [PMID: 15019966 DOI: 10.1016/j.ntt.2003.10.004] [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] [Received: 05/13/2003] [Revised: 08/12/2003] [Accepted: 10/03/2003] [Indexed: 11/17/2022]
Abstract
Domoic acid, a potent excitotoxic analogue of glutamate and kainate, may cause seizures, amnesia, and sometimes death in humans consuming contaminated shellfish. Continuous behavioral observations and recordings of the electrocorticogram (ECoG, via bipolar, epidural electrodes) were obtained from nonanesthetized rats for 2 h after intraperitoneal injection with either saline, 2.2, or 4.4 mg/kg of domoic acid. Rats were then sacrificed for c-fos immunohistochemistry. Fast Fourier transformation (FFT) of the ECoG data to obtain the voltage as a function of frequency indicated that the lower frequency bands (theta, 4.75-6.75 Hz and delta, 1.25-4.50 Hz) were the first to respond, with a significant elevation by 30 min after the high dose of domoic acid. The lower dose of domoic acid also caused a significant elevation of ECoG voltage, but not until later in the session. Sixty minutes after dosing, the behavioral biomarkers of "ear scratching" and "rearing, praying" (RP) seizures became significantly elevated in the high-dose rats. The low-dose rats showed no significant alterations in behavior at any time during the session. In postmortem brains obtained immediately after the sessions, c-fos was activated in the anterior olfactory nucleus by both the low and high doses of domoic acid. However, only the high dose increased c-fos immunoreactivity in the hippocampus, affecting both the granule and pyramidal neurons. These data indicate that electroencephalographic and c-fos responses can be obtained at a dose of domoic acid that fails to activate the behavioral response most commonly used as a bioassay for this marine toxin: ear scratching with the ipsilateral foot.
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Affiliation(s)
- Andrew C Scallet
- Division of Neurotoxicology, National Center for Toxicological Research, USFDA, 3900 NCTR Drive, Jefferson, AR 72079, USA.
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Mayer AMS, Hall M, Fay MJ, Lamar P, Pearson C, Prozialeck WC, Lehmann VKB, Jacobson PB, Romanic AM, Uz T, Manev H. Effect of a short-term in vitro exposure to the marine toxin domoic acid on viability, tumor necrosis factor-alpha, matrix metalloproteinase-9 and superoxide anion release by rat neonatal microglia. BMC Pharmacol 2004; 1:7. [PMID: 11686853 PMCID: PMC59507 DOI: 10.1186/1471-2210-1-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2001] [Accepted: 10/02/2001] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND The excitatory amino acid domoic acid, a glutamate and kainic acid analog, is the causative agent of amnesic shellfish poisoning in humans. No studies to our knowledge have investigated the potential contribution to short-term neurotoxicity of the brain microglia, a cell type that constitutes circa 10% of the total glial population in the brain. We tested the hypothesis that a short-term in vitro exposure to domoic acid, might lead to the activation of rat neonatal microglia and the concomitant release of the putative neurotoxic mediators tumor necrosis factor-alpha (TNF-alpha), matrix metalloproteinases-2 and-9 (MMP-2 and -9) and superoxide anion (O2-). RESULTS In vitro, domoic acid [10 microM-1 mM] was significantly neurotoxic to primary cerebellar granule neurons. Although neonatal rat microglia expressed ionotropic glutamate GluR4 receptors, exposure during 6 hours to domoic acid [10 microM-1 mM] had no significant effect on viability. By four hours, LPS (10 ng/mL) stimulated an increase in TNF-alpha mRNA and a 2,233 % increase in TNF-alpha protein In contrast, domoic acid (1 mM) induced a slight rise in TNF-alpha expression and a 53 % increase (p < 0.01) of immunoreactive TNF-alpha protein. Furthermore, though less potent than LPS, a 4-hour treatment with domoic acid (1 mM) yielded a 757% (p < 0.01) increase in MMP-9 release, but had no effect on MMP-2. Finally, while PMA (phorbol 12-myristate 13-acetate) stimulated O2- generation was elevated in 6 hour LPS-primed microglia, a similar pretreatment with domoic acid (1 mM) did not prime O2- release. CONCLUSIONS To our knowledge this is the first experimental evidence that domoic acid, at in vitro concentrations that are toxic to neuronal cells, can trigger a release of statistically significant amounts of TNF-alpha and MMP-9 by brain microglia. These observations are of considerable pathophysiological significance because domoic acid activates rat microglia several days after in vivo administration.
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Affiliation(s)
- Alejandro MS Mayer
- Department of Pharmacology, Chicago College of Osteopathic Medicine, Midwestern University, 555 31st Street, Downers Grove, Illinois 60515, USA
| | - Mary Hall
- Department of Pharmacology, Chicago College of Osteopathic Medicine, Midwestern University, 555 31st Street, Downers Grove, Illinois 60515, USA
| | - Michael J Fay
- Department of Pharmacology, Chicago College of Osteopathic Medicine, Midwestern University, 555 31st Street, Downers Grove, Illinois 60515, USA
| | - Peter Lamar
- Department of Pharmacology, Chicago College of Osteopathic Medicine, Midwestern University, 555 31st Street, Downers Grove, Illinois 60515, USA
| | - Celeste Pearson
- Department of Pharmacology, Chicago College of Osteopathic Medicine, Midwestern University, 555 31st Street, Downers Grove, Illinois 60515, USA
| | - Walter C Prozialeck
- Department of Pharmacology, Chicago College of Osteopathic Medicine, Midwestern University, 555 31st Street, Downers Grove, Illinois 60515, USA
| | - Virginia KB Lehmann
- School of Chemical Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | | | - Anne M Romanic
- GlaxoSmithKline Pharmaceuticals, Department of Cardiovascular Pharmacology, King of Prussia, Pennsylvania 19406, USA
| | - Tolga Uz
- The Psychiatric Institute, University of Illinois at Chicago, Chicago, Illinois 60612, USA
| | - Hari Manev
- The Psychiatric Institute, University of Illinois at Chicago, Chicago, Illinois 60612, USA
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45
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Ananth C, Gopalakrishnakone P, Kaur C. Protective role of melatonin in domoic acid-induced neuronal damage in the hippocampus of adult rats. Hippocampus 2003; 13:375-87. [PMID: 12722978 DOI: 10.1002/hipo.10090] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Domoic acid (DA), a kainite-receptor agonist and potent inducer of neurotoxicity, has been administered intravenously in adult rats in the present study (0.75 mg/kg body weight) to demonstrate neuronal degeneration followed by glial activation and their involvement with inducible nitric oxide synthase (iNOS) in the hippocampus. An equal volume of normal saline was administered in control rats. The pineal hormone melatonin, which protects the neurons efficiently against excitotoxicity mediated by sensitive glutamate receptor, was administered intraperitoneally (10 mg/kg body weight), 20 min before, immediately after, and 1 h and 2 h after the DA administration, to demonstrate its role in therapeutic strategy. Histopathological analysis (Nissl staining) demonstrated extensive neuronal damage in the pyramidal neurons of CA1, CA3 subfields and hilus of the dentate gyrus (DG) in the hippocampus at 5 days after DA administration. Sparsely distributed glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes were observed in the hippocampus at 4-24 h after DA administration and in the control rats. Astrogliosis was evidenced by increased GFAP immunoreactivity in the areas of severe neuronal degeneration at 5 days after DA administration. Along with this, microglial cells exhibited an intense immunoreaction with OX-42, indicating upregulation of complement type 3 receptors (CR3). Ultrastructural study revealed swollen or shrunken degenerating neurons in the CA1, CA3 subfields and hilus of the DG and hypertrophied astrocytes showing accumulation of intermediate filament bundles in the cytoplasm were observed after administration of DA. Although no significant change could be observed in the mRNA level of iNOS expression between the DA-treated rats and controls at 4-24 h and at 5-day time intervals, double immunofluorescense revealed co-expression of induced iNOS with GFAP immunoreactive astrocytes, but not in the microglial cells, and iNOS expression in the neurons of the hippocampal subfields at 5 days after DA administration. Expression of iNOS was not observed in the hippocampus of control rats. DA-induced neuronal death, glial activation, and iNOS protein expression were attenuated significantly by melatonin treatment and were comparable to the control groups. The results of the present study suggest that melatonin holds potential for the treatment of pathologies associated with DA-induced brain damage. It is speculated that astrogliosis and induction of iNOS protein expression in the neurons and astrocytes of the hippocampus may be in response to DA-induced neuronal degeneration.
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Affiliation(s)
- C Ananth
- Department of Anatomy, Faculty of Medicine, National University of Singapore, Singapore
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46
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Ananth C, Dheen ST, Gopalakrishnakone P, Kaur C. Distribution of NADPH-diaphorase and expression of nNOS, N-methyl-D-aspartate receptor (NMDAR1) and non-NMDA glutamate receptor (GlutR2) genes in the neurons of the hippocampus after domoic acid-induced lesions in adult rats. Hippocampus 2003; 13:260-72. [PMID: 12699333 DOI: 10.1002/hipo.10060] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Neuronal degeneration followed by detection of nitric oxide (NO)-producing neurons of the hippocampus was investigated at 4 h, 16 h, 24 h, 2 days, 5 days, and 14 days after administration of domoic acid (DA), in the present study. Histopathological analysis (Nissl staining) displayed dark-stained degenerating neurons in the hippocampus at 24 h to 14 days after DA administration, with degeneration most severe at 5-14 days. NADPH-d-positive neurons were observed in different subfields of the hippocampus in control rats and DA treated rats at 4-24 h. Complete loss of NADPH-d-positive neurons in the CA1 and CA3 subfields and also in the hilus of dentate gyrus (DG) was observed at 5 days and 14 days after the administration of DA. In contrast, at 4-24 h, neuronal nitric oxide synthase (nNOS)-immunoreactive cells were absent from the hippocampal subfields in control and DA-treated animals but were observed at 5 days and 14 days after DA administration. N-methyl-D-aspartate receptor (NMDAR1) immunoreactivity was increased in the hippocampal neurons at 5 days after DA administration and double immunofluorescence demonstrated its coexpression with induced nNOS expression. No significant change could be observed in the immunoreactivity of non-NMDA receptor (GlutR2) as compared with the controls, while occasional immunoreactive neurons were colocalized with induced nNOS expression. Reverse transcription-polymerase chain reaction analysis showed the upregulated expression of nNOS and downregulated expression of NMDAR1 at 5 days after the administration of DA. Although nNOS mRNA expression was rapidly induced at 5 days after DA administration, in situ hybridization analysis revealed complete loss of nNOS mRNA expression in the region of neuronal degeneration in the hippocampus at 24 h and 5 days after DA administration. The present study has shown that NADPH-d and nNOS express differentially in the neurons of the hippocampus in DA-induced neurotoxicity. It is speculated that induction of nNOS and glutamate receptor genes in the neurons of the hippocampus in response to DA-induced neurotoxicity could have contributed to the neuronal degeneration.
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Affiliation(s)
- C Ananth
- Department of Anatomy, Faculty of Medicine, National University of Singapore, Singapore
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47
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Ananth C, Gopalakrishnakone P, Kaur C. Induction of inducible nitric oxide synthase expression in activated microglia following domoic acid (DA)-induced neurotoxicity in the rat hippocampus. Neurosci Lett 2003; 338:49-52. [PMID: 12565138 DOI: 10.1016/s0304-3940(02)01351-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Neuronal degeneration followed by glial activation (microglia and astrocytes) and nitric oxide synthase (NOS) expression in the hippocampus was investigated at 3 months after domoic acid (DA) administration and compared with DA treated rats at 5 days time interval which was reported earlier. Massive degeneration with complete absence of neurons in the hippocampal CA1 and CA3 regions and hypertrophied microglial cells showing intense immunoreaction with the antibody OX-42 was observed at 3 months after DA administration. Sparsely distributed OX-42 positive microglial cells were observed in the hippocampus of control rats at 3 months after saline treatment No apparent changes could be observed in the immunoreactivity of GFAP at 3 months after saline and DA administration. Neuronal nitric oxide synthase immunoreactive neurons were completely absent in the hippocampus at 3 months after DA administration. In contrast, nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) histochemical analysis revealed absence of NADPH-d reactivity in the neurons, but positive reactivity in the microglial cells of CA1-CA3 regions in the hippocampus after DA treatment. Double immunofluorescense revealed co-expression of inducible nitric oxide synthase with immunoreactive OX-42 positive microglial cells in the hippocampal subfields at 3 months after DA administration. The microglia-produced NO appears to be a secondary phenomenon in the prolonged inflammatory process following DA-induced neuronal degeneration.
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Affiliation(s)
- C Ananth
- Department of Anatomy, Faculty of Medicine, National University of Singapore, MD 10, 4 Medical Drive, Singapore 117597, Singapore
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48
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Abstract
We have modified the cell-based directed cytotoxicity assay for sodium channel and calcium channel active phycotoxins using a c-fos-luciferase reporter gene construct. In this report we describe the conceptual basis to the development of reporter gene assays for algal-derived toxins and summarize both published and unpublished data using this method. N2A mouse neuroblastoma cells, which express voltage-dependent sodium channels, were stably transfected with the reporter gene c-fos-luc, which contains the firefly luciferase gene under the transcriptional regulation of the human c-fos response element. The characteristics of the N2A reporter gene assay were determined by dose response with brevetoxin and ciguatoxin. Brevetoxin-1 and ciguatoxin-1 induced c-fos-luc with an EC50 of 4.6 and 3.0 ng ml(-1), respectively. Saxitoxin caused a concentration-dependent inhibition of brevetoxin-1 induction of c-fos-luc with an EC50 of 3.5 ng ml(-1). GH4C1 rat pituitary cells, which lack voltage-dependent sodium channels but express voltage-dependent calcium channels, were also stably transfected with the c-fos-luc. GH4C1 cells expressing c-fos-luciferase were responsive to maitotoxin (1 ng ml(-1)) and a putative toxin produced by Pfiesteria piscicida. Although reporter gene assays are not designed to replace existing detection methods used to measure toxin activity in seafood, they do provide a valuable means to screen algal cultures for toxin activity, to conduct assay-guided fractionation and to characterize pharmacologic properties of algal toxins.
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Affiliation(s)
- E R Fairey
- Marine Biotoxins Program, NOAA-National Ocean Service, Center for Coastal Environmental Health and Biomolecular Research, Charleston, SC 29412, USA
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49
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Zhu X, Jin S, Ng YK, Lee WL, Wong PT. Positive and negative modulation by AMPA- and kainate-receptors of striatal kainate injection-induced neuronal loss in rat forebrain. Brain Res 2001; 922:293-8. [PMID: 11743962 DOI: 10.1016/s0006-8993(01)03159-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We investigated the roles of ionotropic glutamate receptor subtypes in mediating striatal kainate injection-induced neuronal loss in rat forebrain, using subtype-specific antagonists and histochemical staining. Our study demonstrates that kainate injected unilaterally into the striatum induces a massive neuronal loss in the rat ipsilateral forebrain through activation of kainate receptors and, to a limited extent, a consequent involvement of M-methyl-D-aspartate (NMDA) receptors, whereas activation of alpha-amino-3-hydroxy-5-methylisoxazol-4-propionate (AMPA) receptors shows a neuroprotective effect. These and previous results suggest that three subtypes of ionotropic glutamate receptors play differential roles in mediating excitatory amino acid (EAA)-induced neurodegeneration.
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Affiliation(s)
- X Zhu
- Department of Pharmacology, Faculty of Medicine, The National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260
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50
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Sari P, Kerr DS. Domoic acid-induced hippocampal CA1 hyperexcitability independent of region CA3 activity. Epilepsy Res 2001; 47:65-76. [PMID: 11673022 DOI: 10.1016/s0920-1211(01)00295-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Domoic acid (DOM) is a potent agonist of AMPA and kainic acid (KA) receptors in the CNS and is known to produce seizures acutely, and lasting excitotoxic damage in several brain regions. While the excitotoxic effects of DOM are well documented, its seizurogenic properties are less clear. In this study, we assessed the acute effects of DOM and KA in region CA1 of intact rat hippocampal slices (CA3-on) and in slices lacking region CA3 (CA3-off). Orthodromic Schaffer collateral-evoked CA1 field potentials (population spikes and somal EPSP's) were monitored during DOM and KA (10-500 nM) administration. In CA3-off slices both KA and DOM produced immediate increases in CA1 population spike amplitude. With prolonged exposure, lasting dose-dependent reductions in spike amplitude and EPSP slope were observed, possibly due to depolarising conduction block following excessive AMPA/KA receptor activation; DOM was several-fold more potent than KA in this regard. Population spike threshold did not vary with DOM, but in CA3-on slices a dose-dependent steepening of the I/O curve and increase in maximum spike amplitude was seen. CA1 hyperexcitability, as evidenced by the appearance of prominent second and third population spikes, was equivalently increased across a range of DOM concentrations in both CA3-on and CA3-off slices and, in general, DOM-induced CA1 hyperexcitability was not enhanced by the presence of CA3 for any of the other variables assessed in this study. These findings show that DOM directly promotes neuronal hyperactivity in region CA1, presumably due to tonic AMPA and/or KA-receptor mediated depolarization, and further suggests that DOM-induced hyperactivity in the recurrently networked, AMPA/KA-receptor rich region CA3 does not contribute to the onset and spread of limbic seizures during relatively mild DOM intoxication.
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Affiliation(s)
- P Sari
- Department of Pharmacology, University of Otago School of Medical Sciences, PO Box 913, Dunedin, New Zealand
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