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Hendrix AM, Lefebvre KA, Bowers EK, Stuppard R, Burbacher T, Marcinek DJ. Age and Sex as Determinants of Acute Domoic Acid Toxicity in a Mouse Model. Toxins (Basel) 2023; 15:259. [PMID: 37104198 PMCID: PMC10143184 DOI: 10.3390/toxins15040259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/15/2023] [Accepted: 03/21/2023] [Indexed: 04/05/2023] Open
Abstract
The excitatory neurotoxin domoic acid (DA) consistently contaminates food webs in coastal regions around the world. Acute exposure to the toxin causes Amnesic Shellfish Poisoning, a potentially lethal syndrome of gastrointestinal- and seizure-related outcomes. Both advanced age and male sex have been suggested to contribute to interindividual DA susceptibility. To test this, we administered DA doses between 0.5 and 2.5 mg/kg body weight to female and male C57Bl/6 mice at adult (7-9-month-old) and aged (25-28-month-old) life stages and observed seizure-related activity for 90 min, at which point we euthanized the mice and collected serum, cortical, and kidney samples. We observed severe clonic-tonic convulsions in some aged individuals, but not in younger adults. We also saw an association between advanced age and the incidence of a moderately severe seizure-related outcome, hindlimb tremors, and between advanced age and overall symptom severity and persistence. Surprisingly, we additionally report that female mice, particularly aged female mice, demonstrated more severe neurotoxic symptoms following acute exposure to DA than males. Both age and sex patterns were reflected in tissue DA concentrations as well: aged mice and females had generally higher concentrations of DA in their tissues at 90 min post-exposure. This study contributes to the body of work that can inform intelligent, evidence-based public health protections for communities threatened by more frequent and extensive DA-producing algal blooms.
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Affiliation(s)
- Alicia M. Hendrix
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98195, USA
| | - Kathi A. Lefebvre
- Environmental Fisheries Science Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA 98112, USA
| | - Emily K. Bowers
- Environmental Fisheries Science Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA 98112, USA
| | - Rudolph Stuppard
- Department of Radiology, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Thomas Burbacher
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98195, USA
| | - David J. Marcinek
- Department of Radiology, University of Washington School of Medicine, Seattle, WA 98195, USA
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Ferriss BE, Marcinek DJ, Ayres D, Borchert J, Lefebvre KA. Acute and chronic dietary exposure to domoic acid in recreational harvesters: A survey of shellfish consumption behavior. ENVIRONMENT INTERNATIONAL 2017; 101:70-79. [PMID: 28109640 PMCID: PMC5348270 DOI: 10.1016/j.envint.2017.01.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 01/05/2017] [Accepted: 01/06/2017] [Indexed: 05/25/2023]
Abstract
Domoic acid (DA) is a neurotoxin that is naturally produced by phytoplankton and accumulates in seafood during harmful algal blooms. As the prevalence of DA increases in the marine environment, there is a critical need to identify seafood consumers at risk of DA poisoning. DA exposure was estimated in recreational razor clam (Siliqua patula) harvesters to determine if exposures above current regulatory guidelines occur and/or if harvesters are chronically exposed to low levels of DA. Human consumption rates of razor clams were determined by distributing 1523 surveys to recreational razor clam harvesters in spring 2015 and winter 2016, in Washington, USA. These consumption rate data were combined with DA measurements in razor clams, collected by a state monitoring program, to estimate human DA exposure. Approximately 7% of total acute exposures calculated (including the same individuals at different times) exceeded the current regulatory reference dose (0.075mgDA·kgbodyweight-1·d-1) due to higher than previously reported consumption rates, lower bodyweights, and/or by consumption of clams at the upper range of legal DA levels (maximum 20mg·kg-1 wet weight for whole tissue). Three percent of survey respondents were potentially at risk of chronic DA exposure by consuming a minimum of 15 clams per month for at 12 consecutive months. These insights into DA consumption will provide an additional tool for razor clam fishery management.
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Affiliation(s)
- Bridget E Ferriss
- Department of Radiology, University of Washington, Seattle, WA 98195, USA.
| | - David J Marcinek
- Department of Radiology, Pathology, and Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Daniel Ayres
- WA State Department of Fish and Wildlife, 48 Devonshire Road, Montesano, WA 98563, USA
| | - Jerry Borchert
- WA State Department of Health, 243 Israel Road SE, Tumwater, WA 98501, USA
| | - Kathi A Lefebvre
- Environmental and Fisheries Science Division, Northwest Fisheries Science Center, National Marine Fisheries Service, NOAA, 2725 Montlake Blvd. East, Seattle, WA 98112, USA
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Woodward NC, Pakbin P, Saffari A, Shirmohammadi F, Haghani A, Sioutas C, Cacciottolo M, Morgan TE, Finch CE. Traffic-related air pollution impact on mouse brain accelerates myelin and neuritic aging changes with specificity for CA1 neurons. Neurobiol Aging 2017; 53:48-58. [PMID: 28212893 PMCID: PMC5388507 DOI: 10.1016/j.neurobiolaging.2017.01.007] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 11/16/2016] [Accepted: 01/05/2017] [Indexed: 12/28/2022]
Abstract
Traffic-related air pollution (TRAP) is associated with lower cognition and reduced white matter volume in older adults, specifically for particulate matter <2.5-μm diameter (PM2.5). Rodents exposed to TRAP have shown microglial activation and neuronal atrophy. We further investigated age differences of TRAP exposure, with focus on hippocampus for neuritic atrophy, white matter degeneration, and microglial activation. Young- and middle-aged mice (3 and 18 months female C57BL/6J) were exposed to nanoscale-PM (nPM, <0.2 μm diameter). Young mice showed selective changes in the hippocampal CA1 region, with neurite atrophy (-25%), decreased MBP (-50%), and increased Iba1 (+50%), with dentate gyrus relatively unaffected. Exposure to nPM of young mice decreased GluA1 protein (-40%) and increased TNFa mRNA (10×). Older controls had age changes approximating nPM effects on young, with no response to nPM, suggesting an age-ceiling effect. The CA1 selective vulnerability in young mice parallels CA1 vulnerability in Alzheimer's disease. We propose that TRAP-associated human cognitive and white matter changes involve hippocampal responses to nPM that begin at younger ages.
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Affiliation(s)
- Nicholas C Woodward
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, USA
| | - Payam Pakbin
- Department of Civil and Environmental Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA
| | - Arian Saffari
- Department of Civil and Environmental Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA
| | - Farimah Shirmohammadi
- Department of Civil and Environmental Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA
| | - Amin Haghani
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, USA
| | - Constantinos Sioutas
- Department of Civil and Environmental Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA
| | - Mafalda Cacciottolo
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, USA
| | - Todd E Morgan
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, USA
| | - Caleb E Finch
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, USA; Department of Molecular and Computational Biology, Dornsife College, University of Southern California, Los Angeles, CA, USA.
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Giordano G, Kavanagh TJ, Faustman EM, White CC, Costa LG. Low-level domoic acid protects mouse cerebellar granule neurons from acute neurotoxicity: role of glutathione. Toxicol Sci 2013; 132:399-408. [PMID: 23315585 PMCID: PMC3693515 DOI: 10.1093/toxsci/kft002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Accepted: 12/28/2012] [Indexed: 11/14/2022] Open
Abstract
Domoic acid (DomA) is a potent marine neurotoxin. By activating α-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid/kainate receptors, DomA induces oxidative stress-mediated apoptotic cell death in neurons. The effect of prolonged (10 days) exposure to a low, nontoxic concentration (5nM) of DomA on acute (intermediate concentration) neurotoxicity of this toxin was investigated in cerebellar granule neurons (CGNs) from wild-type mice and mice lacking the glutamate cysteine ligase (GCL) modifier subunit (Gclm (/)). CGNs from Gclm (/) mice have very low glutathione (GSH) levels and are very sensitive to DomA toxicity. In CGNs from wild-type mice, prolonged exposure to 5nM DomA did not cause any overt toxicity but reduced oxidative stress-mediated apoptotic cell death induced by exposure to an intermediate concentration (100nM for 24h) of DomA. This protection was not observed in CGNs from Gclm (/) mice. Prolonged DomA exposure increased GSH levels in CGNs of wild-type but not Gclm (/) mice. Levels of GCLC (the catalytic subunit of GCL) protein and mRNA were increased in CGNs of both mouse strains, whereas levels of GCLM protein and mRNA, activity of GCL, and levels of GCL holoenzyme were only increased in CGNs of wild-type mice. Chronic DomA exposure also protected wild-type CGNs from acute toxicity of other oxidants. The results indicate that CGNs from Gclm (/) mice, which are already more sensitive to DomA toxicity, are unable to upregulate their GSH levels. As Gclm (/) mice may represent a model for a common human polymorphism in GCLM, such individuals may be at particular risk for DomA-induced neurotoxicity.
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Affiliation(s)
- Gennaro Giordano
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington 98105, USA.
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Head BP, Peart JN, Panneerselvam M, Yokoyama T, Pearn ML, Niesman IR, Bonds JA, Schilling JM, Miyanohara A, Headrick J, Ali SS, Roth DM, Patel PM, Patel HH. Loss of caveolin-1 accelerates neurodegeneration and aging. PLoS One 2010; 5:e15697. [PMID: 21203469 PMCID: PMC3009734 DOI: 10.1371/journal.pone.0015697] [Citation(s) in RCA: 131] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Accepted: 11/29/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The aged brain exhibits a loss in gray matter and a decrease in spines and synaptic densities that may represent a sequela for neurodegenerative diseases such as Alzheimer's. Membrane/lipid rafts (MLR), discrete regions of the plasmalemma enriched in cholesterol, glycosphingolipids, and sphingomyelin, are essential for the development and stabilization of synapses. Caveolin-1 (Cav-1), a cholesterol binding protein organizes synaptic signaling components within MLR. It is unknown whether loss of synapses is dependent on an age-related loss of Cav-1 expression and whether this has implications for neurodegenerative diseases such as Alzheimer's disease. METHODOLOGY/PRINCIPAL FINDINGS We analyzed brains from young (Yg, 3-6 months), middle age (Md, 12 months), aged (Ag, >18 months), and young Cav-1 KO mice and show that localization of PSD-95, NR2A, NR2B, TrkBR, AMPAR, and Cav-1 to MLR is decreased in aged hippocampi. Young Cav-1 KO mice showed signs of premature neuronal aging and degeneration. Hippocampi synaptosomes from Cav-1 KO mice showed reduced PSD-95, NR2A, NR2B, and Cav-1, an inability to be protected against cerebral ischemia-reperfusion injury compared to young WT mice, increased Aβ, P-Tau, and astrogliosis, decreased cerebrovascular volume compared to young WT mice. As with aged hippocampi, Cav-1 KO brains showed significantly reduced synapses. Neuron-targeted re-expression of Cav-1 in Cav-1 KO neurons in vitro decreased Aβ expression. CONCLUSIONS Therefore, Cav-1 represents a novel control point for healthy neuronal aging and loss of Cav-1 represents a non-mutational model for Alzheimer's disease.
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Affiliation(s)
- Brian P. Head
- Department of Anesthesiology, University of California San Diego, La Jolla, California, United States of America
- VA San Diego Healthcare System, San Diego, California, United States of America
| | - Jason N. Peart
- Heart Foundation Research Centre, Griffith University, Gold Coast, Queensland, Australia
| | - Mathivadhani Panneerselvam
- Department of Anesthesiology, University of California San Diego, La Jolla, California, United States of America
| | - Takaakira Yokoyama
- Department of Anesthesiology, University of California San Diego, La Jolla, California, United States of America
| | - Matthew L. Pearn
- Department of Anesthesiology, University of California San Diego, La Jolla, California, United States of America
| | - Ingrid R. Niesman
- Department of Anesthesiology, University of California San Diego, La Jolla, California, United States of America
| | - Jacqueline A. Bonds
- Department of Anesthesiology, University of California San Diego, La Jolla, California, United States of America
| | - Jan M. Schilling
- Department of Anesthesiology, University of California San Diego, La Jolla, California, United States of America
- VA San Diego Healthcare System, San Diego, California, United States of America
| | - Atsushi Miyanohara
- Gene Therapy Program, University of California San Diego, La Jolla, California, United States of America
| | - John Headrick
- Heart Foundation Research Centre, Griffith University, Gold Coast, Queensland, Australia
| | - Sameh S. Ali
- Department of Medicine, University of California, La Jolla, California, United States of America
| | - David M. Roth
- Department of Anesthesiology, University of California San Diego, La Jolla, California, United States of America
- VA San Diego Healthcare System, San Diego, California, United States of America
| | - Piyush M. Patel
- Department of Anesthesiology, University of California San Diego, La Jolla, California, United States of America
- VA San Diego Healthcare System, San Diego, California, United States of America
| | - Hemal H. Patel
- Department of Anesthesiology, University of California San Diego, La Jolla, California, United States of America
- VA San Diego Healthcare System, San Diego, California, United States of America
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Sawant PM, Mountfort DO, Kerr DS. Spectral analysis of electrocorticographic activity during pharmacological preconditioning and seizure induction by intrahippocampal domoic acid. Hippocampus 2010; 20:994-1002. [PMID: 19714566 DOI: 10.1002/hipo.20698] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Previously we have shown that low-dose domoic acid (DA) preconditioning produces tolerance to the behavioral effects of high-dose DA. In this study, we used electrocorticography (ECoG) to monitor subtle CNS changes during and after preconditioning. Young adult male Sprague-Dawley rats were implanted with a left cortical electrode, and acute recordings were obtained during preconditioning by contralateral intrahippocampal administration of either low-dose DA (15 pmoles) or saline, followed by a high-dose DA (100 pmoles) challenge. ECoG data were analyzed by fast Fourier transformation to obtain the percentage of baseline power spectral density (PSD) for delta to gamma frequencies (range: 1.25-100 Hz). Consistent with previous results, behavioral analysis confirmed that low-dose DA preconditioning 60 min before a high-dose DA challenge produced significant reductions in cumulative seizure scores and high level seizure behaviors. ECoG analysis revealed significant reductions in power spectral density across all frequency bands, and high-frequency/high-amplitude spiking in DA preconditioned animals, relative to saline controls. Significant correlations between seizure scores and ECoG power confirmed that behavioral analysis is a reliable marker for seizure analysis. The reduction of power in delta to gamma frequency bands in contralateral cortex does not allow a clear distinction between seizure initiation and seizure propagation, but does provide objective confirmation that pharmacological preconditioning by DA reduces network seizure activity.
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Affiliation(s)
- P M Sawant
- Department of Pharmacology and Toxicology, University of Otago School of Medical Sciences, Dunedin, New Zealand
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Sawant PM, Tyndall JDA, Holland PT, Peake BM, Mountfort DO, Kerr DS. In vivo seizure induction and affinity studies of domoic acid and isodomoic acids-D, -E and -F. Neuropharmacology 2010; 59:129-38. [PMID: 20416329 DOI: 10.1016/j.neuropharm.2010.03.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 03/15/2010] [Accepted: 03/31/2010] [Indexed: 11/20/2022]
Abstract
Domoic acid and its isomers are produced via algal blooms and are found in high concentrations in shellfish. Here, we assessed the acute seizurogenic potencies of isomers-D, -E and -F and their binding affinities at heterogeneous populations of KA receptors from rat cerebrum. In addition, binding affinities of all six isomers (Iso-A through -F) were assessed at AMPA receptors. Radioligand displacement studies indicated that the seizurogenic potency of Iso-F (E-configuration) closely correlates with its affinities at both KA and AMPA receptors, whereas isomers-D (Z) and -E (E), which exhibit distinctly lower seizurogenic potencies, are quite weak displacers. Previously observed functional potencies for isomers-A, -B and -C (Sawant et al., 2008) correlated with AMPA receptor affinities observed here. Taken together, these findings call into question previous structure-activity rules. Significantly, in our hands, Iso-D was ten-fold less potent than Iso-F. To further explain observed links between structural conformation and functional potency, molecular modeling was employed. Modeling results closely matched the rank order of potency and binding data observed. We further assessed the efficacy of isomers-D, -E and -F as pharmacological preconditioning agents. Acute preconditioning with low-dose Iso-D, -E or -F, before high-dose DA failed to impart behavioural tolerance. This study has shed new light on structural conformations affecting non-NMDA ionotropic glutamate receptor binding and functional potency, and provides a foundation for future work in areas of AMPA and KA receptor modeling.
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Affiliation(s)
- P M Sawant
- Department of Pharmacology and Toxicology, University of Otago School of Medical Sciences, Dunedin, New Zealand.
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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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Goulton CS, Patten AR, Kerr JR, Kerr DS. Pharmacological Preconditioning with GYKI 52466: A Prophylactic Approach to Neuroprotection. Front Neurosci 2010; 4. [PMID: 20953290 PMCID: PMC2955399 DOI: 10.3389/fnins.2010.00054] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Accepted: 07/02/2010] [Indexed: 11/13/2022] Open
Abstract
Some toxins and drugs can trigger lasting neuroprotective mechanisms that enable neurons to resist a subsequent severe insult. This “pharmacological preconditioning” has far-reaching implications for conditions in which blood flow to the brain is interrupted. We have previously shown that in vitro preconditioning with the AMPA receptor antagonist GYKI 52466 induces tolerance to kainic acid (KA) toxicity in hippocampus. This effect persists well after washout of the drug and may be mediated via inverse agonism of G-protein coupled receptors (GPCRs). Given the amplifying nature of metabotropic modulation, we hypothesized that GYKI 52466 may be effective in reducing seizure severity at doses well below those normally associated with adverse side effects. Here we report that pharmacological preconditioning with low-dose GYKI imparts a significant protection against KA-induced seizures in vivo. GYKI (3 mg/kg, s.c.), 90–180 min prior to high-dose KA, markedly reduced seizure scores, virtually abolished all level 3 and level 4 seizures, and completely suppressed KA-induced hippocampal c-FOS expression. In addition, preconditioned animals exhibited significant reductions in high frequency/high amplitude spiking and ECoG power in the delta, theta, alpha, and beta bands during KA. Adverse behaviors often associated with higher doses of GYKI were not evident during preconditioning. The fact that GYKI is effective at doses well-below, and at pre-administration intervals well-beyond previous studies, suggests that a classical blockade of ionotropic AMPA receptors does not underlie anticonvulsant effects. Low-dose GYKI preconditioning may represent a novel, prophylactic strategy for neuroprotection in a field almost completely devoid of effective pharmaceuticals.
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Affiliation(s)
- Chelsea S Goulton
- Department of Pharmacology and Toxicology, School of Medical Sciences, University of Otago Dunedin, New Zealand
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Lefebvre KA, Robertson A. Domoic acid and human exposure risks: A review. Toxicon 2010; 56:218-30. [DOI: 10.1016/j.toxicon.2009.05.034] [Citation(s) in RCA: 147] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2008] [Revised: 05/06/2009] [Accepted: 05/13/2009] [Indexed: 01/20/2023]
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Qiu S, Jebelli AK, Ashe JH, Currás-Collazo MC. Domoic acid induces a long-lasting enhancement of CA1 field responses and impairs tetanus-induced long-term potentiation in rat hippocampal slices. Toxicol Sci 2009; 111:140-50. [PMID: 19564213 DOI: 10.1093/toxsci/kfp141] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Domoic acid (DOM) is known to cause hippocampal neuronal damage and produces amnesic effects. We examined synaptic plasticity changes induced by DOM exposure in rat hippocampal CA1 region. Brief bath application of DOM to hippocampal slices produces a chemical form of long-term potentiation (LTP) of CA1 field synaptic potentials. The potentiation cannot be blocked by NMDA receptor antagonist MK-801 but can be blocked by the calcium-calmodulin-dependent protein kinase II (CaMKII) inhibitor KN-62 or cAMP-dependent protein kinase (PKA) inhibitor H-89. DOM-potentiated slices show decreased autophosphorylated CaMKII (p-Thr286), an effect that is also dependent on the activity of CaMKII and PKA. Increased phosphorylation of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor subunit GluR1 (p-Ser831) was seen in DOM-potentiated slices. Therefore, aberrant regulation of CaMKII and GluR1 phosphorylation occurs after DOM application. In addition, tetanus-induced LTP as well as the increase of phosphorylation of CaMKII (p-Thr286) were reduced in DOM-potentiated slices. Compared with brief exposure, slices recovering from prolonged exposure did not show potentiation or altered levels of CaMKII (p-Thr286) or GluR (p-Ser831). However, decreased phosphorylation of GluR1 at Ser845 was seen. These results describe a new chemical form of LTP and uncover novel molecular changes induced by DOM. The observed impairment of tetanus LTP and misregulation of CaMKII and GluR1 phosphorylation may partially account for DOM neurotoxicity and underlie the molecular basis for DOM-induced memory deficit.
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Affiliation(s)
- Shenfeng Qiu
- Department of Cell Biology & Neuroscience, University of California, Riverside, California 92521, USA.
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Sawant P, Holland P, Mountfort D, Kerr D. In vivo seizure induction and pharmacological preconditioning by domoic acid and isodomoic acids A, B and C. Neuropharmacology 2008; 55:1412-8. [DOI: 10.1016/j.neuropharm.2008.09.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 07/30/2008] [Accepted: 09/01/2008] [Indexed: 10/21/2022]
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Mattson MP. Hormesis and disease resistance: activation of cellular stress response pathways. Hum Exp Toxicol 2008; 27:155-62. [PMID: 18480142 DOI: 10.1177/0960327107083417] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The survival of all organisms depends upon their ability to overcome stressful conditions, an ability that involves adaptive changes in cells and molecules. Findings from studies of animal models and human populations suggest that hormesis (beneficial effects of low levels of stress) is an effective means of protecting against many different diseases including diabetes, cardiovascular disease, cancers and neurodegenerative disorders. Such stress resistance mechanisms can be bolstered by diverse environmental factors including exercise, dietary restriction, cognitive stimulation and exposure to low levels of toxins. Some commonly used vitamins and dietary supplements may also induce beneficial stress responses. Several interrelated cellular signaling molecules are involved in the process of hormesis. Examples include the gases oxygen, carbon monoxide and nitric oxide, the neurotransmitter glutamate, the calcium ion and tumor necrosis factor. In each case low levels of these signaling molecules are beneficial and protect against disease, whereas high levels can cause the dysfunction and/or death of cells. The cellular and molecular mechanisms of hormesis are being revealed and include activation of growth factor signaling pathways, protein chaperones, cell survival genes and enzymes called sirtuins. Knowledge of hormesis mechanisms is leading to novel approaches for preventing and treating a range of human diseases.
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Affiliation(s)
- Mark P Mattson
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224, USA.
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Vranyac-Tramoundanas A, Harrison JC, Clarkson AN, Kapoor M, Winburn IC, Kerr DS, Sammut IA. Domoic Acid Impairment of Cardiac Energetics. Toxicol Sci 2008; 105:395-407. [DOI: 10.1093/toxsci/kfn132] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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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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McCord MC, Lorenzana A, Bloom CS, Chancer ZO, Schauwecker PE. Effect of age on kainate-induced seizure severity and cell death. Neuroscience 2008; 154:1143-53. [PMID: 18479826 DOI: 10.1016/j.neuroscience.2008.03.082] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2008] [Revised: 03/26/2008] [Accepted: 03/31/2008] [Indexed: 10/22/2022]
Abstract
While the onset and extent of epilepsy increases in the aged population, the reasons for this increased incidence remain unexplored. The present study used two inbred strains of mice (C57BL/6J and FVB/NJ) to address the genetic control of age-dependent neurodegeneration by building upon previous experiments that have identified phenotypic differences in susceptibility to hippocampal seizure-induced cell death. We determined if seizure induction and seizure-induced cell death are affected differentially in young adult, mature, and aged male C57BL/6J and FVB/NJ mice administered the excitotoxin, kainic acid. Dose response testing was performed in three to four groups of male mice from each strain. Following kainate injections, mice were scored for seizure activity and brains from mice in each age group were processed for light microscopic histopathologic evaluation 7 days following kainate administration to evaluate the severity of seizure-induced brain damage. Irrespective of the dose of kainate administered or the age group examined, resistant strains of mice (C57BL/6J) continued to be resistant to seizure-induced cell death. In contrast, aged animals of the FVB/NJ strain were more vulnerable to the induction of behavioral seizures and associated neuropathology after systemic injection of kainic acid than young or middle-aged mice. Results from these studies suggest that the age-related increased susceptibility to the neurotoxic effects of seizure induction and seizure-induced injury is regulated in a strain-dependent manner, similar to previous observations in young adult mice.
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Affiliation(s)
- M C McCord
- Department of Cell and Neurobiology, Keck School of Medicine of the University of Southern California, BMT 403, 1333 San Pablo Street, Los Angeles, CA 90089, USA
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Zhang XM, Zhu SW, Duan RS, Mohammed AH, Winblad B, Zhu J. Gender differences in susceptibility to kainic acid-induced neurodegeneration in aged C57BL/6 mice. Neurotoxicology 2008; 29:406-12. [PMID: 18342945 DOI: 10.1016/j.neuro.2008.01.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Revised: 01/10/2008] [Accepted: 01/29/2008] [Indexed: 11/15/2022]
Abstract
Some epidemiological studies concerning gender differences in Alzheimer's disease (AD) support the higher prevalence and incidence of AD in women, while most studies using animal models of aging have included only male subjects. It is still uncommon for aged males and females to be compared in the same study. In the present study, we investigated how age and gender influence the excitotoxic neurodegeneration by treating C57BL/6 mice (aged females and males as well as adult females and males) with kainic acid (KA) intranasally. Clinical signs, behavioural changes, pathological changes and astrocyte proliferation were tested; and the levels of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) were measured after KA treatment. The results showed that aged female mice were more sensitive to KA-induced excitotoxicity as demonstrated by severer seizure activity, increased locomotion and rearing in open-field test, prominent hippocampal neuronal damage, enhanced astrocyte proliferation compared with aged males, adult females and adult male mice. In addition, higher BDNF level in hippocampus of aged female mice was observed. These results denote the disparity of aging and gender in KA-induced hippocampal neurodegeneration and aged female mice are more sensitive to the excitotoxicity.
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Affiliation(s)
- Xing-Mei Zhang
- Department of Neurobiology, Care Sciences and Society, Karolinska Institute, Stockholm, Sweden
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19
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Abstract
Hormesis is defined operationally as responses of cells or organisms to an exogenous or intrinsic factor (chemical, temperature, psychological challenge, etc.) in which the factor induces stimulatory or beneficial effects at low doses and inhibitory or adverse effects at high doses. The compendium of articles by Calabrese entitled "Neuroscience and Hormesis" provides a broad range of examples of neurobiological processes and responses to environmental factors that exhibit biphasic dose responses, the signature of hormesis. Nerve cell networks are the "first responders" to environmental challenges--they perceive the challenge and orchestrate coordinated adaptive responses that typically involve autonomic, neuroendocrine, and behavioral changes. In addition to direct adaptive responses of neurons to environmental stressors, cells subjected to a stressor produce and release molecules such as growth factors, cytokines, and hormones that alert adjacent and even distant cells to impending danger. The discoveries that some molecules (e.g., carbon monoxide and nitric oxide) and elements (e.g., selenium and iron) that are toxic at high doses play fundamental roles in cellular signaling or metabolism suggest that during evolution, organisms (and their nervous systems) co-opted environmental toxins and used them to their advantage. Neurons also respond adaptively to everyday stressors, including physical exercise, cognitive challenges, and dietary energy restriction, each of which activates pathways linked to the production of neurotrophic factors and cellular stress resistance proteins. The development of interventions that activate hormetic signaling pathways in neurons is a promising new approach for the preventation and treatment of a range of neurological disorders.
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Affiliation(s)
- Mark P Mattson
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, Maryland 21224, USA.
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20
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Takeda A, Sakurada N, Kanno S, Ando M, Oku N. Vulnerability to Seizures Induced by Potassium Dyshomeostasis in the Hippocampus in Aged Rats. ACTA ACUST UNITED AC 2008. [DOI: 10.1248/jhs.54.37] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Atsushi Takeda
- Department of Medical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka
| | - Naomi Sakurada
- Department of Medical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka
| | - Shingo Kanno
- Department of Medical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka
| | - Masaki Ando
- Department of Medical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka
| | - Naoto Oku
- Department of Medical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka
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21
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Sawant PM, Weare BA, Holland PT, Selwood AI, King KL, Mikulski CM, Doucette GJ, Mountfort DO, Kerr DS. Isodomoic acids A and C exhibit low KA receptor affinity and reduced in vitro potency relative to domoic acid in region CA1 of rat hippocampus. Toxicon 2007; 50:627-38. [PMID: 17640694 DOI: 10.1016/j.toxicon.2007.05.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2007] [Revised: 05/16/2007] [Accepted: 05/29/2007] [Indexed: 11/29/2022]
Abstract
Several natural isomers of the seizurogenic neurotoxin domoic acid (DA) have been found to occur at up to mg/kg levels in shellfish. The aim of the current study was to assess the neurotoxic potency of isodomoic acids A and C (Iso-A and Iso-C), recently isolated from commercial shellfish. Hippocampal slices were obtained from young adult rats and maintained in a tissue recording chamber. Synaptically evoked population spikes were recorded in region CA1 before and after exposure to DA or its isomers. Both Iso-A and Iso-C produced transient neuronal hyperexcitability followed by a dose-dependent suppression of population spikes, but were, respectively, 4- and 20-fold less potent than DA (spike area: EC50 DA=237 nM; Iso-A=939 nM; Iso-C=4.6 microM). In the hippocampus, DA preconditioning induces tolerance to subsequent DA toxicity. However, in the present study neither Iso-A nor Iso-C were effective as preconditioning agents. Competitive binding studies using homomeric GluR6 kainate (kainic acid, KA) receptors showed the affinity of Iso-A to be 40-fold lower than DA (Ki DA=3.35 nM; Iso-A=130 nM). Together with earlier work showing Iso-C affinity at GluR6 receptors to be 240-fold lower than DA, our results suggest that neuroexcitatory effects of Iso-A in CA1 may involve both alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) and KA receptors, while Iso-C likely involves the activation of AMPA receptors alone.
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Affiliation(s)
- P M Sawant
- Department of Pharmacology and Toxicology, University of Otago School of Medical Sciences, P.O. Box 913, Dunedin, New Zealand
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22
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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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23
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Mattson MP, Cheng A. Neurohormetic phytochemicals: Low-dose toxins that induce adaptive neuronal stress responses. Trends Neurosci 2006; 29:632-9. [PMID: 17000014 DOI: 10.1016/j.tins.2006.09.001] [Citation(s) in RCA: 213] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Revised: 07/25/2006] [Accepted: 09/15/2006] [Indexed: 12/16/2022]
Abstract
Diets rich in vegetables and fruits are associated with reduced risk of several major diseases, including neurodegenerative disorders. Although some beneficial phytochemicals might function solely as antioxidants, it is becoming clear that many of the beneficial chemicals in vegetables and fruits evolved as toxins (to dissuade insects and other predators) that, at subtoxic doses, activate adaptive cellular stress-response pathways in a variety of cells including neurons. Examples of such 'preconditioning' or 'neurohormesis' pathways include those involving cell-survival signaling kinases, the transcription factors NRF2 and CREB, and histone deacetylases of the sirtuin family. In these ways, neurohormetic phytochemicals such as resveratrol, sulforaphanes and curcumin might protect neurons against injury and disease by stimulating the production of antioxidant enzymes, neurotrophic factors, protein chaperones and other proteins that help cells to withstand stress. Thus, as we discuss in this review, highly conserved longevity and survival pathways in neurons are the targets of many phytochemicals.
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Affiliation(s)
- Mark P Mattson
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224, USA.
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24
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Leppik IE, Kelly KM, deToledo-Morrell L, Patrylo PR, DeLorenzo RJ, Mathern GW, White HS. Basic research in epilepsy and aging. Epilepsy Res 2005; 68 Suppl 1:S21-37. [PMID: 16384687 DOI: 10.1016/j.eplepsyres.2005.07.014] [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] [Received: 05/05/2005] [Revised: 07/27/2005] [Accepted: 07/27/2005] [Indexed: 10/25/2022]
Abstract
A PubMed search of the years 1965 to 2003 found only 30 articles that were directly related to modeling seizures or epilepsy in aged animals. This lack of research is disturbing but explainable because of the high cost of aged animals and their increasing infirmity. Many changes occur in the older brain: cell loss in the hippocampal formation, changes in long-term potentiation maintenance, alteration in kindling, increased susceptibility to status epilepticus, and neuronal damage from stroke. The effect of aging on voltage-gated sodium and calcium channels has not been studied sufficiently. With increasing numbers of elderly persons with epilepsy needing appropriate treatment, the need to better understand the basic mechanisms of epilepsy is crucial.
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Affiliation(s)
- Ilo E Leppik
- College of Pharmacy, University of Minnesota, 308 Harvard St. SE, Minneapolis, MN 55455, USA.
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25
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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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26
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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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27
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Hoedemaker JR, Peake BM, Kerr DS. Reduction in functional potency of the neurotoxin domoic acid in the presence of cadmium and zinc ions. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2005; 20:175-181. [PMID: 21783586 DOI: 10.1016/j.etap.2004.12.061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2004] [Accepted: 12/13/2004] [Indexed: 05/31/2023]
Abstract
The tricarboxylic neurotoxin domoic acid (DA) binds trace metals such as iron and copper. In vitro brain slice recording (area CA1 of rat hippocampal slices) was used to assess changes in DA potency in the presence of cadmium and zinc. Cadmium or zinc alone had little or no effect on CA1 responses. DA alone produced hyperexcitability and, with prolonged administration, a robust suppression of CA1 responses. Coadministration of DA with either 2 or 4μM Cd(2+) produced significant reductions in the potency of DA; less striking effects were seen in the presence of 4μM Zn(2+). These findings suggest that interactions of Cd(2+) and Zn(2+) with DA result in the formation of trace metal-neurotoxin complexes which are either unavailable for binding to ionotropic glutamate receptors, or bind without producing full agonist activity.
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Affiliation(s)
- José R Hoedemaker
- Department of Pharmacology and Toxicology, University of Otago School of Medical Sciences, P.O. Box 913, Dunedin, New Zealand; Department of Chemistry, University of Otago, P.O. Box 56, Dunedin, New Zealand
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28
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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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29
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Darbin O, Naritoku D, Patrylo PR. Aging alters electroencephalographic and clinical manifestations of kainate-induced status epilepticus. Epilepsia 2004; 45:1219-27. [PMID: 15461676 DOI: 10.1111/j.0013-9580.2004.66103.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE The elderly exhibit an increased risk for developing status epilepticus and status-related morbidity and mortality. However, it is unclear how aging alters the progression of electroencephalographic (EEG) activity and behavioral manifestations during status epilepticus. METHODS A repetitive low-dose kainate treatment protocol (2.5 mg/kg/h; i.p.) was used in this study in conjunction with EEG and behavioral monitoring from freely behaving adult (7-8 months) and aged (22-25 months) Fischer 344 rats to assess the effects of aging on status epilepticus. RESULTS During kainate treatment, both groups exhibited an increase in EEG power that corresponded with the time course of kainate treatment. However, visual inspection and spectral analysis revealed a reduction of the faster frequencies (12.5-35 Hz) in the EEGs of aged rodents. A similar progression of behavioral manifestations was observed in adult and aged rodents during kainate treatment, although the frequency of preseizure manifestations (e.g., wet-dog shakes; aged rats, 110 events/h vs. adults, 25 events/h; median values) was greater, and latency to onset for any given behavioral manifestation (e.g., class V seizures; aged median, 60 min, vs. adult median, 145 min) was consistently shorter within the aged group. CONCLUSIONS These data reveal that aged Fischer 344 rats exhibit altered EEG activity (reduction of higher frequencies) and clinical manifestations during kainate-induced status epilepticus. Taken together, these data indicate an age-related change in seizure onset and spread after exposure to glutamate analogues.
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Affiliation(s)
- Olivier Darbin
- Department of Physiology, Southern Illinois University School of Medicine, Carbondale, Illinois 62901, USA
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30
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Hesp BR, Wrightson T, Mullaney I, Kerr DS. Kainate receptor agonists and antagonists mediate tolerance to kainic acid and reduce high-affinity GTPase activity in young, but not aged, rat hippocampus. J Neurochem 2004; 90:70-9. [PMID: 15198668 DOI: 10.1111/j.1471-4159.2004.02469.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Domoic acid acts at both kainic acid (KA) and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)-sensitive glutamate receptors and induces tolerance against subsequent domoic acid insult in young but not aged rat hippocampus. To determine the receptor specificity of this effect, tolerance induction was examined in hippocampal slices from young and aged rats. Slices were preconditioned by exposure to low-dose KA to activate kainate receptors, or the AMPA-receptor selective agonist (S)-5-fluorowillardiine (FW), and following washout, tolerance induction was assessed by administration of high concentrations of KA or FW (respectively). FW preconditioning failed to induce tolerance to subsequent FW challenges, while KA-preconditioned slices were significantly resistant to the effects of high-dose KA. KA preconditioning failed to induce tolerance in aged CA1. Given the lasting nature of the tolerance effect, we examined G-protein-coupled receptor function. A number of ionotropic KA receptor agonists and antagonists significantly reduced constitutive GTPase activity in hippocampal membranes from young but not aged rats. Furthermore, in young CA1, low concentrations of the AMPA/KA blocker GYKI-52466 also induced tolerance to high-dose KA. Our findings suggest that tolerance is triggered by a selective reduction in constitutive KA-sensitive G-protein activity, and that this potential neuroprotective mechanism is lost with age.
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Affiliation(s)
- Blair R Hesp
- Department of Pharmacology and Toxicology, University of Otago School of Medical Sciences, Dunedin, New Zealand
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31
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Stanley DP, Shetty AK. Aging in the rat hippocampus is associated with widespread reductions in the number of glutamate decarboxylase-67 positive interneurons but not interneuron degeneration. J Neurochem 2004; 89:204-16. [PMID: 15030405 DOI: 10.1111/j.1471-4159.2004.02318.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Increased excitability of principal excitatory neurons is one of the hallmarks of aging in the hippocampus, signifying a diminution in the number and/or function of inhibitory interneurons with aging. To elucidate this, we performed comprehensive GABA-ergic interneuron cell counts in all layers of the dentate gyrus and the CA1 and CA3 subfields, using serial sections from adult, middle-aged and aged Fischer 344 rats. Sections were immunostained for glutamate decarboxylase-67 (GAD-67, a synthesizing enzyme of GABA) and GAD-67 immunopositive interneurons were counted using an unbiased cell counting method, the optical fractionator. Substantial declines in the absolute number of GAD-67 immunopositive interneurons were found in all hippocampal layers/subfields of middle-aged and aged animals, in comparison with the adult animals. However, the counts were comparable between the middle-aged and aged groups for all regions. Interestingly, determination of the absolute number of interneurons using neuron-specific nuclear antigen (NeuN) expression in the strata oriens and radiatum of CA1 and CA3 subfields revealed an analogous number of interneurons across the three age groups. Furthermore, the ratio of GAD-67 immunopositive and NeuN positive interneurons decreased from adult age to middle age but remained relatively static between middle age and old age. Collectively, the results underscore that aging in the hippocampus is associated with wide-ranging decreases in the number of GAD-67 immunopositive interneurons and most of the age-related changes in GAD-67 immunopositive interneuron numbers transpire by middle age. Additionally, this study provides novel evidence that age-related reductions in hippocampal GAD-67 immunopositive interneuron numbers are due to loss of GAD-67 expression in interneurons rather than interneuron degeneration.
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Affiliation(s)
- Dirk P Stanley
- Medical Research Service, Veterans Affairs Medical Center, Durham, North Carolina 27710, USA.
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Abstract
PURPOSE OF REVIEW In recent times the number of blooms of algae that produce toxins has increased in frequency, intensity and geographical distribution. This review describes some of the illnesses caused by fish and shellfish contaminated with toxins produced by marine algae and by bacteria. RECENT FINDINGS The increase in toxic algal blooms may be a result of increased awareness, aquaculture, eutrophication, or transport of cysts in ship ballast. Improved chemical methods for the detection of algal toxins are now being developed, and so the number of toxins recognized is increasing. Toxicological data on some of these algal toxins are lacking. Despite the increase in occurrence of algal toxins, scombrotoxic poisoning remains the most common cause of food poisoning associated with the consumption of fish and shellfish. This may be real or it may be a reflection of lack of suitable tests for algal toxins or under-recognition by workers in health care. SUMMARY The major problem worldwide in this field is the lack of pure toxins for use in developing and standardizing chemical methods for toxin detection. Such methods would permit increased testing of both food and clinical specimens, and hence would prevent the entry of toxic food into the food chain and increase laboratory confirmation of incidents of illness.
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Affiliation(s)
- Moira M Brett
- Division of Gastrointestinal Infection, Health Protection Agency Central Public Health Laboratory, London, UK
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Zheng Y, Kerr DS, Darlington CL, Smith PF. Unilateral inner ear damage results in lasting changes in hippocampal CA1 field potentials in vitro. Hippocampus 2003; 13:873-8. [PMID: 14750650 DOI: 10.1002/hipo.10174] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We investigated the effects of a surgical lesion of one vestibular inner ear (unilateral vestibular damage [UVD]) on the field potential responses of CA1 neurons in vitro. Hippocampal slices were removed from rats at 4-6 weeks or 5-6 months post-UVD, and the field responses of CA1 neurons to electrical stimulation of the Schaffer collateral commissural pathway were analyzed. Compared with slices from sham and naive control animals, slices from UVD animals at 5-6 months post-UVD exhibited decreases in the population spike amplitude, the somal field excitatory postsynaptic potential (sfEPSP) slope, and the field EPSP (fEPSP) slope. For the population spike amplitude and fEPSP slope, this effect was observed in both CA1 ipsilateral and contralateral to the UVD. On both the ipsilateral and contralateral sides, paired-pulse testing showed increases in paired-pulse inhibition at the shortest interstimulus intervals (ISIs), with increases in paired-pulse facilitation at longer ISIs. This study provides the first evidence that peripheral vestibular damage can produce long-term changes in hippocampal electrophysiological activity in vitro.
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Affiliation(s)
- Yiwen Zheng
- Department of Pharmacology and Toxicology, School of Medical Sciences, University of Otago, Dunedin, New Zealand
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