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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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Thomsen MB, Jacobsen J, Lillethorup TP, Schacht AC, Simonsen M, Romero-Ramos M, Brooks DJ, Landau AM. In vivo imaging of synaptic SV2A protein density in healthy and striatal-lesioned rats with [11C]UCB-J PET. J Cereb Blood Flow Metab 2021; 41:819-830. [PMID: 32538280 PMCID: PMC7983510 DOI: 10.1177/0271678x20931140] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 04/30/2020] [Accepted: 05/05/2020] [Indexed: 12/30/2022]
Abstract
The number of functionally active synapses provides a measure of neural integrity, with reductions observed in neurodegenerative disorders. [11C]UCB-J binds to synaptic vesicle 2A (SV2A) transmembrane protein located in secretory vesicles. We aimed to assess [11C]UCB-J PET as an in vivo biomarker of regional cerebral synaptic SV2A density in rat lesion models of neurodegeneration. Healthy anesthetized rats had [11C]UCB-J PET and arterial blood sampling. We compared different models describing [11C]UCB-J brain uptake kinetics to determine its regional distribution. Blocking studies were performed with levetiracetam (LEV), an antiepileptic SV2A antagonist. Tracer binding was measured in rodent unilateral acute lesion models of Parkinsonism and Huntington's disease, induced with 6-hydroxydopamine (6-OHDA) and quinolinic acid (QA), respectively. [3H]UCB-J autoradiography was performed in postmortem tissue. Rat brain showed high and fast [11C]UCB-J uptake and washout with up to 80% blockade by LEV. [11C]UCB-J PET showed a 6.2% decrease in ipsilateral striatal SV2A binding after 6-OHDA and 39.3% and 55.1% decreases after moderate and high dose QA confirmed by autoradiography. In conclusion, [11C]UCB-J PET provides a good in vivo marker of synaptic SV2A density which can potentially be followed longitudinally along with synaptic responses to putative neuroprotective agents in models of neurodegeneration.
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Affiliation(s)
- Majken B Thomsen
- Department of Nuclear Medicine and PET Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Jan Jacobsen
- Department of Nuclear Medicine and PET Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Thea P Lillethorup
- Department of Nuclear Medicine and PET Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Anna C Schacht
- Department of Nuclear Medicine and PET Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Mette Simonsen
- Department of Nuclear Medicine and PET Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | | | - David J Brooks
- Department of Nuclear Medicine and PET Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- Translational and Clinical Research Institute, Newcastle upon Tyne University, Newcastle upon Tyne, UK
| | - Anne M Landau
- Department of Nuclear Medicine and PET Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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Thomsen MB, Schacht AC, Alstrup AKO, Jacobsen J, Lillethorup TP, Bærentzen SL, Noer O, Orlowski D, Elfving B, Müller HK, Brooks DJ, Landau AM. Preclinical PET Studies of [ 11C]UCB-J Binding in Minipig Brain. Mol Imaging Biol 2020; 22:1290-1300. [PMID: 32514885 DOI: 10.1007/s11307-020-01506-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PURPOSE Loss of neuronal synapse function is associated with a number of brain disorders. The [11C]UCB-J positron emission tomography (PET) tracer allows for in vivo examination of synaptic density, as it binds to synaptic vesicle glycoprotein 2A (SV2A) expressed in presynaptic terminals. Here, we characterise [11C]UCB-J imaging in Göttingen minipigs. PROCEDURES Using PET imaging, we examined tracer specificity and compared kinetic models. We explored the use of a standard blood curve and centrum semiovale white matter as a reference region. We compared in vivo [11C]UCB-J PET imaging to in vitro autoradiography, Western blotting and real-time quantitative polymerase chain reaction. RESULTS The uptake kinetics of [11C]UCB-J could be described using a 1-tissue compartment model and blocking of SV2A availability with levetiracetam showed dose-dependent specific binding. Population-based blood curves resulted in reliable [11C]UCB-J binding estimates, while it was not possible to use centrum semiovale white matter as a non-specific reference region. Brain [11C]UCB-J PET signals correlated well with [3H]UCB-J autoradiography and SV2A protein levels. CONCLUSIONS [11C]UCB-J PET is a valid in vivo marker of synaptic density in the minipig brain, with binding values close to those reported for humans. Minipig models of disease could be valuable for investigating the efficacy of putative neuroprotective agents for preserving synaptic function in future non-invasive, longitudinal studies.
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Affiliation(s)
- Majken Borup Thomsen
- Department of Nuclear Medicine and PET, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 165, J, 8200, Aarhus N, Denmark
| | - Anna Christina Schacht
- Department of Nuclear Medicine and PET, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 165, J, 8200, Aarhus N, Denmark
| | - Aage Kristian Olsen Alstrup
- Department of Nuclear Medicine and PET, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 165, J, 8200, Aarhus N, Denmark
| | - Jan Jacobsen
- Department of Nuclear Medicine and PET, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 165, J, 8200, Aarhus N, Denmark
| | - Thea Pinholt Lillethorup
- Department of Nuclear Medicine and PET, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 165, J, 8200, Aarhus N, Denmark
| | - Simone Larsen Bærentzen
- Department of Nuclear Medicine and PET, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 165, J, 8200, Aarhus N, Denmark.,Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Ove Noer
- Department of Nuclear Medicine and PET, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 165, J, 8200, Aarhus N, Denmark
| | - Dariusz Orlowski
- Center for Experimental Neuroscience (CENSE), Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Betina Elfving
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Heidi Kaastrup Müller
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - David J Brooks
- Department of Nuclear Medicine and PET, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 165, J, 8200, Aarhus N, Denmark.,Institute of Translational and Clinical Research, Faculty of Medical Science, Newcastle upon Tyne University, Newcastle upon Tyne, UK
| | - Anne M Landau
- Department of Nuclear Medicine and PET, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 165, J, 8200, Aarhus N, Denmark. .,Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
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Radioligand binding analysis of α 2 adrenoceptors with [ 11C]yohimbine in brain in vivo: Extended Inhibition Plot correction for plasma protein binding. Sci Rep 2017; 7:15979. [PMID: 29167492 PMCID: PMC5700124 DOI: 10.1038/s41598-017-16020-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 10/23/2017] [Indexed: 11/23/2022] Open
Abstract
We describe a novel method of kinetic analysis of radioligand binding to neuroreceptors in brain in vivo, here applied to noradrenaline receptors in rat brain. The method uses positron emission tomography (PET) of [11C]yohimbine binding in brain to quantify the density and affinity of α2 adrenoceptors under condition of changing radioligand binding to plasma proteins. We obtained dynamic PET recordings from brain of Spraque Dawley rats at baseline, followed by pharmacological challenge with unlabeled yohimbine (0.3 mg/kg). The challenge with unlabeled ligand failed to diminish radioligand accumulation in brain tissue, due to the blocking of radioligand binding to plasma proteins that elevated the free fractions of the radioligand in plasma. We devised a method that graphically resolved the masking of unlabeled ligand binding by the increase of radioligand free fractions in plasma. The Extended Inhibition Plot introduced here yielded an estimate of the volume of distribution of non-displaceable ligand in brain tissue that increased with the increase of the free fraction of the radioligand in plasma. The resulting binding potentials of the radioligand declined by 50–60% in the presence of unlabeled ligand. The kinetic unmasking of inhibited binding reflected in the increase of the reference volume of distribution yielded estimates of receptor saturation consistent with the binding of unlabeled ligand.
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