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Kisby GE, Eriksen JL, Chlebowski AC, Spencer PS. Cycad Genotoxin Methylazoxymethanol Disrupts the Brain Ubiquitin-Proteasome Pathway, Tau and α-Synuclein, as Reported in ALS-PDC. J Neuropathol Exp Neurol 2021; 80:286-288. [PMID: 33550390 PMCID: PMC8786491 DOI: 10.1093/jnen/nlab006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Affiliation(s)
- Glen E Kisby
- Pharmacology, Western University for Health Sciences, Lebanon, Oregon, USA
| | | | - Anna C Chlebowski
- Pharmacology, Western University for Health Sciences, Lebanon, Oregon, USA
| | - Peter S Spencer
- Neurology, School of Medicine and Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, Oregon, USA
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Chernoff N, Hill DJ, Diggs DL, Faison BD, Francis BM, Lang JR, Larue MM, Le TT, Loftin KA, Lugo JN, Schmid JE, Winnik WM. A critical review of the postulated role of the non-essential amino acid, β-N-methylamino-L-alanine, in neurodegenerative disease in humans. J Toxicol Environ Health B Crit Rev 2017; 20:1-47. [PMID: 28598725 PMCID: PMC6503681 DOI: 10.1080/10937404.2017.1297592] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The compound BMAA (β-N-methylamino-L-alanine) has been postulated to play a significant role in four serious neurological human diseases: Amyotrophic Lateral Sclerosis/Parkinsonism Dementia Complex (ALS/PDC) found on Guam, and ALS, Parkinsonism, and dementia that occur globally. ALS/PDC with symptoms of all three diseases first came to the attention of the scientific community during and after World War II. It was initially associated with cycad flour used for food because BMAA is a product of symbiotic cycad root-dwelling cyanobacteria. Human consumption of flying foxes that fed on cycad seeds was later suggested as a source of BMAA on Guam and a cause of ALS/PDC. Subsequently, the hypothesis was expanded to include a causative role for BMAA in other neurodegenerative diseases including Alzheimer's disease (AD) through exposures attributed to proximity to freshwaters and/or consumption of seafood due to its purported production by most species of cyanobacteria. The hypothesis that BMAA is the critical factor in the genesis of these neurodegenerative diseases received considerable attention in the medical, scientific, and public arenas. This review examines the history of ALS/PDC and the BMAA-human disease hypotheses; similarities and differences between ALS/PDC and the other diseases with similar symptomologies; the relationship of ALS/PDC to other similar diseases, studies of BMAA-mediated effects in lab animals, inconsistencies and data gaps in the hypothesis; and other compounds and agents that were suggested as the cause of ALS/PDC on Guam. The review concludes that the hypothesis of a causal BMAA neurodegenerative disease relationship is not supported by existing data.
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Affiliation(s)
- N. Chernoff
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Research Triangle Park, NC, USA
| | - D. J. Hill
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Research Triangle Park, NC, USA
| | - D. L. Diggs
- Oak Ridge Institute for Science and Education Internship/Research Participation Program at the U.S. Environmental Protection Agency, NHEERL, Research Triangle Park, NC, USA
| | - B. D. Faison
- U.S. Environmental Protection Agency, Office of Water, Office of Science and Technology, Washington, DC, USA
| | - B. M. Francis
- Department of Entomology, University of Illinois, Champaign-Urbana, IL, USA
| | - J. R Lang
- Oak Ridge Institute for Science and Education Internship/Research Participation Program at the U.S. Environmental Protection Agency, NHEERL, Research Triangle Park, NC, USA
| | - M. M. Larue
- Oak Ridge Institute for Science and Education Internship/Research Participation Program at the U.S. Environmental Protection Agency, NHEERL, Research Triangle Park, NC, USA
| | - T.-T. Le
- Oak Ridge Institute for Science and Education Internship/Research Participation Program at the U.S. Environmental Protection Agency, NHEERL, Research Triangle Park, NC, USA
| | | | - J. N. Lugo
- Department of Psychology and Neuroscience, Baylor University, Waco, TX, USA
| | - J. E. Schmid
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Research Triangle Park, NC, USA
| | - W. M. Winnik
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Research Triangle Park, NC, USA
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Kisby GE, Moore H, Spencer PS. Animal models of brain maldevelopment induced by cycad plant genotoxins. Birth Defects Res C Embryo Today 2013; 99:247-55. [PMID: 24339036 PMCID: PMC4183057 DOI: 10.1002/bdrc.21052] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 10/24/2013] [Indexed: 01/12/2023]
Abstract
Cycads are long-lived tropical and subtropical plants that contain azoxyglycosides (e.g., cycasin, macrozamin) and neurotoxic amino acids (notably β-N-methylamino-l-alanine l-BMAA), toxins that have been implicated in the etiology of a disappearing neurodegenerative disease, amyotrophic lateral sclerosis and parkinsonism-dementia complex that has been present in high incidence among three genetically distinct populations in the western Pacific. The neuropathology of amyotrophic lateral sclerosis/parkinsonism-dementia complex includes features suggestive of brain maldevelopment, an experimentally proven property of cycasin attributable to the genotoxic action of its aglycone methylazoxymethanol (MAM). This property of MAM has been exploited by neurobiologists as a tool to study perturbations of brain development. Depending on the neurodevelopmental stage, MAM can induce features in laboratory animals that model certain characteristics of epilepsy, schizophrenia, or ataxia. Studies in DNA repair-deficient mice show that MAM perturbs brain development through a DNA damage-mediated mechanism. The brain DNA lesions produced by systemic MAM appear to modulate the expression of genes that regulate neurodevelopment and contribute to neurodegeneration. Epigenetic changes (histone lysine methylation) have also been detected in the underdeveloped brain after MAM administration. The DNA damage and epigenetic changes produced by MAM and, perhaps by chemically related substances (e.g., nitrosamines, nitrosoureas, hydrazines), might be an important mechanism by which early-life exposure to genotoxicants can induce long-term brain dysfunction.
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Affiliation(s)
- Glen E. Kisby
- Department of Basic Medical Sciences, Western University of Health Sciences, College of Osteopathic Medicine of the Pacific Northwest, Lebanon, Oregon, 97355
| | - Holly Moore
- Department of Psychiatry, Columbia University and Department of Integrative Neuroscience, New York State Psychiatric Institute, New York, NY
| | - Peter S. Spencer
- Department of Neurology, School of Medicine, Center for Research on Occupational and Environmental Toxciology; and Global Health Center, Oregon Health and Science University, Portland, Oregon, 97201
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McDowell KA, Hadjimarkou MM, Viechweg S, Rose AE, Clark SM, Yarowsky PJ, Mong JA. Sleep alterations in an environmental neurotoxin-induced model of parkinsonism. Exp Neurol 2010; 226:84-9. [PMID: 20713046 DOI: 10.1016/j.expneurol.2010.08.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2010] [Revised: 07/16/2010] [Accepted: 08/10/2010] [Indexed: 11/18/2022]
Abstract
Parkinson's disease (PD) is classically defined as a motor disorder resulting from decreased dopamine production in the basal ganglia circuit. In an attempt to better diagnose and treat PD before the onset of severe motor dysfunction, recent attention has focused on the early, non-motor symptoms, which include but are not limited to sleep disorders such as excessive daytime sleepiness (EDS) and REM behavioral disorder (RBD). However, few animal models have been able to replicate both the motor and non-motor symptoms of PD. Here, we present a progressive rat model of parkinsonism that displays disturbances in sleep/wake patterns. Epidemiological studies elucidated a link between the Guamanian variant of Amyotrophic Lateral Sclerosis/Parkinsonism Dementia Complex (ALS/PDC) and the consumption of flour made from the washed seeds of the plant Cycas micronesica (cycad). Our study examined the effects of prolonged cycad consumption on sleep/wake activity in male, Sprague-Dawley rats. Cycad-fed rats exhibited an increase in length and/or number of bouts of rapid eye movement (REM) sleep and Non-REM (NREM) sleep at the expense of wakefulness during the active period when compared to control rats. This hypersomnolent behavior suggests an inability to maintain arousal. In addition, cycad-fed rats had significantly fewer orexin cells in the hypothalamus. Our results reveal a novel rodent model of parkinsonism that includes an EDS-like syndrome that may be associated with a dysregulation of orexin neurons. Further characterization of this early, non-motor symptom, may provide potential therapeutic interventions in the treatment of PD.
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Affiliation(s)
- Kimberly A McDowell
- Program in Neuroscience, University of Maryland, School of Medicine, Baltimore, MD, USA
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Shen WB, McDowell KA, Siebert AA, Clark SM, Dugger NV, Valentino KM, Jinnah HA, Sztalryd C, Fishman PS, Shaw CA, Jafri MS, Yarowsky PJ. Environmental neurotoxin-induced progressive model of parkinsonism in rats. Ann Neurol 2010; 68:70-80. [PMID: 20582986 PMCID: PMC2988442 DOI: 10.1002/ana.22018] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Exposure to a number of drugs, chemicals, or environmental factors can cause parkinsonism. Epidemiologic evidence supports a causal link between the consumption of flour made from the washed seeds of the plant Cycas micronesica by the Chamorro population of Guam and the development of amyotrophic lateral sclerosis/parkinsonism dementia complex. METHODS We now report that consumption of washed cycad flour pellets by Sprague-Dawley male rats induces progressive parkinsonism. RESULTS Cycad-fed rats displayed motor abnormalities after 2 to 3 months of feeding such as spontaneous unilateral rotation, shuffling gait, and stereotypy. Histological and biochemical examination of brains from cycad-fed rats revealed an initial decrease in the levels of dopamine and its metabolites in the striatum (STR), followed by neurodegeneration of dopaminergic (DAergic) cell bodies in the substantia nigra (SN) pars compacta (SNc). alpha-Synuclein (alpha-syn; proteinase K-resistant) and ubiquitin aggregates were found in the DAergic neurons of the SNc and neurites in the STR. In addition, we identified alpha-syn aggregates in neurons of the locus coeruleus and cingulate cortex. No loss of motor neurons in the spinal cord was found after chronic consumption of cycad flour. In an organotypic slice culture of the rat SN and the striatum, an organic extract of cycad causes a selective loss of dopamine neurons and alpha-syn aggregates in the SN. INTERPRETATION Cycad-fed rats exhibit progressive behavioral, biochemical, and histological hallmarks of parkinsonism, coupled with a lack of fatality.
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Affiliation(s)
- Wei-Bin Shen
- Department of Pharmacology and Experimental Therapeutics, University of Maryland School of Medicine, 655 W. Baltimore Street, Baltimore, MD 21201, USA
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Abstract
The causal factor(s) responsible for sporadic neurological diseases are unknown and the stages of disease progression remain undefined and poorly understood. We have developed an animal model of amyotrophic lateral sclerosis-parkinsonism dementia complex which mimics all the essential features of the disease with the initial neurological insult arising from neurotoxins contained in washed cycad seeds. Animals fed washed cycad develop deficits in motor, cognitive, and sensory behaviors that correlate with the loss of neurons in specific regions of the central nervous system. The ability to recreate the disease by exposure to cycad allows us to extend the model in multiple dimensions by analyzing behavioral, cellular, and biochemical changes over time. In addition, the ability to induce toxin-based neurodegeneration allows us to probe the interactions between genetic and epigenetic factors. Our results show that the impact of both genetic causal and susceptibility factors with the cycad neurotoxins are complex. The article describes the features of the model and suggests ways that our understanding of cycad-induced neurodegeneration can be used to decipher and identify the early events in various human neurological diseases.
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Affiliation(s)
- C A Shaw
- Program in Neuroscience, University of British Columbia, Vancouver, BC, Canada.
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