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Environmental Neurotoxin β- N-Methylamino-L-alanine (BMAA) as a Widely Occurring Putative Pathogenic Factor in Neurodegenerative Diseases. Microorganisms 2022; 10:microorganisms10122418. [PMID: 36557671 PMCID: PMC9781992 DOI: 10.3390/microorganisms10122418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/28/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022] Open
Abstract
In the present review we have discussed the occurrence of β-N-methylamino-L-alanine (BMAA) and its natural isomers, and the organisms and sample types in which the toxin(s) have been detected. Further, the review discusses general pathogenic mechanisms of neurodegenerative diseases, and how modes of action of BMAA fit in those mechanisms. The biogeography of BMAA occurrence presented here contributes to the planning of epidemiological research based on the geographical distribution of BMAA and human exposure. Analysis of BMAA mechanisms in relation to pathogenic processes of neurodegeneration is used to critically assess the potential significance of the amino acid as well as to identify gaps in our understanding. Taken together, these two approaches provide the basis for the discussion on the potential role of BMAA as a secondary factor in neurodegenerative diseases, the rationale for further research and possible directions the research can take, which are outlined in the conclusions.
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2
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Courtier A, Potheret D, Giannoni P. Environmental bacteria as triggers to brain disease: Possible mechanisms of toxicity and associated human risk. Life Sci 2022; 304:120689. [DOI: 10.1016/j.lfs.2022.120689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 05/11/2022] [Accepted: 06/01/2022] [Indexed: 11/24/2022]
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3
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Zakharova MN, Bakulin IS, Abramova AA. Toxic Damage to Motor Neurons. NEUROCHEM J+ 2021. [DOI: 10.1134/s1819712421040164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Abstract—Amyotrophic lateral sclerosis (ALS) is a multifactor disease in the development of which both genetic and environmental factors play a role. Specifically, the effects of organic and inorganic toxic substances can result in an increased risk of ALS development and the acceleration of disease progression. It was described that some toxins can induce potentially curable ALS-like syndromes. In this case, the specific treatment for the prevention of the effects of the toxic factor may result in positive clinical dynamics. In this article, we review the main types of toxins that can damage motor neurons in the brain and spinal cord leading to the development of the clinical manifestation of ALS, briefly present historical data on studies on the role of toxic substances, and describe the main mechanisms of the pathogenesis of motor neuron disease associated with their action.
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Soto T, Buzzi ED, Rotstein NP, German OL, Politi LE. Damaging effects of BMAA on retina neurons and Müller glial cells. Exp Eye Res 2020; 202:108342. [PMID: 33144094 DOI: 10.1016/j.exer.2020.108342] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 10/23/2020] [Accepted: 10/27/2020] [Indexed: 10/23/2022]
Abstract
B-N-methylamino-L-alanine (BMAA), a cyanotoxin produced by most cyanobacteria, has been proposed to cause long term damages leading to neurodegenerative diseases, including Amyotrophic Lateral Sclerosis/Parkinsonism Dementia complex (ALS/PDC) and retinal pathologies. Previous work has shown diverse mechanisms leading to BMAA-induced degeneration; however, the underlying mechanisms of toxicity affecting retina cells are not fully elucidated. We here show that BMAA treatment of rat retina neurons in vitro induced nuclear fragmentation and cell death in both photoreceptors (PHRs) and amacrine neurons, provoking mitochondrial membrane depolarization. Pretreatment with the N-Methyl-D-aspartate (NMDA) receptor antagonist MK-801 prevented BMAA-induced death of amacrine neurons, but not that of PHRs, implying activation of NMDA receptors participated only in amacrine cell death. Noteworthy, BMAA stimulated a selective axonal outgrowth in amacrine neurons, simultaneously promoting growth cone destabilization. BMAA partially decreased the viability of Müller glial cells (MGC), the main glial cell type in the retina, induced marked alterations in their actin cytoskeleton and impaired their capacity to protect retinal neurons. BMAA also induced cell death and promoted axonal outgrowth in differentiated rat pheochromocytoma (PC12) cells, implying these effects were not limited to amacrine neurons. These results suggest that BMAA is toxic for retina neurons and MGC and point to the involvement of NMDA receptors in amacrine cell death, providing new insight into the mechanisms involved in BMAA neurotoxic effects in the retina.
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Affiliation(s)
- Tamara Soto
- Instituto de Investigaciones Bioquímicas, Depto. de Biología, Bioquímica y Farmacia, Universidad Nacional Del Sur (UNS)-CONICET, 8000, Bahía Blanca, Buenos Aires, Argentina
| | - Edgardo D Buzzi
- Instituto de Investigaciones Bioquímicas, Depto. de Biología, Bioquímica y Farmacia, Universidad Nacional Del Sur (UNS)-CONICET, 8000, Bahía Blanca, Buenos Aires, Argentina; Department of Biology, Biochemistry and Pharmacy, Universidad Nacional Del Sur (UNS)-CONICET, Argentina
| | - Nora P Rotstein
- Instituto de Investigaciones Bioquímicas, Depto. de Biología, Bioquímica y Farmacia, Universidad Nacional Del Sur (UNS)-CONICET, 8000, Bahía Blanca, Buenos Aires, Argentina; Department of Biology, Biochemistry and Pharmacy, Universidad Nacional Del Sur (UNS)-CONICET, Argentina
| | - O Lorena German
- Instituto de Investigaciones Bioquímicas, Depto. de Biología, Bioquímica y Farmacia, Universidad Nacional Del Sur (UNS)-CONICET, 8000, Bahía Blanca, Buenos Aires, Argentina; Department of Biology, Biochemistry and Pharmacy, Universidad Nacional Del Sur (UNS)-CONICET, Argentina
| | - Luis E Politi
- Instituto de Investigaciones Bioquímicas, Depto. de Biología, Bioquímica y Farmacia, Universidad Nacional Del Sur (UNS)-CONICET, 8000, Bahía Blanca, Buenos Aires, Argentina.
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5
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Di Gioia D, Bozzi Cionci N, Baffoni L, Amoruso A, Pane M, Mogna L, Gaggìa F, Lucenti MA, Bersano E, Cantello R, De Marchi F, Mazzini L. A prospective longitudinal study on the microbiota composition in amyotrophic lateral sclerosis. BMC Med 2020; 18:153. [PMID: 32546239 PMCID: PMC7298784 DOI: 10.1186/s12916-020-01607-9] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 04/27/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND A connection between amyotrophic lateral sclerosis (ALS) and altered gut microbiota composition has previously been reported in animal models. This work is the first prospective longitudinal study addressing the microbiota composition in ALS patients and the impact of a probiotic supplementation on the gut microbiota and disease progression. METHODS Fifty patients and 50 matched controls were enrolled. The microbial profile of stool samples from patients and controls was analyzed via PCR-Denaturing Gradient Gel Electrophoresis, and the main microbial groups quantified via qPCR. The whole microbiota was then analyzed via next generation sequencing after amplification of the V3-V4 region of 16S rDNA. Patients were then randomized to receive probiotic treatment or placebo and followed up for 6 months with ALSFRS-R, BMI, and FVC%. RESULTS The results demonstrate that the gut microbiota of ALS patients is characterized by some differences with respect to controls, regardless of the disability degree. Moreover, the gut microbiota composition changes during the course of the disease as demonstrated by the significant decrease in the number of observed operational taxonomic unit during the follow-up. Interestingly, an unbalance between potentially protective microbial groups, such as Bacteroidetes, and other with potential neurotoxic or pro-inflammatory activity, such as Cyanobacteria, has been shown. The 6-month probiotic treatment influenced the gut microbial composition; however, it did not bring the biodiversity of intestinal microbiota of patients closer to that of control subjects and no influence on the progression of the disease measured by ALSFRS-R was demonstrated. CONCLUSIONS Our study poses the bases for larger clinical studies to characterize the microbiota changes as a novel ALS biomarker and to test new microbial strategy to ameliorate the health status of the gut. TRIAL REGISTRATION CE 107/14, approved by the Ethics Committee of the "Maggiore della Carità" University Hospital, Italy.
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Affiliation(s)
- Diana Di Gioia
- Department of Agricultural and Food Sciences, University of Bologna, Viale Fanin 42, Bologna, Italy
| | - Nicole Bozzi Cionci
- Department of Agricultural and Food Sciences, University of Bologna, Viale Fanin 42, Bologna, Italy
| | - Loredana Baffoni
- Department of Agricultural and Food Sciences, University of Bologna, Viale Fanin 42, Bologna, Italy
| | - Angela Amoruso
- BIOLAB RESEARCH srl, via E. Mattei 3, 28100, Novara, Italy
| | - Marco Pane
- BIOLAB RESEARCH srl, via E. Mattei 3, 28100, Novara, Italy
| | - Luca Mogna
- BIOLAB RESEARCH srl, via E. Mattei 3, 28100, Novara, Italy
| | - Francesca Gaggìa
- Department of Agricultural and Food Sciences, University of Bologna, Viale Fanin 42, Bologna, Italy
| | - Maria Ausiliatrice Lucenti
- Department of Neurology and ALS Centre, University of Piemonte Orientale, Maggiore della Carità Hospital, Corso Mazzini 18, 28100, Novara, Italy
| | - Enrica Bersano
- Department of Neurology and ALS Centre, University of Piemonte Orientale, Maggiore della Carità Hospital, Corso Mazzini 18, 28100, Novara, Italy
| | - Roberto Cantello
- Department of Neurology and ALS Centre, University of Piemonte Orientale, Maggiore della Carità Hospital, Corso Mazzini 18, 28100, Novara, Italy
| | - Fabiola De Marchi
- Department of Neurology and ALS Centre, University of Piemonte Orientale, Maggiore della Carità Hospital, Corso Mazzini 18, 28100, Novara, Italy
| | - Letizia Mazzini
- Department of Neurology and ALS Centre, University of Piemonte Orientale, Maggiore della Carità Hospital, Corso Mazzini 18, 28100, Novara, Italy.
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6
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Li A, Espinoza J, Hamdoun A. Inhibitory effects of neurotoxin β-N-methylamino-L-alanine on fertilization and early development of the sea urchin Lytechinus pictus. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2020; 221:105425. [PMID: 32058875 DOI: 10.1016/j.aquatox.2020.105425] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Revised: 01/27/2020] [Accepted: 01/27/2020] [Indexed: 06/10/2023]
Abstract
Neurotoxin β-N-methylamino-L-alanine (BMAA) has been widely detected in diverse aquatic organisms and hypothesized as an environmental risk to neurodegenerative diseases in humans. However, the knowledge of its toxicity to marine organisms requires attention. In the present study, embryos and sperm of the sea urchin, Lytechinus pictus, were used to assess the toxicity of BMAA. Effects of BMAA on fertilization and development of sea urchin embryos were measured, and its impacts on efflux transport of sea urchin blastula were also assayed. Results demonstrated that the fertilization and development of embryos were significantly inhibited by high concentrations of BMAA above 300 μg L-1. The EC50 values indicated by active swimming larvae and total larvae numbers at 96 HPF (hours post fertilization) were 165 μg L-1 (1.4 μmol L-1) and 329 μg L-1 (2.8 μmol L-1), respectively. Additionally, sperm exposed to BMAA for 10 min significantly reduced the fertilization ratio of sea urchin eggs. However, the ABC transport activity on the cytomembrane of sea urchin blastula was not inhibited by the presence of BMAA at 50 μg L-1, even up to 500 μg L-1. Abnormal division and developmental malformations occurred at different developmental stages for sea urchin embryos exposed to BMAA at 500 μg L-1. The inhibitory effects of BMAA on sea urchin embryos were reported at the first time in this study, for which the toxicological mechanisms will be explored in future studies.
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Affiliation(s)
- Aifeng Li
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; Key Laboratory of Marine Environment and Ecology, Ocean University of China, Ministry of Education, Qingdao 266100, China.
| | - Jose Espinoza
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093-0202, USA
| | - Amro Hamdoun
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093-0202, USA
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7
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Diaz-Parga P, Goto JJ, Krishnan VV. On the Differential Roles of Mg 2+, Zn 2+, and Cu 2+ in the Equilibrium of β-N-Methyl-Amino-L-Alanine (BMAA) and its Carbamates. Neurotox Res 2020; 39:6-16. [PMID: 31955368 DOI: 10.1007/s12640-019-00157-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 12/11/2019] [Accepted: 12/19/2019] [Indexed: 12/14/2022]
Abstract
β-N-methyl-amino-L-alanine (BMAA) in the presence of bicarbonate (HCO3-) undergoes structural modifications generating two carbamate species, α-carbamate and β-carbamate forms of BMAA. The chemical structure of BMAA and BMAA-carbamate adducts strongly suggest they may interact with divalent metal ions. The ability of BMAA to cross the blood-brain barrier and possibly interact with divalent metal ions may augment the neurotoxicity of these molecules. To understand the effects of divalent metal ions (Mg2+, Zn2+, and Cu2+) on the overall dynamic equilibrium between BMAA and its carbamate adducts, a systematic study using nuclear magnetic resonance (NMR) is presented. The chemical equilibria between BMAA, its carbamate adducts, and each of the divalent ions were studied using two-dimensional chemical exchange spectroscopy (EXSY). The NMR results demonstrate that BMAA preferentially interacts with Zn2+ and Cu2+, causing an overall reduction in the production of carbamate species by altering the dynamic equilibria. The NMR-based spectral changes due to the BMAA interaction with Cu2+ is more drastic than with the Zn2+, under the same stoichiometric ratios of BMAA and the individual divalent ions. However, the presence of Mg2+ does not significantly alter the dynamic equilibria between BMAA and its carbamate adducts. The NMR-based results are further validated using circular dichroism (CD) spectroscopy, observing the n ➔ π interaction in the complex formation of BMAA and the divalent metal ions, with additional verification of the interaction with Cu2+ using UV-Vis spectroscopy. Our results demonstrate that BMAA differentially interacts with divalent metal ions (Mg2+ < Zn2+ < Cu2+), and thus alters the rate of formation of carbamate products. The equilibria between BMAA, the bicarbonate ions, and the divalent metal ions may alter the total population of a specific form of BMAA-ion complex at physiological conditions and, therefore, add a level of complexity of the mechanisms by which BMAA acts as a neurotoxin.
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Affiliation(s)
- Pedro Diaz-Parga
- Department of Chemistry, California State University, Fresno, CA, 93740, USA
| | - Joy J Goto
- Department of Chemistry, California State University, Fresno, CA, 93740, USA.
| | - V V Krishnan
- Department of Chemistry, California State University, Fresno, CA, 93740, USA. .,Department of Pathology & Laboratory Medicine, University of California Davis, Davis, CA, 95616, USA.
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Manolidi K, Triantis TM, Kaloudis T, Hiskia A. Neurotoxin BMAA and its isomeric amino acids in cyanobacteria and cyanobacteria-based food supplements. JOURNAL OF HAZARDOUS MATERIALS 2019; 365:346-365. [PMID: 30448548 DOI: 10.1016/j.jhazmat.2018.10.084] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 10/26/2018] [Accepted: 10/27/2018] [Indexed: 06/09/2023]
Abstract
Cyanobacteria are photosynthetic microorganisms distributed globally in aquatic and terrestrial environments. They are also industrially cultivated to be used as dietary supplements, as they have a high nutritional value; however, they are also known to produce a wide range of toxic secondary metabolites, called cyanotoxins. BMAA (β-methylamino-l-alanine) and its most common structural isomers, DAB (2,4-diaminobutyric acid) and AEG (N-2-aminoethylglycine) produced by cyanobacteria, are non-proteinogenic amino acids that have been associated with neurodegenerative diseases. A possible route of exposure to those amino acids is through consumption of food supplements based on cyanobacteria. The review critically discusses existing reports regarding the occurrence of BMAA, DAB and AEG in cyanobacteria and cyanobacteria-based food supplements. It is shown that inconsistencies in reported results could be attributed to performance of different methods of extraction and analysis applied and in ambiguities regarding determination of soluble and bound fractions of the compounds. The critical aspect of this review aims to grow awareness of human intake of neurotoxic amino acids, while results presented in literature concerning dietary supplements aim to promote further research, quality control as well as development of guidelines for cyanotoxins in food products.
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Affiliation(s)
- Korina Manolidi
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS", Patriarchou Grigoriou E' & Neapoleos 27, 15341, Athens, Greece; National and Kapodistrian University of Athens, Faculty of Chemistry, 15784, Panepistimiopolis, Athens, Greece.
| | - Theodoros M Triantis
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS", Patriarchou Grigoriou E' & Neapoleos 27, 15341, Athens, Greece.
| | - Triantafyllos Kaloudis
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS", Patriarchou Grigoriou E' & Neapoleos 27, 15341, Athens, Greece; Water Quality Control Department, Athens Water Supply and Sewerage Company - EYDAP SA, Athens, Greece.
| | - Anastasia Hiskia
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS", Patriarchou Grigoriou E' & Neapoleos 27, 15341, Athens, Greece.
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Myhre O, Eide DM, Kleiven S, Utkilen HC, Hofer T. Repeated five-day administration of L-BMAA, microcystin-LR, or as mixture, in adult C57BL/6 mice - lack of adverse cognitive effects. Sci Rep 2018; 8:2308. [PMID: 29396538 PMCID: PMC5797144 DOI: 10.1038/s41598-018-20327-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 01/17/2018] [Indexed: 12/23/2022] Open
Abstract
The cyanobacterial toxins β-methylamino-L-alanine (L-BMAA) and microcystin-LR (MC-LR; a potent liver toxin) are suspected to cause neurological disorders. Adult male C57BL/6JOlaHsd mice aged approximately 11 months were subcutaneously injected for five consecutive days with L-BMAA and microcystin-LR alone, or as a mixture. A dose-range study determined a tolerable daily dose to be ~31 µg MC-LR/kg BW/day based on survival, serum liver status enzymes, and relative liver and kidney weight. Mice tolerating the first one-two doses also tolerated the subsequent three-four doses indicating adaptation. The LD50 was 43-50 μg MC-LR/kg BW. Long-term effects (up to 10 weeks) on spatial learning and memory performance was investigated using a Barnes maze, were mice were given 30 µg MC-LR/kg BW and/or 30 mg L-BMAA/kg BW either alone or in mixture for five consecutive days. Anxiety, general locomotor activity, willingness to explore, hippocampal and peri-postrhinal cortex dependent memory was investigated after eight weeks using Open field combined with Novel location/Novel object recognition tests. Toxin exposed animals did not perform worse than controls, and MC-LR exposed animals performed somewhat better during the first Barnes maze re-test session. MC-LR exposed mice rapidly lost up to ~5% body weight, but regained weight from day eight.
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Affiliation(s)
- Oddvar Myhre
- Department of Toxicology and Risk Assessment, Norwegian Institute of Public Health (NIPH), Oslo, Norway
| | - Dag Marcus Eide
- Department of Toxicology and Risk Assessment, Norwegian Institute of Public Health (NIPH), Oslo, Norway
| | - Synne Kleiven
- Department of Natural Sciences and Environmental Health, University College of Southeast Norway, Bø, Norway
| | - Hans Christian Utkilen
- Department of Natural Sciences and Environmental Health, University College of Southeast Norway, Bø, Norway
| | - Tim Hofer
- Department of Toxicology and Risk Assessment, Norwegian Institute of Public Health (NIPH), Oslo, Norway.
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Scott LL, Downing TG. A Single Neonatal Exposure to BMAA in a Rat Model Produces Neuropathology Consistent with Neurodegenerative Diseases. Toxins (Basel) 2017; 10:E22. [PMID: 29286334 PMCID: PMC5793109 DOI: 10.3390/toxins10010022] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 12/23/2017] [Accepted: 12/27/2017] [Indexed: 12/11/2022] Open
Abstract
Although cyanobacterial β-N-methylamino-l-alanine (BMAA) has been implicated in the development of Alzheimer's Disease (AD), Parkinson's Disease (PD) and Amyotrophic Lateral Sclerosis (ALS), no BMAA animal model has reproduced all the neuropathology typically associated with these neurodegenerative diseases. We present here a neonatal BMAA model that causes β-amyloid deposition, neurofibrillary tangles of hyper-phosphorylated tau, TDP-43 inclusions, Lewy bodies, microbleeds and microgliosis as well as severe neuronal loss in the hippocampus, striatum, substantia nigra pars compacta, and ventral horn of the spinal cord in rats following a single BMAA exposure. We also report here that BMAA exposure on particularly PND3, but also PND4 and 5, the critical period of neurogenesis in the rodent brain, is substantially more toxic than exposure to BMAA on G14, PND6, 7 and 10 which suggests that BMAA could potentially interfere with neonatal neurogenesis in rats. The observed selective toxicity of BMAA during neurogenesis and, in particular, the observed pattern of neuronal loss observed in BMAA-exposed rats suggest that BMAA elicits its effect by altering dopamine and/or serotonin signaling in rats.
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Affiliation(s)
- Laura Louise Scott
- Department of Biochemistry and Microbiology, Nelson Mandela University, P.O. Box 77 000, Port Elizabeth 6031, South Africa.
| | - Timothy Grant Downing
- Department of Biochemistry and Microbiology, Nelson Mandela University, P.O. Box 77 000, Port Elizabeth 6031, South Africa.
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Scott LL, Downing TG. Β-N-Methylamino-L-Alanine (BMAA) Toxicity Is Gender and Exposure-Age Dependent in Rats. Toxins (Basel) 2017; 10:E16. [PMID: 29280981 PMCID: PMC5793103 DOI: 10.3390/toxins10010016] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 12/21/2017] [Accepted: 12/26/2017] [Indexed: 12/21/2022] Open
Abstract
Cyanobacterial β-N-methylamino-L-alanine (BMAA) has been suggested as a causative or contributory factor in the development of several neurodegenerative diseases. However, no BMAA animal model has adequately shown clinical or behavioral symptoms that correspond to those seen in either Alzheimer's Disease (AD), Amyotrophic Lateral Sclerosis (ALS) or Parkinson's Disease (PD). We present here the first data that show that when neonatal rats were exposed to BMAA on postnatal days 3, 4 and 5, but not on gestational day 14 or postnatally on days 7 or 10, several AD and/or PD-related behavioral, locomotor and cognitive deficits developed. Male rats exhibited severe unilateral hindlimb splay while whole body tremors could be observed in exposed female rats. BMAA-exposed rats failed to identify and discriminate a learned odor, an early non-motor symptom of PD, and exhibited decreased locomotor activity, decreased exploration and increased anxiety in the open field test. Alterations were also observed in the rats' natural passive defense mechanism, and potential memory deficits and changes to the rat's natural height avoidance behavior could be observed as early as PND 30. Spatial learning, short-term working, reference and long-term memory were also impaired in 90-day-old rats that had been exposed to a single dose of BMAA on PND 3-7. These data suggest that BMAA is a developmental neurotoxin, with specific target areas in the brain and spinal cord.
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Affiliation(s)
- Laura Louise Scott
- Department of Biochemistry and Microbiology, Nelson Mandela University, P.O. Box 77 000, Port Elizabeth 6031, South Africa.
| | - Timothy Grant Downing
- Department of Biochemistry and Microbiology, Nelson Mandela University, P.O. Box 77 000, Port Elizabeth 6031, South Africa.
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12
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Cellular and Molecular Aspects of the β-N-Methylamino-l-alanine (BMAA) Mode of Action within the Neurodegenerative Pathway: Facts and Controversy. Toxins (Basel) 2017; 10:toxins10010006. [PMID: 29271898 PMCID: PMC5793093 DOI: 10.3390/toxins10010006] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 12/19/2017] [Accepted: 12/20/2017] [Indexed: 12/12/2022] Open
Abstract
The implication of the cyanotoxin β-N-methylamino-l-alanine (BMAA) in long-lasting neurodegenerative disorders is still a matter of controversy. It has been alleged that chronic ingestion of BMAA through the food chain could be a causative agent of amyotrophic lateral sclerosis (ALS) and several related pathologies including Parkinson syndrome. Both in vitro and in vivo studies of the BMAA mode of action have focused on different molecular targets, demonstrating its toxicity to neuronal cells, especially motoneurons, and linking it to human neurodegenerative diseases. Historically, the hypothesis of BMAA-induced excitotoxicity following the stimulation of glutamate receptors has been established. However, in this paradigm, most studies have shown acute, rather than chronic effects of BMAA. More recently, the interaction of this toxin with neuromelanin, a pigment present in the nervous system, has opened a new research perspective. The issues raised by this toxin are related to its kinetics of action, and its possible incorporation into cellular proteins. It appears that BMAA neurotoxic activity involves different targets through several mechanisms known to favour the development of neurodegenerative processes.
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Tan VX, Mazzocco C, Varney B, Bodet D, Guillemin TA, Bessede A, Guillemin GJ. Detection of the Cyanotoxins L-BMAA Uptake and Accumulation in Primary Neurons and Astrocytes. Neurotox Res 2017; 33:55-61. [PMID: 28852990 DOI: 10.1007/s12640-017-9787-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 07/14/2017] [Accepted: 07/21/2017] [Indexed: 12/12/2022]
Abstract
We show for the first time that a newly developed polyclonal antibody (pAb) can specifically target the cyanotoxin β-methylamino-L-alanine (BMAA) and can be used to enable direct visualization of BMAA entry and accumulation in primary brain cells. We used this pAb to investigate the effect of acute and chronic accumulation, and toxicity of both BMAA and its natural isomer 2,4-diaminobutyric acid (DAB), separately or in combination, on primary cultures of rat neurons. We further present evidence that co-treatment with BMAA and DAB increased neuronal death, as measured by MAP2 fluorescence level, and appeared to reduce BMAA accumulation. DAB is likely to be acting synergistically with BMAA resulting in higher level of cellular toxicity. We also found that glial cells such as microglia and astrocytes are also able to directly uptake BMAA indicating that additional brain cell types are affected by BMAA-induced toxicity. Therefore, BMAA clearly acts at multiple cellular levels to possibly increase the risk of developing neurodegenerative diseases, including neuro- and gliotoxicity and synergetic exacerbation with other cyanotoxins.
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Affiliation(s)
- Vanessa X Tan
- Macquarie University Centre for MND Research, Department of Biological Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | | | - Bianca Varney
- Macquarie University Centre for MND Research, Department of Biological Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | | | - Tristan A Guillemin
- Macquarie University Centre for MND Research, Department of Biological Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | | | - Gilles J Guillemin
- Macquarie University Centre for MND Research, Department of Biological Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, 2109, Australia. .,Neuroinflammation Group, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, 2109, Australia.
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Tan VX, Lassus B, Lim CK, Tixador P, Courte J, Bessede A, Guillemin GJ, Peyrin JM. Neurotoxicity of the Cyanotoxin BMAA Through Axonal Degeneration and Intercellular Spreading. Neurotox Res 2017; 33:62-75. [PMID: 28842862 DOI: 10.1007/s12640-017-9790-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 07/20/2017] [Accepted: 07/21/2017] [Indexed: 12/12/2022]
Abstract
β-Methylamino-L-alanine (BMAA) is implicated in neurodegeneration and neurotoxicity, particularly in ALS-Parkinson Dementia Complex. Neurotoxic properties of BMAA have been partly elucidated, while its transcellular spreading capacity has not been examined. Using reconstructed neuronal networks in microfluidic chips, separating neuronal cells into two subcompartments-(1) the proximal, containing first-order neuronal soma and dendrites, and (2) a distal compartment, containing either only axons originating from first-order neurons or second-order striatal neurons-creates a cortico-striatal network. Using this system, we investigated the toxicity and spreading of BMAA in murine primary neurons. We used a newly developed antibody to detect BMAA in cells. After treatment with 10 μM BMAA, the cyanotoxin was incorporated in first-degree neurons. We also observed a rapid trans-neuronal spread of BMAA to unexposed second-degree neurons in 48 h, followed by axonal degeneration, with limited somatic death. This in vitro study demonstrates BMAA axonal toxicity at sublethal concentrations and, for the first time, the transcellular spreading abilities of BMAA. This neuronal dying forward spread that could possibly be associated with progression of some neurodegenerative diseases especially amyotrophic lateral sclerosis.
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Affiliation(s)
- Vanessa X Tan
- Macquarie University Centre for MND Research, Department of Biological Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia.,Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neuroscience Paris Seine, Adaptation Biologique et vieillissement, F-75005, Paris, France
| | - Benjamin Lassus
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neuroscience Paris Seine, Adaptation Biologique et vieillissement, F-75005, Paris, France
| | - Chai K Lim
- Macquarie University Centre for MND Research, Department of Biological Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Philippe Tixador
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neuroscience Paris Seine, Adaptation Biologique et vieillissement, F-75005, Paris, France
| | - Josquin Courte
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neuroscience Paris Seine, Adaptation Biologique et vieillissement, F-75005, Paris, France
| | | | - Gilles J Guillemin
- Macquarie University Centre for MND Research, Department of Biological Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia.
| | - Jean-Michel Peyrin
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neuroscience Paris Seine, Adaptation Biologique et vieillissement, F-75005, Paris, France.
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15
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Mello FD, Braidy N, Marçal H, Guillemin G, Nabavi SM, Neilan BA. Mechanisms and Effects Posed by Neurotoxic Products of Cyanobacteria/Microbial Eukaryotes/Dinoflagellates in Algae Blooms: a Review. Neurotox Res 2017; 33:153-167. [PMID: 28836116 DOI: 10.1007/s12640-017-9780-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 06/28/2017] [Accepted: 07/05/2017] [Indexed: 12/12/2022]
Abstract
Environmental toxins produced by cyanobacteria and dinoflagellates have increasingly become a public health concern due to their ability to damage several tissues in humans. In particular, emerging evidence has called attention to the neurodegenerative effects of the cyanobacterial toxin β-N-methylamino-L-alanine (BMAA). Furthermore, other toxins such as anatoxin, saxitoxin, microcystin, nodularin and ciguatoxin also have a different range of effects on human tissues, including hepatotoxicity, neurotoxicity and gastrointestinal irritation. However, the vast majority of known environmental toxins have not yet been examined in the context of neurodegenerative disease. This review aims to investigate whether neurotoxic mechanisms can be demonstrated in all aforementioned toxins, and whether there exists a link to neurodegeneration. Management of toxin exposure and potential neuroprotective compounds is also discussed. Collectively, all aforementioned microbial toxins are likely to exert some form of neuronal damage, with many of their modes of action consistent with neurodegeneration. This is important in advancing our current understanding of the cytotoxic potential of environmental toxins upon human brain function, particularly in the context of age-related neurodegenerative disease.
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Affiliation(s)
- Fiona D Mello
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Nady Braidy
- Centre for Healthy Brain Ageing, School of Psychiatry, Faculty of Medicine, The University of New South Wales, Sydney, Australia
| | - Helder Marçal
- Graduate School of Biomedical Engineering, Faculty of Engineering, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Gilles Guillemin
- Neuropharmacology group, MND and Neurodegenerative diseases Research Centre, Macquarie University, Sydney, NSW, Australia
| | - Seyed Mohammad Nabavi
- Applied Biotechnology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Brett A Neilan
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW, 2308, Australia.
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16
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Acute β-N-Methylamino-L-alanine Toxicity in a Mouse Model. J Toxicol 2015; 2015:739746. [PMID: 26604922 PMCID: PMC4641925 DOI: 10.1155/2015/739746] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Revised: 10/06/2015] [Accepted: 10/08/2015] [Indexed: 12/13/2022] Open
Abstract
The cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) is considered to be an “excitotoxin,” and its suggested mechanism of action is killing neurons. Long-term exposure to L-BMAA is believed to lead to neurodegenerative diseases including Parkinson's and Alzheimer's diseases and amyotrophic lateral sclerosis (Lou Gehrig's disease). Objectives of this study were to determine the presumptive median lethal dose (LD50), the Lowest-Observed-Adverse-Effect Level (LOAEL), and histopathologic lesions caused by the naturally occurring BMAA isomer, L-BMAA, in mice. Seventy NIH Swiss Outbred mice (35 male and 35 female) were used. Treatment group mice were injected intraperitoneally with 0.03, 0.3, 1, 2, and 3 mg/g body weight L-BMAA, respectively, and control mice were sham-injected. The presumptive LD50 of L-BMAA was 3 mg/g BW and the LOAEL was 2 mg/g BW. There were no histopathologic lesions in brain, liver, heart, kidney, lung, or spleen in any of the mice during the 14-day study. L-BMAA was detected in brains and livers in all of treated mice but not in control mice. Males injected with 0.03 mg/g BW, 0.3 mg/g BW, and 3.0 mg/g BW L-BMAA showed consistently higher concentrations (P < 0.01) in brain and liver samples as compared to females in those respective groups.
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17
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Cerebral uptake and protein incorporation of cyanobacterial toxin β-N-methylamino-L-alanine. Neuroreport 2014; 24:779-84. [PMID: 23979257 DOI: 10.1097/wnr.0b013e328363fd89] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
β-N-methylamino-L-alanine (BMAA) is a nonprotein amino acid produced by diverse species of free-living cyanobacteria found in terrestrial and aquatic environments worldwide. BMAA has been detected as a soluble (free) and insoluble protein-bound (bound) amino acid in brains of Alzheimer's disease, amyotrophic lateral sclerosis, and Guamanian amyotrophic lateral sclerosis/Parkinsonism dementia complex patients. A toxic reservoir of BMAA in the brain may be excitotoxic to neurons or serve to disrupt cerebral protein homeostasis. Here, we report tracer uptake kinetics and a time course for protein incorporation of [C]-L-BMAA into the brain of C57/BL6 mice. BMAA pharmacokinetic parameters measured in plasma show a rapid distribution phase and a terminal elimination half-life of 1.7 days following bolus intravenous administration. Total [C]-L-BMAA uptake to the brain reached a maximum at 1.5 h. Ex-vivo autoradiography of [C]-labeled BMAA showed dense labeling within the ventricles, choroid plexus, and whole-brain gray matter structures. Radioactivity measured in soluble and trichloroacetic acid precipitates was compared to determine the incorporation of [C]-L-BMAA into total brain protein. The maximal concentration of [C]-L-BMAA was measured in protein-bound fractions of brain at 4 h, followed by a corresponding decrease in the free pool of this nonprotein amino acid. The time-dependent association of [C]-L-BMAA in the protein-bound fraction suggests that BMAA may be trapped in new proteins by protein synthesis-dependent processes. BMAA may accumulate into growing polypeptide chains and recycle to the free pool with protein turnover.
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de Munck E, Muñoz-Sáez E, Miguel BG, Solas MT, Ojeda I, Martínez A, Gil C, Arahuetes RM. β-N-methylamino-l-alanine causes neurological and pathological phenotypes mimicking Amyotrophic Lateral Sclerosis (ALS): the first step towards an experimental model for sporadic ALS. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2013; 36:243-255. [PMID: 23688553 DOI: 10.1016/j.etap.2013.04.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 04/03/2013] [Accepted: 04/10/2013] [Indexed: 05/03/2023]
Abstract
β-N-methylamino-l-alanine (L-BMAA) is a neurotoxic amino acid that has been related to various neurodegenerative diseases. The aim of this work was to analyze the biotoxicity produced by L-BMAA in vivo in rats, trying to elucidate its physiopathological mechanisms and to search for analogies between the found effects and pathologies like Amyotrophic Lateral Sclerosis (ALS). Our data demonstrated that the neurotoxic effects in vivo were dosage-dependent. For evaluating the state of the animals, a neurological evaluation scale was developed as well as a set of functional tests. Ultrastructural cell analysis of spinal motoneurons has revealed alterations both in endoplasmic reticulum and mitochondria. Since GSK3β could play a role in some neuropathological processes, we analyzed the alterations occurring in GSK3β levels in L-BMAA treated rats, we have observed an increase in the active form of GSK3β levels in lumbar spinal cord and motor cerebral cortex. On the other hand, (TAR)-DNA-binding protein 43 (TDP-43) increased in L-BMAA treated animals. Our results indicated that N-acetylaspartate (NAA) declined in animals treated with L-BMAA, and the ratio of N-acetylaspartate/choline (NAA/Cho), N-acetylaspartate/creatine (NAA/Cr) and N-acetylaspartate/choline+creatine (NAA/Cho+Cr) tended to decrease in lumbar spinal cord and motor cortex. This project offers some encouraging results that could help establishing the progress in the development of an animal model of sporadic ALS and L-BMAA could be a useful tool for this purpose.
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Affiliation(s)
- Estefanía de Munck
- Departamento de Biología Animal II, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Emma Muñoz-Sáez
- Departamento de Biología Animal II, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Begoña G Miguel
- Departamento de Bioquímica y Biología Molecular I, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - M Teresa Solas
- Departamento de Biología Celular, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Irene Ojeda
- Departamento de Biología Animal II, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Ana Martínez
- Instituto de Química Médica - Centro Superior de Investigaciones Científicas, 28006 Madrid, Spain
| | - Carmen Gil
- Instituto de Química Médica - Centro Superior de Investigaciones Científicas, 28006 Madrid, Spain
| | - Rosa Mª Arahuetes
- Departamento de Biología Animal II, Universidad Complutense de Madrid, 28040 Madrid, Spain.
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Islam R, Kumimoto EL, Bao H, Zhang B. ALS-linked SOD1 in glial cells enhances ß-N-Methylamino L-Alanine (BMAA)-induced toxicity in Drosophila. F1000Res 2012; 1:47. [PMID: 24627764 PMCID: PMC3945777 DOI: 10.12688/f1000research.1-47.v1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/22/2012] [Indexed: 02/02/2023] Open
Abstract
Environmental factors have been implicated in the etiology of a number of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). However, the role of environmental agents in ALS remains poorly understood. To this end, we used transgenic fruit flies (Drosophila melanogaster) to explore the interaction between mutant superoxide dismutase 1 (SOD1) and chemicals such as ß-N-methylamino L-alanine (BMAA), the herbicide agent paraquat, and superoxide species. We expressed ALS-linked human SOD1 (hSOD1A4V, and hSOD1G85R), hSOD1wt as well as the Drosophila native SOD1 (dSOD1) in motoneurons (MNs) or in glial cells alone and simultaneously in both types of cells. We then examined the effect of BMAA (3 mM), paraquat (20 mM), and hydrogen peroxide (H2O2, 1%) on the lifespan of SOD1-expressing flies. Our data show that glial expression of mutant and wild type hSOD1s reduces the ability of flies to climb. Further, we show that while all three chemicals significantly shorten the lifespan of flies, mutant SOD1 does not have a significant additional effect on the lifespan of flies fed on paraquat, but further shortens the lifespan of flies fed on H2O2. Finally, we show that BMAA shows a dramatic cell-type specific effect with mutant SOD1. Flies with expression of mutant hSOD1 in MNs survived longer on BMAA compared to control flies. In contrast, BMAA significantly shortened the lifespan of flies expressing mutant hSOD1 in glia. Consistent with a neuronal protection role, flies expressing these mutant hSOD1s in both MNs and glia also lived longer. Hence, our studies reveal a synergistic effect of mutant SOD1 with H2O2 and novel roles for mutant hSOD1s in neurons to reduce BMAA toxicity and in glia to enhance the toxicity of BMAA in flies.
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Affiliation(s)
- Rafique Islam
- Department of Biology, University of Oklahoma, Norman, OK, 73019, USA
| | - Emily L Kumimoto
- Department of Biology, University of Oklahoma, Norman, OK, 73019, USA
| | - Hong Bao
- Department of Biology, University of Oklahoma, Norman, OK, 73019, USA
| | - Bing Zhang
- Department of Biology, University of Oklahoma, Norman, OK, 73019, USA
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20
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Chiu AS, Gehringer MM, Braidy N, Guillemin GJ, Welch JH, Neilan BA. Excitotoxic potential of the cyanotoxin β-methyl-amino-l-alanine (BMAA) in primary human neurons. Toxicon 2012; 60:1159-65. [DOI: 10.1016/j.toxicon.2012.07.169] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 07/27/2012] [Accepted: 07/31/2012] [Indexed: 12/27/2022]
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21
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Goto JJ, Koenig JH, Ikeda K. The physiological effect of ingested β-N-methylamino-L-alanine on a glutamatergic synapse in an in vivo preparation. Comp Biochem Physiol C Toxicol Pharmacol 2012; 156:171-7. [PMID: 22841708 DOI: 10.1016/j.cbpc.2012.07.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/09/2012] [Accepted: 07/13/2012] [Indexed: 10/28/2022]
Abstract
The neurotoxin, BMAA (β-N-methylamino-L-alanine), may be a risk factor for amyotrophic lateral sclerosis (ALS), Parkinson's (PD) and Alzheimer's (AD) disease. In vivo experiments have demonstrated that BMAA can cause a number of motor dysfunctions if ingested or injected, and in vitro experiments show that this toxin binds to glutamate receptors with deleterious results. Also, BMAA exists in the human food chain worldwide, and has been detected in the brains of ALS and AD patients. This paper offers the first demonstration by intracellular recording of the effect of ingested BMAA on the postsynaptic response of an identified glutamatergic cell in a living, undissected organism (Drosophila melanogaster), and correlates these observations with the specific motor dysfunctions that result from ingestion. The results suggest that BMAA acts as a glutamate agonist, causing NMDA receptor channels to remain open for prolonged periods of time, thereby damaging the cell by excitotoxicity. The effect on the postsynaptic response became apparent days before the function of the postsynaptic cell (wing beat) became affected. Severely depolarized cells were able to fully recover with the removal of BMAA from the food source, suggesting that blocking BMAA binding in the brain might be a good treatment strategy.
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MESH Headings
- 6-Cyano-7-nitroquinoxaline-2,3-dione/pharmacology
- Amino Acids, Diamino/pharmacology
- Animals
- Behavior, Animal/drug effects
- Behavior, Animal/physiology
- Drosophila melanogaster/drug effects
- Drosophila melanogaster/physiology
- Excitatory Amino Acid Antagonists/pharmacology
- Female
- Motor Neurons/drug effects
- Motor Neurons/physiology
- Muscle Fibers, Skeletal/physiology
- Receptors, AMPA/antagonists & inhibitors
- Receptors, Glutamate/drug effects
- Receptors, Glutamate/physiology
- Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors
- Receptors, N-Methyl-D-Aspartate/physiology
- Synapses/drug effects
- Synapses/physiology
- Synaptic Potentials/drug effects
- Synaptic Potentials/physiology
- Wings, Animal/drug effects
- Wings, Animal/physiology
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Affiliation(s)
- Joy J Goto
- Department of Chemistry, California State University, Fresno, 2555 East San Ramon Ave., MS SB 70, Fresno, CA 93740, USA.
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22
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Chiu AS, Gehringer MM, Welch JH, Neilan BA. Does α-amino-β-methylaminopropionic acid (BMAA) play a role in neurodegeneration? INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2011; 8:3728-46. [PMID: 22016712 PMCID: PMC3194113 DOI: 10.3390/ijerph8093728] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 09/09/2011] [Accepted: 09/09/2011] [Indexed: 12/13/2022]
Abstract
The association of α-amino-β-methylaminopropionic acid (BMAA) with elevated incidence of amyotrophic lateral sclerosis/Parkinson’s disease complex (ALS/PDC) was first identified on the island of Guam. BMAA has been shown to be produced across the cyanobacterial order and its detection has been reported in a variety of aquatic and terrestrial environments worldwide, suggesting that it is ubiquitous. Various in vivo studies on rats, mice, chicks and monkeys have shown that it can cause neurodegenerative symptoms such as ataxia and convulsions. Zebrafish research has also shown disruption to neural development after BMAA exposure. In vitro studies on mice, rats and leeches have shown that BMAA acts predominantly on motor neurons. Observed increases in the generation of reactive oxygen species (ROS) and Ca2+ influx, coupled with disruption to mitochondrial activity and general neuronal death, indicate that the main mode of activity is via excitotoxic mechanisms. The current review pertaining to the neurotoxicity of BMAA clearly demonstrates its ability to adversely affect neural tissues, and implicates it as a potentially significant compound in the aetiology of neurodegenerative disease. When considering the potential adverse health effects upon exposure to this compound, further research to better understand the modes of toxicity of BMAA and the environmental exposure limits is essential.
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Affiliation(s)
- Alexander S Chiu
- The School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia.
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23
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Nagarajan M, Maruthanayagam V, Sundararaman M. A review of pharmacological and toxicological potentials of marine cyanobacterial metabolites. J Appl Toxicol 2011; 32:153-85. [PMID: 21910132 DOI: 10.1002/jat.1717] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Revised: 06/22/2011] [Accepted: 06/22/2011] [Indexed: 11/07/2022]
Abstract
Novel toxic metabolites from marine cyanobacteria have been thoroughly explored. Biologically active and chemically diverse compounds that could be hepatotoxic, neurotoxic or cytotoxic, such as cyclic peptides, lipopeptides, fatty acid amides, alkaloids and saccharides, have been produced from marine cyanobacteria. Many reports have revealed that biosynthesis of active metabolites is predominant during cyanobacterial bloom formation. Marine cyanobacterial toxic metabolites exhibit important biological properties, such as interfering in signal transduction either by activation or blockage of sodium channels or by targeting signaling proteins; inducing apoptosis by disrupting cytoskeletal proteins; and inhibiting membrane transporters, receptors, serine proteases and topoisomerases. The pharmacological importance of these metabolites resides in their proliferation and growth-controlling abilities towards cancer cell lines and disease-causing potent microbial agents (bacteria, virus, fungi and protozoa). Besides their toxic and pharmacological potentials, the present review discusses structural and functional resemblance of marine cyanobacterial metabolites to marine algae, sponges and mollusks.
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Affiliation(s)
- M Nagarajan
- Department of Marine Biotechnology, School of Marine Sciences, Bharathidasan University, Tiruchirappalli-620 024, Tamil Nadu, India
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24
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Early hippocampal cell death, and late learning and memory deficits in rats exposed to the environmental toxin BMAA (β-N-methylamino-L-alanine) during the neonatal period. Behav Brain Res 2011; 219:310-20. [PMID: 21315110 DOI: 10.1016/j.bbr.2011.01.056] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Accepted: 01/29/2011] [Indexed: 11/22/2022]
Abstract
We have reported previously that exposure to the cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) during the neonatal period causes cognitive impairments in adult rats. The aim of this study was to investigate the long-term effects of neonatal BMAA exposure on learning and memory mechanisms and to identify early morphological changes in the neonatal brain. BMAA was injected subcutaneously in rat pups on postnatal days 9-10. BMAA (50 and 200 mg/kg) caused distinct deficits in spatial learning and memory in adult animals but no morphological changes. No impairment of recognition memory was detected, suggesting that neonatal exposure to BMAA preferentially affects neuronal systems that are important for spatial tasks. Histopathological examination revealed early neuronal cell death as determined by TUNEL staining in the hippocampus 24 h after a high dose (600 mg/kg) of BMAA whereas no changes were observed at lower doses (50 and 200 mg/kg). In addition, there was a low degree of neuronal cell death in the retrosplenial and cingulate cortices, areas that are also important for cognitive function. Taken together, these results indicate that BMAA is a developmental neurotoxin inducing long-term changes in cognitive function. The risk posed by BMAA as a potential human neurotoxin merits further consideration, particularly if the proposed biomagnifications in the food chain are confirmed.
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25
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Excitatory amino acid beta-N-methylamino-L-alanine is a putative environmental neurotoxin. JOURNAL OF THE SERBIAN CHEMICAL SOCIETY 2011. [DOI: 10.2298/jsc100629047l] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The amino acid beta-N-methylamino-L-alanine (L-BMAA) has been associated with
the amyotrophic lateral sclerosis/parkinsonismdementia complex in three
distinct western Pacific populations. The putative neurotoxin is produced by
cyanobacteria, which live symbiotically in the roots of cycad trees. L-BMAA
was thought to be a threat only to those few populations whose diet and
medicines rely heavily on cycad seeds. However, the recent discovery that
cyanobacteria from diverse terrestrial, freshwater, and saltwater ecosystems
around the world produce the toxin requires a reassessment of whether it
poses a larger health threat. Therefore, it is proposed that monitoring
L-BMAA levels in cyanobacteria-contaminated water supplies might be prudent.
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26
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β-N-methylamino-L-alanine induces neurological deficits and shortened life span in Drosophila. Toxins (Basel) 2010; 2:2663-79. [PMID: 22069570 PMCID: PMC3153171 DOI: 10.3390/toxins2112663] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 10/28/2010] [Accepted: 11/01/2010] [Indexed: 01/10/2023] Open
Abstract
The neurotoxic non-protein amino acid, β-N-methylamino-L-alanine (BMAA), was first associated with the high incidence of Amyotrophic Lateral Sclerosis/Parkinsonism Dementia Complex (ALS/PDC) in Guam. Recently, BMAA has been implicated as a fierce environmental factor that contributes to the etiology of Alzheimer’s and Parkinson’s diseases, in addition to ALS. However, the toxicity of BMAA in vivo has not been clearly demonstrated. Here we report our investigation of the neurotoxicity of BMAA in Drosophila. We found that dietary intake of BMAA reduced life span, locomotor functions, and learning and memory abilities in flies. The severity of the alterations in phenotype is correlated with the concentration of BMAA detected in flies. Interestingly, developmental exposure to BMAA had limited impact on survival rate, but reduced fertility in females, and caused delayed neurological impairment in aged adults. Our studies indicate that BMAA exposure causes chronic neurotoxicity, and that Drosophila serves as a useful model in dissecting the pathogenesis of ALS/PDC.
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Metabotropic glutamate receptor 1 mediates the electrophysiological and toxic actions of the cycad derivative beta-N-Methylamino-L-alanine on substantia nigra pars compacta DAergic neurons. J Neurosci 2010; 30:5176-88. [PMID: 20392940 DOI: 10.1523/jneurosci.5351-09.2010] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Amyotrophic lateral sclerosis-Parkinson dementia complex (ALS-PDC) is a neurodegenerative disease with ALS, parkinsonism, and Alzheimer's symptoms that is prevalent in the Guam population. beta-N-Methylamino alanine (BMAA) has been proposed as the toxic agent damaging several neuronal types in ALS-PDC, including substantia nigra pars compacta dopaminergic (SNpc DAergic) neurons. BMAA is a mixed glutamate receptor agonist, but the specific pathways activated in DAergic neurons are not yet known. We combined electrophysiology, microfluorometry, and confocal microscopy analysis to monitor membrane potential/current, cytosolic calcium concentration ([Ca(2+)](i)) changes, cytochrome-c (cyt-c) immunoreactivity, and reactive oxygen species (ROS) production induced by BMAA. Rapid toxin applications caused reversible membrane depolarization/inward current and increase of firing rate and [Ca(2+)](i) in DAergic neurons. The inward current (I(BMAA)) was mainly mediated by activation of metabotropic glutamate receptor 1 (mGluR1), coupled to transient receptor potential (TRP) channels, and to a lesser extent, AMPA receptors. Indeed, mGluR1 (CPCCOEt) and TRP channels (SKF 96365; Ruthenium Red) antagonists reduced I(BMAA), and a small component of I(BMAA) was reduced by the AMPA receptor antagonist CNQX. Calcium accumulation was mediated by mGluR1 but not by AMPA receptors. Application of a low concentration of NMDA potentiated the BMAA-mediated calcium increase. Prolonged exposure to BMAA caused significant modifications of membrane properties, calcium overload, cell shrinkage, massive cyt-c release into the cytosol and ROS production. In SNpc GABAergic neurons, BMAA activated only AMPA receptors. Our study identifies the mGluR1-activated mechanism induced by BMAA that may cause the neuronal degeneration and parkinsonian symptoms seen in ALS-PDC. Moreover, environmental exposure to BMAA might possibly also contribute to idiopathic PD.
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28
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Detection of the neurotoxin BMAA within cyanobacteria isolated from freshwater in China. Toxicon 2010; 55:947-53. [DOI: 10.1016/j.toxicon.2009.09.023] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Revised: 07/07/2009] [Accepted: 09/30/2009] [Indexed: 11/24/2022]
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Bradley WG, Mash DC. Beyond Guam: the cyanobacteria/BMAA hypothesis of the cause of ALS and other neurodegenerative diseases. ACTA ACUST UNITED AC 2010; 10 Suppl 2:7-20. [PMID: 19929726 DOI: 10.3109/17482960903286009] [Citation(s) in RCA: 134] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Excitement about neurogenetics in the last two decades has diverted attention from environmental causes of sporadic ALS. Fifty years ago endemic foci of ALS with a frequency one hundred times that in the rest of the world attracted attention since they offered the possibility of finding the cause for non-endemic ALS throughout the world. Research on Guam suggested that ALS, Parkinson's disease and dementia (the ALS/PDC complex) was due to a neurotoxic non-protein amino acid, beta-methylamino-L-alanine (BMAA), in the seeds of the cycad Cycas micronesica. Recent discoveries that found that BMAA is produced by symbiotic cyanobacteria within specialized roots of the cycads; that the concentration of protein-bound BMAA is up to a hundred-fold greater than free BMAA in the seeds and flour; that various animals forage on the seeds (flying foxes, pigs, deer), leading to biomagnification up the food chain in Guam; and that protein-bound BMAA occurs in the brains of Guamanians dying of ALS/PDC (average concentration 627 microg/g, 5 mM) but not in control brains have rekindled interest in BMAA as a possible trigger for Guamanian ALS/PDC. Perhaps most intriguing is the finding that BMAA is present in brain tissues of North American patients who had died of Alzheimer's disease (average concentration 95 microg/g, 0.8mM); this suggests a possible etiological role for BMAA in non-Guamanian neurodegenerative diseases. Cyanobacteria are ubiquitous throughout the world, so it is possible that all humans are exposed to low amounts of cyanobacterial BMAA, that protein-bound BMAA in human brains is a reservoir for chronic neurotoxicity, and that cyanobacterial BMAA is a major cause of progressive neurodegenerative diseases including ALS worldwide. Though Montine et al., using different HPLC method and assay techniques from those used by Cox and colleagues, were unable to reproduce the findings of Murch et al., Mash and colleagues using the original techniques of Murch et al. have recently confirmed the presence of protein-bound BMAA in the brains of North American patients dying with ALS and Alzheimer's disease (concentrations >100 microg/g) but not in the brains of non-neurological controls or Huntington's disease. We hypothesize that individuals who develop neurodegenerations may have a genetic susceptibility because of inability to prevent BMAA accumulation in brain proteins and that the particular pattern of neurodegeneration that develops depends on the polygenic background of the individual.
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Affiliation(s)
- Walter G Bradley
- Department of Neurology, Miller School of Medicine, University of Miami, 1120 NW 14 Street, Miami, FL 33136, USA.
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Stewart I. Environmental risk factors for temporal lobe epilepsy – Is prenatal exposure to the marine algal neurotoxin domoic acid a potentially preventable cause? Med Hypotheses 2010; 74:466-81. [DOI: 10.1016/j.mehy.2009.10.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Accepted: 10/04/2009] [Indexed: 01/29/2023]
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Krüger T, Mönch B, Oppenhäuser S, Luckas B. LC–MS/MS determination of the isomeric neurotoxins BMAA (β-N-methylamino-l-alanine) and DAB (2,4-diaminobutyric acid) in cyanobacteria and seeds of Cycas revoluta and Lathyrus latifolius. Toxicon 2010; 55:547-57. [DOI: 10.1016/j.toxicon.2009.10.009] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Revised: 09/24/2009] [Accepted: 10/02/2009] [Indexed: 10/20/2022]
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Caller TA, Doolin JW, Haney JF, Murby AJ, West KG, Farrar HE, Ball A, Harris BT, Stommel EW. A cluster of amyotrophic lateral sclerosis in New Hampshire: A possible role for toxic cyanobacteria blooms. ACTA ACUST UNITED AC 2009; 10 Suppl 2:101-8. [DOI: 10.3109/17482960903278485] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Karlsson O, Roman E, Brittebo EB. Long-term Cognitive Impairments in Adult Rats Treated Neonatally with β-N-Methylamino-L-Alanine. Toxicol Sci 2009; 112:185-95. [DOI: 10.1093/toxsci/kfp196] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Santucci S, Zsürger N, Chabry J. β-N-methylamino-l-alanine inducedin vivoretinal cell death. J Neurochem 2009; 109:819-25. [DOI: 10.1111/j.1471-4159.2009.06022.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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1H NMR determination of β-N-methylamino-l-alanine (l-BMAA) in environmental and biological samples. Toxicon 2009; 53:578-83. [DOI: 10.1016/j.toxicon.2008.12.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2008] [Revised: 12/08/2008] [Accepted: 12/09/2008] [Indexed: 11/23/2022]
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Lopicic S, Nedeljkov V, Cemerikic D. Augmentation and ionic mechanism of effect of beta-N-methylamino-L-alanine in presence of bicarbonate on membrane potential of Retzius nerve cells of the leech Haemopis sanguisuga. Comp Biochem Physiol A Mol Integr Physiol 2009; 153:284-92. [PMID: 19272457 DOI: 10.1016/j.cbpa.2009.02.038] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Revised: 02/23/2009] [Accepted: 02/24/2009] [Indexed: 11/19/2022]
Abstract
The role of neurotoxic non-protein amino acid beta-N-methylamino-L-alanine (L-BMAA) as a putative causative agent of Western pacific amyotrophic lateral sclerosis/Parkinsonism dementia complex (ALS/PDC) has recently been reinvigorated. In view of this data we have investigated the strength and mechanism of effect of L-BMAA in presence of 20 mmol/L bicarbonate (a cofactor for BMAA) on membrane potential of the Leech Haemopis sanguisuga. Our results show that L-BMAA has excitatory effect in bicarbonate containing solution, which is more potent than in nominally bicarbonate free solution. This potentiation by bicarbonate is L-BMAA specific, as it was not exhibited by beta-N-oxalylamino-L-alanine. The effect of L-BMAA was partially blocked by non-NMDA receptor antagonist CNQX. Application of L-BMAA caused a decrease in input membrane resistance, an increase of intracellular sodium activity, and a decrease of intracellular potassium activity. Present findings indicate that BMAA could initiate excitotoxicity through activation of non-NMDA ionotropic glutamate receptors.
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Affiliation(s)
- Srdjan Lopicic
- Institute for Pathological Physiology, Medical faculty Belgrade, Belgrade, Serbia.
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Tabata RC, Wilson JMB, Ly P, Zwiegers P, Kwok D, Van Kampen JM, Cashman N, Shaw CA. Chronic exposure to dietary sterol glucosides is neurotoxic to motor neurons and induces an ALS-PDC phenotype. Neuromolecular Med 2008; 10:24-39. [PMID: 18196479 PMCID: PMC2814814 DOI: 10.1007/s12017-007-8020-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2007] [Accepted: 11/02/2007] [Indexed: 12/26/2022]
Abstract
Epidemiological studies of the Guamanian variants of amyotrophic lateral sclerosis (ALS) and parkinsonism, amyotrophic lateral sclerosis-parkinsonism dementia complex (ALS-PDC), have shown a positive correlation between consumption of washed cycad seed flour and disease occurrence. Previous in vivo studies by our group have shown that the same seed flour induces ALS and PDC phenotypes in out bred adult male mice. In vitro studies using isolated cycad compounds have also demonstrated that several of these are neurotoxic, specifically, a number of water insoluble phytosterol glucosides of which beta-sitosterol beta-D: -glucoside (BSSG) forms the largest fraction. BSSG is neurotoxic to motor neurons and other neuronal populations in culture. The present study shows that an in vitro hybrid motor neuron (NSC-34) culture treated with BSSG undergoes a dose-dependent cell loss. Surviving cells show increased expression of HSP70, decreased cytosolic heavy neurofilament expression, and have various morphological abnormalities. CD-1 mice fed mouse chow pellets containing BSSG for 15 weeks showed motor deficits and motor neuron loss in the lumbar and thoracic spinal cord, along with decreased glutamate transporter labelling, and increased glial fibrillary acid protein reactivity. Other pathological outcomes included increased caspase-3 labelling in the striatum and decreased tyrosine-hydroxylase labelling in the striatum and substantia nigra. C57BL/6 mice fed BSSG-treated pellets for 10 weeks exhibited progressive loss of motor neurons in the lumbar spinal cord that continued to worsen even after the BSSG exposure ended. These results provide further support implicating sterol glucosides as one potential causal factor in the motor neuron pathology previously associated with cycad consumption and ALS-PDC.
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Affiliation(s)
- R C Tabata
- Department of Experimental Medicine, University of British Columbia, Rm 386, 828 W.10th Ave, Vancouver, BC, Canada, V5Z1L8
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Karamyan VT, Speth RC. Animal models of BMAA neurotoxicity: a critical review. Life Sci 2007; 82:233-46. [PMID: 18191417 DOI: 10.1016/j.lfs.2007.11.020] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Revised: 11/20/2007] [Accepted: 11/26/2007] [Indexed: 01/26/2023]
Abstract
Of all the molecules reported to have toxicological effects, BMAA (beta-methylamino alanine) stands out as having the most checkered past. In the late 1960's it was reported to be a toxic component of the cycad flour consumed by Chamorros on Guam which caused the high incidence of amyotrophic lateral sclerosis (ALS) in Guam, that was associated with a Parkinson's disease-like dementia complex (ALS-PDC). However, because ALS-PDC is a slow onset disease, manifesting itself as long as 30 years following exposure to the putative neurotoxin, and only acute toxic effects of BMAA were observed in animal studies, interest in BMAA waned. A seminal study by Spencer et al., in 1987 showing neurological impairments with long-term BMAA-fed monkeys revived the hypothesis that BMAA could cause ALS-PDC. However, the amounts of BMAA used in that study were viewed as being the equivalent of a person consuming their body weight of cycad flour every day. Again, the BMAA hypothesis was discarded. Recently a third iteration of the BMAA hypothesis has been proposed. It is based on the discovery of a novel dietary source of BMAA via biomagnification of BMAA in flying foxes, once consumed in great amounts by Chamorros. Also, reports that BMAA can be incorporated into plant and animal proteins, a heretofore unrecognized dietary source of BMAA, further solidified this new hypothesis. However, once again this hypothesis has its detractors and it remains controversial. This manuscript critically evaluates in vivo studies directed at establishing an animal model of BMAA-induced ALS-PDC and their implications for this hypothesis.
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Affiliation(s)
- Vardan T Karamyan
- Department of Pharmacology, School of Pharmacy, University of Mississippi, MS 38677, USA
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