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McMillen S, Lönnerdal B. Postnatal Iron Supplementation with Ferrous Sulfate vs. Ferrous Bis-Glycinate Chelate: Effects on Iron Metabolism, Growth, and Central Nervous System Development in Sprague Dawley Rat Pups. Nutrients 2021; 13:1406. [PMID: 33921980 PMCID: PMC8143548 DOI: 10.3390/nu13051406] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/18/2021] [Accepted: 04/20/2021] [Indexed: 02/05/2023] Open
Abstract
Iron-fortified formulas and iron drops (both usually ferrous sulfate, FS) prevent early life iron deficiency, but may delay growth and adversely affect neurodevelopment by providing excess iron. We used a rat pup model to investigate iron status, growth, and development outcomes following daily iron supplementation (10 mg iron/kg body weight, representative of iron-fortified formula levels) with FS or an alternative, bioavailable form of iron, ferrous bis-glycinate chelate (FC). On postnatal day (PD) 2, sex-matched rat litters (n = 3 litters, 10 pups each) were randomly assigned to receive FS, FC, or vehicle control until PD 14. On PD 15, we evaluated systemic iron regulation and CNS mineral interactions and we interrogated iron loading outcomes in the hippocampus, in search of mechanisms by which iron may influence neurodevelopment. Body iron stores were elevated substantially in iron-supplemented pups. All pups gained weight normally, but brain size on PD 15 was dependent on iron source. This may have been associated with reduced hippocampal oxidative stress but was not associated with CNS mineral interactions, iron regulation, or myelination, as these were unchanged with iron supplementation. Additional studies are warranted to investigate iron form effects on neurodevelopment so that iron recommendations can be optimized for all infants.
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Affiliation(s)
| | - Bo Lönnerdal
- Department of Nutrition, University of California, Davis, CA 95616, USA;
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Billings JL, Gordon SL, Rawling T, Doble PA, Bush AI, Adlard PA, Finkelstein DI, Hare DJ. l
‐3,4‐dihydroxyphenylalanine (
l
‐DOPA) modulates brain iron, dopaminergic neurodegeneration and motor dysfunction in iron overload and mutant alpha‐synuclein mouse models of Parkinson's disease. J Neurochem 2019; 150:88-106. [DOI: 10.1111/jnc.14676] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 12/15/2018] [Accepted: 01/16/2019] [Indexed: 02/06/2023]
Affiliation(s)
- Jessica L. Billings
- Melbourne Dementia Research Centre at The Florey Institute of Neuroscience and Mental Health and The University of Melbourne Parkville Victoria Australia
| | - Sarah L. Gordon
- Melbourne Dementia Research Centre at The Florey Institute of Neuroscience and Mental Health and The University of Melbourne Parkville Victoria Australia
| | - Tristan Rawling
- School of Mathematical and Physical Sciences Faculty of Science University of Technology Sydney Broadway New South Wales Australia
| | - Philip A. Doble
- Elemental Bio‐imaging Facility University of Technology Sydney Broadway New South Wales Australia
| | - Ashley I. Bush
- Melbourne Dementia Research Centre at The Florey Institute of Neuroscience and Mental Health and The University of Melbourne Parkville Victoria Australia
| | - Paul A. Adlard
- Melbourne Dementia Research Centre at The Florey Institute of Neuroscience and Mental Health and The University of Melbourne Parkville Victoria Australia
| | - David I. Finkelstein
- Melbourne Dementia Research Centre at The Florey Institute of Neuroscience and Mental Health and The University of Melbourne Parkville Victoria Australia
| | - Dominic J. Hare
- Melbourne Dementia Research Centre at The Florey Institute of Neuroscience and Mental Health and The University of Melbourne Parkville Victoria Australia
- Elemental Bio‐imaging Facility University of Technology Sydney Broadway New South Wales Australia
- Department of Clinical Pathology The University of Melbourne Parkville Victoria Australia
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Agrawal S, Berggren KL, Marks E, Fox JH. Impact of high iron intake on cognition and neurodegeneration in humans and in animal models: a systematic review. Nutr Rev 2017; 75:456-470. [PMID: 28505363 PMCID: PMC5914328 DOI: 10.1093/nutrit/nux015] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Context Accumulation of brain iron is linked to aging and protein-misfolding neurodegenerative diseases. High iron intake may influence important brain health outcomes in later life. Objective The aim of this systematic review was to examine evidence from animal and human studies of the effects of high iron intake or peripheral iron status on adult cognition, brain aging, and neurodegeneration. Data Sources MEDLINE, Scopus, CAB Abstracts, the Cochrane Central Register of Clinical Trials, and OpenGrey databases were searched. Study Selection Studies investigating the effect of elevated iron intake at all postnatal life stages in mammalian models and humans on measures of adult brain health were included. Data Extraction Data were extracted and evaluated by two authors independently, with discrepancies resolved by discussion. Neurodegenerative disease diagnosis and/or behavioral/cognitive, biochemical, and brain morphologic findings were used to study the effects of iron intake or peripheral iron status on brain health. Risk of bias was assessed for animal and human studies. PRISMA guidelines for reporting systematic reviews were followed. Results Thirty-four preclinical and 14 clinical studies were identified from database searches. Thirty-three preclinical studies provided evidence supporting an adverse effect of nutritionally relevant high iron intake in neonates on brain-health-related outcomes in adults. Human studies varied considerably in design, quality, and findings; none investigated the effects of high iron intake in neonates/infants. Conclusions Human studies are needed to verify whether dietary iron intake levels used in neonates/infants to prevent iron deficiency have effects on brain aging and neurodegenerative disease outcomes.
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Affiliation(s)
- Sonal Agrawal
- S. Agrawal and J.H. Fox are with the Department of Veterinary Sciences, University of Wyoming, Laramie, Wyoming, USA. K.L. Berggren is with the Department of Radiation Oncology, University of New Mexico Cancer Center, Albuquerque, New Mexico, USA. E. Marks is with the Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Kiersten L. Berggren
- S. Agrawal and J.H. Fox are with the Department of Veterinary Sciences, University of Wyoming, Laramie, Wyoming, USA. K.L. Berggren is with the Department of Radiation Oncology, University of New Mexico Cancer Center, Albuquerque, New Mexico, USA. E. Marks is with the Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Eileen Marks
- S. Agrawal and J.H. Fox are with the Department of Veterinary Sciences, University of Wyoming, Laramie, Wyoming, USA. K.L. Berggren is with the Department of Radiation Oncology, University of New Mexico Cancer Center, Albuquerque, New Mexico, USA. E. Marks is with the Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Jonathan H. Fox
- S. Agrawal and J.H. Fox are with the Department of Veterinary Sciences, University of Wyoming, Laramie, Wyoming, USA. K.L. Berggren is with the Department of Radiation Oncology, University of New Mexico Cancer Center, Albuquerque, New Mexico, USA. E. Marks is with the Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
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Billings JL, Hare DJ, Nurjono M, Volitakis I, Cherny RA, Bush AI, Adlard PA, Finkelstein DI. Effects of Neonatal Iron Feeding and Chronic Clioquinol Administration on the Parkinsonian Human A53T Transgenic Mouse. ACS Chem Neurosci 2016; 7:360-6. [PMID: 26712118 DOI: 10.1021/acschemneuro.5b00305] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Increased nigral iron (Fe) is a cardinal feature of Parkinson's disease, as is the accumulation of aggregates comprising α-synuclein. We used wild-type mice and transgenic mice overexpressing the human A53T mutation to α-synuclein to examine the influence of increased Fe (days 10-17 postpartum) on the parkinsonian development phenotype of these animals (including abnormal nigral Fe levels and deficits in both cell numbers and locomotor activity), and to explore the impact of the Fe chelator clioquinol in the model. Both untreated and Fe-loaded A53T mice showed similar levels of nigral cell loss, though 5 months of clioquinol treatment was only able to prevent the loss in the non-Fe-loaded A53T group. Iron levels in the Fe-loaded A53T mice returned to normal at 8 months, though effects of dopamine denervation remained, demonstrated by limited locomotor activity and sustained neuron loss. These data suggest that Fe exposure during a critical developmental window, combined with the overexpression mutant α-synuclein, presents a disease phenotype resistant to intervention using clioquinol later in life.
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Affiliation(s)
- Jessica L. Billings
- The
Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Dominic J. Hare
- The
Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3052, Australia
- Elemental
Bio-imaging Facility, University of Technology Sydney, Broadway, New South Wales 2007, Australia
| | - Milawaty Nurjono
- The
Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Irene Volitakis
- The
Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Robert A. Cherny
- The
Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Ashley I. Bush
- The
Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3052, Australia
| | - Paul A. Adlard
- The
Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3052, Australia
| | - David I. Finkelstein
- The
Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3052, Australia
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5
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Berggren KL, Chen J, Fox J, Miller J, Dodds L, Dugas B, Vargas L, Lothian A, McAllum E, Volitakis I, Roberts B, Bush AI, Fox JH. Neonatal iron supplementation potentiates oxidative stress, energetic dysfunction and neurodegeneration in the R6/2 mouse model of Huntington's disease. Redox Biol 2015; 4:363-74. [PMID: 25703232 PMCID: PMC4348428 DOI: 10.1016/j.redox.2015.02.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 02/04/2015] [Accepted: 02/05/2015] [Indexed: 02/08/2023] Open
Abstract
Huntington's disease (HD) is a progressive neurodegenerative disorder caused by a CAG repeat expansion that encodes a polyglutamine tract in huntingtin (htt) protein. Dysregulation of brain iron homeostasis, oxidative stress and neurodegeneration are consistent features of the HD phenotype. Therefore, environmental factors that exacerbate oxidative stress and iron dysregulation may potentiate HD. Iron supplementation in the human population is common during infant and adult-life stages. In this study, iron supplementation in neonatal HD mice resulted in deterioration of spontaneous motor running activity, elevated levels of brain lactate and oxidized glutathione consistent with increased energetic dysfunction and oxidative stress, and increased striatal and motor cortical neuronal atrophy, collectively demonstrating potentiation of the disease phenotype. Oxidative stress, energetic, and anatomic markers of degeneration were not affected in wild-type littermate iron-supplemented mice. Further, there was no effect of elevated iron intake on disease outcomes in adult HD mice. We have demonstrated an interaction between the mutant huntingtin gene and iron supplementation in neonatal HD mice. Findings indicate that elevated neonatal iron intake potentiates mouse HD and promotes oxidative stress and energetic dysfunction in brain. Neonatal-infant dietary iron intake level may be an environmental modifier of human HD.
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Affiliation(s)
- Kiersten L Berggren
- Department of Veterinary Sciences, University of Wyoming, 1174 Snowy Range Road, Laramie, WY 82070, USA.
| | - Jianfang Chen
- Department of Veterinary Sciences, University of Wyoming, 1174 Snowy Range Road, Laramie, WY 82070, USA; Neuroscience Graduate Program, University of Wyoming, 1174 Snowy Range Road, Laramie, WY 82070, USA.
| | - Julia Fox
- Department of Veterinary Sciences, University of Wyoming, 1174 Snowy Range Road, Laramie, WY 82070, USA.
| | - Jonathan Miller
- Department of Veterinary Sciences, University of Wyoming, 1174 Snowy Range Road, Laramie, WY 82070, USA.
| | - Lindsay Dodds
- Department of Veterinary Sciences, University of Wyoming, 1174 Snowy Range Road, Laramie, WY 82070, USA.
| | - Bryan Dugas
- Department of Veterinary Sciences, University of Wyoming, 1174 Snowy Range Road, Laramie, WY 82070, USA.
| | - Liset Vargas
- Department of Veterinary Sciences, University of Wyoming, 1174 Snowy Range Road, Laramie, WY 82070, USA.
| | - Amber Lothian
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Erin McAllum
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Irene Volitakis
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria 3010, Australia.
| | - Blaine Roberts
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria 3010, Australia.
| | - Ashley I Bush
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria 3010, Australia.
| | - Jonathan H Fox
- Department of Veterinary Sciences, University of Wyoming, 1174 Snowy Range Road, Laramie, WY 82070, USA; Neuroscience Graduate Program, University of Wyoming, 1174 Snowy Range Road, Laramie, WY 82070, USA.
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Noradrenergic-Dopaminergic Interactions Due to DSP-4-MPTP Neurotoxin Treatments: Iron Connection. Curr Top Behav Neurosci 2015; 29:73-86. [PMID: 26718588 DOI: 10.1007/7854_2015_411] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The investigations of noradrenergic lesions and dopaminergic lesions have established particular profiles of functional deficits and accompanying alterations of biomarkers in brain regions and circuits. In the present account, the focus of these lesions is directed toward the effects upon dopaminergic neurotransmission and expression that are associated with the movement disorders and psychosis-like behavior. In this context, it was established that noradrenergic denervation, through administration of the selective noradrenaline (NA) neurotoxin, DSP-4, should be performed prior to the depletion of dopamine (DA) with the selective neurotoxin, MPTP. Employing this regime, it was shown that (i) following DSP-4 (50 mg/kg) pretreatment of C57/Bl6 mice, both the functional and neurochemical (DA loss) effects of MPTP (2 × 20 and 2 × 40 mg/kg) were markedly exacerbated, and (ii) following postnatal iron (Fe(2+), 7.5 mg/kg, on postnatal days 19-12), pretreatment with DSP-4 followed by the lower 2 × 20 mg/kg MPTP dose induced even greater losses of motor behavior and striatal DA. As yet, the combination of NA-DA depletions, and even more so Fe(2+)-NA-DA depletion, has been considered to present a movement disorder aspect although studies exploring cognitive domains are lacking. With intrusion of iron overload into this formula, the likelihood of neuropsychiatric disorder, as well, unfolds.
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7
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Rhodes SL, Buchanan DD, Ahmed I, Taylor KD, Loriot MA, Sinsheimer JS, Bronstein JM, Elbaz A, Mellick GD, Rotter JI, Ritz B. Pooled analysis of iron-related genes in Parkinson's disease: association with transferrin. Neurobiol Dis 2013; 62:172-8. [PMID: 24121126 DOI: 10.1016/j.nbd.2013.09.019] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 08/31/2013] [Accepted: 09/27/2013] [Indexed: 01/04/2023] Open
Abstract
Pathologic features of Parkinson's disease (PD) include death of dopaminergic neurons in the substantia nigra, presence of α-synuclein containing Lewy bodies, and iron accumulation in PD-related brain regions. The observed iron accumulation may be contributing to PD etiology but it also may be a byproduct of cell death or cellular dysfunction. To elucidate the possible role of iron accumulation in PD, we investigated genetic variation in 16 genes related to iron homeostasis in three case-control studies from the United States, Australia, and France. After screening 90 haplotype tagging single nucleotide polymorphisms (SNPs) within the genes of interest in the US study population, we investigated the five most promising gene regions in two additional independent case-control studies. For the pooled data set (1289 cases, 1391 controls) we observed a protective association (OR=0.83, 95% CI: 0.71-0.96) between PD and a haplotype composed of the A allele at rs1880669 and the T allele at rs1049296 in transferrin (TF; GeneID: 7018). Additionally, we observed a suggestive protective association (OR=0.87, 95% CI: 0.74-1.02) between PD and a haplotype composed of the G allele at rs10247962 and the A allele at rs4434553 in transferrin receptor 2 (TFR2; GeneID: 7036). We observed no associations in our pooled sample for haplotypes in SLC40A1, CYB561, or HFE. Taken together with previous findings in model systems, our results suggest that TF or a TF-TFR2 complex may have a role in the etiology of PD, possibly through iron misregulation or mitochondrial dysfunction within dopaminergic neurons.
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Affiliation(s)
- Shannon L Rhodes
- Department of Epidemiology, UCLA Fielding School of Public Health, 650 Charles E. Young Drive S, Los Angeles, CA 90095-1772, USA.
| | - Daniel D Buchanan
- Cancer and Population Studies Group, Queensland Institute of Medical Research, 300 Herston Rd, Brisbane, QLD 4006, Australia; University of Queensland, School of Medicine, Brisbane, Australia; Princess Alexandra Hospital, Australia
| | - Ismaïl Ahmed
- Centre for Research in Epidemiology and Population Health, Biostatistics team, INSERM U1018, F-94276 le Kremlin Bicêtre, France; Univ Paris-Sud, UMRS 1018, F-94276 le Kremlin Bicêtre, France
| | - Kent D Taylor
- Institute for Translational Genomics and Population Sciences, Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, 1124 West Carson, Bldg E5, Torrance, CA 90502, USA
| | - Marie-Anne Loriot
- Sorbonne Paris Cité, Université Paris Descartes, INSERM UMR-S 775, France; Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service de Biochimie, Unité Fonctionnelle de Pharmacogénétique et Oncologie Moléculaire, France
| | - Janet S Sinsheimer
- Department of Human Genetics, David Geffen School of Medicine at UCLA, 695 Charles E. Young Drive South, Box 708822, Los Angeles, CA 90095-7088, USA; Department of Biomathematics, David Geffen School of Medicine at UCLA, Box 951766, Room 5303 Life Sciences, Los Angeles, CA 90095-1766, USA; Department of Biostatistics, UCLA Fielding School of Public Health, 650 Charles E. Young Drive S, Los Angeles, CA 90095-1772, USA
| | - Jeff M Bronstein
- Department of Neurology, David Geffen School of Medicine at UCLA, 710 Westwood Plaza, Los Angeles, CA 90095-1769, USA
| | - Alexis Elbaz
- Centre for Research in Epidemiology and Population Health, Social and Occupational Determinants of Health, INSERM U1018, F-94807 Villejuif, France; Univ Versailles St-Quentin, UMRS 1018, F-94807, Villejuif France
| | - George D Mellick
- Eskitis Institute for Drug Discovery, Griffith University, Nathan 4111, Brisbane, Australia; Department of Neurology, Princess Alexandra Hospital, Brisbane, Australia
| | - Jerome I Rotter
- Institute for Translational Genomics and Population Sciences, Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, 1124 West Carson, Bldg E5, Torrance, CA 90502, USA
| | - Beate Ritz
- Department of Epidemiology, UCLA Fielding School of Public Health, 650 Charles E. Young Drive S, Los Angeles, CA 90095-1772, USA; Department of Neurology, David Geffen School of Medicine at UCLA, 710 Westwood Plaza, Los Angeles, CA 90095-1769, USA; Department of Environmental Health Sciences, UCLA Fielding School of Public Health, 650 Charles E. Young Drive S, Los Angeles, CA 90095-1772, USA
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Sant'Anna MCB, Soares VDM, Seibt KJ, Ghisleni G, Rico EP, Rosemberg DB, de Oliveira JR, Schröder N, Bonan CD, Bogo MR. Iron exposure modifies acetylcholinesterase activity in zebrafish (Danio rerio) tissues: distinct susceptibility of tissues to iron overload. FISH PHYSIOLOGY AND BIOCHEMISTRY 2011; 37:573-581. [PMID: 21194010 DOI: 10.1007/s10695-010-9459-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Accepted: 12/06/2010] [Indexed: 05/30/2023]
Abstract
Iron is one the most abundant metals on the earth being essential for living organisms even though its free form can be toxic. The overload of this metal may be related with some disorders, like Alzheimer and Parkinson diseases, and hemochromatosis in the liver. The aim of the present study was to evaluate the effects of iron on acetylcholinesterase (AChE) activity in brain and liver of zebrafish and to investigate the possible correlation with the iron content in these tissues. Different corresponding concentrations of iron were tested using in vitro (0.018, 0.268, and 2.6 mM) and in vivo (1, 15, and 150 mg/l) assays. The in vitro studies showed that iron promoted a significant increase in AChE activity in brain (52%) and liver (53%) at the higher concentration (2.6 mM). In the in vivo assays, a significant increase in this enzyme activity was observed in the presence of 15 mg/l in both, brain (62%) and liver tissue (70%). Semiquantitative RT-PCR did not reveal significant changes in acetylthiocholinesterase mRNA levels. Moreover, we observed that iron content was significantly increased in liver tissue when exposed to 15 (226%) and 150 mg/l (200%). These results indicate that iron can promote significant alterations in AChE activity which probably is not directly related to the iron content in zebrafish tissues.
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Affiliation(s)
- M C B Sant'Anna
- Laboratório de Biologia Genômica e Molecular, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Avenida Ipiranga 6681, 90619-900 Porto Alegre, RS, Brazil
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Castiglioni E, Finazzi D, Goldwurm S, Pezzoli G, Forni G, Girelli D, Maccarinelli F, Poli M, Ferrari M, Cremonesi L, Arosio P. Analysis of nucleotide variations in genes of iron management in patients of Parkinson's disease and other movement disorders. PARKINSONS DISEASE 2010; 2011:827693. [PMID: 20981230 PMCID: PMC2957853 DOI: 10.4061/2011/827693] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Accepted: 09/27/2010] [Indexed: 12/30/2022]
Abstract
The capacity to act as an electron donor and acceptor makes iron an essential cofactor of many vital processes. Its balance in the body has to be tightly regulated since its excess can be harmful by favouring oxidative damage, while its deficiency can impair fundamental activities like erythropoiesis. In the brain, an accumulation of iron or an increase in its availability has been associated with the development and/or progression of different degenerative processes, including Parkinson's disease, while iron paucity seems to be associated with cognitive deficits, motor dysfunction, and restless legs syndrome. In the search of DNA sequence variations affecting the individual predisposition to develop movement disorders, we scanned by DHPLC the exons and intronic boundary regions of ceruloplasmin, iron regulatory protein 2, hemopexin, hepcidin and hemojuvelin genes in cohorts of subjects affected by Parkinson's disease and idiopathic neurodegeneration with brain iron accumulation (NBIA). Both novel and known sequence variations were identified in most of the genes, but none of them seemed to be significantly associated to the movement diseases of interest.
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Affiliation(s)
- Emanuela Castiglioni
- Genomic Unit for the Diagnosis of Human Pathologies, Center for Genomics, Bioinformatics and Biostatistics, San Raffaele Scientific Institute, 20132 Milan, Italy
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10
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Running wheel activity restores MPTP-induced functional deficits. J Neural Transm (Vienna) 2010; 118:407-20. [DOI: 10.1007/s00702-010-0474-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2010] [Accepted: 08/23/2010] [Indexed: 01/07/2023]
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George JL, Mok S, Moses D, Wilkins S, Bush AI, Cherny RA, Finkelstein DI. Targeting the progression of Parkinson's disease. Curr Neuropharmacol 2010; 7:9-36. [PMID: 19721815 PMCID: PMC2724666 DOI: 10.2174/157015909787602814] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 08/15/2008] [Accepted: 09/09/2008] [Indexed: 02/07/2023] Open
Abstract
By the time a patient first presents with symptoms of Parkinson's disease at the clinic, a significant proportion (50-70%) of the cells in the substantia nigra (SN) has already been destroyed. This degeneration progresses until, within a few years, most of the cells have died. Except for rare cases of familial PD, the initial trigger for cell loss is unknown. However, we do have some clues as to why the damage, once initiated, progresses unabated. It would represent a major advance in therapy to arrest cell loss at the stage when the patient first presents at the clinic. Current therapies for Parkinson's disease focus on relieving the motor symptoms of the disease, these unfortunately lose their effectiveness as the neurodegeneration and symptoms progress. Many experimental approaches are currently being investigated attempting to alter the progression of the disease. These range from replacement of the lost neurons to neuroprotective therapies; each of these will be briefly discussed in this review. The main thrust of this review is to explore the interactions between dopamine, alpha synuclein and redox-active metals. There is abundant evidence suggesting that destruction of SN cells occurs as a result of a self-propagating series of reactions involving dopamine, alpha synuclein and redox-active metals. A potent reducing agent, the neurotransmitter dopamine has a central role in this scheme, acting through redox metallo-chemistry to catalyze the formation of toxic oligomers of alpha-synuclein and neurotoxic metabolites including 6-hydroxydopamine. It has been hypothesized that these feed the cycle of neurodegeneration by generating further oxidative stress. The goal of dissecting and understanding the observed pathological changes is to identify therapeutic targets to mitigate the progression of this debilitating disease.
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Affiliation(s)
- J L George
- The Mental Health Research Institute of Victoria , 155 Oak Street, Parkville, Victoria 3052, Australia
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Archer T. Effects of exogenous agents on brain development: stress, abuse and therapeutic compounds. CNS Neurosci Ther 2010; 17:470-89. [PMID: 20553311 DOI: 10.1111/j.1755-5949.2010.00171.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The range of exogenous agents likely to affect, generally detrimentally, the normal development of the brain and central nervous system defies estimation although the amount of accumulated evidence is enormous. The present review is limited to certain types of chemotherapeutic and "use-and-abuse" compounds and environmental agents, exemplified by anesthetic, antiepileptic, sleep-inducing and anxiolytic compounds, nicotine and alcohol, and stress as well as agents of infection; each of these agents have been investigated quite extensively and have been shown to contribute to the etiopathogenesis of serious neuropsychiatric disorders. To greater or lesser extent, all of the exogenous agents discussed in the present treatise have been investigated for their influence upon neurodevelopmental processes during the period of the brain growth spurt and during other phases uptill adulthood, thereby maintaining the notion of critical phases for the outcome of treatment whether prenatal, postnatal, or adolescent. Several of these agents have contributed to the developmental disruptions underlying structural and functional brain abnormalities that are observed in the symptom and biomarker profiles of the schizophrenia spectrum disorders and the fetal alcohol spectrum disorders. In each case, the effects of the exogenous agents upon the status of the affected brain, within defined parameters and conditions, is generally permanent and irreversible.
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Affiliation(s)
- Trevor Archer
- Department of Psychology, University of Gothenburg, Gothenburg, Sweden.
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Rech RL, de Lima MNM, Dornelles A, Garcia VA, Alcalde LA, Vedana G, Schröder N. Reversal of age-associated memory impairment by rosuvastatin in rats. Exp Gerontol 2010; 45:351-6. [DOI: 10.1016/j.exger.2010.02.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Revised: 01/31/2010] [Accepted: 02/02/2010] [Indexed: 01/08/2023]
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Physical exercise attenuates MPTP-induced deficits in mice. Neurotox Res 2010; 18:313-27. [PMID: 20300909 DOI: 10.1007/s12640-010-9168-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Revised: 01/27/2010] [Accepted: 02/24/2010] [Indexed: 10/19/2022]
Abstract
Two experiments were performed to investigate the effects of physical exercise upon the hypokinesia induced by two different types of MPTP administration to C57/BL6 mice. In the first, mice were administered either the standard MPTP dose (2 × 20 or 2 × 40 mg/kg, 24-h interval) or vehicle (saline, 5 ml/kg); and over the following 3 weeks were given daily 30-min period of wheel running exercise over five consecutive days/week or placed in a cage in close proximity to the running wheels. Spontaneous motor activity testing in motor activity test chambers indicated that exercise attenuated the hypokinesic effects of both doses of MPTP upon spontaneous activity or subthreshold L: -Dopa-induced activity. In the second experiment, mice were either given wheel running activity on four consecutive days (30-min period) or placed in a cage nearby and on the fifth day, following motor activity testing over 60 min, injected with either MPTP (1 × 40 mg/kg) or vehicle. An identical procedure was maintained over the following 4 weeks with the exception that neither MPTP nor vehicle was injected after the fifth week. The animals were left alone (without either exercise or MPTP) and tested after 2- and 4-week intervals. Weekly exercise blocked, almost completely, the progressive development of severe hypokinesia in the MPTP mice and partially restored normal levels of activity after administration of subthreshold L: -Dopa, despite the total absence of exercise following the fifth week. In both experiments, MPTP-induced loss of dopamine was attenuated by the respective regime of physical exercise with dopamine integrity more effectively preserved in the first experiment. The present findings are discussed in the context of physical exercise influences upon general plasticity and neuroreparative propensities as well as those specific for the nigrostriatal pathway.
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Luchtman DW, Shao D, Song C. Behavior, neurotransmitters and inflammation in three regimens of the MPTP mouse model of Parkinson's disease. Physiol Behav 2009; 98:130-8. [DOI: 10.1016/j.physbeh.2009.04.021] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2009] [Revised: 04/24/2009] [Accepted: 04/27/2009] [Indexed: 01/19/2023]
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16
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Rhodes SL, Ritz B. Genetics of iron regulation and the possible role of iron in Parkinson's disease. Neurobiol Dis 2008; 32:183-95. [PMID: 18675357 DOI: 10.1016/j.nbd.2008.07.001] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 07/01/2008] [Accepted: 07/02/2008] [Indexed: 12/21/2022] Open
Abstract
Parkinson's disease (PD) is acknowledged as the second most common neurodegenerative disorder after Alzheimer's Disease. Older age may be the only unequivocal risk factor for PD although the male to female ratio is consistently greater than 1 in populations of European ancestry. Characteristic features of PD include dopaminergic neuron death in the substantia nigra (SN) pars compacta, accumulation of alpha-synuclein inclusions known as Lewy bodies in the SN, and brain iron accumulation beyond that observed in non-PD brains of a similar age. In this review article, we will provide an overview of human and animal studies investigating the contributions of iron in PD, a summary of human studies of iron-related genes in PD, a review of the literature on the genetics of iron metabolism, and some hypotheses on possible roles for iron in the pathogenic processes of PD including potential interactions between iron and other factors associated with Parkinson's disease.
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Affiliation(s)
- Shannon L Rhodes
- Medical Genetics Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.
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Archer T, Fredriksson A. Functional consequences of iron overload in catecholaminergic interactions: the Youdim factor. Neurochem Res 2007; 32:1625-39. [PMID: 17694434 DOI: 10.1007/s11064-007-9358-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2006] [Accepted: 04/13/2007] [Indexed: 01/06/2023]
Abstract
The influence of postnatal iron overload upon implications of the functional and interactive role of dopaminergic and noradrenergic pathways that contribute to the expressions of movement disorder and psychotic behaviours in mice was studied in a series of experiments. (1) Postnatal iron overload at doses of 7.5 mg/kg (administered on Days 10-12 post partum) and above, invariably induced a behavioural syndrome consisting of an initial (1st 20-40 min of a 60-min test session) hypoactivity followed by a later (final 20 min of a 60-min test session) hyperactivity, when the mice were tested at adult ages (age 60 days or more). (2) Following postnatal iron overload, subchronic treatment with the neuroleptic compounds, clozapine and haloperidol, dose-dependently reversed the initial hypoactivity and later hyperactivity induced by the metal. Furthermore, DA D(2) receptor supersensitivity (as assessed using the apomorphine-induced behaviour test) was directly and positively correlated with iron concentrations in the basal ganglia. (3) Brain noradrenaline (NA) denervation, using the selective NA neurotoxin, DSP4, prior to administration of the selective DA neurotoxin, MPTP, exacerbated both the functional (hypokinesia) and neurochemical (DA depletion) effects of the latter neurotoxin. Treatment with L-Dopa restored motor activity only in the animals that had not undergone NA denervation. These findings suggest an essential neonatal iron overload, termed "the Youdim factor", directing a DA-NA interactive component in co-morbid disorders of nigrostriatal-limbic brain regions.
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Affiliation(s)
- Trevor Archer
- Department of Neuroscience & Psychiatry, Ulleråker, University of Uppsala, Uppsala, 750 17, Sweden.
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Fredriksson A, Archer T. Subchronic administration of haloperidol influences the functional deficits of postnatal iron administration in mice. Neurotox Res 2007; 10:123-9. [PMID: 17062374 DOI: 10.1007/bf03033241] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
C57/BL6 mice were administered either 7.5 mg Fe(2+) (II)/ kg or vehicle (saline) postnatally on Days 10-12 after birth. From 64 days of age onwards for 24 days, groups of mice were administered either haloperidol (0.25 or 1 or 2 mg/kg, s.c.) or vehicle (Tween-80). Twenty-four hours after the final injection of either neuroleptic compound or vehicle, spontaneous motor activity was measured over a 60-min interval. Postnatal Fe(2+)-treatment (7.5 mg/kg, postnatally) reduced motor activity parameters during the initial 20-min periods (0-20 and 20-40 min) and then induced hyperactivity during the final 20-min period over all three parameters of activity, confirming previous observations. Subchronic administration of haloperidol, at the 1 and 2 mg/kg doses, and to a lesser extent the 0.25 mg/kg dose, increased the levels of activity in all three motor activity parameters in postnatal iron-treated mice: locomotion (1st and 2nd 20 min periods), rearing (1st and 2nd 20 min periods) and total activity (1st 20 min period). All three doses of haloperidol abolished the later hyperactivity in iron-treated mice, with the exception of the 0.25 mg/kg dose with regard to rearing behaviour. Apomorphine (1 mg/kg, s.c.)-induced activity was elevated by postnatal iron administration and by subchronic administration of apomorphine at the higher dose levels. In the context of these and other observations, it is suggested that subchronic administration of haloperidol interacting with postnatal iron induces different expressions of dopamine neuron comorbidity underlying movement disorder.
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Affiliation(s)
- A Fredriksson
- University of Uppsala, Department of Neuroscience and Psychiatry, Ulleraker, SE-750 17 Uppsala, Sweden
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19
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Fredriksson A, Archer T. Postnatal iron overload destroys NA-DA functional interactions. J Neural Transm (Vienna) 2006; 114:195-203. [PMID: 16932993 DOI: 10.1007/s00702-006-0522-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2005] [Accepted: 05/05/2006] [Indexed: 10/24/2022]
Abstract
C57/BL6 mice were administered either postnatal iron (Fe(2+) 7.5 mg/kg, on postnatal days 10-12) or vehicle, followed by administration of either DSP4 (50 mg/kg, s.c., 30 min after injection of zimeldine, 20 mg/kg, s.c.) or vehicle (saline) at 63 days of age. Three weeks later, iron/vehicle treated, DSP4/vehicle treated mice were injected with either a low dose of MPTP (2 x 20 mg/kg, with a 24-hr interval between injections) or vehicle. Behaviour testing took place a further three weeks (spontaneous behaviour and L-Dopa induced) and two weeks (clonidine-L-Dopa induced) later. Postnatal iron administration exacerbated the bradykinesia induced by MPTP and virtually abolished all spontaneous motor activity in NA-denervated mice that were MPTP-treated. Postnatal iron administration reduced markedly the restoration of motor activity by suprathreshold L-Dopa (20 mg/kg) following a 60-min habituation to the test chambers. Pretreatment with DSP4 effectively eliminated the restorative effect of L-Dopa in the MPTP mice. The synergistic effects of co-administration of clinidine (1 mg/kg) with a subthreshold dose of L-Dopa (5 mg/kg) in elevating the motor activity of MPTP mice were reduced markedly by postnatal iron administration, as well as by pretreatment with DSP4. NA-denervation by DSP4, after postnatal iron treatment, totally abolished the activity-elevating effects of the alpha-adrenoceptor agonist + DA-precursor combination in MPTP mice, and virtually eliminated these effects in saline (non-MPTP) mice. Postnatal iron administration caused enduring higher levels of total iron content in all the groups with an increased level in mice treated with DSP4 followed by MPTP. These divergent findings confirm the direct influence of NA innervation upon dopaminergic functional expression and indicate a permanent vulnerability both in the noradrenergic and dopaminergic pathways following the postnatal infliction of an iron overload.
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Affiliation(s)
- A Fredriksson
- Department of Neuroscience, Psychiatry Ulleråker, University of Uppsala, Uppsala, Sweden
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20
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Fredriksson A, Archer T. Subchronic administration of haloperidol influences the functional deficits of postnatal iron administration in mice. Neurotox Res 2006; 9:305-12. [PMID: 16782590 DOI: 10.1007/bf03033321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
C57/BL6 mice were administered either 7.5 mg Fe (II)/ kg or vehicle (saline) postnatally on Days 10-12 after birth. From 64 days of age onwards for 24 days, groups of mice were administered either haloperidol (0.25 or 1 or 2 mg/kg, s.c.) or vehicle (Tween-80). Twenty-four hours after the final injection of either neuroleptic compound or vehicle, spontaneous motor activity was measured over a 60-min interval. Postnatal Fe (II)-treatment (7.5 mg/kg, postnatally) reduced motor activity parameters during the initial 20-min periods (0-20 and 20-40 min) and then induced hyperactivity during the final 20-min period over all three parameters of activity, confirming previous observations. Subchronic administration of haloperidol, at the 1 and 2 mg/kg doses, and to a lesser extent the 0.25 mg/kg dose, increased the levels of activity in all three motor activity parameters in postnatal iron-treated mice: locomotion (1st and 2nd 20 min periods), rearing (1st and 2nd 20 min periods) and total activity (1st 20 min period). All three doses of haloperidol abolished the later hyperactivity in iron-treated mice, with the exception of the 0.25 mg/kg dose with regard to rearing behaviour. Apomorphine (1 mg/kg, s.c.) -induced activity was elevated by postnatal iron administration and by subchronic administration of apomorphine at the higher dose levels. In the context of these and other observations, it is suggested that subchronic administration of haloperidol interacting with postnatal iron induces different expressions of dopamine neuron comorbidity underlying movement disorder.
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Affiliation(s)
- Anders Fredriksson
- University of Uppsala, Department of Neuroscience AND Psychiatry, Ulleraker, SE-750 17 Uppsala, Sweden
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21
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Isaac G, Fredriksson A, Danielsson R, Eriksson P, Bergquist J. Brain lipid composition in postnatal iron-induced motor behavior alterations following chronic neuroleptic administration in mice. FEBS J 2006; 273:2232-43. [PMID: 16649999 DOI: 10.1111/j.1742-4658.2006.05236.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Several studies have shown that deficient uptake or excessive break down of membrane phospholipids may be associated with neurodegenerative and psychiatric disorders. The purpose of the present study was to examine the effects of postnatal iron administration in lipid composition and behavior and whether or not the established effects may be altered by subchronic administration of the neuroleptic compounds, clozapine and haloperidol. In addition to motor activities such as locomotion, rearing and activity, a targeted lipidomics approach has been used to investigated the brains of eight groups of mice (four vehicle groups and four iron groups) containing six individuals in each group treated with vehicle, low dose clozapine, high dose clozapine and haloperidol. Lipids were extracted by the Folch method and analyzed using reversed-phase capillary liquid chromatography coupled on-line to electrospray ionization mass spectrometry (LC/ESI/MS). Identification of phosphatidylcholine (PC) and sphingomyelin (SM) molecular species was based on their retention time, m/z ratio, head group specific up-front fragmentation and analysis of the product ions produced upon fragmentation. A comparison between the Ve-groups and Fe-groups showed that levels of PC and SM molecular species and motor activities were significantly lower in Fe-Ve compared to Ve-Ve. The effects of neuroleptic treatment with and without iron supplementation were studied. In conclusion our results support the hypothesis that an association between psychiatric disorders and lipid and behavior abnormalities in the brain exists.
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Affiliation(s)
- Giorgis Isaac
- Department of Analytical Chemistry, Biomedical Center, Uppsala University, Sweden
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22
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Kaur D, Peng J, Chinta SJ, Rajagopalan S, Di Monte DA, Cherny RA, Andersen JK. Increased murine neonatal iron intake results in Parkinson-like neurodegeneration with age. Neurobiol Aging 2006; 28:907-13. [PMID: 16765489 DOI: 10.1016/j.neurobiolaging.2006.04.003] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2006] [Revised: 03/30/2006] [Accepted: 04/04/2006] [Indexed: 11/21/2022]
Abstract
Iron elevation is well-documented in the Parkinsonian midbrain but its cause and contribution to subsequent neurodegeneration remain unknown. Mice administered iron at doses equivalent to those found in iron-fortified human infant formula during a developmental period equivalent to the first human year of life display progressive midbrain neurodegeneration and enhanced vulnerability to toxic injury. This may have major implications for the impact of neonatal iron intake as a potential risk factor for later development of Parkinson's disease (PD).
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23
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Archer T, Fredriksson A. Influence of noradrenaline denervation on MPTP-induced deficits in mice. J Neural Transm (Vienna) 2005; 113:1119-29. [PMID: 16362627 DOI: 10.1007/s00702-005-0402-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Accepted: 10/09/2005] [Indexed: 10/25/2022]
Abstract
C57/BL6 mice were administered either DSP4 (50 mg/kg, s.c., 30 min after injection of zimeldine, 20 mg/kg, s.c.) or vehicle (saline) at 63 days of age. Three weeks later, one group (n = 10) of DSP4-treated and one group of vehicle-treated mice were administered MPTP (2 x 40 mg/kg, s.c., 24 hours between injections; the High dose groups), one group (n = 10) of DSP4-treated and one group of vehicle-treated mice were administered MPTP (2 x 20 mg/kg, s.c., 24 hours between injections; the Low dose groups), and one group (n = 10) of DSP4-treated and one group of vehicle-treated mice were administered vehicle. Three weeks later, all six groups were tested in motor activity test chambers, followed by injections of L-Dopa (20 mg/kg, s.c.), and then tested over a further 360 min in the activity test chambers. It was found that pretreatment with the selective NA neurotoxin, DSP4, deteriorated markedly the dose-dependent motor activity deficits observed in the vehicle pretreated MPTP treated mice. These 'ultra-deficits' in the spontaneous motor behaviour of MPTP-treated mice were observed over all three parameters: locomotion, rearing and total activity, and were restricted to the 1(st) and 2(nd) 20-min periods. Administration of L-Dopa (20 mg/kg) following the 60-min testing of spontaneous behaviour restored the motor activity of Vehicle + MPTP treated mice (neither the Vehicle + MPTP-Low nor the Vehicle + MPTP-High groups differed from the Vehicle-Vehicle group, here) but failed to do so in the DSP4 pretreated mice. Here, a dose-dependent deficit of L-Dopa-induced motor activity (over all three parameters) was obtained thereby offering further evidence of an 'ultra-deficit' of function due to previous denervation of the NA terminals. The present findings support the notion that severe damage to the locus coeruleus noradrenergic system, through systemic DSP4, disrupts the facilitatory influence on the nigrostriatal DA system, and interferes with the ability of the nigrostriatal pathway to compensate for or recover from marked injury, MPTP treatment.
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Affiliation(s)
- T Archer
- Department of Psychology, University of Göteborg, Göteborg, Sweden.
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24
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Fredriksson A, Eriksson P, Archer T. Postnatal iron-induced motor behaviour alterations following chronic neuroleptic administration in mice. J Neural Transm (Vienna) 2005; 113:137-50. [PMID: 16082515 DOI: 10.1007/s00702-005-0307-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2004] [Accepted: 03/19/2005] [Indexed: 10/25/2022]
Abstract
C57/BL6 mice were administered either 7.5 mg Fe(2+)/kg or vehicle (saline) postnatally on days 10-12 after birth. From 61 days of age onwards for 21 days, groups of mice were administered either clozapine (1 or 5 mg/kg, s.c.) or haloperidol (1 mg/kg, s.c.) or vehicle (Tween-80). Twenty-four hours after the final injection of either neuroleptic compound or vehicle, spontaneous motor activity was measured over a 60-min interval. Following this, each animal was removed, injected apomorphine (1 mg/kg, s.c.) and replaced in the same test chamber. It was found that postnatal administration of Fe(2+) at the 7.5 mg/kg dose level reduced activity during the initial 20-min periods (0-20 and 20-40 min) and then induced hyperactivity during the final 20-min period over all three parameters of activity. Subchronic treatment with the higher, 5 mg/kg, dose of clozapine abolished or attenuated the hypoactivity in by postnatal Fe(2+) during the 1(st) two 20-min periods over all three parameters of activity. Subchronic treatment with the higher, 5 mg/kg, dose of clozapine abolished or attenuated the hyperactivity in by postnatal Fe(2+) during the 3(rd) and final 20-min period. Subchronic administration of haloperidol, without postnatal iron, increased the level of both locomotion (1(st) 20 min) and rearing (2(nd) 20 min) activity. Postnatal administration of Fe(2+) at the 7.5 mg/kg dose increased the levels of both locomotion and rearing, but not total activity, following administration of apomorphine (1 mg/kg). Subchronic administration of clozapine, at both the 1 and 5 mg/kg doses, reduced the increased locomotor activity caused by postnatal Fe(2+), whereas clozapine, 5 mg/kg, elevated further the postnatal Fe(2+)-induced increased in rearing. Subchronic administration of clozapine, at both the 1 and 5 mg/kg doses, and haloperidol, 1 mg/kg, increased the level of locomotor following administration of apomorphine (1 mg/kg) in mice treated postnatally with vehicle, whereas only clozapine increased the level of rearing. Correlational analyses indicated that both apomorphine-induced locomotion and rearing were highly correlated with the total iron content in the basal ganglia, thereby offering direct evidence of the linear relationship between iron content in the basal ganglia and the behavioural expression of DA D(2)-receptor supersensitivity in mice.
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Affiliation(s)
- A Fredriksson
- Department of Neuroscience and Psychiatry, University of Uppsala, Uppsala, Sweden
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25
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Fredriksson A, Archer T, Alm H, Gordh T, Eriksson P. Neurofunctional deficits and potentiated apoptosis by neonatal NMDA antagonist administration. Behav Brain Res 2004; 153:367-76. [PMID: 15265631 DOI: 10.1016/j.bbr.2003.12.026] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2003] [Revised: 12/15/2003] [Accepted: 12/15/2003] [Indexed: 10/26/2022]
Abstract
The early postnatal brain development, when many potentially sensitive processes occur, has been shown to be vulnerable to different pharmacological and environmental compounds. In the present investigation, four groups of neonatal NMRI male mice were administered the glutamate NMDA receptor antagonist ketamine (50 mg/kg, s.c.), or the GABA(A) receptor agonist diazepam (5 mg/kg, s.c.), or co-administered ketamine (50 mg/kg, s.c.) and diazepam (5 mg/kg, s.c.), or vehicle (0.9% saline, s.c.) on day 10 after birth. On day 11, mice from each treatment group were sacrificed and brains were taken for analysis of neuronal cell degeneration, using Fluoro-Jade staining technique. Ketamine, but not diazepam, induced a severe degeneration of cells in the parietal cortex. The opposite was observed for diazepam in the laterodorsal thalamus. The most pronounced cell degeneration was seen in parietal cortex of mice exposed to both ketamine and diazepam. At 2 months of age each treatment group was tested for motor activity and learning performance. Ketamine and ketamine + diazepam treated mice displayed severe deficits of habituation to the test chamber in the spontaneous motor activity test, marked deficits of acquisition learning and retention memory in the radial arm maze-learning task and less shift learning in the circular swim maze-learning task. This study indicates that the observed functional deficits can be related to cell degeneration induced during a critical stage of neonatal brain development. The potentiated apoptosis induced by ketamine and diazepam may have implications for the selection of drugs used in neonatal paediatric anaesthesia.
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Affiliation(s)
- Anders Fredriksson
- Department of Neuroscience, Psychiatry Ulleråker, Uppsala University, SE-750 17 Uppsala, Sweden.
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26
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Kaur D, Andersen J. Does cellular iron dysregulation play a causative role in Parkinson's disease? Ageing Res Rev 2004; 3:327-43. [PMID: 15231240 DOI: 10.1016/j.arr.2004.01.003] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2004] [Accepted: 01/20/2004] [Indexed: 10/26/2022]
Abstract
Selective dopaminergic cell loss in Parkinson's disease is correlated with increased levels of cellular iron. It is still hotly debated as to whether the increase in iron is an upstream event which acts to promote neurodegeneration via formation of oxidative stress or whether iron accumulates as a by-product of the neuronal cell loss. Here we review evidence for loss of iron homeostasis as a causative factor in disease-associated neurodegeneration and the primary players which may be involved. A series of recent studies suggest that iron regulatory proteins (IRPs) coordinate both cellular iron levels and energy metabolism, both of which are disrupted in Parkinson's disease (PD) and may in turn contribute to increased levels of oxidative stress associated with the disease. Iron has also been recently been implicated in promotion of alpha-synuclein aggregation either directly or via increasing levels of oxidative stress suggesting an important role for it in Lewy body formation, another important hallmark of the disease.
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Affiliation(s)
- Deepinder Kaur
- Buck Institute for Aging Research, 8001 Redwood Blvd, Novato, CA 94945, USA
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Fredriksson A, Archer T. Neurobehavioural deficits associated with apoptotic neurodegeneration and vulnerability for ADHD. Neurotox Res 2004; 6:435-56. [PMID: 15639778 DOI: 10.1007/bf03033280] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Several studies involving postnatal administration of the N-methyl-D-aspartate (NMDA) antagonists, dizocilpine (MK-801; 3 x 0.5 mg/kg, at 08.00, 16.00 and 24.00 h) on Postnatal day 11, or Ketamine (1 x 50 mg/kg) or Ethanol (1 x 2.5 g/kg, Ethanol-Low, or 2 x 2.5 g/kg, 2-h interval, Ethanol-High) on Postnatal day 10, are described. Some mice from each treatment/vehicle group were sacrificed 24 h after NMDA antagonist treatment and brain regions were taken for fluoro-jade staining analysis. Functional analysis was initiated at 60 days of age. All three treatments inducing an antagonistic action at NMDA receptors, MK-801, Ketamine and Ethanol-High induced a similar pattern of initial hypoactivity followed by marked and lasting hyperactivity in the motor activity test chambers. In each case, the basal hyperactivity level was abolished by acute treatment with a low dose of D-amphetamine (0.25 mg/kg). All three treatments, MK-801, Ketamine and Ethanol-High, induced a deficit in acquisitive performance in the radial arm maze test of instrumental learning. The deficit induced by postnatal MK-801 was abolished by acute treatment with the low dose of D-amphetamine. All three treatments, MK-801, Ketamine and Ethanol-High, resulted in normal acquisitive performance during the first three test days in the circular swim with the submerged platform maintained in a constant position, but on the fourth test day, with the platform position shifted to a different "quadrant", induced marked deficits. Fluoro-jade staining analyses indicated a devastating cell degeneration in several brain regions of mice administered NMDA antagonists postnatally, including the hippocampus, frontal cortex, parietal cortex, and cerebellum. Severe cell degeneration in the laterodorsal thalamus due to Ethanol or diazepam (5 mg/kg) appeared not to affect the different aspects of function. The pattern of dysfunctional outcome and apoptotic cell loss following postnatal NMDA antagonist treatment offers a plausible similarity to the major aspects of 'syndromatic continuity' in ADHD, hyperactivity, inattention and impulsivity, thereby providing an interesting animal model of the disorder.
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Affiliation(s)
- Anders Fredriksson
- Department of Neuroscience and Psychiatry, University of Uppsala, Ulleraker, SE-750 17 Uppsala, Sweden
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28
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Youdim MBH. What have we learnt from CDNA microarray gene expression studies about the role of iron in MPTP induced neurodegeneration and Parkinson's disease? JOURNAL OF NEURAL TRANSMISSION. SUPPLEMENTUM 2003:73-88. [PMID: 12946050 DOI: 10.1007/978-3-7091-0643-3_5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
There have been numerous hypotheses concerning the etiology and mechanism of dorsal raphe dopaminergic neurodegeneration in Parkinson's disease and its animal models, MPTP (N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) and 6-hydroxydopamine. The advent of cDNA microarray gene expression where expression of thousands of genes can be globally assessed has indicated that mechanism of neurodegeneration by MPTP is a complex cascade of vicious circles. One of these is the alteration of genes associated with iron metabolism, a transitional metal closely associated with inducing the formation of reactive oxygen species and inducing oxidative stress. cDNA gene expression analyses support the established hypothesis of oxidative induced neurodegeneration involving iron deposition in substantia nigra pars compacta (SNPC) parkinsonian brains. The regulation of cellular iron metabolism has been further enhanced by the recent discovery of two iron regulatory proteins, IRP1 and IRP2 which control the level of iron with in the cell. When the cellular level of iron increases IRP2 is degraded by ubiquitination and no further iron accumulates. The reverse occurs when the level of iron is low within the cell. Knock-out IRP1 and IRP2 mice have shown that in latter mice brain iron accumulation precedes the neurodegeneration, ataxia and bradykinesia observed in these animals. Indeed MPTP treatment, which results in iron accumulation in SNCP, abolishes IRP2 with the concomitant increase in alpha-synuclein. Iron chelators such as R-apomorphine and EGCG, which protect against MPTP neurotoxicity, prevent the loss of IRP2 and the increase in alpha-synuclein. The presence of iron together with alpha-synuclein in SNPC may be detrimental for dopaminergic neurons. Since, iron has been shown to cause aggregation of alpha-synuclein to a neurotoxic agent. The use of iron chelators penetrating the blood brain barrier as neuroprotective drugs has been envisaged.
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Affiliation(s)
- M B H Youdim
- Eve Topf and National Parkinson Foundation Centers Of Excellence For Neurodegenerative Diseases Research, and Department of Pharmacology, Technion-Faculty of Medicine, Haifa, Israel.
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Fredriksson A, Archer T. Effect of postnatal iron administration on MPTP-induced behavioral deficits and neurotoxicity: behavioral enhancement by L-Dopa-MK-801 co-administration. Behav Brain Res 2003; 139:31-46. [PMID: 12642174 DOI: 10.1016/s0166-4328(02)00035-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Two experiments were performed to investigate the interactive effects of postnatal iron administration and adult MPTP treatment upon the function of C57 Bl/6 mice tested at adult age and to ascertain the possible ameliatory effects of a subthreshold dose of L-Dopa co-administered with different doses of the uncompetitive glutamate antagonist, MK-801. Experiment I indicated that postnatal iron induced marked deficits (hypoactivity), initially, in all three parameters of motor activity at the 5.0 and 7.5 mg/kg doses, and to a lesser extent at the 2.5 mg/kg dose. Later combination with MPTP (2x40 mg/kg) potentiated severely these deficits. During the final period of testing a marked hyperactivity was obtained for the two higher dose groups; this effect was abolished in mice administered MPTP. Experiment II indicated that the deficits in motor activity parameters induced by postnatal iron at 7.5 mg/kg were alleviated in a dose-related manner by the co-administration of the uncompetitive glutamate antagonist, MK-801, with a subthreshold dose of L-Dopa. Postnatal iron (7.5 mg/kg) administration followed by low doses of MPTP (2x20 mg/kg) 3 months later virtually abolished all motor activity. The combination of these compounds increased also the motor activity of mice treated with MPTP (2x20 mg/kg) or mice treated with the combination of postnatal iron and MPTP. The combination of MK-801 with L-Dopa increased locomotor (0.3 mg/kg), rearing (0.1 and 0.3 mg/kg) and total activity (0.3 mg/kg) of iron-treated mice during the initial, hypoactive 30-min period of testing. Locomotor activity (0.1 mg/kg) of MPTP-treated mice was increased too during this period. During the final 30-min period of testing all three parameters of activity (locomotion, 0.3 mg/kg; rearing and total activity, 0.1 and 0.3 mg/kg) were enhanced in the iron-treated mice, locomotion (0.1 mg/kg) and rearing (0.1 mg/kg) in the iron plus MPTP treated mice and only locomotion (0.1 mg/kg) in the MPTP-treated mice. In control mice (vehicle+saline), the higher doses of MK-801 (0.1 and 0.3 mg/kg) enhanced both locomotor and total activity. Analyses of total iron concentration in the frontal cortex and basal ganglia of Fe(2+) and vehicle treated mice indicated that marked elevations basal ganglia iron levels of the 5.0 and 7.5 mg/kg groups, later injected either saline or MPTP, were obtained (Experiment I). In Experiment II, iron concentrations in the basal ganglia were elevated in both the Fe(2+)-sal and Fe(2+)-MPTP groups to 170 and 177% of Veh.-sal values, respectively. There was a significant increase in the frontal cortex of iron-treated mice later administered either saline or MPTP (2x40 mg/kg) in Experiment I as well as in those given iron followed by MPTP (2x20mg/kg) in Experiment II. The implications of iron overload in parkinsonism seem confirmed by the interactive effects of postnatal administration of the metal followed by adult MPTP treatment upon motor activity and the activity-enhancing effects of co-administration of L-Dopa with MK-801.
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Affiliation(s)
- Anders Fredriksson
- Department of Neuroscience and Psychiatry, University of Uppsala, Ulleråker, SE-750 17, Uppsala, Sweden
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Archer T, Schröder N, Fredriksson A. Neurobehavioural deficits following postnatal iron overload: II Instrumental learning performance. Neurotox Res 2003; 5:77-94. [PMID: 14628858 DOI: 10.1007/bf03033374] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Palomo T, Beninger RJ, Kostrzewa RM, Archer T. Brain sites of movement disorder: genetic and environmental agents in neurodevelopmental perturbations. Neurotox Res 2003; 5:1-26. [PMID: 12832221 DOI: 10.1007/bf03033369] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In assessing and assimilating the neurodevelopmental basis of the so-called movement disorders it is probably useful to establish certain concepts that will modulate both the variation and selection of affliction, mechanisms-processes and diversity of disease states. Both genetic, developmental and degenerative aberrations are to be encompassed within such an approach, as well as all deviations from the necessary components of behaviour that are generally understood to incorporate "normal" functioning. In the present treatise, both conditions of hyperactivity/hypoactivity, akinesia and bradykinesia together with a constellation of other symptoms and syndromes are considered in conjunction with the neuropharmacological and brain morphological alterations that may or may not accompany them, e.g. following neonatal denervation. As a case in point, the neuroanatomical and neurochemical points of interaction in Attention Deficit and Hyperactivity disorder (ADHD) are examined with reference to both the perinatal metallic and organic environment and genetic backgrounds. The role of apoptosis, as opposed to necrosis, in cell death during brain development necessitates careful considerations of the current explosion of evidence for brain nerve growth factors, neurotrophins and cytokines, and the processes regulating their appearance, release and fate. Some of these processes may possess putative inherited characteristics, like alpha-synuclein, others may to greater or lesser extents be endogenous or semi-endogenous (in food), like the tetrahydroisoquinolines, others exogenous until inhaled or injested through environmental accident, like heavy metals, e.g. mercury. Another central concept of neurodevelopment is cellular plasticity, thereby underlining the essential involvement of glutamate systems and N-methyl-D-aspartate receptor configurations. Finally, an essential assimilation of brain development in disease must delineate the relative merits of inherited as opposed to environmental risks not only for the commonly-regarded movement disorders, like Parkinson's disease, Huntington's disease and epilepsy, but also for afflictions bearing strong elements of psychosocial tragedy, like ADHD, autism and Savantism.
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Affiliation(s)
- T Palomo
- Servicio de Psiquiatria, Hospital 12 de Octobre, Ctra. Andalucia Km. 5,400, 28041 Madrid, Spain.
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Gerlach M, Double KL, Ben-Shachar D, Zecca L, Youdim MBH, Riederer P. Neuromelanin and its interaction with iron as a potential risk factor for dopaminergic neurodegeneration underlying Parkinson's disease. Neurotox Res 2003; 5:35-44. [PMID: 12832223 DOI: 10.1007/bf03033371] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Neuromelanin (NM) is a granular, dark brown pigment produced in some but not all of the dopaminergic neurons of the human substantia nigra (SN). In Parkinson's disease (PD) the pigmented dopaminergic neurons of the SN degenerate, suggesting that this process is related to the presence of NM. As yet it is unknown whether NM in the parkinsonian brain differs from that found in healthy tissue and thus may fulfil a different role within this tissue. The function of NM within the pigmented neurons is unknown but other melanins are believed to play a protective role via attenuation of free radical damage. Experimental evidence suggests that NM may also exhibit this characteristic, possibly by direct inactivation of free radical species or via its ability to chelate transition metals, such as iron. NM has the ability to bind a variety of metals, seven per cent of isolated NM is reported to consist of Fe, Cu, Zn and Cr. Iron is of particular interest as this metal is highly concentrated within the SN. Up to 20 per cent of the total iron contained in the SN from normal subjects is bound within NM. Further, it was demonstrated that NM contains a protein component and that iron is bound to NM in the ferric form. Increased tissue iron found in the parkinsonian SN may saturate iron-chelating sites on NM, and a looser association between iron and NM may result in an increased, rather than decreased, production of free radical species. It is hypothesized that this redox-active iron could be released and involved in a Fenton-like reaction leading to an increased production of oxidative radicals. The resultant radical-mediated cytotoxicity may contribute to cellular damage observed in PD.
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Affiliation(s)
- Manfred Gerlach
- Clinical Neurochemistry, Department of Child and Youth Psychiatry and Psychotherapy, University of Würzburg, Füchsleinstrasse 15, D-97080 Würzburg, Germany.
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Fredriksson A, Schröder N, Archer T. Neurobehavioural deficits following postnatal iron overload: I spontaneous motor activity. Neurotox Res 2003; 5:53-76. [PMID: 14628856 DOI: 10.1007/bf03033373] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Fredriksson A, Archer T. Hyperactivity following postnatal NMDA antagonist treatment: reversal by D-amphetamine. Neurotox Res 2003; 5:549-64. [PMID: 14715439 DOI: 10.1007/bf03033165] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Three experiments were performed to study the effects of neonatal administration of glutamate receptor antagonists, on either Day 11 (dizocilpine = MK-801, 3 x 0.5 mg/kg, s.c., injected at 0800, 1600 and 2400 h) or Day 10 (Ketamine, 1 x 50 mg/kg, s.c., or Ethanol-Low, 1 x 2.5 mg/kg, or, Ethanol-High, 2 x 2.5 mg/kg, s.c., with 2-h interval) to male mice pups, on spontaneous motor behavior, habituation to a novel situation and D-amphetamine-induced activity in the adult animals. Mice administered MK-801 showed initial hypoactivity followed by hyperactivity over the later (20-40 and 40-60 min) periods of testing. Mice administered Ketamine and Ethanol-High similarly displayed an initial hypoactivity followed by hyperactivity over the later time (20-60 min) of testing. Habituation to the novel activity test chambers was reduced drastically in the MK-801 mice compared with vehicle-treated mice. Similarly, mice administered Ketamine and Ethanol-High displayed too drastically reduced habituation behavior. The low dose of D-amphetamine (0.25 mg/kg) reduced the hyperactivity of neonatal MK-801-treated mice, particularly from 30-60 min onwards, and elevated the activity level of the vehicle-treated mice. Similarly, the low dose of D-amphetamine (0.25 mg/kg) reduced the hyperactivity of neonatally Ketamine-treated and Ethanol-High-treated mice, particularly from 30-60 min onwards, and elevated the activity level of the respective vehicle-treated mice. Fluoro-jade staining per mm(2) regional brain tissue of MK-801 mice pups expressed as percent of vehicle mice pups showed also that the extensiveness of staining was markedly greater in the parietal cortex, hippocampus, frontal cortex, and lesser so in the laterodorsal thalamus. Ketamine-treated mice showed cell degeneration mainly in the parietal cortex, whereas the Ethanol-High mice showed marked cell degeneration in both the parietal and laterodorsal cortex. The present findings that encompass a pattern of regional neuronal degeneration, disruptions of spontaneous motor activity, habituation deficits and reversal of hyperactivity by a low dose of D-amphetamine suggest a model of Attention Deficit Hyperactivity Disorder that underlines the intimate role of N-methyl-D-aspartate (NMDA) receptors in the developing brain.
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Affiliation(s)
- Anders Fredriksson
- University of Uppsala, Department of Neuroscience and Psychiatry, Ulleråker, SE-750 17 Uppsala, Sweden
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Double KL, Ben-Shachar D, Youdim MBH, Zecca L, Riederer P, Gerlach M. Influence of neuromelanin on oxidative pathways within the human substantia nigra. Neurotoxicol Teratol 2002; 24:621-8. [PMID: 12200193 DOI: 10.1016/s0892-0362(02)00218-0] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Neuromelanin (NM) is a dark-coloured pigment produced in the dopaminergic neurons of the human substantia nigra (SN). The function of NM within the pigmented neurons is unknown but other melanins are believed to play a protective role via attenuation of free radical damage. Experimental evidence suggests that NM may also exhibit this characteristic, possibly by directly inactivating free radical species or via its ability to chelate transition metals, such as iron. Increased tissue iron, however, may saturate iron-chelating sites on NM and a looser association between iron and NM may result in an increased, rather than decreased, production of free radical species. The death of NM-pigmented neurons in Parkinson's disease (PD) is associated with both a measurable increase in tissue iron concentrations and indices of free radical mediated damage, suggesting that NM is involved in the aetiology of this disorder. As yet, it is unknown whether NM in the parkinsonian brain differs to that found in healthy tissue and thus may fulfil a different role within this tissue.
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Affiliation(s)
- K L Double
- Prince of Wales Medical Research Institute, Barker Street, Randwick, Sydney NSW 2031, Australia.
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