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Rapid Regulation of Glutamate Transport: Where Do We Go from Here? Neurochem Res 2022; 47:61-84. [PMID: 33893911 PMCID: PMC8542062 DOI: 10.1007/s11064-021-03329-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 04/08/2021] [Accepted: 04/13/2021] [Indexed: 01/03/2023]
Abstract
Glutamate is the predominant excitatory neurotransmitter in the mammalian central nervous system (CNS). A family of five Na+-dependent transporters maintain low levels of extracellular glutamate and shape excitatory signaling. Shortly after the research group of the person being honored in this special issue (Dr. Baruch Kanner) cloned one of these transporters, his group and several others showed that their activity can be acutely (within minutes to hours) regulated. Since this time, several different signals and post-translational modifications have been implicated in the regulation of these transporters. In this review, we will provide a brief introduction to the distribution and function of this family of glutamate transporters. This will be followed by a discussion of the signals that rapidly control the activity and/or localization of these transporters, including protein kinase C, ubiquitination, glutamate transporter substrates, nitrosylation, and palmitoylation. We also include the results of our attempts to define the role of palmitoylation in the regulation of GLT-1 in crude synaptosomes. In some cases, the mechanisms have been fairly well-defined, but in others, the mechanisms are not understood. In several cases, contradictory phenomena have been observed by more than one group; we describe these studies with the goal of identifying the opportunities for advancing the field. Abnormal glutamatergic signaling has been implicated in a wide variety of psychiatric and neurologic disorders. Although recent studies have begun to link regulation of glutamate transporters to the pathogenesis of these disorders, it will be difficult to determine how regulation influences signaling or pathophysiology of glutamate without a better understanding of the mechanisms involved.
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2
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Critical Involvement of Glial Cells in Manganese Neurotoxicity. BIOMED RESEARCH INTERNATIONAL 2021; 2021:1596185. [PMID: 34660781 PMCID: PMC8514895 DOI: 10.1155/2021/1596185] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 09/16/2021] [Accepted: 09/21/2021] [Indexed: 12/13/2022]
Abstract
Over the years, most of the research concerning manganese exposure was restricted to the toxicity of neuronal cells. Manganese is an essential trace element that in high doses exerts neurotoxic effects. However, in the last two decades, efforts have shifted toward a more comprehensive approach that takes into account the involvement of glial cells in the development of neurotoxicity as a brain insult. Glial cells provide structural, trophic, and metabolic support to neurons. Nevertheless, these cells play an active role in adult neurogenesis, regulation of synaptogenesis, and synaptic plasticity. Disturbances in glial cell function can lead to neurological disorders, including neurodegenerative diseases. This review highlights the pivotal role that glial cells have in manganese-induced neurotoxicity as well as the most sounding mechanisms involved in the development of this phenomenon.
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3
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Tinkov AA, Martins AC, Avila DS, Gritsenko VA, Skalny AV, Santamaria A, Lee E, Bowman AB, Aschner M. Gut Microbiota as a Potential Player in Mn-Induced Neurotoxicity. Biomolecules 2021; 11:1292. [PMID: 34572505 PMCID: PMC8469589 DOI: 10.3390/biom11091292] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/16/2021] [Accepted: 08/26/2021] [Indexed: 12/11/2022] Open
Abstract
Manganese (Mn) is an essential metal, which at high exposures causes neurotoxic effects and neurodegeneration. The neurotoxic effects of Mn are mediated by neuroinflammation, oxidative and endoplasmic reticulum stress, mitochondrial dysfunction, and other mechanisms. Recent findings have demonstrated the potential impact of Mn overexposure on gut microbiota dysbiosis, which is known to contribute to neurodegeneration via secretion of neuroactive and proinflammatory metabolites. Therefore, in this review, we discuss the existing data on the impact of Mn exposure on gut microbiota biodiversity, bacterial metabolite production, and gut wall permeability regulating systemic levels. Recent data have demonstrated that Mn exposure may affect gut microbiota biodiversity by altering the abundance of Shiegella, Ruminococcus, Dorea, Fusicatenibacter, Roseburia, Parabacteroides, Bacteroidetes, Firmicutes, Ruminococcaceae, Streptococcaceae, and other bacterial phyla. A Mn-induced increase in Bacteroidetes abundance and a reduced Firmicutes/Bacteroidetes ratio may increase lipopolysaccharide levels. Moreover, in addition to increased systemic lipopolysaccharide (LPS) levels, Mn is capable of potentiating LPS neurotoxicity. Due to the high metabolic activity of intestinal microflora, Mn-induced perturbations in gut microbiota result in a significant alteration in the gut metabolome that has the potential to at least partially mediate the biological effects of Mn overexposure. At the same time, a recent study demonstrated that healthy microbiome transplantation alleviates Mn-induced neurotoxicity, which is indicative of the significant role of gut microflora in the cascade of Mn-mediated neurotoxicity. High doses of Mn may cause enterocyte toxicity and affect gut wall integrity through disruption of tight junctions. The resulting increase in gut wall permeability further promotes increased translocation of LPS and neuroactive bacterial metabolites to the systemic blood flow, ultimately gaining access to the brain and leading to neuroinflammation and neurotransmitter imbalance. Therefore, the existing data lead us to hypothesize that gut microbiota should be considered as a potential target of Mn toxicity, although more detailed studies are required to characterize the interplay between Mn exposure and the gut, as well as its role in the pathogenesis of neurodegeneration and other diseases.
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Affiliation(s)
- Alexey A. Tinkov
- Laboratory of Ecobiomonitoring and Quality Control, Yaroslavl State University, 150003 Yaroslavl, Russia;
- Laboratory of Molecular Dietetics, IM Sechenov First Moscow State Medical University (Sechenov University), 119435 Moscow, Russia;
| | - Airton C. Martins
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA;
| | - Daiana Silva Avila
- Laboratory of Biochemistry and Toxicoology in Caenorhabditis elegans, Universidade Federal do Pampa, Campus Uruguaiana, BR-472 Km 592, Uruguaiana 97500-970, RS, Brazil;
| | - Victor A. Gritsenko
- Institute of Cellular and Intracellular Symbiosis, Ural Branch of the Russian Academy of Sciences, Pionerskaya st 11, 460000 Orenburg, Russia;
| | - Anatoly V. Skalny
- Laboratory of Molecular Dietetics, IM Sechenov First Moscow State Medical University (Sechenov University), 119435 Moscow, Russia;
- Laboratory of Medical Elementology, KG Razumovsky Moscow State University of Technologies and Management, 109004 Moscow, Russia
| | - Abel Santamaria
- Laboratorio de Aminoácidos Excitadores, Instituto Nacional de Neurología y Neurocirugía, Mexico City 14269, Mexico;
| | - Eunsook Lee
- College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL 32307, USA;
| | - Aaron B. Bowman
- School of Health Sciences, Purdue University, West Lafayette, IN 47907, USA;
| | - Michael Aschner
- Laboratory of Molecular Dietetics, IM Sechenov First Moscow State Medical University (Sechenov University), 119435 Moscow, Russia;
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA;
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4
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Pfalzer AC, Wilcox JM, Codreanu SG, Totten M, Bichell TJV, Halbesma T, Umashanker P, Yang KL, Parmalee NL, Sherrod SD, Erikson KM, Harrison FE, McLean JA, Aschner M, Bowman AB. Huntington's disease genotype suppresses global manganese-responsive processes in pre-manifest and manifest YAC128 mice. Metallomics 2020; 12:1118-1130. [PMID: 32421118 PMCID: PMC7773276 DOI: 10.1039/d0mt00081g] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Manganese (Mn) is an essential micronutrient required for the proper function of several enzymes. Accumulating evidence demonstrates a selective decrease of bioavailable Mn in vulnerable cell types of Huntington's Disease (HD), an inherited progressive neurodegenerative disorder with no cure. Amelioration of underlying pathophysiology, such as alterations in Mn-dependent biology, may be therapeutic. We therefore sought to investigate global Mn-dependent and Mn-responsive biology following various Mn exposures in a mouse model of HD. YAC128 and wildtype (WT) littermate control mice received one of three different Mn exposure paradigms by subcutaneous injection of 50 mg kg-1 MnCl2·4(H2O) across two distinct HD disease stages. "Pre-manifest" (12-week old mice) mice received either a single (1 injection) or week-long (3 injections) exposure of Mn or vehicle (H2O) and were sacrificed at the pre-manifest stage. "Manifest" (32-week old) mice were sacrificed following either a week-long Mn or vehicle exposure during the manifest stage, or a 20-week-long chronic (2× weekly injections) exposure that began in the pre-manifest stage. Tissue Mn, mRNA, protein, and metabolites were measured in the striatum, the brain region most sensitive to neurodegeneration in HD. Across all Mn exposure paradigms, pre-manifest YAC128 mice exhibited a suppressed response to transcriptional and protein changes and manifest YAC128 mice showed a suppressed metabolic response, despite equivalent elevations in whole striatal Mn. We conclude that YAC128 mice respond differentially to Mn compared to WT as measured by global transcriptional, translational, and metabolomic changes, suggesting an impairment in Mn homeostasis across two different disease stages in YAC128 mice.
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Affiliation(s)
- Anna C Pfalzer
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jordyn M Wilcox
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA and Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, TN, USA and Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA
| | - Simona G Codreanu
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA and Center for Innovative Technology, Vanderbilt University, Nashville, TN, USA
| | - Melissa Totten
- Department of Nutrition, University of North Carolina-Greensboro, Greensboro, NC, USA
| | - Terry J V Bichell
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Timothy Halbesma
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Preethi Umashanker
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Kevin L Yang
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Nancy L Parmalee
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Stacy D Sherrod
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA and Center for Innovative Technology, Vanderbilt University, Nashville, TN, USA
| | - Keith M Erikson
- Department of Nutrition, University of North Carolina-Greensboro, Greensboro, NC, USA
| | - Fiona E Harrison
- Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, TN, USA and Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA and Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA
| | - John A McLean
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA and Center for Innovative Technology, Vanderbilt University, Nashville, TN, USA
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Aaron B Bowman
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA and School of Health Sciences, Purdue University, 550 Stadium Mall Drive - HAMP 1173A, West Lafayette, IN 47907-2051, USA.
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5
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Soares ATG, da Silva AC, Tinkov AA, Khan H, Santamaría A, Skalnaya MG, Skalny AV, Tsatsakis A, Bowman AB, Aschner M, Ávila DS. The impact of manganese on neurotransmitter systems. J Trace Elem Med Biol 2020; 61:126554. [PMID: 32480053 PMCID: PMC7677177 DOI: 10.1016/j.jtemb.2020.126554] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 04/09/2020] [Accepted: 05/15/2020] [Indexed: 02/07/2023]
Abstract
BACKGROUND Manganese (Mn) is a metal ubiquitously present in nature and essential for many living organisms. As a trace element, it is required in small amounts for the proper functioning of several important enzymes, and reports of Mn deficiency are indeed rare. METHODS This mini-review will cover aspects of Mn toxicokinetics and its impact on brain neurotransmission, as well as its Janus-faced effects on humans and other animal's health. RESULTS The estimated safe upper limit of intracellular Mn for physiological function is in anarrow range of 20-53 μM.Therefore, intake of higher levels of Mn and the outcomes, especially to the nervous system, have been well documented. CONCLUSION The metal affects mostly the brain by accumulating in specific areas, altering cognitive functions and locomotion, thus severely impacting the health of the exposed organisms.
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Affiliation(s)
- Ana Thalita Gonçalves Soares
- Laboratory of Biochemistry and Toxicology in Caenorhabditis elegans, Graduation Program in Biochemistry, Federal University of Pampa Campus Uruguaiana, RS, Brazil
| | - Aline Castro da Silva
- Laboratory of Biochemistry and Toxicology in Caenorhabditis elegans, Graduation Program in Biochemistry, Federal University of Pampa Campus Uruguaiana, RS, Brazil
| | - Alexey A. Tinkov
- Yaroslavl State University, Yaroslavl, Russia
- IM Sechenov First Moscow State Medical University, Moscow, Russia
- Federal Scientific Center of Biological Systems and Agrotechnologies of the Russian Academy of Sciences, 460000, Orenburg, Russia
| | - Haroon Khan
- Department of pharmacy, Abdul Wali khan University Mardan 23200, Pakistan
| | - Abel Santamaría
- Laboratorio de Aminoácidos Excitadores, Instituto Nacional de Neurología y Neurocirugía, SSA. Mexico City, Mexico
| | | | - Anatoly V. Skalny
- IM Sechenov First Moscow State Medical University, Moscow, Russia
- Federal Scientific Center of Biological Systems and Agrotechnologies of the Russian Academy of Sciences, 460000, Orenburg, Russia
| | - Aristidis Tsatsakis
- Laboratory of Toxicology, Medical School, School of Medicine, University of Crete, Heraklion 71003, Greece
| | - Aaron B. Bowman
- School of Health Sciences, Purdue University, West Lafayette, IN 47906, USA
| | - Michael Aschner
- IM Sechenov First Moscow State Medical University, Moscow, Russia
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Daiana Silva Ávila
- Laboratory of Biochemistry and Toxicology in Caenorhabditis elegans, Graduation Program in Biochemistry, Federal University of Pampa Campus Uruguaiana, RS, Brazil
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Ke T, Sidoryk-Wegrzynowicz M, Pajarillo E, Rizor A, Soares FAA, Lee E, Aschner M. Role of Astrocytes in Manganese Neurotoxicity Revisited. Neurochem Res 2019; 44:2449-2459. [PMID: 31571097 PMCID: PMC7757856 DOI: 10.1007/s11064-019-02881-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 09/13/2019] [Accepted: 09/16/2019] [Indexed: 12/17/2022]
Abstract
Manganese (Mn) overexposure is a public health concern due to its widespread industrial usage and the risk for environmental contamination. The clinical symptoms of Mn neurotoxicity, or manganism, share several pathological features of Parkinson's disease (PD). Biologically, Mn is an essential trace element, and Mn in the brain is preferentially localized in astrocytes. This review summarizes the role of astrocytes in Mn-induced neurotoxicity, specifically on the role of neurotransmitter recycling, neuroinflammation, and genetics. Mn overexposure can dysregulate astrocytic cycling of glutamine (Gln) and glutamate (Glu), which is the basis for Mn-induced excitotoxic neuronal injury. In addition, reactive astrocytes are important mediators of Mn-induced neuronal damage by potentiating neuroinflammation. Genetic studies, including those with Caenorhabditis elegans (C. elegans) have uncovered several genes associated with Mn neurotoxicity. Though we have yet to fully understand the role of astrocytes in the pathologic changes characteristic of manganism, significant strides have been made over the last two decades in deciphering the role of astrocytes in Mn-induced neurotoxicity and neurodegeneration.
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Affiliation(s)
- Tao Ke
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Marta Sidoryk-Wegrzynowicz
- Laboratory of Pathoneurochemistry, Department of Neurochemistry, Mossakowski Medical Research Centre, Polish Academy of Sciences, 5 Pawinskiego Street, 02-106, Warsaw, Poland
| | - Edward Pajarillo
- Department of Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, 32307, USA
| | - Asha Rizor
- Department of Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, 32307, USA
| | - Félix Alexandre Antunes Soares
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.,Department of Biochemistry and Molecular Biology, Federal University of Santa Maria, Santa Maria, RS, Brazil
| | - Eunsook Lee
- Department of Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, 32307, USA
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA. .,Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Forchheimer Building, Room 209, Bronx, NY, 10461, USA.
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7
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Gigliobianco MR, Di Martino P, Deng S, Casadidio C, Censi R. New Advanced Strategies for the Treatment of Lysosomal Diseases Affecting the Central Nervous System. Curr Pharm Des 2019; 25:1933-1950. [DOI: 10.2174/1381612825666190708213159] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 06/19/2019] [Indexed: 11/22/2022]
Abstract
Lysosomal Storage Disorders (LSDs), also known as lysosomal diseases (LDs) are a group of serious genetic diseases characterized by not only the accumulation of non-catabolized compounds in the lysosomes due to the deficiency of specific enzymes which usually eliminate these compounds, but also by trafficking, calcium changes and acidification. LDs mainly affect the central nervous system (CNS), which is difficult to reach for drugs and biological molecules due to the presence of the blood-brain barrier (BBB). While some therapies have proven highly effective in treating peripheral disorders in LD patients, they fail to overcome the BBB. Researchers have developed many strategies to circumvent this problem, for example, by creating carriers for enzyme delivery, which improve the enzyme’s half-life and the overexpression of receptors and transporters in the luminal or abluminal membranes of the BBB. This review aims to successfully examine the strategies developed during the last decade for the treatment of LDs, which mainly affect the CNS. Among the LD treatments, enzyme-replacement therapy (ERT) and gene therapy have proven effective, while nanoparticle, fusion protein, and small molecule-based therapies seem to offer considerable promise to treat the CNS pathology. This work also analyzed the challenges of the study to design new drug delivery systems for the effective treatment of LDs. Polymeric nanoparticles and liposomes are explored from their technological point of view and for the most relevant preclinical studies showing that they are excellent choices to protect active molecules and transport them through the BBB to target specific brain substrates for the treatment of LDs.
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Affiliation(s)
- Maria R. Gigliobianco
- School of Pharmacy, University of Camerino, Via A. D'Accoiso, 16, 62032, Camerino MC, Italy
| | - Piera Di Martino
- School of Pharmacy, University of Camerino, Via A. D'Accoiso, 16, 62032, Camerino MC, Italy
| | - Siyuan Deng
- School of Pharmacy, University of Camerino, Via A. D'Accoiso, 16, 62032, Camerino MC, Italy
| | - Cristina Casadidio
- School of Pharmacy, University of Camerino, Via A. D'Accoiso, 16, 62032, Camerino MC, Italy
| | - Roberta Censi
- School of Pharmacy, University of Camerino, Via A. D'Accoiso, 16, 62032, Camerino MC, Italy
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8
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Huat TJ, Camats-Perna J, Newcombe EA, Valmas N, Kitazawa M, Medeiros R. Metal Toxicity Links to Alzheimer's Disease and Neuroinflammation. J Mol Biol 2019; 431:1843-1868. [PMID: 30664867 DOI: 10.1016/j.jmb.2019.01.018] [Citation(s) in RCA: 239] [Impact Index Per Article: 47.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 01/10/2019] [Accepted: 01/11/2019] [Indexed: 12/11/2022]
Abstract
As the median age of the population increases, the number of individuals with Alzheimer's disease (AD) and the associated socio-economic burden are predicted to worsen. While aging and inherent genetic predisposition play major roles in the onset of AD, lifestyle, physical fitness, medical condition, and social environment have emerged as relevant disease modifiers. These environmental risk factors can play a key role in accelerating or decelerating disease onset and progression. Among known environmental risk factors, chronic exposure to various metals has become more common among the public as the aggressive pace of anthropogenic activities releases excess amount of metals into the environment. As a result, we are exposed not only to essential metals, such as iron, copper, zinc and manganese, but also to toxic metals including lead, aluminum, and cadmium, which perturb metal homeostasis at the cellular and organismal levels. Herein, we review how these metals affect brain physiology and immunity, as well as their roles in the accumulation of toxic AD proteinaceous species (i.e., β-amyloid and tau). We also discuss studies that validate the disruption of immune-related pathways as an important mechanism of toxicity by which metals can contribute to AD. Our goal is to increase the awareness of metals as players in the onset and progression of AD.
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Affiliation(s)
- Tee Jong Huat
- Neurula Laboratory, Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia; Centre for Stem Cell Ageing and Regenerative Engineering, The University of Queensland, Brisbane, Australia.
| | - Judith Camats-Perna
- Neurula Laboratory, Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Estella A Newcombe
- Neurula Laboratory, Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Nicholas Valmas
- Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Masashi Kitazawa
- Center for Occupational and Environmental Health, Department of Medicine, University of California, Irvine, CA, USA
| | - Rodrigo Medeiros
- Neurula Laboratory, Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia.
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9
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McKenna MC, Schuck PF, Ferreira GC. Fundamentals of CNS energy metabolism and alterations in lysosomal storage diseases. J Neurochem 2018; 148:590-599. [PMID: 30144055 DOI: 10.1111/jnc.14577] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 08/05/2018] [Accepted: 08/22/2018] [Indexed: 01/03/2023]
Abstract
The brain has a very high requirement for energy. Adult brain relies on glucose as an energy substrate, whereas developing brain can utilize alternative substrates as well as glucose for energy and for the biosynthesis of lipids and proteins required for brain development. Metabolism provides the energy required to support all cellular functions and brain development and building blocks for macromolecules. Lysosomes are organelles involved in breakdown of biological compounds including proteins and complex lipids in the body and brain. Recent studies suggest that lysosomal dysfunction can damage neurons and/or alter neurotransmitter homeostasis. Several studies also implicate mitochondrial dysfunction in the pathophysiology of brain damage in lysosomal storage diseases. This manuscript provides a brief review of energy metabolism and the key pathways involved in metabolism in brain. Roles of lysosomes related to metabolism and neurotransmission are discussed, and evidence for mitochondrial dysfunction in several lysosomal storage diseases is presented. This article is part of the Special Issue "Lysosomal Storage Disorders".
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Affiliation(s)
- Mary C McKenna
- Department of Pediatrics, University of Maryland School of Medicine, Baltimore, Maryland, USA.,Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Patricia F Schuck
- School of Sciences, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Gustavo C Ferreira
- Department of Pediatrics, University of Maryland School of Medicine, Baltimore, Maryland, USA.,Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro, Rio Grande do Sul, Brazil
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10
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Osipova ED, Semyachkina-Glushkovskaya OV, Morgun AV, Pisareva NV, Malinovskaya NA, Boitsova EB, Pozhilenkova EA, Belova OA, Salmin VV, Taranushenko TE, Noda M, Salmina AB. Gliotransmitters and cytokines in the control of blood-brain barrier permeability. Rev Neurosci 2018; 29:567-591. [DOI: 10.1515/revneuro-2017-0092] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 11/26/2017] [Indexed: 11/15/2022]
Abstract
AbstractThe contribution of astrocytes and microglia to the regulation of neuroplasticity or neurovascular unit (NVU) is based on the coordinated secretion of gliotransmitters and cytokines and the release and uptake of metabolites. Blood-brain barrier (BBB) integrity and angiogenesis are influenced by perivascular cells contacting with the abluminal side of brain microvessel endothelial cells (pericytes, astrocytes) or by immune cells existing (microglia) or invading the NVU (macrophages) under pathologic conditions. The release of gliotransmitters or cytokines by activated astroglial and microglial cells is provided by distinct mechanisms, affects intercellular communication, and results in the establishment of microenvironment controlling BBB permeability and neuroinflammation. Glial glutamate transporters and connexin and pannexin hemichannels working in the tight functional coupling with the purinergic system serve as promising molecular targets for manipulating the intercellular communications that control BBB permeability in brain pathologies associated with excessive angiogenesis, cerebrovascular remodeling, and BBB-mediated neuroinflammation. Substantial progress in deciphering the molecular mechanisms underlying the (patho)physiology of perivascular glia provides promising approaches to novel clinically relevant therapies for brain disorders. The present review summarizes the current understandings on the secretory machinery expressed in glial cells (glutamate transporters, connexin and pannexin hemichannels, exocytosis mechanisms, membrane-derived microvesicles, and inflammasomes) and the role of secreted gliotransmitters and cytokines in the regulation of NVU and BBB permeability in (patho)physiologic conditions.
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11
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de Moura TC, Afadlal S, Hazell AS. Potential for stem cell treatment in manganism. Neurochem Int 2018; 112:134-145. [DOI: 10.1016/j.neuint.2017.10.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 09/06/2017] [Accepted: 10/09/2017] [Indexed: 02/08/2023]
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12
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Lei L, Huang M, Su L, Xie D, Mamuya FA, Ham O, Tsuji K, Păunescu TG, Yang B, Lu HAJ. Manganese promotes intracellular accumulation of AQP2 via modulating F-actin polymerization and reduces urinary concentration in mice. Am J Physiol Renal Physiol 2017; 314:F306-F316. [PMID: 29046300 DOI: 10.1152/ajprenal.00391.2017] [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] [Indexed: 12/20/2022] Open
Abstract
Aquaporin-2 (AQP2) is a water channel protein expressed in principal cells (PCs) of the kidney collecting ducts (CDs) and plays a critical role in mediating water reabsorption and urine concentration. AQP2 undergoes both regulated trafficking mediated by vasopressin (VP) and constitutive recycling, which is independent of VP. For both pathways, actin cytoskeletal dynamics is a key determinant of AQP2 trafficking. We report here that manganese chloride (MnCl2) is a novel and potent regulator of AQP2 trafficking in cultured cells and in the kidney. MnCl2 treatment promoted internalization and intracellular accumulation of AQP2. The effect of MnCl2 on the intracellular accumulation of AQP2 was associated with activation of RhoA and actin polymerization without modification of AQP2 phosphorylation. Although the level of total and phosphorylated AQP2 did not change, MnCl2 treatment impeded VP-induced phosphorylation of AQP2 at its serine-256, -264, and -269 residues and dephosphorylation at serine 261. In addition, MnCl2 significantly promoted F-actin polymerization along with downregulation of RhoA activity and prevented VP-induced membrane accumulation of AQP2. Finally, MnCl2 treatment in mice resulted in significant polyuria and reduced urinary concentration, likely due to intracellular relocation of AQP2 in the PCs of kidney CDs. More importantly, the reduced urinary concentration caused by MnCl2 treatment in animals was not corrected by VP. In summary, our study identified a novel effect of MnCl2 on AQP2 trafficking through modifying RhoA activity and actin polymerization and uncovered its potent impact on water diuresis in vivo.
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Affiliation(s)
- Lei Lei
- Department of Pharmacology, School of Basic Medical Sciences, Peking University , Beijing , People's Republic of China.,Program in Membrane Biology, Center for Systems Biology, and Division of Nephrology, Department of Medicine, Massachusetts General Hospital , Boston, Massachusetts
| | - Ming Huang
- Department of Pharmacology, School of Basic Medical Sciences, Peking University , Beijing , People's Republic of China.,Program in Membrane Biology, Center for Systems Biology, and Division of Nephrology, Department of Medicine, Massachusetts General Hospital , Boston, Massachusetts
| | - Limin Su
- Department of Pharmacology, School of Basic Medical Sciences, Peking University , Beijing , People's Republic of China.,Program in Membrane Biology, Center for Systems Biology, and Division of Nephrology, Department of Medicine, Massachusetts General Hospital , Boston, Massachusetts
| | - Dongping Xie
- Program in Membrane Biology, Center for Systems Biology, and Division of Nephrology, Department of Medicine, Massachusetts General Hospital , Boston, Massachusetts
| | - Fahmy A Mamuya
- Program in Membrane Biology, Center for Systems Biology, and Division of Nephrology, Department of Medicine, Massachusetts General Hospital , Boston, Massachusetts.,Harvard Medical School , Boston, Massachusetts
| | - Onju Ham
- Program in Membrane Biology, Center for Systems Biology, and Division of Nephrology, Department of Medicine, Massachusetts General Hospital , Boston, Massachusetts.,Harvard Medical School , Boston, Massachusetts
| | - Kenji Tsuji
- Program in Membrane Biology, Center for Systems Biology, and Division of Nephrology, Department of Medicine, Massachusetts General Hospital , Boston, Massachusetts.,Harvard Medical School , Boston, Massachusetts
| | - Teodor G Păunescu
- Program in Membrane Biology, Center for Systems Biology, and Division of Nephrology, Department of Medicine, Massachusetts General Hospital , Boston, Massachusetts.,Harvard Medical School , Boston, Massachusetts
| | - Baoxue Yang
- Department of Pharmacology, School of Basic Medical Sciences, Peking University , Beijing , People's Republic of China
| | - Hua A Jenny Lu
- Program in Membrane Biology, Center for Systems Biology, and Division of Nephrology, Department of Medicine, Massachusetts General Hospital , Boston, Massachusetts.,Harvard Medical School , Boston, Massachusetts
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13
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Sonic hedgehog induces GLT-1 degradation via PKC delta to suppress its transporter activities. Neuroscience 2017; 365:217-225. [PMID: 28993237 DOI: 10.1016/j.neuroscience.2017.09.051] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 09/25/2017] [Accepted: 09/26/2017] [Indexed: 01/20/2023]
Abstract
GLT-1 is mainly expressed in astrocytes and has a crucial role in glutamate uptake. Sonic hedgehog (SHH) can inhibit glutamate uptake and its pathway is activated in many brain diseases related with glutamate excitotoxicity. However, whether SHH regulates GLT-1 to affect glutamate uptake is not clear. Here, we use pharmacological and genetic methods to show that SHH induces GLT-1 degradation in astrocytes in a manner that is dependent on PKC delta (PKCδ) to regulate GLT-1 activities. GLT-1 protein levels are reduced as early as 2 hs in astrocytes after incubation with SHH, whereas its mRNA levels are not changed. This reduction is recapitulated when astrocytes are transfected with SmoA1, a constitutively active form of Smoothened (Smo), the mediator of SHH pathway. The reduction of GLT-1 and inhibition of aspartate current are not observed when staurosporine (STP) and BisindolylmaleimideII (BisII), agents known as PKC inhibitors, are present. Further, when PKCδ is knocked down in astrocytes, SHH cannot reduce GLT-1 protein levels. Therefore, SHH induces degradation of GLT-1 through PKCδ to regulate its activities.
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Abstract
Manganese (Mn) is an essential trace element, serving as a cofactor for several enzymes involved in various cellular and biochemical reactions in human body. However, chronic overexposure to Mn from occupational or environmental sources induces a neurological disorder, characterized by psychiatric, cognitive, and motor abnormalities, referred to as manganism. Mn-induced neurotoxicity is known to target astrocytes since these cells preferentially accumulate Mn. Astrocytes are the most abundant non-neuronal glial cells in the brain, and they play a critical role in maintaining the optimal glutamate levels to prevent excitotoxic death. The fine regulation of glutamate in the brain is accomplished by two major glutamate transporters - glutamate transporter-1 (GLT-1) and glutamate aspartate transporter (GLAST) that are predominantly expressed in astrocytes. Excitotoxic neuronal injury has been demonstrated as a critical mechanism involved in Mn neurotoxicity and implicated in the pathological signs of multiple neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Recent evidences also establish that Mn directly deregulates the expression and function of both astrocytic glutamate transporters by decreasing mRNA and protein levels of GLT-1 and GLAST. Herein, we will review the mechanisms of Mn-induced gene regulation of glutamate transporters at the transcriptional level and their role in Mn toxicity.
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15
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Shallcross L, Ritchie S, Harberts E, Tammaro A, Gaitens J, Gaspari AA. Manganese oxidation state as a cause of irritant patch test reactions. Dermatitis 2014; 25:66-71. [PMID: 24603521 DOI: 10.1097/der.0000000000000032] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Manganese chloride (MnCl2) 2.5% is included in the extended metals patch test series to evaluate patients for contact hypersensitivity to this metal salt. OBJECTIVES The objective of this study was to prospectively determine the rate of allergic and irritant patch test reactions to MnCl2 (Mn(II)), Mn2O3 (Mn(III)), and KMnO4 (Mn(VII)) in a cohort of patients undergoing patch testing. METHODS Fifty-eight patients were patch tested with MnCl2, Mn2O3, and KMnO4, each at 2.5% in petrolatum. Patch readings were taken at 48, and 72 or 96 hours, and scored using standard methods. Cultured monolayers of keratinocytes (KCs) were exposed to MnCl2, Mn2O3, and KMnO4 in aqueous culture medium, and cell survival and cytokine release were studied. CONCLUSIONS MnCl2 caused irritant patch test reactions in 41% of the cohort, whereas Mn2O3 and KMnO4 caused a significantly lower rate of irritant reactions (both 3%). No allergic morphologies were observed. Similarly, in cultured KC monolayers, only MnCl2 was cytotoxic to KC and induced tumor necrosis factor α release.The oxidation state of manganese used for patch testing affects the irritancy of this metal salt, as Mn(II) caused an unacceptably high rate of irritant reactions in a cohort of patients. In vitro studies confirmed these clinical data, as only Mn(II) was cytotoxic to cultured monolayers of KC.
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Affiliation(s)
- Laurie Shallcross
- From the Departments of *Dermatology and †Microbiology/Immunology, University of Maryland School of Medicine, Baltimore MD; ‡Department of Dermatology, La Sapienza University, Rome, Italy; and §Department of Medicine, University of Maryland School of Medicine, Baltimore MD
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16
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Karki P, Smith K, Johnson J, Aschner M, Lee E. Role of transcription factor yin yang 1 in manganese-induced reduction of astrocytic glutamate transporters: Putative mechanism for manganese-induced neurotoxicity. Neurochem Int 2014; 88:53-9. [PMID: 25128239 DOI: 10.1016/j.neuint.2014.08.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 07/31/2014] [Accepted: 08/05/2014] [Indexed: 10/24/2022]
Abstract
Astrocytes are the most abundant non-neuronal glial cells in the brain. Once relegated to a mere supportive role for neurons, contemporary dogmas ascribe multiple active roles for these cells in central nervous system (CNS) function, including maintenance of optimal glutamate levels in synapses. Regulation of glutamate levels in the synaptic cleft is crucial for preventing excitotoxic neuronal injury. Glutamate levels are regulated predominantly by two astrocytic glutamate transporters, glutamate transporter 1 (GLT-1) and glutamate aspartate transporter (GLAST). Indeed, the dysregulation of these transporters has been linked to several neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD) and Parkinson's disease (PD), as well as manganism, which is caused by overexposure to the trace metal, manganese (Mn). Although Mn is an essential trace element, its excessive accumulation in the brain as a result of chronic occupational or environmental exposures induces a neurological disorder referred to as manganism, which shares common pathological features with Parkinsonism. Mn decreases the expression and function of both GLAST and GLT-1. Astrocytes are commonly targeted by Mn, and thus reduction in astrocytic glutamate transporter function represents a critical mechanism of Mn-induced neurotoxicity. In this review, we will discuss the role of astrocytic glutamate transporters in neurodegenerative diseases and Mn-induced neurotoxicity.
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Affiliation(s)
- Pratap Karki
- Department of Physiology, Meharry Medical College, Nashville, TN 37208, United States
| | - Keisha Smith
- Department of Physiology, Meharry Medical College, Nashville, TN 37208, United States
| | - James Johnson
- Department of Physiology, Meharry Medical College, Nashville, TN 37208, United States
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, United States
| | - Eunsook Lee
- Department of Physiology, Meharry Medical College, Nashville, TN 37208, United States.
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17
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Shan D, Mount D, Moore S, Haroutunian V, Meador-Woodruff JH, McCullumsmith RE. Abnormal partitioning of hexokinase 1 suggests disruption of a glutamate transport protein complex in schizophrenia. Schizophr Res 2014; 154:1-13. [PMID: 24560881 PMCID: PMC4151500 DOI: 10.1016/j.schres.2014.01.028] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 01/13/2014] [Accepted: 01/17/2014] [Indexed: 02/08/2023]
Abstract
Excitatory amino acid transporter 2 (EAAT2) belongs to a family of Na(+) dependent glutamate transporters that maintain a low synaptic concentration of glutamate by removing glutamate from the synaptic cleft into astroglia and neurons. EAAT2 activity depends on Na(+) and K(+) gradients generated by Na(+)/K(+) ATPase and ATP. Hexokinase 1 (HK1), an initial enzyme of glycolysis, binds to mitochondrial outer membrane where it couples cytosolic glycolysis to mitochondrial oxidative phosphorylation, producing ATP utilized by the EAAT2/Na(+)/K(+) ATPase protein complex to facilitate glutamate reuptake. In this study, we hypothesized that the protein complex formed by EAAT2, Na(+)/K(+) ATPase and mitochondrial proteins in human postmortem prefrontal cortex may be disrupted, leading to abnormal glutamate transmission in schizophrenia. We first determined that EAAT2, Na(+)/K(+) ATPase, HK1 and aconitase were found in both EAAT2 and Na(+)/K(+) ATPase interactomes by immunoisolation and mass spectrometry in human postmortem prefrontal cortex. Next, we measured levels of glutamate transport complex proteins in subcellular fractions in the dorsolateral prefrontal cortex and found increases in the EAAT2B isoform of EAAT2 in a fraction containing extrasynaptic membranes and increased aconitase 1 in a mitochondrial fraction. Finally, an increased ratio of HK1 protein in the extrasynaptic membrane/mitochondrial fraction was found in subjects with schizophrenia, suggesting that HK1 protein is abnormally partitioned in this illness. Our findings indicate that the integrity of the glutamate transport protein complex may be disrupted, leading to decreased perisynaptic buffering and reuptake of glutamate, as well as impaired energy metabolism in schizophrenia.
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Affiliation(s)
- Dan Shan
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Daniel Mount
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Stephen Moore
- Department of Science and Engineering Complex, University of Alabama, Tuscaloosa, AL, USA
| | | | - James H. Meador-Woodruff
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, USA,Evelyn F. McKnight Brain Institute, Birmingham, AL, USA
| | - Robert E. McCullumsmith
- Department of Psychiatry, University of Cincinnati, Cincinnati, OH, USA,Corresponding author at: Department of Psychiatry, 231 Albert Sabin Way, ML 0583, Suite E688, Cincinnati, OH 45267-0583, USA
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18
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da Silva Santos V, Bisen-Hersh E, Yu Y, Cabral ISR, Nardini V, Culbreth M, Teixeira da Rocha JB, Barbosa F, Aschner M. Anthocyanin-rich açaí (Euterpe oleracea Mart.) extract attenuates manganese-induced oxidative stress in rat primary astrocyte cultures. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2014; 77:390-404. [PMID: 24617543 DOI: 10.1080/15287394.2014.880392] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Manganese (Mn) is an essential element for human health. However, at high concentrations Mn may be neurotoxic. Mn accumulates in astrocytes, affecting their redox status. In view of the high antioxidant and anti-inflammatory properties of the exotic Brazilian fruit açaí (Euterpe oleracea Mart.), its methanolic extract was obtained by solid-phase extraction (SPE). This açaí extract showed considerable anthocyanins content and direct antioxidant capacity. The açaí extract scavenged 2,2-diphenyl-1-picrylhydrazyl radicals (DPPH•) with an EC₅₀ of 19.1 ppm, showing higher antioxidant activity compared to butylated hydroxytoluene (BHT), but lower than ascorbic acid and quercetin. This obtained açaí extract also attenuated Mn-induced oxidative stress in primary cultured astrocytes. Specifically, the açaí extract at an optimal and nutritionally relevant concentration of 0.1 μg/ml prevented Mn-induced oxidative stress by (1) restoring GSH/GSSG ratio and net glutamate uptake, (2) protecting astrocytic membranes from lipid peroxidation, and (3) decreasing Mn-induced expression of erythroid 2-related factor (Nrf2) protein. A larger quantity of açaí extract exacerbated the effects of Mn on these parameters except with respect to lipid peroxidation assessed by means of F₂-isoprostanes. These studies indicate that at nutritionally relevant concentration, anthocyanins obtained from açaí protect astrocytes against Mn neurotoxicity, but at high concentrations, the "pro-oxidant" effects of its constituents likely prevail. Future studies may be profitably directed at potential protective effects of açaí anthocyanins in nutraceutical formulations.
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Affiliation(s)
- Vivian da Silva Santos
- a Department of Pediatrics , Vanderbilt University Medical Center , Nashville , Tennessee , USA
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Sidoryk-Wegrzynowicz M, Aschner M. Manganese toxicity in the central nervous system: the glutamine/glutamate-γ-aminobutyric acid cycle. J Intern Med 2013; 273:466-77. [PMID: 23360507 PMCID: PMC3633698 DOI: 10.1111/joim.12040] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Manganese (Mn) is an essential trace element that is required for maintaining proper function and regulation of numerous biochemical and cellular reactions. Despite its essentiality, at excessive levels Mn is toxic to the central nervous system (CNS). Increased accumulation of Mn in specific brain regions, such as the substantia nigra, globus pallidus and striatum, triggers neurotoxicity resulting in a neurological brain disorder, termed manganism. Mn has been also implicated in the pathophysiology of several other neurodegenerative diseases. Its toxicity is associated with disruption of the glutamine (Gln)/glutamate (Glu)-γ-aminobutyric acid (GABA) cycle (GGC) between astrocytes and neurons, thus leading to changes in Glu-ergic and/or GABAergic transmission and Gln metabolism. Here we discuss the common mechanisms underlying Mn-induced neurotoxicity and their relationship to CNS pathology and GGC impairment.
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20
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Sidoryk-Wegrzynowicz M, Aschner M. Role of astrocytes in manganese mediated neurotoxicity. BMC Pharmacol Toxicol 2013; 14:23. [PMID: 23594835 PMCID: PMC3637816 DOI: 10.1186/2050-6511-14-23] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 04/10/2013] [Indexed: 01/08/2023] Open
Abstract
Astrocytes are responsible for numerous aspects of metabolic support, nutrition, control of the ion and neurotransmitter environment in central nervous system (CNS). Failure by astrocytes to support essential neuronal metabolic requirements plays a fundamental role in the pathogenesis of brain injury and the ensuing neuronal death. Astrocyte-neuron interactions play a central role in brain homeostasis, in particular via neurotransmitter recycling functions. Disruption of the glutamine (Gln)/glutamate (Glu) -γ-aminobutyric acid (GABA) cycle (GGC) between astrocytes and neurons contributes to changes in Glu-ergic and/or GABA-ergic transmission, and is associated with several neuropathological conditions, including manganese (Mn) toxicity. In this review, we discuss recent advances in support of the important roles for astrocytes in normal as well as neuropathological conditions primarily those caused by exposure to Mn.
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Farina M, Avila DS, da Rocha JBT, Aschner M. Metals, oxidative stress and neurodegeneration: a focus on iron, manganese and mercury. Neurochem Int 2012; 62:575-94. [PMID: 23266600 DOI: 10.1016/j.neuint.2012.12.006] [Citation(s) in RCA: 357] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2012] [Revised: 12/07/2012] [Accepted: 12/10/2012] [Indexed: 02/08/2023]
Abstract
Essential metals are crucial for the maintenance of cell homeostasis. Among the 23 elements that have known physiological functions in humans, 12 are metals, including iron (Fe) and manganese (Mn). Nevertheless, excessive exposure to these metals may lead to pathological conditions, including neurodegeneration. Similarly, exposure to metals that do not have known biological functions, such as mercury (Hg), also present great health concerns. This review focuses on the neurodegenerative mechanisms and effects of Fe, Mn and Hg. Oxidative stress (OS), particularly in mitochondria, is a common feature of Fe, Mn and Hg toxicity. However, the primary molecular targets triggering OS are distinct. Free cationic iron is a potent pro-oxidant and can initiate a set of reactions that form extremely reactive products, such as OH. Mn can oxidize dopamine (DA), generating reactive species and also affect mitochondrial function, leading to accumulation of metabolites and culminating with OS. Cationic Hg forms have strong affinity for nucleophiles, such as -SH and -SeH. Therefore, they target critical thiol- and selenol-molecules with antioxidant properties. Finally, we address the main sources of exposure to these metals, their transport mechanisms into the brain, and therapeutic modalities to mitigate their neurotoxic effects.
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Affiliation(s)
- Marcelo Farina
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC, Brazil
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