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Air Pollution-Related Brain Metal Dyshomeostasis as a Potential Risk Factor for Neurodevelopmental Disorders and Neurodegenerative Diseases. ATMOSPHERE 2020. [DOI: 10.3390/atmos11101098] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Increasing evidence links air pollution (AP) exposure to effects on the central nervous system structure and function. Particulate matter AP, especially the ultrafine (nanoparticle) components, can carry numerous metal and trace element contaminants that can reach the brain in utero and after birth. Excess brain exposure to either essential or non-essential elements can result in brain dyshomeostasis, which has been implicated in both neurodevelopmental disorders (NDDs; autism spectrum disorder, schizophrenia, and attention deficit hyperactivity disorder) and neurodegenerative diseases (NDGDs; Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and amyotrophic lateral sclerosis). This review summarizes the current understanding of the extent to which the inhalational or intranasal instillation of metals reproduces in vivo the shared features of NDDs and NDGDs, including enlarged lateral ventricles, alterations in myelination, glutamatergic dysfunction, neuronal cell death, inflammation, microglial activation, oxidative stress, mitochondrial dysfunction, altered social behaviors, cognitive dysfunction, and impulsivity. Although evidence is limited to date, neuronal cell death, oxidative stress, and mitochondrial dysfunction are reproduced by numerous metals. Understanding the specific contribution of metals/trace elements to this neurotoxicity can guide the development of more realistic animal exposure models of human AP exposure and consequently lead to a more meaningful approach to mechanistic studies, potential intervention strategies, and regulatory requirements.
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Werner S, Nies E. Olfactory dysfunction revisited: a reappraisal of work-related olfactory dysfunction caused by chemicals. J Occup Med Toxicol 2018. [PMID: 30202422 DOI: 10.1186/s12995‐018‐0209‐6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Occupational exposure to numerous individual chemicals has been associated with olfactory dysfunction, mainly in individual case descriptions. Comprehensive epidemiological investigations into the olfactotoxic effect of working substances show that the human sense of smell may be impaired by exposure to metal compounds involving cadmium, chromium and nickel, and to formaldehyde. This conclusion is supported by the results of animal experiments. The level of evidence for a relationship between olfactory dysfunction and workplace exposure to other substances is relatively weak.
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Affiliation(s)
- Sabine Werner
- Institute for Occupational Safety and Health of the German Social Accident Insurance, Unit Toxicology of Industrial Chemicals, Alte Heerstrasse 111, 53757 Sankt Augustin, Germany
| | - Eberhard Nies
- Institute for Occupational Safety and Health of the German Social Accident Insurance, Unit Toxicology of Industrial Chemicals, Alte Heerstrasse 111, 53757 Sankt Augustin, Germany
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Werner S, Nies E. Olfactory dysfunction revisited: a reappraisal of work-related olfactory dysfunction caused by chemicals. J Occup Med Toxicol 2018; 13:28. [PMID: 30202422 PMCID: PMC6124006 DOI: 10.1186/s12995-018-0209-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 07/30/2018] [Indexed: 11/10/2022] Open
Abstract
Occupational exposure to numerous individual chemicals has been associated with olfactory dysfunction, mainly in individual case descriptions. Comprehensive epidemiological investigations into the olfactotoxic effect of working substances show that the human sense of smell may be impaired by exposure to metal compounds involving cadmium, chromium and nickel, and to formaldehyde. This conclusion is supported by the results of animal experiments. The level of evidence for a relationship between olfactory dysfunction and workplace exposure to other substances is relatively weak.
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Affiliation(s)
- Sabine Werner
- Institute for Occupational Safety and Health of the German Social Accident Insurance, Unit Toxicology of Industrial Chemicals, Alte Heerstrasse 111, 53757 Sankt Augustin, Germany
| | - Eberhard Nies
- Institute for Occupational Safety and Health of the German Social Accident Insurance, Unit Toxicology of Industrial Chemicals, Alte Heerstrasse 111, 53757 Sankt Augustin, Germany
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Foster ML, Rao DB, Francher T, Traver S, Dorman DC. Olfactory toxicity in rats following manganese chloride nasal instillation: A pilot study. Neurotoxicology 2017; 64:284-290. [PMID: 28917718 DOI: 10.1016/j.neuro.2017.09.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 09/08/2017] [Accepted: 09/11/2017] [Indexed: 12/27/2022]
Abstract
Following inhalation, manganese travels along the olfactory nerve from the olfactory epithelium (OE) to the olfactory bulb (OB). Occupational exposure to inhaled manganese is associated with changes in olfactory function. This pilot study evaluated two related hypotheses: (a) intranasal manganese administration increases OE and OB manganese concentrations; and (b) intranasal manganese exposure impairs performance of previously trained rats on a go-no-go olfactory discrimination (OD) task. Male Fischer 344 rats were trained to either lever press ("go") in response to a positive conditioned stimulus (CS+: vanillin) or to do nothing ("no go") when a negative conditioned stimulus (CS-: amyl acetate) was present. Following odor training, rats were randomly assigned to either a manganese (200mM MnCl2) or 0.9% saline treatment group (n=4-5 rats/group). Administration of either saline or manganese was performed on isoflurane-anesthetized rats as 40μL bilateral intranasal instillations. Rats were retested 48h later using the vanillin/amyl acetate OD task, then euthanized, followed by collection of the OE and OB. Manganese concentrations in tissue samples were analyzed by ICP-MS. An additional cohort of rats (n=3-4/group) was instilled similarly with saline or manganese and nasal and OB pathology assessed 48h later. Manganese-exposed rats had increased manganese levels in both the OE and OB and decreased performance in the OD task when compared with control animals. Histopathological evaluation of the caudal nasal cavity showed moderate, acute to subacute suppurative inflammation of the olfactory epithelium and submucosa of the ethmoid turbinates and mild suppurative exudate in the nasal sinuses in animals given manganese. No histologic changes were evident in the OB. The nasal instillation and OD procedures developed in this study are useful methods to assess manganese - induced olfactory deficits.
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Affiliation(s)
- Melanie L Foster
- College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Deepa B Rao
- Division of Psychiatry Products, Center for Drug Evaluation and Research, Food and Drug Administration, USA.
| | - Taylor Francher
- College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Samantha Traver
- College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - David C Dorman
- College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA.
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Ajmani GS, Suh HH, Pinto JM. Effects of Ambient Air Pollution Exposure on Olfaction: A Review. ENVIRONMENTAL HEALTH PERSPECTIVES 2016; 124:1683-1693. [PMID: 27285588 PMCID: PMC5089874 DOI: 10.1289/ehp136] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 02/25/2016] [Accepted: 05/20/2016] [Indexed: 05/03/2023]
Abstract
BACKGROUND Olfactory dysfunction affects millions of people worldwide. This sensory impairment is associated with neurodegenerative disease and significantly decreased quality of life. Exposure to airborne pollutants has been implicated in olfactory decline, likely due to the anatomic susceptibility of the olfactory nerve to the environment. Historically, studies have focused on occupational exposures, but more recent studies have considered effects from exposure to ambient air pollutants. OBJECTIVES To examine all relevant human data evaluating a link between ambient pollution exposure and olfaction and to review supporting animal data in order to examine potential mechanisms for pollution-associated olfactory loss. METHODS We identified and reviewed relevant articles from 1950 to 2015 using PubMed and Web of Science and focusing on human epidemiologic and pathophysiologic studies. Animal studies were included only to support pertinent data on humans. We reviewed findings from these studies evaluating a relationship between environmental pollutant exposure and olfactory function. RESULTS We identified and reviewed 17 articles, with 1 additional article added from a bibliography search, for a total of 18 human studies. There is evidence in human epidemiologic and pathologic studies that increased exposure to ambient air pollutants is associated with olfactory dysfunction. However, most studies have used proxies for pollution exposure in small samples of convenience. Human pathologic studies, with supporting animal work, have also shown that air pollution can contact the olfactory epithelium, translocate to the olfactory bulb, and migrate to the olfactory cortex. Pollutants can deposit at each location, causing direct damage and disruption of tissue morphology or inducing local inflammation and cellular stress responses. CONCLUSIONS Ambient air pollution may impact human olfactory function. Additional studies are needed to examine air pollution-related olfactory impacts on the general population using measured pollution exposures and to link pollution exposure with olfactory dysfunction and related pathology. Citation: Ajmani GS, Suh HH, Pinto JM. 2016. Effects of ambient air pollution exposure on olfaction: a review. Environ Health Perspect 124:1683-1693; http://dx.doi.org/10.1289/EHP136.
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Affiliation(s)
- Gaurav S. Ajmani
- Pritzker School of Medicine, University of Chicago, Chicago, Illinois, USA
| | - Helen H. Suh
- Department of Health Sciences, Northeastern University, Boston, Massachusetts, USA
| | - Jayant M. Pinto
- Section of Otolaryngology-Head and Neck Surgery, Department of Surgery, University of Chicago, Chicago, Illinois, USA
- Address correspondence to J.M. Pinto, Section of Otolaryngology-Head and Neck Surgery, Department of Surgery, The University of Chicago Medicine and Biological Sciences, MC103, 5841 South Maryland Ave., Chicago, IL 60647 USA. Telephone: (773) 702-6727. E-mail:
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Peres TV, Eyng H, Lopes SC, Colle D, Gonçalves FM, Venske DKR, Lopes MW, Ben J, Bornhorst J, Schwerdtle T, Aschner M, Farina M, Prediger RD, Leal RB. Developmental exposure to manganese induces lasting motor and cognitive impairment in rats. Neurotoxicology 2015. [PMID: 26215118 DOI: 10.1016/j.neuro.2015.07.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Exposure to high manganese (Mn) levels may damage the basal ganglia, leading to a syndrome analogous to Parkinson's disease, with motor and cognitive impairments. The molecular mechanisms underlying Mn neurotoxicity, particularly during development, still deserve further investigation. Herein, we addressed whether early-life Mn exposure affects motor coordination and cognitive function in adulthood and potential underlying mechanisms. Male Wistar rats were exposed intraperitoneally to saline (control) or MnCl2 (5, 10 or 20 mg/kg/day) from post-natal day (PND) 8-12. Behavioral tests were performed on PND 60-65 and biochemical analysis in the striatum and hippocampus were performed on PND14 or PND70. Rats exposed to Mn (10 and 20 mg/kg) performed significantly worse on the rotarod test than controls indicating motor coordination and balance impairments. The object and social recognition tasks were used to evaluate short-term memory. Rats exposed to the highest Mn dose failed to recognize a familiar object when replaced by a novel object as well as to recognize a familiar juvenile rat after a short period of time. However, Mn did not alter olfactory discrimination ability. In addition, Mn-treated rats displayed decreased levels of non-protein thiols (e.g. glutathione) and increased levels of glial fibrillary acidic protein (GFAP) in the striatum. Moreover, Mn significantly increased hippocampal glutathione peroxidase (GPx) activity. These findings demonstrate that acute low-level exposure to Mn during a critical neurodevelopmental period causes cognitive and motor dysfunctions that last into adulthood, that are accompanied by alterations in antioxidant defense system in both the hippocampus and striatum.
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Affiliation(s)
- Tanara V Peres
- Programa de Pós-graduação em Neurociências, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
| | - Helena Eyng
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Samantha C Lopes
- Departamento de Farmacologia, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Dirleise Colle
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Filipe M Gonçalves
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Débora K R Venske
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Mark W Lopes
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Juliana Ben
- Programa de Pós-graduação em Neurociências, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Julia Bornhorst
- Institute of Nutritional Sciences, University of Potsdam, Nuthetal, Germany
| | - Tanja Schwerdtle
- Institute of Nutritional Sciences, University of Potsdam, Nuthetal, Germany
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Marcelo Farina
- Programa de Pós-graduação em Neurociências, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil; Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Rui D Prediger
- Programa de Pós-graduação em Neurociências, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil; Departamento de Farmacologia, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Rodrigo B Leal
- Programa de Pós-graduação em Neurociências, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil; Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
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