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Wei W, Liu A, Liu M, Li M, Wu X, Qin C, Shan Z, Zhang L. Development of an animal model of hypothyroxinemia during pregnancy in Wistar rats. Animal Model Exp Med 2024. [PMID: 38946346 DOI: 10.1002/ame2.12459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 05/21/2024] [Indexed: 07/02/2024] Open
Abstract
BACKGROUND Hypothyroxinemia is a subclinical thyroid hormone deficiency in which the mother has inadequate levels of T4 during pregnancy. The fetus relies entirely on the mother's T4 hormone level for early neurodevelopment. Isolated maternal hypothyroxinemia (IMH) in the first trimester of pregnancy can lead to lower intelligence, lower motor scores, and a higher risk of mental illness in descendants. Here, we focus on the autism-like behavior of IMH offspring. METHODS The animals were administered 1 ppm of propylthiouracil (PTU) for 9 weeks. Then, the concentrations of T3, T4, and thyroid-stimulating hormone (TSH) were detected using enzyme-linked immunosorbent assay (ELISA) to verify the developed animal model of IMH. We performed four behavioral experiments, including the marble burying test, open-field test, three-chamber sociability test, and Morris water maze, to explore the autistic-like behavior of 40-day-old offspring rats. RESULTS The ELISA test showed that the serum T3 and TSH concentrations in the model group were normal compared with the negative control group, whereas the T4 concentration decreased. In the behavioral experiments, the number of hidden marbles in the offspring of IMH increased significantly, the frequency of entering the central compartment decreased, and the social ratio decreased significantly. CONCLUSION The animal model of IMH was developed by the administration of 1 ppm of PTU for 9 weeks, and there were autistic-like behavior changes such as anxiety, weakened social ability, and repeated stereotyping in the IMH offspring by 40 days.
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Affiliation(s)
- Wei Wei
- School of Public Health, North China University of Science and Technology, Tangshan, China
| | - Aihua Liu
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China
| | - Min Liu
- Institute of Laboratory Animal Sciences, Chinese Academy of Medical Sciences (CAMS) & Peking Union Medical College (PUMC), Beijing, China
| | - Mingfeng Li
- Institute of Laboratory Animal Sciences, Chinese Academy of Medical Sciences (CAMS) & Peking Union Medical College (PUMC), Beijing, China
| | - Xinghan Wu
- Institute of Laboratory Animal Sciences, Chinese Academy of Medical Sciences (CAMS) & Peking Union Medical College (PUMC), Beijing, China
| | - Chuan Qin
- School of Public Health, North China University of Science and Technology, Tangshan, China
- Institute of Laboratory Animal Sciences, Chinese Academy of Medical Sciences (CAMS) & Peking Union Medical College (PUMC), Beijing, China
| | - Zhongyan Shan
- Department of Endocrinology and Metabolism, NHC Key Laboratory of Diagnosis and Treatment of Thyroid Diseases, Institute of Endocrinology, The First Affiliated Hospital of China Medical University, Shenyang, China
| | - Ling Zhang
- Institute of Laboratory Animal Sciences, Chinese Academy of Medical Sciences (CAMS) & Peking Union Medical College (PUMC), Beijing, China
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Ramhøj L, Svingen T, Evrard B, Chalmel F, Axelstad M. Two thyroperoxidase-inhibiting chemicals induce shared transcriptional changes in hippocampus of developing rats. Toxicology 2024; 505:153822. [PMID: 38685447 DOI: 10.1016/j.tox.2024.153822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 04/25/2024] [Accepted: 04/26/2024] [Indexed: 05/02/2024]
Abstract
Thyroid hormone (TH) system disrupting compounds can impair brain development by perturbing TH action during critical life stages. Human exposure to TH system disrupting chemicals is therefore of great concern. To better protect humans against such chemicals, sensitive test methods that can detect effects on the developing brain are critical. Worryingly, however, current test methods are not sensitive and specific towards TH-mediated effects. To address this shortcoming, we performed RNA-sequencing of rat brains developmentally exposed to two different thyroperoxidase (TPO) inhibiting compounds, the medical drug methimazole (MMI) or the pesticide amitrole. Pregnant and lactating rats were exposed to 8 and 16 mg/kg/day(d) MMI or 25 and 50 mg/kg/d amitrole from gestational day 7 until postnatal day 16. Bulk-RNA-seq was performed on hippocampus from the 16-day old male pups. MMI and amitrole caused pronounced changes to the transcriptomes; 816 genes were differentially expressed, and 425 gene transcripts were similarly affected by both chemicals. Functional terms indicate effects from key cellular functions to changes in cell development, migration and differentiation of several cell populations. Of the total number of DEGs, 106 appeared to form a consistent transcriptional fingerprint of developmental hypothyroidism as they were similarly and dose-dependently expressed across all treatment groups. Using a filtering system, we identified 20 genes that appeared to represent the most sensitive, robust and dose-dependent markers of altered TH-mediated brain development. These markers provide inputs to the adverse outcome pathway (AOP) framework where they, in the context of linking TPO inhibiting compounds to adverse cognitive function, can be used to assess altered gene expression in the hippocampus in rat toxicity studies.
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Affiliation(s)
- Louise Ramhøj
- National Food Institute, Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark.
| | - Terje Svingen
- National Food Institute, Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark
| | - Bertrand Evrard
- Univ Rennes, Inserm, EHESP, Irset (Institut de Recherche en Santé, Environnement et Travail), UMR_S 1085, Rennes, F-35000, France
| | - Frédéric Chalmel
- Univ Rennes, Inserm, EHESP, Irset (Institut de Recherche en Santé, Environnement et Travail), UMR_S 1085, Rennes, F-35000, France
| | - Marta Axelstad
- National Food Institute, Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark
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3
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Breakell T, Kowalski I, Foerster Y, Kramer R, Erdmann M, Berking C, Heppt MV. Ultraviolet Filters: Dissecting Current Facts and Myths. J Clin Med 2024; 13:2986. [PMID: 38792526 PMCID: PMC11121922 DOI: 10.3390/jcm13102986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Revised: 05/11/2024] [Accepted: 05/16/2024] [Indexed: 05/26/2024] Open
Abstract
Skin cancer is a global and increasingly prevalent issue, causing significant individual and economic damage. UV filters in sunscreens play a major role in mitigating the risks that solar ultraviolet ra-diation poses to the human organism. While empirically effective, multiple adverse effects of these compounds are discussed in the media and in scientific research. UV filters are blamed for the dis-ruption of endocrine processes and vitamin D synthesis, damaging effects on the environment, induction of acne and neurotoxic and carcinogenic effects. Some of these allegations are based on scientific facts while others are simply arbitrary. This is especially dangerous considering the risks of exposing unprotected skin to the sun. In summary, UV filters approved by the respective governing bodies are safe for human use and their proven skin cancer-preventing properties make them in-dispensable for sensible sun protection habits. Nonetheless, compounds like octocrylene and ben-zophenone-3 that are linked to the harming of marine ecosystems could be omitted from skin care regimens in favor of the myriad of non-toxic UV filters.
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Affiliation(s)
- Thomas Breakell
- Department of Dermatology, Uniklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; (T.B.); (I.K.); (Y.F.); (R.K.); (M.E.); (C.B.)
- Comprehensive Cancer Center Erlangen-European Metropolitan Area of Nuremberg (CCC ER-EMN) and CCC Alliance WERA, 91054 Erlangen, Germany
- Bavarian Cancer Research Center (BZKF), 91052 Erlangen, Germany
| | - Isabel Kowalski
- Department of Dermatology, Uniklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; (T.B.); (I.K.); (Y.F.); (R.K.); (M.E.); (C.B.)
- Comprehensive Cancer Center Erlangen-European Metropolitan Area of Nuremberg (CCC ER-EMN) and CCC Alliance WERA, 91054 Erlangen, Germany
- Bavarian Cancer Research Center (BZKF), 91052 Erlangen, Germany
| | - Yannick Foerster
- Department of Dermatology, Uniklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; (T.B.); (I.K.); (Y.F.); (R.K.); (M.E.); (C.B.)
- Comprehensive Cancer Center Erlangen-European Metropolitan Area of Nuremberg (CCC ER-EMN) and CCC Alliance WERA, 91054 Erlangen, Germany
- Bavarian Cancer Research Center (BZKF), 91052 Erlangen, Germany
- Department of Dermatology and Allergy Biederstein, Technical University (TU) Munich, 80802 Munich, Germany
| | - Rafaela Kramer
- Department of Dermatology, Uniklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; (T.B.); (I.K.); (Y.F.); (R.K.); (M.E.); (C.B.)
- Comprehensive Cancer Center Erlangen-European Metropolitan Area of Nuremberg (CCC ER-EMN) and CCC Alliance WERA, 91054 Erlangen, Germany
- Bavarian Cancer Research Center (BZKF), 91052 Erlangen, Germany
| | - Michael Erdmann
- Department of Dermatology, Uniklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; (T.B.); (I.K.); (Y.F.); (R.K.); (M.E.); (C.B.)
- Comprehensive Cancer Center Erlangen-European Metropolitan Area of Nuremberg (CCC ER-EMN) and CCC Alliance WERA, 91054 Erlangen, Germany
- Bavarian Cancer Research Center (BZKF), 91052 Erlangen, Germany
| | - Carola Berking
- Department of Dermatology, Uniklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; (T.B.); (I.K.); (Y.F.); (R.K.); (M.E.); (C.B.)
- Comprehensive Cancer Center Erlangen-European Metropolitan Area of Nuremberg (CCC ER-EMN) and CCC Alliance WERA, 91054 Erlangen, Germany
- Bavarian Cancer Research Center (BZKF), 91052 Erlangen, Germany
| | - Markus V. Heppt
- Department of Dermatology, Uniklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; (T.B.); (I.K.); (Y.F.); (R.K.); (M.E.); (C.B.)
- Comprehensive Cancer Center Erlangen-European Metropolitan Area of Nuremberg (CCC ER-EMN) and CCC Alliance WERA, 91054 Erlangen, Germany
- Bavarian Cancer Research Center (BZKF), 91052 Erlangen, Germany
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Sabatino L, Lapi D, Del Seppia C. Factors and Mechanisms of Thyroid Hormone Activity in the Brain: Possible Role in Recovery and Protection. Biomolecules 2024; 14:198. [PMID: 38397435 PMCID: PMC10886502 DOI: 10.3390/biom14020198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 01/29/2024] [Accepted: 02/03/2024] [Indexed: 02/25/2024] Open
Abstract
Thyroid hormones (THs) are essential in normal brain development, and cognitive and emotional functions. THs act through a cascade of events including uptake by the target cells by specific cell membrane transporters, activation or inactivation by deiodinase enzymes, and interaction with nuclear thyroid hormone receptors. Several thyroid responsive genes have been described in the developing and in the adult brain and many studies have demonstrated a systemic or local reduction in TH availability in neurologic disease and after brain injury. In this review, the main factors and mechanisms associated with the THs in the normal and damaged brain will be evaluated in different regions and cellular contexts. Furthermore, the most common animal models used to study the role of THs in brain damage and cognitive impairment will be described and the use of THs as a potential recovery strategy from neuropathological conditions will be evaluated. Finally, particular attention will be given to the link observed between TH alterations and increased risk of Alzheimer's Disease (AD), the most prevalent neurodegenerative and dementing condition worldwide.
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Affiliation(s)
- Laura Sabatino
- Institute of Clinical Physiology, National Council of Research, Via Moruzzi 1, 56124 Pisa, Italy;
| | - Dominga Lapi
- Department of Biology, University of Pisa, 56127 Pisa, Italy;
| | - Cristina Del Seppia
- Institute of Clinical Physiology, National Council of Research, Via Moruzzi 1, 56124 Pisa, Italy;
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5
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Poulsen R, Zekri Y, Guyot R, Flamant F, Hansen M. Effect of in utero and lactational exposure to a thyroid hormone system disrupting chemical on mouse metabolome and brain transcriptome. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 340:122783. [PMID: 37866749 DOI: 10.1016/j.envpol.2023.122783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Revised: 10/04/2023] [Accepted: 10/18/2023] [Indexed: 10/24/2023]
Abstract
Mice were exposed to a low dose of the model thyroid hormone disruptor, propylthiouracil. Although this had only a modest effect on maternal thyroid hormones production, postnatal analysis of the pups' plasma by mass spectrometry and the brain striatum by RNA sequencing gave evidence of low lasting changes that could reflect an adverse effect on neurodevelopment. Overall, these methods proved to be sensitive enough to detect minor disruptions of thyroid hormone signalling in vivo.
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Affiliation(s)
- Rikke Poulsen
- Aarhus University, Department of Environmental Science, Frederiksborgvej 399, 4000, Roskilde, Denmark.
| | - Yanis Zekri
- Institut de Génomique Fonctionnelle de Lyon, Université Claude Bernard Lyon I, CNRS, UMR 5242, INRAE USC 1370 Ecole Normale Supérieure de Lyon 46 allée d'Italie, 69364, Lyon, France
| | - Romain Guyot
- Institut de Génomique Fonctionnelle de Lyon, Université Claude Bernard Lyon I, CNRS, UMR 5242, INRAE USC 1370 Ecole Normale Supérieure de Lyon 46 allée d'Italie, 69364, Lyon, France
| | - Frédéric Flamant
- Institut de Génomique Fonctionnelle de Lyon, Université Claude Bernard Lyon I, CNRS, UMR 5242, INRAE USC 1370 Ecole Normale Supérieure de Lyon 46 allée d'Italie, 69364, Lyon, France
| | - Martin Hansen
- Aarhus University, Department of Environmental Science, Frederiksborgvej 399, 4000, Roskilde, Denmark
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6
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Wilhelmi P, Giri V, Zickgraf FM, Haake V, Henkes S, Driemert P, Michaelis P, Busch W, Scholz S, Flick B, Barenys M, Birk B, Kamp H, Landsiedel R, Funk-Weyer D. A metabolomics approach to reveal the mechanism of developmental toxicity in zebrafish embryos exposed to 6-propyl-2-thiouracil. Chem Biol Interact 2023; 382:110565. [PMID: 37236578 DOI: 10.1016/j.cbi.2023.110565] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 05/12/2023] [Accepted: 05/23/2023] [Indexed: 05/28/2023]
Abstract
A crucial component of a substance registration and regulation is the evaluation of human prenatal developmental toxicity. Current toxicological tests are based on mammalian models, but these are costly, time consuming and may pose ethical concerns. The zebrafish embryo has evolved as a promising alternative model to study developmental toxicity. However, the implementation of the zebrafish embryotoxicity test is challenged by lacking information on the relevance of observed morphological alterations in fish for human developmental toxicity. Elucidating the mechanism of toxicity could help to overcome this limitation. Through LC-MS/MS and GC-MS metabolomics, we investigated whether changes to the endogenous metabolites can indicate pathways associated with developmental toxicity. To this aim, zebrafish embryos were exposed to different concentrations of 6-propyl-2-thiouracil (PTU), a compound known to induce developmental toxicity. The reproducibility and the concentration-dependence of the metabolome response and its association with morphological alterations were studied. Major morphological findings were reduced eye size, and other craniofacial anomalies; major metabolic changes included increased tyrosine, pipecolic acid and lysophosphatidylcholine levels, decreased methionine levels, and disturbance of the 'Phenylalanine, tyrosine and tryptophan biosynthesis' pathway. This pathway, and the changes in tyrosine and pipecolic acid levels could be linked to the mode of action of PTU, i.e., inhibition of thyroid peroxidase (TPO). The other findings suggested neurodevelopmental impairments. This proof-of-concept study demonstrated that metabolite changes in zebrafish embryos are robust and provide mechanistic information associated with the mode of action of PTU.
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Affiliation(s)
- Pia Wilhelmi
- BASF SE, Experimental Toxicology and Ecology, 67056, Ludwigshafen am Rhein, Germany; University of Barcelona, Research Group in Toxicology-GRET, 08028, Barcelona, Spain.
| | - Varun Giri
- BASF SE, Experimental Toxicology and Ecology, 67056, Ludwigshafen am Rhein, Germany.
| | | | - Volker Haake
- BASF Metabolome Solutions, 10589, Berlin, Germany
| | | | | | - Paul Michaelis
- Helmholtz Centre for Environmental Research-UFZ, Department of Bioanalytical Ecotoxicology, 04318, Leipzig, Germany
| | - Wibke Busch
- Helmholtz Centre for Environmental Research-UFZ, Department of Bioanalytical Ecotoxicology, 04318, Leipzig, Germany
| | - Stefan Scholz
- Helmholtz Centre for Environmental Research-UFZ, Department of Bioanalytical Ecotoxicology, 04318, Leipzig, Germany
| | - Burkhard Flick
- BASF SE, Experimental Toxicology and Ecology, 67056, Ludwigshafen am Rhein, Germany
| | - Marta Barenys
- University of Barcelona, Research Group in Toxicology-GRET, 08028, Barcelona, Spain; German Centre for the Protection of Laboratory Animals (Bf3R), German Federal Institute for Risk Assessment (BfR), 10589, Berlin, Germany
| | - Barbara Birk
- BASF SE, Experimental Toxicology and Ecology, 67056, Ludwigshafen am Rhein, Germany
| | | | - Robert Landsiedel
- BASF SE, Experimental Toxicology and Ecology, 67056, Ludwigshafen am Rhein, Germany; Free University of Berlin, Institute of Pharmacy, Pharmacology and Toxicology, 14195, Berlin, Germany
| | - Dorothee Funk-Weyer
- BASF SE, Experimental Toxicology and Ecology, 67056, Ludwigshafen am Rhein, Germany
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Haigis AC, Vergauwen L, LaLone CA, Villeneuve DL, O'Brien JM, Knapen D. Cross-species applicability of an adverse outcome pathway network for thyroid hormone system disruption. Toxicol Sci 2023; 195:1-27. [PMID: 37405877 DOI: 10.1093/toxsci/kfad063] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/07/2023] Open
Abstract
Thyroid hormone system disrupting compounds are considered potential threats for human and environmental health. Multiple adverse outcome pathways (AOPs) for thyroid hormone system disruption (THSD) are being developed in different taxa. Combining these AOPs results in a cross-species AOP network for THSD which may provide an evidence-based foundation for extrapolating THSD data across vertebrate species and bridging the gap between human and environmental health. This review aimed to advance the description of the taxonomic domain of applicability (tDOA) in the network to improve its utility for cross-species extrapolation. We focused on the molecular initiating events (MIEs) and adverse outcomes (AOs) and evaluated both their plausible domain of applicability (taxa they are likely applicable to) and empirical domain of applicability (where evidence for applicability to various taxa exists) in a THSD context. The evaluation showed that all MIEs in the AOP network are applicable to mammals. With some exceptions, there was evidence of structural conservation across vertebrate taxa and especially for fish and amphibians, and to a lesser extent for birds, empirical evidence was found. Current evidence supports the applicability of impaired neurodevelopment, neurosensory development (eg, vision) and reproduction across vertebrate taxa. The results of this tDOA evaluation are summarized in a conceptual AOP network that helps prioritize (parts of) AOPs for a more detailed evaluation. In conclusion, this review advances the tDOA description of an existing THSD AOP network and serves as a catalog summarizing plausible and empirical evidence on which future cross-species AOP development and tDOA assessment could build.
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Affiliation(s)
- Ann-Cathrin Haigis
- Zebrafishlab, Veterinary Physiology and Biochemistry, Department of Veterinary Sciences, University of Antwerp, 2610 Wilrijk, Belgium
| | - Lucia Vergauwen
- Zebrafishlab, Veterinary Physiology and Biochemistry, Department of Veterinary Sciences, University of Antwerp, 2610 Wilrijk, Belgium
| | - Carlie A LaLone
- Great Lakes Toxicology and Ecology Division, United States Environmental Protection Agency, Duluth, Minnesota 55804, USA
| | - Daniel L Villeneuve
- Great Lakes Toxicology and Ecology Division, United States Environmental Protection Agency, Duluth, Minnesota 55804, USA
| | - Jason M O'Brien
- Ecotoxicology and Wildlife Health Division, Environment and Climate Change Canada, Carleton University, Ottawa, Ontario K1S 5B6, Canada
| | - Dries Knapen
- Zebrafishlab, Veterinary Physiology and Biochemistry, Department of Veterinary Sciences, University of Antwerp, 2610 Wilrijk, Belgium
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Alcaide Martin A, Mayerl S. Local Thyroid Hormone Action in Brain Development. Int J Mol Sci 2023; 24:12352. [PMID: 37569727 PMCID: PMC10418487 DOI: 10.3390/ijms241512352] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 07/28/2023] [Accepted: 07/30/2023] [Indexed: 08/13/2023] Open
Abstract
Proper brain development essentially depends on the timed availability of sufficient amounts of thyroid hormone (TH). This, in turn, necessitates a tightly regulated expression of TH signaling components such as TH transporters, deiodinases, and TH receptors in a brain region- and cell-specific manner from early developmental stages onwards. Abnormal TH levels during critical stages, as well as mutations in TH signaling components that alter the global and/or local thyroidal state, result in detrimental consequences for brain development and neurological functions that involve alterations in central neurotransmitter systems. Thus, the question as to how TH signaling is implicated in the development and maturation of different neurotransmitter and neuromodulator systems has gained increasing attention. In this review, we first summarize the current knowledge on the regulation of TH signaling components during brain development. We then present recent advances in our understanding on how altered TH signaling compromises the development of cortical glutamatergic neurons, inhibitory GABAergic interneurons, cholinergic and dopaminergic neurons. Thereby, we highlight novel mechanistic insights and point out open questions in this evolving research field.
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Affiliation(s)
| | - Steffen Mayerl
- Department of Endocrinology Diabetes & Metabolism, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147 Essen, Germany
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Arts JHE, Faulhammer F, Schneider S, Salverda JGW. Investigations on learning and memory function in extended one-generation reproductive toxicity studies - when considered needed and based on what? Crit Rev Toxicol 2023; 53:372-384. [PMID: 37540214 DOI: 10.1080/10408444.2023.2236134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 06/29/2023] [Accepted: 07/07/2023] [Indexed: 08/05/2023]
Abstract
To justify investigations on learning and memory (L&M) function in extended one-generation reproductive toxicity studies (EOGRTS; Organization for Economic Co-operation and Development (OECD) test guideline (TG) 443) for registration under Registration, Evaluation, Authorization, and Restriction of Chemical (REACH), the European Chemicals Agency has referred to three publications based on which the Agency concluded that "perturbation of thyroid hormone signaling in offspring affects spatial cognitive abilities (learning and memory)" and "Therefore, it is necessary to conduct spatial learning and memory tests for F1 animals". In this paper, the inclusion of the requested L&M tests in an EOGRTS is challenged. In addition, next to the question on the validity of rodent models in general for testing thyroid hormone-dependent perturbations in brain development, the reliability of the publications specifically relied upon by the agency is questioned as these contain numerous fundamental errors in study methodology, design, and data reporting, provide contradicting results, lack crucial information to validate the results and exclude confounding factors, and finally show no causal relationship. Therefore, in our opinion, these publications cannot be used to substantiate, support, or conclude that decreases in blood thyroid (T4) hormone level on their own would result in impaired L&M in rats and are thus not adequate to use as fundament to ask for L&M testing as part of an EOGRTS.
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Affiliation(s)
- Josje H E Arts
- Nouryon Functional Chemicals B.V., Deventer, The Netherlands
| | - Frank Faulhammer
- GB Product Stewardship - Regulations, Toxicology and Ecology, BASF SE, Ludwigshafen, Germany
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Ford J, Riutta C, Kosian PA, O'Shaughessy K, Gilbert M. Reducing uncertainties in quantitative adverse outcome pathways by analysis of thyroid hormone in the neonatal rat brain. Toxicol Sci 2023; 193:192-203. [PMID: 37099719 PMCID: PMC10732312 DOI: 10.1093/toxsci/kfad040] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2023] Open
Abstract
A number of xenobiotics interfere with thyroid hormone (TH) signaling. Although adequate supplies of TH are necessary for normal brain development, regulatory reliance on serum TH as proxies for brain TH insufficiency is fraught with significant uncertainties. A more direct causal linkage to neurodevelopmental toxicity induced by TH-system disrupting chemicals is to measure TH in the target organ of most concern, the brain. However, the phospholipid-rich matrix of brain tissue presents challenges for TH extraction and measurement. We report optimized analytical procedures to extract TH in brain tissue of rats with recoveries >80% and low detection limits for T3, rT3, and T4 (0.013, 0.033, and 0.028 ng/g, respectively). Recovery of TH is augmented by enhancing phospholipid separation from TH using an anion exchange column coupled with a stringent column wash. Quality control measures incorporating a matrix-matched calibration procedure revealed excellent recovery and consistency across a large number of samples. Application of optimized procedures revealed age-dependent increases in neonatal brain T4, T3, and rT3 on the day of birth (postnatal day, PN0), PN2, PN6, and PN14. No sex-dependent differences in brain TH were observed at these ages, and similar TH levels were evident in perfused versus non-perfused brains. Implementation of a robust and reliable method to quantify TH in the fetal and neonatal rat brain will aid in the characterization of the thyroid-dependent chemical interference on neurodevelopment. A brain- in addition to a serum-based metric will reduce uncertainties in assessment of hazard and risk on the developing brain posed by thyroid system-disrupting chemicals.
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Affiliation(s)
- Jermaine Ford
- Center for Computational Toxicology and Exposure, Chemical Characterization and Exposure Division, US Environmental Protection Agency, Research Triangle Park, North Carolina 27709, USA
| | - Cal Riutta
- Oak Ridge Institute for Science Education, Oak Ridge, Tennessee 37830, USA
| | - Patricia A Kosian
- Center for Computational Toxicology and Exposure, Great Lakes Toxicology and Ecology Division, US Environmental Protection Agency, Duluth, Minnesota 55804, USA
| | - Katherine O'Shaughessy
- Center for Public Health and Environmental Assessment, Public Health Integrated Toxicology Division, US Environmental Protection Agency, Research Triangle Park, North Carolina 27709, USA
| | - Mary Gilbert
- Center for Public Health and Environmental Assessment, Public Health Integrated Toxicology Division, US Environmental Protection Agency, Research Triangle Park, North Carolina 27709, USA
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Marty MS, Sauer UG, Charlton A, Ghaffari R, Guignard D, Hallmark N, Hannas BR, Jacobi S, Marxfeld HA, Melching-Kollmuss S, Sheets LP, Urbisch D, Botham PA, van Ravenzwaay B. Towards a science-based testing strategy to identify maternal thyroid hormone imbalance and neurodevelopmental effects in the progeny-part III: how is substance-mediated thyroid hormone imbalance in pregnant/lactating rats or their progeny related to neurodevelopmental effects? Crit Rev Toxicol 2022; 52:546-617. [PMID: 36519295 DOI: 10.1080/10408444.2022.2130166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
This review investigated which patterns of thyroid- and brain-related effects are seen in rats upon gestational/lactational exposure to 14 substances causing thyroid hormone imbalance by four different modes-of-action (inhibition of thyroid peroxidase, sodium-iodide symporter and deiodinase activities, enhancement of thyroid hormone clearance) or to dietary iodine deficiency. Brain-related parameters included motor activity, cognitive function, acoustic startle response, hearing function, periventricular heterotopia, electrophysiology and brain gene expression. Specific modes-of-action were not related to specific patterns of brain-related effects. Based upon the rat data reviewed, maternal serum thyroid hormone levels do not show a causal relationship with statistically significant neurodevelopmental effects. Offspring serum thyroxine together with offspring serum triiodothyronine and thyroid stimulating hormone appear relevant to predict the likelihood for neurodevelopmental effects. Based upon the collated database, thresholds of ≥60%/≥50% offspring serum thyroxine reduction and ≥20% and statistically significant offspring serum triiodothyronine reduction indicate an increased likelihood for statistically significant neurodevelopmental effects; accuracies: 83% and 67% when excluding electrophysiology (and gene expression). Measurements of brain thyroid hormone levels are likely relevant, too. The extent of substance-mediated thyroid hormone imbalance appears more important than substance mode-of-action to predict neurodevelopmental impairment in rats. Pertinent research needs were identified, e.g. to determine whether the phenomenological offspring thyroid hormone thresholds are relevant for regulatory toxicity testing. The insight from this review shall be used to suggest a tiered testing strategy to determine whether gestational/lactational substance exposure may elicit thyroid hormone imbalance and potentially also neurodevelopmental effects.
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Affiliation(s)
| | - Ursula G Sauer
- Scientific Consultancy-Animal Welfare, Neubiberg, Germany
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Dal’ Bó IF, Teixeira ES, Rabi LT, Peres KC, Nascimento M, Chiamolera MI, Máximo V, Bufalo NE, Ward LS. Alternation between toxic and proliferative effects of Roundup® on human thyroid cells at different concentrations. Front Endocrinol (Lausanne) 2022; 13:904437. [PMID: 35992109 PMCID: PMC9382701 DOI: 10.3389/fendo.2022.904437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 07/05/2022] [Indexed: 11/21/2022] Open
Abstract
Endocrine-disrupting and carcinogenic effects of glyphosate have long been suspected, but little is known about the effect of compounds used in real life at different concentrations, neither in normal nor in thyroid tumor cells. As cancer cells may have different sensitivities and the effect of the product containing glyphosate may be different from that produced by the active ingredient alone, including the Acceptable Occupational Exposure Level (AOEL=160µg/L) and the Acceptable Daily Intake (ADI=830µg/L) determined by ANVISA, we used two human thyroid-derived cell lines, Nthy-ori 3-1 (from normal follicular cells) and TPC-1 (from papillary carcinoma), to test 15 different concentrations of Roundup® Original DI. Trypan blue (TB), CCK-8 and BrdU assays were used to evaluate cytotoxicity, metabolic activity and proliferation with 24h and 48h exposures in technical and biological triplicates. TB showed an important toxic effect, especially after 24h of exposure, in both cell lines. The AOEL concentration caused the death of 43% and 50% of the Nthy-ori and TPC-1 cells, respectively, in 24 h, while ADI resulted in 35% and 58% of cell death. After 48h of exposure, AOEL and ADI caused a lower number of dead Nthy-ori (33% and 18%) and TPC-1 (33% and 37%) cells, respectively, suggesting that the toxic effect of the product disappears and/or both strains have repair mechanisms that protect them from longer exposures. On the other hand, the CCK-8 assay showed that small concentrations of Roundup have a proliferative effect: 6.5µg/L increased the number of both Nthy-ori and TPC-1 cells at 24h, and the BrdU assay confirmed the stimulatory effect with a 321% increase in the absorbance of Nthy-ori cells at 48h. The herbicide produced even more frequent increases in the BrdU absorbance of TPC-1 cells, mainly at 24h. We conclude that thyroid cells exposed to Roundup present a nonmonotonic dual dose-response curve. Low concentrations of the pesticide, considered acceptable, cause significant cell death but also have an important proliferative effect, especially on TPC-1 cells. This herbicide, widely used around the world, may play a role in the increased incidence rate of thyroid nodules and cancer that has been observed in recent decades.
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Affiliation(s)
- Izabela Fernanda Dal’ Bó
- Laboratory of Cancer Molecular Genetics, School of Medical Sciences, University of Campinas, Campinas, Brazil
| | - Elisângela Souza Teixeira
- Laboratory of Cancer Molecular Genetics, School of Medical Sciences, University of Campinas, Campinas, Brazil
| | - Larissa Teodoro Rabi
- Laboratory of Cancer Molecular Genetics, School of Medical Sciences, University of Campinas, Campinas, Brazil
| | - Karina Colombera Peres
- Laboratory of Cancer Molecular Genetics, School of Medical Sciences, University of Campinas, Campinas, Brazil
| | - Matheus Nascimento
- Laboratory of Cancer Molecular Genetics, School of Medical Sciences, University of Campinas, Campinas, Brazil
| | | | - Valdemar Máximo
- Department of Medicine, Federal University of São Paulo, São Paulo, Brazil
- Institute for Research and Innovation in Health (i3S), University of Porto, Porto, Portugal
- Institute of Molecular Pathology and Immunology of the University of Porto (Ipatimup), Porto, Portugal
| | - Natássia Elena Bufalo
- Laboratory of Cancer Molecular Genetics, School of Medical Sciences, University of Campinas, Campinas, Brazil
- Department of Pathology, Faculty of Medicine of the University of Porto (FMUP), Porto, Portugal
| | - Laura Sterian Ward
- Laboratory of Cancer Molecular Genetics, School of Medical Sciences, University of Campinas, Campinas, Brazil
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13
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Ramhøj L, Svingen T, Mandrup K, Hass U, Lund SP, Vinggaard AM, Hougaard KS, Axelstad M. Developmental exposure to the brominated flame retardant DE-71 reduces serum thyroid hormones in rats without hypothalamic-pituitary-thyroid axis activation or neurobehavioral changes in offspring. PLoS One 2022; 17:e0271614. [PMID: 35853081 PMCID: PMC9295973 DOI: 10.1371/journal.pone.0271614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 07/01/2022] [Indexed: 11/19/2022] Open
Abstract
Polybrominated diphenyl ethers (PBDEs) are legacy flame retardants for which human exposure remains ubiquitous. This is of concern since these chemicals can perturb development and cause adverse health effects. For instance, DE-71, a technical mixture of PBDEs, can induce liver toxicity as well as reproductive and developmental toxicity. DE-71 can also disrupt the thyroid hormone (TH) system which may induce developmental neurotoxicity indirectly. However, in developmental toxicity studies, it remains unclear how DE-71 exposure affects the offspring’s thyroid hormone system and if this dose-dependently relates to neurodevelopmental effects. To address this, we performed a rat toxicity study by exposing pregnant dams to DE-71 at 0, 40 or 60 mg/kg/day during perinatal development from gestational day 7 to postnatal day 16. We assessed the TH system in both dams and their offspring, as well as potential hearing and neurodevelopmental effects in prepubertal and adult offspring. DE-71 significantly reduced serum T4 and T3 levels in both dams and offspring without a concomitant upregulation of TSH, thus inducing a hypothyroxinemia-like effect. No discernible effects were observed on the offspring’s brain function when assessed in motor activity boxes and in the Morris water maze, or on offspring hearing function. Our results, together with a thorough review of the literature, suggest that DE-71 does not elicit a clear dose-dependent relationship between low serum thyroxine (T4) and effects on the rat brain in standard behavioral assays. However, low serum TH levels are in themselves believed to be detrimental to human brain development, thus we propose that we lack assays to identify developmental neurotoxicity caused by chemicals disrupting the TH system through various mechanisms.
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Affiliation(s)
- Louise Ramhøj
- National Food Institute, Technical University of Denmark, Kgs. Lyngby, Denmark
- * E-mail:
| | - Terje Svingen
- National Food Institute, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Karen Mandrup
- National Food Institute, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Ulla Hass
- National Food Institute, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Søren Peter Lund
- National Research Centre for the Working Environment, Copenhagen, Denmark
| | | | - Karin Sørig Hougaard
- National Research Centre for the Working Environment, Copenhagen, Denmark
- Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - Marta Axelstad
- National Food Institute, Technical University of Denmark, Kgs. Lyngby, Denmark
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14
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Oliveira PFD, Trindade BBS, Reis PFM, Santos TFDC, Alves JCS, Santana DSD, Badauê-Passos Jr D. The Induction of Hypothyroidism During Gestation Decreases Outer Hair Cell Motility in Rat Offspring. Int Arch Otorhinolaryngol 2022; 26:e712-e717. [DOI: 10.1055/s-0042-1745856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 03/01/2022] [Indexed: 10/18/2022] Open
Abstract
Abstract
Introduction Perinatal hypothyroidism has a negative repercussion on the development and maturation of auditory system function. However, its long-term effect on auditory function remains unsettled.
Objective To evaluate the effect of prenatal hypothyroidism on the auditory function of adult offspring in rats.
Methods Pregnant Wistar rats were given the antithyroid drug methimazole (0.02% -1-methylimidazole-2-thiol– MMI) in drinking water, ad libitum, from gestational day (GD) 9 to postnatal day 15 (PND15). Anesthetized offspring from MMI-treated dams (OMTD) and control rats were evaluated by tympanometry, distortion product otoacoustic emission (DPOAE), and auditory brainstem response (ABR) at PNDs 30, 60, 90, and 120.
Results Our data demonstrated no middle ear dysfunction, with the OMTD compliance lower than that of the control group. The DPOAE revealed the absence of outer hair cells function, and the ABR showed normal integrity of neural auditory pathways up to brainstem level in the central nervous system. Furthermore, in the OMTD group, hearing loss was characterized by a higher electrophysiological threshold.
Conclusion Our data suggest that perinatal hypothyroidism leads to irreversible damage to cochlear function in offspring.
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Affiliation(s)
- Priscila Feliciano de Oliveira
- Department of Health Sciences, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
- Department of Speech, Language and Hearing, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
- Department of Physiology, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
| | | | | | | | - Julio Cesar Santana Alves
- Department of Health Sciences, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
- Department of Veterinary Medicine, Faculdade Pio Décimo , Aracaju, SE, Brazil
- Department of Physiology, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
| | - Demetrius Silva de Santana
- Department of Physiology, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
- Department of Science Computation, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil
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15
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Garg C, khan H, Kaur A, Singh TG, Sharma VK, Singh SK. Therapeutic Implications of Sonic Hedgehog Pathway in Metabolic Disorders: Novel Target for Effective Treatment. Pharmacol Res 2022; 179:106194. [DOI: 10.1016/j.phrs.2022.106194] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 03/24/2022] [Accepted: 03/24/2022] [Indexed: 12/13/2022]
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16
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Northcutt KV, Leal-Medina TS, Yoon YS. Early postnatal hypothyroidism reduces juvenile play behavior, but prenatal hypothyroidism compensates for these effects. Physiol Behav 2021; 241:113594. [PMID: 34536436 DOI: 10.1016/j.physbeh.2021.113594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 08/22/2021] [Accepted: 09/13/2021] [Indexed: 10/20/2022]
Abstract
Perinatal hypothyroidism causes long-lasting effects on behavior, including hyperactivity, cognitive delays/deficits, and a reduction in anxiety. Although there is some evidence that hypothyroidism during fetal development in humans has been associated with later autism spectrum disorder diagnosis or autism-like traits, the relationships between early thyroid hormones and social behaviors are largely unknown. Previously, we found that a moderate dose of the hypothyroid-inducing drug methimazole during embryonic and postnatal development dramatically increased juvenile play in male and female rats. The goal of the current study was to determine the extent to which thyroid hormones act in prenatal or postnatal development to organize later social behaviors. Subjects were exposed to methimazole in the drinking water during prenatal (embryonic day 12 to birth), postnatal (birth to postnatal day 23), or pre- and postnatal development; control animals received regular drinking water throughout the experiment. They were tested for play behavior as juveniles (P30-32). We found an interaction between pre- and postnatal methimazole administration such that postnatal hypothyroidism decreased some play behaviors, whereas sustained pre- and postnatal hypothyroidism restored play to control levels. The effects were similar in males and females. To our knowledge, this is the first report of an interaction between pre- and postnatal hypothyroidism on later behavior. The complexity of the timing of these effects may help explain why epidemiological studies have not consistently found a relationship between gestational hypothyroidism and later behavior.
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Affiliation(s)
- Katharine V Northcutt
- Biology Department and Neuroscience Program, Mercer University, 1501 Mercer University Dr., Macon, GA 31207, USA.
| | - Tanya S Leal-Medina
- Biology Department and Neuroscience Program, Mercer University, 1501 Mercer University Dr., Macon, GA 31207, USA
| | - Ye S Yoon
- Biology Department and Neuroscience Program, Mercer University, 1501 Mercer University Dr., Macon, GA 31207, USA
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17
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Ramhøj L, Svingen T, Frädrich C, Rijntjes E, Wirth EK, Pedersen K, Köhrle J, Axelstad M. Perinatal exposure to the thyroperoxidase inhibitors methimazole and amitrole perturbs thyroid hormone system signaling and alters motor activity in rat offspring. Toxicol Lett 2021; 354:44-55. [PMID: 34757178 DOI: 10.1016/j.toxlet.2021.10.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 10/15/2021] [Accepted: 10/26/2021] [Indexed: 01/12/2023]
Abstract
Disruption of the thyroid hormone system during development can impair brain development and cause irreversible damage. Some thyroid hormone system disruptors act by inhibiting the thyroperoxidase (TPO) enzyme, which is key to thyroid hormone synthesis. For the potent TPO-inhibiting drug propylthiouracil (PTU) this has been shown to result in thyroid hormone system disruption and altered brain development in animal studies. However, an outstanding question is which chemicals beside PTU can cause similar effects on brain development and to what degree thyroid hormone insufficiency must be induced to be able to measure adverse effects in rats and their offspring. To start answering these questions, we performed a perinatal exposure study in pregnant rats with two TPO-inhibitors: the drug methimazole (MMI) and the triazole herbicide amitrole. The study involved maternal exposure from gestational day 7 through to postnatal day 22, to MMI (8 and 16 mg/kg body weight/day) or amitrole (25 and 50 mg/kg body weight/day). Both MMI and amitrole reduced serum T4 concentrations in a dose-dependent manner in dams and offspring, with a strong activation of the hypothalamic-pituitary-thyroid axis. This reduction in serum T4 led to decreased thyroid hormone-mediated gene expression in the offspring's brains and caused adverse effects on brain function, seen as hyperactivity and decreased habituation in preweaning pups. These dose-dependent effects induced by MMI and amitrole are largely the same as those observed with PTU. This demonstrates that potent TPO-inhibitors can induce effects on brain development in rats and that these effects are driven by T4 deficiency. This knowledge will aid the identification of TPO-inhibiting thyroid hormone system disruptors in a regulatory context and can serve as a starting point in search of more sensitive markers of developmental thyroid hormone system disruption.
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Affiliation(s)
- Louise Ramhøj
- Division of Diet, Disease Prevention and Toxicology, National Food Institute, Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark
| | - Terje Svingen
- Division of Diet, Disease Prevention and Toxicology, National Food Institute, Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark
| | - Caroline Frädrich
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institut für Experimentelle Endokrinologie, 10115, Berlin, Germany
| | - Eddy Rijntjes
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institut für Experimentelle Endokrinologie, 10115, Berlin, Germany
| | - Eva K Wirth
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Department of Endocrinology and Metabolism and Charité Center for Cardiovascular Research, 10115, Berlin, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, Germany
| | - Katrine Pedersen
- Division of Diet, Disease Prevention and Toxicology, National Food Institute, Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark
| | - Josef Köhrle
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institut für Experimentelle Endokrinologie, 10115, Berlin, Germany
| | - Marta Axelstad
- Division of Diet, Disease Prevention and Toxicology, National Food Institute, Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark.
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18
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Gilbert ME, O'Shaughnessy KL, Thomas SE, Riutta C, Wood CR, Smith A, Oshiro WO, Ford RL, Hotchkiss MG, Hassan I, Ford JL. Thyroid Disruptors: Extrathyroidal Sites of Chemical Action and Neurodevelopmental Outcome-An Examination Using Triclosan and Perfluorohexane Sulfonate. Toxicol Sci 2021; 183:195-213. [PMID: 34460931 PMCID: PMC9038230 DOI: 10.1093/toxsci/kfab080] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Many xenobiotics are identified as potential thyroid disruptors due to their action to reduce circulating levels of thyroid hormone, most notably thyroxine (T4). Developmental neurotoxicity is a primary concern for thyroid disrupting chemicals yet correlating the impact of chemically induced changes in serum T4 to perturbed brain development remains elusive. A number of thyroid-specific neurodevelopmental assays have been proposed, based largely on the model thyroid hormone synthesis inhibitor propylthiouracil (PTU). This study examined whether thyroid disrupting chemicals acting distinct from synthesis inhibition would result in the same alterations in brain as expected with PTU. The perfluoroalkyl substance perfluorohexane sulfonate (50 mg/kg/day) and the antimicrobial Triclosan (300 mg/kg/day) were administered to pregnant rats from gestational day 6 to postnatal day (PN) 21, and a number of PTU-defined assays for neurotoxicity evaluated. Both chemicals reduced serum T4 but did not increase thyroid stimulating hormone. Both chemicals increased expression of hepatic metabolism genes, while thyroid hormone-responsive genes in the liver, thyroid gland, and brain were largely unchanged. Brain tissue T4 was reduced in newborns, but despite persistent T4 reductions in serum, had recovered in the PN6 pup brain. Neither treatment resulted in a low dose PTU-like phenotype in either brain morphology or neurobehavior, raising questions for the interpretation of serum biomarkers in regulatory toxicology. They further suggest that reliance on serum hormones as prescriptive of specific neurodevelopmental outcomes may be too simplistic and to understand thyroid-mediated neurotoxicity we must expand our thinking beyond that which follows thyroid hormone synthesis inhibition.
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Affiliation(s)
- Mary E Gilbert
- Center for Public Health and Environmental Assessment, Public Health Integrated Toxicology Division, US Environmental Protection Agency, Research Triangle Park, North Carolina 27709, USA
| | - Katherine L O'Shaughnessy
- Center for Public Health and Environmental Assessment, Public Health Integrated Toxicology Division, US Environmental Protection Agency, Research Triangle Park, North Carolina 27709, USA
| | - Susan E Thomas
- Oak Ridge Institute for Science Education, Oak Ridge, Tennesse 37830, USA
| | - Cal Riutta
- Oak Ridge Institute for Science Education, Oak Ridge, Tennesse 37830, USA
| | - Carmen R Wood
- Center for Public Health and Environmental Assessment, Public Health Integrated Toxicology Division, US Environmental Protection Agency, Research Triangle Park, North Carolina 27709, USA
| | - Alicia Smith
- Oak Ridge Institute for Science Education, Oak Ridge, Tennesse 37830, USA
| | - Wendy O Oshiro
- Center for Public Health and Environmental Assessment, Public Health Integrated Toxicology Division, US Environmental Protection Agency, Research Triangle Park, North Carolina 27709, USA
| | - Richard L Ford
- Oak Ridge Institute for Science Education, Oak Ridge, Tennesse 37830, USA
| | - Michelle Gatien Hotchkiss
- Center for Public Health and Environmental Assessment, Public Health Integrated Toxicology Division, US Environmental Protection Agency, Research Triangle Park, North Carolina 27709, USA
| | - Iman Hassan
- Center for Public Health and Environmental Assessment, Public Health Integrated Toxicology Division, US Environmental Protection Agency, Research Triangle Park, North Carolina 27709, USA
| | - Jermaine L Ford
- Center for Computational Toxicology and Exposure, Chemical Characterization and Exposure Division, US Environmental Protection Agency, Research Triangle Park, North Carolina 27709, USA
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19
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Ramhøj L, Frädrich C, Svingen T, Scholze M, Wirth EK, Rijntjes E, Köhrle J, Kortenkamp A, Axelstad M. Testing for heterotopia formation in rats after developmental exposure to selected in vitro inhibitors of thyroperoxidase. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 283:117135. [PMID: 33892370 DOI: 10.1016/j.envpol.2021.117135] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/23/2021] [Accepted: 04/09/2021] [Indexed: 06/12/2023]
Abstract
The thyroperoxidase (TPO) enzyme is expressed by the thyroid follicular cells and is required for thyroid hormone synthesis. In turn, thyroid hormones are essential for brain development, thus inhibition of TPO in early life can have life-long consequences for brain function. If environmental chemicals with the capacity to inhibit TPO in vitro can also alter brain development in vivo through thyroid hormone dependent mechanisms, however, remains unknown. In this study we show that the in vitro TPO inhibiting pesticide amitrole alters neuronal migration and induces periventricular heterotopia; a thyroid hormone dependent brain malformation. Perinatal exposure to amitrole reduced pup serum thyroxine (T4) concentrations to less than 50% of control animals and this insufficiency led to heterotopia formation in the 16-day old pup's brain. Two other in vitro TPO inhibitors, 2-mercaptobenzimidazole and cyanamide, caused reproductive toxicity and had only minor sporadic effects on the thyroid hormone system; consequently, they did not cause heterotopia. This is the first demonstration of an environmental chemical causing heterotopia, a brain malformation until now only reported for rodent studies with the anti-thyroid drugs propylthiouracil and methimazole. Our results highlight that certain TPO-inhibiting environmental chemicals can alter brain development through thyroid hormone dependent mechanisms. Improved understanding of the effects on the brain as well as the conditions under which chemicals can perturb brain development will be key to protect human health.
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Affiliation(s)
- Louise Ramhøj
- Division of Diet, Disease Prevention and Toxicology, National Food Institute, Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark
| | - Caroline Frädrich
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institut für Experimentelle Endokrinologie, 10115, Berlin, Germany
| | - Terje Svingen
- Division of Diet, Disease Prevention and Toxicology, National Food Institute, Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark
| | - Martin Scholze
- Division of Environmental Studies, College of Health, Medicine and Life Sciences, Brunel University London, Kingston Lane, Uxbridge, UB8 3PH, UK
| | - Eva K Wirth
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Department of Endocrinology and Metabolism, 10115, Berlin, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, Germany
| | - Eddy Rijntjes
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institut für Experimentelle Endokrinologie, 10115, Berlin, Germany
| | - Josef Köhrle
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institut für Experimentelle Endokrinologie, 10115, Berlin, Germany
| | - Andreas Kortenkamp
- Division of Environmental Studies, College of Health, Medicine and Life Sciences, Brunel University London, Kingston Lane, Uxbridge, UB8 3PH, UK
| | - Marta Axelstad
- Division of Diet, Disease Prevention and Toxicology, National Food Institute, Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark.
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20
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Haselman JT, Olker JH, Kosian PA, Korte JJ, Swintek JA, Denny JS, Nichols JW, Tietge JE, Hornung MW, Degitz SJ. Targeted Pathway-based In Vivo Testing Using Thyroperoxidase Inhibition to Evaluate Plasma Thyroxine as a Surrogate Metric of Metamorphic Success in Model Amphibian Xenopus laevis. Toxicol Sci 2021; 175:236-250. [PMID: 32176285 DOI: 10.1093/toxsci/kfaa036] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Chemical safety evaluation is in the midst of a transition from traditional whole-animal toxicity testing to molecular pathway-based in vitro assays and in silico modeling. However, to facilitate the shift in reliance on apical effects for risk assessment to predictive surrogate metrics having characterized linkages to chemical mechanisms of action, targeted in vivo testing is necessary to establish these predictive relationships. In this study, we demonstrate a means to predict thyroid-related metamorphic success in the model amphibian Xenopus laevis using relevant biochemical measurements during early prometamorphosis. The adverse outcome pathway for thyroperoxidase inhibition leading to altered amphibian metamorphosis was used to inform a pathway-based in vivo study design that generated response-response relationships. These causal relationships were used to develop Bayesian probabilistic network models that mathematically determine conditional dependencies between biochemical nodes and support the predictive capability of the biochemical profiles. Plasma thyroxine concentrations were the most predictive of metamorphic success with improved predictivity when thyroid gland sodium-iodide symporter gene expression levels (a compensatory response) were used in conjunction with plasma thyroxine as an additional regressor. Although thyroid-mediated amphibian metamorphosis has been studied for decades, this is the first time a predictive relationship has been characterized between plasma thyroxine and metamorphic success. Linking these types of biochemical surrogate metrics to apical outcomes is vital to facilitate the transition to the new paradigm of chemical safety assessments.
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Affiliation(s)
- Jonathan T Haselman
- Great Lakes Toxicology and Ecology Division, U.S. Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Duluth, Minnesota 55804
| | - Jennifer H Olker
- Great Lakes Toxicology and Ecology Division, U.S. Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Duluth, Minnesota 55804
| | - Patricia A Kosian
- Great Lakes Toxicology and Ecology Division, U.S. Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Duluth, Minnesota 55804
| | - Joseph J Korte
- Great Lakes Toxicology and Ecology Division, U.S. Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Duluth, Minnesota 55804
| | - Joseph A Swintek
- Badger Technical Services, Great Lakes Toxicology and Ecology Division, U.S. Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Duluth, Minnesota 55804
| | - Jeffrey S Denny
- Great Lakes Toxicology and Ecology Division, U.S. Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Duluth, Minnesota 55804
| | - John W Nichols
- Great Lakes Toxicology and Ecology Division, U.S. Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Duluth, Minnesota 55804
| | - Joseph E Tietge
- Great Lakes Toxicology and Ecology Division, U.S. Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Duluth, Minnesota 55804
| | - Michael W Hornung
- Great Lakes Toxicology and Ecology Division, U.S. Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Duluth, Minnesota 55804
| | - Sigmund J Degitz
- Great Lakes Toxicology and Ecology Division, U.S. Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Duluth, Minnesota 55804
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21
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Hassan I, El-Masri H, Ford J, Brennan A, Handa S, Paul Friedman K, Gilbert ME. Extrapolating In Vitro Screening Assay Data for Thyroperoxidase Inhibition to Predict Serum Thyroid Hormones in the Rat. Toxicol Sci 2020; 173:280-292. [PMID: 31697382 DOI: 10.1093/toxsci/kfz227] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Thyroperoxidase (TPO) is an enzyme essential for thyroid hormone (TH) synthesis and a target site for a number of xenobiotics that disrupt TH homeostasis. An in vitro high-throughput screening assay for TPO inhibition, the Amplex UltraRed-TPO (AUR-TPO), has been used to screen the ToxCast chemical libraries for this action. Output from this assay would be most useful if it could be readily translated into an in vivo response, namely a reduction of TH in serum. To this end, the relationship between TPO inhibition in vitro and serum TH decreases was examined in rats exposed to 2 classic TPO inhibitors, propylthiouracil (PTU) and methimazole (MMI). Serum and gland PTU, MMI, and TH levels were quantified using tandem liquid chromatography mass spectrometry. Thyroperoxidase activity was determined in thyroid gland microsomes treated with PTU or MMI in vitro and ex vivo from thyroid gland microsomes prepared from exposed animals. A quantitative model was constructed by contrasting in vitro and ex vivo AUR-TPO results and the in vivo time-course and dose-response analysis. In vitro:ex vivo correlations of AUR-TPO outputs indicated that less than 30% inhibition of TPO in vitro was sufficient to reduce serum T4 by 20%, a degree of regulatory significance. Although further testing of model estimates using other TPO inhibitors is essential for verification of these initial findings, the results of this study provide a means to translate in vitro screening assay results into predictions of in vivo serum T4 changes to inform risk assessment.
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Affiliation(s)
- Iman Hassan
- Toxicity Assessment Division.,National Health and Environmental Effects Research Laboratory
| | - Hisham El-Masri
- National Health and Environmental Effects Research Laboratory.,Integrated Systems Toxicology Division
| | - Jermaine Ford
- National Health and Environmental Effects Research Laboratory.,Analytical Chemistry Research Core/Research Cores Unit, US Environmental Protection Agency, Research Triangle Park, North Carolina
| | - Amanda Brennan
- National Health and Environmental Effects Research Laboratory.,Analytical Chemistry Research Core/Research Cores Unit, US Environmental Protection Agency, Research Triangle Park, North Carolina
| | - Sakshi Handa
- National Health and Environmental Effects Research Laboratory.,Integrated Systems Toxicology Division.,Oak Ridge Institute for Science Education, Oak Ridge, Tennessee
| | - Katie Paul Friedman
- National Center for Computational Toxicology, US Environmental Protection Agency, Research Triangle Park, North Carolina, 27711
| | - Mary E Gilbert
- Toxicity Assessment Division.,National Health and Environmental Effects Research Laboratory
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22
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Gilbert ME, O'Shaughnessy KL, Axelstad M. Regulation of Thyroid-disrupting Chemicals to Protect the Developing Brain. Endocrinology 2020; 161:bqaa106. [PMID: 32615585 PMCID: PMC8650774 DOI: 10.1210/endocr/bqaa106] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 06/30/2020] [Indexed: 12/18/2022]
Abstract
Synthetic chemicals with endocrine disrupting properties are pervasive in the environment and are present in the bodies of humans and wildlife. As thyroid hormones (THs) control normal brain development, and maternal hypothyroxinemia is associated with neurological impairments in children, chemicals that interfere with TH signaling are of considerable concern for children's health. However, identifying thyroid-disrupting chemicals (TDCs) in vivo is largely based on measuring serum tetraiodothyronine in rats, which may be inadequate to assess TDCs with disparate mechanisms of action and insufficient to evaluate the potential neurotoxicity of TDCs. In this review 2 neurodevelopmental processes that are dependent on TH action are highlighted, neuronal migration and maturation of gamma amino butyric acid-ergic interneurons. We discuss how interruption of these processes by TDCs may contribute to abnormal brain circuitry following developmental TH insufficiency. Finally, we identify issues in evaluating the developmental neurotoxicity of TDCs and the strengths and limitations of current approaches designed to regulate them. It is clear that an enhanced understanding of how THs affect brain development will lead to refined toxicity testing, reducing uncertainty and improving our ability to protect children's health.
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Affiliation(s)
- Mary E Gilbert
- Center for Public Health and Environmental Assessment, US Environmental Protection Agency, Research Triangle Park, North Carolina
| | - Katherine L O'Shaughnessy
- Center for Public Health and Environmental Assessment, US Environmental Protection Agency, Research Triangle Park, North Carolina
| | - Marta Axelstad
- Division of Diet, Disease Prevention and Toxicology, National Food Institute, Technical University of Denmark, Kgs. Lyngby, Denmark
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23
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Ramhøj L, Hass U, Gilbert ME, Wood C, Svingen T, Usai D, Vinggaard AM, Mandrup K, Axelstad M. Evaluating thyroid hormone disruption: investigations of long-term neurodevelopmental effects in rats after perinatal exposure to perfluorohexane sulfonate (PFHxS). Sci Rep 2020; 10:2672. [PMID: 32060323 PMCID: PMC7021709 DOI: 10.1038/s41598-020-59354-z] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 01/24/2020] [Indexed: 12/17/2022] Open
Abstract
Thyroid hormones are critical for mammalian brain development. Thus, chemicals that can affect thyroid hormone signaling during pregnancy are of great concern. Perfluorohexane sulfonate (PFHxS) is a widespread environmental contaminant found in human serum, breastmilk, and other tissues, capable of lowering serum thyroxine (T4) in rats. Here, we investigated its effects on the thyroid system and neurodevelopment following maternal exposure from early gestation through lactation (0.05, 5 or 25 mg/kg/day PFHxS), alone or in combination with a mixture of 12 environmentally relevant endocrine disrupting compounds (EDmix). PFHxS lowered thyroid hormone levels in both dams and offspring in a dose-dependent manner, but did not change TSH levels, weight, histology, or expression of marker genes of the thyroid gland. No evidence of thyroid hormone-mediated neurobehavioral disruption in offspring was observed. Since human brain development appear very sensitive to low T4 levels, we maintain that PFHxS is of potential concern to human health. It is our view that current rodent models are not sufficiently sensitive to detect adverse neurodevelopmental effects of maternal and perinatal hypothyroxinemia and that we need to develop more sensitive brain-based markers or measurable metrics of thyroid hormone-dependent perturbations in brain development.
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Affiliation(s)
- Louise Ramhøj
- Division of Diet, Disease Prevention and Toxicology, National Food Institute, Technical University of Denmark, Kgs. Lyngby, DK-2800,, Denmark
| | - Ulla Hass
- Division of Diet, Disease Prevention and Toxicology, National Food Institute, Technical University of Denmark, Kgs. Lyngby, DK-2800,, Denmark
| | - Mary E Gilbert
- Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - Carmen Wood
- Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - Terje Svingen
- Division of Diet, Disease Prevention and Toxicology, National Food Institute, Technical University of Denmark, Kgs. Lyngby, DK-2800,, Denmark
| | - Diana Usai
- Division of Diet, Disease Prevention and Toxicology, National Food Institute, Technical University of Denmark, Kgs. Lyngby, DK-2800,, Denmark
| | - Anne Marie Vinggaard
- Division of Diet, Disease Prevention and Toxicology, National Food Institute, Technical University of Denmark, Kgs. Lyngby, DK-2800,, Denmark
| | - Karen Mandrup
- Division of Diet, Disease Prevention and Toxicology, National Food Institute, Technical University of Denmark, Kgs. Lyngby, DK-2800,, Denmark
| | - Marta Axelstad
- Division of Diet, Disease Prevention and Toxicology, National Food Institute, Technical University of Denmark, Kgs. Lyngby, DK-2800,, Denmark.
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24
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Ferraris FK, Garcia EB, Chaves ADS, de Brito TM, Doro LH, Félix da Silva NM, Alves AS, Pádua TA, Henriques MDGMO, Cardoso Machado TS, Amendoeira FC. Exposure to the UV Filter Octyl Methoxy Cinnamate in the Postnatal Period Induces Thyroid Dysregulation and Perturbs the Immune System of Mice. Front Endocrinol (Lausanne) 2019; 10:943. [PMID: 32082254 PMCID: PMC7005579 DOI: 10.3389/fendo.2019.00943] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 12/31/2019] [Indexed: 02/05/2023] Open
Abstract
Evidence demonstrates the bidirectional communication and regulation between the neuroendocrine and immune systems. Thyroid hormones play key roles in nervous system development and can exert influence on various immune cells contributing to pathophysiological conditions. Octyl methoxycinnamate (OMC) is one of the most commonly used UV filters, and in vitro and in vivo studies have found thyroid disrupting effects. The present study assessed whether OMC administration in mice dams during the lactational period can cause thyroid disruption and generate immunologic alterations in the offspring. Indirect exposure to the OMC (1,000 mg/kg) in the lactational period affected neurodevelopment parameters, such as delayed eye-opening and weight gain in mice of both sexes, and these alterations are corroborated by the decrease in the T4 levels present in the pups' blood. No significant changes were observed in the thymus of these pups, but the number of lymphocytes increased in the spleen of the animals exposed to OMC, similar to the animals treated with propyl-thiouracil (PTU), a well-known thyroid disruptor. OMC modulated the percentage of leukocyte populations in peripheral blood, and the number of circulating polymorphonuclear cells increased two-fold. In vitro, OMC exhibited an inhibitory effect on splenocyte proliferation and IL-2 production induced by anti-CD3 antibody; however, this effect was reversed with the addition of T4 in the cell culture. In summary, the results of the present study demonstrate the influence of OMC on thyroid dysregulation and its impact on the modulation of the immune system in mice pups.
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Affiliation(s)
- Fausto Klabund Ferraris
- Laboratory of Pharmacology, Department of Pharmacology and Toxicology, National Institute of Health Quality Control (INCQS)—Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro, Brazil
| | - Esdras Barbosa Garcia
- Laboratory of Pharmacology, Department of Pharmacology and Toxicology, National Institute of Health Quality Control (INCQS)—Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro, Brazil
| | - Amanda da Silva Chaves
- Laboratory of Pharmacology, Department of Pharmacology and Toxicology, National Institute of Health Quality Control (INCQS)—Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro, Brazil
| | - Thais Morais de Brito
- Laboratory of Pharmacology, Department of Pharmacology and Toxicology, National Institute of Health Quality Control (INCQS)—Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro, Brazil
| | - Laís Higino Doro
- Laboratory of Pharmacology, Department of Pharmacology and Toxicology, National Institute of Health Quality Control (INCQS)—Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro, Brazil
| | - Naína Monsores Félix da Silva
- Laboratory of Pharmacology, Department of Pharmacology and Toxicology, National Institute of Health Quality Control (INCQS)—Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro, Brazil
| | - Amanda Soares Alves
- Laboratory of Pharmacology, Department of Pharmacology and Toxicology, National Institute of Health Quality Control (INCQS)—Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro, Brazil
| | - Tatiana Almeida Pádua
- Laboratory of Applied Pharmacology, Institute of Drug Technology (Far-Manguinhos)—Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro, Brazil
| | - Maria das Graças M. O. Henriques
- Laboratory of Applied Pharmacology, Institute of Drug Technology (Far-Manguinhos)—Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro, Brazil
| | - Tiago Savignon Cardoso Machado
- Laboratory of Professional Education in Laboratory Techniques in Health, Polytechnic School of Health Joaquim Venâncio—Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro, Brazil
| | - Fabio Coelho Amendoeira
- Laboratory of Pharmacology, Department of Pharmacology and Toxicology, National Institute of Health Quality Control (INCQS)—Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro, Brazil
- *Correspondence: Fabio Coelho Amendoeira
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25
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Amano I, Takatsuru Y, Khairinisa MA, Kokubo M, Haijima A, Koibuchi N. Effects of Mild Perinatal Hypothyroidism on Cognitive Function of Adult Male Offspring. Endocrinology 2018. [PMID: 29522169 DOI: 10.1210/en.2017-03125] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Mild perinatal hypothyroidism may result from inadequate iodine intake, insufficient treatment of congenital hypothyroidism, or exposure to endocrine-disrupting chemicals. Because thyroid hormones are critical for brain development, severe hypothyroidism that is untreated in infancy causes irreversible cretinism. Milder hypothyroidism may also affect cognitive development; however, the effects of mild and/or moderate hypothyroidism on brain development are not fully understood. In this study, we examined the behavior of adult male mice rendered mildly hypothyroid during the perinatal period using low-dose propylthiouracil (PTU). PTU was administered through drinking water (5 or 50 ppm) from gestational day 14 to postnatal day 21. Cognitive performance, studied by an object in-location test (OLT), was impaired in PTU-treated mice at postnatal week 8. These results suggest that, although the hypothyroidism was mild, it partially impaired cognitive function. We next measured the concentration of neurotransmitters (glutamate, γ-aminobutyric acid, and glycine) in the hippocampus using in vivo microdialysis during OLT. The concentrations of neurotransmitters, particularly glutamate and glycine, decreased in PTU-treated mice. The expression levels of N-methyl-d-aspartate receptor subunits, which are profound regulators of glutamate neurotransmission and memory function, also were decreased in PTU-treated mice. These data indicate that mild perinatal hypothyroidism causes cognitive disorders in adult offspring. Such disorders may be partially induced secondary to decreased concentrations of neurotransmitters and receptor expression.
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Affiliation(s)
- Izuki Amano
- Department of Integrative Physiology, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Yusuke Takatsuru
- Department of Integrative Physiology, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Miski Aghnia Khairinisa
- Department of Integrative Physiology, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Michifumi Kokubo
- Department of Integrative Physiology, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Asahi Haijima
- Department of Integrative Physiology, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Noriyuki Koibuchi
- Department of Integrative Physiology, Gunma University Graduate School of Medicine, Gunma, Japan
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26
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Fanibunda SE, Desouza LA, Kapoor R, Vaidya RA, Vaidya VA. Thyroid Hormone Regulation of Adult Neurogenesis. VITAMINS AND HORMONES 2018; 106:211-251. [DOI: 10.1016/bs.vh.2017.04.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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27
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Hassan I, El-Masri H, Kosian PA, Ford J, Degitz SJ, Gilbert ME. Neurodevelopment and Thyroid Hormone Synthesis Inhibition in the Rat: Quantitative Understanding Within the Adverse Outcome Pathway Framework. Toxicol Sci 2017; 160:57-73. [PMID: 28973696 PMCID: PMC10623382 DOI: 10.1093/toxsci/kfx163] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2023] Open
Abstract
Adequate levels of thyroid hormone (TH) are needed for proper brain development, deficiencies may lead to adverse neurologic outcomes in humans and animal models. Environmental chemicals have been linked to TH disruption, yet the relationship between developmental exposures and decline in serum TH resulting in neurodevelopmental impairment is poorly understood. The present study developed a quantitative adverse outcome pathway where serum thyroxin (T4) reduction following inhibition of thyroperoxidase in the thyroid gland are described and related to deficits in fetal brain TH and the development of a brain malformation, cortical heterotopia. Pregnant rats were exposed to 6-propylthiouracil (PTU 0, 0.1, 0.5, 1, 2, or 3 parts per million [ppm]) from gestational days 6-20, sequentially increasing PTU concentrations in maternal thyroid gland and serum as well as in fetal serum. Dams exposed to 0.5 ppm PTU and higher exhibited dose-dependent decreases in thyroidal T4. Serum T4 levels in the dam were significantly decreased with exposure to 2 and 3 ppm PTU. In the fetus, T4 decrements were first observed at a lower dose of 0.5 ppm PTU. Based on these data, fetal brain T4 levels were estimated from published literature sources, and quantitatively linked to increases in the size of the heterotopia present in the brains of offspring. These data show the potential of in vivo assessments and computational descriptions of biologic responses to predict the development of this structural brain malformation and use of quantitative adverse outcome pathway approach to evaluate brain deficits that may result from exposure to other TH disruptors.
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Affiliation(s)
| | - Hisham El-Masri
- Integrated Systems Toxicology Division, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Research Triangle Park, North Carolina 27709
| | - Patricia A Kosian
- Mid-Continent Ecology Division, National Health and Environmental Effects Research Lab, US Environmental Protection Agency, Duluth, Minnesota 55804
| | - Jermaine Ford
- Analytical Chemistry Research Core/Research Cores Unit, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Research Triangle Park, North Carolina 27709
| | - Sigmund J Degitz
- Mid-Continent Ecology Division, National Health and Environmental Effects Research Lab, US Environmental Protection Agency, Duluth, Minnesota 55804
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28
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Rebuttal to letter by Morfeld et al., “Boberg et al. (2011) – Corrigendum (2016): Further significant modifications needed”. Reprod Toxicol 2017; 71:162-163. [DOI: 10.1016/j.reprotox.2017.03.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 12/21/2016] [Accepted: 03/21/2017] [Indexed: 11/20/2022]
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29
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Raymaekers SR, Darras VM. Thyroid hormones and learning-associated neuroplasticity. Gen Comp Endocrinol 2017; 247:26-33. [PMID: 28390960 DOI: 10.1016/j.ygcen.2017.04.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 03/30/2017] [Accepted: 04/03/2017] [Indexed: 12/11/2022]
Abstract
Thyroid hormones (THs) are crucial for brain development and maturation in all vertebrates. Especially during pre- and perinatal development, disruption of TH signaling leads to a multitude of neurological deficits. Many animal models provided insight in the role of THs in brain development, but specific data on how they affect the brain's ability to learn and adapt depending on environmental stimuli are rather limited. In this review, we focus on a number of learning processes like spatial learning, fear conditioning, vocal learning and imprinting behavior and on how abnormal TH signaling during development shapes subsequent performance. It is clear from multiple studies that TH deprivation leads to defects in learning on all fronts, and interestingly, changes in local expression of the TH activator deiodinase type 2 seem to have an important role. Taking into account that THs are regulated in a very space-specific manner, there is thus increasing pressure to investigate more local TH regulators as potential factors involved in neuroplasticity. As these learning processes are also important for proper adult human functioning, further elucidating the role of THs in developmental neuroplasticity in various animal models is an important field for advancing both fundamental and applied knowledge on human brain function.
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Affiliation(s)
- Sander R Raymaekers
- Laboratory of Comparative Endocrinology, Biology Department, KU Leuven, Naamsestraat 61, 3000 Leuven, Belgium
| | - Veerle M Darras
- Laboratory of Comparative Endocrinology, Biology Department, KU Leuven, Naamsestraat 61, 3000 Leuven, Belgium.
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30
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Gilbert M, Goodman J, Gomez J, Johnstone A, Ramos R. Adult hippocampal neurogenesis is impaired by transient and moderate developmental thyroid hormone disruption. Neurotoxicology 2017; 59:9-21. [DOI: 10.1016/j.neuro.2016.12.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 12/21/2016] [Accepted: 12/28/2016] [Indexed: 11/28/2022]
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31
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Moog NK, Entringer S, Heim C, Wadhwa PD, Kathmann N, Buss C. Influence of maternal thyroid hormones during gestation on fetal brain development. Neuroscience 2017; 342:68-100. [PMID: 26434624 PMCID: PMC4819012 DOI: 10.1016/j.neuroscience.2015.09.070] [Citation(s) in RCA: 221] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 09/22/2015] [Accepted: 09/25/2015] [Indexed: 01/09/2023]
Abstract
Thyroid hormones (THs) play an obligatory role in many fundamental processes underlying brain development and maturation. The developing embryo/fetus is dependent on maternal supply of TH. The fetal thyroid gland does not commence TH synthesis until mid gestation, and the adverse consequences of severe maternal TH deficiency on offspring neurodevelopment are well established. Recent evidence suggests that even more moderate forms of maternal thyroid dysfunction, particularly during early gestation, may have a long-lasting influence on child cognitive development and risk of neurodevelopmental disorders. Moreover, these observed alterations appear to be largely irreversible after birth. It is, therefore, important to gain a better understanding of the role of maternal thyroid dysfunction on offspring neurodevelopment in terms of the nature, magnitude, time-specificity, and context-specificity of its effects. With respect to the issue of context specificity, it is possible that maternal stress and stress-related biological processes during pregnancy may modulate maternal thyroid function. The possibility of an interaction between the thyroid and stress systems in the context of fetal brain development has, however, not been addressed to date. We begin this review with a brief overview of TH biology during pregnancy and a summary of the literature on its effect on the developing brain. Next, we consider and discuss whether and how processes related to maternal stress and stress biology may interact with and modify the effects of maternal thyroid function on offspring brain development. We synthesize several research areas and identify important knowledge gaps that may warrant further study. The scientific and public health relevance of this review relates to achieving a better understanding of the timing, mechanisms and contexts of thyroid programing of brain development, with implications for early identification of risk, primary prevention and intervention.
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Affiliation(s)
- N K Moog
- Department of Medical Psychology, Charité University Medicine Berlin, Luisenstrasse 57, 10117 Berlin, Germany
| | - S Entringer
- Department of Medical Psychology, Charité University Medicine Berlin, Luisenstrasse 57, 10117 Berlin, Germany; University of California, Irvine, Development, Health, and Disease Research Program, 333 The City Drive West, Suite 1200, Orange, CA 92868, USA; Department of Pediatrics, University of California, Irvine, School of Medicine, 505 South Main Street, Suite 525, Orange, CA 92868, USA
| | - C Heim
- Department of Medical Psychology, Charité University Medicine Berlin, Luisenstrasse 57, 10117 Berlin, Germany; Department of Biobehavioral Health, Pennsylvania State University, College of Health and Human Development, 219 Biobehavioral Health Building, University Park, PA 16802, USA
| | - P D Wadhwa
- University of California, Irvine, Development, Health, and Disease Research Program, 333 The City Drive West, Suite 1200, Orange, CA 92868, USA; Department of Pediatrics, University of California, Irvine, School of Medicine, 505 South Main Street, Suite 525, Orange, CA 92868, USA; Department of Psychiatry and Human Behavior, University of California, Irvine, School of Medicine, 3117 Gillespie Neuroscience Research Facility, 837 Health Sciences Drive, Irvine, CA 92697, USA; Department of Obstetrics and Gynecology, University of California, Irvine, School of Medicine, 3117 Gillespie Neuroscience Research Facility, 837 Health Sciences Drive, Irvine, CA 92697, USA; Department of Epidemiology, University of California, Irvine, School of Medicine, 3117 Gillespie Neuroscience Research Facility, 837 Health Sciences Drive, Irvine, CA 92697, USA
| | - N Kathmann
- Department of Clinical Psychology, Humboldt-Universität zu Berlin, Rudower Chaussee 18, 12489 Berlin, Germany
| | - C Buss
- Department of Medical Psychology, Charité University Medicine Berlin, Luisenstrasse 57, 10117 Berlin, Germany; University of California, Irvine, Development, Health, and Disease Research Program, 333 The City Drive West, Suite 1200, Orange, CA 92868, USA; Department of Pediatrics, University of California, Irvine, School of Medicine, 505 South Main Street, Suite 525, Orange, CA 92868, USA.
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32
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Pei Y, Peng J, Behl M, Sipes NS, Shockley KR, Rao MS, Tice RR, Zeng X. Comparative neurotoxicity screening in human iPSC-derived neural stem cells, neurons and astrocytes. Brain Res 2016; 1638:57-73. [PMID: 26254731 PMCID: PMC5032144 DOI: 10.1016/j.brainres.2015.07.048] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 07/24/2015] [Accepted: 07/28/2015] [Indexed: 12/14/2022]
Abstract
Induced pluripotent stem cells (iPSC) and their differentiated derivatives offer a unique source of human primary cells for toxicity screens. Here, we report on the comparative cytotoxicity of 80 compounds (neurotoxicants, developmental neurotoxicants, and environmental compounds) in iPSC as well as isogenic iPSC-derived neural stem cells (NSC), neurons, and astrocytes. All compounds were tested over a 24-h period at 10 and 100 μM, in duplicate, with cytotoxicity measured using the MTT assay. Of the 80 compounds tested, 50 induced significant cytotoxicity in at least one cell type; per cell type, 32, 38, 46, and 41 induced significant cytotoxicity in iPSC, NSC, neurons, and astrocytes, respectively. Four compounds (valinomycin, 3,3',5,5'-tetrabromobisphenol, deltamethrin, and triphenyl phosphate) were cytotoxic in all four cell types. Retesting these compounds at 1, 10, and 100 μM using the same exposure protocol yielded consistent results as compared with the primary screen. Using rotenone, we extended the testing to seven additional iPSC lines of both genders; no substantial difference in the extent of cytotoxicity was detected among the cell lines. Finally, the cytotoxicity assay was simplified by measuring luciferase activity using lineage-specific luciferase reporter iPSC lines which were generated from the parental iPSC line. This article is part of a Special Issue entitled SI: PSC and the brain.
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Affiliation(s)
- Ying Pei
- XCell Science Inc., Novato, CA, USA
| | - Jun Peng
- Buck Institute for Research on Aging, Novato, CA, USA
| | - Mamta Behl
- National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27713, USA
| | - Nisha S Sipes
- National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27713, USA
| | - Keith R Shockley
- National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27713, USA
| | | | - Raymond R Tice
- National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27713, USA
| | - Xianmin Zeng
- XCell Science Inc., Novato, CA, USA; Buck Institute for Research on Aging, Novato, CA, USA.
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33
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Hass U, Christiansen S, Boberg J, Rasmussen MG, Mandrup K, Axelstad M. Low-dose effect of developmental bisphenol A exposure on sperm count and behaviour in rats. Andrology 2016; 4:594-607. [PMID: 27089241 DOI: 10.1111/andr.12176] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 01/25/2016] [Accepted: 01/28/2016] [Indexed: 01/10/2023]
Abstract
Bisphenol A is widely used in food contact materials and other products and is detected in human urine and blood. Bisphenol A may affect reproductive and neurological development; however, opinion of the European Food Safety Authority (EFSA) on bisphenol A (EFSA J, 13, 2015 and 3978) concluded that none of the available studies were robust enough to provide a point of departure for setting a tolerable daily intake for bisphenol A. In the present study, pregnant Wistar rats (n = 17-21) were gavaged from gestation day 7 to pup day 22 with bisphenol A doses of 0, 25 μg, 250 μg, 5 mg or 50 mg/kg bw/day. In the offspring, growth, sexual maturation, weights and histopathology of reproductive organs, oestrus cyclicity and sperm counts were assessed. Neurobehavioural development was investigated using a behavioural testing battery including tests for motor activity, sweet preference, anxiety and spatial learning. Decreased sperm count was found at the lowest bisphenol A dose, that is 25 μg/kg/day, but not at the higher doses. Reproductive organ weight and histology were not affected and no behavioural effects were seen in male offspring. In the female offspring, exposure to 25 μg/kg bw/day bisphenol A dose resulted in increased body weight late in life and altered spatial learning in a Morris water maze, indicating masculinization of the brain. Decreased intake of sweetened water was seen in females from the highest bisphenol A dose group, also a possible sign of masculinization. The other investigated endpoints were not significantly affected. In conclusion, the present study using a robust experimental study design, has shown that developmental exposure to 25 μg/kg bw/day bisphenol A can cause adverse effects on fertility (decreased sperm count), neurodevelopment (masculinization of spatial learning in females) and lead to increased female body weight late in life. These results suggest that the new EFSA temporary tolerable daily intake of 4 μg/kg bw/day is not sufficiently protective with regard to endocrine disrupting effects of bisphenol A in humans.
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Affiliation(s)
- U Hass
- National Food Institute, Division of Diet, Disease Prevention and Toxicology, Technical University of Denmark, Søborg, Denmark
| | - S Christiansen
- National Food Institute, Division of Diet, Disease Prevention and Toxicology, Technical University of Denmark, Søborg, Denmark
| | - J Boberg
- National Food Institute, Division of Diet, Disease Prevention and Toxicology, Technical University of Denmark, Søborg, Denmark
| | - M G Rasmussen
- National Food Institute, Division of Diet, Disease Prevention and Toxicology, Technical University of Denmark, Søborg, Denmark
| | - K Mandrup
- National Food Institute, Division of Diet, Disease Prevention and Toxicology, Technical University of Denmark, Søborg, Denmark
| | - M Axelstad
- National Food Institute, Division of Diet, Disease Prevention and Toxicology, Technical University of Denmark, Søborg, Denmark
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Gilbert ME, Sanchez-Huerta K, Wood C. Mild Thyroid Hormone Insufficiency During Development Compromises Activity-Dependent Neuroplasticity in the Hippocampus of Adult Male Rats. Endocrinology 2016; 157:774-87. [PMID: 26606422 DOI: 10.1210/en.2015-1643] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Severe thyroid hormone (TH) deficiency during critical phases of brain development results in irreversible neurological and cognitive impairments. The mechanisms accounting for this are likely multifactorial, and are not fully understood. Here we pursue the possibility that one important element is that TH affects basal and activity-dependent neurotrophin expression in brain regions important for neural processing. Graded exposure to propylthiouracil (PTU) during development produced dose-dependent reductions in mRNA expression of nerve growth factor (Ngf) in whole hippocampus of neonates. These changes in basal expression persisted to adulthood despite the return to euthyroid conditions in blood. In contrast to small PTU-induced reductions in basal expression of several genes, developmental PTU treatment dramatically reduced the activity-dependent expression of neurotrophins and related genes (Bdnft, Bdnfiv, Arc, and Klf9) in adulthood and was accompanied by deficits in hippocampal-based learning. These data demonstrate that mild TH insufficiency during development not only reduces expression of important neurotrophins that persists into adulthood but also severely restricts the activity-dependent induction of these genes. Considering the importance of these neurotrophins for sculpting the structural and functional synaptic architecture in the developing and the mature brain, it is likely that TH-mediated deficits in these plasticity mechanisms contribute to the cognitive deficiencies that accompany developmental TH compromise.
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Affiliation(s)
- M E Gilbert
- Toxicity Assessment Division (M.E.G., C.W.), National Health and Environmental Effects Research Laboratory, United States Environmental Protection Agency, Research Triangle Park, North Carolina 27709; Departamento de Fisiología "Mauricio Russek" (K.S.-H.), Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico 07738
| | - K Sanchez-Huerta
- Toxicity Assessment Division (M.E.G., C.W.), National Health and Environmental Effects Research Laboratory, United States Environmental Protection Agency, Research Triangle Park, North Carolina 27709; Departamento de Fisiología "Mauricio Russek" (K.S.-H.), Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico 07738
| | - C Wood
- Toxicity Assessment Division (M.E.G., C.W.), National Health and Environmental Effects Research Laboratory, United States Environmental Protection Agency, Research Triangle Park, North Carolina 27709; Departamento de Fisiología "Mauricio Russek" (K.S.-H.), Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico 07738
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Ahmed RG, Abdel-Latif M, Ahmed F. Protective effects of GM-CSF in experimental neonatal hypothyroidism. Int Immunopharmacol 2015; 29:538-543. [PMID: 26453507 DOI: 10.1016/j.intimp.2015.10.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 09/27/2015] [Accepted: 10/01/2015] [Indexed: 12/18/2022]
Abstract
Hypothyroidism induced by methimazole (MMI), has a negative impact on the postnatal development. Neonatal Granulocyte Macrophage-Colony Stimulating Factor [GM-CSF; 50μg/kg, intramuscular injection at postnatal day (PND) 17] had been tested to ameliorate the effects of MMI [0.05%, (weight per volume; w/v), intraperitoneal injection at PND 15]-induced hypothyroidism in Wistar rats. The hypothyroid conditions due to the administration of MMI produced inhibitory effects on neonatal serum thyroxine (T4), 3,5,3'-triiodothyronine (T3), neutrophil count in bone marrow and blood, cerebellar glutathione (GSH) and acetylcholinesterase (AchE), although it induced stimulatory actions on serum thyrotropin (TSH), growth hormone (GH), insulin growth factor-II (IGF-II), tumor necrosis factor alpha (TNF-α), and cerebellar malondialdehyde (MDA) at PND 19. The treatment with GM-CSF could reverse the depressing and stimulating effects of MMI on these markers except for cerebellar AchE where its enhancement was non-significant (P>0.05) at tested PND. Thus, neonatal GM-CSF may be responsible for suppressing autoimmune responses and preventing hypothyroidism.
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Affiliation(s)
- R G Ahmed
- Division of Anatomy and Embryology, Zoology Department, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt.
| | - M Abdel-Latif
- Division of Immunity, Zoology Department, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt
| | - F Ahmed
- Immunity and Microbiology Department, Faculty of Pharmacy, Beni-Suef University, Beni-Suef, Egypt
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Kapoor R, Fanibunda SE, Desouza LA, Guha SK, Vaidya VA. Perspectives on thyroid hormone action in adult neurogenesis. J Neurochem 2015; 133:599-616. [DOI: 10.1111/jnc.13093] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 02/18/2015] [Accepted: 02/24/2015] [Indexed: 12/25/2022]
Affiliation(s)
- Richa Kapoor
- Department of Biological Sciences; Tata Institute of Fundamental Research; Mumbai India
| | - Sashaina E. Fanibunda
- Department of Biological Sciences; Tata Institute of Fundamental Research; Mumbai India
| | - Lynette A. Desouza
- Department of Biological Sciences; Tata Institute of Fundamental Research; Mumbai India
| | - Suman K. Guha
- Department of Biological Sciences; Tata Institute of Fundamental Research; Mumbai India
| | - Vidita A. Vaidya
- Department of Biological Sciences; Tata Institute of Fundamental Research; Mumbai India
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Sánchez-Huerta K, Pacheco-Rosado J, Gilbert ME. Adult onset-hypothyroidism: alterations in hippocampal field potentials in the dentate gyrus are largely associated with anaesthesia-induced hypothermia. J Neuroendocrinol 2015; 27:8-19. [PMID: 25327136 DOI: 10.1111/jne.12229] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 09/16/2014] [Accepted: 10/03/2014] [Indexed: 01/10/2023]
Abstract
Thyroid hormone (TH) is essential for a number of physiological processes and is particularly critical during nervous system development. The hippocampus is strongly implicated in cognition and is sensitive to developmental hypothyroidism. The impact of TH insufficiency in the foetus and neonate on hippocampal synaptic function has been fairly well characterised. Although adult onset hypothyroidism has also been associated with impairments in cognitive function, studies of hippocampal synaptic function with late onset hypothyroidism have yielded inconsistent results. In the present study, we report hypothyroidism induced by the synthesis inhibitor propylthiouracil (10 p.p.m., 0.001%, minimum of 4 weeks), resulted in marginal alterations in excitatory postsynaptic potential (EPSP) and population spike (PS) amplitude in the dentate gyrus measured in vivo. No effects were seen in tests of short-term plasticity, and a minor enhancement of long-term potentiation of the EPSP slope was observed. The most robust synaptic alteration evident in hypothyroid animals was an increase in synaptic response latency, which was paralleled by a failure to maintain normal body temperature under anaesthesia, despite warming on a heating pad. Latency shifts could be reversed in hypothyroid animals by increasing the external heat source and, conversely, synaptic delays could be induced in control animals by removing the heat source, with a consequent drop in body and brain temperature. Thermoregulation is TH- dependent, and anaesthesia necessary for surgical procedures posed a thermoregulatory challenge that was differentially met in control and hypothyroid animals. Minor increases in field potential EPSP slope, decreases in PS amplitudes and increased latencies are consistent with previous reports of hypothermia in naive control rats. We conclude that failures in thyroid-dependent temperature regulation rather than direct action of TH in synaptic physiology are responsible for the observed effects. These findings stand in contrast to the synaptic impairments observed in adult offspring following developmental TH insufficiency, and emphasise the need to control for the potential unintended consequences of hypothermia in the interpretation of hypothyroid-induced changes in physiological systems, most notably synaptic transmission.
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Affiliation(s)
- K Sánchez-Huerta
- Departamento de Fisiología 'Mauricio Russek', Escuela Nacional de Ciencias Biológicas, IPN, México City, México; Laboratory of Neurochemistry, National Institute of Pediatrics, Mexico City, Mexico
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Tanaka T, Wang L, Kimura M, Abe H, Mizukami S, Yoshida T, Shibutani M. Developmental Hypothyroidism Abolishes Bilateral Differences in Sonic Hedgehog Gene Control in the Rat Hippocampal Dentate Gyrus. Toxicol Sci 2014; 144:128-37. [DOI: 10.1093/toxsci/kfu266] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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Leach PT, Holliday E, Kutlu MG, Gould TJ. Withdrawal From Chronic Nicotine Reduces Thyroid Hormone Levels and Levothyroxine Treatment Ameliorates Nicotine Withdrawal-Induced Deficits in Hippocampus-Dependent Learning in C57BL/6J Mice. Nicotine Tob Res 2014; 17:690-6. [PMID: 25358661 DOI: 10.1093/ntr/ntu229] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 10/20/2014] [Indexed: 11/13/2022]
Abstract
INTRODUCTION Cigarette smoking alters a variety of endocrine systems including thyroid hormones. Altered thyroid hormone signaling may lead to a subclinical or overt hypothyroid condition that could contribute to nicotine withdrawal-related symptoms, such as cognitive deficits. Thus, normalizing thyroid hormone levels may represent a novel therapeutic target for ameliorating nicotine withdrawal-associated cognitive deficits. METHODS The current studies conducted an analysis of serum thyroid hormone levels after chronic and withdrawal from chronic nicotine treatment in C57BL/6J mice using an enzyme-linked immunosorbent assay. The present studies also evaluated the effect of synthetic thyroid hormone (levothyroxine) on contextual and cued memory. RESULTS The current studies found that nicotine withdrawal reduces secreted thyroid hormone levels by 9% in C57BL/6J mice. Further, supplemental thyroid hormone not only enhanced memory in naïve animals, but also ameliorated deficits in hippocampus-dependent learning associated with nicotine withdrawal. CONCLUSIONS These results suggest that smokers attempting to quit should be monitored closely for changes in thyroid function. If successfully treated, normalization of thyroid hormone levels may ameliorate some deficits associated with nicotine withdrawal and this may lead to higher rates of successful abstinence.
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Affiliation(s)
- Prescott T Leach
- Temple University Department of Psychology, Neuroscience Program, Temple University, Philadelphia, PA
| | - Erica Holliday
- Temple University Department of Psychology, Neuroscience Program, Temple University, Philadelphia, PA
| | - Munir G Kutlu
- Temple University Department of Psychology, Neuroscience Program, Temple University, Philadelphia, PA
| | - Thomas J Gould
- Temple University Department of Psychology, Neuroscience Program, Temple University, Philadelphia, PA
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Gilbert ME, Ramos RL, McCloskey DP, Goodman JH. Subcortical band heterotopia in rat offspring following maternal hypothyroxinaemia: structural and functional characteristics. J Neuroendocrinol 2014; 26:528-41. [PMID: 24889016 DOI: 10.1111/jne.12169] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 05/19/2014] [Accepted: 05/28/2014] [Indexed: 01/22/2023]
Abstract
Thyroid hormones (TH) play crucial roles in brain maturation and are important for neuronal migration and neocortical lamination. Subcortical band heterotopia (SBH) represent a class of neuronal migration errors in humans that are often associated with childhood epilepsy. We have previously reported the presence of SBH in a rodent model of low level hypothyroidism induced by maternal exposure to the goitrogen, propylthiouracil (PTU). In the present study, we report the dose-response characteristics of this developmental malformation and the connectivity of heterotopic neurones with other brain regions, as well as their functionality. Pregnant rats were exposed to varying concentrations of PTU through the drinking water (0-10 p.p.m.) beginning on gestational day 6 to produce graded levels of TH insufficiency. Dose-dependent increases in the volume of the SBH present in the corpus callosum were documented in the adult offspring, with a clear presence at concentrations of PTU that resulted in minor (< 15%) reductions in maternal serum thyroxine as measured when pups were weaned. SBH contain neurones, oligodendrocytes, astrocytes and microglia. Monoaminergic and cholinergic processes were prevalent and many of the axons were myelinated. Anatomical connectivity of SBH neurones to cortical neurones and the synaptic functionality of these anatomical connections was verified by ex vivo field potential recordings. SBH persisted in adult offspring despite a return to euthyroid status on termination of exposure and these offspring displayed an increased sensitivity to seizures. Features of this model are attractive with respect to the investigation of the molecular mechanisms of cortical development, the effectiveness of therapeutic intervention in hypothyroxinaemia during pregnancy and the impact of the very modest TH imbalance that accompanies exposure to environmental contaminants.
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Affiliation(s)
- M E Gilbert
- Toxicity Assessment Division, Neurotoxicology Branch, US Environmental Protection Agency, Research Triangle Park, NC, USA
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Shiraki A, Saito F, Akane H, Takeyoshi M, Imatanaka N, Itahashi M, Yoshida T, Shibutani M. Expression alterations of genes on both neuronal and glial development in rats after developmental exposure to 6-propyl-2-thiouracil. Toxicol Lett 2014; 228:225-34. [PMID: 24780913 DOI: 10.1016/j.toxlet.2014.04.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 04/19/2014] [Accepted: 04/20/2014] [Indexed: 12/31/2022]
Abstract
The present study was performed to determine target gene profiles associated with pathological mechanisms of developmental neurotoxicity. For this purpose, we selected a rat developmental hypothyroidism model because thyroid hormones play an essential role in both neuronal and glial development. Region-specific global gene expression analysis was performed at postnatal day (PND) 21 on four brain regions representing different structures and functions, i.e., the cerebral cortex, corpus callosum, dentate gyrus and cerebellar vermis of rats exposed to 6-propyl-2-thiouracil in the drinking water at 3 and 10ppm from gestational day 6 to PND 21. Expression changes of gene clusters of neuron differentiation and development, cell migration, synaptic function, and axonogenesis were detected in all four regions. Characteristically, gene expression profiles suggestive of affection of ephrin signaling and glutamate transmission were obtained in multiple brain regions. Gene clusters suggestive of suppression of myelination and glial development were specifically detected in the corpus callosum and cerebral cortex. Immunohistochemically, immature astrocytes immunoreactive for vimentin and glial fibrillary acidic protein were increased, and oligodendrocytes immunoreactive for oligodendrocyte lineage transcription factor 2 were decreased in the corpus callosum. Immunoreactive intensity of myelin basic protein was also decreased in the corpus callosum and cerebral cortex. The hippocampal dentate gyrus showed downregulation of Ptgs2, which is related to synaptic activity and neurogenesis, as well as a decrease of cyclooxygenase-2-immunoreactive granule cells, suggesting an impaired synaptic function related to neurogenesis. These results suggest that multifocal brain region-specific microarray analysis can determine the affection of neuronal or glial development.
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Affiliation(s)
- Ayako Shiraki
- Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan; Pathogenetic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu-shi, Gifu 501-1193, Japan
| | - Fumiyo Saito
- Chemicals Evaluation and Research Institute, Japan, 1-4-25 Koraku, Bunkyo-ku, Tokyo 112-0004, Japan
| | - Hirotoshi Akane
- Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan
| | - Masahiro Takeyoshi
- Chemicals Evaluation and Research Institute, Japan, 1-4-25 Koraku, Bunkyo-ku, Tokyo 112-0004, Japan
| | - Nobuya Imatanaka
- Chemicals Evaluation and Research Institute, Japan, 1-4-25 Koraku, Bunkyo-ku, Tokyo 112-0004, Japan
| | - Megu Itahashi
- Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan; Pathogenetic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu-shi, Gifu 501-1193, Japan
| | - Toshinori Yoshida
- Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan
| | - Makoto Shibutani
- Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan.
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Wang Y, Wang Y, Dong J, Wei W, Song B, Min H, Yu Y, Lei X, Zhao M, Teng W, Chen J. Developmental hypothyroxinemia and hypothyroidism reduce proliferation of cerebellar granule neuron precursors in rat offspring by downregulation of the sonic hedgehog signaling pathway. Mol Neurobiol 2013; 49:1143-52. [PMID: 24264724 DOI: 10.1007/s12035-013-8587-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Accepted: 11/05/2013] [Indexed: 01/19/2023]
Abstract
Iodine deficiency (ID)-induced hypothyroxinemia and hypothyroidism during development result in dysfunction of the central nervous system, affecting psychomotor and motor function, although the underlying mechanisms causing these alterations are still unclear. Therefore, our aim is to study the effects of developmental hypothyroxinemia, caused by mild ID, and developmental hypothyroidism, caused by severe ID or methimazole (MMZ), on the proliferation of cerebellar granule neuron precursors (CGNPs), an excellent experimental model of cerebellar development and function. The sonic hedgehog (Shh) signaling pathway is essential for CGNP proliferation, and as such, its activation is also investigated here. A maternal hypothyroxinemia model was established in Wistar rats by administrating a mild ID diet, and two maternal hypothyroidism models were developed either by administrating a severe ID diet or MMZ water. Our results showed that hypothyroxinemia and hypothyroidism reduced proliferation of CGNPs on postnatal day (PN) 7, PN14, and PN21. Accordingly, the mean intensity of proliferating cell nuclear antigen and Ki67 nuclear antigen immunofluorescence was reduced in the mild ID, severe ID, and MMZ groups. Moreover, maternal hypothyroxinemia and hypothyroidism reduced expression of the Shh signaling pathway on PN7, PN14, and PN21. Our study supports the hypothesis that developmental hypothyroxinemia induced by mild ID, and hypothyroidism induced by severe ID or MMZ, reduce the proliferation of CGNPs, which may be ascribed to the downregulation of the Shh signaling pathway.
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Affiliation(s)
- Yuan Wang
- Department of Occupational and Environmental Health, School of Public Health, China Medical University, 92 North 2nd Road, Shenyang, 110001, People's Republic of China
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Paul KB, Hedge JM, Macherla C, Filer DL, Burgess E, Simmons SO, Crofton KM, Hornung MW. Cross-species analysis of thyroperoxidase inhibition by xenobiotics demonstrates conservation of response between pig and rat. Toxicology 2013; 312:97-107. [DOI: 10.1016/j.tox.2013.08.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 08/02/2013] [Accepted: 08/09/2013] [Indexed: 10/26/2022]
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Axelstad M, Boberg J, Vinggaard AM, Christiansen S, Hass U. Triclosan exposure reduces thyroxine levels in pregnant and lactating rat dams and in directly exposed offspring. Food Chem Toxicol 2013; 59:534-40. [PMID: 23831729 DOI: 10.1016/j.fct.2013.06.050] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 06/24/2013] [Accepted: 06/25/2013] [Indexed: 01/23/2023]
Abstract
Thyroid disrupting chemicals can potentially disrupt brain development. Two studies investigating the effect of the antibacterial compound triclosan on thyroxine (T₄) levels in rats are reported. In the first, Wistar rat dams were gavaged with 75, 150 or 300 mg triclosan/kg bw/day throughout gestation and lactation. Total T₄ serum levels were measured in dams and offspring, and all doses of triclosan significantly lowered T₄ in dams, but no significant effects on T₄ levels were seen in the offspring at the end of the lactation period. Since this lack of effect could be due to minimal exposure through maternal milk, a second study using direct per oral pup exposure from postnatal day 3-16 to 50 or 150 mg triclosan/kg bw/day was performed. This exposure pointed to significant T₄ reductions in 16 day old offspring in both dose groups. These results corroborate previous studies showing that in rats lactational transfer of triclosan seems limited. Since an optimal study design for testing potential developmental neurotoxicants in rats, should include exposure during both the pre- and postnatal periods of brain development, we suggest that in the case of triclosan, direct dosing of pups may be the best way to obtain that goal.
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Affiliation(s)
- Marta Axelstad
- National Food Institute, Technical University of Denmark, Division of Toxicology and Risk Assessment, Søborg, Denmark.
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Wang Y, Wei W, Wang Y, Dong J, Song B, Min H, Teng W, Chen J. Neurotoxicity of developmental hypothyroxinemia and hypothyroidism in rats: Impairments of long-term potentiation are mediated by phosphatidylinositol 3-kinase signaling pathway. Toxicol Appl Pharmacol 2013; 271:257-65. [PMID: 23707767 DOI: 10.1016/j.taap.2013.04.034] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 04/24/2013] [Accepted: 04/29/2013] [Indexed: 12/15/2022]
Abstract
Neurotoxicity of iodine deficiency-induced hypothyroidism during developmental period results in serious impairments of brain function, such as learning and memory. These impairments are largely irreversible, and the underlying mechanisms remain unclear. In addition to hypothyroidism, iodine deficiency may cause hypothyroxinemia, a relatively subtle form of thyroid hormone deficiency. Neurotoxicity of developmental hypothyroxinemia also potentially impairs learning and memory. However, more direct evidence of the associations between developmental hypothyroxinemia and impairments of learning and memory should be provided, and the underlying mechanisms remain to be elucidated. Thus, in the present study, we investigated the effects of developmental hypothyroxinemia and hypothyroidism on long-term potentiation (LTP), a widely accepted cellular model of learning and memory, in the hippocampal CA1 region. The activation of the phosphatidylinositol 3-kinase (PI3K) signaling pathway - a pathway closely associated with synaptic plasticity and learning and memory - was also investigated. Wistar rats were treated with iodine deficient diet or methimazole (MMZ) to induce developmental hypothyroxinemia or hypothyroidism. The results showed that developmental hypothyroxinemia caused by mild iodine deficiency and developmental hypothyroidism caused by severe iodine deficiency or MMZ significantly reduced the field-excitatory postsynaptic potential (f-EPSP) slope and the population spike (PS) amplitude. Decreased activation of the PI3K signaling pathway was also observed in rats subjected to developmental hypothyroxinemia or hypothyroidism. Our results may support the hypothesis that neurotoxicity of both developmental hypothyroxinemia and hypothyroidism causes damages to learning and memory. Our results also suggest that decreased activation of the PI3K signaling pathway may contribute to impairments of LTP caused by neurotoxicity of both developmental hypothyroxinemia and hypothyroidism.
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Affiliation(s)
- Yi Wang
- Department of Occupational and Environmental Health, School of Public Health, China Medical University, Shenyang, PR China
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Boone MD, Hammond SA, Veldhoen N, Youngquist M, Helbing CC. Specific time of exposure during tadpole development influences biological effects of the insecticide carbaryl in green frogs (Lithobates clamitans). AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2013; 130-131:139-148. [PMID: 23399446 DOI: 10.1016/j.aquatox.2012.12.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2012] [Revised: 12/21/2012] [Accepted: 12/22/2012] [Indexed: 06/01/2023]
Abstract
The orchestration of anuran metamorphosis is initiated and integrated by thyroid hormones, which change dynamically during larval development and which may represent a target of disruption by environmental contaminants. Studies have found that some anurans experience increased rates of development when exposed to the insecticide carbaryl later in larval development, suggesting that this insecticide could affect thyroid hormone-associated biological pathways. However, the time in development when tadpoles are sensitive to insecticide exposure has not been clearly defined nor has the mechanism been tested. In two separate studies, we exposed recently hatched green frog (Lithobates clamitans) tadpoles to a single, three day carbaryl exposure in the laboratory at either 2, 4, 8, or 16 weeks post-hatching. We examined the impact of carbaryl exposure on mRNA abundance patterns in the brains of frogs following metamorphosis months after a single three day exposure (experiment 1) and in tadpole tails three days after exposure (experiment 2) using cDNA microarrays and quantitative real time polymerase chain reaction (QPCR) analyses. For tadpoles reared through metamorphosis, we measured tadpole growth and development, as well as time to, mass at, and survival to metamorphosis. Although carbaryl did not significantly impact tadpole development, metamorphosis, or survival, clear exposure-related alterations in both tail and brain transcript levels were evident when tadpoles were exposed to carbaryl, particularly in tadpoles exposed at weeks 8 and 16 post-hatching, indicating both short-term and long-term alterations in mRNA expression. These results indicate that carbaryl can have long-lasting effects on brain development when exposure occurs at sensitive developmental stages, which may have implications for animal fitness and function later in the life cycle.
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Wada H, Yumoto S, Iso H. Irreversible damage to auditory system functions caused by perinatal hypothyroidism in rats. Neurotoxicol Teratol 2013; 37:18-22. [PMID: 23422508 DOI: 10.1016/j.ntt.2013.02.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 02/07/2013] [Accepted: 02/08/2013] [Indexed: 11/18/2022]
Abstract
We examined the effect of perinatal hypothyroidism on auditory function in rats using a prepulse inhibition paradigm. Pregnant rats were treated with the antithyroid drug methimazole (1-methyl-2-mercaptoimidazole) from gestational day 15 to postnatal day 21 via drinking water at concentrations (w/v) of 0 (control), 0.002 (low dose), or 0.02% (high dose). Rats from methimazole-treated mothers were tested at ages 1, 6, and 12months using techniques to examine prepulse inhibition and startle response. The startle stimulus consisted of 40ms of white noise at 115dB, whereas the prepulse, which preceded the startle stimulus by 30ms, consisted of 20ms of white noise at 75, 85, or 95dB. When the prepulse intensity was 75 or 85dB, the high-dose group showed decreased prepulse inhibition percentages compared with the control and low-dose groups. The reduced percentages of prepulse inhibition did not return to control levels over the 12-month study period. In contrast, no differences in prepulse inhibition were observed among the three dose groups when prepulse intensity was 95dB. Moreover, the high-dose group displayed excessive reaction to auditory startle stimuli compared with the other groups. Reductions in plasma free thyroxine and body weight gain were observed in the high-dose group. We conclude that perinatal hypothyroidism results in irreversible damage to auditory function in rats.
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Affiliation(s)
- Hiromi Wada
- Graduate School of Letters, Hokkaido University, Kita 10 Nishi 7 Kita-Ku, Sapporo, Japan.
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Selderslaghs IWT, Hooyberghs J, Blust R, Witters HE. Assessment of the developmental neurotoxicity of compounds by measuring locomotor activity in zebrafish embryos and larvae. Neurotoxicol Teratol 2013; 37:44-56. [PMID: 23357511 DOI: 10.1016/j.ntt.2013.01.003] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 01/17/2013] [Accepted: 01/17/2013] [Indexed: 12/27/2022]
Abstract
The developmental neurotoxic potential of the majority of environmental chemicals and drugs is currently undetermined. Specific in vivo studies provide useful data for hazard assessment but are not amenable to screen thousands of untested compounds. In this study, methods which use zebrafish embryos, eleutheroembryos and larvae as model organisms, were proposed as alternatives for developmental neurotoxicity (DNT) testing. The evaluation of spontaneous tail coilings in zebrafish embryos aged 24-26 hours post fertilization (hpf) and the swimming activity of eleutheroembryos at 120 and larvae at 144 hpf, i.e. parameters for locomotor activity, were investigated as potential endpoints for DNT testing, according to available standard protocols. The overall performance and predictive value of these methods was then examined by testing a training set of 10 compounds, including known developmental neurotoxicants and compounds not considered to be neurotoxic. The classification of the selected compounds as either neurotoxic or non-neurotoxic, based on the effects observed in zebrafish embryos and larvae, was compared to available mammalian data and an overall concordance of 90% was achieved. Furthermore, the specificity of the selected endpoints for DNT was evaluated as well as the potential similarities between zebrafish and mammals with regard to mechanisms of action for the selected compounds. Although further studies, including the screening of a large testing set of compounds are required, we suggest that the proposed methods with zebrafish embryos and larvae might be valuable alternatives for animal testing for the screening and prioritization of compounds for DNT.
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Affiliation(s)
- Ingrid W T Selderslaghs
- VITO NV, Flemish Institute for Technological Research, Environmental Risk and Health, Boeretang 200, Mol, Belgium.
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Gilbert ME, Hedge JM, Valentín-Blasini L, Blount BC, Kannan K, Tietge J, Zoeller RT, Crofton KM, Jarrett JM, Fisher JW. An Animal Model of Marginal Iodine Deficiency During Development: The Thyroid Axis and Neurodevelopmental Outcome*. Toxicol Sci 2013; 132:177-95. [DOI: 10.1093/toxsci/kfs335] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Gilbert ME, Lasley SM. Developmental thyroid hormone insufficiency and brain development: a role for brain-derived neurotrophic factor (BDNF)? Neuroscience 2012. [PMID: 23201250 DOI: 10.1016/j.neuroscience.2012.11.022] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Thyroid hormones (TH) are essential for normal brain development. Even modest degrees of TH disruption experienced in utero can result in neuropsychological deficits in children despite normal thyroid status at birth. Neurotrophins have been implicated in a host of brain cellular functions, and in particular, brain-derived neurotrophic factor (BDNF) has a well documented role in development and function of the nervous system. A number of laboratories have reported the effects of TH administration or severe deprivation on neurotrophin expression in brain. This review provides an overview and update of recent developments in the thyroid field as they relate to the nervous system. Secondly, we describe an animal model of low level TH insufficiency that is more relevant for studying the neurological consequences associated with the modest TH perturbations of subclinical hypothyroidism, or that would be anticipated from exposure to environmental contaminants with a mode-of-action that involves the thyroid. Finally, we review the available in vivo literature on TH-mediated alterations in neurotrophins, particularly BDNF, and discuss their possible contribution to brain impairments associated with TH insufficiency. The observations of altered BDNF protein and gene expression have varied as a function of hypothyroid model, age, and brain region assessed. Only a handful of studies have investigated the relationship of neurotrophins and TH using models of TH deprivation that are not severe, and dose-response information is sparse. Differences in the models used, species, doses, regions assessed, age at assessment, and method employed make it difficult to reach a consensus. Based on the available literature, the case for a direct role for BDNF in thyroid-mediated effects in the brain is not compelling. We conclude that delineation of the potential role of neurotrophins in TH-mediated neuronal development may be more fruitful by examining additional neurotrophins (e.g., nerve growth factor), moderate degrees of TH insufficiency, and younger ages. We further suggest that investigation of BDNF invoked by synaptic activation (i.e., plasticity, enrichment, trauma) may serve to elucidate a role of thyroid hormone in BDNF-regulated synaptic function.
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Affiliation(s)
- M E Gilbert
- Toxicity Assessment Division, Neurotoxicology Branch, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA.
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