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Daviduck Q, North S, Swaleh R. Hypothyroïdie causée par l’apalutamide. CMAJ 2024; 196:E242. [PMID: 38408780 PMCID: PMC10896598 DOI: 10.1503/cmaj.230555-f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2024] Open
Affiliation(s)
- Quinn Daviduck
- Départements de médecine interne générale (Daviduck), d'oncologie (North) et d'endocrinologie (Swaleh), Université de l'Alberta, Edmonton, Alb
| | - Scott North
- Départements de médecine interne générale (Daviduck), d'oncologie (North) et d'endocrinologie (Swaleh), Université de l'Alberta, Edmonton, Alb
| | - Rukia Swaleh
- Départements de médecine interne générale (Daviduck), d'oncologie (North) et d'endocrinologie (Swaleh), Université de l'Alberta, Edmonton, Alb.
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2
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Daviduck Q, North S, Swaleh R. Hypothyroidism caused by apalutamide. CMAJ 2023; 195:E1443. [PMID: 37903525 PMCID: PMC10615340 DOI: 10.1503/cmaj.230555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2023] Open
Affiliation(s)
- Quinn Daviduck
- Departments of General Internal Medicine (Daviduck), Oncology (North) and Endocrinology (Swaleh), University of Alberta, Edmonton, Alta
| | - Scott North
- Departments of General Internal Medicine (Daviduck), Oncology (North) and Endocrinology (Swaleh), University of Alberta, Edmonton, Alta
| | - Rukia Swaleh
- Departments of General Internal Medicine (Daviduck), Oncology (North) and Endocrinology (Swaleh), University of Alberta, Edmonton, Alta.
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3
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Eytcheson SA, Olker JH, Friedman KP, Hornung MW, Degitz SJ. Assessing utility of thyroid in vitro screening assays through comparisons to observed impacts in vivo. Regul Toxicol Pharmacol 2023; 144:105491. [PMID: 37666444 DOI: 10.1016/j.yrtph.2023.105491] [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: 01/05/2023] [Revised: 08/22/2023] [Accepted: 08/30/2023] [Indexed: 09/06/2023]
Abstract
To better understand endocrine disruption, the U.S. Environmental Protection Agency's (USEPA) Endocrine Disruptor Screening Program (EDSP) utilizes a two-tiered approach to investigate the potential of a chemical to interact with the estrogen, androgen, or thyroid systems. As in vivo testing lacks the throughput to address data gaps on endocrine bioactivity for thousands of chemicals, in vitro high-throughput screening (HTS) methods are being developed to screen larger chemical libraries. The primary objective of this work was to investigate for how many of the 52 chemicals with weight-of-evidence (WoE) determinations from EDSP Tier 1 screening there are available in vitro HTS data supporting a thyroid impact. HTS data from the USEPA ToxCast program and the EDSP WoE were collected for this analysis. Considering the complexity of endocrine disruption and interpreting HTS data, concordance between in vitro activity and in vivo effects ranges from 58 to 78%. Based on this evaluation, we conclude that the current suite of HTS assays is beneficial for prioritizing chemicals for further inquiry; however, without a more detailed analysis, one cannot conclude whether HTS results are the primary mode-of-action. Furthermore, development of in vitro assays for additional thyroid-relevant molecular initiating events is required to effectively predict in vivo thyroid impacts.
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Affiliation(s)
- Stephanie A Eytcheson
- Oak Ridge Institute for Science and Education, Oak Ridge, TN, USA; U.S. Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Great Lakes Toxicology and Ecology Division, Duluth, MN, 55804, USA
| | - Jennifer H Olker
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Great Lakes Toxicology and Ecology Division, Duluth, MN, 55804, USA
| | - Katie Paul Friedman
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Biomolecular and Computational Toxicology Division, Research Triangle Park, NC, 27711, USA
| | - Michael W Hornung
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Great Lakes Toxicology and Ecology Division, Duluth, MN, 55804, USA
| | - Sigmund J Degitz
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Great Lakes Toxicology and Ecology Division, Duluth, MN, 55804, USA.
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4
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Tallon MJ, Child R. Subchronic oral toxicity assessment of a cannabis extract. Regul Toxicol Pharmacol 2023; 144:105496. [PMID: 37734651 DOI: 10.1016/j.yrtph.2023.105496] [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: 03/31/2023] [Revised: 09/10/2023] [Accepted: 09/13/2023] [Indexed: 09/23/2023]
Abstract
Cannabidiol (CBD) is present in Cannabis Sativa L. and has been used in medicines and foods to deliver beneficial health effects. Despite this, research on CBD safety utilising modern testing methods is lacking. Therefore three separate safety experiments were performed on a CBD isolate. Sprague-Dawley rats were used to investigate prenatal development, a 14-day toxicity sighting study, and an OECD compliant 90-day subchronic oral toxicity trial, with 35-day off-dose recovery. The prenatal screening study demonstrated reduced body weights and food consumption in the highest dose group, but no substance-related changes in pregnancy rate, maternal or placental gross abnormalities, or premature deliveries. The 14-day study indicated tolerance up to 460 mg/kg bw/d of CBD isolate. Based on these findings, a 90-day repeated dose oral toxicity study was performed at doses of 0, 30, 115, 230, and 460 mg/kg bw/d of CBD, followed by a 35-day off-dose recovery period. In the 90-day study, some non-adverse organ and tissue changes were observed. With the exception of the high dose group, these fully reversed during the recovery period. Based on these findings, sub-chronic consumption of highly purified isolate results in a CBD NOAEL of 460 mg/kg bw/d for males and 230 mg/kg bw/d for females.
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Affiliation(s)
- Mark J Tallon
- Legal Products Group Ltd, 26 St Thomas Pl, Ely, Cambridgeshire, CB7 4EX, UK.
| | - Robert Child
- Legal Products Group Ltd, 26 St Thomas Pl, Ely, Cambridgeshire, CB7 4EX, UK; School of Chemical Engineering, University of Birmingham, Birmingham, B15 2TT, UK
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5
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Wagner VA, Holl KL, Clark KC, Reho JJ, Dwinell MR, Lehmler HJ, Raff H, Grobe JL, Kwitek AE. Genetic background in the rat affects endocrine and metabolic outcomes of bisphenol F exposure. Toxicol Sci 2023; 194:84-100. [PMID: 37191987 PMCID: PMC10306406 DOI: 10.1093/toxsci/kfad046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023] Open
Abstract
Environmental bisphenol compounds like bisphenol F (BPF) are endocrine-disrupting chemicals (EDCs) affecting adipose and classical endocrine systems. Genetic factors that influence EDC exposure outcomes are poorly understood and are unaccounted variables that may contribute to the large range of reported outcomes in the human population. We previously demonstrated that BPF exposure increased body growth and adiposity in male N/NIH heterogeneous stock (HS) rats, a genetically heterogeneous outbred population. We hypothesize that the founder strains of the HS rat exhibit EDC effects that were strain- and sex-dependent. Weanling littermate pairs of male and female ACI, BN, BUF, F344, M520, and WKY rats randomly received either vehicle (0.1% EtOH) or 1.125 mg BPF/l in 0.1% EtOH for 10 weeks in drinking water. Body weight and fluid intake were measured weekly, metabolic parameters were assessed, and blood and tissues were collected. BPF increased thyroid weight in ACI males, thymus and kidney weight in BUF females, adrenal weight in WKY males, and possibly increased pituitary weight in BN males. BUF females also developed a disruption in activity and metabolic rate with BPF exposure. These sex- and strain-specific exposure outcomes illustrate that HS rat founders possess diverse bisphenol-exposure risk alleles and suggest that BPF exposure may intensify inherent organ system dysfunction existing in the HS rat founders. We propose that the HS rat will be an invaluable model for dissecting gene EDC interactions on health.
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Affiliation(s)
- Valerie A Wagner
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
| | - Katie L Holl
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
| | - Karen C Clark
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
- Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
| | - John J Reho
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
- Comprehensive Rodent Metabolic Phenotyping Core, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
| | - Melinda R Dwinell
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
- Rat Genome Database, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
| | - Hans-Joachim Lehmler
- Department of Occupational and Environmental Health, University of Iowa, Iowa City, Iowa 52246, USA
| | - Hershel Raff
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
- Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
- Endocrine Research Laboratory, Aurora St. Luke’s Medical Center, Advocate Aurora Research Institute, Milwaukee, Wisconsin 53233, USA
| | - Justin L Grobe
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
- Comprehensive Rodent Metabolic Phenotyping Core, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
| | - Anne E Kwitek
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
- Rat Genome Database, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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6
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Zhou J, De Jonghe S, Codd EE, Weiner S, Gallacher D, Stahle P, Kelley MF, Kuffner EK, Flores CM, Eichenbaum GE. Preclinical safety assessment of JNJ-10450232 (NTM-006), a structural analog of acetaminophen, that does not cause hepatotoxicity at supratherapeutic doses. Regul Toxicol Pharmacol 2023:105334. [PMID: 36608923 DOI: 10.1016/j.yrtph.2023.105334] [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: 08/01/2022] [Revised: 12/05/2022] [Accepted: 01/03/2023] [Indexed: 01/05/2023]
Abstract
JNJ-10450232 (NTM-006) is a new molecular entity that is structurally related to acetaminophen. A comprehensive non-clinical safety program was conducted to support first-in-human and clinical efficacy studies based on preclinical data suggesting that the compound has comparable or enhanced antinociceptive and antipyretic efficacy without causing hepatotoxicity at supratherapeutic doses. No hepatic toxicity was noted in a mouse model sensitive to acetaminophen hepatotoxicity or in rats, dogs, and non-human primates in 28-day repeat dose toxicity studies at and above doses/exposures at which acetaminophen is known to cause hepatotoxicity. In the 28-day toxicity studies, all treatment-related findings were monitorable and reversible. Methemoglobinemia, which was observed in dogs and to a lesser extent in rats, is also observed with acetaminophen. This finding is considered not relevant to humans due to species differences in metabolism. Thyroid hypertrophy and hyperplasia were also observed in dogs and were shown to be a consequence of a species-specific UGT induction also demonstrated with increased thyroid hormone metabolism. Indirect bilirubin elevation was observed in rats as a result of UGT1A1 Inhibition. JNJ-10450232 (NTM-006) had no toxicologically relevant findings in safety pharmacology or genotoxicity studies. Together, these data supported progressing into safety and efficacy studies in humans.
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Affiliation(s)
- Junguo Zhou
- Janssen Research & Development, LLC, Raritan, NJ, USA
| | - Sandra De Jonghe
- Janssen Research & Development, A Division of Janssen Pharmaceutica NV, Beerse, Belgium
| | - Ellen E Codd
- Janssen Research & Development, LLC, Raritan, NJ, USA
| | - Sandy Weiner
- Janssen Research & Development, LLC, Spring House, PA, USA
| | - David Gallacher
- Janssen Research & Development, A Division of Janssen Pharmaceutica NV, Beerse, Belgium
| | - Paul Stahle
- Janssen Research & Development, LLC, Spring House, PA, USA
| | | | - Edwin K Kuffner
- Johnson & Johnson Consumer Companies, Fort Washington, PA, USA.
| | | | - Gary E Eichenbaum
- Office of the Chief Medical Officer, Johnson & Johnson, New Brunswick, NJ, USA
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7
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Ishikawa A, Yamanouchi S, Iwasaki W, Kitano J. Convergent copy number increase of genes associated with freshwater colonization in fishes. Philos Trans R Soc Lond B Biol Sci 2022; 377:20200509. [PMID: 35634928 PMCID: PMC9149799 DOI: 10.1098/rstb.2020.0509] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 03/14/2022] [Indexed: 07/20/2023] Open
Abstract
Copy number variation (CNV) can cause phenotypic changes. However, in contrast to amino acid substitutions and cis-regulatory changes, little is known about the functional categories of genes in which CNV is important for adaptation to novel environments. It is also unclear whether the same genes repeatedly change the copy numbers for adapting to similar environments. Here, we investigate CNV associated with freshwater colonization in fishes, which was observed multiple times across different lineages. Using 48 ray-finned fishes across diverse orders, we identified 23 genes whose copy number increases were associated with freshwater colonization. These genes showed enrichment for peptide receptor activity, hexosyltransferase activity and unsaturated fatty acid metabolism. We further revealed that three of the genes showed copy number increases in freshwater populations compared to marine ancestral populations of the stickleback genus Gasterosteus. These results indicate that copy number increases of genes involved in fatty acid metabolism (FADS2), immune function (PSMB8a) and thyroid hormone metabolism (UGT2) may be important for freshwater colonization at both the inter-order macroevolutionary scale and at the intra-genus microevolutionary scale. Further analysis across diverse taxa will help to understand the role of CNV in the adaptation to novel environments. This article is part of the theme issue 'Genetic basis of adaptation and speciation: from loci to causative mutations'.
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Affiliation(s)
- Asano Ishikawa
- Ecological Genetics Laboratory, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan
| | - Shun Yamanouchi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Wataru Iwasaki
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Jun Kitano
- Ecological Genetics Laboratory, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan
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8
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Vansell NR. Mechanisms by Which Inducers of Drug Metabolizing Enzymes Alter Thyroid Hormones in Rats. Drug Metab Dispos 2022; 50:508-517. [DOI: 10.1124/dmd.121.000498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 12/23/2021] [Indexed: 11/22/2022] Open
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9
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Yamauchi H, Andou T, Watanabe T, Gotou M, Anayama H. Quantitative protein profiling of phenobarbital-induced drug metabolizing enzymes in rat liver by liquid chromatography mass spectrometry using formalin-fixed paraffin-embedded samples. J Pharmacol Toxicol Methods 2021; 112:107107. [PMID: 34363961 DOI: 10.1016/j.vascn.2021.107107] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 07/21/2021] [Accepted: 08/01/2021] [Indexed: 10/20/2022]
Abstract
Administration of a compound can induce drug-metabolizing enzymes (DMEs) in the liver. DME induction can affect various parameters in toxicology studies. Therefore, evaluation of DME induction is important for interpreting test compound-induced biological responses. Several methods such as measurement of hepatic microsomal DME activity using substrates, electron microscopy, or immunohistochemistry have been used; however, these methods are limited in throughput and specificity or are not quantitative. Liquid chromatography mass spectrometry (LC/MS)-based protein analysis can detect and quantify multiple proteins simultaneously per assay. Studies have shown that formalin-fixed paraffin-embedded (FFPE) samples, which are routinely collected in toxicology studies, can be used for LC/MS-based protein analysis. To validate the utility of LC/MS using FFPE samples for quantitative evaluation of DME induction, we treated rats with a DME inducer, phenobarbital, and compared the protein expression levels of 13 phase-I and 11 phase-II DMEs between FFPE and fresh frozen hepatic samples using LC/MS. A good correlation between data from FFPE and frozen samples was obtained after analysis. In FFPE and frozen samples, the expression of 6 phase-I and 8 phase-II DMEs showed a similar significant increase and a prominent rise in Cyp2b2 and Cyp3a1 levels. In addition, LC/MS data were consistent with the measurement of microsomal DME activities. These results suggest that LC/MS-based protein expression analysis using FFPE samples is as effective as that using frozen samples for detecting DME induction.
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Affiliation(s)
- Hirofumi Yamauchi
- Drug Safety Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan.
| | - Tomohiro Andou
- Integrated Technology Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Takeshi Watanabe
- Drug Safety Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Masamitsu Gotou
- Integrated Technology Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Hisashi Anayama
- Drug Safety Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1 Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
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10
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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: 40] [Impact Index Per Article: 10.0] [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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11
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Cook I, Asenjo AB, Sosa H, Leyh TS. The Human UGT2B7 Nanodisc. Drug Metab Dispos 2019; 48:198-204. [PMID: 31892527 DOI: 10.1124/dmd.119.089946] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 12/30/2019] [Indexed: 01/01/2023] Open
Abstract
The 20 uridine diphosphate glycosyl-transferases (UGTs) encoded in the human genome form an essential homeostatic network of overlapping catalytic functions that surveil and regulate the activity and clearance of scores of small molecule metabolites. Biochemical and biophysical UGT studies have been hampered by the inability to purify these membrane-bound proteins. Here, using cell-free expression and nanodisc technology, we assemble and purify to homogeneity the first UGT nanodisc-the human UGT2B7•nanodisc. The complex is readily isolated in milligram quantities. It is stable and its initial-rate parameters are identical within error to those associated with UGT2B7 in microsomal preparations (i.e., Supersomes). The high purity of the nanodisc preparation simplifies UGT assays, which allows complexities traditionally associated with microsomal assays (latency and the albumin effect) to be circumvented. Each nanodisc is shown to harbor a single UGT2B7 monomer. The methods described herein should be widely applicable to UGTs, and these findings are expected to set the stage for experimentalists to more freely explore the structure, function, and biology of this important area of phase II metabolism. SIGNIFICANCE STATEMENT: Lack of access to pure, catalytically competent human uridine diphosphate glucuronosyl-transferases (UGTs) has long been an impediment to biochemical and biophysical studies of this disease-relevant enzyme family. Here, we demonstrate this barrier can be removed using nanodisc technology-a human UGT2B7•nanodisc is assembled, purified to homogeneity, and shown to have activity comparable to microsomal UGT2B7.
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Affiliation(s)
- Ian Cook
- Departments of Microbiology and Immunology (I.C., T.S.L.) and Physiology and Biophysics (A.B.A., H.S.), Albert Einstein College of Medicine, New York City, New York
| | - Anna B Asenjo
- Departments of Microbiology and Immunology (I.C., T.S.L.) and Physiology and Biophysics (A.B.A., H.S.), Albert Einstein College of Medicine, New York City, New York
| | - Hernando Sosa
- Departments of Microbiology and Immunology (I.C., T.S.L.) and Physiology and Biophysics (A.B.A., H.S.), Albert Einstein College of Medicine, New York City, New York
| | - Thomas S Leyh
- Departments of Microbiology and Immunology (I.C., T.S.L.) and Physiology and Biophysics (A.B.A., H.S.), Albert Einstein College of Medicine, New York City, New York
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12
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Kutsukake T, Furukawa Y, Ondo K, Gotoh S, Fukami T, Nakajima M. Quantitative Analysis of UDP-Glucuronosyltransferase Ugt1a and Ugt2b mRNA Expression in the Rat Liver and Small Intestine: Sex and Strain Differences. Drug Metab Dispos 2018; 47:38-44. [DOI: 10.1124/dmd.118.083287] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 10/29/2018] [Indexed: 11/22/2022] Open
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13
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Tsubokura Y, Hasegawa R, Aso S, Kobayashi T, Koga T, Hoshuyama S, Oshima Y, Miyata K, Kusune Y, Muroi T, Hashizume N, Inoue Y, Ajimi S, Furukawa K. Combined repeated-dose and reproductive/developmental toxicity screening test of benzene, 1,1'-oxybis-, tetrapropylene derivs. in rats. Drug Chem Toxicol 2017; 41:492-500. [PMID: 29156995 DOI: 10.1080/01480545.2017.1397161] [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: 10/18/2022]
Abstract
We have conducted animal toxicity tests of chemicals for a chemical safety program implemented by the Ministry of Economy, Trade and Industry of Japan. Here we conducted a combined repeated-dose and reproductive/developmental toxicity screening test of benzene, 1,1'-oxybis-, tetrapropylene derivs. (BOTD). BOTD was administered to 9-week-old Crl:CD(SD) male and female rats by gavage at 0, 40, 200, or 1000 mg/kg/day. Males were treated for 42 days including mating period. Females were treated for 42-53 days through the premating, mating, pregnancy, and until Day 4 of lactation periods. Increases in prothrombin time and activated partial thromboplastin time values were observed only in males at 200 and 1000 mg/kg/day. Hypertrophy of centrilobular hepatocytes was observed with increased liver weight in both sexes at 200 and 1000 mg/kg/day, but there was no histologic evidence of hepatotoxicity. Diffuse hypertrophy of follicular cells in thyroid glands was observed in females at 200 mg/kg/day and in both sexes at 1000 mg/kg/day, with an increased blood cholesterol level in females at 1000 mg/kg/day. The conception index was decreased for females at 1000 mg/kg/day; and no abnormalities were detected in the reproductive indices of implantation, delivery, or pups' condition, although a slight increase in the pups' body weight was noted at birth. Our data indicate a no-observed-adverse-effect level of 40 mg/kg/day for repeated-dose toxicity on the basis of the prolongation of blood coagulating time, and of 200 mg/kg/day for reproductive/developmental toxicity on the basis of the decreased conception index.
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Affiliation(s)
- Yasuhiro Tsubokura
- a CERI Hita , Chemicals Evaluation and Research Institute, Japan , Hita-shi , Oita , Japan
| | - Ryuichi Hasegawa
- b Chemical Biotesting Center , Chemicals Evaluation and Research Institute, Japan , Tokyo , Japan
| | - Sunao Aso
- a CERI Hita , Chemicals Evaluation and Research Institute, Japan , Hita-shi , Oita , Japan
| | - Toshio Kobayashi
- a CERI Hita , Chemicals Evaluation and Research Institute, Japan , Hita-shi , Oita , Japan
| | - Takayuki Koga
- a CERI Hita , Chemicals Evaluation and Research Institute, Japan , Hita-shi , Oita , Japan
| | - Satsuki Hoshuyama
- a CERI Hita , Chemicals Evaluation and Research Institute, Japan , Hita-shi , Oita , Japan
| | - Yutaka Oshima
- a CERI Hita , Chemicals Evaluation and Research Institute, Japan , Hita-shi , Oita , Japan
| | - Katsumi Miyata
- a CERI Hita , Chemicals Evaluation and Research Institute, Japan , Hita-shi , Oita , Japan
| | - Yuji Kusune
- a CERI Hita , Chemicals Evaluation and Research Institute, Japan , Hita-shi , Oita , Japan
| | - Takako Muroi
- a CERI Hita , Chemicals Evaluation and Research Institute, Japan , Hita-shi , Oita , Japan
| | - Naoki Hashizume
- c CERI Kurume , Chemicals Evaluation and Research Institute, Japan , Kurume-shi , Fukuoka , Japan
| | - Yoshiyuki Inoue
- c CERI Kurume , Chemicals Evaluation and Research Institute, Japan , Kurume-shi , Fukuoka , Japan
| | - Shozo Ajimi
- a CERI Hita , Chemicals Evaluation and Research Institute, Japan , Hita-shi , Oita , Japan
| | - Kotaro Furukawa
- a CERI Hita , Chemicals Evaluation and Research Institute, Japan , Hita-shi , Oita , Japan
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14
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Tsubokura Y, Hasegawa R, Aso S, Kobayashi T, Koga T, Hoshuyama S, Oshima Y, Miyata K, Kusune Y, Muroi T, Hashizume N, Inoue Y, Ajimi S, Furukawa K. Combined repeated-dose and reproductive/developmental toxicity screening test of 1-tert-butoxy-4-chlorobenzene in rats. Drug Chem Toxicol 2016; 40:344-358. [PMID: 27790921 DOI: 10.1080/01480545.2016.1236265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
We have carried out animal toxicity tests of chemicals for a chemical safety program implemented by the Ministry of Economy, Trade, and Industry of Japan. Here, we tested 1-tert-butoxy-4-chlorobenzene in a combined repeat-dose and developmental and reproductive toxicity test. The test chemical was administered daily by gavage to 9-week-old Crl:CD (SD) rats at doses of 0, 20, 100, and 500 mg/kg/d. Males were treated for 42 d beginning 14 d before mating. Females were treated from 14 d before mating to day 4 of lactation. Decreased spontaneous locomotion, decreased respiratory rate, and incomplete eyelid opening were observed at 500 mg/kg/d (both sexes), but resolved within 30 min of administration, suggesting central nervous system depression. No notable changes were observed in body weight, food consumption, functional battery tests, or blood test. Increased liver weight with centrilobular or diffuse hepatocyte hypertrophy was observed at 100 and 500 mg/kg/d (both sexes). There were no biochemical or histopathological changes related to hepatotoxicity. Increased kidney weight with basophilic tubules, tubule dilatation, and increased hyaline droplets were observed in males dosed at 100 and 500 mg/kg/d. Immunohistochemical staining indicated α2u-globulin nephropathy, a male rat-specific toxicity. Although kidney weight was also increased in females dosed at 500 mg/kg/d, it was not considered to be an adverse effect because there were no histopathological changes. Pup weights on postnatal day 0 were decreased at 500 mg/kg/d and still decreased on postnatal day 4. Our data indicated the no-observed-adverse-effect-level for repeated-dose and reproductive/developmental toxicity for 1-tert-butoxy-4-chlorobenzene was 100 mg/kg/d.
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Affiliation(s)
- Yasuhiro Tsubokura
- a CERI Hita, Chemicals Evaluation and Research Institute , Hita-shi , Oita , Japan
| | - Ryuichi Hasegawa
- b Chemical Biotesting Center, Chemicals Evaluation and Research Institute , Bunkyo-ku , Tokyo , Japan , and
| | - Sunao Aso
- a CERI Hita, Chemicals Evaluation and Research Institute , Hita-shi , Oita , Japan
| | - Toshio Kobayashi
- a CERI Hita, Chemicals Evaluation and Research Institute , Hita-shi , Oita , Japan
| | - Takayuki Koga
- a CERI Hita, Chemicals Evaluation and Research Institute , Hita-shi , Oita , Japan
| | - Satsuki Hoshuyama
- a CERI Hita, Chemicals Evaluation and Research Institute , Hita-shi , Oita , Japan
| | - Yutaka Oshima
- a CERI Hita, Chemicals Evaluation and Research Institute , Hita-shi , Oita , Japan
| | - Katsumi Miyata
- a CERI Hita, Chemicals Evaluation and Research Institute , Hita-shi , Oita , Japan
| | - Yuji Kusune
- a CERI Hita, Chemicals Evaluation and Research Institute , Hita-shi , Oita , Japan
| | - Takako Muroi
- a CERI Hita, Chemicals Evaluation and Research Institute , Hita-shi , Oita , Japan
| | - Naoki Hashizume
- c CERI Kurume, Chemicals Evaluation and Research Institute , Kurume-shi , Fukuoka , Japan
| | - Yoshiyuki Inoue
- c CERI Kurume, Chemicals Evaluation and Research Institute , Kurume-shi , Fukuoka , Japan
| | - Shozo Ajimi
- a CERI Hita, Chemicals Evaluation and Research Institute , Hita-shi , Oita , Japan
| | - Kotaro Furukawa
- a CERI Hita, Chemicals Evaluation and Research Institute , Hita-shi , Oita , Japan
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15
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Técher R, Houde M, Verreault J. Associations between organohalogen concentrations and transcription of thyroid-related genes in a highly contaminated gull population. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 545-546:289-298. [PMID: 26747993 DOI: 10.1016/j.scitotenv.2015.12.110] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 12/22/2015] [Accepted: 12/22/2015] [Indexed: 06/05/2023]
Abstract
A number of studies have reported altered circulating thyroid hormone levels in birds exposed either in controlled settings or in their natural habitat to ubiquitous organohalogen compounds including organochlorines (OCs) and polybrominated diphenyl ether (PBDE) flame retardants. However, limited attention has been paid to underlying homeostatic mechanisms in wild birds such as changes in the expression of genes in the hypothalamic-pituitary-thyroid (HPT) axis. The objective of the present study was to investigate the relationships between hepatic concentrations of major organohalogens (PBDEs and OCs), and circulating thyroid hormone (free and total thyroxine (T4) and triiodothyronine (T3)) levels and transcription of 14 thyroid-related genes in three tissues (thyroid, brain, and liver) of an urban-adapted bird exposed to high organohalogen concentrations in the Montreal area (QC, Canada), the ring-billed gull (Larus delawarensis). Positive correlations were found between liver concentrations of several polychlorinated biphenyls (PCBs), PBDEs as well as chlordanes and total plasma T4 levels. Hepatic concentrations of several PBDEs were negatively correlated with mRNA levels of deiodinase type 3, thyroid peroxidase, and thyroid hormone receptor β (TRβ) in the thyroid gland. Liver PCB (deca-CB) correlated positively with mRNA levels of sodium-iodide symporter and TRα. In brain, concentrations of most PBDEs were positively correlated with mRNA levels of organic anion transporter protein 1C1 and transthyretin, while PCBs positively correlated with expression of TRα and TRβ as well as deiodinase type 2. These multiple correlative linkages suggest that organohalogens operate through several mechanisms (direct or compensatory) involving gene transcription, thus potentially perturbing the HPT axis of this highly organohalogen-contaminated ring-billed gull population.
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Affiliation(s)
- Romy Técher
- Centre de recherche en toxicologie de l'environnement (TOXEN), Département des sciences biologiques, Université du Québec à Montréal, C.P. 8888, Succursale Centre-ville, Montreal, QC H3C 3P8, Canada.
| | - Magali Houde
- Environment Canada, St. Lawrence Centre, 105 McGill Street, Montreal, QC H2Y 2E7, Canada.
| | - Jonathan Verreault
- Centre de recherche en toxicologie de l'environnement (TOXEN), Département des sciences biologiques, Université du Québec à Montréal, C.P. 8888, Succursale Centre-ville, Montreal, QC H3C 3P8, Canada.
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16
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Tetrabromobisphenol A (TBBPA): Possible modes of action of toxicity and carcinogenicity in rodents. Food Chem Toxicol 2015; 80:206-214. [DOI: 10.1016/j.fct.2015.03.023] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 03/19/2015] [Accepted: 03/20/2015] [Indexed: 01/16/2023]
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17
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Cope RB, Kacew S, Dourson M. A reproductive, developmental and neurobehavioral study following oral exposure of tetrabromobisphenol A on Sprague-Dawley rats. Toxicology 2015; 329:49-59. [DOI: 10.1016/j.tox.2014.12.013] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 12/10/2014] [Accepted: 12/11/2014] [Indexed: 12/11/2022]
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18
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Schraplau A, Schewe B, Neuschäfer-Rube F, Ringel S, Neuber C, Kleuser B, Püschel GP. Enhanced thyroid hormone breakdown in hepatocytes by mutual induction of the constitutive androstane receptor (CAR, NR1I3) and arylhydrocarbon receptor by benzo[a]pyrene and phenobarbital. Toxicology 2015; 328:21-8. [DOI: 10.1016/j.tox.2014.12.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 12/04/2014] [Accepted: 12/05/2014] [Indexed: 12/15/2022]
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19
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Tomza-Marciniak A, Pilarczyk B, Stankiewicz T, Błaszczyk B, Kuba J. The effect of chitosan on the concentration of 17β-estradiol and free triiodothyronine in mice exposed to polychlorinated biphenyls (PCBs). JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2014; 49:376-382. [PMID: 24345235 DOI: 10.1080/10934529.2014.854568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The aim of this work was to examine (i) how the applied PCB mixture influences the level of 17β-estradiol (E2) and free triiodothyronine (FT3) in the blood plasma of mice (C57/BL/6J) and (ii) whether supplementation with chitosan would protect against the observed changes in the examined plasma hormone concentrations. In the study we used a mixture of indicator PCBs (CB no. 28, 52, 101, 118, 138, 153, 180) and our results showed their anti-estrogenic effects. Exposure to the mixture resulted in a significant decrease (P < 0.05) in plasma concentration of E2 relative to the control, and chitosan administration did not prevent the decrease. To the contrary, E2 concentration in the blood plasma of the mice which received both the PCB mixture and chitosan was lower compared to those which did not receive chitosan. Exposure to the PCBs also resulted in a decrease in FT3 concentration in the treatedgroup, although it was not as pronounced as for E2 and was prevented with dietary supplementation with chitosan, with the observed FT3 level in the chitosan-treated group similar to the control. In summary, supplementation with chitosan can only to a certain extent minimize the negative effects of exposure to PCBs.
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Affiliation(s)
- Agnieszka Tomza-Marciniak
- a Department of Animal Reproduction Biotechnology and Environmental Hygiene , West Pomeranian University of Technology, Szczecin , Poland
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20
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Malenke JR, Milash B, Miller AW, Dearing MD. Transcriptome sequencing and microarray development for the woodrat (Neotoma spp.): custom genetic tools for exploring herbivore ecology. Mol Ecol Resour 2013; 13:674-87. [PMID: 23496907 DOI: 10.1111/1755-0998.12092] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 01/31/2013] [Accepted: 02/05/2013] [Indexed: 01/08/2023]
Abstract
Massively parallel sequencing has enabled the creation of novel, in-depth genetic tools for nonmodel, ecologically important organisms. We present the de novo transcriptome sequencing, analysis and microarray development for a vertebrate herbivore, the woodrat (Neotoma spp.). This genus is of ecological and evolutionary interest, especially with respect to ingestion and hepatic metabolism of potentially toxic plant secondary compounds. We generated a liver transcriptome of the desert woodrat (Neotoma lepida) using the Roche 454 platform. The assembled contigs were well annotated using rodent references (99.7% annotation), and biotransformation function was reflected in the gene ontology. The transcriptome was used to develop a custom microarray (eArray, Agilent). We tested the microarray with three experiments: one across species with similar habitat (thus, dietary) niches, one across species with different habitat niches and one across populations within a species. The resulting one-colour arrays had high technical and biological quality. Probes designed from the woodrat transcriptome performed significantly better than functionally similar probes from the Norway rat (Rattus norvegicus). There were a multitude of expression differences across the woodrat treatments, many of which related to biotransformation processes and activities. The pattern and function of the differences indicate shared ecological pressures, and not merely phylogenetic distance, play an important role in shaping gene expression profiles of woodrat species and populations. The quality and functionality of the woodrat transcriptome and custom microarray suggest these tools will be valuable for expanding the scope of herbivore biology, as well as the exploration of conceptual topics in ecology.
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Affiliation(s)
- J R Malenke
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.
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21
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Miyawaki I, Tamura A, Matsumoto I, Inada H, Kunimatsu T, Kimura J, Funabashi H. The effects of clobazam treatment in rats on the expression of genes and proteins encoding glucronosyltransferase 1A/2B (UGT1A/2B) and multidrug resistance-associated protein-2 (MRP2), and development of thyroid follicular cell hypertrophy. Toxicol Appl Pharmacol 2012; 265:351-9. [PMID: 22982618 DOI: 10.1016/j.taap.2012.09.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 09/05/2012] [Accepted: 09/06/2012] [Indexed: 11/17/2022]
Abstract
Clobazam (CLB) is known to increase hepatobiliary thyroxine (T4) clearance in Sprague-Dawley (SD) rats, which results in hypothyroidism followed by thyroid follicular cell hypertrophy. However, the mechanism of the acceleration of T4-clearance has not been fully investigated. In the present study, we tried to clarify the roles of hepatic UDP-glucronosyltransferase (UGT) isoenzymes (UGT1A and UGT2B) and efflux transporter (multidrug resistance-associated protein-2; MRP2) in the CLB-induced acceleration of T4-clearance using two mutant rat strains, UGT1A-deficient mutant (Gunn) and MRP2-deficient mutant (EHBR) rats, especially focusing on thyroid morphology, levels of circulating hormones (T4 and triiodothyronine (T3)) and thyroid-stimulating hormone (TSH), and mRNA or protein expressions of UGTs (Ugt1a1, Ugt1a6, and Ugt2b1/2) and MRP2 (Mrp). CLB induced thyroid morphological changes with increases in TSH in SD and Gunn rats, but not in EHBR rats. T4 was slightly decreased in SD and Gunn rats, and T3 was decreased in Gunn rats, whereas these hormones were maintained in EHBR rats. Hepatic Ugt1a1, Ugt1a6, Ugt2b1/2, and Mrp2 mRNAs were upregulated in SD rats. In Gunn rats, UGT1A mRNAs (Ugt1a1/6) and protein levels were quite low, but UGT2B mRNAs (Ugt2b1/2) and protein were prominently upregulated. In SD and Gunn rats, MRP2 mRNA and protein were upregulated to the same degree. These results suggest that MRP2 is an important contributor in development of the thyroid cellular hypertrophy in CLB-treated rats, and that UGT1A and UGT2B work in concert with MRP2 in the presence of MRP2 function to enable the effective elimination of thyroid hormones.
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Affiliation(s)
- Izuru Miyawaki
- Safety Research Laboratories, Dainippon Sumitomo Pharma Co., Ltd., 3-1-98, Kasugade Naka, Konohanaku, Osaka 554-0022, Japan.
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22
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Richardson TA, Klaassen CD. Disruption of thyroid hormone homeostasis in Ugt1a-deficient Gunn rats by microsomal enzyme inducers is not due to enhanced thyroxine glucuronidation. Toxicol Appl Pharmacol 2010; 248:38-44. [PMID: 20655938 DOI: 10.1016/j.taap.2010.07.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Revised: 07/10/2010] [Accepted: 07/14/2010] [Indexed: 11/25/2022]
Abstract
Microsomal enzyme inducers (MEI) that increase UDP-glucuronosyltransferases (UGTs) are thought to increase glucuronidation of thyroxine (T(4)), thus reducing serum T(4), and subsequently increasing thyroid stimulating hormone (TSH). Ugt1a1 and Ugt1a6 mediate T(4) glucuronidation. Therefore, this experiment determined the involvement of Ugt1a enzymes in increased T(4) glucuronidation, decreased serum T(4), and increased TSH after MEI treatment. Male Wistar and Ugt1a-deficient Wistar (Gunn) rats were fed a control diet or diet containing pregnenolone-16α-carbonitrile (PCN; 800 ppm), 3-methylcholanthrene (3-MC; 200 ppm), or Aroclor 1254 (PCB; 100 ppm) for 7 days. Serum T(4), triiodothyronine (T(3)), and TSH concentrations, hepatic T(4)/T(3) glucuronidation, and thyroid histology and follicular cell proliferation were investigated. PCN, 3-MC, and PCB treatments decreased serum T(4), whereas serum T(3) was maintained in both Gunn and Wistar rats (except for PCB treatment). TSH was increased in Wistar and Gunn rats after PCN (130 and 277%) or PCB treatment (72 and 60%). T(4) glucuronidation in Wistar rats was increased after PCN (298%), 3-MC (85%), and PCB (450%), but was extremely low in Gunn rats, and unchanged after MEI. T(3) glucuronidation was increased after PCN (121%) or PCB (58%) in Wistar rats, but only PCN increased T(3) glucuronidation in Gunn rats (43%). PCN treatment induced thyroid morphological changes and increased follicular cell proliferation in both strains. These data demonstrate that T(4) glucuronidation cannot be increased in Ugt1a-deficient Gunn rats. Thus, the decrease in serum T(4), increase in TSH, and increase in thyroid cell proliferation after MEI are not dependent on increased T(4) glucuronidation, and cannot be attributed to Ugt1a enzymes.
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Affiliation(s)
- Terrilyn A Richardson
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160, USA
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