title: Chronic exposure to pentachlorophenol alters thyroid hormones and thyroid hormone pathway mRNAs in zebrafish.
abstract: Pentachlorophenol (PCP) is frequently detected in the aquatic environment and has been implicated as an endocrine disruptor in fish. In the present study, 4-month-old zebrafish (Danio rerio) were exposed to 1 of 4 concentrations of PCP (0.1, 1, 9, and 27 µg/L) for 70 d. The effects of PCP exposure on plasma thyroid hormone levels, and the expression levels of selected genes, were measured in the brain and liver. The PCP exposure at 27 µg/L resulted in elevated plasma thyroxine concentrations in male and female zebrafish and depressed 3, 5, 3'-triiodothyronine concentrations in males only. In both sexes, PCP exposure resulted in decreased messenger RNA (mRNA) expression levels of thyroid-stimulating hormone β-subunit (tshβ) and thyroid hormone receptor β (trβ) in the brain, as well as increased liver levels of uridine diphosphoglucuronosyl transferase (ugt1ab) and decreased deiodinase 1 (dio1). The authors also identified several sex-specific effects of PCP exposure, including changes in mRNA levels for deiodinase 2 (dio2), cytosolic sulfotransferase (sult1 st5), and transthyretin (ttr) genes in the liver. Environmental PCP exposure also caused an increased malformation rate in offspring that received maternal exposure to PCP. The present study demonstrates that chronic exposure to environmental levels of PCP alters plasma thyroid hormone levels, as well as the expression of genes associated with thyroid hormone signaling and metabolism in the hypothalamic-pituitary-thyroid (HPT) axis and liver, resulting in abnormal zebrafish development.
authors.affiliation: China Institute of Water Resources and Hydropower Research, Beijing, China.
authors.forename: Li-Qin
authors.initials: LQ
authors.lastname: Yu
authors.forename: Gao-Feng
authors.initials: GF
authors.lastname: Zhao
authors.forename: Min
authors.initials: M
authors.lastname: Feng
authors.forename: Wu
authors.initials: W
authors.lastname: Wen
authors.forename: Kun
authors.initials: K
authors.lastname: Li
authors.forename: Pan-Wei
authors.initials: PW
authors.lastname: Zhang
authors.forename: Xi
authors.initials: X
authors.lastname: Peng
authors.forename: Wei-Jie
authors.initials: WJ
authors.lastname: Huo
authors.forename: Huai-Dong
authors.initials: HD
authors.lastname: Zhou
mesh_terms: D000818:Animals; D015239:Arylsulfotransferase / Q000235:genetics; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D005260:Female; D014453:Glucuronosyltransferase / Q000235:genetics; D007453:Iodide Peroxidase / Q000235:genetics; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D010416:Pentachlorophenol / Q000633:toxicity*; D011228:Prealbumin / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D037042:Thyroid Hormone Receptors beta / Q000235:genetics; D013963:Thyroid Hormones / Q000097:blood*; D037322:Thyrotropin, beta Subunit / Q000235:genetics; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015027:Zebrafish / Q000235:genetics / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000235:genetics; D000099148:UGT1A1 Enzyme
chemical_list: D015239:Arylsulfotransferase; D014453:Glucuronosyltransferase; D007453:Iodide Peroxidase; D010416:Pentachlorophenol; D011228:Prealbumin; D012333:RNA, Messenger; D037042:Thyroid Hormone Receptors beta; D013963:Thyroid Hormones; D037322:Thyrotropin, beta Subunit; D014874:Water Pollutants, Chemical; D029961:Zebrafish Proteins; D000099148:UGT1A1 Enzyme; C501250:sult1st4 protein, zebrafish
keywords: Gene expression; Hypothalamic-pituitary-thyroid axis; Pentachlorophenol; Thyroid hormone; Zebrafish