title: Deiodinases and thyroid metabolism disruption in teleost fish.
abstract: Many xenobiotic compounds with endocrine disrupting activity have been described since the late eighties. These compounds are able to interact with natural hormone systems and potentially induce deleterious effects in wildlife, notably piscine species. However, while the characterization of endocrine disruptors with "dioxin-like", estrogenic or androgenic activities is relatively well established, little is known about environmentally relevant pollutants that may act at thyroid system level. Iodothyronine deiodinases, the key enzymes in the activation and inactivation of thyroid hormones, have been suggested as suitable biomarkers for thyroid metabolism disruption. The present article reviews the biotic and abiotic factors that are able to modulate deiodinases in teleosts, a representative model organism for vertebrates. Data show that deiodinases are highly sensitive to several physiological and physical variables, so they should be taken into account to establish natural basal deiodination patterns to further understand responses under chemical exposure. Among xenobiotic compounds, brominated flame retardants are postulated as chemicals of major concern because of their similar structure shared with thyroid hormones. More ambiguous results are shown for the rest of compounds, i.e. polychlorinated biphenyls, perfluorinated chemicals, pesticides, metals and synthetic drugs, in part due to the limited information available. The different mechanisms of action still remain unknown for most of those compounds, although several hypothesis based on observed effects are discussed. Future tasks are also suggested with the aim of moving forward in the full characterization of chemical compounds with thyroid disrupting activity.
authors.affiliation: Masaryk University, Faculty of Science, RECETOX, Kamenice 5/753, CZ62500 Brno, Czech Republic. Electronic address: jarque@recetox.muni.cz.
authors.forename: Sergio
authors.initials: S
authors.lastname: Jarque
authors.affiliation: Institute of Environmental Assessment and Water Research, IDAEA-CSIC, Jordi Girona, 18, 08034 Barcelona, Spain. Electronic address: benjami.pina@idaea.csic.es.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Piña
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism*; D052244:Endocrine Disruptors / Q000009:adverse effects*; D004785:Environmental Pollutants / Q000009:adverse effects*; D005399:Fishes / Q000378:metabolism*; D005411:Flame Retardants / Q000009:adverse effects; D007453:Iodide Peroxidase / Q000737:chemistry / Q000378:metabolism*; D008954:Models, Biological; D015394:Molecular Structure; D012016:Reference Values; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism*; D013963:Thyroid Hormones / Q000737:chemistry / Q000378:metabolism; D015262:Xenobiotics / Q000009:adverse effects*
chemical_list: D015415:Biomarkers; D052244:Endocrine Disruptors; D004785:Environmental Pollutants; D005411:Flame Retardants; D013963:Thyroid Hormones; D015262:Xenobiotics; D007453:Iodide Peroxidase
keywords: Environmental pollutants; Iodothyronine deiodinases; Physical factors; Teleosts; Thyroid disruption