|Thyroid dysfunction in sea bass (Dicentrarchus labrax): Underlying mechanisms and effects of polychlorinated biphenyls on thyroid hormone physiology and metabolism|
|Schnitzler, J.G.; Celis, N.; Klaren, P.H.M.; Blust, R.; Dirtu, A.C.; Covac, A.; Das, K. (2011). Thyroid dysfunction in sea bass (Dicentrarchus labrax): Underlying mechanisms and effects of polychlorinated biphenyls on thyroid hormone physiology and metabolism. Aquat. Toxicol. 105(3-4): 438-447. dx.doi.org/10.1016/j.aquatox.2011.07.019|
|In: Aquatic Toxicology. Elsevier Science: Amsterdam. ISSN 0166-445X, more|
Hormones; Polychlorinated biphenyls; Sulfation; Thyroid; Dicentrarchus labrax (Linnaeus, 1758) [WoRMS]; Marine
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The current study examines the effect of subchronic exposure to a mixture of Aroclor standards on thyroid hormone physiology and metabolism in juvenile sea bass. The contaminant mixture was formulated to reflect the persistent organic pollution to which the European sea bass population could conceivably be exposed (0.3, 0.6 and 1.0 µg S7PCBs per g food pellets) and higher (10 µg S7PCBs per g food pellets). After 120 days of exposure, histomorphometry of thyroid tissue, muscular thyroid hormone concentration and activity of enzymes involved in metabolism of thyroid hormones were assessed. Mean concentrations of 8, 86, 142, 214 and 2279 ng g-1 ww (S7 ICES PCB congeners) were determined after 120 days exposure. The results show that the effects of PCB exposures on the thyroid system are dose-dependent. Exposure to environmentally relevant doses of PCB (0.3–1.0 µg S7PCBs per g food pellets) induced a larger variability of the follicle diameter and stimulated hepatic T4 outer ring deiodinase. Muscular thyroid hormone levels were preserved thanks to the PCB induced changes in T4 dynamics. At 10 times higher concentrations (10 µg S7PCBs per g food pellets) an important depression of T3 and T4 levels could be observed which are apparently caused by degenerative histological changes in the thyroid tissue.