title: Characterization of the peripheral thyroid system of gilthead seabream acclimated to different ambient salinities.
abstract: Thyroid hormones are involved in many developmental and physiological processes, including osmoregulation. The regulation of the thyroid system by environmental salinity in the euryhaline gilthead seabream (Sparus aurata) is still poorly characterized. To this end seabreams were exposed to four different environmental salinities (5, 15, 40 and 55ppt) for 14days, and plasma free thyroid hormones (fT3, fT4), outer ring deiodination and Na+/K+-ATPase activities in gills and kidney, as well as other osmoregulatory and metabolic parameters were measured. Low salinity conditions (5ppt) elicited a significant increase in fT3 (29%) and fT4 (184%) plasma concentrations compared to control animals (acclimated to 40ppt, natural salinity conditions in the Bay of Cádiz, Spain), while the amount of pituitary thyroid stimulating hormone subunit β (tshb) transcript abundance remained unchanged. In addition, plasma fT4 levels were positively correlated to renal and branchial deiodinase type 2 (dio2) mRNA expression. Gill and kidney T4-outer ring deiodination activities correlated positively with dio2 mRNA expression and the highest values were observed in fish acclimated to low salinities (5 and 15ppt). The high salinity (55ppt) exposure caused a significant increase in tshb expression (65%), but deiodinase gene expression (dio1 and dio2) and activity did not change and were similar to controls (40ppt). In conclusion, acclimation to different salinities led to changes in the peripheral regulation of thyroid hormone metabolism in seabream. Therefore, thyroid hormones are involved in the regulation of ion transport and osmoregulatory physiology in this species. The conclusions derived from this study may also allow aquaculturists to modulate thyroid metabolism in seabream by adjusting culture salinity.
authors: Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Av. República Saharaui s/n, E11519 Puerto Real, Cádiz, Spain; Comparative Endocrinology and Integrative Biology Group, Centre of Marine Sciences (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal. Electronic address: ignacio.ruizjarabo@uca.es.
authors: I
authors: I
authors: Ruiz-Jarabo
authors: Department of Animal Ecology & Physiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, Heyendaalseweg 135, Box 30, 6525 AJ Nijmegen, The Netherlands.
authors: P H M
authors: PH
authors: Klaren
authors: Comparative Endocrinology and Integrative Biology Group, Centre of Marine Sciences (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
authors: B
authors: B
authors: Louro
authors: Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Av. República Saharaui s/n, E11519 Puerto Real, Cádiz, Spain; Instituto de Ciencias Marinas de Andalucía (ICMAN-CSIC), Spanish National Research Council, Av. República Saharaui, 2, E11519 Puerto Real, Cádiz, Spain.
authors: J A
authors: JA
authors: Martos-Sitcha
authors: Comparative Endocrinology and Integrative Biology Group, Centre of Marine Sciences (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
authors: P I S
authors: PI
authors: Pinto
authors: Instituto de Ciencias Marinas y Limnológicas, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile.
authors: L
authors: L
authors: Vargas-Chacoff
authors: Department of Animal Ecology & Physiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, Heyendaalseweg 135, Box 30, 6525 AJ Nijmegen, The Netherlands.
authors: G
authors: G
authors: Flik
authors: Instituto de Ciencias Marinas de Andalucía (ICMAN-CSIC), Spanish National Research Council, Av. República Saharaui, 2, E11519 Puerto Real, Cádiz, Spain.
authors: G
authors: G
authors: Martínez-Rodríguez
authors: Comparative Endocrinology and Integrative Biology Group, Centre of Marine Sciences (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
authors: D M
authors: DM
authors: Power
authors: Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Av. República Saharaui s/n, E11519 Puerto Real, Cádiz, Spain.
authors: J M
authors: JM
authors: Mancera
authors: Departamento de Biología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Av. República Saharaui s/n, E11519 Puerto Real, Cádiz, Spain; Department of Animal Ecology & Physiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, Heyendaalseweg 135, Box 30, 6525 AJ Nijmegen, The Netherlands.
authors: F J
authors: FJ
authors: Arjona
mesh_terms: D000465:Algorithms; D000818:Animals; D060888:Real-Time Polymerase Chain Reaction; D054712:Salinity; D021541:Sea Bream / Q000502:physiology*; D013961:Thyroid Gland / Q000502:physiology*; D013974:Thyroxine / Q000097:blood
chemical_list: D013974:Thyroxine
keywords: Deiodinases; Osmoregulation; Outer ring deiodination; Sparus aurata; Thyroid hormones