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Daily endocrine profiles in parr and smolt Atlantic salmon.
Comp Biochem Physiol A Mol Integr Physiol. 2008 Dec; 151(4):698-704.CB

Abstract

To elucidate possible mechanisms behind the endocrine control of parr-smolt transformation, the daily plasma profiles in thyroid hormones (TH; free thyroxine (FT(4)), total thyroxine (TT(4)), and total 3,5,3'-triiodothyronine (TT(3))), growth hormone (GH) and cortisol were studied in Atlantic salmon parr and smolts under simulated-natural winter (8 L:16D) and spring (16.5 L:7.5D) photoperiods, respectively. Overall, TT(4), TT(3) and GH levels were higher in smolts than in parr, whereas FT(4) levels fluctuated within the same range in parr and smolts. Significant diurnal changes in plasma TH were present in parr. Both FT(4) and TT(4) levels increased during the photophase and decreased during the scotophase, while TT(3) levels followed an inverse pattern. Growth hormone showed no significant changes in parr. Changes in FT(4), TT(4), GH, and cortisol, but not TT(3), levels, were observed in smolts with peak levels during both the photophase and scotophase for FT(4), TT(4) and GH. Plasma cortisol was not assayed in parr but in smolts the peaks were associated with dusk and dawn. In addition to the general increases in TH, GH and cortisol, the distinct endocrine differences in nighttime levels between parr in the winter and smolts in the spring suggest different interactions between TH, GH, cortisol and melatonin at these different time points. These spring scotophase endocrine profiles may represent synergistic hormone interactions that promote smolt development, similar to the synergistic endocrine interactions shown to accelerate anuran metamorphosis. The variations in these diurnal rhythms between parr and smolts may represent part of the endocrine mechanism for the translation of seasonal information during salmon smoltification.

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Publisher Full Text (DOI)

Authors+Show Affiliations

Ebbesson LO
Department Biology, University of Bergen, High Technology Centre, N-5020 Bergen, Norway. lars.ebbesson@bio.uib.no
Björnsson BT
No affiliation info available
Ekström P
No affiliation info available
Stefansson SO
No affiliation info available

MeSH

AnimalsCircadian RhythmGrowth HormoneHydrocortisoneMetamorphosis, BiologicalPhotoperiodSalmo salarSeasonsThyroid HormonesThyroxineTriiodothyronine

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

18790069

Citation

Ebbesson, Lars O E., et al. "Daily Endocrine Profiles in Parr and Smolt Atlantic Salmon." Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology, vol. 151, no. 4, 2008, pp. 698-704.
Ebbesson LO, Björnsson BT, Ekström P, et al. Daily endocrine profiles in parr and smolt Atlantic salmon. Comp Biochem Physiol A Mol Integr Physiol. 2008;151(4):698-704.
Ebbesson, L. O., Björnsson, B. T., Ekström, P., & Stefansson, S. O. (2008). Daily endocrine profiles in parr and smolt Atlantic salmon. Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology, 151(4), 698-704. https://doi.org/10.1016/j.cbpa.2008.08.017
Ebbesson LO, et al. Daily Endocrine Profiles in Parr and Smolt Atlantic Salmon. Comp Biochem Physiol A Mol Integr Physiol. 2008;151(4):698-704. PubMed PMID: 18790069.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Daily endocrine profiles in parr and smolt Atlantic salmon. AU - Ebbesson,Lars O E, AU - Björnsson,Björn Th, AU - Ekström,Peter, AU - Stefansson,Sigurd O, Y1 - 2008/08/24/ PY - 2008/05/07/received PY - 2008/08/13/revised PY - 2008/08/18/accepted PY - 2008/9/16/pubmed PY - 2009/12/30/medline PY - 2008/9/16/entrez SP - 698 EP - 704 JF - Comparative biochemistry and physiology. Part A, Molecular & integrative physiology JO - Comp Biochem Physiol A Mol Integr Physiol VL - 151 IS - 4 N2 - To elucidate possible mechanisms behind the endocrine control of parr-smolt transformation, the daily plasma profiles in thyroid hormones (TH; free thyroxine (FT(4)), total thyroxine (TT(4)), and total 3,5,3'-triiodothyronine (TT(3))), growth hormone (GH) and cortisol were studied in Atlantic salmon parr and smolts under simulated-natural winter (8 L:16D) and spring (16.5 L:7.5D) photoperiods, respectively. Overall, TT(4), TT(3) and GH levels were higher in smolts than in parr, whereas FT(4) levels fluctuated within the same range in parr and smolts. Significant diurnal changes in plasma TH were present in parr. Both FT(4) and TT(4) levels increased during the photophase and decreased during the scotophase, while TT(3) levels followed an inverse pattern. Growth hormone showed no significant changes in parr. Changes in FT(4), TT(4), GH, and cortisol, but not TT(3), levels, were observed in smolts with peak levels during both the photophase and scotophase for FT(4), TT(4) and GH. Plasma cortisol was not assayed in parr but in smolts the peaks were associated with dusk and dawn. In addition to the general increases in TH, GH and cortisol, the distinct endocrine differences in nighttime levels between parr in the winter and smolts in the spring suggest different interactions between TH, GH, cortisol and melatonin at these different time points. These spring scotophase endocrine profiles may represent synergistic hormone interactions that promote smolt development, similar to the synergistic endocrine interactions shown to accelerate anuran metamorphosis. The variations in these diurnal rhythms between parr and smolts may represent part of the endocrine mechanism for the translation of seasonal information during salmon smoltification. SN - 1531-4332 UR - https://www.unboundmedicine.com/medline/citation/18790069/Daily_endocrine_profiles_in_parr_and_smolt_Atlantic_salmon_ DB - PRIME DP - Unbound Medicine ER -