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Daily endocrine profiles in parr and smolt Atlantic salmon.

Ebbesson, Lars LU ; Björnsson, Björn Th; Ekström, Peter LU and Stefansson, Sigurd O (2008) In Comparative Biochemistry and Physiology A 151. p.698-704
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... (More)
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. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Development, Diurnal, Fish, Hormone, Photoperiod, Rhythm, Salmo salar, Smoltification
in
Comparative Biochemistry and Physiology A
volume
151
pages
698 - 704
publisher
Elsevier
external identifiers
  • wos:000261250700031
  • scopus:54349097208
ISSN
1531-4332
DOI
10.1016/j.cbpa.2008.08.017
language
English
LU publication?
yes
id
aade0eb7-e284-42e2-8d67-e1182f311a4a (old id 1243032)
date added to LUP
2008-10-22 15:47:21
date last changed
2017-08-06 03:50:31
@article{aade0eb7-e284-42e2-8d67-e1182f311a4a,
  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.},
  author       = {Ebbesson, Lars and Björnsson, Björn Th and Ekström, Peter and Stefansson, Sigurd O},
  issn         = {1531-4332},
  keyword      = {Development,Diurnal,Fish,Hormone,Photoperiod,Rhythm,Salmo salar,Smoltification},
  language     = {eng},
  pages        = {698--704},
  publisher    = {Elsevier},
  series       = {Comparative Biochemistry and Physiology A},
  title        = {Daily endocrine profiles in parr and smolt Atlantic salmon.},
  url          = {http://dx.doi.org/10.1016/j.cbpa.2008.08.017},
  volume       = {151},
  year         = {2008},
}