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Free plasma thyroxine levels in coho salmon, Oncorhynchus kisutch, during parr-smolt transformation : Comparison with total thyroxine, total triiodothyronine, and growth hormone levels

Ebbesson, Lars O.E. LU ; Björnsson, Björn Th ; Stefansson, Sigurd O. and Ekström, Peter LU (2000) In Fish Physiology and Biochemistry 22(1). p.45-50
Abstract

Free plasma thyroxine (FT4) levels were measured in coho salmon, Oncorhynchus kisutch, during parr-smolt transformation (smoltification) using an equilibrium dialysis system followed by a radioimmunoassay. The FT4 data were correlated to total plasma thyroxine (TT4), triiodothyronine (TT3), and growth hormone (GH). Plasma samples were taken weekly from early April to late May, when the salmon where released from the hatchery. Free thyroxine and GH levels increased gradually through smoltification. TT4 levels increased significantly in mid-April and in mid-May. TT3 levels increased in April and remained elevated until late-May after which they declined to the lowest... (More)

Free plasma thyroxine (FT4) levels were measured in coho salmon, Oncorhynchus kisutch, during parr-smolt transformation (smoltification) using an equilibrium dialysis system followed by a radioimmunoassay. The FT4 data were correlated to total plasma thyroxine (TT4), triiodothyronine (TT3), and growth hormone (GH). Plasma samples were taken weekly from early April to late May, when the salmon where released from the hatchery. Free thyroxine and GH levels increased gradually through smoltification. TT4 levels increased significantly in mid-April and in mid-May. TT3 levels increased in April and remained elevated until late-May after which they declined to the lowest levels. During the first increase in TT4 levels, FT4 levels remained low and TT3 levels did not increase until FT4 levels increased in late-April. In addition, after TT4 levels decreased in late May, FT4 levels remained elevated. These data show that there are differences between the plasma FT4 and TT4 profiles during smoltification. Nevertheless, regression analysis indicates that FT4 levels are highly correlated to the increases in the levels of GH (r=0.73) and TT4 (r=0.70). In addition, GH is less correlated to TT4 and TT3 (r = 0.24 and r = -0.46, respectively) compared with FT4 (r = 0.73), suggesting a close relationship between the increases of FT4 and GH. In addition, these data suggest that this method of measuring free plasma thyroxine may provide a new tool for studying the timing of thyroid hormone action and regulation during parr-smolt transformation in salmonids.

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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Development, Endocrine regulation, Environment, Fish, Plasma proteins, Radioimmunoassay, Smoltification, Teleost
in
Fish Physiology and Biochemistry
volume
22
issue
1
pages
45 - 50
publisher
Springer
external identifiers
  • scopus:0037794870
ISSN
0920-1742
DOI
10.1023/A:1007841517552
language
English
LU publication?
yes
id
29724753-8366-4cca-a2d6-6cbff04a6b8a
date added to LUP
2019-10-02 14:47:33
date last changed
2020-06-24 05:55:41
@article{29724753-8366-4cca-a2d6-6cbff04a6b8a,
  abstract     = {<p>Free plasma thyroxine (FT<sub>4</sub>) levels were measured in coho salmon, Oncorhynchus kisutch, during parr-smolt transformation (smoltification) using an equilibrium dialysis system followed by a radioimmunoassay. The FT<sub>4</sub> data were correlated to total plasma thyroxine (TT<sub>4</sub>), triiodothyronine (TT<sub>3</sub>), and growth hormone (GH). Plasma samples were taken weekly from early April to late May, when the salmon where released from the hatchery. Free thyroxine and GH levels increased gradually through smoltification. TT<sub>4</sub> levels increased significantly in mid-April and in mid-May. TT<sub>3</sub> levels increased in April and remained elevated until late-May after which they declined to the lowest levels. During the first increase in TT<sub>4</sub> levels, FT<sub>4</sub> levels remained low and TT<sub>3</sub> levels did not increase until FT<sub>4</sub> levels increased in late-April. In addition, after TT<sub>4</sub> levels decreased in late May, FT<sub>4</sub> levels remained elevated. These data show that there are differences between the plasma FT<sub>4</sub> and TT<sub>4</sub> profiles during smoltification. Nevertheless, regression analysis indicates that FT<sub>4</sub> levels are highly correlated to the increases in the levels of GH (r=0.73) and TT<sub>4</sub> (r=0.70). In addition, GH is less correlated to TT<sub>4</sub> and TT<sub>3</sub> (r = 0.24 and r = -0.46, respectively) compared with FT<sub>4</sub> (r = 0.73), suggesting a close relationship between the increases of FT<sub>4</sub> and GH. In addition, these data suggest that this method of measuring free plasma thyroxine may provide a new tool for studying the timing of thyroid hormone action and regulation during parr-smolt transformation in salmonids.</p>},
  author       = {Ebbesson, Lars O.E. and Björnsson, Björn Th and Stefansson, Sigurd O. and Ekström, Peter},
  issn         = {0920-1742},
  language     = {eng},
  number       = {1},
  pages        = {45--50},
  publisher    = {Springer},
  series       = {Fish Physiology and Biochemistry},
  title        = {Free plasma thyroxine levels in coho salmon, Oncorhynchus kisutch, during parr-smolt transformation : Comparison with total thyroxine, total triiodothyronine, and growth hormone levels},
  url          = {http://dx.doi.org/10.1023/A:1007841517552},
  doi          = {10.1023/A:1007841517552},
  volume       = {22},
  year         = {2000},
}