Hepatic insulin-like growth-factor binding protein (igfbp) responses tofood restriction in Atlantic salmon smolts

General and Comparative Endocrinology
By: , and 

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Abstract

The growth hormone (Gh)/insulin-like growth-factor (Igf) system plays a central role in the regulation of growth in fishes. However, the roles of Igf binding proteins (Igfbps) in coordinating responses to food availability are unresolved, especially in anadromous fishes preparing for seaward migration. We assayed plasma Gh, Igf1, thyroid hormones and cortisol along with igfbp mRNA levels in fasted and fed Atlantic salmon ( Salmo salar ). Fish were fasted for 3 or 10 days near the peak of smoltification (late April to early May). Fasting reduced plasma glucose by 3 days and condition factor by 10 days. Plasma Gh, cortisol, and thyroxine (T ) were not altered in response to fasting, whereas Igf1 and 3,5,3′-triiodo- -thyronine (T ) were slightly higher and lower than controls, respectively. Hepatic igfbp1b1 , - 1b2 , - 2a , - 2b1 and - 2b2 mRNA levels were not responsive to fasting, but there were marked increases in igfbp1a1 following 3 and 10 days of fasting. Fasting did not alter hepatic igf1or igf2 ; however, muscle igf1 was diminished by 10 days of fasting. There were no signs that fasting compromised branchial ionoregulatory functions, as indicated by unchanged Na /K -ATPase activity and ion pump/transporter mRNA levels. We conclude that dynamic hepatic igfbp1a1 and muscle igf1 expression participate in the modulation of Gh/Igf signaling in smolts undergoing catabolism.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Hepatic insulin-like growth-factor binding protein (igfbp) responses tofood restriction in Atlantic salmon smolts
Series title General and Comparative Endocrinology
DOI 10.1016/j.ygcen.2016.05.015
Volume 233
Year Published 2016
Language English
Publisher Elsevier
Contributing office(s) Leetown Science Center
Description 8 p.
First page 79
Last page 87
Online Only (Y/N) N
Additional Online Files (Y/N) N