Effect of Cortisol on Growth and Gene Expression of insulin‐like growth‐factor binding proteins (igfbps) in Atlantic Salmon Parr

Abstract

Growth performance of teleost fishes, including salmonids, is principally controlled by the growth hormone (Gh)/insulin‐like growth‐factor (Igf) axis. Igfs interact with cognate binding proteins, termed Igf binding proteins (Igfbps), which modulate the biological activities of Igfs. While Atlantic salmon (Salmo salar) are known to express an expansive set of igfbp transcripts in several key metabolic tissues, the actual regulators of igfbp expression have not been identified. Given the well‐documented consequences of mounting a glucocorticoid stress response on growth, we hypothesized that cortisol inhibits anabolic processes by directing the dynamic expression of igfbps. We therefore examined changes in the activities of the Gh/Igf/Igfbp network of salmon parr implanted with cortisol (0, 10 and 40 μg/g body weight) and sampled after 3 or 14 days. We observed reductions in body mass and fork length following 3‐ and 14‐day treatments with cortisol at 40 μg/g. A dose dependent reduction in growth rate occurred by 14 days of treatment with cortisol, whereas hepatosomatic index was not affected. We will report igfbp transcript levels in liver, skeletal muscle and gill with an aim to resolve how activities within the Igfbp network are modulated by cortisol in juvenile Atlantic salmon.Support or Funding InformationSupported by Start‐Up funds to J.P.B.