Dietary methionine level affects growth performance and hepatic gene expression of GH-IGF system and protein turnover regulators in rainbow trout (Oncorhynchus mykiss) fed plant protein-based diets

• Published in: Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology
• Main Authors: Rolland, Marine, Dalsgaard, Anne Johanne Tang, Holm, Jorgen, Gomez-Requeni, Pedro, Skov, Peter Vilhelm
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2015
• Subjects: BIOCHEMISTRY; ZOOLOGY; BREAM SPARUS-AURATA; MESSENGER-RNA EXPRESSION; FACTOR-BINDING PROTEIN-1; AMINO-ACID-CONCENTRATIONS; FACTOR-I; DIFFERENTIAL EXPRESSION; NITROGEN-UTILIZATION; SOMATOTROPIC AXIS; ATLANTIC SALMON; MUSCLE GROWTH; Fish; Crystalline amino acid; Proteolytic pathways; TOR; Atlantic salmon
• Online Access: https://orbit.dtu.dk/en/publications/14b68e63-6a17-4698-8dcf-6c8036688768; https://doi.org/10.1016/j.cbpb.2014.11.009

The effects of dietary level of methionine were investigated in juvenile rainbow trout (Oncorhynchus mykiss) fed five plant-based diets containing increasing content of crystalline methionine (Met), in a six week growth trial. Changes in the hepatic expression of genes related to i) the somatotropic axis: including the growth hormone receptor I (GHR-I), insulin-like growth hormones land II (IGF-I and IGF-II, respectively), and insulin-like growth hormone binding protein-1b (IGFBP-1b); and ii) protein turnover: including the target of rapamycin protein (TOR), proteasome 20 delta (Prot 20D), cathepsin L, calpains 1 and 2 (Capn 1 and Capn 2, respectively), and calpastatin long and short isoforms (CAST-L and CAST-S, respectively) were measured for each dietary treatment. The transcript levels of GHR-I and IGF-I increased linearly with the increase of dietary Met content (P <0.01), reflecting overall growth performances. The apparent capacity for hepatic protein degradation (derived from the gene expression of TOR, Prot 20D, Capn 1, Capn 2, CAST-L and CAST-S) decreased with increasing dietary Met level in a relatively linear manner. Our results suggest that Met availability affects, directly or indirectly, the expression of genes involved in the GH/IGF axis response and protein turnover, which are centrally involved in the regulation of growth. (C) 2014 Elsevier Inc. All rights reserved.