title: Dietary carbohydrate-to-protein ratio affects TOR signaling and metabolism-related gene expression in the liver and muscle of rainbow trout after a single meal.
abstract: Most teleost fish are known to require high levels of dietary proteins. Such high-protein intake could have significant effects, particularly on insulin-regulated gene expression. We therefore analyzed the effects of an increase in the ratio of dietary carbohydrates/proteins on the refeeding activation of the Akt-target of rapamycin (TOR) signaling pathways in rainbow trout and the effects on the expression of several genes related to hepatic and muscle metabolism and known to be regulated by insulin, amino acids, and/or glucose. Fish were fed once one of three experimental diets containing high (H), medium (M), or low (L) protein (P) or carbohydrate (C) levels after 48 h of feed deprivation. Activation of the Akt/TOR signaling pathway by refeeding was severely impaired by decreasing the proteins-to-carbohydrates ratio. Similarly, postprandial regulation of several genes related to glucose (Glut4, glucose-6-phosphatase isoform 1), lipid (fatty acid synthase, ATP-citrate lyase, sterol responsive element binding protein, carnitine palmitoyltransferase 1, and 3-hydroxyacyl-CoA dehydrogenase), and amino acid metabolism (serine dehydratase and branched-chain α-keto acid dehydrogenase E2 subunit) only occurred when fish were fed the high-protein diet. On the other hand, diet composition had a low impact on the expression of genes related to muscle protein degradation. Interestingly, glucokinase was the only gene of those monitored whose expression was significantly upregulated by increased carbohydrate intake. In conclusion, this study demonstrated that macro-nutrient composition of the diet strongly affected the insulin/amino acids signaling pathway and expression pattern of genes related to metabolism.
authors.affiliation: INRA, UMR Nutrition Aquaculture et Génomique, Saint-Pée-sur-Nivelle, France.
authors.forename: Iban
authors.initials: I
authors.lastname: Seiliez
authors.forename: Stéphane
authors.initials: S
authors.lastname: Panserat
authors.forename: Marine
authors.initials: M
authors.lastname: Lansard
authors.forename: Sergio
authors.initials: S
authors.lastname: Polakof
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Plagnes-Juan
authors.forename: Anne
authors.initials: A
authors.lastname: Surget
authors.forename: Karine
authors.initials: K
authors.lastname: Dias
authors.forename: Mélanie
authors.initials: M
authors.lastname: Larquier
authors.forename: Sadasivam
authors.initials: S
authors.lastname: Kaushik
authors.forename: Sandrine
authors.initials: S
authors.lastname: Skiba-Cassy
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D004040:Dietary Carbohydrates / Q000097:blood / Q000378:metabolism*; D004044:Dietary Proteins / Q000097:blood / Q000378:metabolism*; D004734:Energy Metabolism / Q000235:genetics; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism*; D017686:Oncorhynchus mykiss / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D029941:Fish Proteins; D012333:RNA, Messenger; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases