Hepatic protein kinase B (Akt)-target of rapamycin (TOR)-signalling pathways and intermediary metabolism in rainbow trout (Oncorhynchus mykiss) are not significantly affected by feeding plant-based diets.
The aim of the present study was to analyse the effects of partial or total replacement of fish meal (FM) and fish oil (FO) by a mixture of plant protein (PP) and a mixture of vegetable oils (VO) on the hepatic insulin-nutrient-signalling pathway and intermediary metabolism-related gene expression in rainbow trout (Oncorhynchus mykiss). Triplicate groups of fish were fed four practical diets containing graded levels of replacement of FM and FO by PP and VO for 12 weeks: diet 0/0 (100 % FM, 100 % FO); diet 50/50 (50 % FM and 50 % PP, 50 % FO and 50 % VO); diet 50/100 (50 % FM and 50 % PP, 100 % VO); diet 100/100 (100 % PP, 100 % VO). Samplings were performed on trout starved for 5 d then refed with their allocated diet. In contrast to partial substitution (diet 50/50), total substitution of FM and FO (diet 100/100) led to significantly lower growth compared with diet 0/0. The insulin-nutrient-signalling pathway (protein kinase B (Akt), target of rapamycin (TOR), S6 protein kinase 1 (S6K1) and S6) was characterised in trout liver and found to be activated by refeeding. However, changes in diet compositions did not differentially affect the Akt-TOR-signalling pathway. Moreover, expression of genes encoding fructose-1,6-biphosphatase, mitochondrial phosphoenolpyruvate carboxykinase, glucokinase, pyruvate kinase and carnitine palmitoyl transferase 1 were not affected by refeeding or by dietary changes. Refeeding down- and up-regulated the expression of gluconeogenic glucose-6-phosphatase isoform 1 and lipogenic fatty acid synthase genes, respectively. Expression of both genes was also increased with partial replacement of FM and total replacement of FO (diet 50/100). These findings indicate that plant-based diets barely affect glucose and lipid metabolism in trout.
Lansard
Marine
M
Institut National de la Recherche Agronomique, UMR1067 Nutrition Aquaculture et Génomique, Pôle d'hydrobiologie, St-Pée-sur-Nivelle, France.
Panserat
Stéphane
S
Seiliez
Iban
I
Polakof
Sergio
S
Plagnes-Juan
Elisabeth
E
Geurden
Inge
I
Médale
Françoise
F
Kaushik
Sadasivam
S
Corraze
Geneviève
G
Skiba-Cassy
Sandrine
S
D000824:Animal Nutritional Physiological Phenomena / Q000502:physiology*; D000818:Animals; D004032:Diet; D014676:Diet, Vegetarian; D029941:Fish Proteins / Q000378:metabolism*; D005398:Fisheries; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology; D008099:Liver / Q000378:metabolism; D017686:Oncorhynchus mykiss / Q000097:blood / Q000254:growth & development / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D010938:Plant Oils / Q000494:pharmacology; D014674:Plant Proteins, Dietary / Q000494:pharmacology; D019518:Postprandial Period / Q000502:physiology; D011494:Protein Kinases / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D015430:Weight Gain / Q000187:drug effects / Q000502:physiology
D029941:Fish Proteins; D010938:Plant Oils; D014674:Plant Proteins, Dietary; D011494:Protein Kinases; D051057:Proto-Oncogene Proteins c-akt