title: Macronutrient-induced differences in food intake relate with hepatic oxidative metabolism and hypothalamic regulatory neuropeptides in rainbow trout (Oncorhynchus mykiss).
abstract: This study examines how dietary macronutrient-induced changes in voluntary food intake (FI) relate to changes in markers of hepatic oxidative metabolism and in the expression of FI regulatory neuropeptides in a teleost model, the rainbow trout. Rainbow trout were fed for 6weeks with one of four iso-energetic diets (2×2 factorial design), containing either a high (HP, ~500 g·kg(-1) DM) or a low (LP, ~250 g·kg(-1) DM) protein level (PL) with, at each PL, fat (diets HP-F and LP-F) being substituted by an iso-energetic amount of gelatinized corn starch (diets HP-St and LP-St) as non-protein energy source (ES). Irrespective of the dietary PL, FI (g·kg(-0.8)·d(-1)) and digestible energy intake (DEI, kJ·kg(-0.8)·d(-1)) were significantly (P<0.05) reduced by the iso-energetic replacement of fat by starch as non-protein ES. Interestingly, trout fed these St-diets had higher gene expression of markers of hepatic oxidative phosphorylation (OxPhos), i.e., ubiquinol-cytochrome c reductase subunit 2 (UCR2) and cytochrome oxidase subunit 4 (COX4) and of aerobic oxidative capacity (CS, citrate synthase), which paralleled glucokinase (GK) transcription. This positive relation suggests that glucose phosphorylation and markers of mitochondrial OxPhos are linked at the hepatic level and possibly triggered the observed reduction in FI. Moreover, trout displaying the reduced FI had higher cocaine amphetamine regulator transcript (CART) mRNA in hypothalamus, whereas neuropeptide Y (NPY) mRNA did not follow the macronutrient-induced changes in FI. Further studies are needed to unravel the mechanisms by which diet-induced changes in hepatic metabolism inform central feeding centers involved in the regulation of FI in fish.
authors.affiliation: INRA, UR1067 Nutrition Metabolism Aquaculture, F-64310 Saint Pée-sur-Nivelle, France.
authors.forename: A Cláudia
authors.initials: AC
authors.lastname: Figueiredo-Silva
authors.forename: Subramanian
authors.initials: S
authors.lastname: Saravanan
authors.forename: Johan W
authors.initials: JW
authors.lastname: Schrama
authors.forename: Sadasivam
authors.initials: S
authors.lastname: Kaushik
authors.forename: Inge
authors.initials: I
authors.lastname: Geurden
mesh_terms: D000818:Animals; D001823:Body Composition / Q000502:physiology; D004032:Diet; D004041:Dietary Fats / Q000494:pharmacology; D004435:Eating / Q000502:physiology*; D002149:Energy Intake / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology; D015870:Gene Expression / Q000187:drug effects; D006128:Growth / Q000502:physiology; D006706:Homeostasis / Q000502:physiology; D007031:Hypothalamus / Q000502:physiology*; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009478:Neuropeptide Y / Q000378:metabolism; D009479:Neuropeptides / Q000502:physiology*; D017686:Oncorhynchus mykiss / Q000502:physiology*; D010084:Oxidation-Reduction; D010085:Oxidative Phosphorylation / Q000187:drug effects; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D013213:Starch / Q000494:pharmacology; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein
chemical_list: D004041:Dietary Fats; D009419:Nerve Tissue Proteins; D009478:Neuropeptide Y; D009479:Neuropeptides; D012333:RNA, Messenger; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein; D013213:Starch