title: Regulation of glucose and lipid metabolism by dietary carbohydrate levels and lipid sources in gilthead sea bream juveniles.
abstract: The long-term effects on growth performance, body composition, plasma metabolites, liver and intestine glucose and lipid metabolism were assessed in gilthead sea bream juveniles fed diets without carbohydrates (CH-) or carbohydrate-enriched (20 % gelatinised starch, CH+) combined with two lipid sources (fish oil; or vegetable oil (VO)). No differences in growth performance among treatments were observed. Carbohydrate intake was associated with increased hepatic transcripts of glucokinase but not of 6-phosphofructokinase. Expression of phosphoenolpyruvate carboxykinase was down-regulated by carbohydrate intake, whereas, unexpectedly, glucose 6-phosphatase was up-regulated. Lipogenic enzyme activities (glucose-6-phosphate dehydrogenase, malic enzyme, fatty acid synthase) and ∆6 fatty acyl desaturase (FADS2) transcripts were increased in liver of fish fed CH+ diets, supporting an enhanced potential for lipogenesis and long-chain PUFA (LC-PUFA) biosynthesis. Despite the lower hepatic cholesterol content in CH+ groups, no influence on the expression of genes related to cholesterol efflux (ATP-binding cassette G5) and biosynthesis (lanosterol 14 α-demethylase, cytochrome P450 51 cytochrome P450 51 (CYP51A1); 7-dehydrocholesterol reductase) was recorded at the hepatic level. At the intestinal level, however, induction of CYP51A1 transcripts by carbohydrate intake was recorded. Dietary VO led to decreased plasma phospholipid and cholesterol concentrations but not on the transcripts of proteins involved in phospholipid biosynthesis (glycerol-3-phosphate acyltransferase) and cholesterol metabolism at intestinal and hepatic levels. Hepatic and muscular fatty acid profiles reflected that of diets, despite the up-regulation of FADS2 transcripts. Overall, this study demonstrated that dietary carbohydrates mainly affected carbohydrate metabolism, lipogenesis and LC-PUFA biosynthesis, whereas effects of dietary lipid source were mostly related with tissue fatty acid composition, plasma phospholipid and cholesterol concentrations, and LC-PUFA biosynthesis regulation. Interactions between dietary macronutrients induced modifications in tissue lipid and glycogen content.
authors.affiliation: 1Departamento de Biologia, Faculdade de Ciências,Universidade do Porto,Rua do Campo Alegre,Edifício FC4,4169-007 Porto,Portugal.
authors.forename: Carolina
authors.identifier: 0000-0002-4246-5741
authors.initials: C
authors.lastname: Castro
authors.affiliation: 3INRA,UR1067 Nutrition Metabolism Aquaculture,F-64310 Saint-Pée-sur-Nivelle,France.
authors.forename: Geneviève
authors.initials: G
authors.lastname: Corraze
authors.affiliation: 1Departamento de Biologia, Faculdade de Ciências,Universidade do Porto,Rua do Campo Alegre,Edifício FC4,4169-007 Porto,Portugal.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Firmino-Diógenes
authors.affiliation: 3INRA,UR1067 Nutrition Metabolism Aquaculture,F-64310 Saint-Pée-sur-Nivelle,France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Larroquet
authors.affiliation: 3INRA,UR1067 Nutrition Metabolism Aquaculture,F-64310 Saint-Pée-sur-Nivelle,France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Panserat
authors.affiliation: 1Departamento de Biologia, Faculdade de Ciências,Universidade do Porto,Rua do Campo Alegre,Edifício FC4,4169-007 Porto,Portugal.
authors.forename: Aires
authors.initials: A
authors.lastname: Oliva-Teles
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004032:Diet / Q000662:veterinary; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000494:pharmacology*; D004041:Dietary Fats; D005786:Gene Expression Regulation; D005947:Glucose / Q000378:metabolism*; D050356:Lipid Metabolism / Q000187:drug effects*; D021541:Sea Bream / Q000378:metabolism*
chemical_list: D004040:Dietary Carbohydrates; D004041:Dietary Fats; D005947:Glucose
keywords: CYP51A1 lanosterol 14 α-demethylase; Carbohydrate content; Cholesterol; FA fatty acid; FAS fatty acid synthase; FO fish oil; Fatty acid bioconversion; G6PD glucose-6-phosphate dehydrogenase; G6Pase glucose 6-phosphatase; LC-PUFA long-chain PUFA; Lipid sources; ME malic enzyme; Nutrient metabolism; PL phospholipids; VO vegetable oil; cytochrome P450 51; elovl5 elongase 5