Journal Article

Link between lipid metabolism and voluntary food intake in rainbow trout fed coconut oil rich in medium-chain TAG

Kaushik, Sadasivam, Médale, Françoise, Geurden, Inge, Terrier, Frédéric, Schrama, Johan W., Figueiredo-Silva, A. Cláudia

2012

Overview

We examined the long-term effect of feeding coconut oil (CO; rich in lauric acid, C12) on voluntary food intake and nutrient utilisation in rainbow trout (Oncorhynchus mykiss), with particular attention to the metabolic use (storage or oxidation) of ingested medium-chain TAG. Trout were fed for 15 weeks one of the four isoproteic diets containing fish oil (FO) or CO as fat source (FS), incorporated at 5 % (low fat, LF) or 15 % (high fat, HF). Fat level or FS did not modify food intake (g/kg0·8 per d), despite higher intestinal cholecystokinin-T mRNA in trout fed the HF-FO diet. The HF diets relative to the LF ones induced higher growth and adiposity, whereas the replacements of FO by CO resulted in similar growth and adiposity. This, together with the substantial retention of C12 (57 % of intake), suggests the relatively low oxidation of ingested C12. The down-regulation of carnitine palmitoyl-transferase-1 (CPT-1) confirms the minor dependency of medium-chain fatty acids (MCFA) on CPT-1 to enter the mitochondria. However, MCFA did not up-regulate mitochondrial oxidation evaluated using hepatic hydroxyacyl-CoA dehydrogenase as a marker, in line with their high retention in body lipids. At a low lipid level, MCFA increased mRNA levels of fatty acid synthase, elongase and stearoyl-CoA desaturase in liver, showing the hepatic activation of fatty acid synthesis pathways by MCFA, reflected by increased 16 : 0, 18 : 0, 16 : 1, 18 : 1 body levels. The high capacity of trout to incorporate and transform C12, rather than to readily oxidise C12, contrasts with data in mammals and may explain the absence of a satiating effect of CO in rainbow trout.

• Publisher: Cambridge University Press,CCSD,Cambridge University Press (CUP)
• Subject: Adiposity / Animals / Aquaculture / Behaviour, Appetite and Obesity / Biological and medical sciences / carnitine / Carnitine O-Palmitoyltransferase - genetics / Carnitine O-Palmitoyltransferase - metabolism / Cholecystokinin - genetics / Cholecystokinin - metabolism / Coconut Oil / Computer Science / cromileptes-altivelis / Diet / Diet, Fat-Restricted - veterinary / Diet, High-Fat - veterinary / dodecanoic acid / drum sciaenops-ocellatus / Eating / energy-intake / Fatty Acid Synthases - genetics / Fatty Acid Synthases - metabolism / Fatty acids / fatty-acid synthase / fatty-acid-composition / feed-intake / Feeding. Feeding behavior / Fish / Fish oils / Fish Proteins - genetics / Fish Proteins - metabolism / Food / food intake / Fundamental and applied biological sciences. Psychology / Gene Expression Regulation, Developmental / Lauric Acids - administration & dosage / Lauric Acids - adverse effects / Lauric Acids - analysis / Lauric Acids - metabolism / Life Sciences / Lipid Metabolism / Lipids / liver / Liver - enzymology / Liver - metabolism / long term effects / mammals / messenger RNA / Metabolism / mitochondria / Muscle, Skeletal - enzymology / Muscle, Skeletal - metabolism / nutrient intake / Nutrient utilization / Oils & fats / Oncorhynchus mykiss / Oncorhynchus mykiss - growth & development / Oncorhynchus mykiss - metabolism / Oxidation / Oxidative Phosphorylation / Plant Oils - administration & dosage / Plant Oils - adverse effects / Plant Oils - chemistry / Plant Oils - metabolism / plasma cholecystokinin / polka-dot grouper / Retention / RNA, Messenger - metabolism / Salmon / salmon salmo-salar / satiety / stearoyl-CoA desaturase / tissue distribution / trout / Vertebrates: anatomy and physiology, studies on body, several organs or systems / Weight Gain
• ISBN: 0003048873000