title: Systemic regulation of L-carnitine in nutritional metabolism in zebrafish, Danio rerio.
abstract: Excess fat accumulation has been observed widely in farmed fish; therefore, efficient lipid-lowering factors have obtained high attention in the current fish nutrition studies. Dietary L-carnitine can increase fatty acid β-oxidation in mammals, but has produced contradictory results in different fish species. To date, the mechanisms of metabolic regulation of L-carnitine in fish have not been fully determined. The present study used zebrafish to investigate the systemic regulation of nutrient metabolism by dietary L-carnitine supplementation. L-carnitine significantly decreased the lipid content in liver and muscle, accompanied by increased concentrations of total and free carnitine in tissues. Meanwhile, L-carnitine enhanced mitochondrial β-oxidation activities and the expression of carnitine palmitoyltransferase 1 mRNA significantly, whereas it depressed the mRNA expression of adipogenesis-related genes. In addition, L-carnitine caused higher glycogen deposition in the fasting state, and increased and decreased the mRNA expressions of gluconeogenesis-related and glycolysis-related genes, respectively. L-carnitine also increased the hepatic expression of mTOR in the feeding state. Taken together, dietary L-carnitine supplementation decreased lipid deposition by increasing mitochondrial fatty acid β-oxidation, and is likely to promote protein synthesis. However, the L-carnitine-enhanced lipid catabolism would cause a decrease in glucose utilization. Therefore, L-carnitine has comprehensive effects on nutrient metabolism in fish.
authors.affiliation: Laboratory of Aquaculture Nutrition and Environmental Health (LANEH), School of Life Sciences, East China Normal University, Shanghai, China.
authors.forename: Jia-Min
authors.initials: JM
authors.lastname: Li
authors.affiliation: Laboratory of Aquaculture Nutrition and Environmental Health (LANEH), School of Life Sciences, East China Normal University, Shanghai, China.
authors.forename: Ling-Yu
authors.initials: LY
authors.lastname: Li
authors.affiliation: Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Qin
authors.affiliation: Laboratory of Aquaculture Nutrition and Environmental Health (LANEH), School of Life Sciences, East China Normal University, Shanghai, China.
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Ning
authors.affiliation: Laboratory of Aquaculture Nutrition and Environmental Health (LANEH), School of Life Sciences, East China Normal University, Shanghai, China.
authors.forename: Dong-Liang
authors.initials: DL
authors.lastname: Lu
authors.affiliation: Laboratory of Aquaculture Nutrition and Environmental Health (LANEH), School of Life Sciences, East China Normal University, Shanghai, China.
authors.forename: Dong-Liang
authors.initials: DL
authors.lastname: Li
authors.affiliation: Laboratory of Aquaculture Nutrition and Environmental Health (LANEH), School of Life Sciences, East China Normal University, Shanghai, China.
authors.forename: Mei-Ling
authors.initials: ML
authors.lastname: Zhang
authors.affiliation: Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Laboratory of Aquaculture Nutrition and Environmental Health (LANEH), School of Life Sciences, East China Normal University, Shanghai, China.
authors.forename: Zhen-Yu
authors.initials: ZY
authors.lastname: Du
mesh_terms: D000818:Animals; D002331:Carnitine / Q000378:metabolism / Q000494:pharmacology*; D002334:Carnitine O-Palmitoyltransferase / Q000235:genetics / Q000378:metabolism; D019587:Dietary Supplements; D005943:Gluconeogenesis / Q000235:genetics; D006003:Glycogen / Q000378:metabolism; D006019:Glycolysis / Q000235:genetics; D050356:Lipid Metabolism / Q000187:drug effects*; D015227:Lipid Peroxidation / Q000187:drug effects; D008099:Liver / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D009132:Muscles / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D015027:Zebrafish / Q000378:metabolism*
chemical_list: D006003:Glycogen; D002334:Carnitine O-Palmitoyltransferase; D058570:TOR Serine-Threonine Kinases; D002331:Carnitine