title: Hepatic β-oxidation and regulation of carnitine palmitoyltransferase (CPT) I in blunt snout bream Megalobrama amblycephala fed a high fat diet.
abstract: High-fat diets may promote growth, partly through their protein-sparing effects. However, high-fat diets often lead to excessive fat deposition, which may have a negative impact on fish such as poor growth and suppressive immune. Therefore, this study investigated the effects of a fat-rich diet on the mechanisms of fat deposition in the liver. Three-hundred blunt snout bream (Megalobrama amblycephala) juveniles (initial mass 18.00 ± 0.05 g) were fed with one of two diets (5% or 15% fat) for 8 weeks. β-Oxidation capacity and regulation of rate-limiting enzymes were assessed. Large fat droplets were present in hepatocytes of fish fed the high-fat diet. This observation is thought to be largely owing to the reduced capacity for mitochondrial and peroxisomal β-oxidation in the livers of fish fed the high-fat diet, as well as the decreased activities of carnitine palmitoyltransferase (CPT) I and acyl-CoA oxidase (ACO), which are enzymes involved in fatty-acid metabolism. Study of CPT I kinetics showed that CPT I had a low affinity for its substrates and a low catalytic efficiency in fish fed the high-fat diet. Expression of both CPT I and ACO was significantly down-regulated in fish fed the high-fat diet. Moreover, the fatty-acid composition of the mitochondrial membrane varied between the two groups. In conclusion, the attenuated β-oxidation capacity observed in fish fed a high-fat diet is proposed to be owing to decreased activity and/or catalytic efficiency of the rate-limiting enzymes CPT I and ACO, via both genetic and non-genetic mechanisms.
authors.affiliation: College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu province, People's Republic of China.
authors.forename: Kang-Le
authors.initials: KL
authors.lastname: Lu
authors.affiliation: College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu province, People's Republic of China.
authors.forename: Wei-Na
authors.initials: WN
authors.lastname: Xu
authors.affiliation: College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu province, People's Republic of China.
authors.forename: Li-Na
authors.initials: LN
authors.lastname: Wang
authors.affiliation: College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu province, People's Republic of China.
authors.forename: Ding-Dong
authors.initials: DD
authors.lastname: Zhang
authors.affiliation: College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu province, People's Republic of China.
authors.forename: Chun-Nuan
authors.initials: CN
authors.lastname: Zhang
authors.affiliation: College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu province, People's Republic of China.
authors.forename: Wen-Bin
authors.initials: WB
authors.lastname: Liu
mesh_terms: D042962:Acyl-CoA Oxidase / Q000378:metabolism; D000818:Animals; D002334:Carnitine O-Palmitoyltransferase / Q000378:metabolism*; D059305:Diet, High-Fat; D004789:Enzyme Activation; D005227:Fatty Acids / Q000378:metabolism*; D005399:Fishes / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D022781:Hepatocytes / Q000378:metabolism / Q000648:ultrastructure; D007700:Kinetics; D050356:Lipid Metabolism / Q000235:genetics; D008099:Liver / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000378:metabolism; D010084:Oxidation-Reduction; D020675:Peroxisomes / Q000378:metabolism
chemical_list: D005227:Fatty Acids; D042962:Acyl-CoA Oxidase; D002334:Carnitine O-Palmitoyltransferase