title: Modulation of appetite, lipid and glucose metabolism of juvenile grass carp (Ctenopharyngodon idellus) by different dietary protein levels.
abstract: This study was undertaken to explore the systemic metabolic strategies of juvenile grass carp (Ctenopharyngodon idellus) to maintain growth when fed with different dietary protein levels. The optimal growth group and two growing discomfort groups were selected through the basic data, to explain the growth difference from appetite regulation and lipid and glucose metabolism perspective. Three experimental diets were formulated with three dietary protein levels at 200.3, 296.1 and 442.9 g kg-1, named P1, P2 and P3, respectively. Juvenile grass carp (initial body weight 12.28 ± 0.14 g) were fed with three diets with 3 replications per dietary treatment in an indoor recirculation system for an 8-week feeding trial. Fish fed with diet P2 dietary group showed significantly higher WG, SGR, FI and PER than other groups. Compared with other groups, mRNA expressions of NPY, Y8a and Y8b in fish fed with P2 significantly down-regulated, while the expressions of CCK and CART in fish fed with P3 significantly down-regulated (P < 0.05). With increasing dietary protein levels, G6Pase, GK, PK and PEPCK were all significantly inhibited (P < 0.05). For lipid metabolism, the mRNA expression of ACC in P1 dietary group was significantly higher than P3 dietary group; besides, LPL expression in P3 group was significantly higher than other two groups (P < 0.05). PPARα expression in P2 was significantly lower than other groups (P < 0.05). These results suggested that grass carp fed with P2 (296.1 g kg-1protein level) showed highest weight gain, contributed to more balanced nutrient metabolism and appetite regulation. Too high dietary protein (442.9 g kg-1) should be avoided because it induced lowest PER, body lipid and liver lipid, and inhibited glucose and lipid metabolism in juvenile grass carp.
authors.affiliation: College of Fisheries, Chinese Perch Research Center, Huazhong Agricultural University, No. 1, Shizishan Street, Hongshan District, Wuhan, 430070, Hubei Province, China.|Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, 430070, China.
authors.forename: Jiao
authors.initials: J
authors.lastname: Li
authors.affiliation: College of Fisheries, Chinese Perch Research Center, Huazhong Agricultural University, No. 1, Shizishan Street, Hongshan District, Wuhan, 430070, Hubei Province, China.|Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, 430070, China.
authors.forename: Liwei
authors.initials: L
authors.lastname: Liu
authors.affiliation: College of Fisheries, Chinese Perch Research Center, Huazhong Agricultural University, No. 1, Shizishan Street, Hongshan District, Wuhan, 430070, Hubei Province, China. xufang_liang@hotmail.com.|Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, 430070, China. xufang_liang@hotmail.com.
authors.forename: Xu-Fang
authors.initials: XF
authors.lastname: Liang
authors.affiliation: College of Fisheries, Chinese Perch Research Center, Huazhong Agricultural University, No. 1, Shizishan Street, Hongshan District, Wuhan, 430070, Hubei Province, China.|Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, 430070, China.
authors.forename: Xiaochen
authors.initials: X
authors.lastname: Yuan
authors.affiliation: College of Fisheries, Chinese Perch Research Center, Huazhong Agricultural University, No. 1, Shizishan Street, Hongshan District, Wuhan, 430070, Hubei Province, China.|Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, 430070, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.affiliation: College of Fisheries, Chinese Perch Research Center, Huazhong Agricultural University, No. 1, Shizishan Street, Hongshan District, Wuhan, 430070, Hubei Province, China.|Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, 430070, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Li
authors.affiliation: College of Fisheries, Chinese Perch Research Center, Huazhong Agricultural University, No. 1, Shizishan Street, Hongshan District, Wuhan, 430070, Hubei Province, China.
authors.forename: Qingchao
authors.initials: Q
authors.lastname: Wang
authors.affiliation: College of Fisheries, Chinese Perch Research Center, Huazhong Agricultural University, No. 1, Shizishan Street, Hongshan District, Wuhan, 430070, Hubei Province, China.|Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, 430070, China.
authors.forename: Jinguang
authors.initials: J
authors.lastname: Fang
authors.affiliation: National Aquafeed Safety Assessment Station, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
authors.forename: Min
authors.initials: M
authors.lastname: Xue
authors.affiliation: National Aquafeed Safety Assessment Station, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Wang
mesh_terms: D000818:Animals; D001066:Appetite; D001921:Brain / Q000378:metabolism; D002347:Carps / Q000378:metabolism*; D004044:Dietary Proteins / Q000494:pharmacology*; D029941:Fish Proteins / Q000235:genetics; D005786:Gene Expression Regulation; D005947:Glucose / Q000378:metabolism*; D050356:Lipid Metabolism; D008099:Liver / Q000378:metabolism; D009478:Neuropeptide Y / Q000235:genetics; D009842:Oligopeptides / Q000235:genetics
chemical_list: D004044:Dietary Proteins; D029941:Fish Proteins; D009478:Neuropeptide Y; D009842:Oligopeptides; C062384:tyrosyl-leucyl-phenylalanyl-glutaminyl-prolyl-glutaminyl-arginyl-phenylalaninamide; D005947:Glucose
keywords: Appetite; Ctenopharyngodon idellus; Dietary protein level; Glucose metabolism; Growth; Lipid metabolism