Adaptation of AMPK-mTOR-signal pathways and lipid metabolism in response to low- and high-level rapeseed meal diet in Chinese perch (Siniperca chuatsi)

Abstract

It is well known that carnivorous fish cannot use plant-proteins efficiently. They affect lipid metabolism of fish and cause serious problems to fish health. The reasons for this deficiency of fish metabolism are not known well. Chinese perch, a carnivorous fish, can accept artificial diet after domestication and is also considered as a novel model of fish for nutrition studies. Therefore, the aim of this study was to explore the effect of fish meal replacement by low-or high-rapeseed meal on lipid and glucose metabolism of Chinese perch. Three experimental diets were formulated with 0, 10%, and 30% rapeseed meal, named as Control, RSL, and RSH groups, respectively. After 8-weeks of the feeding trial, the inhibition of growth and fat deposition were observed in Chinese perch fed with rapeseed meal diets compared to the control group. Fish fed with RSL diets showed decreased food intake, serum low density lipoprotein (LDL), phosphorylated Grb10 (P < 0.05), inhibited fatty acid (FA) transport (lipoprotein lipase (LPL)), and glycerol synthesis (phosphoenol pyruvate carboxykinase (PEPCK)) in the liver. In addition, fish fed with RSL diets were also inhibited FA synthesis (fatty acid synthase (FAS), sterol regulatory element binding protein 1 (SREBP1), and Acetyl-CoA carboxylase (ACC1)), lipid uptake (hepatic lipase (HL)), β-oxidation (carnitine palmitoyltransferase I (CPT1)), and glycerol synthesis (PEPCK) in the visceral adipose tissue. Fish fed with RSH diets showed phosphorylated AMPK, inhibited FA synthesis (SREBP1, ACC1, and FAS), while enhanced lipolysis (hormone-sensitive lipase (HSL)), and then reduced Acetyl-CoA pool. In turn, β-oxidation (peroxisome proliferator-activated receptor-a (PPARα) and CPT1) was inhibited, while glycolysis (glucose-6-phosphatase (G6PD) and pyruvate carboxylase (PC)) were enhanced, consequently the lipid accumulation was decreased in the liver. Fish were also inhibited lipid uptake (LPL), that caused inhibiting of FA synthesis (SREBP1), β-oxidation (CPT1), glycerol synthesis (PEPCK), and in turn improved lipolysis (HSL) in the visceral adipose tissue. Our study suggested that both RSL and RSH diets decreased lipid accumulation in Chinese perch; however, the mechanism of lipid metabolism was different. Fish accepted less diet in RSL group, which inhibited lipid metabolism in the liver and in the visceral adipose tissues, while fish in RSH group activated AMPK pathway, inhibited FA synthesis, and enhanced lipolysis, which reduced Acetyl-CoA pool in the liver. Subsequently, lipid uptake and metabolism were inhibited in the visceral adipose tissue of RSH fish.

Muscle Nutritive Metabolism Changes after Dietary Fishmeal Replaced by Cottonseed Meal in Golden Pompano (Trachinotus ovatus)

“…However, for lipid metabolism, less than 60% of the CSM replacement did not alter the mRNA expression levels of FAS, AGPAT3 and SREBP1. A similar observation could be found in the study of soy bean protein for cod Gadus morhua [ 59 ] and rapeseed meal diet for Chinese perch Siniperca chuatsi [ 60 ]. Furthermore, our recent study on largemouth bass ( Micropterus salmoides ) also presented that the glucose metabolism was more sensitive to feed compositions [ 61 ].…”

Effects of Hydroxylated Lecithin on Growth Performance, Serum Enzyme Activity, Hormone Levels Related to Lipid Metabolism and Meat Quality in Jiangnan White Goslings

“…LEP in poultry can regulate lipid metabolism in the organism by exciting the sympathetic nervous system ( 46 , 47 ). Li et al ( 48 ) found that LEP could inhibit lipid synthesis in hepatocytes, promote hepatocyte lipolysis and lipid deposition in Siniperca chuatsi under a high-fat feeding environment; Lin et al ( 49 ) found that LEP could improve insulin resistance and increase insulin sensitivity in rats, and Steinberg Greg and Dyck ( 50 ) found that the LEP content decrease accelerated the lipid metabolism in obese rats caused by high-fat diets. In this study, except for HLG50, the LEP contents in the treated groups were significantly decreased, indicating that the hydroxylated lecithin and soy lecithin can reduce LEP content to promote lipid metabolism, making the goslings produce foraging behavior, which was consistent with the above study results.…”