It was previously shown that the influence of high-energy diets on growth and flesh quality of grass carp was closely related to energy resource. The mechanisms were explored in this study by investigating the hepatic lipid and glucose metabolism of grass carp. Juvenile grass carp (Ctenopharyngodon idella) with initial body weight (55.0 ± 2.5) g were fed with four purified diets for 11 weeks, with four replicates per diet and 20 fish per replicate. Three high-energy diets with high level of carbohydrate, fat and protein were prepared, and their gross energy was 11% higher than that of control diet. Results showed that the highest contents of hepatic crude fat, total saturated fatty acids, n-6 unsaturated fatty acids and glycogen, as well as the highest grade of hepatocyte steatosis were observed in grass carp fed the high-carbohydrate diet. Data on hepatic mRNA expression indicated that the high-carbohydrate diet increased the genes expression including pk, gck, g6pd, fas and acc-1, while the high-fat diet significantly increased the genes expression including pk, gck, fbp, pck, lpl and hsl. The high-fat and high-carbohydrate diets activated hepatic AMPK/ACC pathway, whereas inhibited TOR/SREBP-1 pathway. In conclusion, the high-carbohydrate diet had a stronger effect on the hepatic lipid accumulation than the high-fat diet in grass carp. The acceleration of lipolysis, glycolysis and gluconeogenesis in liver improved the utilization of the high-fat diet in grass carp. Besides, the high-carbohydrate diet can promote hepatic glycolysis and pentose phosphate shunt and inhibit gluconeogenesis in grass carp.

中文翻译：

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草鱼幼鱼肝脏脂质和葡萄糖代谢对高常量营养素日粮的适应性

先前研究表明，高能量日粮对草鱼生长和肉质的影响与能量资源密切相关。本研究通过研究草鱼的肝脏脂质和糖代谢来探索其机制。幼年草鱼 ( Ctenopharyngodon idella) 初始体重 (55.0 ± 2.5) g 用四种纯化饲料喂养 11 周，每种饲料有四个重复，每个重复 20 条鱼。制备了三种碳水化合物、脂肪和蛋白质含量高的高能量日粮，其总能量比对照日粮高11%。结果表明，饲喂高碳水化合物饲料的草鱼肝脏粗脂肪、总饱和脂肪酸、n-6不饱和脂肪酸和糖原含量最高，肝细胞脂肪变性程度最高。肝脏 mRNA 表达数据表明，高碳水化合物饮食增加了基因表达，包括pk、gck、g6pd、fas和acc - 1，而高脂肪膳食显著增加的基因表达，包括PK，GCK，FBP，PCK，LPL和HSL。高脂肪和高碳水化合物饮食激活了肝脏 AMPK/ACC 通路，而抑制了 TOR/SREBP-1 通路。综上所述，高碳水化合物饮食对草鱼肝脏脂质积累的影响比高脂肪饮食更强。肝脏脂肪分解、糖酵解和糖异生的加速提高了草鱼对高脂饲料的利用率。此外，高碳水化合物饮食可促进草鱼肝糖酵解和磷酸戊糖分流，抑制糖异生。