PDF(Pubmed)
Abstract：
An 8-week feeding trial was conducted in Pacific white shrimp (Litopenaeus vannamei) to evaluate the effects of dietary choline supplementation on choline transport and metabolism, hepatopancreas histological structure and fatty acid profile, and regulation of lipid metabolism. Six isonitrogenous and isolipidic diets were formulated to contain different choline levels of 2.91 (basal diet), 3.85, 4.67, 6.55, 10.70 and 18.90 g/kg, respectively. A total of 960 shrimp (initial weight, 1.38 ± 0.01 g) were distributed randomly into twenty-four 250-L cylindrical fiber-glass tanks, with each diet assigned randomly to 4 replicate tanks. The results indicated that dietary choline significantly promoted the deposition of choline, betaine and carnitine (P < 0.05). The diameters and areas of R cells, total lipid and triglyceride contents in hepatopancreas, and triglyceride and non-esterified fatty acid contents in hemolymph were negatively correlated with dietary choline level. The contents of functional fatty acids in hepatopancreas, the activity of acetyl-CoA carboxylase (Acc), and the mRNA expression of fas, srebp and acc were highest in shrimp fed the diet containing 4.67 g/kg choline, and significantly higher than those fed the diet containing 2.91 g/kg, the lowest level of choline (P < 0.05). The number of R cells, content of very low-density lipoprotein (VLDL), activities of carnitine palmitoyl-transferase (Cpt1), lipoprotein lipase and hepatic lipase, and the mRNA expression levels of cpt1, fabp, fatp, ldlr, and ampk in hepatopancreas increased significantly as dietary choline increased (P < 0.05). In addition, hepatopancreas mRNA expression levels of ctl1, ctl2, oct1, badh, bhmt, ck, cept, and cct were generally up-regulated as dietary choline level increased (P < 0.01). In conclusion, dietary choline promoted the deposition of choline and its metabolites by up-regulating genes related to choline transport and metabolism. Moreover, appropriate dietary choline level promoted the development of hepatopancreas R cells and maintained the normal accumulation of lipids required for development, while high dietary choline not only promoted hepatopancreas lipid export by enhancing VLDL synthesis, but also promoted fatty acid β-oxidation and inhibited de novo fatty acid synthesis by activating the Ampk/Srebp signaling pathway. These findings provided further insight and understanding of the mechanisms by which dietary choline regulated lipid metabolism in L. vannamei.
摘要：
在太平洋白虾（凡纳滨对虾）中进行了为期8周的喂养试验，以评估日粮补充胆碱对胆碱转运和代谢的影响，肝胰腺组织学结构和脂肪酸谱，和调节脂质代谢。配制了六种同氮和异碘饮食，使其含有不同的胆碱水平为2.91（基础饮食），3.85、4.67、6.55、10.70和18.90g/kg，分别。共960只虾(初始重量，1.38±0.01g）随机分配到二十四个250升圆柱形玻璃纤维罐中，每个饮食随机分配到4个重复的坦克。结果表明,饲粮胆碱显著促进胆碱的沉积,甜菜碱和肉碱(P<0.05)。R细胞的直径和面积，肝胰腺中的总脂质和甘油三酯含量，血淋巴中甘油三酯和非酯化脂肪酸含量与饲粮胆碱水平呈负相关。肝胰腺中功能性脂肪酸的含量,乙酰辅酶A羧化酶（Acc）的活性，和Fas的mRNA表达，饲喂含4.67g/kg胆碱的虾中srepp和acc最高，显着高于饲喂含2.91g/kg的饮食的饮食，胆碱水平最低(P<0.05)。R细胞的数量，极低密度脂蛋白（VLDL）的含量，肉碱棕榈酰转移酶（Cpt1）的活性，脂蛋白脂肪酶和肝脂酶，以及cpt1、fabp、fatp,ldlr,随着饲粮胆碱的增加，肝胰腺中的ampk显着增加（P<0.05）。此外,肝胰腺ctl1、ctl2、oct1、badh、bhmt,ck,cept,随着饲粮胆碱水平的升高，cct普遍上调（P<0.01）。总之,膳食胆碱通过上调与胆碱转运和代谢相关的基因促进胆碱及其代谢产物的沉积。此外，适当的膳食胆碱水平促进肝胰腺R细胞的发育并维持发育所需的脂质的正常积累，而高膳食胆碱不仅通过增强VLDL合成促进肝胰腺脂质输出，而且还通过激活Ampk/Srepp信号通路促进脂肪酸β氧化并抑制脂肪酸从头合成。这些发现为膳食胆碱调节凡纳滨对虾脂质代谢的机制提供了进一步的见解和理解。
