Zambonino Infante J L, Cahu C L
Unité Mixte de Nutrition des Poissons IFREMER-INRA, 29280 Plouzané, France.
J Nutr. 1999 Jun;129(6):1195-200. doi: 10.1093/jn/129.6.1195.
This study was designed to determine the nutritional lipid requirement of seabass larvae and to understand the effects of dietary fat concentration on their digestive tract maturation. Seabass (Dicentrarchus labrax) larvae were fed, from d 15 to 38 of life, one of five isonitrogenous compound diets with different lipid levels, ranging from 10 to 30 g/100 g. The higher the lipid level, the greater the growth and survival of the larvae (P < 0.05). The lipolytic enzymes assayed, lipase and phospholipase A2, were stimulated by the increase in their respective dietary substrates, triglycerides and phospholipids, in 38-d-old larvae (P < 0.05). Nevertheless, a plateau in the activity of these two lipolytic enzymes was observed from 20% dietary lipids onwards. The similar mRNA levels of phospholipase A2 in the three groups fed the highest lipid levels suggested that the maximal synthesis level of lipolytic enzyme was reached at 20% dietary fat. Pancreatic secretion of trypsin and amylase were positively affected by the dietary lipid level; a possible involvement of a cholecystokinin-releasing factor is discussed. Diets containing >20% lipids led to the increase in activities of brush border membrane enzymes to the detriment of a cytosolic enzyme in enterocytes, leucine-alanine (Leu-Ala) peptidase. This enzymatic change reveals the earlier maturation of enterocytes in larva groups fed high lipid levels.
本研究旨在确定海鲈幼鱼的营养性脂质需求，并了解日粮脂肪浓度对其消化道成熟的影响。在海鲈（欧洲鲈）幼鱼出生后的第15至38天，用五种不同脂质水平（10至30克/100克）的等氮复合日粮之一进行投喂。脂质水平越高，幼鱼的生长和存活率越高（P<0.05）。在38日龄的幼鱼中，所检测的脂解酶（脂肪酶和磷脂酶A2）受到各自日粮底物（甘油三酯和磷脂）增加的刺激（P<0.05）。然而，从日粮脂质含量达到20%起，这两种脂解酶的活性出现了平台期。在投喂最高脂质水平的三组中，磷脂酶A2的mRNA水平相似，这表明在日粮脂肪含量为20%时达到了脂解酶的最大合成水平。日粮脂质水平对胰蛋白酶和淀粉酶的胰腺分泌有积极影响；文中讨论了胆囊收缩素释放因子可能发挥的作用。脂质含量>20%的日粮导致肠刷状缘膜酶活性增加，同时损害了肠细胞中的一种胞质酶——亮氨酸-丙氨酸（Leu-Ala）肽酶。这种酶活性的变化表明，在投喂高脂日粮的幼鱼组中，肠细胞成熟较早。
