Ganga R, Bell J G, Montero D, Robaina L, Caballero M J, Izquierdo M S
Grupo de Investigación en Acuicultura. ULPGC & ICCM. P.O. Box 56, 35200, Telde, Las Palmas, Canary Islands, Spain.
Comp Biochem Physiol B Biochem Mol Biol. 2005 Dec;142(4):410-8. doi: 10.1016/j.cbpb.2005.09.010. Epub 2005 Oct 28.
The aim of this study was to investigate the effects of different levels of substitution of fish oil by vegetable oils rich in oleic, linoleic and linolenic acids on gilthead seabream plasma and leukocyte fatty acid compositions and prostaglandin (PG) and leptin production. Juvenile seabream of 24 g initial body mass were fed four iso-energetic and iso-proteic experimental diets for 281 days. Fatty acid composition of plasma lipids was markedly affected by the inclusion of vegetable oils (VO). ARA (arachidonate), EPA (eicosapentaenoate) and DHA (docosahexaenoate) were preferentially incorporated into polar lipids of plasma, and DHGLA (di-homogammalinoleate) accumulated with increased vegetable oil inclusion. Dietary treatments resulted in alterations of DHGLA/ARA ratios, but not ARA/EPA. ARA-derived PGE(2) production in plasma was not affected by vegetable oils, in agreement with similar eicosanoid precursor ratio (ARA/EPA) in leukocytes total lipids and plasma phospholipids among fish fed with the different dietary treatments. Feeding vegetable oils leads to a decrease in plasma EPA which in turn reduced plasma PGE(3) concentration. Moreover, PGE(3) was the major prostaglandin produced in plasma of fish fed fish oil based diet. Such findings point out the importance of EPA as a precursor of prostaglandins in marine fish, at least for the correct function of the blood cells, and correlates well with the predominant role of this fatty acid in immune regulation in this species. A negative correlation was found between plasma PGE(2) and leptin plasma concentration, suggesting that circulating levels of leptin may act as a metabolic signal modulating PGE(2) release. The present study has shown that increased inclusion of vegetable oils in diet for gilthead seabream may profoundly affect the fatty acid composition of plasma and leukocytes, specially HUFA (highly unsaturated fatty acids), and consequently the production of PGE(3), which can be a major PG in plasma. Alteration in the amount and type of PG produced can be at least partially responsible for the changes in the immune system and health parameters of fish fed diets with high inclusion of VO.
本研究的目的是调查富含油酸、亚油酸和亚麻酸的植物油对金头鲷血浆和白细胞脂肪酸组成以及前列腺素（PG）和瘦素产生的不同替代水平的影响。初始体重为24克的幼龄金头鲷投喂四种等能量和等蛋白的实验饲料，为期281天。植物油（VO）的添加显著影响血浆脂质的脂肪酸组成。花生四烯酸（ARA）、二十碳五烯酸（EPA）和二十二碳六烯酸（DHA）优先掺入血浆的极性脂质中，二高-γ-亚麻酸（DHGLA）随着植物油添加量的增加而积累。日粮处理导致DHGLA/ARA比值发生变化，但ARA/EPA未变。血浆中ARA衍生的PGE(2)产生不受植物油影响，这与不同日粮处理的鱼白细胞总脂质和血浆磷脂中类二十烷酸前体比例（ARA/EPA）相似一致。投喂植物油导致血浆EPA降低，进而降低血浆PGE(3)浓度。此外，PGE(3)是投喂鱼油日粮的鱼血浆中产生的主要前列腺素。这些发现指出了EPA作为海鱼中前列腺素前体的重要性，至少对于血细胞的正常功能而言，并且与该脂肪酸在该物种免疫调节中的主要作用密切相关。发现血浆PGE(2)与血浆瘦素浓度之间呈负相关，表明瘦素的循环水平可能作为调节PGE(2)释放的代谢信号。本研究表明，金头鲷日粮中植物油添加量的增加可能会深刻影响血浆和白细胞的脂肪酸组成，特别是高度不饱和脂肪酸（HUFA），从而影响PGE(3)的产生，PGE(3)可能是血浆中的主要PG。所产生的PG的数量和类型的改变至少可以部分解释高VO添加量日粮喂养的鱼免疫系统和健康参数的变化。
