Effects of conjugated linolenic acids on lipid metabolism and immune functions in rats.

共轭亚麻酸（CLN）是一种脂肪酸，具有18个碳原子和三个共轭双键，由多个位置和几何（顺式（c）和反式（t））异构体组成。共轭亚油酸（CLA）是共轭脂肪酸的代表，在啮齿类动物中已被证明具有降低体脂的作用。我们先前证明，膳食CLN的体脂减少效果至少与CLA相当，甚至比CLA更强。研究中使用的CLN是通过碱异构化制备的，并且是共轭二烯和共轭三烯的混合物。目前尚不清楚合成CLN的影响是否是所有CLN异构体共同的，还是对某些特定异构体负责。在自然界中，一些种子油含有特定类型的CLN作为主要脂肪酸组分。苦瓜、石榴、梓和金盏花分别含有α-桐酸（9 c，11 t，13 t-18：3）、石榴酸（9 c，11 t，13 c-18：3）、梓酸（9 t，11 t，13 c-18：3）和金盏花酸（8 t，10 t，12 c-18：3）。在这个项目中，我们检查了这些种子油中的CLN是否降低了雄性SD大鼠的脂肪组织重量。含有α-亚麻酸（LN）的亚麻籽油用作对照脂肪。经过4周的饮食含有0.7%的这些脂肪，饮食石榴酸（石榴油）降低，而其他CLN没有降低肾周脂肪组织的重量相比，LN。此外，石榴酸增加了肝线粒体β-氧化的活性。在预先喂饲高脂（20%猪油）饲料4周的大鼠中也部分观察到这种效应。因此，这表明石榴油中的石榴酸至少是减少大鼠脂肪组织重量的因素之一。本研究还测定了血清免疫球蛋白（IG）A、IgG、IgM和IgE的浓度。然而，饮食脂肪依赖性影响不显著。

Conjugated linolenic acid (CLN) is a fatty acid that has 18 carbons with three conjugated double bonds composed of multiple positional and geometric (cis(c) and trans(t)) isomers. Conjugated linoleic acid (CLA), the representative conjugated fatty acid has been shown to reduce body fat in rodents. We previously demonstrated that body fat reducing effect of dietary CLN is at least comparable or even stronger than that of CLA in rats. The CLN used in the study was prepared by alkaline isomerization, and was a mixture of conjugated diene and conjugated triene. It is not clear whether the effects of synthetic CLN are common to all CLN isomers or responsible to some specific isomers. In nature, some seed oil contains a particular type of CLN as a main fatty acid component. Bitter gourd, pomegranate, catalpa and pot marigold contain alpha-eleostearic acid (9c,11t,13t-18:3), punicic acid (9c,11t,13c-18:3), catalpic acid (9t,11t,13c-18:3), and calendic acid (8t,10t,12c-18:3), respectively. In this project, we examined whether the CLN in these seed oils reduced the adipose tissue weights in male SD rats. Linseed oil containing alpha-linolenic acid (LN) was used as a control fat. After 4 wk on diets containing 0.7% of these fats, dietary punicic acid (pomegranate oil) lowered, whereas the other CLNs did not lower the weight of perirenal adipose tissue as compared with LN. Also, punicic acid increased the activity of hepatic beta-oxidation in mitochondria. This effect was also partly observed in rats pre-fed with the high-fat (20% lard) diet for 4 wk. It was, therefore, suggested that punicic acid in pomegranate oil was at least one of the factors for reducing adipose tissue weight in rats. In this study, we also measured serum concentration of immunoglobulin (Ig) A, IgG, IgM and IgE. However, the dietary fat-dependent effect was not significant.