Cook H W
Can J Biochem. 1980 Feb;58(2):121-7. doi: 10.1139/o80-017.
In addition to dietary linoleic acid (cis,cis-18:2), trans isomers of 18:2 may be ingested as minor components of partially hydrogenated oils. Developing rat brain has significant capacity for conversion of cis,cis-18:2 to more abundant polyenes by desaturation and elongation, but less is known about trans dienes. We have shown that incorporation of 1-14C-labeled cis,cis-,cis,trans-, and trans,trans-18:2 into brain lipids of 10-day-old rats is significant but that metabolism of the isomers between 0.2 and 72 h after intracerebral injection differs markedly. Incorporation of trans,trans-18:2 into phosphoglyceride and triacylglycerol was slower than that for cis,cis diene. Oxidation of all isomers occurred with formation of similar quantities of labeled cholesterol and palmitate. However, metabolism of trans dienes differed in two important respects: (i) desaturation and elongation of trans-containing diene was much less (less than 5 versus greater than 30% for cis,cis-18:2 after 6 h); (ii) trans,trans-18:2 and palmitate appeared to be preferentially esterified to the 1 position, whereas cis,cis-18:2 and its products were mainly in the 2 position of choline and ethanolamine phosphoglycerides. Thus, developing brain does not appear to ensure exclusion of trans dienes from membrane lipids; however, conversion by desaturation and elongation and selectivity for position of acylation differ markedly for the cis- and trans-containing dienoic isomers.
除了膳食中的亚油酸（顺，顺-18:2）外，18:2的反式异构体可能作为部分氢化油的次要成分被摄入。发育中的大鼠大脑具有将顺，顺-18:2通过去饱和和延长转化为更丰富的多烯的显著能力，但关于反式二烯的了解较少。我们已经表明，将1-14C标记的顺，顺-、顺，反-和反，反-18:2掺入10日龄大鼠的脑脂质中是显著的，但脑内注射后0.2至72小时内这些异构体的代谢有明显差异。反，反-18:2掺入磷酸甘油酯和三酰甘油的速度比顺，顺二烯慢。所有异构体的氧化都伴随着形成相似量的标记胆固醇和棕榈酸酯。然而，反式二烯的代谢在两个重要方面有所不同：（i）含反式二烯的去饱和和延长程度要低得多（6小时后，反，反-18:2小于5%，而顺，顺-18:2大于30%）；（ii）反，反-18:2和棕榈酸酯似乎优先酯化到1位，而顺，顺-18:2及其产物主要位于胆碱和乙醇胺磷酸甘油酯的2位。因此，发育中的大脑似乎不能确保从膜脂质中排除反式二烯；然而，含顺式和反式二烯异构体的去饱和和延长转化以及酰化位置的选择性有明显差异。
