DHA 与 EPA 合成超长链多不饱和脂肪酸的效率比较

目的：比较在ELOVL4蛋白酶催化作用下，DHA和EPA合成超长链多不饱和脂肪酸VLC-PUFA的效率。方法构建携带ELOVL4基因和绿色荧光蛋白的重组腺病毒，转入培养的 PC12细胞，通过qRT-PCR定量分析ELOVL 4基因的表达量，WB检测ELOVL4蛋白的表达；1∶1加入DHA和EPA，孵育48 h之后进行脂肪酸提取，通过气相质谱 GC-MS分析超长链脂肪酸的成分。结果 GC-MS检测到分别用DHA及EPA处理后的PC12＋Ad-ELOVL4的细胞中有n3 VLC-PUFA的表达，34：5n3和36：5n3分别为0.85％和1.11％；34：6n3和36：63n分别为0.16％和0.29％；EPA所产生的五烯酸总和是DHA所产生的六烯酸总和的4倍。结论 EPA合成VLC-PUFA的效率远远高于DHA，为患者提供更高比例的 EPA，而非DHA，可能是治疗STGD3疾病的方式之一。

Comparison of elongatio n efficiency between DHA and EPA in syn thesis of very long chain polyunsaturated fatty acids

Objective To compare the elongation efficiency between DHA and EPA for synthesis of very long chain polyunsat -urated fatty acid （VLC-PUFAs） under catalytic action of ELOVL4 protease.Methods PC12 cells were transduced with recombinant adenovirus type 5 carrying mouse Elovl4 and green fluorescent protein （GFP）.GFP-expressing and non-transduced cells were used as controls.ELOVL4 gene expression was quantified by qRT-PCRs.ELOVL4 protein was analyzed by Western-Blot （WB）.The transduced cells were treated with DHA or EPA （1：1）.After 48 h of incubation,cells were collected,and fatty acid methyl esters were prepared following total lipids extraction .The fatty acid was analyzed by using a gas chromatography-mass spectrometry （ GC-MS） .Results GC-MS analysis showed that the DHA and EPA treated PC 12＋Ad-ELOVL4 had n3 VLC-PUFAs in which 34：5n3 and 36：5n3 were 0.85%and 1.11%,respectively;34：6n3 and 36：6n3 were 0.16% and 0.29%,respectively.Total amount of pentaenoics synthesized from EPA was almost four times than that of hexaenoics synthesized from DHA .Conclusion Elongation efficiency of VLC-PUFAs from EPA is much higher than that from DHA .Therefore,dietary supplementation of more EPA rather than DHA may provide some therapeutic benefits for patients with Stargardts＆#39;disease （STGD3）.