EFFECTS OF DIETARY LINOLENATE ON ARACHIDONATE

这项研究的目的是评估膳食营养素的功效。 亚麻酸（18：3 n-3），与二十碳五烯酸（20：5 n-3）相比，或 二十二碳六烯酸（22：6 n-3），其在鱼油中丰富，以抑制 花生四烯酸（20：4 n-6）在大鼠体内形成类花生酸 组织中 20：5 n-3在降低 血栓形成的可能性被认为主要是由于其 竞争性抑制20：4 n-6转化为血栓烷A2 （TXA 2），并通过置换降低血小板中的20：4 n-6水平。 一个重要的问题是，另一种类型的饮食是否 n-3脂肪酸可以达到类似或甚至更有益的效果， 20：5n-3。 本申请人提出，膳食18：3 n-3抑制 将亚油酸（18：3 n-6）转化为20：4 n-6。 它还抑制了 形成20：4 n-6的环加氧酶衍生产物。 此外，委员会认为， 18：3 n-3不是白三烯（LT）的底物，而20：5 n-3是白三烯的底物。 导致五烯形成的5-脂氧合酶的优选底物 LTS. 因此，膳食18：3 n-3可能是比20：5 n-3更有效的抑制剂。 3为LT的生物合成。 具体的目的是比较18：3 n-3与 20：5 n-3或22：6 n-3对类二十烷酸前体水平的影响 游离脂肪酸级分和组织磷脂中的脂肪酸，和（2） 在组织中形成20：4 n-6和20：5 n-3来源的类二十烷酸。 大鼠将在24小时内喂食分级量的纯化的18：3 n-3、20：5 n-3或22：6 n-3。 持续12周存在恒定量的18：2n-6。 花生酸 将通过放射免疫测定法测定组织中合成的 免疫层析测定。 长远目标是建立 我们饮食中的n-3与n-6脂肪酸的理想比例，以减少某些 冠心病的风险。 目前，大多数饮食指南使用 多不饱和脂肪酸（PUFA），不区分PUFA类型 (n-3或n-6）。 今后，这一比例可能需要在 饮食指南。

The objective of the proposed study is to evaluate the efficacy of dietary linolenic acid (18:3n-3), as compared to eicosapentaenoic acid (20:5n-3) or docosahexaenoic acid (22:6n-3) which are abundant in fish oil, to inhibit the formation of eicosanoids derives from arachidonic acid (20:4n-6) in rat tissues. The suggested beneficial effects of 20:5n-3 in reducing thrombogenic potential are considered to be primarily due to its competitive inhibition of the conversion of 20:4n-6 to thromboxane A2 (TXA2), and reduction of the 20:4n-6 level in platelets by displacement. An important question can be raised as to whether another type of dietary n-3 fatty acid can achieve similar or even more beneficial effects than 20:5n-3. This applicant proposes that dietary 18:3n-3 inhibits the conversion of linoleic acid (18:3n-6) to 20:4n-6. It also inhibits the formation of cyclooxygenase-derived products of 20:4n-6. Furthermore, 18:3n-3 is not a substrate for leukotrienes (LT), whereas 20:5n-3 is a preferred substrate for 5-lipoxygenase leading to the formation of pentaene LTs. Thus, dietary 18:3n-3 may be a more effective inhibitor than 20:5n- 3 for the biosynthesis of LTs. The specific aim is to compare 18:3n-3 with 20:5n-3 or 22:6n-3 for its effects on: (1) levels of eicosanoid precursor acids in free fatty acid fractions and tissue phospholipids, and (2) the formation of eicosanoids derived both from 20:4n-6 and 20:5n-3 in tissues. Rats will be fed graded amounts of purified 18:3n-3, 20:5n-3 or 22:6n-3 in the presence of a constant amount of 18:2n-6 for 12 weeks. Eicosanoids synthesized in tissues will be determined by radioimmunoassay and immunochromatographic assay. The long term objective is to establish the desirable ratio of n-3 to n-6 fatty acids in our diets to reduce certain risks of coronary heart disease. Presently, most dietary guidelines use polyunsaturated fatty acids (PUFA) without differentiating types of PUFA (n-3 or n-6). In the future, this ratio may need to be specified in the dietary guidelines.