Blond J P, Lemarchal P
Reprod Nutr Dev (1980). 1984;24(1):1-10. doi: 10.1051/rnd:19840101.
The effects of alpha-linolenic acid on delta 5 desaturation of 20: 3 n-6 dihomo-gamma-linolenic acid) to 20: 4 n-6 (arachidonic acid) and on delta 6 desaturation of 18: 2 n-6 (linoleic acid) to 18:3 n-6 (gamma-linolenic acid) were investigated in two different studies using rat liver homogenates. In the first study, rats were fed a semi-synthetic fat-free diet. When unlabelled 18:3 n-3 was added to the incubation of 14C 18:2 or 14C 20:3, the desaturation rates decreased. delta 6 Desaturation was more strongly inhibited than delta 5 desaturation. The position isomer, gamma-linolenic acid, had no significant effect on delta 6 and delta 5 desaturation. In the second study, the rats were fed a diet including alpha-linolenic acid in the form of rapeseed oil containing no erucic acid. The control animals were fed a peanut oil diet. When alpha-linolenic-fed rats were compared to control animals, we found that delta 6 desaturase activity was lower in the alpha-linolenic-fed animals. In contrast, there was no significant effect on the desaturation rate when 14C 20:3 n-6 was used as a substrate. Our results lead to the conclusion that alpha-linolenic acid, when given to rats as dietary rapeseed oil, partly inhibited delta 6 desaturation in vitro, but did not affect significantly subsequent delta 5 desaturation in the biosynthesis of arachidonic acid. The inhibition of the delta 5 desaturation step, when alpha-linolenic acid was added to the incubation, might be due to an unknown competitive mechanism. These observations have been discussed in relation with the current literature.
在两项不同的研究中，使用大鼠肝脏匀浆研究了α-亚麻酸对20:3 n-6（二高-γ-亚麻酸）向20:4 n-6（花生四烯酸）的Δ5去饱和作用以及对18:2 n-6（亚油酸）向18:3 n-6（γ-亚麻酸）的Δ6去饱和作用的影响。在第一项研究中，给大鼠喂食半合成无脂饮食。当将未标记的18:3 n-3添加到14C 18:2或14C 20:3的孵育体系中时，去饱和率降低。Δ6去饱和作用比Δ5去饱和作用受到的抑制更强。位置异构体γ-亚麻酸对Δ6和Δ5去饱和作用无显著影响。在第二项研究中，给大鼠喂食含有不含芥酸的菜籽油形式的α-亚麻酸的饮食。对照动物喂食花生油饮食。当将喂食α-亚麻酸的大鼠与对照动物进行比较时，我们发现喂食α-亚麻酸的动物中Δ6去饱和酶活性较低。相比之下，当使用14C 20:3 n-6作为底物时，对去饱和率没有显著影响。我们的结果得出结论，当以菜籽油形式给予大鼠时，α-亚麻酸在体外部分抑制了Δ6去饱和作用，但对花生四烯酸生物合成中随后的Δ5去饱和作用没有显著影响。当将α-亚麻酸添加到孵育体系中时，对Δ5去饱和步骤的抑制可能是由于一种未知的竞争机制。已结合当前文献对这些观察结果进行了讨论。
