Bordoni A, Hrelia S, Lorenzini A, Bergami R, Cabrini L, Biagi P L, Tolomelli B
Dipartimento di Biochimica G. Moruzzi, Bologna, Italy.
Prostaglandins Leukot Essent Fatty Acids. 1998 Jun;58(6):417-20. doi: 10.1016/s0952-3278(98)90163-6.
Delta-6-desaturase (D6D) activity is influenced by many nutritional and non-nutritional factors, among which one of the most important is aging. D6D activity could be susceptible to the dual influence of aging itself and of nutritional deficiencies, due to the reduced intake and/or absorption of essential nutrients. Particularly, vitamin B6 deficiency might be a crucial factor for D6D activity in aged people. Using 20 month old Sprague-Dawley rats fed a diet with a subnormal level of vitamin B6, we evaluated D6D activity for linoleic acid (LA) and alpha-linolenic acid (ALA) in liver microsomes, and the fatty acid composition of microsomal total lipids. We observed a diminished D6D activity for LA and also for ALA in vitamin B6-deficient animals, being approximately 63% and 81% respectively of the corresponding activity in control rats. As a consequence, significant modifications in the relative molar content of microsomal fatty acids were observed. The content of arachidonic and docosahexaenoic acid, the main products of the conversion of LA and ALA respectively, decreased, LA content increased and a decrease in the unsaturation index was observed in liver microsomes of B6-deficient rats. The foregoing results suggest that the impairment of D6D activity by vitamin B6 deficiency might be an important factor in decreasing the synthesis of n-6 and n-3 PUFAs. This may be particularly important in aging, where D6D activity is already impaired.
Δ-6-去饱和酶（D6D）活性受多种营养和非营养因素影响，其中最重要的因素之一是衰老。由于必需营养素的摄入量和/或吸收减少，D6D活性可能易受衰老本身和营养缺乏的双重影响。特别是，维生素B6缺乏可能是老年人D6D活性的关键因素。我们使用20月龄的Sprague-Dawley大鼠，给它们喂食维生素B6水平低于正常的饮食，评估了肝脏微粒体中D6D对亚油酸（LA）和α-亚麻酸（ALA）的活性，以及微粒体总脂质的脂肪酸组成。我们观察到，在维生素B6缺乏的动物中，D6D对LA和ALA的活性均降低，分别约为对照大鼠相应活性的63%和81%。因此，观察到微粒体脂肪酸的相对摩尔含量有显著变化。在维生素B6缺乏大鼠的肝脏微粒体中，分别作为LA和ALA转化主要产物的花生四烯酸和二十二碳六烯酸含量降低，LA含量增加，不饱和指数下降。上述结果表明，维生素B6缺乏导致的D6D活性受损可能是减少n-6和n-3多不饱和脂肪酸合成的一个重要因素。这在衰老过程中可能尤为重要，因为衰老时D6D活性已经受损。
