Kanazawa A, Fujimoto K
Department of Applied Biochemistry, Faculty of Agriculture, Tohoku University, Sendai, Japan.
J Nutr Sci Vitaminol (Tokyo). 1993 Jun;39(3):253-62. doi: 10.3177/jnsv.39.253.
Effects of endogenous and exogenous polyunsaturated fatty acids (PUFA) on microsomal synthesis of docosahexaenoic acid (DHA) from eicosapentaenoic acid (EPA) in vitro were studied using rat livers. Liver microsomes prepared from three groups of rats which had been fed n-3/n-6 ratios of 0.01, 0.39, and 2.70, respectively, for 1 month, were incubated with [1-14C]EPA at 37 degrees C for 30 min. There were no significant differences between the formations of docosapentaenoic acid (DPA) or DHA in the groups. Liver microsomes from rats fed a diet with an n-3/n-6 ratio of 2.70 for 3 weeks were then incubated with [1-14C]EPA in the presence of unlabeled DHA or arachidonic acid (AA). The additional DHA did not have any effect. However, a significant inhibition of DHA synthesis was observed by addition of AA (EPA/AA = 5:2). These results suggest that the microsomal biosynthesis of DHA in rat liver is not susceptible to feedback inhibition.
使用大鼠肝脏研究了内源性和外源性多不饱和脂肪酸（PUFA）对体外微粒体从二十碳五烯酸（EPA）合成二十二碳六烯酸（DHA）的影响。从分别喂食n-3/n-6比例为0.01、0.39和2.70的三组大鼠制备肝脏微粒体，将其与[1-14C]EPA在37℃孵育30分钟。各组中二十二碳五烯酸（DPA）或DHA的形成之间没有显著差异。然后将喂食n-3/n-6比例为2.70的饮食3周的大鼠的肝脏微粒体与[1-14C]EPA在未标记的DHA或花生四烯酸（AA）存在下孵育。额外的DHA没有任何作用。然而，通过添加AA（EPA/AA = 5:2）观察到DHA合成受到显著抑制。这些结果表明，大鼠肝脏中DHA的微粒体生物合成不易受到反馈抑制。
