Penz A M, Clifford A J, Rogers Q R, Kratzer F H
J Nutr. 1984 Jan;114(1):33-41. doi: 10.1093/jn/114.1.33.
Three experiments were conducted with young chicks to determine whether dietary leucine affects the conversion of tryptophan to niacin. Either tryptophan or niacin improved growth and reduced perosis when chicks were fed a purified diet marginal in tryptophan and deficient in niacin. Addition of 4.8% L-leucine to the diet did not alter the growth and perosis prevention response obtained with tryptophan. Liver weight was slightly increased by the addition of 5.4% L-leucine to the diet. Plasma insulin was slightly reduced by leucine and by isoleucine and valine. Picolinic carboxylase in the kidney was reduced in chicks fed 0.2% tryptophan with no niacin and was also reduced when isoleucine and valine were added to the diets. Liver picolinic carboxylase activity was not influenced by diet. Plasma isoleucine and valine were reduced by the addition of leucine to the diet and were increased again when isoleucine and valine were added to the diet. Plasma leucine was increased by the addition of leucine but was not altered by valine and isoleucine. Plasma tryptophan was not influenced by dietary supplements of leucine or isoleucine and valine. The results show that in the chick there is no evidence for an effect of leucine on the tryptophan to niacin pathway.
用幼雏进行了三项实验，以确定日粮中的亮氨酸是否会影响色氨酸向烟酸的转化。当雏鸡饲喂色氨酸含量处于临界水平且缺乏烟酸的纯化日粮时，色氨酸或烟酸均可促进生长并减少滑腱症。在日粮中添加4.8%的L-亮氨酸并不会改变色氨酸所产生的促进生长和预防滑腱症的效果。在日粮中添加5.4%的L-亮氨酸会使肝脏重量略有增加。亮氨酸、异亮氨酸和缬氨酸均可使血浆胰岛素水平略有降低。饲喂不含烟酸的0.2%色氨酸日粮的雏鸡，其肾脏中的吡啶甲酸羧化酶水平降低，在日粮中添加异亮氨酸和缬氨酸时该酶水平也会降低。日粮对肝脏吡啶甲酸羧化酶活性没有影响。在日粮中添加亮氨酸会使血浆异亮氨酸和缬氨酸水平降低，而添加异亮氨酸和缬氨酸后其水平会再次升高。添加亮氨酸会使血浆亮氨酸水平升高，但缬氨酸和异亮氨酸不会对其产生影响。日粮中添加亮氨酸、异亮氨酸和缬氨酸不会影响血浆色氨酸水平。结果表明，在雏鸡中，没有证据表明亮氨酸会对色氨酸向烟酸的转化途径产生影响。
