van Winkle L J, Doman D R, Campione A L
J Nutr Sci Vitaminol (Tokyo). 1983 Dec;29(6):701-7. doi: 10.3177/jnsv.29.701.
Tryptophan (Trp) is usually catabolized to CO2, H2O and urea in mammals. Quantitatively, minor branches from this pathway lead to the production of picolinate (PA) and NAD+. Although niacin is a required nutrient when NAD+ synthesis from Trp is insufficient, it is not known if dietary PA is beneficial in such conditions. Two kinds of experiment were used to investigate the effects of dietary PA. First, mice were fed on a diet deficient in Trp for six weeks to diminish endogenous PA synthesis and stores. After this time the body mass of the mice was reduced by approximately 30%. Tryptophan-deficient mice subsequently fed a nutritionally complete diet gained weight more rapidly during the first but not subsequent week(s) of recovery when PA was added to their food. Second, mice were fed on a diet deficient in Trp, niacin and vitamin B-6 during the preimplantation period of pregnancy in an attempt to acutely lower PA synthesis and perhaps alter the embryos thus produced. The rate at which preimplantation blastocysts formed trophoblastic outgrowths when cultured in vitro was stimulated by dietary PA only if these blastocysts came from mice fed on a nutritionally deficient diet. The results suggest that PA serves as a beneficial nutrient under some conditions where its endogenous synthesis may be diminished.
在哺乳动物中，色氨酸（Trp）通常会分解代谢为二氧化碳、水和尿素。从数量上看，该代谢途径的一些小分支会产生吡啶甲酸（PA）和烟酰胺腺嘌呤二核苷酸（NAD⁺）。虽然当色氨酸合成烟酰胺腺嘌呤二核苷酸不足时，烟酸是必需营养素，但尚不清楚在这种情况下，膳食中的吡啶甲酸是否有益。我们通过两种实验来研究膳食吡啶甲酸的作用。首先，给小鼠喂食色氨酸缺乏的饮食六周，以减少内源性吡啶甲酸的合成和储存。六周后，小鼠体重下降了约30%。随后，给色氨酸缺乏的小鼠喂食营养完全的饮食，在恢复的第一周（而非随后几周），当食物中添加吡啶甲酸时，小鼠体重增加更快。其次，在怀孕的植入前期，给小鼠喂食色氨酸、烟酸和维生素B-6缺乏的饮食，试图急性降低吡啶甲酸的合成，并可能改变由此产生的胚胎。只有当这些囊胚来自喂食营养缺乏饮食的小鼠时，体外培养时植入前囊胚形成滋养层细胞生长的速率才会受到膳食吡啶甲酸的刺激。结果表明，在一些内源性吡啶甲酸合成可能减少的情况下，吡啶甲酸可作为一种有益营养素。
