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Abstract：
Breast milk is the only source of the essential amino acid tryptophan (TRP) in breast-fed infants. Low levels of TRP could have implications for infant neurodevelopment. The objectives of the present study were to compare the relationship of TRP and its neuroactive pathway metabolites kynurenine (Kyn) and kynurenic acid (KynA) in preterm and term expressed breast milk (EBM) in the first 14 d following birth, and the relationship of TRP metabolism to maternal stress and immune status. A total of twenty-four mothers were recruited from Cork University Maternity Hospital: twelve term (>38 weeks) and twelve preterm (<35 weeks). EBM samples were collected on days 7 and 14. Free TRP, Kyn and KynA were measured using HPLC, total TRP using MS, cytokines using the Meso Scale Discovery (MSD) assay system, and cortisol using a cortisol ELISA kit. Although total TRP was higher in preterm EBM in comparison with term EBM (P < 0·05), free TRP levels were lower (P < 0·05). Kyn, KynA and the Kyn:TRP ratio increased significantly in term EBM from day 7 to day 14 (P < 0·05), but not in preterm EBM. TNF-α, IL-6 and IL-8 were higher in day 7 preterm and term EBM in comparison with day 14. There were no significant differences between term and preterm EBM cortisol levels. Increased availability of total TRP, lower levels of free TRP and alterations in the temporal dynamics of TRP metabolism in preterm compared with term EBM, coupled with higher EBM inflammatory markers on day 7, may have implications for the neurological development of exclusively breast-fed preterm infants.
摘要：
母乳是母乳喂养婴儿中必需氨基酸色氨酸（TRP）的唯一来源。低水平的TRP可能对婴儿神经发育有影响。本研究的目的是比较TRP及其神经活性途径代谢物犬尿氨酸（Kyn）和犬尿氨酸（KynA）在早产和足月表达的母乳（EBM）中的关系。以及TRP代谢与母体应激和免疫状态的关系。从科克大学妇产医院招募了总共24名母亲：12个月（>38周）和12个早产（<35周）。在第7天和第14天收集EBM样品。免费TRP,Kyn和Kyna使用HPLC测量，使用MS的总TRP，使用中观尺度发现(MSD)测定系统的细胞因子，和皮质醇使用皮质醇ELISA试剂盒。尽管早产EBM的总TRP高于足月EBM（P<0·05），游离TRP水平较低(P<0·05)。Kyn,从第7天到第14天，足月EBM的KynA和Kyn：TRP比率显着增加（P<0·05），但不是早产EBM。TNF-α,与第14天相比，第7天早产和足月EBM的IL-6和IL-8更高。足月和早产EBM皮质醇水平之间没有显着差异。增加总TRP的可用性，与足月EBM相比，早产儿的游离TRP水平较低，TRP代谢的时间动力学改变，再加上第7天较高的EBM炎症标志物,可能对纯母乳喂养早产儿的神经系统发育有影响.
