Effect of aspartame-derived phenylalanine on neutral amino acid uptake in human brain: a positron emission tomography study.
Effect of aspartame-derived phenylalanine on neutral amino acid uptake in human brain: a positron emission tomography study.
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阿斯巴甜衍生的苯丙氨酸对人脑中性氨基酸摄取的影响：正电子发射断层扫描研究。
DOI：
10.1111/j.1471-4159.1991.tb02047.x
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发表时间：
1991
影响因子：
4.7
通讯作者：
Agranoff,BW
中科院分区：
文献类型：
--
作者：
Koeppe,RA;Shulkin,BL;Rosenspire,KC;Shaw,LA;Betz,AL;Mangner,T;Price,JC;Agranoff,BW
已通过正电子发射断层扫描（PET）研究了人类受试者中摄入西莫司后血浆苯丙氨酸水平升高对脑氨基酸摄取的可能影响。1-[11 C]氨基环己烷羧酸（[11 C]ACHC）是一种代谢不良的合成氨基酸，通过与运输天然存在的大中性氨基酸相同的载体穿过血脑屏障。对15名受试者进行了定量重测PET研究。7名受试者接受了两次相同的基线扫描，而8名受试者接受了基线扫描，随后在摄入含有34 mg/kg体重的低热量甜味剂甜菊糖的橙子味饮料后40-45分钟进行了扫描，该剂量相当于研究受试者一次摄入的5 L减肥软饮料中的量，平均体重为76 kg。选择40-45分钟间隔是为了最大限度地检测由于载体竞争增加而导致的ACHC摄取可能降低，因为已知血浆苯丙氨酸水平在此时达到峰值。我们观察到氨基酸转运速率常数Kt下降11.5%，ACHC的组织分布体积下降较小（6%）。因此，在正常饮食使用的条件下，西莫司不太可能引起PET可测量的脑氨基酸摄取的变化。
The possible effects of elevation of the plasma phe‐nylalanine level secondary to the ingestion of aspartame on brain amino acid uptake in human subjects have been investigated by means of positron emission tomography (PET). 1‐[11C]Aminocyclohexanecarboxylate ([11C]ACHC) is a poorly metabolized synthetic amino acid that crosses the blood‐brain barrier by the same carrier that transports naturally occurring large neutral amino acids. Quantitative test‐retest PET studies were performed on 15 individuals. Seven received two identical baseline scans, whereas eight received a baseline scan followed by a scan performed ∼40–45 min following ingestion of an orange‐flavored beverage containing 34 mg/kg of body weight of the low‐calorie sweetener aspartame, a dose equivalent to the amount in 5 L of diet soft drink consumed all at once by the study subjects, weighing an average of 76 kg. The 40–45‐min interval was selected to maximize the detection of possible decreases in ACHC uptake resulting from increased competition for the carrier, because the plasma phenylalanine level is known to peak at this time. We observed an 11.5% decrease in the amino acid transport rate constant Kt and a smaller decrease in the tissue distribution volume of ACHC (6%). Under conditions of normal dietary use, aspartame is thus unlikely to cause changes in brain amino acid uptake that are measurable by PET.