Steinert Robert E, Ullrich Sina S, Geary Nori, Asarian Lori, Bueter Marco, Horowitz Michael, Feinle-Bisset Christine
Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
NHMRC Centre of Research Excellence in Translating Nutritional Science to Good Health University of Adelaide, Adelaide, South Australia, Australia.
Physiol Rep. 2017 Nov;5(21). doi: 10.14814/phy2.13492.
In contrast to the many studies of the effects of individual amino acids (AAs) on eating, no studies have compared the effects of different AAs on eating and underlying preabsorptive gastrointestinal mechanisms. To compare the effects of intraduodenal infusions of l-tryptophan (TRP), l-leucine (LEU), l-phenylalanine (PHE) and l-glutamine (GLN) on appetite, gastrointestinal hormone responses (including ghrelin, cholecystokinin (CCK), peptide YY (PYY) and glucagon-like peptide-1 [GLP-1]), glycemia (glucagon, insulin and glucose) and test meal size in healthy males, we retrospectively analyzed data from four published independent, randomized, double-blind, placebo-controlled studies of 90-min intraduodenal infusions of the individual AAs. The designs of the studies were identical, except the dose of TRP (0.15 kcal/min) was lower than that of the other AAs (0.45 kcal/min) because higher doses of this AA were not well tolerated. TRP and LEU decreased intake more than PHE (reductions relative to control, 219 ± 68, ~170 ± 48 and ~12 ± 57 kcal, respectively), and TRP decreased intake more than GLN (31 ± 82 kcal). These effects of TRP and LEU versus GLN, but not versus PHE, were paralleled by greater decreases in plasma ghrelin, and increases in CCK, concentrations. TRP increased PYY more than GLN or LEU, but not PHE. LEU increased PYY less than PHE. No significant differences were detected for GLP-1. PHE increased glucagon more than TRP or LEU, and increased insulin more than TRP. Under our experimental conditions, intraduodenal TRP and LEU were more satiating than PHE and GLN. The greater satiating efficacy of LEU versus PHE was significantly dissociated from the effects of these AAs on PYY, while the greater satiating potency of TRP versus PHE was significantly dissociated from the effects of these AAs on insulin and glucagon. In contrast, ghrelin and CCK, and potentially other mechanisms, including central sensing of individual AAs, appear to be stronger candidate mechanisms for the relative satiating effects obtained.
与众多关于单个氨基酸（AA）对进食影响的研究不同，尚无研究比较不同氨基酸对进食及潜在的吸收前胃肠道机制的影响。为比较十二指肠内输注l - 色氨酸（TRP）、l - 亮氨酸（LEU）、l - 苯丙氨酸（PHE）和l - 谷氨酰胺（GLN）对健康男性食欲、胃肠激素反应（包括胃饥饿素、胆囊收缩素（CCK）、肽YY（PYY）和胰高血糖素样肽 - 1 [GLP - 1]）、血糖（胰高血糖素、胰岛素和葡萄糖）以及试餐量的影响，我们回顾性分析了四项已发表的独立、随机、双盲、安慰剂对照研究的数据，这些研究为90分钟十二指肠内输注单个氨基酸。研究设计相同，只是TRP的剂量（0.15千卡/分钟）低于其他氨基酸（0.45千卡/分钟），因为该氨基酸的更高剂量耐受性不佳。TRP和LEU比PHE更能减少摄入量（相对于对照的减少量分别约为219±68、170±48和12±57千卡），且TRP比GLN更能减少摄入量（约31±82千卡）。TRP和LEU相对于GLN（而非相对于PHE）的这些作用，伴随着血浆胃饥饿素的更大降低以及CCK浓度的升高。TRP比GLN或LEU更能增加PYY，但对PHE无此作用。LEU增加PYY的程度低于PHE。未检测到GLP - 1有显著差异。PHE比TRP或LEU更能增加胰高血糖素，且比TRP更能增加胰岛素。在我们的实验条件下，十二指肠内输注TRP和LEU比PHE和GLN更具饱腹感。LEU相对于PHE更强的饱腹感功效与这些氨基酸对PYY的作用显著分离，而TRP相对于PHE更强的饱腹感效力与这些氨基酸对胰岛素和胰高血糖素的作用显著分离。相比之下，胃饥饿素和CCK，以及潜在的其他机制，包括对单个氨基酸的中枢感知，似乎是产生相对饱腹感效应的更强候选机制。
