Breuillé Denis, Béchereau Fabienne, Buffière Caroline, Denis Philippe, Pouyet Corinne, Obled Christiane
Centre de Recherches Nestlé, Vers chez-les-blanc, P.O. Box 44 CH1000, Lausanne 26, Switzerland.
Clin Nutr. 2006 Aug;25(4):634-42. doi: 10.1016/j.clnu.2005.11.009. Epub 2006 Jan 4.
Muscle wasting and increased synthesis of proteins and compounds involved in host defense characterize severe injury. The aims of the studies reported were to determine which amino acids exhibited an increased tissue content linked to anabolic processes in infected rats by comparison with healthy pair-fed controls, and to explore whether diets supplemented with these amino acids attenuate the catabolic response to infection.
Total amino acid content of the liver and the rest of the body were measured in control well-fed rats, in infected rats and their pair-fed controls 2 days after infection. In the nutritional protocols, infected rats were fed with a diet supplemented with alanine (basal diet), or threonine, serine, aspartate, asparagine and arginine (AA) or AA+cysteine (complete diet).
Infection significantly increased liver total amino acid content by 38% for most amino acids. In contrast, the percentage increase was cysteine 79.3, threonine 45.3, aspartate-asparagine 46.3 and serine 46.5. Whole body without liver content of most amino acids decreased after infection due to the catabolic response, while the content of cysteine increased by 6% (P<0.05) and those of threonine and arginine did not decrease. After infection, animals fed the complete diet lost less weight than animals fed the basal diet (P<0.05). Furthermore, AA plus cysteine supplementation reduced significantly urinary nitrogen excretion and muscle wasting.
The results provide evidence that diet supplementation with cysteine, threonine, serine, aspartate-asparagine and arginine supports the synthesis of vital proteins to spare body protein catabolism during infection.
肌肉消耗以及参与宿主防御的蛋白质和化合物合成增加是严重损伤的特征。本报告中各项研究的目的是，通过与健康的配对喂养对照组进行比较，确定在受感染大鼠中，哪些氨基酸的组织含量增加与合成代谢过程相关，并探讨补充这些氨基酸的饮食是否能减轻对感染的分解代谢反应。
在感染后2天，测量对照喂养良好的大鼠、受感染大鼠及其配对喂养对照组肝脏和身体其他部位的总氨基酸含量。在营养方案中，受感染大鼠分别喂食补充丙氨酸的饮食（基础饮食）、或苏氨酸、丝氨酸、天冬氨酸、天冬酰胺和精氨酸（氨基酸组）、或氨基酸 + 半胱氨酸（完整饮食）。
感染使大多数氨基酸的肝脏总氨基酸含量显著增加38%。相比之下，增加的百分比分别为：半胱氨酸79.3%、苏氨酸45.3%、天冬氨酸 - 天冬酰胺46.3%、丝氨酸46.5%。由于分解代谢反应，感染后不包括肝脏的身体大部分氨基酸含量下降，而半胱氨酸含量增加6%（P<0.05），苏氨酸和精氨酸含量未下降。感染后，喂食完整饮食的动物比喂食基础饮食的动物体重减轻更少（P<0.05）。此外，补充氨基酸加半胱氨酸可显著减少尿氮排泄和肌肉消耗。
结果表明，补充半胱氨酸、苏氨酸、丝氨酸、天冬氨酸 - 天冬酰胺和精氨酸的饮食有助于在感染期间合成重要蛋白质，从而减少身体蛋白质的分解代谢。
