F. Verrey: Institute of Physiology, University of Zürich, Winterthurerstr. 190, CH-8057 Zürich, Switzerland.
J Physiol. 2013 Nov 15;591(22):5611-21. doi: 10.1113/jphysiol.2013.258947. Epub 2013 Jul 29.
To maintain nutrient homeostasis the central nervous system integrates signals that promote or inhibit eating. The supply of vital amino acids is tuned by adjusting food intake according to its dietary protein content. We hypothesized that this effect is based on the sensing of individual amino acids as a signal to control food intake. Here, we show that food intake was most potently reduced by oral L-arginine (Arg), L-lysine (Lys) and L-glutamic acid (Glu) compared to all other 17 proteogenic amino acids in rats. These three amino acids induced neuronal activity in the area postrema and the nucleus of the solitary tract. Surgical lesion of the area postrema abolished the anorectic response to Arg and Glu, whereas vagal afferent lesion prevented the response to Lys. These three amino acids also provoked gastric distension by differentially altering gastric secretion and/or emptying. Importantly, these peripheral mechanical vagal stimuli were dissociated from the amino acids' effect on food intake. Thus, Arg, Lys and Glu had a selective impact on food processing and intake suggesting them as direct sensory input to assess dietary protein content and quality in vivo. Overall, this study reveals novel amino acid-specific mechanisms for the control of food intake and of gastrointestinal function.
为了维持营养稳态，中枢神经系统整合了促进或抑制进食的信号。根据饮食蛋白质含量调整食物摄入量，从而调节重要氨基酸的供应。我们假设这种效应是基于对单个氨基酸作为控制食物摄入的信号的感知。在这里，我们发现在大鼠中，与其他 17 种蛋白质氨基酸相比，口服 L-精氨酸（Arg）、L-赖氨酸（Lys）和 L-谷氨酸（Glu）最能减少食物摄入。这三种氨基酸诱导后肠和孤束核中的神经元活性。后肠切除术消除了 Arg 和 Glu 的厌食反应，而迷走神经传入神经损伤则阻止了 Lys 的反应。这三种氨基酸还通过改变胃分泌和/或排空来引起胃扩张。重要的是，这些外周机械性迷走神经刺激与氨基酸对食物摄入的影响是分离的。因此，Arg、Lys 和 Glu 对食物处理和摄入有选择性影响，表明它们是评估体内膳食蛋白质含量和质量的直接感觉输入。总的来说，这项研究揭示了控制食物摄入和胃肠道功能的新的氨基酸特异性机制。
