Specific oral amino acids induce a protective response

Abstract

Food intake is controlled by the central nervous system that uses multiple signals to drive food selection and meal termination. To test the hypothesis that specific amino acids (AAs) may act as satiation signals, all 20 proteogenic AAs were administered separately at isomolar doses by gavage. Only Arg, Lys and Glu reduced 1h food intake in rats by 50%, 47% and 35%, respectively. Arg and Lys evoked neuronal activity visualized by cFOS staining in the area postrema and the nucleus of the solitary tract. In a two‐bottle conditioned taste aversion test Arg and Lys provoked saccharine rejection, suggesting that their administration triggers a protective response. At the level of the intestine, these AAs induced a strong secretion leading to changes in plasma Cl− (−8% for Arg) and albumin (+9% for Arg, +12% for Lys) concentrations. Furthermore, delayed gastric phenol red release (25% Lys) and accelerated transit into the caecum (428% with Arg, 322% with Lys) indicated changes in intestinal motility. Taken together, these results suggest that oral Lys and Arg administration trigger a protective mechanism. By their dilution and retention in the stomach and accelerated transit through the small intestine their efficient acute absorption might be prevented and thereby the milieu interieur protected from an acute overload. This project is supported by Zurich Center for Integrative Human Physiology.