Amino acid homeostasis in mice lacking the peptide transporter PEPT1
Final Report Abstract
Mice lacking PEPT1 did not display altered development, body weight or fertility and this can not be explained by compensatory changes in gene expression and/or functions of intestinal transporters for free amino acids. With regard to the contribution of PEPT1 to overall amino acid absorption in intestine, we could demonstrate that PEPT1 seems important only after high dietary protein intake when amino acid transport processes are saturated and PEPT1 can provide additional absorption capacity. Since renal amino acid excretion remained crossly also unchanged (except for proline), elevated basal concentrations of plasma amino acids in PEPT1-deficient animals seem to arise mainly from yet unexplained alterations in hepatic and renal amino acid metabolism. On a high-protein diet, mice lacking PEPT1 display a strong phenotype with most prominent reductions in food intake, reduced body weight and a lack of weight gain despite a regain of food intake after some 5 days. Plasma amino acid concentrations were altered as well, especially those of BCAAs. This unexpected finding however suggests that PEPT1 may contribute to satiety control in a yet unexplained manner.
Publications
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Gene ablation for PEPT1 in mice abolishes the effects of dipeptides on small intestinal fluid absorption, short-circuit current, and intracellular pH. Am J Physiol Gastrointest Liver Physiol. 2010 Jul;299:G265-74
Chen M, Singh A, Xiao F, Dringenberg U, Wang J, Engelhardt R, Yeruva S, Rubio- Aliaga I, Nässl AM, Kottra G, Daniel H, Seidler U
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Amino acid absorption and homeostasis in mice lacking the intestinal peptide transporter PEPT1. Am J Physiol Gastrointest Liver Physiol. 2011 Feb 24. [Epub ahead of print]
Nässl AM, Rubio-Aliaga I, Fenselau H, Marth M, Kottra G, Daniel H
