title: Effect of L-Tryptophan and L-Leucine on Gut Hormone Secretion, Appetite Feelings and Gastric Emptying Rates in Lean and Non-Diabetic Obese Participants: A Randomized, Double-Blind, Parallel-Group Trial.
abstract: OBJECTIVE
  Gut hormones such as cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1) play a role as satiation factors. Strategies to enhance satiation peptide secretion could provide a therapeutic approach for obesity. Carbohydrates and lipids have been extensively investigated in relation to peptide release. In contrast, the role of proteins or amino acids is less clear. Our aim was to compare the effects of the amino acids L-tryptophan (L-trp) and L-leucine (L-leu) separately on gastric emptying and gut peptide secretion.
  
  
  METHODS
  The study was conducted as a randomized (balanced), double-blind, parallel-group trial. A total of 10 lean and 10 non-diabetic obese participants were included. Participants received intragastric loads of L-trp (0.52 g and 1.56 g) and L-leu (1.56 g), dissolved in 300 mL tap water; 75 g glucose and 300 mL tap water served as control treatments.
  
  
  RESULTS
  Results of the study are: i) L-trp at the higher dose stimulates CCK release (p = 0.0018), and induces a significant retardation in gastric emptying (p = 0.0033); ii) L-trp at the higher dose induced a small increase in GLP-1 secretion (p = 0.0257); iii) neither of the amino acids modulated subjective appetite feelings; and iv) the two amino acids did not alter insulin or glucose concentrations.
  
  
  CONCLUSIONS
  L-trp is a luminal regulator of CCK release with effects on gastric emptying, an effect that could be mediated by CCK. L-trp's effect on GLP-1 secretion is only minor. At the doses given, the two amino acids did not affect subjective appetite feelings.
  
  
  BACKGROUND
  ClinicalTrials.gov NCT02563847.
authors.affiliation: Department of Biomedicine, University Hospital Basel, Basel, Switzerland.|Department of Research, St. Claraspital, Basel, Switzerland.
authors.forename: Anne Christin
authors.initials: AC
authors.lastname: Meyer-Gerspach
authors.affiliation: Department of Biomedicine, University Hospital Basel, Basel, Switzerland.
authors.forename: Simon
authors.initials: S
authors.lastname: Häfliger
authors.affiliation: Department of Biomedicine, University Hospital Basel, Basel, Switzerland.
authors.forename: Julian
authors.initials: J
authors.lastname: Meili
authors.affiliation: Diabetes Complications Research Centre, Conway Institute, School of Medicine, University College Dublin, Dublin, Ireland.
authors.forename: Alison
authors.initials: A
authors.lastname: Doody
authors.affiliation: Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Jens F
authors.initials: JF
authors.lastname: Rehfeld
authors.affiliation: Department of Clinical Pharmacology, University Hospital Basel, Basel, Switzerland.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Drewe
authors.affiliation: Department of Biomedicine, University Hospital Basel, Basel, Switzerland.|Department of Research, St. Claraspital, Basel, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Beglinger
authors.affiliation: Department of Biomedicine, University Hospital Basel, Basel, Switzerland.|Department of Research, St. Claraspital, Basel, Switzerland.
authors.forename: Bettina
authors.initials: B
authors.lastname: Wölnerhanssen
mesh_terms: D000328:Adult; D001066:Appetite / Q000187:drug effects*; D002766:Cholecystokinin / Q000378:metabolism*; D004311:Double-Blind Method; D005260:Female; D005746:Gastric Emptying / Q000187:drug effects*; D052216:Glucagon-Like Peptide 1 / Q000378:metabolism*; D006801:Humans; D007930:Leucine / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000378:metabolism*; D014364:Tryptophan / Q000008:administration & dosage*
chemical_list: D052216:Glucagon-Like Peptide 1; D014364:Tryptophan; D002766:Cholecystokinin; D007930:Leucine