title: Gut protein uptake and mechanisms of meal-induced cortisol release.
abstract: The enhanced cortisol release after protein-rich meals might represent a neuroendocrine response to food allergens. We tested whether the antigenicity of proteins contributes to this effect. Twelve healthy men nasogastrically received casein, its less allergenic hydrolysate, and placebo. Contrary to expectations, secretion of cortisol (area under the curve, 742.70 +/- 73.48 vs. 542.95 +/- 70.31 micromol/liter.min, P < 0.03) and ACTH (2020.21 +/- 251.10 vs. 1649.82 +/- 241.23 micromol/liter.min, P < 0.05) was stronger on casein-hydrolysate than casein. Systemic immune activity remained unaffected as indicated by unchanged IL-6 plasma concentrations. This finding indicates that the grade of hydrolysis of a protein and the presence of particular amino acids, rather than its antigenicity, are crucial for the pituitary-adrenal response to nutrients. To further examine whether this response is triggered at the gastrointestinal mucosa or after the substance has reached the circulation, in a supplementary experiment, amino acids were given either nasogastrically or iv to healthy men (n = 4). Only the nasogastric infusion of amino acids induced a significant rise in cortisol concentrations. Serum concentrations of tryptophan, which is known to directly excite the hypothalamo-pituitary-adrenal axis, were comparable for both conditions. We conclude that the meal-related hypothalamo-pituitary-adrenal axis response to amino acids results from a signal that rather acts at the gastrointestinal mucosa than directly via the circulating blood.
authors.affiliation: Department of Neuroendocrinology, University of Lübeck, Ratzeburger Allee 160, Haus 23a, 23538 Lübeck, Germany. benedict@kfg.uni-luebeck.de
authors.forename: Christian
authors.initials: C
authors.lastname: Benedict
authors.forename: Manfred
authors.initials: M
authors.lastname: Hallschmid
authors.forename: Jürgen
authors.initials: J
authors.lastname: Scheibner
authors.forename: Daniel
authors.initials: D
authors.lastname: Niemeyer
authors.forename: Bernd
authors.initials: B
authors.lastname: Schultes
authors.forename: Volker
authors.initials: V
authors.lastname: Merl
authors.forename: Horst L
authors.initials: HL
authors.lastname: Fehm
authors.forename: Jan
authors.initials: J
authors.lastname: Born
authors.forename: Werner
authors.initials: W
authors.lastname: Kern
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D002364:Caseins / Q000493:pharmacokinetics; D004044:Dietary Proteins / Q000493:pharmacokinetics*; D004435:Eating / Q000502:physiology*; D005512:Food Hypersensitivity / Q000503:physiopathology; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D015850:Interleukin-6 / Q000097:blood; D007408:Intestinal Absorption / Q000502:physiology*; D007413:Intestinal Mucosa / Q000502:physiology; D007441:Intubation, Gastrointestinal; D008297:Male
chemical_list: D002364:Caseins; D004044:Dietary Proteins; D015850:Interleukin-6; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone