title: Four-hour infusion of hydrocortisone does not suppress the nocturnal increase of circulating acyl- or desacyl-ghrelin concentrations in healthy young adults.
abstract: BACKGROUND
  Ghrelin is a 28-amino acid peptide released from the stomach. Ghrelin is found in the circulation in two forms: acyl- and desacyl-ghrelin. Acyl- and desacyl-ghrelin concentrations increase at night, when cortisol concentrations are low. Acute ghrelin administration increases ACTH and cortisol concentrations and a feedback loop between the ghrelin and ACTH-cortisol axis has been postulated. A previous study showed that exogenously induced hypercortisolism for 5 days decreased plasma ghrelin concentrations.
  
  
  OBJECTIVE
  The objective of the study was to determine whether a 4-hour infusion of hydrocortisone given at a time of low endogenous cortisol concentrations (11:00 pm to 3:00 am) acutely suppresses acyl- and desacyl-ghrelin.
  
  
  METHODS
  Eight healthy young men aged (mean ± SD) 21.5 ± 2.7 years with a body mass index of 22.4 ± 2.5 kg/m(2) were studied in a single-blind, placebo-controlled study during two separate overnight admissions on the Clinical Research Unit. The volunteers received either a 4-hour (11:00 pm to 3:00 am) infusion of hydrocortisone or a saline infusion. The hydrocortisone infusion rate was 0.3 mg/kg·h for the initial 3 minutes, 0.24 mg/kg·h for 9 minutes, and then 0.135 mg/kg·h until the end of the infusion. Plasma acyl- and desacyl-ghrelin concentrations (in-house two site sandwich assay) and ACTH, cortisol, insulin, GH, and glucose levels were measured every 10 minutes for 16 hours (5:00 pm to 9:00 am).
  
  
  RESULTS
  The mean differences (lower 95% limit; upper 95% limit) between the saline infusion and hydrocortisone infusion for acyl- and desacyl-ghrelin concentrations were not significantly different from zero. The infusion period (11:00 pm to 3:00 am) was as follows: acyl-ghrelin, 0.22 (-7.39; 7.83) (P = 1.00); desacyl-ghrelin, -3.36 (-17.66; 10.95) (P = 1.00). The postinfusion period (3:00-7:00 am) was as follows: acyl-ghrelin, 8.68 (1.07; 16.28); (P = .056); desacyl-ghrelin, 8.75 (-5.56; 23.05) (P = .403).
  
  
  CONCLUSIONS
  A short-term increase in circulating cortisol concentrations by exogenous hydrocortisone infusion does not suppress circulating nocturnal acyl- or desacyl-ghrelin concentrations. Thus, it is likely that the diurnal pattern of ghrelin secretion is under circadian control and not directly regulated by cortisol.
authors: Division of Endocrinology and Metabolism (R.N., J.L., S.S.P., L.S.F., B.D.G., M.O.T.), Department of Medicine, and Department of Health Sciences (J.P.), and Center for Diabetes Technology (L.S.F.), University of Virginia, Charlottesville, Virginia 22908.
authors: Ralf
authors: R
authors: Nass
authors: Jianhua
authors: J
authors: Liu
authors: James
authors: J
authors: Patrie
authors: Suzan S
authors: SS
authors: Pezzoli
authors: Leon S
authors: LS
authors: Farhy
authors: Bruce D
authors: BD
authors: Gaylinn
authors: Michael O
authors: MO
authors: Thorner
mesh_terms: D000293:Adolescent; D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage; D001786:Blood Glucose / Q000378:metabolism; D002940:Circadian Rhythm / Q000187:drug effects*; D054439:Ghrelin / Q000097:blood*; D064368:Healthy Volunteers; D006801:Humans; D006854:Hydrocortisone / Q000008:administration & dosage* / Q000097:blood; D007262:Infusions, Intravenous; D007328:Insulin / Q000097:blood; D008297:Male; D012965:Sodium Chloride / Q000008:administration & dosage; D055815:Young Adult
chemical_list: D000893:Anti-Inflammatory Agents; D001786:Blood Glucose; D054439:Ghrelin; D007328:Insulin; C422650:ghrelin, des-n-octanoyl; D012965:Sodium Chloride; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone