title: Free fatty acids decrease circulating ghrelin concentrations in humans.
abstract: OBJECTIVE
  Concentrations of the orexigenic peptide ghrelin is affected by a number of hormones, which also affect circulating levels of free fatty acids (FFAs). The present study was therefore designed to determine the direct effect of FFAs on circulating ghrelin.
  
  
  METHODS
  Eight lean, healthy men were examined for 8 h on four occasions using variable infusion rates (0, 3, 6 and 12 microl/kg per min) of intralipid to create different plasma FFA concentrations. Constant levels of insulin and GH were obtained by administration of acipimox (250 mg) and somatostatin (300 microg/h). At the end of each study day a hyperinsulinaemic-euglycaemic clamp was performed.
  
  
  RESULTS
  Four distinct levels of FFAs were obtained at the end of the lipid infusion period (FFA(LIPID): 0.03 +/- 0.00 vs: 0.49 +/- 0.04, 0.92 +/- 0.08 and 2.09 +/- 0.38 mmol/l; ANOVA P < 0.0001) and during hyperinsulinaemia (FFA(LIPID+INSULIN): 0.02 +/- 0.00 vs: 0.34 +/- 0.03, 0.68 +/- 0.09 and 1.78 +/- 0.32 mmol/l; ANOVA P < 0.0001). Whereas, somatostatin infusion alone reduced ghrelin concentration by approximately 67%, concomitant administration of increasing amounts of intralipid reduced circulating ghrelin by a further 14, 19 and 19% respectively (change in ghrelin: 0.52 +/- 0.05 vs: 0.62 +/- 0.06, 0.72 +/- 0.09 and 0.71 +/- 0.05 microg/l; ANOVA P = 0.04). No further reduction in ghrelin concentration was observed during hyperinsulinaemia.
  
  
  CONCLUSIONS
  FFA exposure between 0 and 1 mmol/l significantly suppresses ghrelin levels independent of ambient GH and insulin levels.
authors.affiliation: Department M (endocrinology and diabetes), Aarhus University Hospital, DK-8000 Aarhus C, Denmark. lars.christian.gormsen@ki.au.dk
authors.forename: Lars C
authors.initials: LC
authors.lastname: Gormsen
authors.forename: Jakob
authors.initials: J
authors.lastname: Gjedsted
authors.forename: Signe
authors.initials: S
authors.lastname: Gjedde
authors.forename: Esben Thyssen
authors.initials: ET
authors.lastname: Vestergaard
authors.forename: Jens S
authors.initials: JS
authors.lastname: Christiansen
authors.forename: Jens Otto
authors.initials: JO
authors.lastname: Jørgensen
authors.forename: Søren
authors.initials: S
authors.lastname: Nielsen
authors.forename: Niels
authors.initials: N
authors.lastname: Møller
mesh_terms: D000328:Adult; D000925:Anticoagulants / Q000008:administration & dosage; D001786:Blood Glucose; D002096:C-Peptide / Q000097:blood; D005217:Fat Emulsions, Intravenous / Q000008:administration & dosage / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000008:administration & dosage* / Q000097:blood*; D054439:Ghrelin; D015309:Glucose Clamp Technique; D006493:Heparin / Q000008:administration & dosage; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D006946:Hyperinsulinism / Q000097:blood; D000960:Hypolipidemic Agents / Q000008:administration & dosage; D007328:Insulin / Q000097:blood; D008297:Male; D036361:Peptide Hormones / Q000097:blood*; D011719:Pyrazines / Q000008:administration & dosage; D013004:Somatostatin / Q000008:administration & dosage
chemical_list: D000925:Anticoagulants; D001786:Blood Glucose; D002096:C-Peptide; D005217:Fat Emulsions, Intravenous; D005230:Fatty Acids, Nonesterified; D054439:Ghrelin; D000960:Hypolipidemic Agents; D007328:Insulin; D036361:Peptide Hormones; D011719:Pyrazines; D019382:Human Growth Hormone; D013004:Somatostatin; D006493:Heparin; C027696:acipimox; D006854:Hydrocortisone