title: Metabolic and endocrine effects of physiological increments in plasma ghrelin concentrations.
abstract: BACKGROUND
  Growing evidence indicates that the administration of large amounts of ghrelin to humans increases circulating concentrations of several pituitary and adrenal hormones, induces hyperglycemia and reduces serum insulin concentrations. At present, it is not known whether physiological increments in plasma ghrelin concentrations affect glucose kinetics or hormone concentrations in humans.
  
  
  RESULTS
  We compared the effects of two- and three-fold increments in plasma ghrelin concentrations in eight healthy subjects during a 2 h intravenous infusion of 7.5 (GHRE7.5), 15 (GHRE15) pmol kg(-1) min(-1) acylated human ghrelin or placebo (PL), in a randomized double-blind study. Compared with PL (146 +/- 24 pM) plasma ghrelin concentrations increased at 120 min (p<0.001) about two-fold after GHRE7.5 (300 +/- 35 pM) and three-fold after GHRE15 (494 +/- 30 pM). GHRE15 significantly increased circulating concentrations of NEFA, GH, ACTH, epinephrine, and prolactin (p<0.01). GHRELIN7.5 significantly (p<0.01) increased only serum GH concentrations. Neither ghrelin infusions changed glucose flux or circulating concentrations of glucose, insulin, C-peptide, glucagon, IGF-1, cortisol and norepinephrine.
  
  
  CONCLUSIONS
  GH secretion is the only response that is stimulated by physiological increments in plasma ghrelin concentrations; about three-fold increases in plasma ghrelin concentrations are required to elicit the responses of epinephrine, prolactin, ACTH and NEFA.
authors.affiliation: Department of Internal Medicine, Section of Internal Medicine and Endocrine and Metabolic Sciences (I.M.I.S.E.M.), University of Perugia, Via Enrico Dal Pozzo, 06126 Perugia, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Lucidi
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Murdolo
authors.forename: Chiara
authors.initials: C
authors.lastname: Di Loreto
authors.forename: Natascia
authors.initials: N
authors.lastname: Parlanti
authors.forename: Arianna
authors.initials: A
authors.lastname: De Cicco
authors.forename: Cristina
authors.initials: C
authors.lastname: Fatone
authors.forename: Chiara
authors.initials: C
authors.lastname: Taglioni
authors.forename: Carmine
authors.initials: C
authors.lastname: Fanelli
authors.forename: Fabio
authors.initials: F
authors.lastname: Broglio
authors.forename: Ezio
authors.initials: E
authors.lastname: Ghigo
authors.forename: Geremia B
authors.initials: GB
authors.lastname: Bolli
authors.forename: Fausto
authors.initials: F
authors.lastname: Santeusanio
authors.forename: Pierpaolo
authors.initials: P
authors.lastname: De Feo
mesh_terms: D000215:Acylation; D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004703:Endocrine System / Q000187:drug effects*; D004837:Epinephrine / Q000097:blood; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D054439:Ghrelin; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D007262:Infusions, Intravenous; D007328:Insulin / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D036361:Peptide Hormones / Q000008:administration & dosage* / Q000097:blood* / Q000502:physiology; D011388:Prolactin / Q000097:blood
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D054439:Ghrelin; D007328:Insulin; D036361:Peptide Hormones; D000324:Adrenocorticotropic Hormone; D011388:Prolactin; D013006:Growth Hormone; D004837:Epinephrine