title: GH response to hypoglycemia and clonidine in the GH-releasing hormone resistance syndrome.
abstract: GH secretion by the pituitary is the result of the balance between the stimulatory effect of GHRH and the inhibitory effect of SS. Patients with mutations in GHRH receptor (GHRH-R) gene (GHRH-R) offer a unique model to study the mechanism of action of different GH secretion stimuli. In the past, we have demonstrated a small but significant GH response to a GH secretagogue (GHRP-2) in a homogenous cohort of patients with severe GH deficiency (GHD) due to a homozygous null mutation in GHRH-R (IVS1+1G-->A). Now, we sought to determine if we could detect a GH response to hypoglycemia (ITT: insulin tolerance test) or clonidine (CL) in these patients. Nine young GHD subjects underwent both ITT and CL tests, and 2 additional subjects underwent only CL test. There was a small but significant GH increase during ITT, but not during CL test. These results indicate that a minimal albeit significant GH response to ITT can occur despite complete lack of GHRH-R function.
authors.affiliation: Division of Endocrinology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA. salvator@jhmi.edu
authors.forename: R
authors.initials: R
authors.lastname: Salvatori
authors.forename: M G
authors.initials: MG
authors.lastname: Serpa
authors.forename: G
authors.initials: G
authors.lastname: Parmigiani
authors.forename: A V O
authors.initials: AV
authors.lastname: Britto
authors.forename: J L M
authors.initials: JL
authors.lastname: Oliveira
authors.forename: C R P
authors.initials: CR
authors.lastname: Oliveira
authors.forename: C M
authors.initials: CM
authors.lastname: Prado
authors.forename: C T
authors.initials: CT
authors.lastname: Farias
authors.forename: J C
authors.initials: JC
authors.lastname: Almeida
authors.forename: T A R
authors.initials: TA
authors.lastname: Vicente
authors.forename: M H
authors.initials: MH
authors.lastname: Aguiar-Oliveira
mesh_terms: D000293:Adolescent; D000328:Adult; D001786:Blood Glucose / Q000187:drug effects; D001827:Body Height; D002648:Child; D002675:Child, Preschool; D003000:Clonidine / Q000494:pharmacology*; D004393:Dwarfism, Pituitary / Q000097:blood* / Q000235:genetics; D005260:Female; D013007:Growth Hormone-Releasing Hormone / Q000235:genetics; D019382:Human Growth Hormone / Q000097:blood / Q000378:metabolism*; D006801:Humans; D007003:Hypoglycemia / Q000139:chemically induced / Q000378:metabolism*; D007328:Insulin / Q000009:adverse effects; D008297:Male; D013577:Syndrome; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D007328:Insulin; D019382:Human Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D003000:Clonidine