title: Alpha-2-adrenergic pathways release growth hormone via a non-GRF-dependent mechanism in normal human subjects.
abstract: Administration of a supramaximal dose of GRF 1-44 (200 micrograms, i.v.) to normal human volunteers increased GH levels while a further bolus of GRF (200 micrograms i.v.) given 2 hours later failed to increase plasma GH levels. In contrast, alpha-adrenergic receptor agonism with either propranolol-adrenaline infusion or clonidine increased plasma GH levels at a time when GH responses to this supramaximal dose of GRF were absent. This indicates that alpha-adrenergic pathways stimulate GH secretion through a non-GRF-dependent mechanism in normal human subjects.
authors.affiliation: 2a Divisione di Medicina Generale, Arcispedale, S. Maria Nuova, Reggio Emilia, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Valcavi
authors.forename: C
authors.initials: C
authors.lastname: Dieguez
authors.forename: M D
authors.initials: MD
authors.lastname: Page
authors.forename: M
authors.initials: M
authors.lastname: Zini
authors.forename: P
authors.initials: P
authors.lastname: Casoli
authors.forename: I
authors.initials: I
authors.lastname: Portioli
authors.forename: M F
authors.initials: MF
authors.lastname: Scanlon
mesh_terms: D000328:Adult; D003000:Clonidine / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D013006:Growth Hormone / Q000097:blood / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D006801:Humans; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D011433:Propranolol / Q000494:pharmacology; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*
chemical_list: D011942:Receptors, Adrenergic, alpha; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D011433:Propranolol; D003000:Clonidine; D004837:Epinephrine