title: Effects of alpha- and beta-adrenergic agonists and antagonists on growth hormone secretion in man.
abstract: The adrenergic system is involved in the neural control of GH secretion with both stimulatory and inhibitory influences mainly mediated via GHRH and/or somatostatin modulation. To throw further light on adrenergic neuroregulation of somatotrophic function in man, the effect of various catecholamine agonists and antagonists on basal or GHRH-stimulated GH secretion was studied. Twenty-one adult males aged 20-30 years underwent the following studies: 1. clonidine (CLON), alpha 2-agonist, (15 micrograms/min infused i.v. from 0 to +10 min) alone and preceded by yohimbine (YOH), alpha 2-antagonist, (30 mg orally at -50 min); 2. GHRH (GHRH 44, 1 microgram/kg i.v. bolus at 0 min) alone and preceded by YOH; 3. CLON alone and combined with methoxamine (METHOX), alpha 1-agonist, (1 mg/min infused i.v. from -10 to +10 min); 4. GHRH alone and combined with i.v. infusion of phentolamine (PHEN), alpha 1/alpha 2-antagonist, (0.5 mg/min from -60 to +30 min); 5. GHRH alone and combined with i.v. infusion of salbutamol (SAL), beta 2-agonist, (10 micrograms/min from -5 to +15 min). The GH response to CLON was inhibited by YOH (area under the response curve, mean +/- S.E.: 672.6 +/- 143.0 vs. 219.6 +/- 16.7 micrograms/l/h, P less than 0.05) but was not modified by METHOX (278.4 +/- 94.1 vs. 216.7 +/- 115.5 micrograms/l/h). On the other hand, YOH was unable to affect the GH response to GHRH (339.3 +/- 19.1 vs. 518 +/- 172.8 micrograms/l/h).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Biomedicine, University of Turin, Hospital Molinette, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Mazza
authors.forename: E
authors.initials: E
authors.lastname: Ghigo
authors.forename: J
authors.initials: J
authors.lastname: Bellone
authors.forename: E
authors.initials: E
authors.lastname: Arvat
authors.forename: E
authors.initials: E
authors.lastname: Revelli
authors.forename: S G
authors.initials: SG
authors.lastname: Cella
authors.forename: F
authors.initials: F
authors.lastname: Brambilla
authors.forename: E E
authors.initials: EE
authors.lastname: Müller
authors.forename: F
authors.initials: F
authors.lastname: Camanni
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000328:Adult; D000420:Albuterol / Q000494:pharmacology; D003000:Clonidine / Q000494:pharmacology; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone; D006801:Humans; D008297:Male; D008729:Methoxamine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D015016:Yohimbine; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D008729:Methoxamine; D003000:Clonidine; D000420:Albuterol; D010646:Phentolamine