title: Effect of galanin on growth hormone-releasing hormone-stimulated growth hormone secretion in adult patients with nonendocrine diseases on long-term daily glucocorticoid treatment.
abstract: Glucocorticoids are thought to inhibit growth hormone (GH) secretion through an enhancement of endogenous somatostatin tone. The aim of our study was to evaluate the effect of galanin, a neuropeptide that stimulates GH secretion, on GH-releasing hormone (GHRH)-induced GH secretion in adult patients with nonendocrine diseases who were under daily immunosuppressive glucocorticoid therapy. Six normal subjects (four men, two women) and seven steroid-treated subjects (three men, four women) were studied. GHRH-induced GH secretion was evaluated during a 40-minute intravenous (i.v.) infusion of saline or porcine galanin (12.5 micrograms/min). During saline infusion, steroid-treated patients showed a blunted GH response to GHRH (GH peak, 8.1 +/- 2.8 micrograms/L), as compared with normal subjects (GH peak, 23.8 +/- 3.9 micrograms/L). During galanin infusion, the GH response to GHRH was significantly enhanced (GH peak, 46.6 +/- 9.4 micrograms/L, P less than .05), as compared with saline infusion in normal subjects. In contrast, galanin infusion did not enhance the GH response to GHRH (GH peak, 16.6 +/- 6.5 micrograms/L), as compared with saline infusion in steroid-treated patients. The area under the GH-response curves was also significantly (P less than .05) lower in steroid-treated subjects, as compared with normal subjects. Thus, galanin failed to normalize or enhance the GH response to GHRH in patients treated long-term with glucocorticoids. It can be hypothesized that galanin does not elicit GH secretion by decreasing hypothalamic somatostatin tone.
authors.affiliation: Clinica Medica, University of Brescia, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Giustina
authors.forename: A
authors.initials: A
authors.lastname: Girelli
authors.forename: S
authors.initials: S
authors.lastname: Bossoni
authors.forename: F
authors.initials: F
authors.lastname: Legati
authors.forename: M
authors.initials: M
authors.lastname: Schettino
authors.forename: W B
authors.initials: WB
authors.lastname: Wehrenberg
mesh_terms: D000328:Adult; D004334:Drug Administration Schedule; D005260:Female; D019004:Galanin; D005938:Glucocorticoids / Q000008:administration & dosage / Q000627:therapeutic use*; D013006:Growth Hormone / Q000097:blood / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D018377:Neurotransmitter Agents / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology*
chemical_list: D005938:Glucocorticoids; D018377:Neurotransmitter Agents; D010455:Peptides; D019004:Galanin; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone