title: Comparative effect of clonidine and growth hormone (GH)-releasing hormone on GH secretion in adult patients on chronic glucocorticoid therapy.
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 effects of GH-releasing hormone (GHRH) and clonidine, an alpha-2-adrenergic agonist which increases GH secretion acting at the hypothalamic level with an unknown mechanism, on GH secretion in seven adult patients (3M, 4F) with non endocrine diseases and on daily immunosuppressive glucocorticoid therapy. Eleven normal subjects (7M, 4F) served as controls. Steroid-treated patients showed a blunted GH response to GHRH (GH peak 8.3 +/- 3 micrograms/L) with respect to normal subjects (GH peak 19.3 +/- 2.4 micrograms/L). The GH responses to clonidine were also blunted (p less than 0.05) in steroid-treated patients (GH peak 5.8 +/- 2.8 micrograms/L) with respect to normal subjects (GH peak 17.6 +/- 2.3 micrograms/L). No significant differences between the GH responses to GHRH and clonidine were observed either in steroid-treated or in normal subjects. Clonidine is not able to enhance GH secretion similar to GHRH in patients chronically treated with steroids. It can be hypothesized that clonidine does not elicit GH secretion decreasing hypothalamic somatostatin tone.
authors.affiliation: Cattedra di Clinica Medica, University of Brescia, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Giustina
authors.forename: M G
authors.initials: MG
authors.lastname: Buffoli
authors.forename: A R
authors.initials: AR
authors.lastname: Bussi
authors.forename: M
authors.initials: M
authors.lastname: Doga
authors.forename: A
authors.initials: A
authors.lastname: Girelli
authors.forename: G
authors.initials: G
authors.lastname: Pizzocolo
authors.forename: A
authors.initials: A
authors.lastname: Pozzi
authors.forename: W B
authors.initials: WB
authors.lastname: Wehrenberg
mesh_terms: D000328:Adult; D003000:Clonidine / Q000494:pharmacology*; D005260:Female; D005938:Glucocorticoids / Q000009:adverse effects* / Q000627:therapeutic use; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D008297:Male; D016037:Single-Blind Method
chemical_list: D005938:Glucocorticoids; D007166:Immunosuppressive Agents; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D003000:Clonidine