title: Galanin counteracts the inhibitory effects of glucocorticoids on growth hormone secretion in the rat.
abstract: The aim of our study was to investigate the effect of galanin on baseline and growth hormone (GH)-releasing hormone (GHRH)-stimulated GH concentrations in conscious, freely moving rats receiving long-term glucocorticoid treatment. Animals were treated for 7 days with an intraperitoneal injection of either vehicle or dexamethasone ([dex] 40 micrograms/d). Rats underwent the following experimental trials: at -15 minutes animals received an intravenous injection of saline or galanin (12.5 micrograms/kg), and at 0 minutes rats received a second intravenous injection of saline or rat GHRH (500 ng/kg). Blood samples were drawn every 5 minutes from -15 to +15 minutes and then at 30 minutes. The GH response to saline + GHRH alone was significantly higher (P < .05) in chronically vehicle-treated rats as compared with chronically dex-treated ones. In contrast, galanin + saline increased serum GH levels in a similar fashion in both chronically vehicle- and dex-treated rats. The response to galanin + GHRH was similar to galanin + saline in chronically vehicle-treated rats, but was significantly enhanced in chronically dex-treated rats. These results suggest that galanin-mediated GH release in rats may involve somatostatinergic pathways.
authors.affiliation: Department of Health Sciences, University of Wisconsin-Milwaukee 53201.
authors.forename: A
authors.initials: A
authors.lastname: Giustina
authors.forename: D M
authors.initials: DM
authors.lastname: Voltz
authors.forename: J
authors.initials: J
authors.lastname: Teik
authors.forename: W B
authors.initials: WB
authors.lastname: Wehrenberg
mesh_terms: D000818:Animals; D003907:Dexamethasone / Q000494:pharmacology; D004347:Drug Interactions; D019004:Galanin; D013006:Growth Hormone / Q000097:blood*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D008297:Male; D010455:Peptides / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D010455:Peptides; D003907:Dexamethasone; D019004:Galanin; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone