Characterization of the stimulatory effect of galanin on growth hormone release from the rat anterior pituitary.
The present study was undertaken to investigate the direct actions of rat galanin (R-GAL) on growth hormone (GH) release from the rat anterior pituitary in vitro. R-GAL modestly but significantly stimulated GH release without an increase in intra- and extracellular cyclic AMP levels in monolayer cultures of rat anterior pituitary cells. This stimulatory effect of R-GAL was dose-dependent but not additive with that of GH-releasing factor (GRF). R-GAL-stimulated GH release was less sensitive to the inhibitory effect of somatostatin than was GRF-stimulated GH release. In perfusions of rat anterior pituitary fragments, R-GAL induced a gradual and sustained increase of GH release. Incremental GH release derived in part from preformed stored GH. These data confirm that R-GAL acts at the pituitary level to stimulate GH release by a mechanism distinct from that of GRF.
Sato
M
M
First Department of Internal Medicine, Kagawa Medical School, Japan.
Takahara
J
J
Niimi
M
M
Tagawa
R
R
Irino
S
S
D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D019004:Galanin; D013006:Growth Hormone / Q000378:metabolism*; D008297:Male; D010455:Peptides / Q000494:pharmacology*; D010903:Pituitary Gland, Anterior / Q000033:anatomy & histology / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013004:Somatostatin / Q000494:pharmacology; D013268:Stimulation, Chemical; D013552:Swine; D013997:Time Factors
D010455:Peptides; D013004:Somatostatin; D019004:Galanin; D013006:Growth Hormone