Characterization of the stimulatory effect of galanin on growth hormone release from the rat anterior pituitary

Abstract

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 senstive to the inhibitory effect of somatostatin than was GRF-stimulated GH release. In perifusions 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.