Effects of rat galanin and galanin message associated peptide (GMAP) on rat growth hormone secretion and stimulating effect of γ-aminobutyric acid on galanin release from rat hypothalamus

Abstract Immunoreactive galanin and galanin message associated peptide (GMAP) were detectable in rat hypothalamus in the concentration of 563±23 and 14.3±3.1 fmol/hypothalamus, respectively. γ -Aminobutyric acid (GABA) elicited a dose-related increase in galanin release from rat hypothalamic fragments, which was inhibited by picrotoxin, a GABA antagonist. Growth hormone (GH) secretion from rat anterior pituitary cells were stimulated by rat galanin, but not by GMAP. These findings suggest that hypothalamic galanin, but not GMAP, may play roles in GH secretion induced by GABAergic mechanisms in the rat.