Abstract (1) The administration of gamma-hydroxybutyrate (GHB) has no effect on the hypothalamic concentration of norepinephrine (NE), dopamine (DA) and serotonin (5-HT) in the rat. (2) The injection of GHB induces a consistent growth hormone (immunoreactive GH) secretory episode, followed by basal levels for several hr. (3) During this period, the infusion of clonidine, an α-adrenergic agonist, elicits a dramatic GH increment, whereas basal levels are not modified by isoproterenol, a β-adrenergic agonist. (4) In animals pretreated with α- and β-adrenergic agonists, clonidine enhances the GH peak induced by GBH, which is clearly inhibited by isoproterenol. The effects of α- and β-adrenergic antagonists were also investigated in this study. (5) The data reported here could support the hypothesis that α-adrenergic receptors mediate the secretion of the GH-releasing hormone and that β-adrenergic receptors are involved in the release of somatostatin.