Galanin is a neuropeptide that has not been established as a member of any known family of neuropeptides despite repeated efforts to discover related peptides. Its actions are mediated via Gi-protein-coupled receptors and ion channels, usually producing inhibition of secretion of a transmitter or hormone in the nervous and endocrine system. In many respects, these inhibitory actions of galanin remind us of those of gamma-aminobutyric acid (GABA) and of neuropeptide Y (NPY). Galanin coexists with GABA, noradrenaline, 5-hydroxytryptamine (5-HT), and NPY in several regions of the brain.