Human galanin, a 30-amino acid non-amidated peptide, has originally been isolated from colon and pituitary. Its sequence differs from that of rat and porcine galanins by 4 and 6 amino acids in the C-terminal moiety, respectively. Synthetic human galanin is equipotent to the rat peptide in the isolated rat fundus muscle strip bioassay. Both peptides also fully activate the rat galanin receptor, indicating the importance of the conserved N-terminal portion of galanin for receptor interaction. Galanin, which is widely distributed in the CNS, and GAL receptors (GALR) are overexpressed in limbic brain regions associated with cognition in Alzheimer disease. As galanin inhibits acetylcholine release, galanin antagonists have gained interest in AD research.