Galanin receptors and their therapeutic potential

Galanin, a 29 - 30 amino acid neuropeptide, is widely distributed in both the central and peripheral nervous systems. The peptide is unique to other families of neuropeptides and is highly conserved in the N-terminal portion among several mammalian species. Cloning efforts have successfully yielded three galanin receptor (GalR) subtypes that have high affinities for galanin. A recently isolated galanin-like peptide has high affinity for at least one of the three receptors. Galanin modulates a variety of physiological processes via activation of these receptor subtypes. In the CNS, galanin alters the release of several neurotransmitters. For example, it has an inhibitory effect on the release of acetylcholine (ACh) in the hippocampus, suggesting a potential role in the modulation of memory and learning. When injected directly into the ventricles of the brain, galanin increases food intake and alters plasma levels of hormones involved in the maintenance of nutrient and body weight homeostasis. The peptide a...