Galanin (1-13) – Neuroscience Peptides

Galanin is a widely distributed neuropeptide in the central nervous system (CNS), peripheral regions and endocrine system. Galanin has a role in energy homeostasis. Central injections of galanin to the amygdala led to food intake in rats. Galanin also acts in the CNS to inhibit neurotransmitter release, such as acetylcholine. Galanin has been implicated in numerous neurological conditions, including Alzheimer’s disease, depression, and epilepsy. Galanin interacts with 3 receptor subtypes, GalR1-3 which are G protein-coupled receptors inserted into the plasma membrane. GalR1 is believed to activate a Gβγ pathway to regulate MAPK activation. GalR2 can also activate the MAPK pathway, but unlike GalR1, there is detectable inositol phosphate production. GalR3 is associated with the Galphai/o pathway. Activation of the receptor leads to a cellular influx of potassium ions. The galanin active N-terminal fragment (1-16) has been identified as a highly potent agonist for the galanin receptors. This has become a basis for galanin-based peptides, which are neuroactive. These are being investigated as a potential source for anticonvulsant neuropeptides as a therapeutic for conditions such as epilepsy. A library of galanin fragments has allowed screening of their properties to be assessed. Galanin fragments have different affinities for GalR receptors. Galanin (1-13) has been shown to act as a high-affinity receptor antagonist in competitive receptor displacement tests using rats. Numerous chimeric peptides have been generated with galanin (1-13) to generate peptides for studying galinergic signalling. Examples of chimeric peptide tools used with galanin (1-13) are the neuropeptide Y fragment (named M32) and a bradykinin fragment (called M35).