GALANIN RECEPTOR SUBTYPES AS POTENTIAL THERAPEUTIC TARGETS

Galanin is a widely distributed mammalian neuropeptide that modulates many physiological processes. Galanin elicits its diverse physiologica l effects by interacting with at least three distinct G protein-couple d receptors known as the GalR1, GalR2 and GalR3 receptors. All three o f these galanin receptors have been cloned and expressed in heterologo us cells, and patent applications claiming each of the three galanin r eceptor subtypes have been filed by various pharmaceutical companies. These patent applications generally claim the use of galanin receptor subtypes for the discovery of selective agonists and antagonists via s tandard screening paradigms. The three known galanin receptor subtypes are differentially expressed in central and peripheral tissues and ha ve distinct pharmacological properties. This review discusses the stru cture, function, pharmacological properties and potential physiologica l roles of each of the three galanin receptor subtypes. Although no po tent and selective galanin receptor ligands have been disclosed to dat e, the possible therapeutic utility of GalR1, GalR2 and GalR3 receptor agonists and antagonists is also discussed.