Subtype selective activation and molecular characterization of galanin receptors

Sammanfattning: Showing an extensive distribution in the nervous system, and often in co-localization with the classical neurotransmitters, neuropeptides are functioning as important modulators of neuronal signaling. Subsequently, compelling evidence has implicated a modulatory role for the neuropeptide galanin in several physiological functions. The effect of galanin is trancduced intracellularly by three different receptors, and defining the explicit effect from these receptor subtypes is of outmost interest, and likely to result in future therapeutic utilization of the galanin system.The main aim of this thesis was to improve the development of subtype selective ligands utilized to differentiate between the galanin receptor subtypes. To achieve this, we have designed and developed novel galanin receptor ligands and characterized the molecular interactions necessary for ligand bindig at the GalR2 subtype.The major findings include the introduction and characterization of two galanin receptor ligands, selectively activating GalR1 or inhibiting GalR2. Although having moderate selectivity, the two ligands have been utilized in a number of studies, pursuing their initial presentation, in order to differentiate between the galanin receptors and to establish their specific function. Further optimization is likely to improve the selectivity and utilization of these ligands. By identifying the major pharmacophores in the Gal(2-11) ligand and the residues in the GalR2 subtype participating in ligand binding, we have been able to characterize the binding site in this receptor subtype and interactions that are of significance for recognition of subtype specific ligands. Together, these findings on GalR2 and Gal(2-11) are of importance for future design of ligands acting on this receptor.