FUNCTIONAL-CHARACTERISTICS OF HETEROLOGOUSLY EXPRESSED 5-HT RECEPTORS

Over the past 10 years, molecular cloning has revealed the presence of 15 serotonin (5-hydroxytryptamine; 5-HT) receptor subtypes, which can be subdivided in seven subfamilies. Except for the 5-HT3, receptors, which are ligand-gated ion channels, all 5-HT receptors belong to the superfamily of G-protein-coupled receptors. The large multiplicity of 5-HT receptor subtypes has been suggested to lie a direct result of th e evolutionary age of the 5-HT system, Molecular information on G-prot ein-coupled 5-HT receptors is: currently available for several mammali an species as well as for a limited number of invertebrate species (in sects, molluscs), The aim of this review is to give an overview of all cloned 5-HT receptor subtypes belonging to the superfamily of G-prote in-coupled receptors with specific emphasis on the pharmacological and signaling properties of the receptors upon expression in several hete rologous expression systems. (C) 1997 Elsevier Science B.V.