5-HT2 receptor subtypes: a family re-united?

The current classification for 5-HT2 receptors accommodates three subtypes. In addition to the originally defined 5-HT2 receptor, sanctuary is now provided for the structurally related 5-HT1c receptor (now 5-HT2c) and at least one atypical 5-HT receptor subtype. The strong functional union of this family is reflected in the paucity of ligands that will discriminate between its subtypes and prompts some re-evaluation of the activities of compounds which may now be regarded as nonselective for the receptor subtypes in this class. In this article, Gordon Baxter and colleagues examine the pharmacology of both officially recognized and atypical 5-HT2 receptor subtypes. A number of novel selective agents are highlighted, some of which may prove useful for 5-HT2 receptor classification and, ultimately, clarify the mechanistic basis for current and future therapeutic strategies which target this receptor family.