Perspective Higher-End Serotonin Receptors: 5-HT5, 5-HT6, and 5-HT7

Serotonin (5-hydroxytryptamine, 5-HT; 1) is a major neurotransmitter that is believed to produce many of its effects via interaction at seven populations of 5-HT receptors, 5-HT1 to 5-HT7, and the serotonin transporter (SERT). Serotonin was discovered in the late 1940s, and the first 5-HT receptors were identified in the periphery shortly thereafter. It was in the 1970s that 5-HT binding sites were definitively identified in the brain, and in 1979 two populations of receptors, 5-HT1 and 5-HT2 receptors, were proposed (reviewed in ref 1). Over the ensuing decade or so, by use of techniques such as radioligand binding to brain homogenates, autoradiog-raphy, and molecular biology, seven families of 5-HT receptors were described.2 Some families consist of multiple subpopulations, excluding splice variants an