Serotonin (5-hydroxytryptamine, 5-HT) receptors are a family of guanine nucleotide triphosphate-binding protein-coupled receptors and one ligand-gated ion channel that transduce an extracellular signal by the neurotransmitter 5-HT to an intracellular response. These receptors are involved in a myriad of physiological functions. As many neuronal, physiological, and behavioral processes are influenced by 5-HT receptors, it is not surprising that dysfunction and regulation of 5-HT receptors are implicated in numerous disorders and disease states. Therefore, understanding 5-HT receptor second messenger systems, their effector linkage, the multiplicity of coupling pathways, and how these pathways are regulated is critical to disease etiology and therapeutic discovery.
