Serotonin in Central Cardiovascular Regulation: Ex Uno Plura (From One Comes Many)

Abstract Receptor distribution : Serotonin (5-HT; 5HT; 5-hydroxytryptamine) is a ligand that achieves an astonishing diversity of actions through its effects on at least 15 different receptors. All but one of the serotonin receptors are G-protein coupled as discussed extensively elsewhere in this book. Activation of some serotonin receptors leads to cell excitation, whereas others cause inhibition. Here, I will assess the role played by serotonergic systems in the rostral ventrolateral medulla, rostroventromedial medulla, and spinal sympathetic cell groups that affect blood pressure. Possible roles in psycho-affective disorders and autonomic functions that are clearly important, but do not affect blood pressure, will only be mentioned parenthetically. For an initial summary of the pharmacology of the 5-HT receptor family, I strongly recommend the Guide to Receptors and Channels, which is published and updated by the British Journal of Pharmacology and in Pharmacological reviews. The section on 5-HT currently lists seven main receptors, but in addition, several of these have subtypes. Some subtypes are present in some species but not others. For example, there are five types of 5HT1x receptor, although some have confusing duplicate names; 5HT1F receptor, 5HT1Eβ receptor, and 5HT6 receptor are all the same. All five 5HT1 receptors operate Gi/o as their principal transduction system, preventing the formation of cAMP, and are therefore inhibitory. The rest of this chapter will focus on the role of serotonin in the nervous system of the cardiovascular system.