Molecular pharmacology of serotonin receptors

The serotonin system has long been thought to play a role at several steps in the cycle of alcohol abuse. Initial motivation may be triggered by anxiety, which may exhibit a serotonergic component (5-HT1A receptor). Alcohol can potentiate the opening of 5-HT3 receptor ion channels, and agents which elevate serotonergic tone, including serotonergic agonists, uptake inhibitors and releasers, have shown promise in assisting with recovery from alcoholism. In this review, recent advances in serotonin receptor research are presented, with a special emphasis on the impact and interpretation of molecular biological data. Genetic and pharmacological concepts of receptor subtypes are reviewed and related to a new classification system for the 14 currently recognized subtypes of serotonin receptors. The current and likely future impact on drug design of the molecular approach to serotonin receptors is discussed. Finally, the question of why there are so many serotonin receptor subtypes is examined, along with possible roles of multiple G protein and second messenger pathways, and their effect on conserved domains of these receptor proteins.