TY - JOUR T1 - Transmembrane Signaling in the Brain by Serotonin, A Key Regulator of Physiology and Emotion JF - Bioscience Reports JO - Biosci Rep SP - 363 LP - 385 DO - 10.1007/s10540-005-2896-3 VL - 25 IS - 5-6 AU - Adayev, Tatyana AU - Ranasinghe, Buddima AU - Banerjee, Probal Y1 - 2005/10/12 UR - http://www.bioscirep.org/content/25/5-6/363.abstract N2 - Serotonin (5-HT) is an ancient chemical that plays a crucial functional role in almost every living organism. It regulates platelet aggregation, activation of immune cells, and contraction of stomach and intestinal muscles. In addition, serotonin acts as a neurotransmitter in the brain and the peripheral nervous system. These activities are initiated by the binding of serotonin to 15 or more receptors that are pharmacologically classified into seven groups, 5-HT1 through 5-HT7. Each group is further divided into subgroups of receptors that are homologous but are encoded by discrete genes. With the exception of the 5-HT3 receptor-a cation channel—all of the others are G protein-coupled receptors that potentially activate or inhibit a large number of biochemical cascades. This review will endeavor to compare and contrast such signaling pathways with special attention to their tissue-specific occurrence, their possible role in immediate effects on covalent modification of other proteins, and relatively slower effects on gene expression, physiology and behavior. ER -