Preface: Focus on the serotonin transporter

The serotonin transporter (SERT) has gained research popularity due to its prominent role in normal and aberrant brain processes. This key brain protein reuptakes serotonin from the synaptic cleft into presynaptic neurons, thereby modulating serotonergic neurotransmission. An entire class of psychotropic drugs, the serotonin reuptake inhibitors (SRIs), is dedicated to the action of this single protein. The fact that selective SRIs are becoming the world's most prescribed psychotropic medication emphasizes the utmost importance of SERT research for clinical psychiatry. The growing body of knowledge on SERT’s role in the brain also emphasizes the need for experimental models of SERT function. Collectively, this has stimulated the compilation of this book, the aim of which is to provide a comprehensive update spanning the breadth of SERT research from animal models to their clinical parallels. Although the exact functional mechanisms of SERT are not yet fully elucidated, it is thought to contain 12 hydrophobic transmembrane domains and to bind Na⁺, Cl⁻, and serotonin simultaneously. This results in a conformational change in the molecule, forming a barrier against the exterior of the cell, and opens the protein inwardly to the cytoplasmic membrane. The serotonin then disassociates from SERT, and the transporter returns to its original conformation receptive to extracellular serotonin once again. This process is the main mechanism of serotonin modulation in the brain, and the dysregulation of this system can affect brain and behavior markedly.