Social Behavior and Serotonin

Serotonin (5-hydroxytryptamine, 5-HT) is implicated in the regulation of a wide range of social behaviors, including interpersonal aggression. Earlier studies investigating the role of 5-HT in aggression relied on the measurement of levels of the 5-HT metabolite 5-hydroxyindoleacetic acid (5-HIAA), and in later animal studies applied sophisticated pharmacological manipulations. With advances in molecular genetic techniques, the field has recently begun to focus on the genetic basis of individual differences in aggression. This chapter reviews studies of genetically modified animals and of gene polymorphisms in humans, with a particular focus on receptor genes, and gene polymorphisms located within the serotonin transporter (5-HTT), monoamine oxidase A (MAOA) and tryptophan hydroxylase 2 (TPH2) genes. We will also highlight recent imaging genetics studies and interactions with other genes and environmental factors, in order to point to promising future research approaches on the effects of serotonin on social behavior.