The Serotonergic System and Its Role in Thermoregulation

Serotonin (5-hydroxytryptamine—5-HT) is an important neurotransmitter that exerts a remarkably large array of biological roles in the central nervous system and at the body level. It is involved in generating emotions, being a natural mood stabilizer; it reduces depression, anxiety, modulates sleep, and has many other effects. It is also involved in fetal and postnatal brain development. This variety of biological effects, particularly in the central nervous system, with influence on behavior and cognitive functions, relies on a large number of pre- and postsynaptic serotonin receptor (5-HTR) isoforms spread throughout the brain. They can be grouped in seven large families and include over 18 subtypes, identified based on gene sequences, expression patterns, and pharmacological responses. While in vertebrates these receptors have been properly characterized and described, their correspondents in invertebrates have been far less explored, despite the assumption that they may have similar properties to those described in vertebrates. This paper summarizes the current knowledge in several important areas that together define the entire scope of serotonin receptor research, with a particular emphasis on the role of serotonergic central pathways and circuitry in thermoregulation and correlations with neurologic and psychiatric pathology.