RESUMEN
Serotonin (5-HT) is, from a filogenetic point of view, one of the older neurotransmitter. It has been isolated more than 40 years ago. But only less than 5 per cent belongs to central 5-HT. In the 60's researchers focused their works on the intracellular processes (synthesis, storage, re-uptake, catabolism and the role of the enzime Tryptophane-hydroxilase). They also described some serotonin EEG effects. In the 70's the role of other aminoacids inhibiting Tryptophan, and therefore 5-HT synthesis, was studied. But it is in the early 80's when the 5-HT receptors and the second messanger mechanisms began to draw their attention. There are at least seven 5-HT receptors described until 1994, each one of them with several subtypes. Clinical uses of their agonists and antagonists appear to be useful in many psychiatric disorders. This paper makes a review of the 5-HT receptor Arboretum and its clinical implications, and the participation of the neurotransmitter in affective and anxiety disorders, phsychosis and other CNS illnesses. We also wanted to examine the use of SSRI and inespecific serotonin reuptake inhibitors, atypical antipsychotics with serotonin mechanisms of action, and other serotonergic drugs acting on migraine, aggressive behavior, eating disorders, adictions and dementia.