EVOLUTIONARY ANCIENT ROLES OF SEROTONIN - LONG-LASTING REGULATION OF ACTIVITY AND DEVELOPMENT

Biogenic monoamines (catecholamines, indoleamines and histamine) are e volutionary old and important modulators of long-lasting changes in th e functional state of cells. They are found in many protozoans and in almost all metazoans. Monoamines preserve their evolutionary old funct ions (first of all being intracellular signals and later hormones and growth factors) even in those animals in which they acquired the funct ion of neurotransmitter. The older functions of serotonin, an importan t member of the family of indoleamines, are reviewed here. Described a re: presence of serotonin in organisms at various phylogenetic levels; its role in embryonal, foetal and postnatal development, especially i n the development of the central nervous system. It is concluded that in none of these functions serotonin is the only factor, but it is an ubiquitous and important modulator of a vast array of processes and fu nctions taking part in development and plasticity.