Neuronal and behavioral plasticity: the role of serotonin and BDNF systems tandem.

INTRODUCTION: Serotonin (5-HT) and brain-derived neurotrophic factor (BDNF) are known as principal players in different kinds of plasticity. The 5-HT-BDNF interaction in early ontogeny and in adult brain is an intriguing problem. Area covered: This paper concentrates on the interaction between 5-HT and BDNF systems and its implication in different plasticity levels, from neurons to behavior. This review describes (1) different 5-HT functioning in the embryonic (as neurotrophin) and adult brain (as a neurotransmitter); (2) BDNF as a modulator of 5-HT system and vice versa; (3) the prolonged positive effect of BDNF on genetically and epigenetically defined central nervous system disorders; (4) The 5-HT-BDNF interplay contribution to aggressive behavior, depression, drug addiction, suicide, and stress response; and (5) the role of common second messengers for 5-HT and BDNF signaling in the 5-HT-BDNF interaction. Expert opinion: Dysregulation in 5-HT-BDNF interaction may be responsible for development of neuropsychiatric and behavioral abnormalities. 5-HT-BDNF cross-talk is a potential target for the treatment of various neurological diseases. Understanding the function of the members of BDNF system in response to challenges of the environment and the interaction with different 5-HT receptors in health and disease will one day lead to new classes of drugs.