Chapter 6 Association of 5-HT 1 A Receptors with Affective Disorders

Serotonin or 5-hydroxytryptamine (5-HT) is synthesized in both the brain and peripheral system, which exert their actions at a wide family of receptors classified as 5-HT 1 to 5-HT 7 . Pharmacological, behavioral, and clinical studies involve particularly to the 5-HT 1A receptors (5-HT 1A -R) auto-receptors (presynaptic) and heteroreceptors (postsynaptic) in the control of motivated behavior, and consequently in the physiopathology of affective disorders and in the action mechanism of antidepressant drugs. In this way, some research support that 5-HT 1A -R participates in the delayed effect of different types of antidepressants, including selective serotonin reuptake inhibitors (SSRIs), and tricyclic drugs, principally. The therapeutic effect of serotonergic drugs as the SSRIs, starting with the binding to auto-receptors, which produces increases of 5-HT in the synaptic cleft as consequence of blockade of serotonin reuptake. While these molecular events occur initially, in the long-term are produced plastic changes at neuronal level, as well as down-regulation of the 5-HT 1A -R, which is associated with the therapeutic effects of antidepressant drugs. The purpose of this chapter is to analyze and discuss the current information about of 5-HT 1A -R-mediated signaling cascades, the intracellular signaling of 5-HT 1A -R, in addition to their expression and pharmacology that are important to treatment of affective disorders symptoms.