Abstract
In this paper we present the up-to-date knowledge on the mechanisms of action of selective serotonin reuptake inhibitors (SSRIs) and their use in anxiety disorders. Furthermore, we describe changes in serotonergic, GABAergic, peptidergic (CCK), adrenergic and dopaminergic systems along with changes in the RPA axis, observed both in animal and human studies, after the administration of SSRIs. Finally, we discuss the influence of SSRIs on Fos expression in different brain areas.