Synthesis of BDNF by administration of antidepressants. Antidepressant drugs, in addition to promoting an increase in serotonin activity in the synaptic cleft, also promote the synthesis and consequent release of BDNF by the cell, which culminates in several cellular changes triggering the improvement or remission of depressive symptoms. TH: tryptophan hydroxylase; AADC: aromatic L-amino acid decarboxylase; 5-HT: 5-hydroxytryptamine or serotonin; SSRI: selective serotonin reuptake inhibitors; 5-HTR: 5-hidroxy-triptamin receptor; TrkB: tropomyosin type B kinase activity; BDNF: brain-derived neurothrophic factor; GC: golgi complex; RER: rough endoplasmic reticulum; mRNA: messenger ribonucleic acid.