The effects of antidepressant drugs belonging to different pharmacological groups--amitriptyline, fluoxetine (prozac), and tianeptine (coaxyl)--on the content of monoamines and their metabolites in Wistar rat brain structures (frontal cortex, hypothalamus, nucleus accumbens, striatum, and hippocamp) has been studied using HPLC with electrochemical detection. Tricyclic antidepressant amitriptyline (10 mg/kg) was found to produce a moderate increase in the DOPAC/dopamine turnover index in nucleus accumbens, but did not influence the levels of serotonin (5-HT), dopamine, and its metabolites (5-HIAA, DOPAC, and HVA) in other brain structures studied (frontal cortex, hypothalamus, striatum, hippocamp). Fluoxetine (Prozac) (20 mg/kg) decreased both the 5-HIAA content and the 5-HIAA/5-HT (5-HT turnover index) in all brain structures of Wistar rats. In contrast, the effects of Prozac on the level of catecholamines and their metabolites in various brain regions was more complex. Tianeptine (Coaxyl) was demonstrated to increase both the 5-HIAA content and the 5-HIAA/5-HT ratio in all the structures studied (except for nucleus accumbens), in good agreement with the hypothesis concerning a two-phase mode of tianeptine action with enhanced 5-HT secretion in the synaptic gap in the first stage of pharmacological response.