[Effect of fluoxetine treatment on serotonin and MHPG in 32 patients with major depressive disorder].

Considering the concept that depressive disorders were not only resulting from activity of one neurotransmitter, possible interactions between the noradrenergic system and a selective serotonin uptake inhibitor, fluoxetine, were investigated in order to test the hypothesis of noradrenergic or serotonergic involvement in depression. So the biological parameters (plasma and urinary MHPG, platelet serotonin) were evaluated by HPLC. The aim of this study was to evaluate the correlations between the concentrations of MHPG and serotonin in 32 melancholic patients treated by fluoxetine (20 mg/day) during a minimum of three weeks. The clinical examination with evaluation of the antidepressant effect carried out using the HDS/MES rating scale, allowed to divide the patients into three groups: responders to treatment, partial responders and non responders. In the same time, a control group of healthy subjects was investigated. ANOVA applied to platelet serotonin at day 0 showed a tendency toward heterogeneity between the three patient groups and the control group. The concentrations of serotonin in the three patients groups were highly reduced after 21 days of treatment. Concerning plasma and urinary MHPG there was non significant difference among the three patients groups at day 0 and the control groups. After treatment by fluoxetine, the results suggest that the urinary sulfate MHPG is an indicator of the metabolism of brain norepinephrine and seems to be a better turnover indicator than the plasma sulfate MHPG. The selective evaluation of sulfate and glucuronide MHPG could give a better survey of the psychobiological state of the patients than the total MHPG evaluation.