Nocturnal serum melatonin in major depressive disorder before and after desmethylimipramine treatment

The major finding from the studies of untreated depressives was reduced nocturnal concentrations of serum melatonin when patients with major depressive disorder, melancholic subtype, were compared to major depressives without melancholia or healthy controls. In our study, an association between symptoms of melancholia and DST nonsuppression was noted. The results obtained in the subset of depressed patients treated with DMI were different from those previously found in rats treated with he same antidepressant. One plausible explanation for the difference between results of the rat and human studies might be the lower concentration of DMI in plasma in the current study (70 ± 9 ng/ml) compared to rats (347 ± 75 ng/ml).