Plasma-free and sulfoconjugated MHPG in major depressive disorders: differences between responders to treatment and...

The plasma levels of free and sulfoconjugated forms of 3-methoxy-4-hydroxyphenylglycol (MHPG) were examined before and after treatment in 16 patients with unipolar major depressive disorders without melancholia. The patients were treated with intravenous administration of clomipramine for 4 weeks. Seven depressive disorder patients who showed marked improvement (the improvement group) revealed significant reduction in their plasma sulfoconjugated MHPG levels. In 6 depressive disorder patients who showed no improvement (the no-improvement group), the plasma sulfoconjugated MHPG levels showed no significant change after treatment. The remaining 3 patients, who showed ambiguous change after treatment, were excluded from the analysis. Levels of plasma-free MHPG showed significant change after treatment in neither the improvement group nor in the no-improvement group. It is suggested that levels of plasma sulfoconjugated MHPG may serve as an indicator of brain noradrenergic activity.