Norepinephrine Metabolism in Depressive Disorders: Implications for a Biochemical Classification of Depressions

The introduction of drugs (e.g., monoamine oxidase inhibitor antidepressants, tricyclic antidepressants and lithium salts) which proved to be effective in the treatment of depressive and manic disorders has had a major impact not only on clinical psychiatric practice but also on biological research in psychiatry. The neuropharmacology of these drugs has been studied extensively by a large number of investigators and the findings of these studies suggest that the effects of these drugs on the metabolism of the biogenic amines (i.e., the catecholamines, norepinephrine, and dopamine, as well as the indoleamine, serotonin) may be of importance clinically.1 These neuropharmacological findings served to stimulate considerable interest in biological research in the affective disorders, and many clues to the underlying pathophysiology of depressive and manic disorders have emerged from this research in recent years.2