Biphasic Action of Reserpine and Isocarboxazid on Behavior and Serotonin Metabolism

Abstract

In longitudal studies on psychiatric patients receiving therapeutic doses of reserpine and isocarboxazid, singly or in combination, we observed that the aggravation of psychotic symptoms sometimes occurring during treatment with reserpine was associated with a marked rise in urinary 5-hydroxyindoleacetic acid. Tranquilization was accompanied by a more moderate increase under the influence of reserpine, or by a reduction of 5-hydroxyindoleacetic acid excretion while on monoamineoxidase inhibitor medication. It is concluded that a moderate rise of free serotonin in the brain is associated with tranquilization, while a greater increase is accompanied by excitation.