Prolactin response to D-fenfluramine in outpatients with major depression.

There is much indirect evidence of serotonin abnormalities in patients with major depression. Unfortunately, previous reports of serotonin challenge studies in depressed patients have yielded conflicting results. In order to test the serotonin hypothesis of depression, the authors compared 20 outpatients with major depressive disorder to 20 normal control subjects using prolactin response to D-fenfluramine as a measure of central serotonergic (5-HT) functioning. Patients were free of histories of suicidal behavior and had no Axis II disorders. There were no significant differences in prolactin responses between depressed patients and control subjects to challenge with D-fenfluramine at a dose of 0.5 mg/kg. The possible implications of these findings are discussed with respect to theories regarding biological vulnerabilities to major depression.