Plasma prolactin response to d-fenfluramine in obsessive-compulsive patients before and after fluvoxamine treatment

The prolactin (PRL) responses to oral d-fenfluramine (30 mg) and placebo were assessed in 13 patients with obsessive-compulsive disorder (OCD) and in matched healthy subjects. After the neuroendocrine test, all patients were treated with fluvoxamine maleate (150-300 mg/day). At the end of the 10th week of treatment, 10 patients underwent again the neuroendocrine assessment. In drug-free patients, the PRL response to d-fenfluramine was significantly lower than in the comparison group. After 10-week fluvoxamine treatment, the PRL response to the serotonergic agent normalized. These findings suggest that, at least at the neuroendocrine level, central serotonergic responsivity is reduced in drug-free OCD patients, and that long-term fluvoxamine administration is associated with its normalization.