Serotonin function in detoxified heroin abusers: prolactin and cortisol responses to fenfluramine challenge.

The function of the central serotonergic system was examined indirectly through the measurement of prolactin (PRL) and cortisol responses to fenfluramine challenges in 27 heroin addicts 2 months after detoxification and in nine healthy volunteers. Heroin abusers included nine addicts with comorbid depressive disorders (Group A), nine with aggressive behavior and antisocial personality (Group B), and nine with heroin addiction uncomplicated by other Axis I and II psychiatric disorders (Group C). PRL and cortisol responses of patients in Group A were blunted, while those of patients in Groups B and C did not differ from those of the healthy volunteers. Cortisol responses in Group A differed significantly from those in the other patient groups and in the normal comparison group for AUC analyses, but the diagnosis x time interaction showed a significant difference only between Group A and the normal group. Our data suggest that the function of the serotonergic system is impaired in heroin addicts with comorbid depression but not in heroin addicts who are not clinically depressed. Thus, the serotonergic system does not appear to be impaired by prolonged opioid exposure, per se.