UP-REGULATION OF THE PLATELET SEROTONIN(2A) RECEPTOR AND LOW BLOOD SEROTONIN IN SUICIDAL PSYCHIATRIC-PATIENTS

Suicidality has been found to be associated with low pre- and postsyna ptic serotonin functioning. The purpose of this study was to examine w hether in acutely suicidal psychiatric inpatients, the blood serotonin concentration was related to the underlying psychiatric disorder and whether it was associated with changes in the affinity (dissociation c onstant, KD) or in the maximal binding capacity (B-max) of the platele t serotonin(2A) receptor. We therefore determined the blood serotonin concentrations and the platelet serotonin(2A) receptor activities of 4 5 suicidal psychiatric patients and 20 healthy subjects. We found that the blood serotonin concentrations were significantly lower in suicid al patients compared to healthy subjects. In all diagnostic categories (affective disorder, schizophrenia and adjustment disorder) we noted a significantly higher maximal binding capacity of the platelet seroto nin(2A) receptor. These findings support the notion that a reduction i n the availability of serotonin and an upregulation of the serotonin(2 A) receptors in psychiatric patients are associated with a loss of con trol over suicidal impulses.