PLATELET SEROTONIN-2A RECEPTORS - A POTENTIAL BIOLOGICAL MARKER FOR SUICIDAL-BEHAVIOR

Objective: Abnormalities in the serotonergic system have been implicat ed in suicidal behavior. Higher numbers of serotonin-2 (5-HT2) recepto rs have been reported in the post-mortem brain of suicide victims. In order to further examine the role of 5-HT2A receptors in suicidal beha vior, the authors studied 5-HT2A receptors in platelets of suicidal an d nonsuicidal patients as well as normal comparison subjects. Method: 5-HT2A receptor levels were determined by using [I-125]LSD as a radiol igand in platelets obtained from hospitalized psychiatric patients (N= 131) and nonhospitalized normal comparison subjects (N=40) during a dr ug-free baseline period. Patients were diagnosed according to DSM-III- R criteria, and suicidal behavior was identified by using the Hamilton Depression Rating Scale. Results: The mean maximum number of binding sites (B-max) of platelet 5-HT2A receptors for all suicidal patients r ues significantly higher than for nonsuicidal patients or normal compa rison subjects. This significant difference remained when subgroups of suicidal patients with depression, schizophrenia,, schizoaffective di sorder, or bipolar illness were compared to the other two subject grou ps. The higher number of platelet 5-HT2A receptors in suicidal patient s was independent of diagnosis. While there was no significant differe nce in B-max between patients with serious suicidal ideation and these who made suicidal attempts, both groups had significantly higher B-ma x than normal comparison subjects. Conclusions: The observed higher nu mber of platelet 5-HT2A receptors in suicidal patients is independent of diagnosis and appears to be associated with both the brain and the platelets of suicidal patients. These results thus suggest the potenti al usefulness of platelet 5-HT2A receptors as a biological marker for identifying suicide-prone patients.