BENZODIAZEPINE RECEPTORS IN THE POSTMORTEM BRAIN OF SUICIDE VICTIMS AND SCHIZOPHRENIC SUBJECTS

To examine the role of benzodiazepine (BZ) receptors in suicide and sc hizophrenia, we determined BZ receptors in post-mortem brain (Brodmann 's area 10) obtained from suicide victims, schizophrenic patients, and control subjects using [H-3]RO15-1788 as the radioligand. The maximum number of binding sites (B-max) of BZ receptors in the cortex of suic ide victims was significantly higher compared with controls, but this increase was mainly due to those suicide victims who died by violent m eans and whose B-max was significantly higher than of those who died b y non-violent means or control subjects. In schizophrenic patients, B- max was not significantly different from that of control subjects. Whe n the schizophrenic subjects were separated into two groups, those on neuroleptics and those off neuroleptics for at least 12 months, howeve r, the mean B-max of BZ receptors in the prefrontal cortex in post-mor tem brain obtained from schizophrenic patients on neuroleptics was sig nificantly lower than B-max in drug-free schizophrenic patients or nor mal controls. There were no significant differences among groups in va lues of the apparent dissociation constant (K-D) of [H-3]RO15-1788 bin ding. These results suggest that BZ receptors are up-regulated in the cortex of suicide victims, specifically those who used violent means, and that neuroleptic treatment may result in decreased central BZ rece ptor binding in the cortex of schizophrenic patients. Thus, the method of suicide and previous exposure to neuroleptics should be considered in the interpretation of data on BZ receptors. (C) 1997 Elsevier Scie nce Ireland Ltd.