Brain GABAB binding sites in depressed suicide victims.

Binding sites for gamma-aminobutyric acid, type B (GABAB), were measured in post-mortem brain samples (frontal cortex, temporal cortex, and hippocampus) from a group of suicide victims and a group of sex- and age-matched controls. Retrospective psychiatric diagnosis was performed, and only suicide victims with clear evidence of depression in the absence of symptoms of other psychiatric or neurological disorders were studied. There were no significant differences between depressed suicides and controls in the number or affinity of GABAB binding sites in the frontal or temporal cortex and no difference in GABAB binding (measured at two concentrations) in the hippocampus. Thirteen of the depressed suicides had not been prescribed antidepressant drugs recently, and none were found in their blood at postmortem. The number of GABAB binding sites in the frontal and temporal cortex and GABAB binding in the hippocampus did not differ significantly between these drug-free suicides and matched controls. The Kd was higher, however, in the temporal cortex of the drug-free suicides than in the controls. A significant negative correlation was found between age and the number of GABAB binding sites in the temporal cortex (on the basis of pooled data from suicides and controls). These results indicate that GABAB binding sites are unaltered in the brains of depressed suicide victims.