HIGH-AFFINITY [3H]IMIPRAMINE AND [3H]PAROXETINE BINDING-SITES IN SUICIDE BRAINS

Specific binding of [3H]imipramine and [3H]paroxetine was simultaneous ly examined in human brains (frontal cortex, temporal cortex, cingulat e cortex, hypothalamus, hippocampus and amygdala) from 11 controls and 11 depressed suicide victims. A single saturable high affinity site w as obtained for both radioligands. Age was not related to significant changes in [3H]imipramine and [3H]paroxetine binding parameters, which indicates the stability of the brain serotonergic system with increas ing age. A major finding of the present study concerns the existence o f a significant decrease in the maximum number (Bmax) of [3H]imipramin e binding sites in hippocampus from depressed suicides as compared wit h the control group, without changes in the binding affinity (Kd). In contrast, when [3H]paroxetine was used as radioligand, no changes in e ither Bmax or Kd were detected in any of the brain regions studied. Th ese findings suggest that [3H]imipramine may be a better marker than [ 3H]paroxetine when alterations in the presynaptic serotonergic uptake site are to be detected.