5-HT uptake sites and 5-HT2 receptors in brain of antidepressant-free suicide victims/depressives: increase in 5-HT2 sites in cortex and amygdala.

The density (Bmax) of 5-HT2 receptors labelled with [3H]ketanserin was significantly increased in prefrontal cortex (by 67%) and amygdala (by 97%) from suicide/depressives in comparison with controls. There were no differences in Kd of [3H]ketanserin binding between the two groups. The density (Bmax) and affinity (Kd) of [3H]paroxetine sites were not significantly different in the suicide/depressives and controls. The ratio between the density of presynaptic 5-HT uptake sites and postsynaptic 5-HT2 receptors in amygdala was significantly lower in suicide/depressives than in controls. The data confirm and extend some of the previous findings of increases in 5-HT2 receptors in post-mortem brains of suicide victims and depressives who died of natural causes and lend support to the view that an abnormality in brain serotonergic system is associated with depression and suicidal behaviour.