Increased [3H] raclopride binding sites in postmortem brains from schizophrenic violent suicide victims

The specific binding of the D2-dopamine receptor antagonist radioligand [3H] raclopride was quantitated in the postmortem caudate and frontal cortex from schizophrenic suicide victims and control subjects. In schizophrenic suicides the density of binding sites (Bmax) was higher (40%, P < 0.05) in the caudate, whereas it did not change in the cortex as compared to those in controls. The apparent dissociation constants (KD) were also found increased both in caudate (24%) and cortex (75%) from schizophrenics, but these apparent decreases in receptor affinity did not reach statistical significance. The mean Bmax value in drug-free schizophrenic suicides (n = 3) did not differ from the Bmax value in neuroleptic drug-treated schizophrenics (n = 7) but it was found increased in respect to control subjects (n = 9). No differences in [3H] raclopride binding were observed between non-schizophrenic suicide victims (n = 4) and matched controls (n = 4), suggesting that the modifications of D2-dopamine receptors in schizophrenia are not related to suicide.