HALOPERIDOL BLOCKS THE UPTAKE OF [F-18] N-METHYLSPIROPERIDOL BY EXTRASTRIATAL DOPAMINE-RECEPTORS IN SCHIZOPHRENIC-PATIENTS

We had previously demonstrated extrastriatal uptake of[F-18]N-methyl-s piroperidol (F-18-NMS) in the human brain. This study evaluates the ef fect of haloperidol on F-18-NMS binding in extrastriatal brain regions . Six schizophrenic patients on haloperidol underwent two PET scans wi th F-18-NMS at 12 h and at 6 days after haloperidol withdrawal. There was a significant increase in F-18-NMS uptake in striatal, thalamic, a nd temporal regions but not in frontal, occipital, or cerebellar regio ns, following drug withdrawal. Haloperidol's ability to block the upta ke of F-18-NMS is an indication of the specificity of the radioligand' s binding in these regions and supports the postmortem data demonstrat ing the presence of dopamine D-2 receptors in the thalamus and tempora l cortex of the human brain. (C) 1995 Wiley-Liss, Inc.