No elevated D2 dopamine receptors in neuroleptic-naive schizophrenic patients revealed by positron emission tomography and [11C]N-methylspiperone.
The dopamine hypothesis of schizophrenia received strong support when a two- to three-fold elevation of D2 receptor densities was demonstrated by positron emission tomography (PET) and [11C]N-methylspiperone ([11C]NMSP). In the present study, the reproducibility of this finding was examined by application of a similar method in seven normal comparison subjects and seven neuroleptic-naive schizophrenic patients examined by PET before and after administration of haloperidol, 7.5 mg. After haloperidol, the specific binding of [11C]NMSP was reduced by 80-90%, resulting in a signal-to-noise ratio that was unfavorably low for reliable quantification. No significant difference was found between normal subjects and patients in a descriptive analysis of the time-activity curves or in a nonequilibrium graphical determination of D2 receptor densities in the basal ganglia. The results are consistent with those of a previous quantitative PET study of [11C]raclopride binding, which showed normal densities of D2 receptors in the striatum of neuroleptic-naive schizophrenic patients.
D000328:Adult; D002250:Carbon Radioisotopes; D002531:Cerebellum / Q000000981:diagnostic imaging / Q000187:drug effects / Q000503:physiopathology; D018491:Dopamine Agonists / Q000493:pharmacokinetics; D005260:Female; D005625:Frontal Lobe / Q000000981:diagnostic imaging / Q000187:drug effects / Q000503:physiopathology; D006220:Haloperidol / Q000009:adverse effects / Q000627:therapeutic use; D006801:Humans; D008297:Male; D011699:Putamen / Q000000981:diagnostic imaging / Q000187:drug effects / Q000503:physiopathology; D011869:Radioligand Assay; D017448:Receptors, Dopamine D2 / Q000187:drug effects / Q000502:physiology*; D015203:Reproducibility of Results; D012559:Schizophrenia / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000503:physiopathology; D012565:Schizophrenic Psychology; D013134:Spiperone / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D014055:Tomography, Emission-Computed
D002250:Carbon Radioisotopes; D018491:Dopamine Agonists; D017448:Receptors, Dopamine D2; D013134:Spiperone; C039167:3-N-methylspiperone; D006220:Haloperidol