[3H]raclopride binding to brain tissue from subjects with schizophrenia: methodological aspects

The binding of [3H]raclopride to particulate membrane and frozen sections (with quantitative autoradiography) from the caudate-putamen, obtained at autopsy from schizophrenic and non-schizophrenic subjects, was measured. The affinity of [3H]raclopride to particulate membrane was significantly decreased in the schizophrenic compared to non-schizophrenic subjects. The density of [3H]raclopride binding to tissue from subjects with schizophrenia was increased, unchanged or decreased depending on the methodology used. Finally, there was an age-dependent decrease in [3H]raclopride binding in the frozen sections from the caudate-putamen of the non-schizophrenic subjects. This age-dependent decrease was not apparent using particulate membrane from schizophrenic or non-schizophrenic subjects or tissue sections from the schizophrenic subjects. We conclude that the binding of [3H]raclopride is dependent on methodology and therefore data from in vitro and in vivo studies using this drug should be interpreted with caution.