Background: Previous studies have reported that the 38-kd synaptic vesicle-associated protein, synaptophysin, is decreased in the prefrontal cortex of subjects with schizophrenia.
Methods: To determine whether the decreased protein levels reflect diminished expression of the synaptophysin gene by prefrontal cortex neurons, we used in situ hybridization histochemistry to determine the cellular levels of synaptophysin messenger RNA in prefrontal cortex area 9 from 10 matched pairs of schizophrenic and normal control subjects.
Results: Neither the density of neurons with detectable levels of synaptophysin messenger RNA nor the mean level of synaptophysin messenger RNA expression per neuron differed between schizophrenic and control subjects in any cortical layer.
Conclusions: These findings indicate that the expression of synaptophysin messenger RNA is not altered in this brain region in schizophrenia. Consequently, reduced levels of synaptophysin protein in the prefrontal cortex of subjects with schizophrenia are more likely to reflect either posttranscriptional abnormalities of synaptophysin in prefrontal cortex neurons or a diminished number of axonal projections to the prefrontal cortex from other brain regions.