Decreased density of serotonin 2A receptors in the superior temporal gyrus in schizophrenia-a postmortem study

The superior temporal gyrus (STG) is strongly implicated in the pathophysiology of schizophrenia, particularly with regards to auditory hallucinations. In this study, using in situ quantitative autoradiography in postmortem tissue, we investigated the binding of the ³H]ketanserin to 5-HT_2A receptors and ³H]mesulergine to 5-HT_2C receptors in the left STG of 8 male schizophrenic patients compared to 8 control subjects. A strong ³H]ketanserin binding was observed in the STG, however there was a very weak ³H]mesulergine binding in the STG. A significant decrease in binding of ³H]ketanserin was clearly observed in schizophrenia patients in comparison with control subjects. There were no significant correlations between 5-HT_2A binding density and age, postmortem intervals, or brain pH. These results suggest that the alterations of the 5-HT_2A receptors contribute to the pathophysiology of the STG in schizophrenia. Furthermore, there is a clear tendency for a positive correlation between 5-HT_2A and muscarinic M1 receptor bindings, and for negative correlations between 5-HT_2A and GABA_A receptor bindings and between muscarinic M1 and GABA_A receptor bindings. This provides a possible mechanism of auditory hallucinations through interactions between 5-HT_2A, acetylcholine muscarinic and GABA transmissions in the STG in schizophrenia.