The superior temporal gyrus (STG) is strongly implicated in the pathophysiology of schizophrenia, particularly with regards to auditory hallucinations. Purpose: The objective of this study was to investigate the relationships of pathological changes in 5-HT2A, muscarinic M1 and GABAA receptors in the STG of schizophrenia. Methods: Using in situ quantitative autoradiography, the bindings of 5-HT2A, muscarinic M1 and GABAA receptors in the STG were examined. Results: Significant decreases in binding density of 5-HT2A and M1 receptors were observed in schizophrenia patients in comparison with control subjects (n=8; p<0.05). However there was an increased density of GABAA receptor in the STG of schizophrenia (p<0.05). A clear positive correlation between 5-HT2A and muscarinic M1 receptor bindings (r=0.44, p=0.087) and negative correlations between muscarinic M1 and GABAA receptor
bindings (r=-0.49, p=0.057) have been revealed. Conclusions: These results suggest that the related pathological alterations of the 5-HT2A, muscarinic M1 and GABAA receptors contribute to pathophysiology of the STG in schizophrenia. There is a possible mechanism of auditory hallucinations through interactions between 5-HT2A, muscarinic and GABA transmissions in the STG in schizophrenia.