[3H]muscimol binding sites increased in autopsied brains of chronic schizophrenics.

[3H]muscimol binding and glutamic acid decarboxylase (GAD) activity in the prefrontal cortex and caudate nucleus of autopsied brains from 19 chronic schizophrenics and 17 control subjects were investigated. In the schizophrenics, saturation analysis with varying concentrations of [3H]muscimol revealed an increase in the number of GABAA receptors, but there was no significant difference in the affinity. In addition, the enhancement of [3H]muscimol binding by diazepam was significantly greater in schizophrenics than in controls. GAD activity did not differ between controls and schizophrenics. The possibility that GABAergic mechanisms might play a role in case of chronic schizophrenia should be given further attention.