[Evaluation of benzodiazepine receptor in the cerebral cortex of Parkinson's disease using 123I-iomazenil SPECT].

123I-iomazenil is a partial inverse agonist of central-type benzodiazepine receptors (BZRs). BZR and the gamma-aminobutylic acid(GABA) receptor comprise a receptor complex in the cerebral cortex. Therefore, 123I-iomazenil SPECT will provide indirect information of the GABA receptor. Since the GABA-ergic system has been reported to modulate the dopaminergic system, the impairment of GABA/BZR may affect parkinsonian symptoms. However, there are few reports on Parkinson's disease(PD) regarding the impairment of GABA/BZR in the cerebral cortex. We found a correlation between motor disability and decrease in 123I-iomazenil uptake in the cerebral cortex, suggesting that BZR in the cerebral cortex of patients with PD may be impaired in proportion to the severity of the disease. In addition, the 123I-iomazenil image is, in part, different from the perfusion image. Therefore, 123I-iomazenil SPECT may give an additional information on the pathophysiology of PD.