Function of sigma1 receptors in Parkinson's disease

Objective - The objective of this study was to investigate the mapping of sigma 1 receptors in Parkinson's disease (PD) using [ 11 C]SA4503 and positron emission tomography (PET), and to assess whether sigma 1 receptors are involved in the damaged dopaminergic system in PD patients. Materials and methods - We studied seven normal volunteers and six PD patients. The low density of dopamine transporters and the normal or high density of dopamine receptors were confirmed in the putamen of all patients using [ 11 C]CFT and [ 11 C]RAC PET. A dynamic series of PET data acquisition was performed with arterial blood sampling. We computed the binding potential (BP) of [ 11 C]SA4503. Results - In PD patients, the BP was significantly lower on the more affected than the less affected side of the anterior putamen, although there was no significant difference with respect to the BP between patients and controls. Conclusions - Release of dopamine is reduced asymmetrically in the putamen of early PD. [ 11 C]SA4503 PET is an indicator of presynaptic dopaminergic damage in PD.