Objective: To evaluate expression of brain metabotropic glutamatergic receptor 5 and the relationship with clinical measures in Parkinson’s disease patients.

Background: Metabotropic glutamate receptor 5 (mGluR5)-mediated signalling has been reported to be altered in animal models of Parkinson’s disease. The in-vivo mGluR5 expression was also shown to be altered in animal models of PD by PET studies using 11C-ABP688. However, studies in PD patients have yet been reported.

Methods: Twelve drug-naïve and thirteen treated PD patients, and eleven normal controls underwent 11C-ABP688 PET/MR imaging, and regional bindings in subcortical and cortical areas were evaluated. 18F-FP-CIT PET scans for both patient groups were acquired, and putaminal bindings were examined for associations between dopaminergic loss and 11C-ABP688 binding changes.

Results: 11C-ABP688 bindings in motor-related cortical regions increased in PD treated group compared with normal controls in both hemispheres. The ABP688 distribution volumes ratios in these regions postively correlated with motor severity in both PD groups measured by Hoehn and Yar stage and motor UPDS scores. Subcortical 11C-ABP688 bindings were indifferent between PD patients and controls. Putaminal 18F-FP-CIT uptakes correlated with caudate 11C-ABP688 binding in more affected hemisphere, but did not associate with changes in cortical bindings in both more and less affected hemispheres.

Conclusions: The mGluR5 seems to be upregulated in motor-related cortical regions in PD patients, which is correlated with severity of PD. Our study supports the role of mGluR5 in the pathogenesis of PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/alterations-of-cortical-metabotropic-glutamate-receptor-mediated-signaling-in-patients-with-parkinsons-disease/