Category: Parkinson's Disease: Neuroimaging
Objective: To investigate glutamatergic signaling in Parkinson’s disease (PD) compared to age- and gender-matched healthy controls by using 11C-ABP688-PET combined with MRI.
Background: Increasing evidence suggests that, upon dopaminergic depletion of the basal-ganglia motor network, multiple neurotransmitter systems get affected in Parkinson’s disease. Specifically, there seems to be an overactivity of the glutamatergic system, and anti-glutamatergic drugs are used in clinical routine. However, detailed knowledge of the significance of mGluR5 in PD is lacking.
Method: 8 PD patients without dyskinesias and 8 age- and gender-matched healthy controls (HC) underwent 11C-ABP688-PET to measure availability of mGluR5 in the motor system. Metabolite corrected volumes of distribution (Vt) were determined during steady-state condition of a bolus-infusion protocol. T1-weighted images were acquired for volume of interest (VOI) analysis and FLAIR images to rule out vascular parkinsonism. None of the participants was taking any glutamatergic medication and all participants were non-smokers.
Results: Mixed-model analysis of variance with the between-subject factor group (HC vs. PD) and the within-subject factor region (VOIs: caudate, putamen, pallidum, postcentral gyrus) revealed significant main effects for the factors group (F(1,14) = 5.33; p < 0.05) and region (F(3,42) = 186.56; p < 0.001) due to higher mGluR5 availability in PD patients (HC vs. PD, mean ± standard deviation; caudate: 2.9 ± 0.5 vs. 3.6 ± 0.7, putamen: 3.3 ± 0.5 vs. 4.2 ± 0.9, pallidum: 2.4 ± 0.4 vs. 3.0 ± 0.7, postcentral gyrus: 2.7 ± 0.4 vs. 3.4 ± 0.8) [figure1].
Conclusion: PD patients show a higher availability of the mGluR5 in key regions of the motor system. This supports the notion of a glutamatergic dysregulation in PD. Further investigation is needed to determine whether mGluR5 availability differs in specific subgroups of PD patients, e.g. patients with sleep-wake disturbances and dyskinesias.
To cite this abstract in AMA style:
C.J Doppler, E. Farrher, C. Régio Brambilla, C.P Filss, J. Lindemeyer, A. Gogishvili, B. Neumaier, M.T Barbe, I. Neuner, C. Lerche, N.J Shah, K.J Langen, G.R Fink, M. Sommerauer. Increased availability of the metabotropic glutamate receptor 5 in the motor system of patients with Parkinson’s disease [abstract]. Mov Disord. 2020; 35 (suppl 1). https://www.mdsabstracts.org/abstract/increased-availability-of-the-metabotropic-glutamate-receptor-5-in-the-motor-system-of-patients-with-parkinsons-disease/. Accessed June 15, 2025.« Back to MDS Virtual Congress 2020
MDS Abstracts - https://www.mdsabstracts.org/abstract/increased-availability-of-the-metabotropic-glutamate-receptor-5-in-the-motor-system-of-patients-with-parkinsons-disease/