In vivo18F-DOPA PET imaging identifies a dopaminergic deficit in a rat model with a G51D α-synuclein mutation

Abstract

AbstractParkinson’s disease (PD) is a neurodegenerative condition with several major hallmarks, including loss ofsubstantia nigraneurons, reduction in striatal dopaminergic function, and formation of α-synuclein-rich Lewy bodies. Mutations inSNCA, encoding for α-synuclein, are a known cause of familial PD, and the G51D mutation causes a particularly aggressive form of the condition. CRISPR/Cas9 technology was used to introduce the G51D mutation into the endogenous ratSNCAgene.SNCAG51D/+andSNCAG51D/G51Drats were born in Mendelian ratios and did not exhibit any severe behavourial defects.L-3,4-dihydroxy-6-18F-fluorophenylalanine (18F-DOPA) positron emission tomography (PET) imaging was used to investigate this novel rat model. Wild-type (WT),SNCAG51D/+andSNCAG51D/G51Drats were characterised over the course of ageing (5, 11, and 16 months old) using18F-DOPA PET imaging and kinetic modelling. We measured the influx rate constant (Ki) and effective distribution volume ratio (EDVR) of18F-DOPA in the striatum relative to the cerebellum in WT,SNCAG51D/+andSNCAG51D/G51Drats. A significant reduction inEDVRwas observed inSNCAG51D/G51Drats at 16 months of age indicative of increased dopamine turnover. Furthermore, we observed a significant asymmetry in EDVR between the left and right striatum in agedSNCAG51D/G51Drats. The increased and asymmetric dopamine turnover observed in the striatum of agedSNCAG51D/G51Drats is similar to prodromal PD, which suggests the presence of compensatory mechanisms.SNCAG51Drats represent a novel genetic model of PD, and kinetic modelling of18F-DOPA PET data has identified a highly relevant early disease phenotype.