Activated Microglia in the Early Stage of a Rat Model of Parkinson's Disease: Revealed by PET-MRI Imaging by [ 18 F]DPA-714 Targeting TSPO.

In the past decades, translocator protein (TSPO) has been considered as an in vivo biomarker to measure the presence of neuroinflammatory reactions. In this study, expression of TSPO was quantified via [ 18 F]DPA-714 positron emission tomography-magnetic resonance imaging (PET-MRI) imaging to investigate the effects of microglial activation associated with motor behavioral impairments in the 6-hydroxydopamine (6-OHDA)-treated rodent model of Parkinson's disease (PD). [ 18 F]FDG PET-MRI (for non-specific inflammation), [ 18 F]D 6 -FP-(+)-DTBZ PET-MRI (for damaged dopaminergic neurons), post-PET immunofluorescence, and Pearson's correlation analyses were also performed. The time course of the striatal [ 18 F]DPA-714 binding ratio elevated in 6-OHDA-treated rats during 1-3 weeks post-treatment, with the peak TSPO binding in the 1st week. No differences between bilateral striatum in [ 18 F]FDG PET imaging were found. Moreover, an obvious correlation between [ 18 F]DPA-714 SUV R R / L and rotation numbers was found ( r = 0.434, * p = 0.049). No correlation between [ 18 F]FDG SUV R R / L and rotation behavior was found. [ 18 F]DPA-714 appeared to be a potential PET tracer for imaging the microglia-mediated neuroinflammation in the early stage of PD.