In vivo imaging of adenovirus-mediated over-expression of dopamine D2 receptors in rat striatum by positron emission tomography.

PET was used to provide in vivo imaging of the over-expression of dopamine D2 receptor (D2R) induced by adenovirus vector-mediated gene transfer in rat striatum. The uptake of three kinds of D2R-specific ligands, [11C]raclopride, [11C]nemonapride and [11C]N-methylspiperone, measured by PET was higher in the striatum injected with the vectors for D2R than the contralateral striatum injected with a control vector 2-3 days after injection. However, the uptake of [11C]SCH 23390, a dopamine D1 receptor specific ligand, or [11C]beta-CIT-FP, a dopamine transporter specific tracer, was not different between bilateral striata. Co-injection of excess unlabeled raclopride inhibited the uptake of [11C]raclopride. At day 16 the increased uptake of [11C]raclopride declined to basal level, consistent with past in vitro assessment of this vector. In vivo imaging of D2R will permit longitudinal assessment of the efficiency of this and similar vectors in rat brain that can be related to functional changes being observed.