Age-related changes of the [11C]CFT binding to the striatal dopamine transporters in the Fischer 344 rats: a PET study.

We investigated the age-related changes of the binding of [11C]CFT to striatal dopamine transporters (DATs) in vivo in Fischer 344 rats by positron emission tomography (PET). The tissue dissection method represented an age-related decrease in the uptake ratio of the striatum to the cerebellum and in the specific binding-to-nonspecific binding ratio of [11C]CFT. PET demonstrated an age-dependent decrease in the striatal uptake of [11C]CFT, however, the kinetic analysis represented the age-related decrease in both the association rate constant (k3) and dissociation rate constant (k4), but not the binding potential (k3/k4) that was a parameter including both of density and affinity of the binding sites. The PET finding was not necessarily coincident with the result investigated in vitro previously. Therefore, careful interpretation is necessary for PET studies using [11C]CFT and small animals such as rats.