INVIVO IMAGING OF MONOAMINERGIC NERVE-TERMINALS IN NORMAL AND MPTP-LESIONED PRIMATE BRAIN USING POSITRON EMISSION TOMOGRAPHY (PET) AND [C-11] TETRABENAZINE

The first successful in vivo imaging of monoamine vesicular transporters in the living primate brain is described, using [C-11]tetrabenazine ([C-11]TBZ) and Positron Emission Tomography (PET). Radioligand uptake into brain is rapid, and at short time periods (10-30 minutes) the higher uptake and retention of the radiotracer in the more densely dopaminergic innervated striatum is clearly visualized. Specific binding in striatum can be entirely blocked with co-administration of a pharmacological dose (1 mg/kg i.v.) of tetrabenazine. In a unilaterally MPTP-lesioned monkey, specific binding of radioligand was absent in the, striatum on the lesioned side, with no effect on radiotracer distribution in the cortex, cerebellum or contralateral striatum. PET imaging with [C-11]TBZ provides a new approach to the in vivo study of monoaminergic neurons and their loss in neurodegenerative diseases.