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 transporte rs in the living primate brain is described, using [C-11]tetrabenazine ([C-11]TBZ) and Positron Emission Tomography (PET). Radioligand uptak e into brain is rapid, and at short time periods (10-30 minutes) the h igher uptake and retention of the radiotracer in the more densely dopa minergic innervated striatum is clearly visualized. Specific binding i n striatum can be entirely blocked with co-administration of a pharmac ological dose (1 mg/kg i.v.) of tetrabenazine. In a unilaterally MPTP- lesioned monkey, specific binding of radioligand was absent in the, st riatum on the lesioned side, with no effect on radiotracer distributio n in the cortex, cerebellum or contralateral striatum. PET imaging wit h [C-11]TBZ provides a new approach to the in vivo study of monoaminer gic neurons and their loss in neurodegenerative diseases.