Binding of 125I-iodovinyltetrabenazine to CNS vesicular monoamine transport sites.

Binding characteristics of a novel radioiodinated tetrabenazine (TBZ) analog (iodovinyltetrabenazine; 125I-TBZ-Fraction I) were evaluated. In rat striatal homogenates, 125I-TBZ-I displayed a pharmacological profile consistent with specific binding to vesicular monoamine transport (VMAT) sites. In vitro autoradiographic studies using rat brain sections further demonstrated that 125I-TBZ-I labeled the regions rich in VMAT sites, and it may be a useful marker for these sites. This novel radioiodinated ligand, with high specific activity and high binding affinity, may provide a powerful tool for the in vitro assessment of neuronal loss in various neurodegenerative diseases.