The vesamicol analogue, meta-[125I]iodobenzyltrozamicol [(+)-[125I]MIBT] was evaluated as a probe for the in vitro labeling of the vesicular acetylcholine transporter in primate brain. In the striatum, (+)-[125I]MIBT bound a single high-affinity site with a K(d) value of 4.4 ± 0.7 nM. Competition for (+)-[125I]MIBT binding to the striatum by a group of vesamicol analogues displayed a pharmacological profile similar to the rank order of potency previously observed for the vesicular acetylcholine transporter on Torpedo synaptic vesicles. High-affinity binding of(+)-[125I]MIBT in the occipital cortex was characterized by a K(d) value of 4.6 ± 1.1 nM. However, the rank order of potency for inhibition of(+)-[125I]MIBT binding to the occipital cortex by the same test compounds differed from that observed in the striatum. The results suggest that(+)-[125I]MIBT is a reliable probe of the vesicular acetylcholine transporter in primate striatum, but its binding in primate occipital cortex is more complex.
- Acetylcholine transporter
- Synaptic vesicle
- Vesamicol receptor
ASJC Scopus subject areas
- Cellular and Molecular Neuroscience