Application of [125I] (S)-5-iodonicotine, a new radioiodinated ligand, in the assay of nicotinic acetylcholine receptor binding in the brain

Abstract

[125I](S)-5-Iodonicotine was prepared and its application in the assay of nicotinic acetylcholine receptor binding in the brain was studied. [125I](S)-5-Iodonicotine bound to the rat cortical membrane with high affinity (Kd, 15.0 nm). Various nicotinic cholinergic compounds showed competition with [125I](S)-5-iodonicotine for the binding sites in the rats cortical membrane, and the specificity of its binding was correlated well with that of [H3] cytisine (r = 0.98). These findings suggest that [125I](S)-5-iodonicotine binds to the same sites as [H3] cytisine and indicate that [125I](S)-5-iodonicotine can be applied as a brain nicotine receptor binding assay.