In vivo labeling of nicotinic acetylcholine receptors in brain with [3H]epibatidine.

In vivo imaging of nicotinic acetylcholine receptors in brain has been hampered by lack of an adequate radioligand. In the present study, [3H]epibatidine was administered to mice intravenously, and its time-course in brain regions and sensitivity to blockade by nicotinic drugs were studied. The distribution of radioligand accumulation in brain, and the pharmacological characteristics of binding indicate that radiolabeled forms of epibatidine would be exceptionally promising ligands for the study of nicotinic acetylcholine receptors in vivo.