Radiosynthesis, Cerebral Distribution, and Binding of -1-(p-Iodophenyl)-3-(1-adamantyl)guanidine, a Ligand for ? Binding Sites

Article abstract of DOI:10.1021/jm00103a005

An analog of 1,3-di-o-tolylguanidine (DTG), <125I>-labeled 1-(p-iodophenyl)-3-(1-adamantyl)guanidine (PIPAG), was synthesized as a potential ligand for cerebral ? binding sites.Data from in vitro binding experiments and in vivo experiments on brain distribution suggested that PIPAG binds to ? binding sites with high affinity (K_d in low nanomolar range) as determined by Scatchard analysis and relative potencies of ?-specific drugs.Haloperidol had the highest potency to inhibit <125I>PIPAG binding.It was followed by DTG, BMY 14802, and (+)-N-allylnormetazocine.Compounds with high affinities for dopamine receptors (but low affinity for ? binding sites), for opioid receptors, for nicotinic acetylcholine receptors, and for phencyclidine receptors were ineffective inhibitors of <125I>PIPAG binding.