INVIVO STUDIES OF [I-125] IODOBENZAMIDE AND [C-11] IODOBENZAMIDE - A LIGAND SUITABLE FOR POSITRON EMISSION TOMOGRAPHY AND SINGLE PHOTON-EMISSION TOMOGRAPHY IMAGING OF CEREBRAL D(2)-DOPAMINE RECEPTORS

Iodobenzamide (IMB) labeled with either [C-11] or [I-125] was studied in mice and baboons. Pharmacological studies demonstrated an in vivo binding profile compatible with D2 dopamine receptors. Mouse biodistribution studies with both [C-11]IMB and [I-125]IMB showed a similar brain distribution of radioactivity. Mouse [I-125]IMB studies with amphetamine and reserpine pretreatment suggested that IMB may be less susceptible to endogenous dopamine competition for D2 receptor binding in vivo as compared to raclopride. Preliminary baboon studies showed haloperidol competition for IMB binding sites.