IMAGING 5-HT1A RECEPTORS WITH POSITRON-EMISSION-TOMOGRAPHY - INITIAL HUMAN STUDIES WITH [C-11] CPC-222

The novel radioligand [C-11]CPC-222 iperazinyl]ethyl]-N-(2-pyridinyl)- 2-bicyclo[2,2,2] octane carboxamide) was evaluated as an in vivo probe of the 5-HT1A receptors using positron emission tomography (PET). Thr ee human volunteers were imaged with PET over a 90 min period followin g intravenous injection of the radioligand. There was a high accumulat ion of the radioligand in brain regions with a high density of 5-HT1A receptors. The peak cortical concentration was 1.0-2.5% of the injecte d dose per litre. The ratio of radioactivity in receptor-rich regions to that of the cerebellum reached a plateau of 2.5-4.0 by 45 min after injection. Analysis of the plasma revealed no detectable amount of th e potential metabolite, radiolabelled WAY-100634. This new radioligand has suitable properties to study the 5-HT1A receptors in man with PET .