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Initial evaluation of123I-5-I-R91150, a selective 5-HT2A ligand for single-photon emission tomography, in healthy human subjects

1997; Springer Science+Business Media; Volume: 24; Issue: 6 Linguagem: Inglês

10.1007/bf00841413

1432-105X

Geraldo F. Busatto, Lyn S. Pilowsky, Durval C. Costa, John Mertens, Dirk Terrierel, Peter J. Ell, Rachel S. Mulligan, Michael J. Travis, J. E. Leysen, Dominic Lui, Sveto Gacinovic, Wendy A. Waddington, Anne Lingford‐Hughes, Robert Kerwin,

Anesthesia and Sedative Agents

The mapping of 5-HT2 receptors in the brain using functional imaging techniques has been limited by a relative lack of selective radioligands. Iodine-123 labelled 4-amino-N-[1-[3-(4-fluorophenoxy)propyl]-4-methyl-4-piperidinyl]-5-iodo-2-methoxybenzamide (123I-5-I-R91150 or123I-R93274) is a new ligand for single-photon emission tomography (SPET), with high affinity and selectivity for 5-HT2A receptors. This study reports on preliminary123I-5-I-R91150 SPET, wholebody and blood distribution findings in five healthy human volunteers. Maximal brain uptake was approximately 2% of total body counts at 180 min post injection (p.i.). Dynamic SPET sequences were acquired with the brain-dedicated, single-slice multi-detector system SEM-810 over 200 min p.i. Early peak uptake (at 5 min p.i.) was seen in the cerebellum, a region free from 5HT2A receptors. In contrast, radioligand binding in the frontal cortex increased steadily over time, up to a peak at approximately 100–120 min p.i. Frontal cortex-cerebellum activity ratios reached values of 1.4, and remained stable from approximately 100 min p.i. onwards. Multi-slice SPET sequences showed a pattern of regional variation of binding compatible with the autoradiographic data on the distribution of 5-HT2A receptors in (cerebral cortex>striatum>cerebellum). These findings suggest that123I-5-I-R91150 may be used for the imaging of 5-HT2A receptors in the living human brain with SPET.