RADIOTRACERS FOR IMAGING CANNABINOID SUB-TYPE1 (CB1) RECEPTOR

摘要

Imaging of cannabinoid subtype-1 (CB1) receptors in vivo is important for understanding their role in neuropsychiatric disorders and for drug development. Radioligands for imaging with PET or SPECT are required for this purpose. The present invention provides new ligands, including (-)-3-(4-chlorophenyl)-N'-[(4-cyanophenyl)sulfonyl]-4-phenyl-4,5-dihydro-1H-pyrazole-1-carboxamidine) and 1-(2-iodophenyl)-4-cyano-5-(4-methoxyphenyl)-N-(piperidin-1-yl)-1H-pyrazole-3-carboxylate, which were found to have high affinity and selectivity for binding to CB1 receptors. These compounds were labeled and evaluated as a PET and SPECT radioligands for use in mammals. After injection of [11C] (-)-3-(4-chlorophenyl)-N'-[(4-cyanophenyl)sulfonyl]-4-phenyl-4,5-dihydro-1H-pyrazole-1-carboxamidine) into mammals, high uptake and retention of radioactivity across brain according to the rank order of CB1 receptor densities was observed. Likewise 125I-labeled 1-(2-iodophenyl)-4-cyano-5-(4-methoxyphenyl)-N-(piperidin-1-yl)-1H-pyrazole-3-carboxylate showed a distinct regional distribution of radioactivity in brain tissue according to the known CB1 receptor densities. Ligands of the present invention are useful for in vivo imaging CB1 receptor function in mammals.