Autoradiographic distribution of [³H]‐suriclone binding sites in the rat brain

Abstract

Suriclone is a potent non-benzodiazepine anxiolytic belonging to the cyclopyrrolone family. This study examines the distribution and properties of [ Unlike benzodiazepine (BZ) agonists, [3H1-suriclone binding to rat brain sections was not increased in the presence of GABA, and unlike imidazopyridines such as alpidem, suriclone was unable to discriminate between the BZ, and BZ, phenotype of the GABA, receptor. The autoradiographic distribution of [3H]-suriclone binding sites in the rat brain was heterogeneous and relatively similar to that previously described for GABA, receptors labelled by benzodiazepines; some regions, however, such as certain cortical areas, displayed a different labelling.The highest densities were found in frontal, occipital, parietal, and cingulate cortices (layers I, II, Ill, IV), in the molecular layer of the cerebellum, in the superior colliculus and in the hippocampus. Moderate binding densities appeared in numerous areas such as the inferior colliculus, the central grey, the dorsal raphe, and the hypothalamus whereas caudate putamen, globus pallidus, and thalamic nuclei displayed a low density of [3H]-suriclone binding sites.(0 1995 Wiley-Liss, Inc.

The mechanism of action of zopiclone

“…It can be seen that there is a good correlation between efficacy and TBPS shift for all ligands, including cyclopyrrolones (indicated by the open columns). that only GABAA receptors are labelled by this radioligand (Malgouris et al, 1995).…”

“…Zopiclone does not appear to distinguish between BZi and BZ2 phenotypes (fig 7;Blanchard etal, 1983;Doble eral, 1992) and only has low affinity for the BZq phenotype (Wong et al, 1995). Moreover, [3H]-suriclone appears to bind with uniform affinity to GABAA receptors throughout the brain (Malgouris et al, 1995), with the exception of the ~-containing receptors in the molecular layer of the cerebellum (BIA). A detailed study of the affinity of zopiclone or other cyclopyrrolones for recombinant GABAA receptors containing identified subunits remains, however, to be performed.…”