Visualization by positron emission tomography of the apparent regional heterogeneity of central type benzodiazepine receptors in the brain of living baboons.
The feasibility of visualizing the heterogeneity of benzodiazepine (BDZ) receptors in the brain of living baboons was investigated using Positron Emission Tomography. Ethyl 8-fluoro-5,6-dihydro-5-methyl 6-oxo-4H-imidazo (1,5-a) (1, 4) benzodiazepine-3-carboxylate (RO 15 1788) labelled by carbon 11 (11C-RO 15 1788) was I.V. injected for the "in vivo" labelling of the central type BDZ receptors. Displacement experiments were performed 20 minutes after the administration of the radioligand by two different cold drugs: RO 15 1788 which has an equal affinity for central type BDZ receptors, and propyl B-Carboline-3-carboxylate (B-CCP) which favours the sites located in the cerebellum. Different sensitivities to these two drugs displacement of 11C-RO 15 1788 binding "in vivo" were observed: on the one hand in the regional localization of the displacement, and on the other hand, in the amount of the radioactivity displaced. The apparent interregional heterogeneity of the displacement seen in the cerebellum and in the temporal cortex are discussed in terms of discrepancies observed "in vitro" at physiological temperature, between cerebellar and non-cerebellar BDZ central type binding sites.
Mazière
M
M
Hantraye
P
P
Kaijima
M
M
Dodd
R
R
Guibert
B
B
Prenant
C
C
Sastre
J
J
Crouzel
M
M
Comar
D
D
Naquet
R
R
D000818:Animals; D001570:Benzodiazepinones; D001667:Binding, Competitive; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D002243:Carbolines; D002250:Carbon Radioisotopes; D002531:Cerebellum / Q000000981:diagnostic imaging / Q000378:metabolism; D005442:Flumazenil; D006651:Histocytochemistry; D008297:Male; D010215:Papio; D011869:Radioligand Assay; D011963:Receptors, GABA-A / Q000032:analysis*; D014055:Tomography, Emission-Computed
D001570:Benzodiazepinones; D002243:Carbolines; D002250:Carbon Radioisotopes; D011963:Receptors, GABA-A; D005442:Flumazenil; C028585:propyl beta-carboline-3-carboxylate