title: Evidence for the presence of benzodiazepine receptor subclasses in different areas of the human brain.
abstract: The kinetic characteristics of [3H]flunitrazepam ([3H]FNT) and [3H]ethyl-beta-carboline-3-carboxylate ([3H]beta-CCE) were compared in three different areas of the human brain. As revealed by the Scatchard plot analysis the total number of binding sites labelled by [3H]beta-CCE was markedly lower than that labelled by [3H]FNT. In fact, only 50% of the binding sites for [3H]FNT were also available for [3H]beta-CCE. This finding indicates that in the cerebral cortex, hippocampus and cerebellum of the human brain at least 50% of the benzodiazepine recognition sites are that of Type II. This conclusion is further supported by the evidence that CL-218872 (5 X 10(-6) M), a specific ligand for Type I benzodiazepine recognition site, inhibited [3H]FNT binding by 50% in membranes from the above brain areas. The results suggest that two distinct types of benzodiazepines recognition sites are present in different areas of the human brain.
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000378:metabolism; D001923:Brain Chemistry; D002243:Carbolines / Q000378:metabolism; D002531:Cerebellum / Q000032:analysis; D002540:Cerebral Cortex / Q000032:analysis; D005260:Female; D005445:Flunitrazepam / Q000378:metabolism; D006624:Hippocampus / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D011869:Radioligand Assay; D011963:Receptors, GABA-A / Q000032:analysis* / Q000378:metabolism
chemical_list: D002243:Carbolines; D011963:Receptors, GABA-A; D005445:Flunitrazepam; C024915:beta-carboline-3-carboxylic acid ethyl ester