Photoaffinity labelling of the benzodiazepine receptor cannot be used to predict ligand efficacy.
Irreversible attachment of flunitrazepam to brain membranes occurs on exposure to UV light, resulting in a loss of the number of binding sites detected by saturation binding of [3H]flunitrazepam, but not of [3H]ethyl-beta-carboline-3-carboxylate (beta CCE). Changes in the affinity of ligands for the benzodiazepine receptor produced by photoaffinity labelling, as indicated by the relative IC50 values for the displacement of [3H]beta CCE in photoaffinity labelled versus control membranes, appear to be related to their chemical structure rather than to their pharmacological profile.
D000818:Animals; D001667:Binding, Competitive; D002243:Carbolines / Q000378:metabolism; D003975:Diazepam / Q000378:metabolism; D005445:Flunitrazepam / Q000378:metabolism; D008024:Ligands; D008722:Methods; D011720:Pyrazoles / Q000378:metabolism; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011963:Receptors, GABA-A
D002243:Carbolines; D008024:Ligands; D011720:Pyrazoles; D011956:Receptors, Cell Surface; D011963:Receptors, GABA-A; D005445:Flunitrazepam; D003975:Diazepam