In vitro characterization of agonist, antagonist, inverse agonist and agonist/antagonist benzodiazepines.

The efficacy of coupling between the benzodiazepine receptor and chloride channel as well as the coupling to the GABA receptor is differentially affected by different benzodiazepine ligands. In general, the order of efficacy with regard to allosteric effects of benzodiazepine ligands on the chloride channel ([35S]TBPS) and GABA receptor ([3H]muscimol), is: agonist greater than agonist/antagonist greater than partial agonist greater than antagonist; with inverse agonists acting in a manner opposite to the classical benzodiazepine agonists. The chloride ionophore is allosterically modulated both by benzodiazepine and GABA receptors.