Pharmacology of the benzodiazepine receptor.

The benzodiazepine receptor (BZR) is an intrinsic allosteric modulatory site of the GABAA-receptor-chloride channel complex of neuronal membranes mediating the main action of the major inhibitory neurotransmitter GABA. The BZR is unique in recognizing three classes of ligands, two of them producing opposite modulatory effects on the GABAA receptor function in an allosteric fashion (agonists and inverse agonists) and the third acting as antagonists of the two others. Agonists and partial agonists of the BZR (belonging to various chemical classes) have therapeutic applications as broad-spectrum tranquilizers and specific anxiolytics- anticonvulsants, respectively. The BZR antagonist flumazenil, recently introduced in therapy, increases the versatility of agonists in therapy and greatly simplifies the treatment of agonist overdosing. Inverse agonists are interesting probes to analyse the biological basis of anxiety-related emotional disorders.