Commentary on the mode of action of benzodiazepines.

Evidence is presented showing that the benzodiazepines produce their variety of pharmacological effects by activating GABA A receptors in the mammalian brain. Different classes of benzodiazepine receptor ligands have been developed which can cause or alleviate anxiety according to the nature of their interaction with the GABA A receptor. There is now evidence that natural ligands also exist in the brain which can modulate GABA A receptor function. The changes in the responsiveness of the GABA A receptor to chronic benzodiazepine treatment is discussed with reference to the phenomenon of tolerance dependence and withdrawal.