GABAA receptor subtypes: any clues to the mechanism of benzodiazepine dependence?

Chronic use of benzodiazepines for the treatment of anxiety has revealed that these drugs can lead to dependence as indicated by withdrawal symptoms following cessation and tolerance to the drugs effects. Together with their reinforcing properties, this has led to them being labelled as scheduled drugs. Our new knowledge regarding the molecular structure of the benzodiazepine binding site and the growing ability to differentiate GABA(A) receptor subtypes, either by genetic manipulation or subtype selective compounds, have begun to facilitate our understanding of what underlies the mechanism of benzodiazepine dependence. In addition, the involvement of GABA(A) receptors in this phenomenon is leading to a greater understanding of other drugs such as alcohol and opiates.