GABA membrane steroid receptors

Figure 4.1 Benzodiazepines interact with the GABA receptor in the brain and activate the ceii membrane of neurons to open and allow negative chioride ions (Cl ) to enter the neuron (a, ), y subunits form the Cl- ion). This entry inhibits that neuron s ability to fire an action potential. The GABA receptor also has binding sites for other substances, such as steroids, barbiturates, and alcohol.

It should be noted that in addition to the GABA(A)-R benzodiazepine-binding sites or central benzodiazepine Rs (CBZ-Rs) there are peripheral benzodiazepine Rs (PBZ-Rs) associated with the outer membrane of mitochondria in glial cells and cells of peripheral tissue and which are involved in cholesterol transport and hence in regulation of steroid hormone synthesis. The GABA(B)-Rs are metabotropic and coupled via heterotrimeric G proteins to Ca2+ and K+ channels (Chapter 5). The psychotropic GABA breakdown product y-hydroxybutyrate (GHB) also acts via heterodimeric G protein-linked receptors (see Chapter 5). 

---