Benzodiazepine receptor multiplicity.

Receptors for gamma-aminobutyric acid (GABA) are phylogenetically old and extensive GABA receptor multiplicity had already evolved in invertebrate species. High affinity, "brain specific", benzodiazepine (BZ) receptors, present in the central nervous systems of virtually all vertebrate species, represent a heterogeneous sub-class of GABA receptors. Functional GABA-BZ-ion receptor complexes are aggregates consisting of different kinds of sub-units which are probably coded for by separate genes. These sub-units may be combined in different ways to yield different benzodiazepine receptor complexes. Different GABA-BZ-ion receptor complexes probably subserve different physiological functions and more selective drugs modifying these functions will probably be found.