GABA enhancement of flunitrazepam binding in mice selectively bred for differential sensitivity to ethanol.

The binding of the benzodiazepine [3H]flunitrazepam (FNZ) and the allosteric enhancement of FNZ binding by gamma-aminobutyric acid (GABA) were investigated in brain tissue from short-sleep (SS) and long-sleep (LS) mice, lines selectively bred for differential sensitivity to ethanol. GABA enhanced FNZ binding in a dose-dependent manner in both lines. This enhancement was greater in SS than in LS cortical and cerebellar regions, but did not differ between lines in midbrain or hindbrain regions. In whole brain, no difference was observed between the two lines in the number or affinity of benzodiazepine receptors, as determined by FNZ binding. These results suggest that the nature of allosteric interactions within the GABA-benzodiazepine receptor complex is different for LS and SS mice.