Altered response to benzodiazepine anxiolytics in mice lacking GABA B(1) receptors.

Recently, we demonstrated that mice lacking the GABA(B(1)) subunit were more anxious than wild-type animals in several behavioural paradigms, most notably in the light-dark test. In an attempt to assess the effects of classical benzodiazepine anxiolytics on anxiety-like behaviour observed in these mice, animals were administered either chlordiazepoxide (10 mg/kg, p.o.) or diazepam (7.5 mg/kg, p.o.) prior to testing in the light-dark box. Surprisingly, in contrast with the wild-type mice, neither benzodiazepines decreased anxiety-like behaviour in GABA(B(1))(-/-) mice. These data suggest that targeted deletion of GABA(B(1)) subunit alters GABA(A) receptor function in vivo.