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 lightâ€"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 lightâ€"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.