Intrinsic actions of benzodiazepine antagonists.

RO 15-1788 (4-20 mg/kg), both alone and in combination with chlordiazepoxide (5 mg/kg), increased exploratory head-dipping in an holeboard above control levels. This intrinsic action of a benzodiazepine antagonist is not reversed, and is even augmented, by chlordiazepoxide. RO 15-1788 alone had no effect on locomotor activity, but antagonized the sedative effects of chlordiazepoxide. beta-CCE (1 and 2 mg/kg) was without effect on locomotor activity, but the higher dose reduced head-dipping.