CONDITIONED SUPPRESSION AND THE EFFECTS OF PENTOBARBITAL WITH PICROTOXIN, FLUMAZENIL, AND R05-3663

In two experiments, rats trained to lever press for food were maintain ed under a conditioned suppression procedure and then given an acute r egime of drug administration involving pentobarbital (10 mg/kg). In bo th experiments, pentobarbital reduced conditioned suppression. In the first experiment (4 rats), this effect was increased by the combinatio n of the specific benzodiazepine antagonist flumazenil (10 mg/kg) with pentobarbital but unaffected by the combination of picrotoxin (1.5 mg /kg) with pentobarbital. In the second experiment (3 rats), this effec t was attenuated when picrotoxin (2.0 mg/kg) or Ro5-3663 (5.0 mg/kg) w ere also administered. These findings add to the data on the effects o f anxiolytics and related compounds on conditioned suppression, they p rovide more information on the possible nature of the GABA/benzodiazep ine receptor complex and suggest that flumazenil can have anxiolytic a s well as anxiogenic effects.