Discriminative Stimulus and Anxiolytic-Like Effects of the Novel Compound CL 273,547

CL 273,547 is a novel nonbenzodiazepine with anxiolytic activity, but with a lesser tendency to produce sedative effects. CL 273,547 was established as a discriminative stimulus in rats (Rattus norvegicus). Triazolam and CL 284,846 substituted for CL 273,547 and decreased response rates. Buspirone did not substitute for CL 273,547, whereas pentobarbital substituted in the majority of the rats. Effects on punished responding of pigeons (Columba livia) also were examined as a preclinical evaluation of anxiolytic-like activity. CL 273,547 increased punished responding in pigeons at doses that had little effect on responding that was not punished. The benzodiazepine receptor antagonist flumazenil partially blocked the discriminative stimulus effects of CL 273,547 in rats and the effects of CL 273,547 on punished responding of pigeons. These results suggest that the nonbenzodiazepine CL 273,547 has benzodiazepine-like discriminative stimulus and anxiolytic effects.