Evidence that the beta-carboline, ZK 91296, can reduce anxiety in animals at doses well below those causing sedation.

The effects of ZK 91296, a beta-carboline derivative that potently displaces [3H]benzodiazepines from their CNS binding sites, were examined in two extensively validated animal tests of anxiety and in the holeboard in rats. In the social interaction test of anxiety. ZK 91296 (5 mg/kg) had an anxiolytic effect that was no longer apparent at a higher dose (15 mg/kg). In a test using exploratory activity on an elevated plus-maze as a measure of anxiety, the effects of ZK 91296 (5-15 mg/kg) did not reach significance. In the holeboard. ZK 91296 did not significantly reduce exploratory head-dipping, locomotor activity or rearing until doses of 40 mg/kg. These data suggest that ZK 91296 can reduce anxiety as assessed by animal tests at doses at which it does not induce sedation.