The effects of triazolobenzodiazepines in two animal tests of anxiety and in the holeboard.

In addition to possessing anti-anxiety activity in man, triazolobenzodiazepines have been reported to have antidepressant and antipanic properties. In this they differ from classical 1,4-benzodiazepines that have only anti-anxiety activity. The purpose of the present study was to examine the effects of the triazolobenzodiazepines in two animal tests of anxiety and in the holeboard, to see whether clear differences could be observed between them and the 1,4-benzodiazepines. After acute administration, U-43,465 (16 mg kg-1) had a significant anxiolytic effect in the social interaction test. Neither adinazolam (1-3.5 mg kg-1) nor alprazolam (0.125-2 mg kg-1) had a significant effect. It is suggested that this is because, with adinazolam and alprazolam, doses at which anxiolytic effects can be observed are close to those at which sedative effects can be observed. U-43,465 (8-16 mg kg-1) and alprazolam (1-2 mg kg-1) had significant anxiolytic effects in the elevated plus-maze test of anxiety. U-43,465 (8-32 mg kg-1), adinazolam (0.5-5 mg kg-1) and alprazolam (0.2-2.0 mg kg-1) caused dose-related reductions in exploratory head-dipping, locomotor activity and rearing in the holeboard. In general the results seen in the three tests with the triazolobenzodiazepines alprazolam and adinazolam were similar to those seen with classical 1,4-benzodiazepines. With U-43,465, however, an anxiolytic effect was observed in the social interaction test after acute treatment; chronic treatment is required to see an effect with classical 1,4-benzodiazepines. In this U-43,465 resembles the effects of several novel non-benzodiazepine putative anxiolytic compounds that are believed to have less sedative potential than the benzodiazepines.