Antidepressant and anxiolytic effects of alprazolam versus the conventional antidepressant desipramine and the anxiolytic diazepam in the forced swim test in rats.

The antidepressant and anxiolytic effects of alprazolam were compared to those of desipramine, diazepam and buspirone in the forced swim test. Subchronic alprazolam induced a reduction in immobility similar to that of desipramine in 'non-pretested' and 'pretested' rats. In 'non-pretested' rats, the anti-immobility effect of desipramine was potentiated by diazepam and alprazolam, given before subchronic desipramine, while the anti-immobility effect of subchronic alprazolam was counteracted by diazepam. Diazepam, administered before the pretest session, counteracted, 24 h later, the anti-immobility effect of subchronic desipramine and alprazolam; alprazolam counteracted the anti-immobility effect of alprazolam but not of desipramine, buspirone at the highest doses tested potentiated the anti-immobility effect of subchronic desipramine but not of alprazolam. These data provide further support for the hypothesis that the GABA/benzodiazepine/Cl complex is directly implicated in the action of antidepressants and that systems other than the GABA system are involved in the antidepressant and anxiolytic effects of alprazolam.