Non-specificity of "behavioral despair" as an animal model of depression.

When mice are forced to swim in a restricted space, they will cease attempts to escape and adopt a characteristic immobile posture which can be readily identified and timed. Imipramine decreased the duration of immobility in a 4 min swimming test in a dose-related manner. Likewise, caffeine, triiodothyronine and pentobarbital reduced immobility. These latter findings shed doubt upon the specificity of the behavioral despair swimming test to identify substances with antidepressant activity.