EFFECTS OF DIAZEPAM AND DESIPRAMINE IN THE FORCED SWIMMING TEST - INFLUENCE OF PREVIOUS EXPERIENCE WITH THE SITUATION

The effects of desipramine and diazepam on the behavior of rats in the forced swimming test were studied. Desipramine significantly enhanced struggling behavior, the intensity of its effect being greater in rat s previously exposed to the forced swimming test for 1 or 4 days befor e drug administration. The effect of desipramine on immobility was sig nificant only in rats previously exposed to the test. Acute diazepam a dministration did not modify the behavior of rats in the test. Chronic administration (6 days) of two different doses of diazepam did not al ter the behavior of rats in the forced swimming test, but significantl y decreased the defecation rate, suggesting that the drug was effectiv e as an anxiolytic. The present results suggest that the behavior of r ats in the forced swimming test might be related to mood states rather than to fear/anxiety and that efficacy of the test to detect antidepr essant activity might be enhanced by repeated exposure of the rats to the situation.