Swimming mice: in search of an animal model for human depression

The validity of Porsolt's forced swimming test as a screening method of antidepressants and as an animal model of depression was evaluated in mice by means of four experiments. It was found that antidepressants specifically counteracted immobility during the forced swimming test (experiment 1). Injection of antidepressants over a fixed period also counteracted immobility (experiment 2). Next, two tests were carried out which revealed that the administration of prior inescapable shocks to the mice prolonged the immobility (experiment 3), and that this prolongation could be attributed only to the 'inescapability' of the prior shocks (experiment 4). These experiments suggested a close relationship between immobility and 'learned helplessness'. Finally, from the viewpoint of McKinney and Bunney's criteria, it was concluded that Porsolt's forced swimming test was a valuable model for investigating the human depression.