Coping with the forced swim stressor: Current state-of-the-art

The forced swim test (FST) for rodents does not model despair or helplessness. It also is not a read-out for depression, anxiety, psychomotor retardation or autism, because these are anthropomorphic interpretations of the rodent's acquired immobility. Rather, the transition from swimming to immobility allows to examine the mechanistic underpinning of coping with inescapable stressors. However, in a recent detailed analysis of the FST application over the past 40 years, we noted a dramatic surge in the use of this test to phenotype animals as 'depressed'. As a follow up to that report, we now present an analysis of the use of the FST over the past three years. This literature analysis shows that the popularity of the FST is still increasing and that the majority of researchers qualifies the rodent's floating response as depressive-like behavior. However, over the past few years we also note a trend to interpret immobility rather as the expression of a coping strategy. In view of this result, we have sent a poll to the relevant authors to learn how consistent they are in naming FST behavior. Remarkably, we find a dramatic inverse correlation between their first qualification of acquired immobility as depressive-like behavior towards their current interpretation as coping strategy. In this contribution we have embedded our literature analysis and poll results in an update on the management of coping with inescapable stressors by processing in prefrontal cortical circuitry and glucocorticoid feedback.