Using the rat forced swim test to assess antidepressant-like activity in rodents.

The forced swim test (FST) is one of the most commonly used animal models for assessing antidepressant-like behavior. This protocol details using the FST in rats, which takes place over 48 h and is followed by the video analysis of the behavior. The swim test involves the scoring of active (swimming and climbing) or passive (immobility) behavior when rodents are forced to swim in a cylinder from which there is no escape. There are two versions that are used, namely the traditional and modified FSTs, which differ in their experimental setup. For both versions, a pretest of 15 min (although a number of laboratories have used a 10-min pretest with success) is included, as this accentuates the different behaviors in the 5-min swim test following drug treatment. Reduction in passive behavior is interpreted as an antidepressant-like effect of the manipulation, provided it does not increase general locomotor activity, which could provide a false positive result in the FST.