The Mouse Forced Swim Test

The mouse forced swim test is a common test used to predict antidepressant efficacy. This movie demonstrates the procedures of the mouse version of the forced swim test. The mouse version is different from the wrap version and should not be used interchangeably.

In the forced swim test, mice are placed in a tank filled with water. The mouse remains in the tank for six minutes. The subject's behaviors are recorded during this time.

At the end of the six minute test period, the subject is taken out of the water. After the test is completed, the visual recordings are transferred to a computer or video monitor. For analysis in observer measures the time a mouse spends struggling during the last four minutes of the six minute session.

Antidepressant medications increase the amount of time by spend struggling. This is reflected by shorter periods of immobility time. Hello, my name is Sean from the laboratory of Dr.Todd Gould at the University of Maryland School of Medicine.

Hi, I am Chantelle from the same lab. In this video, we are going to show you how to perform and score the mouse version of the Forced Swim Test. The mouse forced swim test is used to evaluate the potential efficacy of antidepressant treatments.

So let's dive in, shall we? We use transparent cylindrical tanks made of a sturdy material, such as plexiglass dimensions of the tank are selected to prevent the mice from escaping and touching the bottom with either their feet or tail. Fill the tank with tap water to the predetermined and marked level, adjust the water temperature.

It should be between 23 and 25 degrees Celsius. The water tanks should be arranged for videotaping. In our lab, we perform the forced swim test with four to five subjects at a time between the tanks.

We place dividers to prevent subjects from observing each other. These dividers also provide background contrast with the mice. For albino mice, black provides good contrast for video recordings.

For darker colored mouse strains, a white or cream background is appropriate. Before commencing the experiment, start the white noise machine. Make sure it is not too loud.

It should only mask any intermittent noises. Bring the subjects into the experiment room. To acclimate this period is generally at least one hour.

The conditions in the experiment room should be held constant and free from noises, changes in light levels and other possible disruptions. Once the habituation period ends, the test can be started. It is important to record the session name First, hold the mice by their tails and gently place them into the tank.

It is important to do this slowly so the animals can orient themselves when they touch the water surface. At the end of the six minute test period, video record the identification of animals and stop the recording. Remove the mice in the same order that they were started and gently dry them with paper towels before putting them back in the cage.

The water in the tanks should not be reused. Now that we've completed testing, let's move on to scoring the behaviors In the Mass Force Swim test. The main variable that is assessed is the amount of time that the animals remain immobile during the trial.

Generally in the mouse forced swim test, the last four minutes of the total six minute session is scored. The reason for this is the fact that most mice, regardless of treatment, are continuously mobile in the early stages of the test. This activity overshadows any potential treatment effects.

As you can see in this video, the mice are very active during the initial stages of the test. This activity will decrease after the first two minutes for each mouse time spent. Mobile is measured by an onscreen stopwatch controlled by a game pad.

The other stopwatch counts down the 240 seconds. Test time mobility is defined as any movements other than those necessary to balance the body and keep the head above the water end quote. Now, let's see a sample scoring of a trial.

We first cover the other mice that are not being assessed to prevent confusion. Mice generally float in water readily. However, they still manifest small movements to balance their bodies and keep their heads above the water.

These behaviors are not an attempt to escape and should not be scored as mobility. Also, after a single bout of mobility mice, even though essentially immobile still can drift in the water as a result of the momentum gained earlier, these movements also should not be scored as mobility. Now let's move on to another video.

The mouse in this video displays periods of both mobility and immobility as labeled on the screen, an observ will record mobility time. While it is theoretically possible to measure the immobility time directly, it's easier to detect and measure active movements rather than the lack of such movements. Traditionally immobility time is reported.

Immobility time is determined by subtracting mobility time from 240 seconds. Scoring the fourth swim test takes a lot of training and practice. In order to reach high levels of reliability, it's important to create an internal life standard and train each new observer until they reach high levels of reliability.

In this video, we explain the mouse version of the Forced Swim test. Good luck with your future experiments.