The Tail Suspension Test

The tail suspension test is a common behavioral test used to predict antidepressant efficacy of various experimental manipulations. This movie demonstrates the procedures of this test. The tail suspension test is validated for the mouse and is not recommended for larger rodents.

In the tail suspension test mice are suspended by their tails. The mouse remains suspended for six minutes. The subject's behaviors are recorded during this time.

At the end of the six minute test period, the tape is removed from the tail of the subject. After the test is completed, the visual recordings are transferred to a computer or video monitor. For analysis, an observer measures the time a mouse spends struggling during the entire six minute session.

Compounds with antidepressant properties increase the amount of time my spend struggling. This is reflected by shorter periods of immobility. For example, we have reported that the mood stabilizing medication lithium, which is clinically useful as an adjunct antidepressant medication, decreased immobility time in the tail suspension test.

Hello, my name is Sean from the laboratory of Dr.Todd Gould in the Department of Psychiatry at the University of Maryland School of Medicine in Baltimore. Hi, I'm Chantel from the same lab. In this video, we are going to show you how to perform and score the tail suspension test.

Tail Suspension test is used to evaluate the potential efficacy of antidepressant treatments. So let's go to the lab and show you how to run the experiment. Though not required, we use specially designed tail suspension box.

For this test. Our tail suspension box is divided into four compartments, each reserved for a single mouse. The dividers prevent the mice from observing each other during the test.

However, it is possible to use a shelf or other structure to suspend the mice. Dimensions of the tail suspension test box are selected to prevent the mice from reaching and holding onto the edges. Before starting the experiment, cut enough tape fragments and mark the segment that is going to be used for adhesion to the tail.

In our lab, we will be using 17 centimeter tape fragments. Two centimeters from the end of this tape fragment should be marked and will be used to adhere to the tail. We place the tail in the middle of this two centimeter portion.

Position the tail suspension test box, and the video camera. Before introducing the animals, the box should be thoroughly cleaned with a sterilizing solution for neutralizing the odors left from the previous subjects. In our laboratory, we use two different tail suspension boxes, identical in every aspect except the color.

For albino mice, a dark gray box provides good contrast for video recordings. For darker colored mouse strains, a white box is appropriate. Start the white noise machine.

It should mask any intermittent sounds. Bring the mice into the procedure room to acclimate. The conditions in the room should be held constant and free from noises, changes in light levels and other possible disruptions.

This period is generally at least one hour. Once the acclimation period ends, the test can then proceed in order to prevent certain mouse strains from climbing their tails. During the tail suspension test, we use plastic cylinders that we place over the tails.

These cylinders rest at the base of their tail during the test. In our laboratory, we use plastic cylinders that are four centimeters long, one centimeter in diameter, and weigh 1.5 grams. If plastic cylinders are being used to prevent climbing, they should be placed on the tails prior to applying the tape.

We apply tape to the very end of the tail with two to three millimeters of the tail remaining outside of the tape. Adhere the tape to the tails of the mice in their home cage. Use the marked end of the tape and make sure the tape sticks to the tail and back on itself.

Once the tape is applied, secure each mouse to the walls of the cage in order to prevent tangling of the tape attached to different animals. Complete this process quickly. Otherwise, the mice will be subjected to unnecessary stress.

The recording should be started before the animals are suspended. Suspend the animals by placing the free end of the tape on the suspension bar in an order that is counterbalanced between treatment groups and in a way that does not obstruct the camera view. Because mice are suspended one by one, each animal has a slightly different start time for the test.

Make sure you start scoring each mouse exactly at the beginning of its suspension period. Not obstructing the camera view is important. Since the entire tail suspension session will be scored obstructing, the camera view could lead to missing data.

Be certain that all tape ends are perpendicular to the suspension bar with the same length of slack. For each subject, start the timer. The tail suspension test is six minutes.

Once the six minute test period elapses, remove the tape from the end of each tail and return the mice to their home cage. At the end of the test, the subject information should be video recorded. After the mice are returned to the colony room, the test box should be thoroughly cleaned and wiped with a sterilization solution.

Now that we have finished with the testing, we will discuss scoring the behaviors. The only variable that is typically assessed when scoring the tail suspension test is the time that the animals are immobile To obtain immobility time, we will measure the time that the mice are mobile and deduct that from the six minute test time. We will be scoring the entire six minutes of the test.

We first cover the mice that are not being assessed to allow the observer to focus on one animal only for each mouse time spent. Mobile is measured by an onscreen stopwatch controlled by a gamepad device. Here, as you can see, there are two separate onscreen stopwatches that are controlled simultaneously.

The first stopwatch counts down from 360 seconds and indicates the test duration to the observer. The second stopwatch measures the time that subjects stay mobile. As you may notice, the second stopwatch is covered by the first stopwatch and only its millisecond decimals are visible to the observer.

In this way, the observer will be able to see if the stopwatch is counting, but cannot see total mobility time until the scoring is completed. We do this to prevent observer bias from affecting the results. Mice, especially at the beginning of the session, manifest escape related behaviors.

These behaviors include trying to reach the walls of the apparatus and the suspension bar, strong shakes of the body and movements of the limbs akin to running. These movements clearly constitute mobility. However, as the test progresses, movements become more subtle.

In our laboratory, we do not count the small movements that are confined to the front legs, but without any movement of the hind legs as mobility. In addition to this pendulum like swings that are due to the momentum gain during the previous mobility bouts are not considered mobility. Now let's see the scoring of an actual tail suspension test session.

Immobility time, not mobility time is generally reported. Immobility time can be calculated by subtracting the total mobility time from the 360 seconds test time.Scoring. The tail suspension test takes training and practice.

It is important to establish an internal lab standard and to train new observers until they reach a high level of reliability. In this paper, we explain how perform and score the tail suspension test. Good luck with your future experiments.