science

Tail suspension test

Tail suspension test is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Tail suspension test rather than just read about it. In short: The tail suspension test (TST) is an experimental method used in scientific research to measure stress in rodents. It is based on the observation that if a mouse is subjected to short term inescapable stress then the mouse will become immobile.

Key takeaways

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Reproduce the core statement of Tail suspension test from memory before moving on to harder problems.

Reference excerpt

The tail suspension test (TST) is an experimental method used in scientific research to measure stress in rodents. It is based on the observation that if a mouse is subjected to short term inescapable stress then the mouse will become immobile. It is used to measure the effectiveness of antidepressant-like agents but there is significant controversy over its interpretation and usefulness.

History The TST was introduced in 1985 due to the popularity of a similar test called the forced swim test (FST). However this test only recently became popular in the 2000s where data has shown that animals do show a change in behavior when injected with antidepressants. TST is more reliable when done in conjunction with other depression models such as FST, learned helplessness, anhedonia models, and olfactory bulbectomy.

Modeling depression Depression is a complex multi-faceted disorder with symptoms that can have multiple causes such as psychological, behavioral, and genetics. Since there are so many variables it is hard to model in a lab setting. Patients with depression do not always show the same set of symptoms and often present with co-occurring psychiatric conditions. A major difficulty in modeling depression is that psychiatrists who clinically diagnose depression follow the Diagnostic and Statistical Manual (DSM IV) of the American Psychiatric Association, which involves self-reporting from patients on how they feel. Since animals cannot explain to us how they feel, animals cannot be diagnosed as clinically depressed. While there are theories that animals can experience a condition similar to depression, it is important to keep in mind that depression is, by definition, a human disease. Human and animal brains are considerably different, and care must be taken when interpreting animal behavior and assigning emotional states to various behaviors. However, there are discrete elements of depression that can be modeled in a lab setting. Stress induced immobilization is a behavior that can be useful in modelling aspects of depression. If a rodent is subjected to the short term inescapable stress of being suspended in the air it will develop an immobile posture. Immobility in the TST can be interpreted as the animal ceasing to put in the effort to try to escape. This is often interpreted as behavioral despair, and could be considered a model of the hopelessness and despair experienced by those with depression. The main strength of the tail suspension test is its predictive validity– performance on the test can be altered by drugs that improve depressive symptoms in people. Specifically, if antidepressant agents are administered before the test, the animal will struggle for a longer period of time than if not and exhibit more escape behaviors. Thus, it is widely used for assessing the antidepressant effects of new pharmacological compounds.

Procedure The animal is hung from a tube by its tail for five minutes approximately 10 cm away from the ground. During this time the animal will try to escape and reach for the ground. The time it takes until it remains immobile is measured. Each animal is tested only once and out of view from the other animals. Within the study there should be two sets of rats, one group which is the control which has been injected with saline and the group being tested which has been injected with the antidepressant-like agents.

Controversy There are mixed opinions about the TST. A common criticism is that it can be weeks before a noticeable effect is observed in patients who take antidepressants regularly, however the TST only measures one acute antidepressant dose for 5–6 minutes. The TST has predictive reliability for known antidepressant agents. However, when testing drugs of unknown mechanisms, the prediction rate is unclear. While the TST detects NK1 receptor antagonists, which have known antidepressant action, it doesn't detect CRF1 receptor antagonists which also have antidepressant functions. Some consider the TST to be a test of antidepressant function, rather than a model of depression itself. This is largely because the test measures behavioral response to a short-term stressor, whereas human depression is a long-term condition.

Difference from the forced swim test TST is more sensitive to antidepressant agents than the FST because the animal will remain immobile longer in the TST than the FST. The FST is not as reliable as the TST because the immobility in the animal could be due to the shock of being dropped in water. This also risks hypothermia. While the mechanisms through which the TST and FST produce stress are unknown it is clear that while overlapping the tests produce immobility through stress differently.

See also Animal models of depression Behavioural despair test Learned helplessness Open field (animal test)

References

Illustrations

Worked examples

Example 1 — a first encounter with Tail suspension test

Start with the simplest possible case. Write down what Tail suspension test claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Tail suspension test before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Tail suspension test ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Tail suspension test

In research: Tail suspension test appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Tail suspension test in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Tail suspension test is common in secondary-school and first-year university syllabi. It links to neighbouring topics Animal testing techniques, Psychology experiments, so understanding it makes those chapters shorter.
In everyday life: Look for Tail suspension test outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Tail suspension test in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Tail suspension test means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Tail suspension test out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Tail suspension test in simple terms?

Why does Tail suspension test matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Tail suspension test?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Tail suspension test.