The Tail Suspension Test (TST) is a test commonly used to evaluate antidepressant effects in mice or rats. In the experiment, the animals were suspended from a high place with their tails in the air. The helplessness displayed by the animal in order to escape was used as a measure of the antidepressant effect, i.e., the animal's reduced movement. Antidepressants often reduce this feeling of helplessness. TST is often used for drug screening and studying the neurobiological mechanisms of antidepressant drugs, but its limitations in behavioral models should also be noted.