The Forced Swim Test as a Model of Depressive-like Behavior

Summary

This protocol describes the forced swim test, which is used for the study of depressive-like behavior in rodents. This procedure involves placing an animal in a container filled with water that eventually will lead to the exhibition of immobility behavior, which is considered to reflect behavioral despair.

Abstract

The goal of the present protocol is to describe the forced swim test (FST), which is one of the most commonly used assays for the study of depressive-like behavior in rodents. The FST is based on the assumption that when placing an animal in a container filled with water, it will first make efforts to escape but eventually will exhibit immobility that may be considered to reflect a measure of behavioral despair. This test has been extensively used because it involves the exposure of the animals to stress, which was shown to have a role in the tendency for major depression. Additionally, the FST has been shown to share some of the factors that are influenced or altered by depression in humans, including changes in food consumption, sleep abnormalities and drug-withdrawal-induced anhedonia. The main advantages of this procedure are that it is relatively easy to perform and that its results are easily and quickly analyzed. Moreover, its sensitivity to a broad range of antidepressant drugs that makes it a suitable screening test is one of the most important features leading to its high predictive validity. Despite its appeal, this model has a number of disadvantages. First, the issue of chronic augmentation is problematic in this test because in real life patients need to be treated for at least several weeks before they experience any relief from their symptoms. Last, due to the aversiveness of the FST, it is important to take into account possible influences it might have on brain structure/function if brain analyses are to be carried out following this procedure.

Introduction

Depression is a life-threatening psychiatric disorder and a major public health concern worldwide with an incidence of 5% and a lifetime prevalence of 15-20%. Moreover, it is estimated that by 2020 depression will be in the top three contributors to the burden of disease^1,2. Depression is associated with disability, decreased quality of life, increased health-related costs and is considered a main risk factor for many diseases, including cardiovascular, metabolic and neuropsychiatric disorders^3,4.Current pharmaco-therapeutic treatments have limited efficacy and are associated with many deleterious side effects^5,6. Therefore, a better u....

Protocol

NOTE: All experimental protocols were approved by the International Committee for Animal Care and Use in Israel. All efforts were made to minimize the number of animals used and their suffering.

1. Preparation for the Forced Swim Test

1. Use two adjacent rooms. Use one room as a “waiting room” for holding the animals prior to behavioral testing, and the other for carrying out the procedure.
2. Prepare transparent cylindrical glass containers (the only restriction for the number of containers is the space available) measuring 50 cm in height and a diameter of 20 cm.
   NOTE: It is possible to run several anima....

Results

The following results are based on unpublished data from our lab. In this experiment, adult ICR female mice were tested after 3 weeks of treatment with the selective serotonin reuptake Inhibitor (SSRI) escitalopram or novel herbal anti-depressive and anti-anxiety treatment (NHT) (for additional information regarding the herbal treatment, see ^12,27,28). One-way ANOVA revealed that the treatment reduced depressive-like behavior in the FST [F(2,58) = 4.88, p <0.05]. One-sided Dunnet analysis revealed that trea.......

Discussion

The FST is used to monitor depressive-like behavior and is based on the assumption that immobility reflects a measure of behavioral despair ³. The main advantages of this procedure lie in its relatively easy operation and fast results. Moreover, its sensitivity to a broad range of antidepressant drugs that makes it a suitable screening test is one of the most important features leading to its high predictive validity ²⁹. Importantly, this test can also differentiate between drugs that are not aimed .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Computer	Dell		Intel® Core™ i3-2120 cpu @ 3.30 GHz, 4 GB ram
Camera	VIDO	AU-CB422	B/W CCD CAMERA  http://www.vido-europe.com/products_detail.asp?id=33&pcategory=2
Coding software	Biobserve		FST Analysis http://www.biobserve.com/products/fst/index.html
Heating lamp	Ikea	AA-19025-3	ESPRESSIVIO 400.504.46 - 20W G4 Bulb  http://www.ikea.com/ms/en_US/customer_service/assembly/E/E00050467.pdf
Heating pillow	Sachs	EF-188B	38*38cm Heating pillow http://www.sachs.co.il/eng/lego_tree.php?instance_id=21&actions=show&id= 604