This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2015R1A5A2008833 and NRF-2016R1D1A3B03934279) and the grant of lnstitute of Health Sciences (IHS GNU-2016-02) at Gyeongsang National University.

All experimental protocols and animal care were conducted according to the guidelines of the University Animal Care Committee for Animal Research of Gyeongsang National University (GLA-100917-M0093).
1. Materials
<ol>
	<li>Mice
	<ol>
		<li>Use males of C57BL/6 strain background weighing 22&#8211;24 g at postnatal week 7. Habituate in the breeding room for 1 week before the experiments. 
		NOTE: All mice were purchased from a laboratory animal company.</li>
		<li>House mice individually in a temperature-controlled vivarium (22&#8211;24 &#176;C) under a 12-hour light/dark cycle (lights on at 6:00 A.M.), with normal laboratory chow and water available ad libitum.</li>
	</ol>
	</li>
	<li>Restrainer
	<ol>
		<li>Use a cylindrical, transparent, acrylic tank (height = 8.5 cm, diameter = 2.5 cm) fixed on a square pedestal to restrain and to produce depressive behavior (Figure 1A). The diameter of this cylinder was made to fit the body so that the mouse could not turn and move forwards or backwards. The restrainer can be purchased commercially or made in the lab.</li>
	</ol>
	</li>
	<li>Tail suspension apparatus
	<ol>
		<li>Use a reasonable size tail suspension box made of translucent acrylic (height = 30 cm, width = 20 cm, length = 20, Figure 1B). To prevent interactions between the animals, use rectangular partitions within the box so that the floor and three of the four walls are blocked by acrylic plates. Leave the remaining two sides of the box open to allow video recording and to fix the horizontal bar. The box can be purchased commercially or made in the lab.</li>
	</ol>
	</li>
	<li>Video recording device and video tracking software
	<ol>
		<li>Use a black and white-display closed-circuit television camera (see Table of Materials) connected to a computer and a tripod (or other support products) to allow recording of the behavioral experiment. Video recording is essential to allow behavioral scoring in this experiment, because at least two mice are tested at the same time.</li>
		<li>Ensure that the camera resolution is high enough to allow the video data to be analyzed using the video tracking software (see Table of Materials) installed in the connected computer.</li>
	</ol>
	</li>
</ol>
2. Induction of depression by CIS restraint
NOTE: Handle the mouse gently, but firmly with confidence. Both rough and tentative handling is another stress factor in the experiment and it is an important reason for the mouse struggling, biting, and scratching.
<ol>
	<li>Set the room light to light (200 Lux) conditions using a digital lux meter.</li>
	<li>House the mouse in a separate cage at least a week before testing and place the mouse in the testing room for at least 30 min before the experiment. 
	NOTE: Handle the mice at least once a day for at least 3 consecutive days before the experiment so that the mice become familiar with the experimenter. An adaptational period before the experiment is necessary to ensure that the mice acclimatize to the circumstance, such as the testing room.</li>
	<li>Gently hold the mouse tail to avoid tensing the mouse, and then carefully place it on a rough surface (top of wire bar of the cage or cage lid).</li>
	<li>Cover the restrainer with a small white towel, and then gently place the mouse at the opening of the restrainer so that the mouse enters the restrainer voluntarily. 
	NOTE: In this case, the mouse is positioned in the opposite direction to that which it enters the restrainer with. To lead the mouse to enter the restrainer voluntarily, the restrainer is covered with a small towel to make the inside darker.</li>
	<li>Place the closure to restrain the mouse as tight as possible, being careful to avoid damage to the body, such as tail, feet, and testicles.</li>
	<li>Restrain the mouse for 2 h/day (9:00 A.M. to 11:00 A.M.) for 15 consecutive days.</li>
	<li>Measure body weight and food intake every 48 h&#160;during exposure to the restrainer (i.e., food intake quantity during the 48 h&#160;before the initiation of the movement restraint). 
	NOTE: When measuring body weight and food intake, place control mice in their home cages in the testing room during CIS. Ensure that other environmental factors are the same as for the CIS mice.</li>
	<li>Confirm the induction of depression by performing behavioral tests such as the sucrose preference test (SPT) and the tail suspension test (TST) (refer to steps 4 and 5).</li>
	<li>Confirm the induction of depression by measuring the stress marker corticosterone using ELISA assay (refer to section 6).</li>
</ol>
3. The sucrose preference test
<ol>
	<li>Before testing, habituate the mice to the presence of two drinking bottles (one containing 0.1 M sucrose and the other containing plain water) for 48 h. Switch the positions of the two bottles after 24 h&#160;to reduce any confounding produced by a side bias.</li>
	<li>On the 3rd day, deprive the mice of water for 24 h.</li>
	<li>On the day of the SPT experiment, expose the mice to two drinking bottles for 6 h. After 3 h, switch the position of the water bottles.</li>
	<li>Record the volume (mL) of sucrose solution and water consumed and then calculate the animals&#8217; affinity to sucrose.</li>
	<li>Generally, calculate sucrose preference as a percentage of the volume of sucrose consumption over the total fluid consumption during the test.</li>
</ol>
4. The tail suspension test
<ol>
	<li>Bring the CIS-induced mice into the testing room at least 30 min&#160;before beginning the TST.</li>
	<li>Set the room light to dim (50 Lux) conditions.</li>
	<li>To obtain the highest resolution video file, place the camera as close to the mouse as possible (around 40 cm from the mouse).</li>
	<li>Suspend the mouse firmly from the horizontal bar (30 cm from the bottom line) using cellophane adhesive tape (the distance from the tip of the tail is 1 cm). Complete the process of applying tape to the mouse as soon as possible to minimize other sources of stress.</li>
	<li>Once the mouse is positioned in the middle of suspension box, start recording and observe the behavioral alterations continuously for 6 min. 
	NOTE:&#160;If the mouse attempts to climb its tail, use a stick or climb stopper to prevent it from doing so.</li>
	<li>At the end of the experiment, move the mouse to its home cage and carefully remove the tape from its tail.</li>
	<li>Analyze the accumulated time of immobile periods using the video tracking software. 
	NOTE: The duration of immobility is the most important CIS parameter. This can be calculated as the accumulated time of immobile periods, defined in terms of a motion threshold contained within the level-filtering device of the software.</li>
</ol>
5. Measuring corticosterone levels in blood by ELISA
NOTE: A day after the behavioral test, the mice are sacrificed for blood collecting.
<ol>
	<li>Anesthetize the mouse with 5% isoflurane in an induction chamber until anesthesia. Ensure the mouse has sufficient time in the induction chamber (at least 2 min) to prevent waking up during surgery.</li>
	<li>Collect blood from the heart using a 1 mL syringe, and store the blood in vacutainers containing K3EDTA on the ice (at 9 A.M.)</li>
	<li>Separate plasma by centrifugation at 1,000&#8239;&#215;&#8239;g for 15&#8239;min&#8239;at 4&#8239;&#176;C.</li>
	<li>Quantify plasma corticosterone levels using the corticosterone ELISA kit (see Table of Materials) according to the manufacturer&#39;s protocol.</li>
</ol>

The authors have nothing to disclose.

The complexity of the brain and heterogeneity of MDD make it challenging to create animal models that completely reproduce the condition. Many researchers have overcome this difficulty using an endophenotype-based approach32, in which anhedonia (lack of interest in rewarding stimuli) and despair are considered evolutionarily conserved and quantifiable behaviors in animal models, which are also seen in patients with depression33. In the present paper, we have presented a met...

Major depressive disorder (MDD) is the leading cause of mental disability worldwide, with an incidence that is increasing faster than anticipated. In 2001, the World Health Organization predicted that MDD would be the second most common disease in the world by 2020. However, it was already the second most common in 20131. In addition, current antidepressants have many limitations, including delayed effectivity, drug resistance, relapse, and various side effects2,3. Researchers must therefore develop more effective antidepressants. However, the ambiguous pathophysiology of MDD presents an obstacle to the development of novel antidepressants.
Long-term stress is the main risk factor for MDD. It can induce dysfunction in the hypothalamic-pituitary-adrenal (HPA) axis, which is also related to MDD etiology4,5. As described previously, the HPA axis plays a critical role in stress-induced psychiatric pathophysiology including depression and anxiety disorders by increasing corticosterone levels6,7,8,9. Many animal models have been based on sustained activation of the HPA axis, which is observed in patients with MDD4. Moreover, high glucocorticoids induced by chronic stress and subcutaneously&#160;injected glucocorticoids cause depressive behaviors along with neural cell death, atrophy of neuronal processes, and reduced adult neurogenesis in the brain of rodents10,11. Another important brain area associated with depression is the medial prefrontal cortex (mPFC). The mPFC plays a crucial role in controlling brain subregions, such as the hypothalamus and amygdala, that control emotional behavior and stress responses8,9. For instance, lesions in the dorsal mPFC induced HPA axis dysfunction and enhanced corticosterone secretion due to restraint stress12,13. A recent study also showed that repeated restraint stress increased corticosterone levels, which could be decreased by glutamine supplementation via glutamate-glutamine cycle between neurons and astrocyte in the mPFC9.
The first chronic stress paradigm used to study the etiology of MDD was suggested by Katz14. Willner et al. then proposed a chronic mild stress (CMS) model based on the findings of Katz. They confirmed that the model had predictive validity by observing that antidepressants restored CMS-induced anhedonic-like behavior15,16. Typically, the CMS model consists of a combination of various mild stresses, such as mild noise, cage tilting, wet bedding, altered light-dark cycles, cage shaking, forced swimming, and social defeat. The CMS model is widely utilized by researchers; however, this model is of poor replicability, and time- and energy-inefficient. Therefore, there is a growing demand for a standardized and simplified protocol for induction of depressive-like behavior and physiological analysis to evaluate depression. Compared to the CMS model, the chronic immobilization stress (CIS; also known as chronic restraint stress) model is simpler and more efficient; therefore, the CIS model can be widely used in chronic stress studies17,18,19,20,21,22,23,24. In addition, CIS can be used in both male and female mice to develop depressive behaviors25,26. During CIS, animals are placed in a body-fit sized cylinder for 1-8 hours per day for 2 or 4 weeks9,27,28. Of these, restraint stress condition for 2 hours per day for 2 weeks is sufficient to cause depressive behaviors with minimal pain in mice9,28. Under restraint conditions, blood corticosterone levels were rapidly increased9,28,29. Several studies have shown that the CIS model has predictive validity, confirming that CIS-induced depressive-like symptoms are restored by antidepressants19,20,30,31. Herein, we report the detailed procedures of CIS, as well as some behavioral and physiological outcomes after CIS in mice.

<table><tbody><tr><td>1 ml disposable syringes</td><td>Sungshim Medical</td><td>P000CFDO</td><td></td></tr><tr><td>Balance</td><td>A&amp;amp;D Company</td><td>FX-2000i</td><td></td></tr><tr><td>Ball nozzle</td><td>Jeung Do B&amp;amp;P</td><td>JD-C-88</td><td></td></tr><tr><td>CCTV camera</td><td>KOCOM</td><td>KCB-381</td><td></td></tr><tr><td>Corticosterone ELISA kits</td><td>Cayman Chemical</td><td></td><td></td></tr><tr><td>Digital lux meter</td><td>TES</td><td>TES-1330A</td><td></td></tr><tr><td>Ethovision XT 7.1</td><td>Noldus Information Technology</td><td></td><td></td></tr><tr><td>Isoflurane</td><td>HANA PHARM CO., LTD.</td><td></td><td>Ifran solution</td></tr><tr><td>Mice</td><td>Koatech</td><td></td><td>C57BL/6 strain</td></tr><tr><td>Restrainer</td><td>Dae-jong Instrument Industry</td><td>DJ-428</td><td></td></tr><tr><td>Saccharose (sucrose)</td><td>DAEJUNG</td><td>7501-4400</td><td></td></tr><tr><td>Small animal isoflurane anaesthetic system</td><td>Summit</td><td></td><td></td></tr><tr><td>Acrylic bar</td><td></td><td></td><td>The apparatus was made in the lab for TST test</td></tr><tr><td>Tail suspension box</td><td></td><td></td><td>The apparatus was made in the lab</td></tr><tr><td>Timer</td><td>Electronics Tomorrow</td><td>TL-2530</td><td></td></tr><tr><td>Water bottle</td><td>Jeung Do B&amp;amp;P</td><td>JD-C-79</td><td></td></tr></tbody></table>

a chronic immobilization stress protocol for inducing depression-like behavior in mice

Depression is not yet fully understood, but various causative factors have been reported. Recently, the prevalence of depression has increased. However, therapeutic treatments for depression or research on depression is scarce. Thus, in the present paper, we propose a mouse model of depression induced by movement restriction. Chronic mild stress (CMS) is a well-known technique to induce depressive-like behavior. However, it necessitates a complex procedure consisting of a combination of various mild stresses. In contrast, chronic immobilization stress (CIS) is a readily accessible chronic stress model, modified from a restraint model that induces depressive behavior by restricting movement using a restrainer for a certain period. To evaluate the depressive-like behaviors, the sucrose preference test (SPT), the tail suspension test (TST), and the ELISA assay to measure stress marker corticosterone levels are combined in the present experiment. The described protocols illustrate the induction of CIS and evaluation of the changes in behavior and physiological factors for the validation of depression.

In the representative experiment, all data were acquired from 6 - 8 mice per group. Representative materials and the method to insert the mouse voluntarily into the restrainer are shown in Figure 1.
To perform the behavioral test and blood sampling after CIS induction, mice were subjected to the experimental procedure as summarized in Figure 2A. As shown in Figure 2 and Figure 3</stro...

Watch this Scientific Journal Video about A Chronic Immobilization Stress Protocol for Inducing Depression-Like Behavior in Mice at JoVE.com

A Chronic Immobilization Stress Protocol for Inducing Depression-Like Behavior in Mice

This article provides a simplified and standardized protocol for induction of depressive-like behavior in chronically immobilized mice by using a restrainer. In addition, behavior and physiological techniques to verify induction of depression are explained.

Depression is not yet fully understood, but various causative factors have been reported. Recently, the prevalence of depression has increased. However, ...

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21.8K Views.  Gyeongsang National University Medical School. This article provides a simplified and standardized protocol for induction of depressive-like behavior in chronically immobilized mice by using a restrainer. In addition, behavior and physiological techniques to verify induction of depression are explained.

Video: A Chronic Immobilization Stress Protocol for Inducing Depression-Like Behavior in Mice

A Mouse Model of Subchronic and Mild Social Defeat Stress for Understanding Stress-induced Behavioral and Physiological Deficits

Stressful life events often increase the incidence of depression in humans. To study the mechanisms of depression, the development of animal models of depression is essential. Because there are several types of depression, various animal models are needed for a deeper understanding of the disorder. Previously, a mouse model of subchronic and mild social defeat stress (sCSDS) using a modified chronic social defeat stress (CSDS) paradigm was established. In the paradigm, to reduce physical injuries from aggressors, the duration of physical contact between the aggressor and a subordinate was reduced compared to in the original CSDS paradigm. sCSDS mice showed increased body weight gain, food intake, and water intake during the stress period, and their social behaviors were suppressed after the stress period. In terms of the face validity of the stress-induced overeating and overdrinking following the increased body weight gain, the sCSDS mice may show some features related to atypical depression in humans. Thus, a mouse model of sCSDS may be useful for studying the pathogenic mechanisms underlying depression. This protocol will help establish the sCSDS mouse model, especially for studying the mechanisms underlying stress-induced weight gain and polydipsia- and hyperphagia-like symptoms.

Here, methods for developing a mouse model of subchronic and mild social defeat stress are described and used to investigate the pathogenic features of depression including hyperphagia- and polydipsia-like symptoms following increased body weight.

Stressful life events often increase the incidence of depression in humans. To study the mechanisms of depression, the development of animal models of ...

An Unpredictable Chronic Mild Stress Protocol for Instigating Depressive Symptoms, Behavioral Changes and Negative Health Outcomes in Rodents

Chronic, unresolved stress is a major risk factor for the development of clinical depression. While many preclinical models of stress-induced depression have been reported, the unpredictable chronic mild stress (UCMS) protocol is an established translationally-relevant model for inducing behavioral symptoms commonly associated with clinical depression, such as anhedonia, altered grooming behavior, and learned helplessness in rodents. The UCMS protocol also induces physiological (e.g., hypercortisolemia, hypertension) and neurological (e.g., anhedonia, learned helplessness) changes that are clinically associated with depression. Importantly, UCMS-induced depressive symptoms can be ameliorated through chronic, but not acute, treatment with common SSRIs. As such, the UCMS protocol offers many advantages over acute stress protocols or protocols that utilize more extreme stressors. Our protocol involves randomized, daily exposures to 7 distinct stressors: damp bedding, removal of bedding, cage tilt, alteration of light/dark cycles, social stresses, shallow water bath, and predator sounds/smells. By subjecting rodents 3-4 hr daily to these mild stressors for 8 weeks, we demonstrate both significant behavioral changes and poor health outcomes to the cardiovascular system. This approach allows for in-depth interrogation of the neurological, behavioral, and physiological alterations associated with chronic stress-induced depression, as well as for testing of new potential therapeutic agents or intervention strategies.

The unpredictable chronic mild stress (UCMS) protocol is a validated method for studying behavioral and physiological changes associated with chronic stress and depressive symptoms. Eight weeks of imposition of the UCMS protocol induces behavioral changes and poor health outcomes in rodents of either gender.

Chronic, unresolved stress is a major risk factor for the development of clinical depression. While many preclinical models of stress-induced depression ...

The Unpredictable Chronic Mild Stress Protocol for Inducing Anhedonia in Mice

Depression is a highly prevalent and debilitating condition, only partially addressed by current pharmacotherapies. The lack of response to treatment by many patients prompts the need to develop new therapeutic alternatives and to better understand the etiology of the disorder. Pre-clinical models with translational merits are rudimentary for this task. Here we present a protocol for the unpredictable chronic mild stress (UCMS) method in mice. In this protocol, adolescent mice are chronically exposed to interchanging unpredictable mild stressors. Resembling the pathogenesis of depression in humans, stress exposure during the sensitive period of mice adolescence instigates a depressive-like phenotype evident in adulthood. UCMS can be used for screenings of antidepressants on the variety of depressive-like behaviors and neuromolecular indices. Among the more prominent tests to assess depressive-like behavior in rodents is the sucrose preference test (SPT), which reflects anhedonia (core symptom of depression). The SPT will also be presented in this protocol. The ability of UCMS to induce anhedonia, instigate long-term behavioral deficits and enable reversal of these deficits via chronic (but not acute) treatment with antidepressants strengthens the protocol&#39;s validity compared to other animal protocols for inducing depressive-like behaviors.

Here we present the unpredictable chronic mild stress protocol in mice. This protocol induces a long-term depressive-like phenotype and enables to assess the efficacy of putative antidepressants in reversing the behavioral and neuromolecular depressive-like deficits.

Depression is a highly prevalent and debilitating condition, only partially addressed by current pharmacotherapies. The lack of response to treatment by ...

Low-cost Protocol of Footprint Analysis and Hanging Box Test for Mice Applied the Chronic Restraint Stress

Gait disturbance is frequently observed in patients with movement disorders. In mouse models used for movement disorders, gait analysis is important behavioral test to determine whether the mice mimic the symptoms of patients. Motor deficits are often induced by stress when no spontaneous motor phenotype is observed in the mouse models. Therefore, gait analysis followed by stress loading would be a sensitive method for evaluating the motor phenotype in mouse models. However, researchers face the requirement of an expensive apparatus to obtain quantitative results automatically from gait analysis. For stress, stress loading by simple methods without expensive apparatuses required for electric shock and forced running is desirable. Therefore, we introduce a simple and low-cost protocol consisting of footprint analysis with paper and ink, hanging box test to evaluate motor function, and stress loading defined by restraint with a conical tube. The motor deficits of mice were successfully detected by this protocol.

The low-cost protocol consisting of footprint analysis and hanging box test after restraint stress is useful for evaluating the movement disorders of mouse model.

Gait disturbance is frequently observed in patients with movement disorders. In mouse models used for movement disorders, gait analysis is important ...

Chronic Stress Shifts Effort-Related Choice Behavior in a Y-Maze Barrier Task in Mice

Mood disorders, including major depressive disorder, can be precipitated by chronic stress. The Y-maze barrier task is an effort-related choice test that measures motivation to expend effort and obtain reward. In mice, chronic stress exposure significantly impacts motivation to work for a higher value reward when a lesser value reward is freely available compared to unstressed mice. Here we describe the chronic corticosterone administration paradigm, which produces a shift in effortful responding in the Y-maze barrier task. In the Y-maze task, one arm contains 4 food pellets, while the other arm contains only 2 pellets. After mice learn to select the high reward arm, barriers with progressively increasing height are then introduced into the high reward arm over multiple test sessions. Unfortunately, most chronic stress paradigms (including corticosterone and social defeat) were developed in male mice and are less effective in female mice. Therefore, we also discuss chronic non-discriminatory social defeat stress (CNSDS), a stress paradigm we developed that is effective in both male and female mice. Repeating results with multiple distinct chronic stressors in male and female mice combined with increased usage of translationally relevant behavior tasks will help to advance the understanding of how chronic stress can precipitate mood disorders.

The Y-maze barrier task is a behavior test that examines motivation to expend effort for reward. Here, we discuss testing multiple well-validated chronic stressors including chronic corticosterone and social defeat stress with this behavior, as well as the novel chronic non-discriminatory social defeat stress (CNSDS), which is effective in females.

Mood disorders, including major depressive disorder, can be precipitated by chronic stress. The Y-maze barrier task is an effort-related choice test that ...

Animal Models of Depression - Chronic Despair Model (CDM)

Major depressive disorder is one of the most prevalent forms of mental illnesses and causes tremendous individual suffering and socioeconomic burden. Despite its importance, current pharmacological treatment is limited, and novel treatment options are urgently needed. One key factor in the search for potential new drugs is evaluating their anti-depressive potency in appropriate animal models. The classical Porsolt forced swim test was used for this purpose for decades to induce and assess a depressive-like state. It consists of two short periods of forced swimming: the first to induce a depressed state and the second on the following day to evaluate the antidepressant effect of the agent given in between the two swim sessions. This model might be suitable as a screening tool for potential antidepressive agents but ignores the delayed onset of action of many antidepressants. The CDM was recently established and represented a modification of the classical test with notable differences. Mice are forced to swim for 5 consecutive days, following the idea that in humans, depression is induced by chronic rather than by acute stress. In a resting period of several days (1-3 weeks), animals develop sustained behavioral despair. The standard read-out method is the measurement of immobility time in an additional delayed swim session, but several alternative methods are proposed to get a broader view of the mood status of the animal. Multiple analysis tools can be used targeting behavioral, molecular, and electrophysiological changes. The depressed phenotype is stable for at least 4 weeks, providing a time window for rapid but also subchronic antidepressant treatment strategies. Furthermore, alterations in the development of a depressive-like state can be addressed using this approach. CDM, therefore, represents a useful tool to better understand depression and to develop novel treatment interventions.

Animal Models of Depression - Chronic Despair Model CDM

The chronic despair mouse model (CDM) of depression consists of repetitive forced swim sessions and another delayed swim phase as a read-out. It represents a suitable model for induction of a chronic depressive-like state stable for at least 4 weeks, amendable to evaluate subchronic and acute treatment interventions.

Major depressive disorder is one of the most prevalent forms of mental illnesses and causes tremendous individual suffering and socioeconomic burden. ...

Modeling Early Life Trauma in Mice to Study PTSD and Social Avoidance Behavior

Chronic Social Defeat Stress in Early Adolescent Male Mice

Physical abuse and trauma in childhood is reported in as many as 1 in 7 children and is a major risk factor for the development of psychiatric diseases, such as Post-Traumatic Stress Disorder (PTSD), in adolescence and adulthood. Hallmark behavioral symptoms of PTSD include avoidance of cues and contexts associated with trauma. The ability to model long-lasting changes in the brain due to early life trauma is critical to determine potential circuit and molecular targets for the modulation of resultant symptoms. This manuscript describes a protocol for modeling early life physical and psychological trauma in early adolescent male mice that produces socially avoidant behavior. Adolescent male mice are exposed to repeated aggressive encounters followed by overnight housing, which provides an added dimension of psychological stress, with an adult male aggressor every day for 10 days. Repeated social defeat paired with overnight housing by the aggressor in early adolescence produces robust social avoidance behavior that lasts throughout adulthood. Social avoidance can be readily quantified in early adolescents, adolescents, and adults using open field social interaction testing. Early adolescent social defeat robustly produces more than 60% susceptible animals in adulthood.

This protocol details how to perform 10 day chronic social defeat stress in early adolescent male mice to produce long-lasting social avoidance in adulthood in more than 60% of mice.

Physical abuse and trauma in childhood is reported in as many as 1 in 7 children and is a major risk factor for the development of psychiatric diseases, ...

Social Isolation Model: A Noninvasive Rodent Model of Stress and Anxiety

Anxiety disorders are one of the leading causes of disability in the United States (US). Current treatments are not always effective and less than 50% of patients achieve full remission. A critical step in developing a novel anxiolytic is to develop and utilize an animal model, such as mice, to study pathological changes and test drug target(s), efficacy, and safety. Current approaches include genetic manipulation, chronic administration of anxiety-inducing molecules, or the administration of environmental stress. These methods, however, may not realistically reflect anxiety induced throughout daily life. This protocol describes a novel anxiety model, which mimics the intentional or unintentional patterns of social isolation in modern life. The social isolation-induced anxiety model minimizes perceived distractions and invasiveness and utilizes wild type C57BL/6 mice. In this protocol, 6- to 8-week-old mice (male and female) are singly housed in opaque cages to visually block the external environment, such as neighboring mice, for 4 weeks. No environmental enrichments (such as toys) are provided, bedding material is reduced by 50%, any treatment of drug is administered as an agar form, and the exposure/handling of the mice is minimized. Socially isolated mice generated using this protocol exhibit greater anxiety-like behavior, aggression,&#160;as well as decreased cognition.

Presented here is a social isolation (SI)-induced anxiety mouse model that utilizes wild type C56BL/6J mice to induce stress and anxiety-like behavior with minimal handling and no invasive procedures. This model reflects modern life patterns of social isolation and is ideal for studying anxiety and related disorders.

Anxiety disorders are one of the leading causes of disability in the United States (US). Current treatments are not always effective and less than 50% of ...

Neuroscience

Inducing Depression-like Behavior in a Mouse via Immobilization Stress

Source: Son, H., et al., <a href="https://app.jove.com/v/59546">A Chronic Immobilization Stress Protocol for Inducing Depression-Like Behavior in Mice.</a> J. Vis. Exp. (2019).
This video demonstrates the method of inducing chronic stress in a mouse through repeated immobilization, leading to corticosterone release and reduced glutamate receptor activity in neurons, which results in depression-like behavior.

Source: Son, H., et al., A Chronic Immobilization Stress Protocol for Inducing Depression-Like Behavior in Mice. J. Vis. Exp. (2019).
This video ...

JoVE Encyclopedia of Experiments

Neuropathology

Neurodegenerative Diseases

Induction and Evaluation of Depression in Mice Through Chronic Stress Exposure

To induce depression, expose mice daily to any two of the following seven stressors for 21 consecutive days. Expose mice to food deprivation by emptying the feed of each cage, or water deprivation by removing the water bottle for 24 hours. Expose mice to restrained stress, where the mouse is restrained in a small plastic tub for three hours, or an empty cage with the padding removed. As another option, expose mice to wet and soiled cages by pouring water into each cage and keeping wet for 24 hours.Expose mice to crowded cages, in which five mice are placed in one cage for 25 hours. For the last option, expose mice to ice cold swimming by forcing each mouse to swim in a clear glass aquarium with ice water for five minutes. Finally, record the coat state and body weight weekly until the end of modeling at day 21, and calculate the total score of the coat's state.