Inducing Depression-like Behavior in a Mouse via Immobilization Stress

Place an isolated and acclimatized mouse in a testing room under moderate lighting to avoid sudden stress.

In a stress-free state, the brain neurons release glutamate, an excitatory neurotransmitter that binds to the receptors on neighboring neurons, facilitating signal transmission.

Gently hold the mouse by the tail to prevent tensing or muscle tightening, then place it on a rough surface.

Next, position the mouse near a covered restrainer, encouraging its voluntary entry into the dark hole within the restrainer.

Immobilize the mouse in the restrainer without injury, inducing immobilization stress.

Repeat this immobilization process over multiple sessions to induce chronic stress, triggering the release of corticosterone, a stress hormone.

Corticosterone diffuses inside the neurons and binds to their glucocorticoid receptors, triggering intracellular signaling that reduces the number of glutamate receptors.

This reduces glutamate response and signal transmission, leading the mouse to develop depression-like behaviors with a decreased interest in activities.

Begin by setting the room to light at 200 lux, using a digital lux meter. 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 minutes before the experiment. Gently hold the mouse tail to avoid tensing the mouse, and then carefully place it on a rough surface.

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. Next, 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.