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

This model mimics human social, isolative life and it is a noninvasive and simple way to create a model of anxiety and mild cognitive impairment. This technique only requires the appropriate housing conditions and treatment auger, and it doesn't require tedious processes like injections or genetic manipulation. For social isolation of the animals, take a standard mouse cage with a 75 inch square floor space.

Add half the amount of bedding and a one-inch square piece of cotton for nesting. Wrap the outside of the cage walls in opaque black plastic bags with no segment of the bag accessible from the inside. Secure the bag using tape and ensure that the animal's outside environment or surroundings are not visible.

Leave the top and bottom of the cage unwrapped unless the mice can see neighboring animals through them. Keep the control mice in groups of two or three under normal caging conditions in a standard mouse cage with a full amount of bedding, a two-inch square piece of cotton or equivalent for nesting, with no wrapping of opaque bags. Ensure the group housed mice are compatible without conflict.

If not, exclude the aggressor from the analysis. Change the cages only once a week during the dark cycle with the same plastic bag rewrapped to a new cage unless significant damage is present. For control mice, change the cages twice a week or more during the dark cycle.

Continue isolating the mice for at least four weeks to observe the optimal results. To prepare the treatment, add 3%agar to deionized water and dissolve it at approximately 90 degrees Celsius using a heating plate or microwave. Prevent the bubbling solution from spillage or boiling over.

Swirl the solution till it becomes homogenous. While the solution is still warm, add 5%sucrose. Swirl the homogenous solution before pouring the solution into a mold.

Let it cool and solidify at room temperature or 4 degree Celsius. In the case of light sensitive treatment, protect the mold from light. Once solidified, cut the agar into cubes of 0.5 by 0.5 by 0.5 centimeters and store at 4 degrees celsius until administration.

Administer the treatment at planned timing and frequency with as little handling as possible. Quietly and carefully place a single cube onto a small way boat or equivalent, such as the cap of a 50 milliliter chronicle tube during the dark phase of the light dark cycle without touching the mouse. Allow the mouse to consume the agar.

After confirming the complete consumption of the agar, carefully removed the way boat from the cage and repeat as necessary. Socially isolated mice spend significantly less time in the open arm and a significantly longer time in the closed arm compared to the control group. In the open field test, socially isolated mice traveled less distance, reared less, and spent more time in the corners.

Similarly, they spent less time in the central area than the control, indicating enhanced anxiety-like behavior. Socially isolated mice also displayed reduced novel object and novel context recognition compared to control, suggesting cognitive impairment. This technique allows us to study the development of anxiety and cognitive impairment rather than just the outcome of the disorders.