Restraint to Induce Stress in Mice and Rats

My research focuses on the neurobiological mechanisms impacting stress effects, the behavioral effects of drugs of abuse, and the intersection between the two. In short, my laboratory tries to answer how stress experiences contribute to substance use disorders and how we can develop interventions to address this relationship. My research has shown that stress exposure alters noradrenergic systems in a manner that persists beyond the experience of stress.

These increases in noradrenergic signaling may underscore heightened arousal responses characteristic of PTSD and other disorders. Compared to other stress inducing approaches, restraint is inexpensive, easy to perform, useful to model aspects of human disorders including anxiety, depression, substance use disorder, and post-traumatic stress disorder, and can be adapted with a wide range of parameters. In the future, my laboratory will focus on mechanisms underlying the changes in drug-induced behavior resulting from stress or exposure.

To begin, randomly assign mice to the home cage control, acute restraint stress, or chronic restraint stress groups. Determine the length of stress exposure based on the assigned group. Next, modify 50 milliliter conical tubes to create ventilation holes using a power drill with a 1/8 inch bit.

Evenly space the holes to allow airflow throughout the tube, ensuring the mouse can breathe regardless of position. In a testing room separate from animal housing and behavioral testing areas, place the assigned mouse into the modified conical tube. Attach the cap securely to confine the animal for the designated restraint period.

Then, place the restraint tube horizontally on a flat surface. If necessary, secure the tube with laboratory tape or a pipette basin to prevent it from rolling. Monitor the restrained animal every 20 minutes for unusual behaviors.

After the stress exposure, return the mouse to the home cage. Randomly assign the rat to the home cage control, acute restraint stress, or chronic restraint stress groups. For commercially available restraint tubes, insert the rat into the device, adjust the plug to fit the subject's size snugly, and lock it in place.

Ensure the rat is properly confined to prevent head to tail turns while allowing normal breathing. In a testing room separate from animal housing and behavioral testing, place the assigned rats into their restraint tubes for the designated restraint length. Position each tube horizontally on a flat surface.

After the stress session, return the rat to its home cage with free access to food and water. Plasma corticosterone concentration was significantly higher after a single stress exposure than naive controls, but this elevation was reduced in mice subjected to repeated stress. Repeated stress exposure significantly increased norepinephrine release across various optogenetic stimulation parameters.