What’s the difference between chronic stress and a bit of stress?

Chronic stress causes longer term damage, and in another study looking at social function, we gave the same amount of the same stressor to rats who don’t like to be held in place. That was an acute stressor. Then, they were paired with a smell. One was a mint smell, which was a moderate stressor. The other was a fox urine smell, which mimics that of a predator. So for both, while the rats were held in place for both for the same amount of time, the brain of the rats with the mint smell generated more oxytocin, a hormone, and its receptor. The animals became much more prosocial, cuddling with each other and playing with each other, and in doing so, they buffered their stress response. However, for the fox urine rats, there is a decrease in the oxytocin receptor and an increase in social withdrawal and aggressive behavior. The stress response is much bigger and much more damaging for the brain.