A project led by the researchers from the University of California, San Francisco has shown that brief, acute situations of psychological stress can promote healing in mouse models for three different types of skin irritations. It has led the researchers to understand the reason of this otherwise harmful component of stress response to be preserved during the human evolution.
Scientists for the project studied mouse models for three types of common skin irritations namely irritant contact dermatitis caused by exposure to an irritant such as soap or solvent and an acute allergic contact dermatitis caused by poison ivy or poison oak and atopic dermatitis or eczema. After exposing the mice to the irritants on a small patch of skin on one ear, one group was returned to its regular cage while the other group was put under stressful conditions for 18 hours a day, over the course of four days in a very small enclosure.
The results, however, show that the stressed group had a significant reduction in inflammation and faster healing in all the three types of skin irritation. When stressed mice were administered mifepristone, which blocks the steroid action, all healing benefits of the stress disappeared, thus, demonstrating the central role of internal steroids in healing irritation. Under chronic stress, the same naturally–occurring steroids damage the protective functions of normal skin. However, during shorter intervals of stress, they are beneficial for inflammatory disorders and acute injuries in both mice and humans.
The study provides a clue to an evolutionary puzzle on why have the humans preserved the tendency to produce steroids under stress for over millions of years. Researchers state that the lack of pharmaceutical steroids back then, is the reason why natural steroids were preserved as safe, effective and with an internal anti–inflammatory system.