Hair Color Change Induced By Chronic Stress And Its Mechanism

Nowadays, with the development of the society and accelerating pace of people's life, the pressure people suffering is also increasing. Stress has become inevitable in people's daily life. When suffering stress from environment or within the body, the organism can response to it and several changes also happen. Although appropriate responses can help the body fight with outside changes, hypercorrections can cause endocrine disorders or even diseases.A legend in China that a senior official named Zi-Xu Wu crossed the border and his hair turned white overnight, describes a phenomenon that stress can induce hair color change. Modern observations and social surveys also show there may be some associations between stress and hair color. However, there is no experimental evidence so far.To investigate the relationship between chronic stress and hair color and its mechanisms, we carried out our experiments from the following three aspects:Experimental design:1. C57BL/6 mice were used to suffer electric foot shock and restraint stress every day for 90 days to build animal model. In the process; hair color was observed to investigate the relationship between chronic stress and hair color; 2. Melanogenesis related markers including skin melanin content, tyrosinase activity and follicle melanocytes were detected to investigate the effects of chronic stress on melanogenesis; 3. To investigate inflammatory mechanisms behind this phenomenon, first of all, inflammatory cells infiltration, the state of NF-?B cell signaling pathway, and IL-1?, IL-6, TNF-? contents in mice skin were detected; Then, mediums containing different concentrations of TNF-a were used for B16F10 melanoma cells culture. The effects of TNF-a on melanogenesis were detected.Results:1. After suffering 90 days of chronic stress, mice's hair color turned from dark to brown; 2. In mice, skin melanin content and tyrosinase activity decresed accompany with the decreased of follicular melanocytes quantity. Simultaneously, intermittent black patches could be observed in mice epidermis; 3. In mice skin, NF-?B cell signalling pathway was activated. IL-1? and IL-6 contents showed increasing tendency but without statistical significance, however, TNF-? increased significantly. In both groups, no typical inflammatory cell was found in mice skin.Conclusions:On the one hand, after mice sufferring chronic stress, skin's NF-?B cell signalling pathway was activated accompany with the increase of TNF-? level. The increase of TNF-a level suppress the activity of tyrosinase activity. As the key enzyme for melanogenesis, the decrease of tyrosinase activity can suppress melanogenesis of mice's follicular melanocyte. Thus induce hair color change in mice. On the other hand, after mice sufferring chronic stress, follicular melanocyte stem cells may migrant from hair follicles to epiderm, this induce the decrease of follicular melanocytes and melanogenesis, thus induce hair color change in mice.This study demonstrated the relation between chronic stress and hair color, and partially clarified the mechanisms behind this phenomenon. These findings infer the potential insight into the prevention and treatment of this disease.