Effects of two chronic stresses on mental state and hair follicle melanogenesis in mice

Growing bodies of data show that psychological stress can be associated with hair loss and vitiligo. Researchers have revealed that stress could indeed inhibit hair growth in vivo, but the relationship between chronic stress and melanogenesis remains unknown. In this study, we established two types of stress models, chronic restraint stress (CRS) and chronic unpredicted mild stress (CUMS) mice models, and explored the possible role of stress in mice hair follicle melanogenesis. We found that stress changed hippocampal morphology, decreased 5‐HT level in brain and skin and down‐regulated 5‐HT1A receptor expression in hippocampal CA1 region and skin. The alterations of 5‐HT and 5‐HT1A receptor might be a threshold of central stress to associate with the behaviour changes. Both two stresses caused cellular damage of melanocytes and inhibition of keratinocytes proliferation in HF, which made the synthetic pigment loss. CRS which was considered primarily as a “psychological” stressor had the lower melanin production in HF, as well as the level of 5‐HT in skin was down‐regulated more than those in CUMS group.