How the Stress of Fight or Flight Turns Hair White

The study by Zhang et al. revealed that stress-induced hair greying in mice is caused by the depletion of melanocyte stem cells (MeSCs) in hair follicles due to the release of noradrenaline from sympathetic neurons, rather than from corticosterone or autoimmune reactions. The researchers subjected mice to various stressors, which led to the depletion of MeSCs and the development of white hair patches. They found that MeSCs express B₂-adrenergic receptors that respond to noradrenaline, a neurotransmitter involved in the fight or flight response. Blocking these receptors or ablating the sympathetic nervous system prevented stress-induced greying. The study also showed that overactivation of the sympathetic nervous system alone could cause greying without stress. This research suggests that stress-induced greying is not due to aging or immune response but is a direct result of sympathetic nervous system activity, raising questions about the effects of stress on other stem cell pools and potential anti-greying therapies.