Sympathetic Nerves Are Dispensable for the Responses of Melanocyte Stem Cells to Ultraviolet B Exposure

ABSTRACT Sympathetic nerves are known to regulate stem cells in the skin. In mice, acute nociception stress activates sympathetic nerves to release noradrenaline, which acts on ADRB2 receptors in melanocyte stem cells (McSCs) to regulate their activation, differentiation and migration. Similarly, ultraviolet B (UVB) exposure induces McSCs behaviours comparable to those observed under acute stress. While epidermal keratinocytes are recognised as key regulators of McSCs responses through secreted factors encoded by genes such as Wnt7a, Col2a1 and Pomc during UVB exposure, the role of other niche components remains largely unexplored. In this study, we investigated whether sympathetic nerves influence McSCs responses to UVB exposure. Using 6‐hydroxydopamine to ablate sympathetic nerves, we found no significant differences in McSCs migration, differentiation, or the expression of key keratinocyte‐secreted factors between control and sympathetically denervated mice. Furthermore, beta‐adrenergic receptor blockade with Nadolol did not affect McSCs responses to UVB. These findings suggest that sympathetic nerves are dispensable for the responses of McSCs to UVB exposure.