Ultraviolet B radiation to the eye induces pigmentation in the epidermis via the activation of the subunit gp91 phox of reduced nicotinamide adenine dinucleotide phosphate oxidase.

Irradiation by ultraviolet (UV)B is known to increase the number of dopamine (Dopa)-positive melanocytes in the skin. In this study, a 2.5-kJ/m(2) dose of UVB radiation was delivered by a sunlamp to the ear or the eye of wild-type C57BL/6j mice and of gp91 phox(-/-) C57BL/6j mice that had a knockout mutation of the gp91 phox subunit of reduced nicotinamide adenine dinucleotide phosphate oxidase (NADPH). The degree of change in the Dopa-positive melanocyte expression in was reduced in gp91 phox(-/-) mice given UVB irradiation to the eye, but not in those given irradiation to the ear. The plasma level of α-melanocyte-stimulating hormone (α-MSH) in the blood increased in the C57BL/6j mice after irradiation to either the eye or the ear, but it did not increase in the gp91 phox(-/-) mice given UVB irradiation to the eye. Both gp91 phox and α-MSH in the central nervous system seem to contribute to pigmentation after UVB irradiation of the eye in mice.