title: Ultraviolet B irradiation of the eye activates a nitric oxide-dependent hypothalamopituitary proopiomelanocortin pathway and modulates functions of alpha-melanocyte-stimulating hormone-responsive cells.
abstract: Ultraviolet B radiation increases DOPA-positive melanocytes in the skin specifically at the site of exposure. We found unexpectedly that ultraviolet B irradiation of the eye increased the concentration of alpha-melanocyte-stimulating hormone in plasma and systemically stimulated epidermal melanocytes in mice. To test the possible involvement of hypothalamopituitary proopiomelanocortin system in the systemic activation of skin melanocytes, ultraviolet B was also irradiated to the eye after hypophysectomy. Hypophysectomy strongly inhibited the ultraviolet B-induced stimulation of melanocytes. To elucidate the pathway by which ultraviolet B irradiation of the eye activated the hypothalamopituitary system, we examined the effect of bilateral ciliary ganglionectomy and denervation of the optic nerves on the ultraviolet B-induced melanocyte stimulation. Ciliary ganglionectomy, but not optic nerve denervation, strongly inhibited melanocyte stimulation by localized irradiation of the eye. Furthermore, melanocyte stimulation by localized ultraviolet B irradiation of the eye was not observed in mice that lack the inducible type of nitric oxide synthase. These results clearly indicate that a signal evoked by ultraviolet B irradiation of the eye is transmitted in a nitric oxide-dependent manner through the ciliary ganglia involving the first branch of the trigeminal nerve to the hypothalamopituitary proopiomelanocortin system, resulting in upregulation of alpha-melanocyte-stimulating hormone secretion and consequent stimulation of melanocytes in the skin. The novel network involving the trigeminal nerve and nitric oxide-dependent signaling pathway might play important parts in the activation of proopiomelanocortin-dependent biologic reactions, such as alpha-melanocyte-stimulating hormone-induced stimulation of melanocytes in the skin, in ultraviolet B-enriched environments.
authors.affiliation: Department of Biochemistry and Molecular Pathology, Osaka City University Medical School, 1-4-3 Asahimachi, Abeno, Osaka 545-8585, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Hiramoto
authors.forename: Nobuyo
authors.initials: N
authors.lastname: Yanagihara
authors.forename: Eisuke F
authors.initials: EF
authors.lastname: Sato
authors.forename: Masayasu
authors.initials: M
authors.lastname: Inoue
mesh_terms: D000818:Animals; D003714:Denervation; D004295:Dihydroxyphenylalanine / Q000032:analysis; D005123:Eye / Q000528:radiation effects*; D007016:Hypophysectomy; D007031:Hypothalamus / Q000502:physiology*; D008297:Male; D008544:Melanocytes / Q000528:radiation effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000502:physiology; D052247:Nitric Oxide Synthase Type II; D010902:Pituitary Gland / Q000502:physiology*; D011333:Pro-Opiomelanocortin / Q000502:physiology*; D014466:Ultraviolet Rays; D000521:alpha-MSH / Q000097:blood / Q000502:physiology*
chemical_list: D009569:Nitric Oxide; D000521:alpha-MSH; D004295:Dihydroxyphenylalanine; D011333:Pro-Opiomelanocortin; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse