Ultraviolet B irradiation of the eye activates a nitric oxide-dependent hypothalamopituitary proopiomelanocortin pathway and modulates functions of alpha-melanocyte-stimulating hormone-responsive cells

J Invest Dermatol. 2003 Jan;120(1):123-7. doi: 10.1046/j.1523-1747.2003.12004.x.

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.

MeSH terms

  • Animals
  • Denervation
  • Dihydroxyphenylalanine / analysis
  • Eye / radiation effects*
  • Hypophysectomy
  • Hypothalamus / physiology*
  • Male
  • Melanocytes / radiation effects*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Inbred DBA
  • Nitric Oxide / physiology*
  • Nitric Oxide Synthase / physiology
  • Nitric Oxide Synthase Type II
  • Pituitary Gland / physiology*
  • Pro-Opiomelanocortin / physiology*
  • Ultraviolet Rays*
  • alpha-MSH / blood
  • alpha-MSH / physiology*

Substances

  • Nitric Oxide
  • alpha-MSH
  • Dihydroxyphenylalanine
  • Pro-Opiomelanocortin
  • Nitric Oxide Synthase
  • Nitric Oxide Synthase Type II
  • Nos2 protein, mouse