Protective effects of melatonin in experimental free radical-related ocular diseases

Andrew W. Siu, Maria Maldonado, Marina Sanchez-Hidalgo, Dun Xian Tan, Russel J Reiter

Research output: Contribution to journalArticle

127 Citations (Scopus)

Abstract

Melatonin (N-acetyl-5-methoxytryptamine) is an indoleamine with a range of antioxidative properties. Melatonin is endogenously produced in the eye and in other organs. Current evidence suggests that melatonin may act as a protective agent in ocular conditions such as photo-keratitis, cataract, glaucoma, retinopathy of prematurity and ischemia/reperfusion injury. These diseases are sight-threatening and they currently remain, for the most part, untreatable. The pathogenesis of these conditions is not entirely clear but oxidative stress has been proposed as one of the causative factors. Elevated levels of various reactive oxygen and nitrogen species have been identified in diseased ocular structures. These reactants damage the structure and deplete the eye of natural defense systems, such as the antioxidant, reduced glutathione, and the antioxidant enzyme superoxide dismutase. Oxidative damage in the eye leads to apoptotic degeneration of retinal neurons and fluid accumulation. Retinal degeneration decreases visual sensitivity and even a small change in the fluid content of the cornea and crystalline lens is sufficient to disrupt ocular transparency. In the eye, melatonin is produced in the retina and in the ciliary body. Continuous regeneration of melatonin in the eye offers a frontier antioxidative defense for both the anterior and posterior eye. However, melatonin production is minimal in newborns and its production gradually wanes in aging individuals as indicated by the large drop in circulating blood concentrations of the indoleamine. These individuals are possibly at risk of contracting degenerative eye diseases that are free radical-based. Supplementation with melatonin, a potent antioxidant, in especially the aged population should be considered as a prophylaxis to preserve visual functions. It may benefit many individuals worldwide, especially in countries where access to medical facilities is limited.

Original languageEnglish (US)
Pages (from-to)101-109
Number of pages9
JournalJournal of Pineal Research
Volume40
Issue number2
DOIs
StatePublished - Mar 2006

Fingerprint

Eye Diseases
Melatonin
Free Radicals
Antioxidants
5-Methoxytryptamine
Retinal Neurons
Reactive Nitrogen Species
Protective Agents
Retinopathy of Prematurity
Retinal Degeneration
Crystalline Lens
Ciliary Body
Keratitis
Reperfusion Injury
Glaucoma
Cornea
Cataract
Superoxide Dismutase
Glutathione
Retina

Keywords

  • Antioxidant
  • Cataract
  • Ischemia/reperfusion
  • Keratitis
  • Melatonin
  • Retinopathy

ASJC Scopus subject areas

  • Endocrinology

Cite this

Protective effects of melatonin in experimental free radical-related ocular diseases. / Siu, Andrew W.; Maldonado, Maria; Sanchez-Hidalgo, Marina; Tan, Dun Xian; Reiter, Russel J.

In: Journal of Pineal Research, Vol. 40, No. 2, 03.2006, p. 101-109.

Research output: Contribution to journalArticle

Siu, Andrew W. ; Maldonado, Maria ; Sanchez-Hidalgo, Marina ; Tan, Dun Xian ; Reiter, Russel J. / Protective effects of melatonin in experimental free radical-related ocular diseases. In: Journal of Pineal Research. 2006 ; Vol. 40, No. 2. pp. 101-109.
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