| The effects of light regimes and hormones on corneal growth in vivo and in organ culture. | |
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MedLine Citation:
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PMID: 21951233 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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When chicks are exposed to constant light (CL) during growth, their corneas become flatter and lighter in weight, and their anterior segments become shallower than those of chicks exposed to cyclical periods of light and dark. These effects have been correlated with CL suppression of cyclical changes in melatonin levels. The question of whether light directly influences corneal growth (e.g. via cryptochromes in the cornea) or acts remotely via the suppression of the melatonin rhythm has not yet been answered. Retinoic acid (RA), an ubiquitous morphogen, also causes non-functional flattening during corneal growth, but its effect in vivo has not been correlated with light regimes. We wished to characterize and distinguish between hormonal and light effects on corneal growth. We used organ culture to study the direct effects of light regimes, melatonin, and RA, and compared these results with those of parallel in vivo experiments. In this study, eye drops containing melatonin or RA were applied to corneas exposed to CL in vivo or in organ culture, and effects on corneal mass and hydration were measured. We applied a melatonin blocker, luzindole, to chick corneas in normal light/dark conditions to confirm that the observed melatonin effects are mediated at the cell membrane. Anterior chamber depth and refraction in vivo were measured. We found that, during CL exposure, combined application of melatonin and RA eye drops increased the depth of the anterior segment in vivo, (P = 0.003) and interestingly, both also reduced the hyperopia of CL exposure after 2 weeks (P = 0.002), thus partially reversing the effects of CL. RA increased corneal hydration in vivo (P = 0.030) but not in organ culture. Melatonin had no effect on corneal hydration in vivo, but in organ culture, melatonin significantly decreased hydration (P < 0.001). We found no evidence for a direct effect of light on corneal hydration in growing chick corneas in culture. Melatonin is required for normal corneal growth in vivo, and together melatonin and RA, or RA alone, affects the regulation of water content within the chick cornea. Melatonin also affects corneal hydration in vitro, but RA does not. |
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Authors:
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Christina Wahl; Tong Li; Yuko Takagi; Howard Howland |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-9-26 |
Journal Detail:
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Title: Journal of anatomy Volume: - ISSN: 1469-7580 ISO Abbreviation: - Publication Date: 2011 Sep |
Date Detail:
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Created Date: 2011-9-28 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0137162 Medline TA: J Anat Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Copyright Information:
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© 2011 The Authors. Journal of Anatomy © 2011 Anatomical Society of Great Britain and Ireland. |
Affiliation:
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Department of Biological and Chemical Sciences, Wells College, Aurora, NY, USA Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, USA. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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