Document Detail

Age-dependent control of lens growth by hypoxia.
MedLine Citation:
PMID:  18326726     Owner:  NLM     Status:  MEDLINE    
PURPOSE: The lens grows continuously throughout life, but the factors that influence the size of the adult lens are not known. Lens thickness is a significant risk factor for age-related cataract. It has been postulated that the hypoxic environment in the eye protects the lens from nuclear cataracts. The authors sought to determine whether the Po(2) in the eye regulates lens growth.
METHODS: Lens cell proliferation was determined by counting BrdU-labeled and total nuclei in the germinative zone in flatmounts of lens epithelia. Oxygen levels in the eye were altered by having rats breathe 11%, 21% (room air), or 60% oxygen. Oxygen levels in the vitreous were measured with a fiberoptic oxygen sensor.
RESULTS: The BrdU-labeling index in the germinative zone declined from approximately 3.5% at 1 month to less than 0.7% at 8 months. Raising oxygen levels in the eyes of 1-month-old animals did not alter the rate of lens cell proliferation. Elevating intraocular oxygen in animals older than 1 month increased proliferation to the more rapid rate seen at 1 month. Decreasing oxygen levels below their normally low level did not affect the BrdU-labeling index at any age. Chronic exposure to increased oxygen led to the production of more lens fiber cells and larger lenses.
CONCLUSIONS: Normal age-related decline in lens growth requires the low oxygen level normally present in the eye. Increases in lens cell number and mass may account for some of the increase in cataract risk caused by chronic exposure of the lens to elevated oxygen levels.
Ying-Bo Shui; David C Beebe
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Investigative ophthalmology & visual science     Volume:  49     ISSN:  0146-0404     ISO Abbreviation:  Invest. Ophthalmol. Vis. Sci.     Publication Date:  2008 Mar 
Date Detail:
Created Date:  2008-03-10     Completed Date:  2008-04-15     Revised Date:  2014-09-15    
Medline Journal Info:
Nlm Unique ID:  7703701     Medline TA:  Invest Ophthalmol Vis Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1023-9     Citation Subset:  IM    
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MeSH Terms
Aging / physiology*
Animals, Newborn
Anoxia / metabolism*
Bromodeoxyuridine / metabolism
Cell Count
Cell Proliferation*
Epithelial Cells / cytology*,  metabolism
Hyperoxia / metabolism
In Situ Nick-End Labeling
Lens, Crystalline / cytology,  growth & development*,  metabolism
Organ Size
Oxygen / toxicity
Grant Support
EY015863/EY/NEI NIH HHS; EY04853/EY/NEI NIH HHS; P30 EY02687/EY/NEI NIH HHS; R01 EY004853/EY/NEI NIH HHS; R01 EY004853-25/EY/NEI NIH HHS; R01 EY015863/EY/NEI NIH HHS; R01 EY015863-03/EY/NEI NIH HHS
Reg. No./Substance:
G34N38R2N1/Bromodeoxyuridine; S88TT14065/Oxygen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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