May 2007
Volume 48, Issue 13
ARVO Annual Meeting Abstract  |   May 2007
Impaired Choroidal Circulation and Delayed Loss of Cone and Remaining Rod Photoreceptor Cells Following Acute Light Exposure in Rats
Author Affiliations & Notes
  • M. Tanito
    Ophthalmology, Shimane Univ Sch of Medicine, Izumo, Japan
  • S. Kaidzu
    Ophthalmology, Shimane Univ Sch of Medicine, Izumo, Japan
  • A. Ohira
    Ophthalmology, Shimane Univ Sch of Medicine, Izumo, Japan
  • R. E. Anderson
    Ophthalmology and Cell Biology, Univ Oklahoma Health Sci Ctr, Oklahoma City, Oklahoma
    Dean McGee Eye Institute, Oklahoma City, Oklahoma
  • Footnotes
    Commercial Relationships M. Tanito, None; S. Kaidzu, None; A. Ohira, None; R.E. Anderson, None.
  • Footnotes
    Support NIH grants EY00871, EY04149, EY12190, and RR17703; Foundation Fighting Blindness, Inc.,; and Research to Prevent Blindness, Inc.
Investigative Ophthalmology & Visual Science May 2007, Vol.48, 4496. doi:
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    • Get Citation

      M. Tanito, S. Kaidzu, A. Ohira, R. E. Anderson; Impaired Choroidal Circulation and Delayed Loss of Cone and Remaining Rod Photoreceptor Cells Following Acute Light Exposure in Rats. Invest. Ophthalmol. Vis. Sci. 2007;48(13):4496.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose:: To examine the long-term effects of acute light exposure in the retina, and retinal pigment epithelial (RPE) and choroidal layers.

Methods:: Albino rats injected with either the protective antioxidant phenyl-N-tert-butylnitrone (PBN) or saline 30 min prior to exposure with 5 k lux white fluorescent light for 6 h were kept for up to 3 months. Electroretinograms were recorded and the outer nuclear layer (ONL) and the choroidal thickness were measured. The expression of rod, cone, and RPE cell-specific markers was detected by Western blotting, and apoptosis was analyzed by TUNEL staining. Oxidative stress was analyzed by immunohistochemistry of 4-hydroxynonenal (HNE)-modified proteins. Retinal and choroidal ultrastructure was observed by transmission electron microscopy. Choroidal circulation was determined by in vivo staining of the choroidal layer by trypan blue.

Results:: In saline-injected animals, TUNEL- and 4-HNE-labeling in the ONL, RPE, and choroid was greater 24 h and 7 days after light exposure, and ERG amplitudes, ONL and choroidal thickness, and the expression of rhodopsin and RPE65 were lower 7 days after light exposure and later, compared to PBN-injected animals. In saline-injected animals, the expression of mid-wavelength opsin and the presence of cone nuclei in the ONL, and the choroidal circulation were preserved 7 days after light exposure, but started to decrease by 1 month and continued to decrease for 3 months following light exposure. An increase in TUNEL-positive cells was observed in the ONL at the inferior peripheral retina just behind the iris by 3 months after light exposure. Delayed loss of cone cells and remaining rod cells, and reduction in choroidal circulation, were counteracted by PBN treatment.

Conclusions:: Although cone cells are resistant to cell damage induced by acute photo-oxidative stress, progressive slow loss of cone cells continued for up to 3 months after light exposure. Impaired choroidal circulation may be involved in the mechanism of delayed photoreceptor cell death. Therefore, preserving choroidal circulation may provide a novel target for retarding loss of cone and rod cells in patients with retinal degeneration such as retinitis pigmentosa.

Keywords: photoreceptors • choroid • oxidation/oxidative or free radical damage 

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