May 1999
Volume 40, Issue 6
Free
Articles  |   May 1999
Functional protection of photoreceptors from light-induced damage by dimethylthiourea and Ginkgo biloba extract.
Author Affiliations
  • I Ranchon
    Laboratory of Biophysics, School of Pharmacy, University of Auvergne, Clermont-Ferrand, France.
  • J M Gorrand
    Laboratory of Biophysics, School of Pharmacy, University of Auvergne, Clermont-Ferrand, France.
  • J Cluzel
    Laboratory of Biophysics, School of Pharmacy, University of Auvergne, Clermont-Ferrand, France.
  • M T Droy-Lefaix
    Laboratory of Biophysics, School of Pharmacy, University of Auvergne, Clermont-Ferrand, France.
  • M Doly
    Laboratory of Biophysics, School of Pharmacy, University of Auvergne, Clermont-Ferrand, France.
Investigative Ophthalmology & Visual Science May 1999, Vol.40, 1191-1199. doi:
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      I Ranchon, J M Gorrand, J Cluzel, M T Droy-Lefaix, M Doly; Functional protection of photoreceptors from light-induced damage by dimethylthiourea and Ginkgo biloba extract.. Invest. Ophthalmol. Vis. Sci. 1999;40(6):1191-1199.

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

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Abstract

PURPOSE: To investigate the functional protective effect of a synthetic (dimethylthiourea, DMTU) and a natural antioxidant (Ginkgo biloba extract, EGb 761) against light-induced retinal degeneration. METHODS: Wistar rats were exposed for 24 hours to 1700-lux light after treatment with DMTU or EGb 761. Electroretinograms were recorded before and on day (D)1, D3, D8, D15, D22, and D29 after light exposure. The b-wave amplitude was plotted against log L (ganzfeld luminance), providing the b-wave sensitivity curve. The Naka-Rushton function fitted to the sensitivity curve enabled derivation of the parameters Bmax (saturated amplitude) and K (luminance-inducing Bmax/2). In addition, rats from each group were killed for retinal morphometric analyses. RESULTS: In the untreated group, light exposure caused collapse of the b-wave sensitivity curves. Bmax was reduced by 51% at D1 without subsequent recovery. K increased temporarily, reverting to normal values 8 days later. The outer nuclear layer thicknesses decreased markedly in the superior retina. In the treated groups, light exposure had a weaker effect on sensitivity curves. The values of Bmax were not significantly different from those in the unexposed-untreated group, although K increased temporarily. Retinal morphometry was preserved. CONCLUSIONS: Dimethylthiourea and EGb 761 afford functional protection against light-induced retinal damage.

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