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Photoreceptor damage induced by low-intensity light: model of retinal degeneration in mammals

M. A. Contín,Milagros M. Arietti,M. M. Benedetto,Claudio Bussi,M. Guido

Published 2013 in Molecular Vision

ABSTRACT

Purpose Retinal degeneration caused by a defect in the phototransduction cascade leads to the apoptosis of photoreceptor cells, although the precise molecular mechanism is still unknown. In addition, constant low light exposure produces photoreceptor cell death through the activation of downstream phototransduction. The authors investigated the time course and molecular mechanisms of death and the rhodopsin phosphorylation occurring during retinal degeneration after exposure to continuous low-intensity light. Methods Wistar rats were exposed to constant cool white 200 lx intensity LED light (LL) for one to ten days and compared with animals kept in the dark (DD) or controls exposed to a regular 12:12 h (LD) cycle. One eye from each rat was used for histological and quantitative outer nuclear layer (ONL) analysis and the other for biochemical assays. Results The histological analysis showed a significant reduction in the ONL of LL-exposed rats after seven days compared with LD- or DD-exposed rats. Retinal analysis by flow cytometer and the TUNEL assay revealed an increase in cell death in the ONL, the in vitro enzymatic activity assay and western blot analysis showing no caspase-3 activation. The rhodopsin analysis demonstrated more phosphorylation in serine 334 residues (Ser334) in LL-exposed than in LD- or DD-exposed rats. However, for all times studied, rhodopsin was completely dephosphorylated after four days of DD treatment. Conclusions Constant light exposure for seven days produces ONL reduction by photoreceptor cell death through a capase-3-independent mechanism. Increases in rhodopsin-phospho-Ser334 levels were observed, supporting the notion that changes in the regulation of the phototransduction cascade occur during retinal degeneration.

PUBLICATION RECORD

  • Publication year

    2013

  • Venue

    Molecular Vision

  • Publication date

    2013-07-25

  • Fields of study

    Biology, Medicine, Environmental Science

  • Identifiers
    PMID 23901245PMCID 3724958
  • External record

    Open on Semantic Scholar

  • Source metadata

    Semantic Scholar, PubMed

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