April 2011
Volume 52, Issue 14
Free
ARVO Annual Meeting Abstract  |   April 2011
Changes in Egr-1 Expression in the Guinea Pig Retina in Response to Negative Lens-wear
Author Affiliations & Notes
  • Regan S. Ashby
    ARC Centre of Excellence in Vision Sci, Australian National University, Canberra, Australia
  • Guang Zeng
    Faculty of Science and Information Technology, University of Newcastle, Newcastle, Australia
  • Amelia Leotta
    Faculty of Science and Information Technology, University of Newcastle, Newcastle, Australia
  • Sally A. McFadden, V
    Faculty of Science and Information Technology, University of Newcastle, Newcastle, Australia
  • Footnotes
    Commercial Relationships  Regan S. Ashby, None; Guang Zeng, None; Amelia Leotta, None; Sally A. McFadden, V, None
  • Footnotes
    Support  Australian Research Council Centre of Excellence in Vision Science (COE561903), CG120160 DIISR (Australian Government)
Investigative Ophthalmology & Visual Science April 2011, Vol.52, 3925. doi:
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      Regan S. Ashby, Guang Zeng, Amelia Leotta, Sally A. McFadden, V; Changes in Egr-1 Expression in the Guinea Pig Retina in Response to Negative Lens-wear. Invest. Ophthalmol. Vis. Sci. 2011;52(14):3925.

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

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Abstract

Purpose: : In chicks, alterations in the retinal mRNA expression of the immediate early gene Egr-1 is amongst the earliest known molecular changes observed in response to optically induced modulation of eye growth. This study investigated whether alterations in retinal Egr-1 mRNA levels are also observed in a mammalian model (guinea pig) in response to longer-term exposure to minus lens-wear, and recovery from such lens-wear.

Methods: : Four day-old guinea pigs were treated for 6 days with -5D lenses, before retinal tissue was collected. For recovery experiments, retinal tissue was collected following 3 days of lens removal. Changes in Egr-1 mRNA levels were determined by RT-PCR. Primers were designed through sequence alignment of the human, mouse and rat (closest phylogenetic relative) Egr-1 gene. Product specificity was validated through melt curve analysis, gel electrophoresis and automated sequencing. For immunolabelling, tissue was fixed in 4% paraformaldehyde for 1hr, and primary labelled overnight.

Results: : Following 6 days of -5D lens-wear (difference; -7.4D), Egr-1 mRNA levels in the retina were significantly down-regulated (~2 fold) in comparison to contralateral control or age-matched untreated values. In contrast, following 3 days of recovery from -5D lenses (difference; -0.5D) retinal Egr-1 mRNA levels were significantly elevated (~2-fold) compared to contralateral control or age-matched untreated values. Preliminary immunolabelling data suggest that Egr-1 is expressed in a specific subset of ganglion and amacrine cells, and also in the synaptic terminals of bipolar cells.

Conclusions: : As observed in chicks, Egr-1 mRNA levels in a mammalian retina show a bi-directional response to opposing growth stimuli, with mRNA levels down-regulated in response to negative lens-wear (growth stimulating) and up-regulated in response to recovery from negative lens-wear (growth suppressing). Changes in Egr-1 mRNA levels in response to longer periods of optical defocus may therefore be a general signal for the direction of ocular growth in all species.

Keywords: myopia • retina • emmetropization 
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