March 2012
Volume 53, Issue 14
Free
ARVO Annual Meeting Abstract  |   March 2012
More Numerous Photosensitive Ganglion Cells In A Macular Degeneration
Author Affiliations & Notes
  • Frederick R. Blodi
    Department of Pediatrics,
    University of Iowa, Iowa City, Iowa
  • Steven F. Stasheff
    Department of Pediatrics,
    Department of Ophthalmology & Visual Sciences,
    University of Iowa, Iowa City, Iowa
  • Stewart Thompson
    Department of Ophthalmology & Visual Sciences,
    University of Iowa, Iowa City, Iowa
  • Malini Shankar
    Department of Pediatrics,
    University of Iowa, Iowa City, Iowa
  • Robert F. Mullins
    Department of Ophthalmology & Visual Sciences,
    University of Iowa, Iowa City, Iowa
  • Michael P. Andrews
    Department of Pediatrics,
    University of Iowa, Iowa City, Iowa
  • Edwin M. Stone
    Department of Ophthalmology & Visual Sciences,
    University of Iowa, Iowa City, Iowa
  • Footnotes
    Commercial Relationships  Frederick R. Blodi, None; Steven F. Stasheff, None; Stewart Thompson, None; Malini Shankar, None; Robert F. Mullins, None; Michael P. Andrews, None; Edwin M. Stone, None
  • Footnotes
    Support  NIH Grant EY-016822
Investigative Ophthalmology & Visual Science March 2012, Vol.53, 4338. doi:
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      Frederick R. Blodi, Steven F. Stasheff, Stewart Thompson, Malini Shankar, Robert F. Mullins, Michael P. Andrews, Edwin M. Stone; More Numerous Photosensitive Ganglion Cells In A Macular Degeneration. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4338.

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

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Abstract

Purpose: : We sought to determine the origin of increased behavioral sensitivity to light in a mouse model of the inherited early-onset macular degenerative disease malattia leventinese (Efemp1R345W) [1]. We previously found that this mutation caused an unexpected increase in sensitivity to light for a behavior (negative masking) mediated by intrinsically photosensitive retinal ganglion cells (ipRGCs) [2]. Next, we determined that Efemp1 localizes to the retinal ganglion cell layer, and hypothesized that mutant Efemp1 was altering the light responsiveness of retinal ganglion cells. We now report an increased number of ipRGC-like responses in Efemp1R345W mice.

Methods: : We used in vitro multielectrode recording to monitor retinal ganglion cell activity in wild type (wt) and Efemp1R345W mice. Action potentials were recorded as full field broadband light flashes were presented (peak irradiance 1016-1018 photons/cm2·s at 548 nm, duration 2-25 sec) to retinas perfused with control Ringer’s solution and one designed to pharmacologically prevent all synaptic transmission, thus revealing those cells with intrinsic photosensitivity.

Results: : In wt retinas under pharmacologic blockade of synaptic transmission, typically 3-4 ganglion cells per retina were detected that had responses characteristic of ipRGCs (relatively long latency and duration). In contrast, 15-25 such cells were recorded in retinas from Efemp1R345W mice.

Conclusions: : Our recordings indicate that Efemp1R345W mutations can lead to an increase in the number of ganglion cells that exhibit intrinsic responses to light. This might be due to an overall greater number of melanopsin-containing ipRGCs in mutant retinas relative to wt. Alternatively, there may be increased signal propagation from ipRGCs to other classes of ganglion cells not normally directly responsive to light. In either case, this identifies a novel function for Efemp1 in the retina.1. Roybal, C.N., et al., Aberrant accumulation of fibulin-3 in the endoplasmic reticulum leads to activation of the unfolded protein response and VEGF expression. Investigative ophthalmology & visual science, 2005. 46(11): p. 3973-9.2. Thompson, S., et al., Selective Disruption of Non-Visual Responses to Light in a Mouse Model of Malattia Leventinese. Invest. Ophthalmol. Vis. Sci., 2009. 50(5): p. 2561.

Keywords: retinal degenerations: hereditary • ganglion cells • electrophysiology: non-clinical 
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