May 2003
Volume 44, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2003
Detailed Characterization of Electroretinographic Abnormalities in the Retinopathy, Globe Enlarged (rge) Chick
Author Affiliations & Notes
  • F.M. Ferreira
    College of Veterinary Med, Michigan State University, East Lansing, MI, United States
  • S.M. Petersen-Jones
    College of Veterinary Med, Michigan State University, East Lansing, MI, United States
  • Footnotes
    Commercial Relationships  F.M. Ferreira, None; S.M. Petersen-Jones, None.
Investigative Ophthalmology & Visual Science May 2003, Vol.44, 4534. doi:
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      F.M. Ferreira, S.M. Petersen-Jones; Detailed Characterization of Electroretinographic Abnormalities in the Retinopathy, Globe Enlarged (rge) Chick . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4534.

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

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Abstract

Abstract: : Purpose: We have previously reported that rge chicks become functionally blind by about 7 weeks post hatch and have an abnormal ERG waveform. The purpose of this study was to further characterize the ERG in this retinopathy model. Methods: Dark-adapted and and light-adapted electroretinograms were recorded using a UTAS-E 3000 (LKC) from normal (-/-), carrier (rge/-) and affected (rge/rge) chicks at 1, 7 , 14, 28 and 150 days post-hatch. Naka-Rushton function fit was applied to the b-wave data using SigmaPlot 2001, version 7.101 (SPSS, Inc), which employs a Marquardt-Levenberg algorithm to perform least-squares fits. Results: The ERGs from rge/+ and +/+ were not significantly different. Amplitude vs intensity function for both a- and b-waves shows a fairly mature form in the day-old chicks, reflecting the relative maturity of the retina at hatch in this species. There is no discernable difference between the control and rge/rge b-wave Vmax functions. A-wave sensitivity is decreased in the rge/rge birds. A-wave Vmax approximately doubles in the control group as the chick matures but does not increase in the rge/rge birds. The steepness of the slope of the a-wave is much reducued in rge/rge chicks at all ages. Conclusions: The rge/rge birds show reduced sensitivity and lack of developmental change in a-wave Vmax compared to the control groups. The similarity of effect on the sensitivity parameter in a- and b-waves suggests that the main effect of the rge mutation is on the photoreceptors themselves with effects propagated through to the bipolar cells underlying the b-wave response. This is supported by the lack of increase in a-wave Vmax with age in the rge/rge group. The reduction in sensitivity is present at the earliest age tested (at hatch), suggesting that photoreceptor dysfunction is present from hatch.

Keywords: retina • degenerations/dystrophies • genetics 
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