Purchase this article with an account.
E. R. Ritchey, K. A. Code, S. Petersen-Jones, A. J. Fischer; Form-Deprivation and Eye Growth in the Retinopathy, Globe Enlarged (RGE) Chicken. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3935.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Retinopathy, globe enlarged (RGE) chickens develop an ocular phenotype because of a spontaneous 3 base pair mutation, D153del, of GNB3. The D153del deletion results in reduced vision in newly hatched chicks that progressively worsens over time. Concurrently, RGE chicks develop a progressive globe enlargement in the radial and axial dimensions. The purpose of this study was to investigate whether form-deprivation stimulates excessive ocular growth of early postnatal RGE chicks. In addition, we sought to test whether the glucagon-positive amacrine cells, which are known to respond to growth-modulating visual cues, behave normally in RGE retinas.
RGE chickens were hatched from fertilized eggs obtained from a cross of RGE homozygous chickens. At post-natal day 7 (P7), form-depriving goggles were applied to the right eye only of RGE chicks using cyanoacrylate adhesive. After six days, goggles were removed and chicks were given 2 hours of unrestricted vision. Chicks were sacrificed and both eyes were enucleated. Photographs of the eyes were taken with a Nikon 6 megapixel SLR camera. After photography, eyes were hemi-dissected, the vitreous removed and the anterior and posterior eye fixed in 4% paraformaldehyde. 12 micron thick sections were thaw-mounted onto Superfrost plus slides and were immunolabeled for glucagon and Egr-1. Photographs were analyzed for axial length and overall circumference using ImagePro 6.2 software.
The eyes of RGE chickens treated with form-deprivation goggles showed a significant increase in axial length, nasal-temporal diameter, dorsal-ventral diameter and overall equatorial circumference compared to the untreated contralateral eye. Glucagon-expressing amacrine cells are known to respond to growth-modulating visual stimuli by up- or down-regulating Egr1-expression. We find that Egr1 is up-regulated in glucagoneric amacrine cells in response to recovery from form-deprivation, similar to wild-type retinas.
Early post-natal RGE chickens respond to form-deprivation in a similar manner to wild type chicks. The expression of Egr-1 in form deprived eyes in these chicks indicates that glucagon-positive amacrine cells respond to growth-regulating visual stimuli.
This PDF is available to Subscribers Only