Purchase this article with an account.
N. Tanimoto, F. Tonagel, S.C. Beck, S. Dangel, B. Wissinger, M.W. Seeliger; Progressive Loss of Cone Cells in Transgenic Mice With Cone–Specific GFP Expression Revealed in vivo by Retinal Confocal Imaging and ERG . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4577.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Single cells in retinal tissues can be visualized in vivo by scanning–laser ophthalmoscopy (SLO) if they express GFP (Seeliger et al., Vision Res 2005). Thus, transgenic mice expressing GFP in photoreceptors may be useful to follow the time course of a retinal degeneration in double mutants. The aim of this study was to investigate whether a transgenic line expressing GFP under control of a RG opsin promotor is suitable for such long–term assessment of cone functionality.
Transgenic mice aged 2–10 months from a line expressing GFP under control of a RG (cone) opsin promotor (Fei & Hughes, Vis Neurosci 2001) were examined in this study. A Heidelberg Engineering HRA I SLO (Heidelberg Engineering, Dossenheim, Germany) was used for the detection of cone numbers and distribution by their GFP–driven autofluorescence. In the same mice, functional testing was performed with Ganzfeld electroretinography (ERG; Jaeger/Toennies, Multiliner Vision, Hoechberg, Germany) under both scotopic and photopic conditions. The study was performed in accordance with the ARVO Statement for the Use of Animals in Ophthalmic and Visual Research.
Individual GFP–expressing cones were discernible in SLO autofluorescence mode (488 nm blue laser stimulus, barrier filter at 500 nm). There was a dense distribution across the visible part of the retina, with a slight superior–inferior gradient. The number of GFP–expressing cones and the grade of fluorescence decreased with age. At 6–7 months, there was already a marked reduction in most animals, and at 10 months, only several fluorescent spots could be detected. The ERG data correlated well with the morphological results: There was a steady decrease of cone functionality until at about 10 months, no detectable response remained in the photopic flash and flicker ERGs. In contrast, the scotopic flash and flicker ERG was normal with respect to the rod system. These ERG findings were very similar to those in the cone CNG channel deficient mice lacking any cone–mediated response (Biel et al., PNAS 1999).
The RG–GFP mouse line undergoes a progressive, selective degeneration of cone photoreceptors with age, which makes it less useful for long–term observations in double mutant mice. However, the time course of that intrinsic degeneration is rather slow so that short–term studies should not be affected.
This PDF is available to Subscribers Only