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M. Marchena, J. Vicente, J. Lara, J. Aijón, R. Barhoum, P. de la Villa, A. Velasco; The Retina of Pcd Mouse as Model of Photoreceptor Degeneration Structural and Functional Study. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3716. doi: https://doi.org/.
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Under denomination of retinitis pigmentosa (RP) are included a group of retinal degenerations that lead to gradually loss of photoreceptor cells. In this work, we used the pcd (Purkinje cell degeneration) mutant mouse, a model where the loss of photoreceptors is also slow. Although the spatial and temporal patterns of photoreceptor degeneration in this model have already been described, it is not known whether the rest of neuronal populations are affected, a requisite for its use as recipient of therapeutic assays. The analysis of structural and functional modifications in these neuronal populations is the object of this work.
Structural and functional studies were performed on 6 wild type and 6 pcd/pcd mutant mice of the C57/DBA strain for each time point of the study: 45, 60, 90, 180 and 270 post-natal days. Immunohistochemical studies were done for protein markers: calbindin, calretinin, protein kinase C alpha, RT97, mGluR6, bassoon, synapsin and syntaxin. Electroretinographic recordings were performed on control and dystrophic mice. Scotopic threshold responses, oscillatory potentials, rod, and mixed responses were recorded under dark adapted conditions; cone and flicker responses were recorded under light adaptation.
Our results show few, but significant, structural modifications in the neuronal populations. Main morphological changes affect to bipolar cells, which gradually loss their dendritic tufts. The electroretinographic records reveal that, in the pcd retinas, the rod and cone system show a reduction in the amplitude of the electrical signals. This decrease progresses gently with age. Thus, in the most advanced considered stage of photoreceptor degeneration, 270 post-natal days, it is possible to record light responses. In addition, we detected changes in other parameters, such as the ability to respond to close light stimuli (flicker) and the amplitude of oscillatory potentials.
The slow loss of photoreceptor cells in the retina of pcd mice entails a good conservation of structure of the retina and a gradual decrease in the amplitude of the electrical signals in response to the light stimulus. Thus, as well as to provide data about the degenerative process itself, our results could serve as reference for evaluating the efficacy of diverse treatments against the RP.
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