Abstract
Purpose: :
The goal of this study was to investigate structural changes and expression of different cell markers in the retinas of two different rat models, P23H and S334ter, homologous for human autosomal dominant retinitis pigmentosa.
Methods: :
Retinas from heterozygous P23H-1 and S334ter-3, and CD rats were collected at various postnatal ages (PN0 - PN30). Tissues were examined by conventional histological techniques and immunostained with cell-type-specific markers.
Results: :
Histological examination revealed the rapid and continuous retinal degeneration of S334ter-3 and the comparatively slower degeneration in P23H-1 rats. The S334ter-3 retina does not reach a normal postnatal development, as evident by rhodopsin staining, that no outer segments (OS) of photoreceptors are present at any stage of development. At PN30, rhodopsin staining showed no remaining rods, therefore, we can confirm that only cones are present in the ONL at this age. In the P23H-1 mutants, however, fully developed OS were present before degeneration began. In both models, expression of calretinin in amacrine and ganglion cells was not modified compared with CD retinae. In both mutants staining of rod-bipolar and amacrine cells by PKC was similar to CD rats but the staining intensity of their axons within the IPL was decreased at PN30. PKC labelling of S-cones in S334ter-3 animals was detected only between PN10 and 12 and then disappeared. In P23H-1 rats this staining was still present at PN30 but the OS appeared shorter than in CD retinas. Even though the number of photoreceptors was reduced, the pattern of bipolar cells expressing recoverin was unchanged in both mutants. An increased Glutamine synthetase expression, restricted to Müller cells, was apparent in both the S334ter-3 and P23H-1 retinas. Moreover, an upregulation of glial fibrillary acidic protein was observed in both transgenic rat models.
Conclusions: :
At least until PN30, the development of the inner retina is not profoundly altered in both transgenic models. S334ter-3 and P23H-1 rats are valuable tools to test potential treatments for early and late forms of RP.
Keywords: photoreceptors • retinal degenerations: cell biology • immunohistochemistry