| To investigate the morphology and distribution of melanopsin-containing retinal ganglion cells in retinal dystrophic RCS rats during retinal degeneration.
METHODS
1. Retinal dystrophic RCS rats and non-dystrophic RCS rats aged postnatal 21 days (P21d) and P60d were used for this study. Whole-mounting retina, frozen and paraffin sections were prepared for immunohistochemistry staining with anti-melanopsin antibody.
2. The retina of P21d and P60d retinal dystrophic and control RCS rats were dissected and western-blot was adopted to detect protein expression of melanopsin during different postnatal stages.
RESULTS
1. Immunohistochemistry staining showed anti-melanopsin antibody positive in about 2% RGCs in non-retinal dystrophic RCS rats and theses cells distributed in whole retina. There were not differences between retinal dystrophic and control RCS rats at P21d. But at P60d the number of melanopsin-positive RGCs reduced significantly in retinal dystrophic RCS rats.
2. Western-blot showed melanopsin expression was very weak in rats retina. The strap of 60kd protein appeared clearly in both control RCS rats and P21d retinal dystrophic RCS rats. But this strap was nearly invisible in P60d retinal dystrophic RCS rats, indicating melanopsin protein expression descreased dramaticly.
CONCLUSION
The expression of melanopsin protein decreased significantly at the late stage of retinal degeneration, and the number of melanopsin-containing RGCs disappeared following photoreceptors loss, suggesting that the functional protein expression in neural retina was impaired severely following photoreceptors loss at late stage of retinal degeneration.
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