Photoreceptor Apoptosis And Fas, Bcl-2 Expression In Inherited Retinal Degeneration

Objective To investigate photoreceptor (PRC) apoptosis and gene regulation in hereditary retinal degeneration of Royal College of Surgeon (RCS) rats.Methods The retinal sections of RCS and SD rats in different ages were examined by hematoxylin and eosin staining, TdT-mediated dUTP nick-end labeling (TUNEL) and Bcl-2, Fas protein immunohistochemical method.Results (1) Hematoxylin and eosin staining. Compared with age matched SD rats, the rod layer became thicker at 15 days of age, the place where were near the RPE became misalighed and formed vacuolation. The width of the rod layer reached the peak stage at 25 days of age. The number of PRC in RCS rats reduced at 20 days of age. At 60 days of age, only a few PRC remained. Postnatal 30 to 40 days was the peak stage of PRC death.(2) TUNEL: The nuclei of PRC in RCS rats were stained positively by TUNEL after being born for 25 days, the positive labeled nuclei could be determined only in the outer nuclear layer, reached the highest level at 35 days of age. The positive staining reached the peak stage in the optical density at 35days of age.(3) Fas protein immunohistocehmical labeling: Positive staining of Fas protein could be seen in the inner nuclear layer of RCS rats at 15 days of age and showed the most at 25 days of age, the stainedgranules of Fas protein in the inner nuclear layer reached the peak stage in the mean optical density at 25 days of age. The positive staining could be seen in the outer nuclear layer at 25, 30 , 35 and 40 days of age. The stained granules could also be seen in the layer of ganglion cells at 15 days of age and lasted until 40 days of age. No obvious positive labeling could be seen at 60 days of age.(4) Bcl-2 protein immunohistichemical labeling: From 25-40 days of age, only a few positive granules could be detected in the layer of ganglion cells. The positive staining could be seen in the inner nuclear layer from 25 days of age and reached the peak stage at 35 days of age. No obvious positive granules could be detected in the outer nuclear layer at all ages.Conclusion It is through apoptosis that the retinal PRC died inretinal degeneration of RCS rats. Apoptosis of PRC in RCS rats mightbe Fas-dependent and might have little relationship with Bcl-2 protein.