Objective: To determine whether the endoplasmic reticulum stress participates into the apoptosis process of the retina during experimental retinal detachment-by detecting the level of mRNA and protein of the GADD153, the marker of endoplasmic reticulum stress.
Methods: Completely random design is applied. Experimental retinal detachment was created in the left eyes of 77 wistar rats by injecting hyaluronic acid into the subretinal space. Rats were sacrificed at 1/2 d, 1 d, 2 d, 4 d, 8 d, 16 d and 32 d after creation of retinal detachment. Apoptosis of retinal cells was detected by TdT-mediated fluorescein-16-dUTP nick-end labeling (TUNEL) assay. GADD153 mRNA expression in the retina was determined using semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). The GADD153 protein expression was determined using western blotting. Retinal sections were studied by immunofluorescence labeling and confocal microscopy. The SPSS 10.0 software was applied to analyze data; Kruskal wallis test was applied to analyze the data about the apoptotic rate of retinal cells and the expression of GADD153 mRNA; One-way ANOVA test was applied to analyze the data about expression of GADD153 protein. P < 0.05 represents statistically significant difference.
Results: TUNEL positive staining cells were mainly presented in photoreceptor cell layer, peaked at 24 days and markedly decreased at 8 days after retinal detachment. The difference of apoptotic retinal cell rate between groups is significant (chi2 = 22.423, P < 0.05); The expression of retinal GADD153 mRNA was significantly increased at 1/2 d, 1 d, 2 d, 4 d after retinal detachment (chi2 = 27.223, P < 0.05); The expression of retinal GADD153 protein was significantly increased at these days (F = 16.052, P < 0.05). GADD153-positive cells were located in the photoreceptor cell layer.
Conclusions: GADD153, the maker of endoplasmic reticulum stress mediated apoptosis, is activated and over-expressed, associated with the occurrence of apoptosis during retinal detachment. Endoplasmic reticulum stress participates into the apoptosis process during retinal detachment.