Objective To demonstrate if apoptosis is one of the mechanisms of siderotic retinopathy. Methods Autoclaved iron particles were implanted in the vitreous cavities of 32 eyes of SD rats.Glass chips were implanted in 10 control eyes.The experimental eyes were enucleated at various time intervals from days 1 to 15.Retinal degeneration was examined using the TdT-mediated,dUTP-biotin nickend labeling(TUNEL)method.Electrophoresis on agarose gel was used to detect internucleosomal DNA fragmentation.Results TUNEL-positive nuclei were observed only in the outer nuclear layer beginning on day 2.The nuclei spread throughout the outer nuclear layer by the end of day 3.No TUNEL-positive nuclei were observed in other layers throughout the experimental perios.Analysis of DNA,extracted from the retinas by electrophoresis on agarose gel,revealed a typical ladder pattern of internucleosoma DNA cleavage in the experimental eyes.ConclusionApoptosis of photoreceptors occurs at the early phase of iron-induced retinopathy in the rats.
Objective
To study on the ultrastructural characteristic of segments of photoreceptors from neonatal retinas for supporting donor retina choice of retinal transplantation．
Methods
Photoreceptors from neonatal calf and adult calf were analysed by scanning electron microscopy and transmission electron microscopy．
Results
Segments of photoreceptors from neonatal calf appeared the mushroom pattern, in which, distal end of outer segment which was ball-shaped formed the head with mushrooms appearance, and the inner segments along with some of outer segments formed the body with mushrooms appearance． Within the outer segment, plasma membranes of adjacent evaginations form a disk subsequently． The a rray of most disks were vertical to the entire length of segments, but some were parallel and slope to．Owing to the incomplete formation, some rim of disk near distal end of outer segment revealed step-shaped appearance． The distal end of outer segment displays some processes consisted of membranous discs, much vesicular material and mitochondria, much rough endoplasmic reticulum (RER) and numerous polyso mes．Segments of photoreceptor connected with outer nuclear layer via the external limiting membrane．
Conclusion
The typical morphol ogical structures of outer segments suggest the immature and b gowth ability of photoreceptors of the retina of neonatal calf, and therefore the competence for donor material of retinal transplantation．
(Chin J Ocul Fundus Dis, 2001,227-229)
Objective To investigate the protective effect of recombinant erythropoietin (EPO) on the photoreceptor cells in rat with retinal detachment (RD).Methods One hundred and sixtytwo normal male rats were randomly divided into normal control (NC) group, RD model group, RD+phosphate buffer solution （RD+PBS） group, RD+EPO 100 ng group, RD+EPO 200 ng group and RD+EPO 400 ng group. Three days after RD, activated caspase3 and bclXL were detected by Western blot and/or immunofluorescence, and apoptosis were measured by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate digoxigenin nick-end labeling（TUNEL）. Fourteen and 28 days and two months after RD, the outer nuclear layer （ONL）thickness was measured by histopathologic method.Results Western bolt indicated that the protein level of activated caspase-3 and bcl-XL between six groups were statistically significant（F=35.96, 30.75；P＜0.01）. The number of TUNEL positive cells and activated caspase-3 positive cells are consistent with each other in different groups. Fourteen days and two months after RD，the differences of ONL thickness between six groups were statistically significant（F=21.52，96.25；P＜0.01）.Conclusion Supplement of EPO after RD can alleviate apoptosis by inhibiting of the caspase-3 activity and increasing the expression of bcl-XL,thus exerts protective effect on photoreceptor cells.
Objective
To observe the changes of electrophysio logical results in rabbits with normal and injured photoreceptor due to subretinal implantation of chip.
Methods
Photoreceptor damage was induced by injection with NaIO3 solution in 22 out of 30 rabbits. A chip with the diameter of 3 mm made by the array composed of 90 microelectrodes photodiode and conjoint electrode was implanted into subretinal space or choroid of the right eyes of 22 rabbits with photoreceptor and 4 normal rabbits, and the left eyes were the control. The examinations of local flash-visual evoked potential (F-VEP), local flash-electroretinogram (F-ERG), full-field F-ERG and full-filed F-VEP were measured respectively.Another 4 rabbits underwent biocular extirpation for path ological examination .
Results
In 22 rabbits with photo-receptor damage, the amplitude of the main wave of local ERG was obviously higher in 11 eyes with chips than that in the control ones, and was also higher in 2 eyes with chips of the 4 mormal rabbits than that in the control eyes. No wave was found in an eye with retinal hole on the surface of the chip. The repeataility of main amplitude of local-VEP and full-field F-VEP is not satisfactory; no significant changes were observed between chip-implanted eyes and the control eyes examined by full-filed F-ERG.
Conclusion
The implanted chip may stimulate local retina and induce electrical activities after stimulated by light.
(Chin J Ocul Fundus DIs, 2006, 22: 324-327)
Photoreceptor cells are special retinal neurons with photo-transformation ability. Loss of photoreceptors in age-related macular degeneration (AMD) is secondary to RPE loss, leakage of serum components from the neovascularization and scar formation, which is one of the main mechanisms of irreversible visual impairment in patients with AMD. Many studies have shown that inflammatory environment is involved in the process of photoreceptor cell death. Aging, photooxidation injury and other factors affects the retinal microenvironment through different levels of mechanisms such as retinal pigment epithelial cells, retinal glial cells, hematogenous macrophages and inflammatory factors, which results in photoreceptor injuries and participates in the progression of AMD by drusen formation and neovascularization. This study reviews the research status and progress of inflammation and photoreceptor cell death, and provides new ideas for exploring the blinding mechanism and treatment strategies of AMD.
ObjectiveTo analyze the early changes of gene expression levels and signaling pathways in 661W cell line under hypoxic conditions and to find potential functional target genes.MethodsThe cultured mouse 661W cells were divided into hypoxia treatment group and normoxia control group. Cells in the hypoxia treatment group were cultured in a three-gas incubator with volume fraction of 1% and 5% CO2 at 37 ℃. Cells in the normoxia control group were cultured in an incubator at 37 ℃ with volume fraction of 5% CO2. High-throughput sequencing technology was used to sequence the transcriptome of 661W cell treated with hypoxia and normoxia for 4 hours to screen for differentially expressed genes (DEG). Clustering heat map analysis, gene ontology (GO) functional enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis and protein-protein interaction network (PPI) analysis were performed. The reverse transcription-polymerase chain reaction (RT-PCR) was used to verify the accuracy of the sequencing results.ResultsA total of 506 differentially expressed genes were screened, including 459 up-regulated genes and 47 down-regulated genes. GO functional enrichment analysis showed that the main biological processes of DEG were the cell's response to hypoxia, glycolysis, negative regulation of cell proliferation and apoptosis. hypoxia inducible factor (HIF)-1α pathway, glycolysis, Forkhead box O (FoxO) pathway, Insulin signaling pathway and Adenosine 5'-monophosphate-activated protein kinase (AMPK) pathway were involved in the above process. PPI analysis results showed that hub genes related to hypoxia were Aldoa, Aldoc, Gpi1, Hk2, Hk1, Pfkl, Pfkp, Vhl, Fbxo10 and Fbxo27. The RT-PCR results showed that the relative expression levels of 15 DEG mRNA in the hypoxic treatment group were higher than that of the normoxic control group, and the difference was statistically significant (P＜0.05). The mRNA expression levels of N-myc downstream-regulated gene-1 (Ndrg1), Mt1, and vascular endothelial growth factor A (VEGFA) were time-dependent on hypoxia.ConclusionsUnder hypoxia, DEG is mainly related to glucose metabolism, cell response to hypoxia, regulation of proliferation and apoptosis. HIF-1α pathway, glycolysis, FoxO pathway and AMPK pathway are involved in the early changes of 661W cells under hypoxia. Aldoa, Aldoc, Gpi1, Hk2, Hk1, Pfkl, Pfkp, Vhl, Fbxo10, Fbxo27 may play key roles in the response of 661W cells to hypoxia. Ndrg1, Mt1 and VEGFA could be potential functional target genes for the study of ischemia and hypoxia-related fundus diseases.
Objective
To investigate the apoptosis of photoreceptor cells in experimental model of retinal detachment in mice.
Methods
Thirty-six adult C57Bl/6J mice were divided into 2 groups: retinal detachment model was set up in the left eyes of 18 mice by subretinal injection with 1.4% sodium hyaluronate in the experimental group, while the left eyes of other 18 mice underwent scleral puncture only as the control. The retinal sections were stained with histochemical and immunofluorescent staining and examined by confocal microscopy 1,3,7 and 28 days after injection. eye enucleated, and retinal sections studied by histochemistry, immunofluorescence labeling, and confocal microscopy. Rods, cones, and apoptotic cells were labeled by antibodies of anti-rod and anti-cone cells, and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL), respectively. Photoreceptor cell apoptosis and cell loss were assessed quantitatively by counting both surviving and apoptotic rod and cone cells.
Results
TUNEL-positive cells were only found in the outer nuclear layer (ONL) of the detached portion of the retina, which were detected at the 1st day after the detachment. The apoptosis of the cells reached the peak at the 3rd day and decreased sharply after 7 days. Photoreceptor cell loss of both rod and cone cells followed a similar time course after retinal detachment.
Conclusion
Apoptosis is a major pathological degeneration of photoreceptor cell death after retinal detachment.
(Chin J Ocul Fundus Dis, 2006, 22: 124-127)
PURPOSE:To examine the role of apoptosis in photoreceptor cells degeneration process in Pathologic myopia.
METHODS: Nine human eyes with pathologic myopia were studied by
histopathologic and TDT-mediated biotin-dUTP nick-end labelling (TUNEL) techniques.
RESULT:The characteristic DNA fragmentation of apoptosis was observed in scattered photoreceptor cells in 4 of 9 eyes.
CONCLUSION:The results suggested that apoptosis is one of the pathways of photoreceptor cells death in retinal degeneration of pathologic myopia.
（Chin J Ocul Fundus Dis,1996,12: 144-146 ）
ObjectiveTo observe the morphological characteristics of photoreceptor necroptosis in experimental retinal detachment, and explore the mechanism.
MethodsA total of 60 Sprague-Dawley male rats were included in this study. Retinal detachment were induced in the right eyes with 1% sodium hyaluronate (50 μl) injection (experimental group), while the left eyes received no treatment (control group). At 3 days after modeling, the morphological characteristics of photoreceptor cell were observed by electron microscopy. Cleaved Caspase 8 and phosphorylation receptor-interacting protein 1 (p-RIP1) were measured by Western blot and immunoprecipitation.
ResultsAt 3 days after modeling, photoreceptor necroptosis showed the following morphological features: chromatin condensation, severe vacuolation, early loss of plasma membrane integrity, and many autophagosomes. Western blot showed that the protein expression of cleaved Caspase 8 were 0.78±0.03, 0.06±0.01 in experimental group and control group respectively, which was significantly different (F=4 023.21, P < 0.05). Immunoprecipitation showed that the protein expression of p-RIP1 were 0.23±0.03, 0.14±0.02 in experimental group and control group respectively, which was significantly different (F=56.44, P < 0.05).
ConclusionsPhotoreceptor necroptosis showed chromatin condensation, severe vacuolation, early loss of plasma membrane integrity, and many autophagosomes. Necroptosis activation was associated with the increase of RIP1 phosphorylation.
Objective To analyze the thickness of peripapillary retinal nerve fiber layer (pRNFL) and photoreceptor (PR) sublayer in Leber hereditary optic neuropathy (LHON) and G11778A mutation carriers. MethodsA cross sectional study. From September 2020 to October 2021, 68 LHON patients (136 eyes) (patient group) and 40 G11778A mutation carriers (80 eyes) of LHON patients' families (carrier group) were included in the study. All patients were found to have G11778A mutation by Genetic testing. Forty healthy volunteers with 80 eyes matched to the age and gender of the patient group were recruited as a normal control group. All eyes were examined by optical coherence tomography (OCT). The pRNFL thickness was automatically measured by the built-in software of the OCT device. The total retinal thickness (MT) and the thickness of the outer bundle layer (OPL), outer nuclear layer (ONL), external limiting membrane to retinal pigment epithelium (ELM-RPE) in macular OCT images were measured by Image J software. Linear mixed model was used to analyze and compare the thickness of pRNFL, macular fovea and four layers above the nasal and temporal paracentral retina in patients, carriers and normal controls. The correlation between pRNFL and macular retinal sublayer thickness and the course of disease was also analyzed. ResultsThe thickness of the upper and lower pRNFL, temporal pRNFL and average pRNFL of the patients were smaller than those of the carriers and the normal control group (P＜0.01), and the nasal pRNFL thickness of the patients was smaller than that of the carriers (P＜0.01). Fovea: compared with the normal control group, the thickness of MT and ONT in the patient group was decreased, ONL thickness decreased in carrier group, with the significant different (P＜0.05). Parafovea: compared with normal control group, the thickness of MT and temporal ONL decreased and temporal OPL increased in the patients group, with the significant different (P＜0.05). In the carrier group, the thickness of MT and temporal, nasal ONL decreased, and the thickness of nasal OPL increased, with the significant different (P＜0.05). Compared with the carrier group, the MT thickness of the patient group was decreased, and the nasal ONL and nasal ELM-RPE thickness were increased, with the significant different (P＜0.05). Correlation analysis results showed that the thinning of pRNFL in the superior, nasal, temporal and average (r=－0.22, －0.21, －0.25, －0.22), and the thickening of ELM-RPE in foveo-temporal (r=0.19) were correlated with the course of disease (P＜0.05). ConclusionsThe pRNFL of LHON patients with G11778A mutation becomes thinner and is related to the course of the disease. There were significant differences in the thickness of MT and PR sublayers between patients and carriers compared to the normal control group.
