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 ）
Cilia are hair-like protuberance on cells of the human body that play a vital role in organs generation and maintenance. Abnormalities of ciliary structure and function affect almost every system of the body, such as the brain, eyes, liver, kidney, bone, reproductive system and so on. Retinal photoreceptor cells are one of sensory neurons which convert light stimuli into neurological responses. This process, called phototransduction, takes place in the outer segments (OS) of rod and cone photoreceptors. OS are specialized sensory cilia, and disruptions in cilia genes, which are causative in a growing number of non-syndromic retinal dystrophies, such as retinitis pigmentosa, Leber’s congenital amaurosis. These syndromes are genetically heterogeneous, involving mutations in a large number of genes. They show considerable clinical and genetic overlap. At present, there are few researches on retinal ciliopathies and clinical treatment strategy. This review shows a comprehensive overview of ciliary dysfunction and visual development related diseases, which contributes to understand the characteristics of these diseases and take early intervention in clinic.
Objective To investigate the effect of astragaloside A (AS-A) on the photoreceptor degeneration induced by sodium iodate (NaIO3) and its related mechanism. MethodsSixty healthy male C57BL/6J mice, aged 6-8 weeks, were randomly divided into normal control (NC) group, NaIO3 group, and AS-A group, with twenty mice in each group. 30 min before modeling, AS-A group mice were intraperitoneally injected with 100 μl AS-A at a dose of 100 mg/kg body weight. 30 min later, mice in NaIO3 group and AS-A group were intraperitoneally injected with 100 μl NaIO3 at a dose of 30 mg/kg body weight. Subsequently, AS-A group mice were administered AS-A twice daily at 12 h intervals until the end of the experiment. On day 1 post-modeling, zonula occludens-1 (ZO-1) immunohistochemistry was performed to observe the structure of retinal pigment epithelium (RPE) cells; real-time quantitative polymerase chain reaction (qPCR) was conducted to detect the mRNA expression of various retinal chemokine ligand-2 (Ccl2), interleukin-1 beta (Il-1β), mixed lineage kinase domain-like protein (Mlkl), receptor-interacting protein kinase 3 (Ripk3), and tumor necrosis factor (Tnf). On day 3 post-modeling, immunohistochemistry was performed to observe the expression of ionized calcium binding adaptor molecule 1 (Iba1) and glial fibrillary acid protein (GFAP) in the retina; TdT-mediated dUTP nick-end labeling (TUNEL) assay was used to detect photoreceptor cell death in each group. On day 4 post-modeling, fundus morphology of mice in each group was observed by fundus color photography and optical coherence tomography (OCT). Hematoxylin-eosin staining (HE) was used to observe the morphological structure of the retina in each group. Inter-group comparisons between two groups were conducted using independent samples t-test, while comparisons among three groups were performed using one-way ANOVA. ResultsFundus color photography and OCT examination showed that a large number of scattered yellow-white subretinal nodular structures in the fundus of NaIO3 group mice, and a large number of strong reflection areas in the RPE layer. The number of strong reflection areas in the RPE layer was reduced in the AS-A group. Immunohistochemical analysis of ZO-1 showed that ZO-1 was largely lost on the RPE cell membrane in that NaIO3 group; whereas in the AS-A group, ZO-1 was evenly distributed on the RPE cell membrane. HE staining results showed circular black deposits were visible in the RPE layer of the NaIO3 group, and the inner and outer segments of photoreceptors were severely damaged, with a significant decrease in the number of outer nuclear layer (ONL) cell nuclei; whereas in the AS-A group, the RPE layer pigments were orderly, the inner and outer segments of photoreceptors were intact, and the number of ONL cell nuclei significantly increased. The results of TUNEL staining show that numerous TUNEL-positive cell nuclei were observed in the ONL of the retina in the NaIO3 group, while the number of TUNEL-positive cell nuclei in the ONL of the retina was significantly reduced in the AS-A group, with statistically significant differences (t=2.66, P＜0.05). The analysis of qPCR data showed that compared with the AS-A group, the relative expression levels of Mlkl, Ripk3, Ccl2, Il-1β and Tnf mRNA in the retina were significantly increased in the NaIO3 group, with statistically significant differences (F=39.18, 10.66, 53.51, 41.40, 24.13; P＜0.001). Immunohistochemical staining results showed that compared with NC group and AS-A group, the positive expression of GFAP in retina of NaIO3 group was significantly increased, and the difference was statistically significant (F=9.62, P＜0.05). ConclusionAS-A antagonizes NaIO3-induced photoreceptor degeneration in part by inhibiting photoreceptor cell death and neuroinflammation. Meanwhile, AS-A treatment protects against NaIO3-triggered perturbation of retinal homeostasis.
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)
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.
Objective To investigate the correlation of ascorbic acid distribution and retinal susceptibility to iron toxicity of the retina.Methods Autoclaved iron particles of 5 mg and 15 mg were implanted into the vitreous cavities of 32 Spragu-Dawley (SD) rats and 9 rabbits, respectively. The retinal sections of rats and rabbits were examined after hemotoxylin-eosin (HE) staining. Apoptos is of rabbits′retinal neurons was investigated by TdT-mediated dUTP-biotin nick-end labeling (TUNEL). Chinoy′s method was used to observe the distribution of as corbic acid in the retinae of the 2 kinds of animals.Results In rats, histological and structural densification was observed only in the photoreceptor cells after implantation of the iron particles. In rabbits, however, histological and structural destruction as well as TUNEL-positive nuclei were observed in all neuronal layers of the retina 3 days after the implantation of the iron particles. Silver granules reduced by ascorbic acid from silver nitrate were observed only in the outer nuclear layer in normal rats retinae, while they were observed evenly throu ghout all layers of rabbits′retinae. Conclusions The suscept ibility of retina to iron toxicity is correlated to the distribution of ascorbic acid in retina. (Chin J Ocul Fundus Dis，2003，19：269-332)
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 investigate the mechanism of the toxic effect of N methyl N-nitrosourea (MNU) on photoreceptor cell apoptosis of rat’s retina. Methods Thirty 50-day-old female Sprague-Dawley ( SD ) rats were intraperitoneally injected with MNU (60 mg/kg) and were put to death by dislocation of cervical vertebra 12, 24, 48, and 72 hours and 7 days after the injection, respectively. The photoreceptor cell apoptosis was detected by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) and transmission electron microscope. The expression of proliferating cell nuclear antigen (PCNA), vimentin and glial fibrillary acidic protein (GFAP) was detected at different time after injection by immunohistochemical methods. Results The apoptotic index of the retina in the posterior pole was (33. 6±2. 3), (46. 5±5. 7), (20. 1±5. 3), (8. 2±3. 6) and (2. 5±1. 3~//oo at the 12th,24th, 48 th, and 72nd hour and on the 7th day, respectively, after injection. Karyopyknosis was found in most photoreeeptor cells 24 hours after injection. The expression of PCNA was found in internal granularlayer and between internal granular layer and choroid 24 hours after injection, reached the peak after 72 hours, and reduced obviously after 7 days. The positive expression of GFAP and vimentin was found in internal and external granular layer 24 hours after injection, reached the peak after 72 hours, and reducedobviously after 7 days.Conclusion MNU may selectively lead the photoreceptor cell apoptosis and proliferation of Mvller cells. (Chin J Ocul Fundus Dis，2004，20：33-36)
Aminoadipic acid(AAA) is known to damage retinal glia cells primarily when it is given to animals intravitreally. The present study is to demonstrate marked increase of retinal susceptibility to photic damage following administration of sub-thres-hold doses of this agent to albino rats. Right eyes were intravitreally injected with 10 ?l of 10 mM AAA, a dose which caused transient swelling of Muller cell nucleiimmediately after treatment, and total recovery by 24 hours. These rats were exposed to fluorescent light at 150 f.c. for one hour three days after injection. The left eyes were injected with the same amount of physiologic saline solution and exposed to light with an identical time schedule. The animals were killed at the 24th hour,third and seventh day, following light exposure. Cytologic changes in the retinae of both eyes were compared light microscopically. The light exposed left eyes showed mild disorganization of photoreceptor outer segements. Usually this change disappeared by the seventh day. AAA-injected right eyes showed marked destruction in the photoreceptor cell layer. The change in the photoreceptor cells was progressive and disappearance of outer segments and degeneration of numerous nuclei occurred during the following period. （Chin J Ocul Fundus Dis,1992,8:17-19）
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.