Observation of ultrastructural changes in cultured retinal pigment epithelium following exposure to blue light

1998 ◽  
Vol 236 (9) ◽  
pp. 696-701 ◽  
Author(s):  
Jijing Pang ◽  
Y. Seko ◽  
Takashi Tokoro ◽  
Shizuko Ichinose ◽  
Hiroyuki Yamamoto
2017 ◽  
Vol 104 (4) ◽  
pp. 301-315 ◽  
Author(s):  
H Bardak ◽  
AC Uğuz ◽  
Y Bardak

In this study, we aimed to observe whether curcumin (cur), a polyphenolic compound derived from the dietary spice turmeric, a yellow substance obtained from the root of the plant Curcuma longa Linn, has any protective effect against blue light irradiation in human retinal pigment epithelium (ARPE-19) cells. For this purpose, we evaluated the intracellular calcium release mechanism, poly ADP ribose polymerase (PARP), procaspase-3/-9 protein expression levels, caspase activation, and reactive oxygen species levels. ARPE-19 cells were divided into four main groups, such as control, cur, blue light, and cur + blue light. Results were evaluated by Kruskal–Wallis and Mann–Whitney U tests as post hoc tests. The cells in cur and cur + blue light samples were incubated with 20 μM cur. Blue light exposure was performed for 24 h in an incubator. Lipid peroxidation and cytosolic-free Ca2+ [Ca2+]i concentrations were higher in the blue light exposure samples than in the control samples; however, their levels were determined as significantly lower in the cur and cur + blue light exposure samples than in the blue light samples alone. PARP and procaspase-3 levels were significantly higher in blue light samples. Cur administration significantly decreased PARP and procaspase-3 expression levels. Reduced glutathione and glutathione peroxidase values were lower in the blue light exposure samples, although they were higher in the cur and cur + blue light exposure samples. Caspase-3 and -9 activities were lower in the cur samples than in the blue light samples. Moreover, vascular endothelial growth factor (VEGF) levels were significantly higher in the blue light exposure samples. In conclusion, cur strongly induced regulatory effects on oxidative stress, intracellular Ca2+ levels, VEGF levels, PARP expression levels, and caspase-3 and -9 values in an experimental oxidative stress model in ARPE-19 cells.


1987 ◽  
Vol 230 (1260) ◽  
pp. 339-354 ◽  

We have documented the ultrastructural changes that occur within the photoreceptor outer segment and the retinal pigment epithelium (rpe) during photosensitive membrane turnover. We employed an in vitro eyecup preparation from Xenopus laevis in which a large shedding event was induced by adding the excitatory amino acid l-aspartate (Green-berger & Besharse I985; J . comp . Neurol . 239. 361-372). We found that during L-aspartate-induced shedding the rpe cells formed. on their apical domains, previously undescribed processes that were directly involved in disc phagocytosis. These processes are structurally similar to processes formed by macrophages during phagocytosis and are accordingly referred to as pseudopodia. Pseudopodia were distinguishable from the apical villous process normally extended from the rpe in that they were closely applied to the surface of the outer segment, had a cytoplasmic matrix of low electron density that was devoid of most cellular organelles and were enriched in thin (7 nm diameter) filaments. Filament size, specific pseudopodial staining with the actin-specific probe rhodamine phalloidin and inhibition of pseudopod formation by cytochalasin D suggested that the thin filaments were composed of actin. Pseudopodial formation also occurs during a normal light-initiated shedding event. However, the low frequency of shedding, the asynchrony of the individual shedding events and the transient appearance of the pseudopodia prevented a full appreciation of their role during normal disc shedding. Associated with massive shedding and pseudopodial formation, there was an increased adherence between retina and rpe. During l-aspartate treatment, the apical portions of the rpe cells partitioned with the distal outer segment during retinal isolation. This effect was directly related to the development of pseudopodia and may reflect alteration of surface features of the rod outer segment (ros)-rpe interface related to phagocytosis. Our observations show that transiently forming pseudo­podia are the organelles of phagocytosis and that they may play a role in disc detachment as well.


2017 ◽  
Vol 57 (4) ◽  
pp. 252-262 ◽  
Author(s):  
Bing Lu ◽  
Pengfei Zhang ◽  
Minwen Zhou ◽  
Wenqiu Wang ◽  
Qing Gu ◽  
...  

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