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Lilla Knels, Monika Valtink, Cora Roehlecke, Mirko Mehner, Richard H. Funk; Cell Decline Upon Blue Light Exposure On Retinal Neuronal Cell Cultures. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5348.
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© ARVO (1962-2015); The Authors (2016-present)
It was shown that visible short wave (blue) light can trigger retinal degeneration by damaging photoreceptor cells, but the effect of blue light on retinal ganglion cells is largely unknown. We therefore investigated the effect of blue light in retinall neuronal cells in vitro.
R28 retinal neuronal cells were incubated under three different light irradiations (405nm / 0.6W/m2, 405nm / 1.5W/m2, 405nm / 4.5W/m2, or 470nm / 4.5W/m2) for 6h or 24h. Light-induced apoptotic changes were determined by flow cytometric analysis of caspases 3, 8 and 9, by activity assaying for caspases 3, 8 and 9 (Promega), and by western blotting for caspase 3 and cleaved PARP (p85 fragment). In addition, after 15min, 90min, 6h, 24h or 48h of light treatment, total intracellular reactive oxygen species (ROS) and mitochondrial ROS (mitoSOX, Invitrogen) were determined by flow cytometry.
Exposure to blue light with a wavelength of 405nm and an intensity of 4.5W/m2 led to increased numbers of caspase-3 and -9 positive cells after 6h, and increased numbers of caspase-3, -8 and -9 positive cells after 24h, compared to controls and to the other treatment groups. The activity of caspases 3, 8 and 9 was significantliy increased after a 6h exposure to blue light (405nm, 4.5W/m2), and was significantly reduced after 24h. Western blotting revealed that 405nm (4.5W/m2) irradiation increased protein levels of procaspase-3 (35kD), cleaved caspase-3 (17kD) and cleaved PARP after 24h. Mitochondrial ROS remained unchanged during the first 6h of light exposure, but were significantly elevated after 24h and 48h exposure to 405nm (4.5W/m2) light. Total intracellular ROS was already increased after 15min and 90min irradiation, but was significantly lower after 24h irradiation with light of 405nm (4.5W/m2). The other tested wavelength / intensity combinations did not harm retinal ganglion cells during the observation period.
R28 cells undergo caspase-3 dependent apoptosis after irradiation with 405nm (4.5W/m2) blue light. The rate of oxidative stress and cell death caused by blue light is directly proportional to the light intensity and inversely proportional to its wavelength.
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