Blue light is a predominant component of light emitting devices (LEDs), which are increasingly present in our environment. There is already accumulating evidence that blue light exposure causes damage to retinal cells in vitro and in vivo; however, much less is known about potential effects of blue light on non-retinal cells. That blue light may be detrimental at the organismal level independent from retinal effect was recently shown by findings that it reduces lifespan in worms and also in flies with genetically ablated retinas. Here, we investigated the effects of blue light exposure across the fly lifespan and found that susceptibility to blue light stress is strongly age-dependent. The blue light of the same intensity and duration reduced survival and increased neurodegeneration more significantly in old flies than in young flies. These differences appear to be caused, at least in part, by impairments of mitochondrial respiratory function. We report that blue light significantly reduces the activity of Complex II in the electron transport system and decrease the biochemical activity of succinate dehydrogenase in both young and old flies. In addition, complex I and complex IV activities are reduced by age, as are ATP levels. We therefore propose that older flies are more sensitive to blue light because the light-induced mitochondrial damage potentiates the age-related impairments in energy metabolism that occurs even in darkness. Taken together, our results show that damaging effects of blue light at the organismal level are strongly age dependent and are associated with reduced activity of specific components of energy producing pathways in mitochondria.

蓝光是发光器件 (LED) 的主要组成部分，它越来越多地出现在我们的环境中。已经有越来越多的证据表明，蓝光暴露会在体外和体内对视网膜细胞造成损害；然而，关于蓝光对非视网膜细胞的潜在影响知之甚少。最近的研究结果表明，蓝光在有机体水平上可能是有害的，与视网膜效应无关，它会降低蠕虫的寿命，也会降低具有基因消融视网膜的果蝇的寿命。在这里，我们调查了蓝光暴露在苍蝇生命周期中的影响，发现对蓝光压力的易感性与年龄密切相关。与年轻果蝇相比，相同强度和持续时间的蓝光在老年果蝇中更显着地降低了存活率并增加了神经退行性变。这些差异似乎至少部分是由线粒体呼吸功能受损引起的。我们报告说，蓝光显着降低了电子传递系统中复合物 II 的活性，并降低了年轻和年老果蝇中琥珀酸脱氢酶的生化活性。此外，复合体 I 和复合体 IV 的活动随着年龄的增长而降低，ATP 水平也是如此。因此，我们提出老年果蝇对蓝光更敏感，因为光诱导的线粒体损伤会增强与年龄相关的能量代谢损伤，即使在黑暗中也会发生这种损伤。总之，我们的研究结果表明，蓝光在有机体水平上的破坏性影响强烈依赖于年龄，并且与线粒体中能量产生途径的特定成分的活性降低有关。