Age-related changes in the photoreactivity of retinal lipofuscin granules:: Role of chloroform-insoluble components
Age-related changes in the photoreactivity of retinal lipofuscin granules:: Role of chloroform-insoluble components
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DOI：
10.1167/iovs.03-0277
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发表时间：
2004-04-01
影响因子：
4.4
通讯作者：
Simon, JD
中科院分区：
文献类型：
--
作者：
Rózanowska, M;Pawlak, A;Simon, JD
目的。随着年龄的增长，脂褐素在人视网膜色素上皮(RPE)细胞中积累，这可能是RPE对光氧化敏感性随年龄增加的主要原因。随着脂褐素的组成、吸收和荧光发生与年龄相关的变化，本研究的目的是确定脂褐素颗粒的光反应性是否也随供体年龄的变化而变化。方法：从人RPE中分离脂褐素颗粒，并将其分组，以确定脂褐素本身的光反应性是否与年龄有关。通过测量光诱导氧摄取和活性氧物种的光生成的作用光谱来评价光反应性。用Folch‘s萃取法分离氯仿可溶组分(CHS)和不溶组分(CHNS)，以确定导致脂褐素光反应性随年龄增加的因素。结果观察到光诱导氧摄取和超氧化物衍生自旋加合物积累的速率表明，当归一化到相同数量的脂褐素颗粒时，脂褐素的有氧光反应性随着年龄的增加而增加。CHS和CHNS都介导了单线态氧、超氧阴离子的光生，以及添加的脂质和蛋白质的光氧化。尽管CHS和CHNS都表现出显著的光反应性，但当归一化到相同的干质量时，两者都没有表现出与年龄相关的显著变化。相反，脂褐素颗粒中CHNS的含量随着年龄的增长而显著增加。结论RPE脂褐素的有氧光反应活性随年龄的增长而显著增强。这种影响可能归因于不溶组分含量的增加。
PURPOSE. Lipofuscin accumulates in human retinal pigment epithelium (RPE) cells with age and may be the main factor responsible for the increasing susceptibility of RPE to photooxidation with age. As the composition, absorption, and fluorescence of lipofuscin undergo age-related changes, the purpose of this study was to determine whether photoreactivity of lipofuscin granules also changes with the donor age.METHODS. To determine whether the photoreactivity of lipofuscin itself is age related, lipofuscin granules were isolated from human RPE and pooled into age groups. Photoreactivity was assessed by measuring action spectra of photo-induced oxygen uptake and photogeneration of reactive oxygen species. Separation of chloroform-soluble (ChS) and - insoluble (ChNS) components by Folch's extraction was used to determine the factors responsible for the age-related increase in lipofuscin photoreactivity.RESULTS. The observed rates of photo-induced oxygen uptake and photo-induced accumulation of superoxide-derived spin adducts indicated that when normalized to equal numbers of lipofuscin granules, aerobic photoreactivity of lipofuscin increased with age. Both ChS and ChNS mediated photogeneration of singlet oxygen, superoxide radical anion, and photooxidation of added lipids and proteins. Although both ChS and ChNS exhibited substantial photoreactivities, neither exhibited significant age-related changes when normalized to equal dry mass. In contrast, ChNS contents in lipofuscin granules significantly increased with aging.CONCLUSIONS. Aerobic photoreactivity of RPE lipofuscin substantially increases with aging. This effect may be ascribed to the increased content of insoluble components.