Rapp L M, Fisher P L, Sheinberg C H
Cullen Eye Institute, Baylor College of Medicine, Houston, TX 77030.
Graefes Arch Clin Exp Ophthalmol. 1994 Apr;232(4):232-7. doi: 10.1007/BF00184011.
With aging, the retinal pigment epithelium (RPE) becomes increasingly congested with residual debris called lipofuscin. Little is known about the impact of lipofuscin on retinal function, and this was addressed in the present study by examining the influence of RPE debris on electroretinographic (ERG) parameters utilizing an experimental model of lipofuscin accumulation. Pigmented rats were injected intravitreally with the protease inhibitor leupeptin, and examined 1 week later by electroretinogram (ERG) recording and light and electron microscopy. Relative to vehicle-injected controls, leupeptin-treated retinas showed abundant accumulation throughout the RPE cytoplasm of inclusions that resembled lipofuscin. RPE cells filled with this debris showed a marked increase in height and a displacement of melanin from their apical border. Morphological changes in the RPE had no influence on retinal function since ERG threshold, a- and b-wave maximum amplitude, latency and implicit time were not significantly different between leupeptin-treated eyes and controls. Furthermore, leupeptin-induced RPE inclusions did not alter either the rate or extent of ERG dark adaptation. These findings suggest that filling of the RPE cytoplasm with residual debris is not in itself likely to be the cause of functional alterations in the aging eye.
随着年龄的增长，视网膜色素上皮（RPE）中会逐渐积聚一种名为脂褐素的残余碎片，从而变得愈发充血。关于脂褐素对视网膜功能的影响，人们知之甚少。在本研究中，通过利用脂褐素积累的实验模型，研究RPE碎片对视网膜电图（ERG）参数的影响，从而解决了这一问题。给有色大鼠玻璃体内注射蛋白酶抑制剂亮抑酶肽，1周后通过视网膜电图（ERG）记录以及光学和电子显微镜检查。相对于注射赋形剂的对照组，经亮抑酶肽处理的视网膜在整个RPE细胞质中显示出大量类似于脂褐素的包涵体积累。充满这种碎片的RPE细胞高度明显增加，黑色素从其顶端边界移位。RPE的形态学变化对视网膜功能没有影响，因为在经亮抑酶肽处理的眼睛和对照组之间，ERG阈值、a波和b波最大振幅、潜伏期和隐含时间没有显著差异。此外，亮抑酶肽诱导的RPE包涵体既没有改变ERG暗适应的速率，也没有改变其程度。这些发现表明，RPE细胞质中充满残余碎片本身不太可能是衰老眼睛功能改变的原因。
