Organisciak D T, Jiang Y L, Wang H M, Bicknell I
Department of Biochemistry, School of Medicine, Wright State University, Dayton, OH 45435.
Invest Ophthalmol Vis Sci. 1990 Jul;31(7):1195-202.
Retinal light damage in dark-reared rats supplemented with ascorbic acid and exposed to multiple doses of intermittent light was studied and compared with damage in unsupplemented dark-reared and cyclic-light-reared rats. The extent of photoreceptor cell loss from intense light exposure was determined by whole-eye rhodopsin levels and retinal DNA measurements two weeks after light treatment. Two weeks after 3 or 8 hr of intermittent light, ascorbate-supplemented animals had rhodopsin and retinal DNA levels that were two to three times higher than in unsupplemented dark-reared rats. In both types of rats rhodopsin levels were influenced by the number of light doses, the duration of light exposure, and to a lesser extent, by the length of the dark period between exposures. Rhodopsin levels in the dark-reared ascorbate-supplemented rats were significantly higher than in unsupplemented dark-reared rats, and were similar to the levels in unsupplemented cyclic-light-reared animals. Ascorbate treatment had no effect on the rate of rhodopsin bleaching. However, regeneration was greater in supplemented rats after multiple 1-hr light exposures. Intermittent light also resulted in lower ascorbate levels in the retinas of supplemented and unsupplemented rats, with dramatic losses from the retinal pigment epithelium (RPE)-choroid in both types of animals. We conclude that ascorbic acid protects the eye by reducing the irreversible Type I form of light damage in dark-reared rats. Ascorbate appears to shift light damage to the Type II form typical of cyclic-light-reared animals.
研究了在黑暗饲养的大鼠中补充抗坏血酸并暴露于多剂量间歇性光照下的视网膜光损伤情况，并与未补充抗坏血酸的黑暗饲养大鼠和周期性光照饲养大鼠的损伤情况进行了比较。在光照处理两周后，通过全眼视紫红质水平和视网膜DNA测量来确定强光暴露导致的光感受器细胞损失程度。在间歇性光照3或8小时两周后，补充抗坏血酸的动物的视紫红质和视网膜DNA水平比未补充抗坏血酸的黑暗饲养大鼠高出两到三倍。在这两种类型的大鼠中，视紫红质水平受光照剂量、光照暴露持续时间的影响，并且在较小程度上受暴露之间黑暗期长度的影响。黑暗饲养且补充抗坏血酸的大鼠的视紫红质水平显著高于未补充抗坏血酸的黑暗饲养大鼠，并且与未补充抗坏血酸的周期性光照饲养动物的水平相似。抗坏血酸处理对视紫红质漂白速率没有影响。然而，在多次1小时光照暴露后，补充抗坏血酸的大鼠中的再生情况更好。间歇性光照还导致补充和未补充抗坏血酸的大鼠视网膜中的抗坏血酸水平降低，两种类型动物的视网膜色素上皮（RPE）-脉络膜中的抗坏血酸都有显著损失。我们得出结论，抗坏血酸通过减少黑暗饲养大鼠中不可逆的I型光损伤来保护眼睛。抗坏血酸似乎将光损伤转变为周期性光照饲养动物典型的II型损伤。
