Thomson Lauren R, Toyoda Yoko, Langner Andrea, Delori Francois C, Garnett Kevin M, Craft Neal, Nichols Cathleen R, Cheng Kimberly M, Dorey C Kathleen
Schepens Eye Research Institute, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA.
Invest Ophthalmol Vis Sci. 2002 Nov;43(11):3538-49.
Inferential evidence indicates that macular pigments (lutein and zeaxanthin) protect photoreceptors and/or retard age-related macular degeneration. These experiments tested the hypothesis that retinal zeaxanthin prevents light-induced photoreceptor cell death.
Retinal damage was assessed in quail fed a carotenoid-deficient (C-) diet for 6 months. Groups of 16 birds (8 male, 8 female) were fed a C- diet supplemented with 35 mg 3R,3'R-zeaxanthin for 1, 3, or 7 days; one group was continued on C- diets. Half of each group was exposed to intermittent 3200-lux white light (10 1-hour intervals separated by 2 hours in dark). After 14 additional hours in the dark, one retina of each quail was collected for HPLC analysis, and the contralateral retina was embedded in paraffin for counts of apoptotic nuclei.
After 7 days' supplementation, concentrations of zeaxanthin in serum, liver, and fat had increased by factors of 50.8, 43.2, and 6.5, respectively (all P < 0.001). In contrast, retinal zeaxanthin fluctuated significantly upward on day 3, but there was no net change on day 7. The number of apoptotic rods and cones in light-damaged eyes correlated significantly and inversely with zeaxanthin concentration in the contralateral retina (r = -0.61; P < 0.0001 and r = -0.54; P < 0.002), but not with serum zeaxanthin. Similar correlations were observed with retinal lutein, which correlated strongly with retinal zeaxanthin (r = 0.95; P < 0.0001).
Retinal zeaxanthin dose dependently reduced light-induced photoreceptor apoptosis; elevated serum levels did not. These data provide the first experimental evidence that xanthophyll carotenoids protect photoreceptors in vivo.
推断性证据表明黄斑色素（叶黄素和玉米黄质）可保护光感受器和/或延缓年龄相关性黄斑变性。这些实验检验了视网膜玉米黄质可预防光诱导的光感受器细胞死亡这一假说。
对喂食缺乏类胡萝卜素（C-）饮食6个月的鹌鹑的视网膜损伤情况进行评估。将16只鸟（8只雄性，8只雌性）分为几组，分别喂食添加了35毫克3R,3'R-玉米黄质的C-饮食1天、3天或7天；一组继续喂食C-饮食。每组中的一半暴露于间歇性3200勒克斯白光下（10个1小时的光照间隔，间隔2小时处于黑暗中）。在黑暗中额外放置14小时后，收集每只鹌鹑的一个视网膜用于高效液相色谱分析，对侧视网膜则嵌入石蜡中用于凋亡细胞核计数。
补充7天后，血清、肝脏和脂肪中的玉米黄质浓度分别增加了50.8倍、43.2倍和6.5倍（均P < 0.001）。相比之下，视网膜玉米黄质在第3天显著上升，但在第7天没有净变化。光损伤眼中凋亡的视杆细胞和视锥细胞数量与对侧视网膜中的玉米黄质浓度显著负相关（r = -0.61；P < 0.0001和r = -0.54；P < 0.002），但与血清玉米黄质无关。视网膜叶黄素也观察到类似的相关性，其与视网膜玉米黄质高度相关（r = 0.95；P < 0.0001）。
视网膜玉米黄质剂量依赖性地减少光诱导的光感受器凋亡；血清水平升高则无此作用。这些数据提供了首个叶黄素类胡萝卜素在体内保护光感受器的实验证据。
