Lutein and zeaxanthin concentrations in rod outer segment membranes from perifoveal and peripheral human retina.
Lutein and zeaxanthin concentrations in rod outer segment membranes from perifoveal and peripheral human retina.
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发表时间：
2000-04
影响因子：
4.4
通讯作者：
L. Rapp;Seema S. Maple;J. Choi
中科院分区：
文献类型：
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作者：
L. Rapp;Seema S. Maple;J. Choi
目的除了充当光学过滤器之外，黄斑（类胡萝卜素）色素还被假设通过抑制长链多不饱和脂肪酸的过氧化而在人类视网膜中发挥抗氧化剂的作用。然而，在中心凹视网膜内层（感受器前）密度最高的位置，无法预测抗氧化保护的具体要求。本研究的目的是确定叶黄素和玉米黄质（构成黄斑色素的主要类胡萝卜素）是否存在于视杆外节（ROS）膜中，其中长链多不饱和脂肪酸的浓度和氧化敏感性最高。方法 解剖来自人类供体眼睛的视网膜以获得两个区域：一个偏心率为 1.5 至 4 毫米的环形圈，代表不包括中央凹的中央区域（中心凹周围视网膜）和该区域之外的剩余视网膜（周边视网膜）。通过差速离心从这些区域分离出 ROS 和残余（ROS 耗尽）视网膜膜，并通过聚丙烯酰胺凝胶电泳和脂肪酸分析检查其纯度。通过高效液相色谱分析叶黄素和玉米黄质，并以相对于膜蛋白的浓度表示它们的浓度。在牛视网膜上同时进行膜的制备和类胡萝卜素的分析，以与非灵长类动物进行比较。还测定了从人眼采集的视网膜色素上皮的类胡萝卜素浓度。结果发现，从人视网膜的中心凹和周边区域制备的 ROS 膜具有高纯度，如蛋白质凝胶上存在致密的视蛋白条带所示。人 ROS 膜的脂肪酸分析显示，相对于残留膜，二十二碳六烯酸具有特征性富集。从牛视网膜制备的膜具有与人类视网膜相似的蛋白质谱和脂肪酸组成。类胡萝卜素分析表明，叶黄素和玉米黄质存在于 ROS 和残留的人视网膜膜中。人 ROS 中叶黄素和玉米黄质的组合浓度比残膜中高 70%。人 ROS 膜中的叶黄素和玉米黄质在中心凹周围的浓度是周边视网膜区域的 2.7 倍。在人视网膜色素上皮中始终检测到浓度相对较低的叶黄素和玉米黄质。结论 人 ROS 膜中叶黄素和玉米黄质的存在增加了它们在该细胞区室中充当抗氧化剂的可能性。在中心凹周围视网膜的 ROS 中发现这些类胡萝卜素浓度较高，这支持了它们在年龄相关性黄斑变性中的保护作用。
PURPOSE In addition to acting as an optical filter, macular (carotenoid) pigment has been hypothesized to function as an antioxidant in the human retina by inhibiting the peroxidation of long-chain polyunsaturated fatty acids. However, at its location of highest density in the inner (prereceptoral) layers of the foveal retina, a specific requirement for antioxidant protection would not be predicted. The purpose of this study was to determine whether lutein and zeaxanthin, the major carotenoids comprising the macular pigment, are present in rod outer segment (ROS) membranes where the concentration of long-chain polyunsaturated fatty acids, and susceptibility to oxidation, is highest. METHODS Retinas from human donor eyes were dissected to obtain two regions: an annular ring of 1.5- to 4-mm eccentricity representing the area centralis excluding the fovea (perifoveal retina) and the remaining retina outside this region (peripheral retina). ROS and residual (ROS-depleted) retinal membranes were isolated from these regions by differential centrifugation and their purity checked by polyacrylamide gel electrophoresis and fatty acid analysis. Lutein and zeaxanthin were analyzed by high-performance liquid chromatography and their concentrations expressed relative to membrane protein. Preparation of membranes and analysis of carotenoids were performed in parallel on bovine retinas for comparison to a nonprimate species. Carotenoid concentrations were also determined for retinal pigment epithelium harvested from human eyes. RESULTS ROS membranes prepared from perifoveal and peripheral regions of human retina were found to be of high purity as indicated by the presence of a dense opsin band on protein gels. Fatty acid analysis of human ROS membranes showed a characteristic enrichment of docosahexaenoic acid relative to residual membranes. Membranes prepared from bovine retinas had protein profiles and fatty acid composition similar to those from human retinas. Carotenoid analysis showed that lutein and zeaxanthin were present in ROS and residual human retinal membranes. The combined concentration of lutein plus zeaxanthin was 70% higher in human ROS than in residual membranes. Lutein plus zeaxanthin in human ROS membranes was 2.7 times more concentrated in the perifoveal than the peripheral retinal region. Lutein and zeaxanthin were consistently detected in human retinal pigment epithelium at relatively low concentrations. CONCLUSIONS The presence of lutein and zeaxanthin in human ROS membranes raises the possibility that they function as antioxidants in this cell compartment. The finding of a higher concentration of these carotenoids in ROS of the perifoveal retina lends support to their proposed protective role in age-related macular degeneration.