Photic history modifies susceptibility to retinal damage in albino trout
Photic history modifies susceptibility to retinal damage in albino trout
复制标题
DOI：
10.1017/s0952523806231031
复制
发表时间：
2006-01-01
影响因子：
1.9
通讯作者：
Allen, DM
中科院分区：
文献类型：
--
作者：
Allison, WT;Hallows, TE;Allen, DM
暴露在强光下的白化脊椎动物通常通过细胞凋亡失去光感受器，因此可以作为视网膜变性的有用模型。相比之下，暴露在强光下的白化虹鳟鱼尽管对杆外段（ROS）造成了实质性的损伤，但仍能维持杆核和锥核的种群数量。本研究的目的是区分两种可能解释这种不同结果的假设：(1)鳟鱼杆核在光损伤期间保持完整，或(2)杆核死亡但被细胞增殖所取代。进一步的目的是研究光史是否会调节视网膜损伤，就像在啮齿动物中一样。将白化鳟鱼和正常着色的鳟鱼从确定的光照环境中移到日光下，而一些没有移到作为保护对照。在有色素的鱼类和受日光保护的白化鱼类中，活性氧一直保持着。暴露在日光下的白化病患者，视网膜中央大部分ROS被去除，而杆状核在核外层维持10天以上。在所有测试的时间点，受影响的白化患者中有大量固缩和tunel标记的杆状核。杆状细胞死亡时，杆状细胞核的数量没有减少，这证实了增殖一定是在取代细胞。事实上，在接受5天破坏性光照射的白化病视网膜祖细胞中观察到短暂的增殖增加。这种增殖反应随着进一步损伤而减弱。即使在杆状核退化的区域，锥体仍保持完整。中弱光预处理影响细胞的死亡和增殖反应，以及视蛋白的异位定位。我们的结论是，在白化鳟鱼视网膜的光损伤过程中，杆状细胞的凋亡而不是视锥细胞的凋亡发生，并且增殖反应具有有限的替换失去的杆状细胞的能力。
Albino vertebrates exposed to intense light typically lose photoreceptors via apoptosis, and thus serve as useful models of retinal degeneration. In contrast, albino rainbow trout exposed to intense light maintain Populations of rod and cone nuclei despite Substantial damage to rod outer segments (ROS). The aim of this Study was to differentiate between two hypotheses that could account for this divergent result: (1) trout rod nuclei remain intact during light damage, or (2) rod nuclei die but are replaced by cell proliferation. A further aim was to examine whether photic history modulates retinal damage, as in rodents. Albino and normally pigmented trout were moved from defined photic regimes into full daylight, while some were not moved to serve as protected controls. ROS were always maintained in pigmented fish and in albinos protected from full daylight. In albinos exposed to full daylight, ROS were removed over most of the central retina, whereas rod nuclei were maintained in the outer nuclear layer over 10 days. Pyknotic and TUNEL-labeled rod nuclei were abundant in affected albinos at all time-points tested. Rod death Occurred without a decrease in the number of rod nuclei, confirming that proliferation must be replacing cells. Indeed a transient increase in proliferation was observed in retinal progenitors of albinos receiving 5 days of damaging light. This proliferative response was decreased with further damage. Cones remained intact even in areas where rod nuclei had degenerated. Pretreatment with light of moderate versus low intensity light affected the cell death and proliferative responses, and the ectopic localization of rod opsin. We conclude that apoptotic demise of rods, but not cones, Occurred during light damage in retinas of albino trout and proliferative responses have a limited a capacity to replace lost rods.