Eph/ephrin expression in the adult rat visual system following localized retinal lesions: localized and transneuronal up-regulation in the retina and superior colliculus
Eph/ephrin expression in the adult rat visual system following localized retinal lesions: localized and transneuronal up-regulation in the retina and superior colliculus
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DOI：
10.1111/j.1460-9568.2005.04381.x
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发表时间：
2005-10-01
影响因子：
3.4
通讯作者：
Dunlop, SA
中科院分区：
文献类型：
--
作者：
Rodger, J;Symonds, ACE;Dunlop, SA
在成年PVG戴帽大鼠单侧视神经切断后，轴突导向因子ephrin-A2在尾侧上丘（SC）中上调，而在头侧上级丘（SC）中不上调，并且EphA 5受体在切断轴突的视网膜神经节细胞（RGC）中下调。尽管视网膜-丘投射大部分是交叉的，但变化发生在双侧。在这里，我们调查的动态Eph/ephrin表达采用原位杂交和半定量免疫组织化学局部视网膜病变后。单侧氪激光损伤背鼻侧视网膜消融对侧投射的RGCs（DN组）;腹颞侧损伤消融对侧和同侧投射的RGCs（VT组）。整个视网膜的病变作为对照（总组）。将结果与正常动物进行比较，其中顶盖ephrin-A2和视网膜EphA 5分别表达为浅上升的喙尾和鼻颞梯度。在DN组和Total组的SC中，顶盖ephrin-A2在尾部上调;在VT组中，表达在双侧保持正常。单侧丘消融表明，通过丘间通路介导的ephrin-A2表达的双边变化。VT组中EphA 5的表达在实验视网膜的完整鼻区域中升高。对于每个实验组，EphA 5表达在对侧眼的鼻视网膜中也升高，导致跨鼻颞轴的均匀表达。上调ephrin-A2在尾部，但不是喙，SC表明，作为一个结果，损伤的发展位置信息的增强。视网膜EphA 5表达的双侧增加表明上调信号在眼间起作用。这项研究表明，信号调节指导线索的表达都是本地化和中继transneuronalised。
Following unilateral optic nerve section in adult PVG hooded rat, the axon guidance cue ephrin-A2 is up-regulated in caudal but not rostral superior colliculus (SC) and the EphA5 receptor is down-regulated in axotomised retinal ganglion cells (RGCs). Changes occur bilaterally despite the retino-collicular projection being mostly crossed. Here we investigate the dynamics of Eph/ephrin expression using in situ hybridization and semi-quantitative immunohistochemistry after localized retinal lesions. Unilateral krypton laser lesions to dorso-nasal retina ablated contralaterally projecting RGCs (DN group); ventro-temporal lesions ablated contralaterally and ipsilaterally projecting RGCs (VT group). Lesions of the entire retina served as controls (Total group). Results are compared to normal animals in which tectal ephrin-A2 and retinal EphA5 are expressed, respectively, as shallow ascending rostro-caudal and naso-temporal gradients. In both SCs of DN and Total groups, tectal ephrin-A2 was up-regulated caudally; in the VT group, expression remained normal bilaterally. Unilateral collicular ablation indicated that bilateral changes in ephrin-A2 expression are mediated via intercollicular pathways. EphA5 expression in the VT group was elevated in the intact nasal region of experimental retinae. For each experimental group, EphA5 expression was also elevated in nasal retina of the opposite eye, resulting in uniform expression across the naso-temporal axis. Up-regulation of ephrin-A2 in caudal, but not rostral, SC suggests the enhancement of developmental positional information as a result of injury. Bilateral increases in retinal EphA5 expression demonstrate that signals for up-regulation operate interocularly. The study demonstrates that signals regulating guidance cue expression are both localized and relayed transneuronally.