Plasticity and Regeneration of Retinal Synapses

描述（由申请人提供）：众所周知，光感受器突触末端通过结构变化对损伤和疾病作出反应。在视网膜脱离中，视杆轴突向细胞体缩回，而在人类和动物视网膜变性中，光感受器长出长的神经突或与其他视网膜细胞形成新的突触。这些变化在疾病中是有害的还是有益的尚不清楚，但这些变化确实给视网膜移植带来了希望，因为它们表明感光突触具有结构可塑性。本申请研究了两栖动物和哺乳动物感光细胞中突触变化所涉及的机制，并具有以下具体目标：1）鉴定控制视杆细胞和视锥细胞中轴突可塑性的信号传导途径; 2）确定感光细胞的首选突触靶点以及Muller细胞对突触发生的影响; 3）将结果从两栖动物感光细胞翻译到哺乳动物视网膜。将用环核苷酸信号传导途径的激动剂和拮抗剂处理视杆细胞和视锥细胞，并用免疫细胞化学和共聚焦激光扫描显微镜检查，以检验视杆细胞和视锥细胞分别使用cAMP和cGMP依赖性途径刺激结构变化的假设。通过使用光学镊子进行显微操作，然后使用常规和视频延时显微镜来创建视网膜神经元组，将测试新突触形成过程中潜在的吸引力和排斥力。然后，将在准备用于移植的光感受器片上测试证明最佳生长和突触形成的结果。这些项目探索了损伤后感光突触可塑性的基本机制，并希望为未来通过操纵内源性细胞活动和/或神经元移植来修复视网膜提供合理的基础。

DESCRIPTION (provided by applicant): It is well recognized that the photoreceptor synaptic terminal responds to injury and disease by making structural changes. In retinal detachment the rod axon retracts toward the cell body whereas in human and animal retinal degenerations, the photoreceptors grow long neurites or make new synapses with other retinal cells. Whether these changes are harmful or helpful in disease is unknown but these changes do hold out promise that retinal transplantation is possible since they show that photoreceptor synapses are capable of structural plasticity. This application examines the mechanisms involved in synaptic changes in amphibian and mammalian photoreceptor cells and has the following specific aims: 1) to identify the signaling pathways which control axonal plasticity in rod and cone cells; 2) to determine the preferred synaptic targets for photoreceptors and the influence of Muller cells on synaptogenesis; and 3) to translate the results from amphibian photoreceptors to the mammalian retina. Rod and cone photoreceptors will be treated with agonists and antagonists of cyclic nucleotide signaling pathways and examined with immunocytochemistry and confocal laser scanning microscopy to test the hypothesis that rod and cone cells use cAMP- and cGMP-dependent pathways respectively to stimulate structural change. Creation of groups of retinal neurons by micromanipulation with optical tweezers, followed by conventional and video time lapse microscopy will test potential attractive and repulsive forces during the formation of new synapses. And results which demonstrate optimal growth and synapse formation will then be tested on sheets of photoreceptors prepared for transplantation. These projects explore the fundamental mechanisms involved in the plasticity of the photoreceptor synapse after injury and hope to provide a rational basis for future repair of the retina by manipulation of endogenous cellular activities and/or transplantation of neurons.