Plasticity and Regeneration of Retinal Synapses

描述(申请人提供)：众所周知，光感受器突触终末通过结构变化对损伤和疾病做出反应。在视网膜脱离中，杆状轴突向细胞体收缩，而在人和动物的视网膜变性中，光感受器长出长的轴突或与其他视网膜细胞形成新的突触。这些变化对疾病是有害的还是有帮助的尚不清楚，但这些变化确实表明视网膜移植是可能的，因为它们表明光感受器突触具有结构可塑性。这项应用研究了两栖动物和哺乳动物光感受器细胞中涉及突触变化的机制，并有以下具体目的：1)确定控制视杆细胞和视锥细胞轴突可塑性的信号通路；2)确定光感受器的首选突触靶点和Muller细胞对突触发生的影响；以及3)将两栖动物光感受器的结果转化为哺乳动物的视网膜。用环核苷酸信号通路的激动剂和拮抗剂处理视杆细胞和视锥细胞，用免疫细胞化学和激光共聚焦扫描显微镜检验视杆细胞和视锥细胞分别使用cAMP和cGMP依赖途径刺激结构改变的假说。用光学镊子通过显微操作创建视网膜神经元组，然后使用传统的和视频时间推移显微镜，将测试在形成新突触期间潜在的吸引力和排斥力。然后，显示最佳生长和突触形成的结果将在为移植准备的光感受器上进行测试。这些项目探索了光感受器突触在损伤后可塑性的基本机制，并希望通过操纵内源性细胞活动和/或神经元移植为未来视网膜的修复提供合理的基础。

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.