RETINAL GANGLION CELL AXON-TARGET INTERACTIONS

我的研究的长期目标是了解指导 视束上的视网膜神经节细胞轴突及其导向 到适当的目标地区。这笔赠款的具体目的是 了解(I)靶点(即上丘)如何影响 神经节细胞和正在生长的视神经轴突以及(Ii)如何扩散因子 来源于神经支配的靶区可能受到调控。整体而言 这些实验要检验的假设是扩散因素 上丘在视网膜轴突支配时释放 影响视网膜神经节存活和突起生长的因素 细胞。这些问题将通过体外研究来解决， 使用神经移植的进一步研究，以及在检查 营养因子基因在大鼠上丘的表达 发展。第一组研究将检验 靶区移植对视神经轴突的影响 生长：视网膜外植体在胶原凝胶培养中，或在基质中 包被细胞黏附分子L1的细胞将与 上丘测试先前神经支配的靶点 影响视神经轴突的生长。一项平行的研究将检验 活体中的视轴突被异位靶点吸引。第二组 的研究将检查靶向衍生因子对视网膜的影响 神经节细胞：第一个将使用视网膜神经节细胞生物测定来 无神经上位培养上清条件下的体外实验 丘脑(来源于神经支配前的正常小鼠或来自先天 盲鼠)缺乏一种蛋白质，这种蛋白质存在于 神经支配SC。第二项研究将使用原位杂交技术 上丘脑源性神经营养因子基因表达与视轴突间的关系 输入。 虽然这些研究的主要目标是解决一个基本的 发育问题(对视网膜神经节细胞如何 轴突与它们的靶相互作用)，这些研究也直接 对形成光学连接的治疗努力的研究的影响 在受损或缺陷的视觉系统中。

The long-term goal of my research is to understand the factors that guide retinal ganglion cell axons along the optic tract and which direct them to appropriate target regions. The specific aim of this grant is to understand (i) how the target (i.e., the superior colliculus) affects ganglion cells and growing optic axons and (ii) how diffusible factors derived from innervated target regions might be regulated. The overall hypothesis to be tested by these experiments is that diffusible factors released by the superior colliculus upon innervation by retinal axons influence the survival of and neurite outgrowth from retinal ganglion cells. These issues will be addressed with in vitro studies, with further studies using neural transplants and in studies which examine the expression of trophic factor genes in the superior colliculus during development. The first group of studies will examine the ability of explanted and transplanted target regions to influence optic axon outgrowth: retinal explants in collagen gel cultures, or on substrates coated with the cell-adhesion molecule L1, will be co-cultured with superior colliculus to test whether previously innervated targets influence optic axon outgrowth. A parallel study will examine whether optic axons in vivo are attracted to an ectopic target. A second group of studies will examine the effects target-derived factors on retinal ganglion cells: the first will use a retinal ganglion cell bioassay to test in vitro whether media conditioned by non-innervated superior colliculus (derived from pre-innervation normal mice or congenitally blind mice) lacks a protein that is present in the active fraction of innervated SC. The second study will use in situ hybridization techniques to correlate BDNF mRNA levels in the superior colliculus with optic axon input. Although the main goal of these studies is to address a basic developmental question (an understanding of how retinal ganglion cell axons interact with their target), these studies also have direct implications for studies on therapeutic efforts to form optic connections in damaged or deficient visual systems.