REGULATION OF DORSAL ROOT AXON BRANCHING BY NEUROTROPHIN

神经营养因子对背根轴突分支的调节

• 批准号: 2269721
• 负责人: WILLIAM D SNIDER
• 金额: $ 18.44万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-04-07 至 1997-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2269721
• 关键词: afferent nerve; axon; capsaicin; cell death; cell growth regulation; cell type; developmental neurobiology; embryo /fetus; fluorescent dye /probe; gene expression; growth factor receptors; in situ hybridization; laboratory rat; microscopy; neurogenesis; neuronal transport; neurotrophic factors; protein tyrosine kinase; receptor expression; spinal cord; spinal ganglion

The purpose of this work is to assess the influence of neuronal growth factors on axon branching in the mammalian spinal cord. The dorsal root afferent projection has been chosen as a model system because four members of the "neurotrophin" family of growth factors are known to promote neurite outgrowth of dorsal root ganglion (DRG) cells in vitro. Furthermore, each of the physiologically specified classes of DRG cells has a characteristic axonal arborization in the spinal cord that can be fully and conveniently stained with lipid-soluble tracers. A first step is to determine which classes of DRG cells express which members of the trk family of high-affinity neurotrophin receptors. Rat DRG cells expressing different trk's will be identified by retrograde tracing from characteristic peripheral and central target fields, followed by in situ hybridization with probes for trkA, trkB, and trkC. Second, we will determine the developmental time course of synthesis of the different neurotrophins in the central target fields of DRG cells. In situ hybridization in developing rat spinal cord will be performed with probes for NGF, BDNF, NT3, and NT5. Expression of neurotrophins by spinal cord neurons will be correlated with the development of axonal arborizations of the different classes of DRG cells as revealed by staining with lipid-soluble tracers. Finally, we will determine whether neurotrophins can influence dorsal root axon branching in the spinal cord. NGF, BDNF, NT3, and NT5 will in injected into embryos in utero and the dorsal root afferent projections in control and experimental animals will be stained with Dil. The important characteristics of axonal arbors will be quantitated and compared in control and growth factor-treated animals. These experiments will determine which high-affinity neurotrophin receptors are expressed by identified classes of DRG cells, the relationship of neurotrophin expression in spinal target fields to the development of arborizations of different classes of DRG neurons, and whether neurotrophins can influence the spinal arbors of DRG cells in vivo. Determining the effects of neurotrophins on the growth and branching of dorsal root axons in vivo is crucial to an assessment of their potential as agents to promote regeneration of sensory axons in the spinal cord.

这项工作的目的是评估神经元生长的影响 影响哺乳动物脊髓轴突分支的因素。 背部 选择根传入投影作为模型系统是因为四个 已知生长因子“神经营养素”家族的成员 在体外促进背根神经节 (DRG) 细胞的神经突生长。 此外，每个生理学上指定的 DRG 细胞类别 在脊髓中具有特征性的轴突树枝化，可以 可以用脂溶性示踪剂充分、方便地染色。 第一步是确定哪些类别的 DRG 细胞表达哪些 高亲和力神经营养素受体 trk 家族的成员。 鼠 表达不同trk的DRG细胞将通过逆行鉴定 从特征性外围和中心目标区域追踪， 然后用 trkA、trkB 和 trkC 探针进行原位杂交。 其次，我们将确定合成的发展时间进程 DRG 中央靶区不同神经营养因子的分布 细胞。 原位杂交在大鼠脊髓发育中的应用 使用 NGF、BDNF、NT3 和 NT5 探针进行。 表达 脊髓神经元的神经营养因子将与 不同类型 DRG 的轴突树枝化的发育 通过脂溶性示踪剂染色显示的细胞。 最后，我们 将确定神经营养素是否可以影响背根轴突 脊髓中的分支。 NGF、BDNF、NT3 和 NT5 将注射 进入子宫内的胚胎和背根传入投射 对照和实验动物将用 Dil 染色。 这 轴突乔木的重要特征将被量化并 与对照动物和生长因子处理的动物进行比较。 这些实验将确定哪种高亲和力神经营养蛋白 受体由已识别的 DRG 细胞类别表达， 脊髓靶区神经营养蛋白表达与神经营养因子的关系 不同类别的 DRG 神经元的树枝状发育，以及 神经营养因子是否可以影响DRG细胞的脊髓乔木 体内。 确定神经营养素对生长和发育的影响 体内背根轴突的分支对于评估 它们作为促进感觉轴突再生的潜力 脊髓。