Recovery of sacral spinal reflexes after transplantation

描述（由申请人提供）：这是一份修订后的申请文件，申请继续开展一项旨在研究大鼠挫伤后阴茎和肛门外括约肌（“骶骨”）脊髓反射功能恢复的项目，旨在模拟人类脊髓损伤（SCI）。将骶反射的恢复与运动的恢复进行比较。5-羟色胺（5-HT）下行系统被认为参与了这种恢复，在以前的资助期间，提供了SCI后5-HT对骶骨MN的去神经支配和再神经支配的证据。 5-HT出芽的来源被认为是严重挫伤后保留在纤维边缘的少量轴突。 我们已经表明，胶质限制性前体细胞（GRP）可以移植到挫伤，他们改变病变环境，减少胶质瘢痕。修订后的提交材料重点关注的假设是，将GRP移植到SCI后的挫伤病变腔中将导致更多的5-HT发芽，并将增强骶反射和运动的恢复。在目标1中，我们将比较在损伤后9-10天接受挫伤损伤的大鼠中有和没有给予GRP移植的骶骨和运动功能的长期恢复。在目标2中，我们将比较有和没有GRP移植的大鼠中确定的肛门外括约肌（EAS）和球海绵体病（BS）运动神经元（MN）的多巴胺能输入量。在目标3中，我们将通过用顺行示踪剂结合5-HT IHC标记脑干来源的5-HT来检查发芽到骶髓中的来源。这也将使我们能够检验这样一个假设，即备用的下行系统对脊髓的神经再支配保持了原始连接的特异性。这些研究代表了研究SCI和发育生物学的实验室之间的合作，旨在为SCI中胶质前体移植的可能治疗价值提供指导。

DESCRIPTION (provided by applicant): This is a revised submission of a request for continuation of a project aimed at studying functional recovery of penile and external anal sphincter ('sacral') spinal cord reflexes after contusion injuries in rats meant to model human spinal cord injury (SCI). Recovery of sacral reflexes was compared to recovery of locomotion. Serotonergic (5-HT) descending systems are thought to be involved in this recovery, and in the previous funding period, evidence was provided for denervation and reinnervation of sacral MNs by 5-HT after SCI. The source of the 5-HT sprouting is thought to be the small number of axons that remain in the spared rim of fibers after severe contusion SCI. We have shown that glial restricted precursor cells (GRPs) can be transplanted into contusion injuries, and that they alter the lesion environment by reducing glial scarring. The revised submission focuses on the hypothesis that the transplantation of GRPs into the contusion lesion cavity after SCI will result in more 5-HT sprouting and will enhance the recovery of sacral reflexes and locomotion. In aim 1, we will compare the long-term recovery of sacral and locomotor functions in rats receiving contusion lesions with and without GRP transplants given at 9-10 days following injury. In aim 2 we will compare the amount of serotonergic input to identified external anal sphincter (EAS) and bulbospongiosis (BS) motoneurons (MNs) in rats with and without GRP transplants. In aim 3, we will examine the source of the sprouting into the sacral cord by labeling brainstem sources of 5-HT with anterograde tracers combined with 5-HT IHC. This will also allow us to test the hypothesis that the reinnervation of the cord by spared descending systems maintains the specificity of the original connections. These studies represent a collaboration between laboratories studying SCI and developmental biology, and are intended to provide guidance on the possible therapeutic value of glial precursor transplantation in SCI.