Elucidating Serotonergic Mechanisms Regulating Cardiovascular Recovery After Grafting Embryonic Raphe Neurons into the Injured Rat Spinal Cord

阐明将胚胎中缝神经元移植到受伤大鼠脊髓后调节心血管恢复的血清素能机制

• 批准号: 10231367
• 负责人: Cameron T Trueblood
• 金额: $ 3.65万
• 依托单位: DREXEL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2022-03-04
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10231367
• 关键词: Affinity; Animals; Automobile Driving; Autonomic Dysreflexia; Axon; Blood Pressure; Bradycardia; Brain Stem; Cardiovascular Physiology; Cardiovascular system; Cell Nucleus; Cells; Chest; Clinical Treatment; Colorectal; Crush Injury; Development; Devices; Doxazosin; Drug Receptors; Embryo; Etiology; Frequencies; Functional disorder; Health; Heart Rate; Hypotension; Immunohistochemistry; Implant; Incubated; Individual; Injury; Interneurons; Ketanserin; Lesion; Life; Measures; Mediating; Morbidity - disease rate; Neuromodulator; Neurons; Nuclear Pore Complex; Orthostatic Hypotension; Output; Pathway interactions; Patients; Pharmacology; Play; Population; Preventive measure; Quality of life; Rattus; Recovery; Recovery of Function; Regulation; Research; Rest; Role; Serotonin; Severities; Site; Spinal; Spinal Cord; Spinal cord injury; Spinal cord injury patients; Symptoms; Techniques; Telemetry; Therapeutic; Transgenic Organisms; Transplantation; Work; base; clinical translation; designer receptors exclusively activated by designer drugs; effective therapy; efficacy testing; functional loss; functional restoration; hemodynamics; improved; injured; mortality; nerve stem cell; nerve supply; noradrenergic; progenitor; raphe nuclei; receptor; restoration; serotonergic regulation; stem cells; subcutaneous; tool

PROJECT SUMMARY/ABSTRACT Spinal cord injury (SCI) at the 6th thoracic level (T6) or above often results in the loss of supraspinal regulation over cardiovascular function. This dysfunction manifests as abnormal resting hemodynamics and the development of orthostatic hypotension and autonomic dysreflexia (AD). Collectively, these irregularities mark cardiovascular dysfunction as one of the leading causes of morbidity and mortality among the population. Although there are current pharmacological and preventative measures in place to mitigate these issues, they lack long-term efficacy and do not address the underlying loss of supraspinal connectivity. Recently, we discovered grafting raphe nuclei-derived neural progenitors/stem cells (RN-NPCs) after SCI partially restores hemodynamic regulation. More specifically, we found that the graft restores connectivity between raphe nuclei cell populations and sympathetic preganglionic neurons in the spinal cord. Moreover, silencing serotonergic receptor 5HT2A resulted in the loss of functional recovery. Therefore, we hypothesize that functional recovery after grafting is centrally mediated through supraspinal and intraspinal serotonergic mechanisms. In Aim 1, we will graft RN-NPCs into rats sustaining a T4 crush injury and measure cardiovascular output including resting hemodynamics, and AD frequency and severity. Subsequently, we will reinjury the rats above the transplant site and reevaluate all hemodynamic parameters. This will determine if functional restoration is contingent on supraspinal connectivity with the graft. In Aim 2, we will employ chemogenetic techniques to silence serotonergic neurons of the host caudal raphe nuclei after RN-NPC grafting to identify if supraspinal serotonergic regulation of cardiovascular function has been reestablished. In Aim 3, we will use the same chemogenetic tools to silence graft-derived serotonergic neurons, elucidating if these neurons facilitate hemodynamic restoration. We will also administer serotonergic and noradrenergic receptor antagonists to examine which spinal receptors are involved in reestablishing cardiovascular regulation. Collectively, these results will provide guidance for potential clinical translation to mitigate hemodynamic dysfunction after SCI.

项目概要/摘要 第 6 胸椎 (T6) 或以上的脊髓损伤 (SCI) 通常会导致脊髓上神经功能丧失 对心血管功能的调节。这种功能障碍表现为异常的静息血流动力学和 发生直立性低血压和自主神经反射异常（AD）。总的来说，这些违规行为标志着 心血管功能障碍是人群发病和死亡的主要原因之一。 尽管目前有药物和预防措施来缓解这些问题，但它们 缺乏长期疗效，并且不能解决脊髓上连接的潜在丧失。最近，我们 发现 SCI 部分恢复后移植中缝核源性神经祖细胞/干细胞 (RN-NPC) 血流动力学调节。更具体地说，我们发现移植物恢复了中缝核之间的连接 脊髓中的细胞群和交感神经节前神经元。此外，沉默血清素能 受体5HT2A导致功能恢复丧失。因此，我们假设功能恢复 移植后通过脊柱上和脊柱内血清素能机制集中介导。在目标 1 中，我们 将 RN-NPC 移植到遭受 T4 挤压损伤的大鼠体内，并测量心血管输出量，包括静息状态 血流动力学、AD 频率和严重程度。随后，我们将在移植部位上方再次伤害大鼠 并重新评估所有血流动力学参数。这将确定功能恢复是否取决于 与移植物的椎上连接。在目标 2 中，我们将采用化学遗传学技术来沉默血清素能 RN-NPC 移植后宿主尾中缝核的神经元以确定脊髓上血清素能调节是否 心血管功能已恢复。在目标 3 中，我们将使用相同的化学遗传学工具来沉默 移植物衍生的血清素能神经元，阐明这些神经元是否促进血流动力学恢复。我们还将 给予血清素能和去甲肾上腺素能受体拮抗剂以检查涉及哪些脊髓受体 重建心血管调节。总的来说，这些结果将为潜在的临床提供指导 翻译以减轻 SCI 后的血流动力学功能障碍。