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

项目摘要/摘要 脊髓损伤(SCI)在6个胸椎水平(T6)或以上常导致脊柱上的丧失。 对心血管功能的调节。这种功能障碍表现为静息血流动力学异常和 发生直立性低血压和自主神经反射障碍(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率和死亡率的主要原因之一。 虽然目前已有适当的药理和预防措施来缓解这些问题，但它们 缺乏长期疗效，没有解决脊柱上连通性的根本损失。最近，我们 脊髓损伤部分修复后发现移植中缝核源性神经前体细胞(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团之间的连接 脊髓内的细胞群和交感节前神经元。此外，沉默5-羟色胺能 受体5HT2a导致功能恢复丧失。因此，我们假设功能恢复 移植后通过椎管上和椎管内的5-羟色胺能机制进行集中调节。在目标1中，我们 是否会将RN-NPC移植到T4挤压伤大鼠体内并测量包括休息在内的心血管输出量 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重新损伤大鼠 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 脊柱上与移植物的连通性。在目标2中，我们将使用化学遗传学技术来沉默5-羟色胺能 RN-NPC移植后宿主中缝尾侧核神经元是否存在5-羟色胺能调节 对心血管功能的影响已经重建。在目标3中，我们将使用相同的化学发生工具来沉默 移植物衍生的5-羟色胺能神经元，阐明这些神经元是否有助于血流动力学恢复。我们还将 使用5-羟色胺能和去甲肾上腺素能受体拮抗剂来检查哪些脊髓受体参与其中 在重建心血管调节方面。总的来说，这些结果将为潜在的临床应用提供指导。 翻译以减轻脊髓损伤后的血流动力学功能障碍。

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.