Mechanisms of Congenital Hypoventilation

 描述(由申请人提供)：呼吸神经元不完全成熟在围产期会导致严重的发病率，然而呼吸神经元成熟在这一脆弱的时间窗口中发生的机制尚不清楚。因此，迫切需要确定这些围产期呼吸控制的基本神经机制。本研究的目的是阐明呼吸神经元网络成熟的发育过程，并确定围产期呼吸所需的脑干呼吸中枢/回路。中心假设是哺乳动物的后脑呼吸神经元网络在胚胎晚期、围产期和出生后经历了关键的发育成熟，神经元和神经胶质成熟的发育异常参与了自主呼吸神经元功能障碍的病理生理学。拟议的研究灵感来自我们团队对中枢性先天性低通气综合征(CCHS)的研究结果，CCHS是一种罕见的人类疾病，其特征是无法感知二氧化碳，并与PHOX2B多丙氨酸重复序列和非多丙氨酸重复序列(NPARM)突变有关。提出这项研究的理由是，对围产期呼吸需要哪些自主神经回路缺乏基本的基本了解，是实现终极呼吸的障碍。 实施旨在改善早产儿发病率的干预措施。在强大的初步数据指导下，这一假说将通过追求三个具体目标来检验：1)确定显性负NPARM-PHOX2B突变的选择性表达在多大程度上调节围产期化学感觉诱导的呼吸驱动，2)确定NPARM-CCHS中哪些脑干回路丢失，以及3)确定选择性消融脑干星形胶质细胞群促进先天性低通气性的程度。在第一个目标下，我们将使用已经证明的条件转基因小鼠方法，测试定向表达显性负NPARM PHOX2B突变的脑干后对通风控制和脑干解剖的影响。在第二个目标中，我们将结合一种创新的转基因方法来确定哪些脑干回路在先天性低通气性中丢失。在第三个目标中，我们将确定在围产期和出生后适当的自主神经呼吸控制所需的神经元-神经胶质相互作用的程度。这种方法是创新的，因为它使用了来自不同学科的新颖和经过验证的工具、技术和试剂，使我们能够解决以前无法回答的问题。这项拟议的研究意义重大，因为它有望在垂直方向上推进和扩大对哪些神经元-神经胶质回路才能正确控制出生时自主呼吸调节的理解。从这些研究中获得的工具和基本知识将为未来的研究奠定基础，在这些研究中，设计和验证改善早产儿自主呼吸神经功能的干预措施。

 DESCRIPTION (provided by applicant): Incomplete respiratory neuron maturation causes significant morbidity during the perinatal period, yet the mechanisms by which respiratory neuron maturation occurs during this vulnerable time window is not understood. Thus, there is a critical need to identify these basic neural mechanisms of perinatal respiratory control. The objectives of the proposed research are to elucidate developmental processes of respiratory neuron network maturation and to identify brainstem respiratory centers/circuits necessary for perinatal breathing. The central hypothesis is that hindbrain respiratory neuron networks undergo critical developmental maturation during the late embryonic, perinatal, and post-natal periods in mammals, and that developmental abnormalities in neuronal and glial maturation contribute to the pathophysiology of autonomic respiratory neuron dysfunction. The proposed research is inspired by our group's findings of Central Congenital Hypoventilation Syndrome (CCHS), a rare human disorder characterized by an inability to sense CO2 and which is linked to PHOX2B poly-alanine repeat and non-polyalanine repeat (NPARM) mutations. The rationale for the proposed research is that the lack of a basic fundamental understanding of which autonomic neural circuits are required for perinatal breathing represents a barrier to the ultimate implementation of interventions aimed at improving morbidity for premature infants. Guided by strong preliminary data, this hypothesis will be tested by pursuing three specific aims: 1) Determine the extent to which selective expression of a dominant negative NPARM-PHOX2B mutation regulates perinatal chemosensation-induced respiratory drive, 2) Determine which brainstem circuits are lost in NPARM-CCHS, and 3) Determine the extent to which selected ablation of brainstem astrocyte population promote congenital hypoventilation. Under the first aim, we will test the effects on ventilation control and brainstem anatomy after targeted brainstem expression of a dominant negative NPARM PHOX2B mutation using an already proven conditional transgenic mouse approach. In the second aim, we will combine an innovative transgenic approach to identify which brainstem circuits are lost in congenital hypoventilation. In the third aim, we will determine the extent to which neuronal-glial interaction are necessary for appropriate autonomic respiratory control in the perinatal and post-natal period. The approach is innovative because it uses novel and validated tools, techniques, and reagents from distinct disciplines that allow us to address previously unanswerable questions. The proposed research is significant, because it is expected to vertically advance and expand understanding of which neuronal-glial circuits are required for proper control of autonomic regulation of breathing at birth. The tools and basic knowledge gained from these studies will form the foundation of future studies where interventions to improve autonomic respiratory neuron function in premature babies are designed and validated.