从表观遗传学层面探讨NMDA受体激活在宫内缺氧所致生后肺泡发育不良中的作用及机制

Intrauterine hypoxia is a common cause of fetal growth restriction. Lung alveolar development in mammals at birth is far from complete. Various factors against fetal intrauterine growth will not only seriously affect the normal development of fetal lung, but also influence the postnatal alveolar development, therefore result in adult abnormal alveolar structure and lung function, which is the cause of adult lung diseases. Based on the preliminary research, the applicant proposes to investigate the effect of the activation of NMDA receptors ' in the fetal rats' postnatal alveolar dysplasia induced by intrauterine hypoxia in vivo and at fetal lung organic culture level. In addition, the applicant proposes to determine the role of the activation of NMDA receptors in the down-regulation of peroxisome proliferator-activated receptor-r (PPAR-r) gene(a key gene of regulating the lung development after birth) expression, and further examine the epigenetic mechanism and significance of down-regulation of PPAR-r gene expression in the level of DNA Methylation, in order to reveal the role and molecular mechanisms of activation of lung NMDA receptors in the fetal rats postnatal alveolar dysplasia induced by intrauterine hypoxia. This project aims to clarify the hypothesis at in vovo, organ and molecular level that glutamate is one of the important damage factor in postnatal alveolar dysplasia induced by intrauterine hypoxia by the activation of NMDA receptors, and the completion of this project will provide a new target for the prevention of the postnatal alveolar dysplasia induced by intrauterine hypoxia.

宫内缺氧是引起胎儿生长受限的常见原因。哺乳动物出生时肺脏肺泡化发育远未完成，各种不利于胎儿宫内发育的因素不仅将严重影响胎肺的正常发育，还将影响出生后肺泡的发育，导致成年期肺泡结构和功能的异常，是成年后肺部疾病发生的诱因。申请者基于前期初步研究结果，首次提出在整体和胎肺培养不同水平探讨谷氨酸NMDA受体激活在宫内缺氧对胎鼠出生后肺泡发育不良的影响，及过氧化物酶增殖体激活受体-γ(PPAR-γ)基因（为调控出生后肺泡发育的关键基因）表达下调发生中的作用，并进一步在DNA甲基化层面探讨PPAR-γ表达下调的表观遗传学机制及其意义，以初步揭示肺NMDA受体激活在宫内缺氧所致胎鼠出生后肺泡发育不良发生中的作用和分子机制。在整体、器官及分子水平论证谷氨酸通过激活NMDA受体是介导宫内低氧所致出生后肺泡发育不良的重要损伤因子的假说，为宫内缺氧所致出生后肺泡发育不良防治的研究提供新的思路。

本项目采用宫内缺氧所致大鼠出生时及生后至成年期肺泡发育不良模型及胎肺器官培养模型，首次发现宫内缺氧所致大鼠出生时的肺泡发育不良可持续至成年期，并首次证实NMDA受体拮抗剂美金刚胺可有效减轻宫内缺氧所致的大鼠出生时及出生后至成年期肺泡发育不良。在整体、胎肺器官培养、细胞分子及表观遗传学水平探讨NMDA受体过度激活在介导宫内缺氧所致大鼠出生时及生后至成年期肺泡发育不良发生中的重要作用，首次从分子水平发现NMDA受体拮抗剂美金刚胺可减轻宫内缺氧所致大鼠生后VEGF、TGF-β1基因表达水平的下降及PPAR-γ 基因表达水平的增高，并采用甲基化芯片、microRNA检测、表达谱芯片、亚硫酸氢盐处理后测序及焦磷酸测序等多种技术在表观遗传学水平发现NMDA受体拮抗剂美金刚胺可抑制宫内缺氧所致大鼠出生时肺组织TGF-β1甲基化增强，发挥其保护作用。并首次探讨出只有合适剂量和疗程的DNA甲基化酶抑制剂才对宫内缺氧所致生后肺泡发育不良具有保护作用，为宫内缺氧所致大鼠出生时及出生后至成年期肺泡发育不良的防治研究提供新的启示，有重要的应用前景。