Effects of chronic hypoxia and AMPK activation on uteroplacental perfusion, placental metabolism and the regulation of fetal growth

项目摘要 高海拔（HA，>2500 m）缺氧使胎儿生长受限（FGR）的发生率增加3倍。 正常妊娠时，流入子宫胎盘循环（此处称为“子宫”）的血流量也减少 在高海拔或低海拔的FGR中，但子宫血流量降低并不是FGR的唯一原因，因为O2供应 仍然超过胎儿的氧气消耗量，即使在HA。因此，子宫血流量降低的机制 胎儿生长和它们的时间关系仍不清楚。我们之前的工作暗示AMPK参与了 子宫血管功能，血流和胎儿生长，我们的初步数据显示，FGR与适当的 在玻利维亚的拉巴斯（3850 m），妊娠期（阿加）妊娠的晚期子宫血流量较低; 胎盘AMPK活化程度更高，线粒体氧化代谢和代谢产物谱受到抑制 支持受损的脂肪酸和氨基酸代谢。我们建议人类和绵羊的研究 在慢性母体缺氧下进行，以确定 是否 胎盘AMPK信号传导作为一种 子宫胎盘灌注和胎盘代谢通过其双重作用调节胎儿生长之间的关系 作为一种有效的血管扩张剂和代谢传感器。在患有阿加或FGR妊娠的HA居民中， 我们将测量血流量，在胎盘两侧进行四血管取样， 采集胎盘和人子宫胎盘和胎儿胎盘动脉，调节血流，用于血管反应性 研究，并进行生化分析。由于FGR患者的血管舒张功能受损，我们将检测是否 药理学 介导 线粒体氧化代谢和氧化还原状态的调节剂恢复受损的AMPK- 血管舒张。由于只有在分娩时才能接触到人体血管和胎盘， 将在缺氧相关FGR的绵羊模型中进行平行研究，以测量这些相同的 变量，但也与代谢示踪剂之前和之后FGR（即在中期和晚期妊娠分别） 为了确定子宫O2供应何时减少，并测试O2供应、O2 消耗，营养吸收，和胎儿胎盘代谢相对于FGR的开始。就像人类 研究中，我们还将评估AMPK激活对子宫血管反应性和胎盘营养的影响。 代谢，并测试恢复线粒体氧化代谢是否改善关键子宫内膜的血管舒张。 抵抗船拟议的研究将使我们的理解超越传统的想法 胎儿氧合不足会触发FGR，我们知道何时以及如何与缺氧相关 FGR发育。这些信息对于改善治疗策略以恢复胎儿生长至关重要。 缺氧的条件下，一个目标，迄今为止，证明难以捉摸。

PROJECT SUMMARY The hypoxia of high-altitude (HA, >2500 m) increases the frequency of fetal growth restriction (FGR) three-fold. The normal pregnancy rise in blood flow to the uteroplacental circulation (termed “uterine” here) is also reduced in FGR at HA or at low altitude, but lower uterine blood flow is not solely responsible for FGR because O2 supply still exceeds fetal O2 consumption, even at HA. Thus, the mechanisms by which lower uterine blood flow reduces fetal growth and their temporal relationship remain unclear. Our prior work implicates AMPK in the regulation of uterine vascular function, blood flow, and fetal growth, and our preliminary data show that FGR vs. appropriate for gestational age (AGA) pregnancies in La Paz, Bolivia (3850 m) have lower third-trimester uterine blood flow; greater placental AMPK activation, suppressed mitochondrial oxidative metabolism, and metabolite profiles supporting impaired fatty acid and amino acid metabolism. We propose human and sheep studies to be conducted under chronic maternal hypoxia in order to determine whether placental AMPK signaling serves as a nexus between uteroplacental perfusion and placental metabolism to regulate fetal growth through its dual role as a potent vasodilator and metabolic sensor. In HA residents with AGA or FGR pregnancies women at unlabored C-section, we will measure blood flows, perform four-vessel sampling on both sides of the placenta, collect placental and human uteroplacental and fetoplacental arteries regulating blood flow for vasoreactivity studies, and conduct biochemical assays. Because vasodilation is impaired in FGR, we will test whether pharmacologic mediated modulators of mitochondrial oxidative metabolism and redox status restore impaired AMPK- vasorelaxation.Since access to human blood vessels and placenta are only available at delivery, we will perform parallel studies in a sheep model of hypoxia-associated FGR in order to measure these same variables but also with metabolic tracers both before and after FGR (i.e. at mid- and late-gestation respectively) in order to identify when uterine O2 supply decreases, and test the temporal relationship between O2 supply, O2 consumption, nutrient uptake, and fetoplacental metabolism relative to the initiation of FGR. As in the human studies, we will also assess the effects of AMPK activation on uterine vasoreactivity and placental nutrient metabolism, and test whether restoring mitochondrial oxidative metabolism improves vasodilation in key uterine resistance vessels. The proposed studies will enable our understanding to move beyond the conventional idea that insufficient fetal oxygenation triggers FGR to one in which we know when and how the hypoxia-associated FGR develops. Such information is essential for refining therapeutic strategies for restoring fetal growth under conditions of hypoxia, a goal that has, to date, proven elusive.