EFFECT OF HYPERGLYCEMIA ON NEURALATING MOUSE EMBRYOS

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 我们正在调查糖尿病妊娠导致出生缺陷的分子原因。我们以前已经证明，出生缺陷在糖尿病孕妇中发生的频率是非糖尿病孕妇的3-5倍，是由胚胎葡萄糖代谢增加引起的，这是葡萄糖从母体循环向胚胎输送增加的结果。胚胎增加的葡萄糖代谢会损害结构发育所必需的基因的表达。在易患糖尿病妊娠所致出生缺陷的发育阶段，胚胎还没有血管形成，处于低氧环境(2-8%O2，而出生后动脉循环中为20%O2)。因此，我们假设胚胎增加的葡萄糖代谢消耗氧气的速度可能快于补充氧气的速度。这项研究与疾病相关，因为糖尿病胚胎病变的生化和分子原因知之甚少，了解氧气消耗是否有助于这种糖尿病并发症的发病机制可能会导致预防它的治疗。 在NCRR生物电流研究中心之前的研究中，我们发现，在母亲高血糖3小时后，氧通量-有氧代谢的指标-显著受到抑制。由于有氧代谢依赖于氧气的可获得性，抑制氧气通量表明，与假设一致，过量的葡萄糖输送到胚胎导致氧气消耗超过输送。我们获得了更多的证据，表明在同一发育阶段限制氧气输送到胚胎会复制母体糖尿病对胚胎发育的不利影响，支持了葡萄糖代谢增加消耗氧气的速度快于其可以复制的假说。 在未来的实验中，我们建议在诱导母体高血糖后的快速时间点检测O2和葡萄糖通量，以进一步验证氧化葡萄糖代谢增加耗尽O2利用率的假设。据我所知，没有其他资源可以提供这样的测量。鉴于我们在马萨诸塞州波士顿的实验室距离马萨诸塞州伍兹霍尔的BioCurrents实验室很近，这是一个难得的机会来表征母体高血糖诱导的O2和葡萄糖利用。 这些研究具有非常重要的意义，不仅因为它们为糖尿病妊娠导致出生缺陷的原因提供了生化见解，而且还因为它们涉及到代谢信号(即氧气利用)在发育控制途径的激活中。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We are investigating the molecular causes of birth defects induced by diabetic pregnancy. We have previously shown that birth defects, which occur 3-5 times more frequently in diabetic, than in nondiabetic pregnancies, are caused by increased glucose metabolism by the embryo, resulting from increased delivery of glucose from maternal circulation to the embryo. Increased glucose metabolism by the embryo impairs expression of genes which are necessary for structural development. At the stage of development that is susceptible to diabetic pregnancy-induced birth defects, the embryo is not yet vascularized and exists in a hypoxic environment (2-8% O2, compared to 20% O2 in post-natal arterial circulation). Thus, we hypothesized that increased glucose metabolism by the embryo could consume O2 faster than it could be replenished. This research has relevance to disease, because the biochemical and molecular causes of diabetic embryopathy are poorly understood, and understanding whether O2 consumption contributes to the pathogenesis of this diabetic complication may lead to therapies to prevent it. In prior studies at the NCRR BioCurrents Research Center, we found that after 3 hours of maternal hyperglycemia, O2 flux, an indicator of aerobic metabolism, was significantly suppressed. Since aerobic metabolism depends on O2 availability, suppression of O2 flux indicates that, consistent with the hypothesis, excess glucose delivery to the embryo led to O2 consumption in excess of delivery. We have obtained additional evidence that restricting O2 delivery to embryos at the same stage of development replicates the adverse effects of maternal diabetes on embryogenesis, supporting the hypothesis that increased glucose metabolism consumes O2 faster than it can be repleted. In future experiments, we propose to assay O2 and glucose flux at rapid time points after induction of maternal hyperglycemia, to further test the hypothesis that increased oxidative glucose metabolism depletes O2 utilization. There is no other resource that I know of which can provide such measurements. Given the proximity of our laboratory in Boston, MA, to the BioCurrents Laboratory in Woods Hole, MA, this is a rare opportunity to characterize maternal hyperglycemia-induced O2 and glucose utilization. These studies are highly significant, not only because they provide biochemical insights into the causes of birth defects induced by diabetic pregnancy, but because they implicate metabolic signaling (i.e. O2 utilization), in activation of developmental control pathways.