EFFECT OF HYPERGLYCEMIA ON NEURALATING MOUSE EMBRYOS

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 我们正在研究糖尿病妊娠导致出生缺陷的分子原因。我们以前已经表明，出生缺陷，发生在糖尿病患者比非糖尿病妊娠高3-5倍，是由胚胎的葡萄糖代谢增加引起的，这是由于母体循环向胚胎输送的葡萄糖增加。胚胎葡萄糖代谢的增加损害了结构发育所必需的基因的表达。在易受糖尿病妊娠引起的出生缺陷影响的发育阶段，胚胎尚未血管化，并存在于缺氧环境中（2-8% O2，而出生后动脉循环中的O2为20%）。因此，我们假设胚胎葡萄糖代谢的增加可能会比补充氧气更快地消耗氧气。这项研究与疾病有关，因为糖尿病胚胎病的生化和分子原因知之甚少，了解O2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 BioCurrents研究中心之前的研究中，我们发现母体高血糖3小时后，有氧代谢指标O2通量显著受到抑制。由于有氧代谢依赖于O2的可用性，抑制O2通量表明，与假设一致，过量的葡萄糖输送到胚胎导致O2消耗超过交付。我们已经获得了额外的证据表明，限制O2输送到胚胎在相同的发展阶段复制了母体糖尿病对胚胎发育的不利影响，支持这一假设，即增加葡萄糖代谢消耗O2的速度比它可以被补充。 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测定O2和葡萄糖通量，以进一步检验氧化葡萄糖代谢增加会消耗O2利用的假设。据我所知，没有其他资源可以提供这样的测量。鉴于我们位于马萨诸塞州波士顿的实验室与位于马萨诸塞州伍兹霍尔的BioCurrents实验室相邻，这是一个难得的机会来表征母体高血糖症诱导的O2和葡萄糖利用。 这些研究非常重要，不仅因为它们为糖尿病妊娠引起的出生缺陷的原因提供了生物化学见解，而且因为它们涉及代谢信号（即O2利用），激活发育控制途径。

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.