Akazawa S, Unterman T, Metzger B E
First Department of Internal Medicine, Nagasaki University School of Medicine, Japan.
Metabolism. 1994 Jul;43(7):830-5. doi: 10.1016/0026-0495(94)90262-3.
Glucose metabolism provides an essential energy source in the mammalian embryo. We used the rat embryo culture system to investigate the activity of several critical pathways for glucose metabolism during early organogenesis, before (day 10 of gestation) and during (day 11) the establishment of the chorioallantoic circulation and closure of the neural tube. We studied glucose metabolism in the intact conceptus, the separated embryo, and its investing membranes, including the visceral yolk sac, allantois, and amnion. Short-term incubations were performed for 4 hours in culture media containing U-14C-, 14C-1-, or 14C-6-labeled D-glucose on day 10 and day 11 of gestation, and the rates of glucose utilization by glycolysis and oxidative metabolism, including the pentose phosphate pathway (PPP), were measured. Glycolytic metabolism, estimated by the accumulation of lactate, was high on day 10 in the intact conceptus, embryo, and membranes (92 +/- 6, 63 +/- 5, and 99 +/- 8 nmol/micrograms protein/4 h, respectively) and decreased by two thirds by day 11 in each tissue. Of note, the rate of glycolysis was greater in membranes than in the embryo on both days (P < .01). On the other hand, oxidative metabolism, reflected in the production of 14CO2, was relatively low on day 10 (0.78 +/- 0.04, 0.73 +/- 0.05, and 0.6 +/- 0.06 nmol/micrograms protein/4 h for intact conceptus, embryo, and membranes, respectively) and increased significantly in each tissue by day 11 (P < .01 for each).
葡萄糖代谢为哺乳动物胚胎提供了必需的能量来源。我们利用大鼠胚胎培养系统，研究了在早期器官发生过程中，即在绒毛膜尿囊循环建立和神经管闭合之前（妊娠第10天）和期间（妊娠第11天），葡萄糖代谢的几个关键途径的活性。我们研究了完整孕体、分离的胚胎及其附属膜（包括脏卵黄囊、尿囊和羊膜）中的葡萄糖代谢。在妊娠第10天和第11天，将胚胎在含有U-14C-、14C-1-或14C-6标记的D-葡萄糖的培养基中短期培养4小时，然后测量通过糖酵解和氧化代谢（包括磷酸戊糖途径（PPP））的葡萄糖利用率。通过乳酸积累估算的糖酵解代谢在妊娠第10天，完整孕体、胚胎和膜中较高（分别为92±6、63±5和99±8 nmol/μg蛋白质/4小时），并且在第11天每个组织中均下降了三分之二。值得注意的是，在这两天中，膜中的糖酵解速率均高于胚胎（P<.01）。另一方面，以14CO2产生反映的氧化代谢在第10天相对较低（完整孕体、胚胎和膜分别为0.78±0.04、0.73±0.05和0.6±0.06 nmol/μg蛋白质/4小时），并且在第11天每个组织中均显著增加（每个P<.01）。
