The regulation of early phase development of mammalian embryos

本研究旨在阐明小鼠胚胎在2细胞期（2细胞阻滞）后无法发育的机制。氟化钠（NaF，糖酵解中烯醇化酶的抑制剂）以剂量方式显著提高2细胞胚胎的进一步发育速率。在常规培养基中去除葡萄糖和磷酸盐可提高2细胞胚胎向* 3细胞的发育率（42%），而在不含葡萄糖和磷酸盐的培养基中添加2.5 mM的NaF可提高2细胞胚胎向* 3细胞的发育率（77%）。还考察了2.5 mM NaF对^<14>CO_2和[^<14 >c]乳酸生成形式[^<14 >c]葡萄糖的影响。2.5 mM NaF显著抑制[6-^<14>C]葡萄糖的^<14>CO_2和[^<14>C]乳酸生成，但对[1-^<14>C]-葡萄糖的^<14>CO_2生成没有影响，尽管它对胚胎对[^3H]脱氧- d -葡萄糖（一种非代谢的葡萄糖类似物）的摄取没有影响。在小鼠胚胎早期发育过程中，细胞内三磷酸腺苷（ATP）水平在卵裂前高于卵裂后。此外，在受精后30小时，未阻塞胚胎在第二次卵裂前的ATP水平明显高于阻塞胚胎。这些结果提示糖酵解过程中葡萄糖的流速可能调节2细胞胚胎向*3细胞的发育，细胞内ATP水平可能在体外小鼠胚胎早期发育中起关键作用。

This study was undertaken to elucidate the mechanism underlying the inability of mouse embryos to develop in culture past the 2-cell stage (2-cell block). Sodium fluoride (NaF, an inhibitor of enolase in glycolysis) significantly improved the rate of further development of 2-cell embryos in a dose-fashion manner. The removal of glucose and phosphate from the conventional medium improved the rate of development of 2-cell embryos to* 3 cell (42%), but the rate of development of 2-cell embryos to* 3 cells was enhanced (77%) when NaF at 2.5 mM was added to the medium without glucose and phosphate. The effect of NaF at 2.5 mM on ^<14>CO_2 and [^<14>C] lactate production form [^<14>C] glucose was also examined. NaF at 2.5 mM significantly inhibited both ^<14>CO_2 and [^<14>C] lactate production from [6-^<14>C] glucose, but not ^<14>CO_2 production from [1-^<14>C]-glucose, although it had no effect on the uptake of [^3H] deoxy-D-glucose (a non-metabolizable analogue of glucose) by the embryos. When the intracellular level of adenosine triphosphate (ATP) during early development of mouse embryos was examined, it was higher before rather than after cleavage. In addition, the ATP level was much higher before the 2nd cleavage 30 hr after insemination in unblocked embryos than that in blocked ones. These results suggest that the flow rate of glucose in glycolysis may regulate the development of 2-cell embryos to*3 cells, and that the intracellular level of ATP may be critical to early phase of mouse embryo development in vitro.