Gopichandran N, Leese H J
Department of Biology (Area 3), University of York, PO Box 373, York YO10 5YW, UK.
Reproduction. 2003 Sep;126(3):299-308. doi: 10.1530/rep.0.1260299.
The formation of a viable blastocyst is dependent upon the establishment of a correct inner cell mass (ICM):trophectoderm cell ratio but little is known about the metabolism of the two cell populations or about the composition of blastocoel fluid. In this study, the metabolism of intact bovine blastocysts, isolated ICM and trophectoderm was examined in terms of glucose and pyruvate uptake, lactate production, and amino acid consumption or production. The concentration of these nutrients in blastocoel fluid was also determined. The metabolism of glucose, pyruvate and lactate differed significantly between the isolated ICM and trophectoderm. Isolated trophectoderm had a higher pyruvate (P<0.001) and lower glucose (P<0.05) consumption, and higher lactate production (P<0.05) than did ICM. The consumption or production of amino acids by ICM and trophectoderm also differed, with the trophectoderm displaying a higher turnover (the sum of production and consumption). The ICM and trophectoderm both depleted arginine, aspartate and leucine, whereas the production of alanine was consistent. Isolated ICM depleted a further six amino acids, which appeared during trophectoderm culture; the reverse trend was observed for the remaining amino acids. The concentration of lactate in blastocoel fluid was significantly higher than in synthetic oviductal fluid supplemented with amino acids and BSA (SOFaaBSA; P<0.05). However, glucose (P<0.05) and pyruvate (P<0.001) concentrations were both lower. Aspartate, glutamate, glycine, alanine and tryptophan were present at significantly higher concentrations in blastocoel fluid than in SOFaaBSA, whereas threonine and asparagine concentrations were significantly lower. The metabolism of composite blastocysts, obtained by summing the consumption and production profiles of the ICM and trophectoderm, and taking into account their respective number of cells, was higher than that of intact blastocysts, indicating that upon isolation of the two cell populations there may be disruption to paracrine interactions or the onset of culture-induced cellular stress or both.
有活力的囊胚的形成取决于正确的内细胞团（ICM）与滋养外胚层细胞比例的建立，但对于这两种细胞群体的代谢以及囊胚腔液的组成知之甚少。在本研究中，从葡萄糖和丙酮酸摄取、乳酸产生以及氨基酸消耗或产生方面检测了完整牛囊胚、分离的内细胞团和滋养外胚层的代谢。还测定了这些营养物质在囊胚腔液中的浓度。分离的内细胞团和滋养外胚层在葡萄糖、丙酮酸和乳酸代谢方面存在显著差异。与内细胞团相比，分离的滋养外胚层具有更高的丙酮酸消耗（P<0.001）和更低的葡萄糖消耗（P<0.05），以及更高的乳酸产生（P<0.05）。内细胞团和滋养外胚层的氨基酸消耗或产生也有所不同，滋养外胚层表现出更高的周转率（产生和消耗的总和）。内细胞团和滋养外胚层都消耗精氨酸、天冬氨酸和亮氨酸，而丙氨酸的产生是一致的。分离的内细胞团还消耗了另外六种氨基酸，这些氨基酸在滋养外胚层培养过程中出现；其余氨基酸则呈现相反趋势。囊胚腔液中乳酸的浓度显著高于添加了氨基酸和牛血清白蛋白的合成输卵管液（SOFaaBSA；P<0.05）。然而，葡萄糖（P<0.05）和丙酮酸（P<0.001）浓度均较低。天冬氨酸、谷氨酸、甘氨酸、丙氨酸和色氨酸在囊胚腔液中的浓度显著高于SOFaaBSA，而苏氨酸和天冬酰胺浓度则显著较低。通过汇总内细胞团和滋养外胚层的消耗和产生概况并考虑其各自的细胞数量而获得的复合囊胚的代谢高于完整囊胚，这表明在分离这两种细胞群体后，可能会破坏旁分泌相互作用或引发培养诱导的细胞应激或两者皆有。
