Hashimoto S, Minami N, Takakura R, Yamada M, Imai H, Kashima N
Embryo Transplantation Laboratory, Snow Brand Milk Products Co. Ltd., Tomakomai, Hokkaido, Japan.
Mol Reprod Dev. 2000 Dec;57(4):353-60. doi: 10.1002/1098-2795(200012)57:4<353::AID-MRD7>3.0.CO;2-R.
The effects of carbohydrates on meiotic maturation and ATP content of bovine oocytes under low oxygen tension (5%) were investigated. Furthermore, the developmental competence or intracellular H(2)O(2) contents of the oocytes matured under 5% or 20% O(2) was assessed. In vitro maturation of bovine cumulus-oocyte complexes was performed in synthetic oviduct fluid (SOF) containing 20 amino acids and hormones (SOFaa). The proportion of the oocytes that matured to the metaphase II stage in SOFaa containing 1.5 mM glucose, 0.33 mM pyruvate, and 3.3 mM lactate under 5% O(2) was dramatically lower than that of oocytes matured under 20% O(2) (P < 0.01). Similarly, the ATP content of the oocytes that matured under 5% O(2) was much lower than that of oocytes matured under 20% O(2) (P < 0.05). Under 5% O(2) the proportion of metaphase II oocytes increased with increasing glucose concentration (0-20 mM) in SOFaa without pyruvate or lactate. In addition, the ATP content of oocytes cultured in 20 mM glucose was higher (P < 0.05) than that of oocytes cultured in 1. 5 mM glucose. Two glucose metabolites (pyruvate and lactate) and a nonmetabolizable glucose analog (2-deoxy-glucose), however, had no noticeable effects on meiotic maturation under 5% O(2). These results suggest that ATP production under 5% O(2) is not dependent on the TCA cycle. Addition of iodoacetate, a glycolytic inhibitor, to SOFaa containing 20 mM glucose significantly reduced (P < 0.01) the proportion of metaphase II and ATP content. Moreover, the proportion of the development to the blastocyst stage of oocytes matured under 5% O(2) was higher (P < 0.05) than that of oocytes matured under 20% O(2). H(2)O(2) contents of oocytes matured under 5% O(2) was lower (P < 0.05) than that of oocytes matured under 20% O(2). The results of the present study demonstrate that glucose plays important roles in supporting the completion of meiotic maturation in bovine cumulus-oocyte complexes under low oxygen tension and that low oxygen tension during in vitro maturation is beneficial for supporting the subsequent development of bovine oocytes.
研究了低氧张力（5%）下碳水化合物对牛卵母细胞减数分裂成熟和ATP含量的影响。此外，还评估了在5%或20%氧气条件下成熟的卵母细胞的发育能力或细胞内H₂O₂含量。牛卵丘-卵母细胞复合体在含有20种氨基酸和激素的合成输卵管液（SOFaa）中进行体外成熟培养。在5%氧气条件下，含有1.5 mM葡萄糖、0.33 mM丙酮酸和3.3 mM乳酸的SOFaa中成熟至中期II期的卵母细胞比例显著低于在20%氧气条件下成熟的卵母细胞（P < 0.01）。同样，在5%氧气条件下成熟的卵母细胞的ATP含量远低于在20%氧气条件下成熟的卵母细胞（P < 0.05）。在5%氧气条件下，不含丙酮酸或乳酸的SOFaa中，随着葡萄糖浓度（0 - 20 mM）的增加，中期II期卵母细胞的比例升高。此外，在20 mM葡萄糖中培养的卵母细胞的ATP含量高于在1.5 mM葡萄糖中培养的卵母细胞（P < 0.05）。然而，两种葡萄糖代谢物（丙酮酸和乳酸）以及一种不可代谢的葡萄糖类似物（2 - 脱氧葡萄糖）在5%氧气条件下对减数分裂成熟没有明显影响。这些结果表明，5%氧气条件下的ATP产生不依赖于三羧酸循环。向含有20 mM葡萄糖的SOFaa中添加糖酵解抑制剂碘乙酸显著降低了中期II期的比例和ATP含量（P < 0.01）。此外，在5%氧气条件下成熟的卵母细胞发育至囊胚阶段的比例高于在20%氧气条件下成熟的卵母细胞（P < 0.05）。在5%氧气条件下成熟的卵母细胞的H₂O₂含量低于在20%氧气条件下成熟的卵母细胞（P < 0.05）。本研究结果表明，葡萄糖在支持低氧张力下牛卵丘-卵母细胞复合体减数分裂成熟的完成中起重要作用，并且体外成熟过程中的低氧张力有利于支持牛卵母细胞的后续发育。
