丁内酯-Ⅰ对小鼠卵母细胞体外成熟的影响

Effect of Butyrolactone-Ⅰ on Maturation in vitro in Murine Oocytes

目的研究丁内酯Ⅰ(BLⅠ)对小鼠卵母细胞体外成熟及成熟动力学的影响。方法以BLⅠ作为成熟抑制剂,按“两步法”培养小鼠卵丘卵母细胞复合物(COC),即先用含有不同浓度BLⅠ(0、6.25、12.5、25、0、100μmol/L)的培养液培养,按培养时间分为3h组和6h组。BLⅠ培养液培养结束时,观察卵母细胞生发泡破裂(GVBD)的发生率,再用不含BLⅠ的培养液继续培养,进一步观察其成熟动力学的变化,即卵母细胞GVBD过程和第一极体形成过程。结果6.25μmol/L及以上浓度的BL I培养液均可将未成熟卵的GVBD抑制3h,抑制6h则需100μmol/LBLⅠ。BLⅠ抑制作用解除后,卵母细胞的成熟率与对照组的差异无显著性意义(P>0.05),但卵母细胞的成熟动力学发生明显改变,GVBD和成熟过程较对照组明显加速。结论BLⅠ对小鼠未成熟卵GVBD3h或6h的抑制是可逆的,不影响小鼠卵母细胞的成熟能力,但成熟动力学发生明显改变。而这可能改善体外成熟的卵母细胞胞质成熟滞后于核成熟的状态,提高未成熟卵的发育能力。

Objective To study the effect of butyrolactone-Ⅰ（BL-Ⅰ） on maturation in vitro and the kinetics of meiotic maturation in murine cumulus oocyte complex. Methods Murine immature oocytes cultured in the media containing different concentrations of BL-Ⅰ（0, 6.25, 12.5, 25, 50, 100μmol/L） were divided into two groups. In one group oocytes were cultured for 3h and in the other one for 6h. Incidence of germinal vesicle breakdown （GVBD） was observed following the culture with BL-Ⅰ. Then oocytes were continuously cultured in the maturation media without BL-Ⅰ to observe GVBD and the first polar body extrusion. Results The media in the presence of ≥6.25μmol/L BL-Ⅰ could inhibit GVBD of immature oocytes for 3 h, and the media in the presence of 100μmol/L BL-Ⅰ could inhibit it for 6h. Maturation rates of both groups were similar, but the timing of GVBD and the first polar body extrusion were accelerated in murine oocytes following the withdrawal of BL-Ⅰ, especially oocytes in 100μmol/L BL-Ⅰ group. Conclusion The BL-Ⅰ induced block of GVBD for 3h or 6h was reversible and mature competence of the murine oocytes was not affected in the sequent culture, hut the kinetics of meiotic maturation was accelerated following the withdrawal of BL-Ⅰ, The change of the kinetics of meiotic maturation might improve maturation of ooplasm, which may increase development competence in murine oocytes.