Hao Ruirong, Zhang Chunxiang, Lv Lihua, Shi Lei, Yue Wenbin
College of Animal Science and Technology, Shanxi Agricultural University, Taigu, PR China.
Theriogenology. 2013 Sep 15;80(5):436-42. doi: 10.1016/j.theriogenology.2013.05.005. Epub 2013 Jun 6.
Follicular fluid meiosis-activating sterol (FF-MAS), an intermediate in the cholesterol biosynthetic pathway, has been identified as a compound that induces the resumption of meiosis in mammalian oocyte. FF-MAS is converted to testis meiosis-activating sterol by a sterol Δ14-reductase. An inhibitor of Δ14-reductase and Δ7-reductase, AY9944 A-7, causes accumulation of FF-MAS by inhibiting its metabolism. The objective of this study was to determine the effects of AY9944 A-7 supplementation to oocyte maturation media on prepubertal sheep oocyte meiotic resumption and subsequent preimplantation development of embryos. Prepubertal sheep oocytes isolated at the germinal vesicle stage from their follicles were cultured with 0, 10, 20, 30, and 40 μM AY9944 A-7 for 24 hours in media with or without a meiotic inhibitor hypoxanthine (Hx, 4 mM). The resumption of meiosis was assessed by the frequency of germinal vesicle breakdown and the first polar body (PBI) extrusion. After maturation for 24 hours, oocytes with PBI were inseminated in vitro, and the percentages developing to the two-cell stage and blastocyst stage were measured as indicators of early embryonic developmental competence. AY9944 A-7 induced maturation of sheep cumulus-oocyte complexes with optimal concentrations of 10 and 20 μM both in Hx-inhibited meiotic maturation and spontaneous maturation, whereas AY9944 A-7 with any concentrations had no significant effect on that of denuded oocytes and split cumulus-oocyte complexes. Furthermore, maturing oocytes treated with either 10 or 20 μM AY9944 A-7 dramatically increased the percentages of ovine embryos developing to the two-cell stage and blastocyst stage. Higher concentrations of AY9944 A-7, 30 and 40 μM, were detrimental to oocytes and led to their degeneration. The present findings indicated for the first time that AY9944 A-7 was not only able to promote meiotic maturation, both Hx-inhibited and spontaneous, but also enhanced preimplantation developmental competence of prepubertal sheep oocytes maturing in vitro.
卵泡液减数分裂激活甾醇（FF-MAS）是胆固醇生物合成途径中的一种中间体，已被鉴定为一种能诱导哺乳动物卵母细胞恢复减数分裂的化合物。FF-MAS通过甾醇Δ14-还原酶转化为睾丸减数分裂激活甾醇。Δ14-还原酶和Δ7-还原酶的抑制剂AY9944 A-7通过抑制FF-MAS的代谢导致其积累。本研究的目的是确定向卵母细胞成熟培养基中添加AY9944 A-7对青春期前绵羊卵母细胞减数分裂恢复及随后胚胎植入前发育的影响。从卵泡中分离出的处于生发泡期的青春期前绵羊卵母细胞，在含有或不含有减数分裂抑制剂次黄嘌呤（Hx，4 mM）的培养基中，分别用0、10、20、30和40 μM的AY9944 A-7培养24小时。通过生发泡破裂频率和第一极体（PBⅠ）排出情况评估减数分裂的恢复。成熟24小时后，对排出PBⅠ的卵母细胞进行体外受精，并将发育到二细胞期和囊胚期的百分比作为早期胚胎发育能力的指标进行测定。在Hx抑制的减数分裂成熟和自发成熟过程中，AY9944 A-7在最佳浓度10和20 μM时均可诱导绵羊卵丘-卵母细胞复合体成熟，而任何浓度的AY9944 A-7对裸卵和分离的卵丘-卵母细胞复合体的成熟均无显著影响。此外，用10或20 μM AY9944 A-7处理成熟卵母细胞，显著提高了绵羊胚胎发育到二细胞期和囊胚期的百分比。较高浓度的AY9944 A-7（30和40 μM）对卵母细胞有害，导致其退化。本研究结果首次表明，AY9944 A-7不仅能够促进Hx抑制的减数分裂成熟和自发减数分裂成熟，还能提高体外成熟的青春期前绵羊卵母细胞的植入前发育能力。
