Silva C C, Knight P G
School of Animal and Microbial Sciences, The University of Reading, Whiteknights, United Kingdom.
Biol Reprod. 1998 Feb;58(2):558-65. doi: 10.1095/biolreprod58.2.558.
The presence of activin receptors on oocytes and granulosa cells suggests that activin and its binding protein, follistatin, may regulate oocyte maturation. The aim of the present study was to investigate whether activin-A and follistatin can influence the in vitro maturation of bovine oocytes as assessed by their competence to form blastocysts after in vitro fertilization. Bovine cumulus oocyte complexes (COCs) were cultured for 22-24 h at 38.5 degrees C in tissue culture medium-199 supplemented with 10% estrous cow serum, eCG (2.5 IU/ml), and either no treatment (control), activin-A (0.1 or 0.5 microg/ml), follistatin (0.1, 1, or 10 microg/ml), or activin-A (0.5 microg/ml) in combination with follistatin (0.5 or 5 microg/ml). In separate experiments, the same treatments were also tested on cumulus-free oocytes, which had a much reduced developmental capacity when compared to COCs. Neither activin-A nor follistatin affected the postfertilization cleavage rate of either COCs (approximately 60%) or cumulus-free oocytes (approximately 40%). Activin increased (p < 0.05) the proportion of cleaved oocytes that reached the blastocyst stage when added to both COCs (38% increase) and cumulus-free oocytes (160% increase), with the magnitude of response much greater with the latter. Follistatin had a dose-dependent inhibitory effect on blastocyst yield from COCs (67% reduction, p < 0.05) and opposed the stimulatory effect of activin (p < 0.05). With cumulus-free oocytes, however, follistatin did not further decrease the low developmental potential of oocytes. A positive correlation (r = 0.57, p < 0.001) was found between endogenous levels of activin-A produced by COCs and their postcleavage development to the blastocyst stage. No such correlation was found between endogenous follistatin level and postcleavage development (r = 0.10, p = 0.46). Endogenous levels of activin-A and follistatin secreted by cumulus-free oocytes were undetectable. These in vitro observations support the hypothesis that activin-A and follistatin, both secretory products of cumulus cells, contribute to the regulation of oocyte maturation in vivo.
卵母细胞和颗粒细胞上存在激活素受体，这表明激活素及其结合蛋白卵泡抑素可能调节卵母细胞成熟。本研究的目的是调查激活素A和卵泡抑素是否会影响牛卵母细胞的体外成熟，这通过体外受精后它们形成囊胚的能力来评估。将牛卵丘卵母细胞复合体（COCs）在38.5℃下于添加了10%发情母牛血清、eCG（2.5IU/ml）且无处理（对照）、激活素A（0.1或0.5μg/ml）、卵泡抑素（0.1、1或10μg/ml）或激活素A（0.5μg/ml）与卵泡抑素（0.5或5μg/ml）组合的组织培养液-199中培养22 - 24小时。在单独的实验中，对裸卵也进行了相同处理，与COCs相比，裸卵的发育能力大大降低。激活素A和卵泡抑素均未影响COCs（约60%）或裸卵（约40%）的受精后卵裂率。当添加到COCs（增加38%）和裸卵（增加160%）中时，激活素增加了（p < 0.05）达到囊胚阶段的卵裂卵比例，后者的反应幅度更大。卵泡抑素对COCs的囊胚产量有剂量依赖性抑制作用（降低67%，p < 0.05），并对抗激活素的刺激作用（p < 0.05）。然而，对于裸卵，卵泡抑素并未进一步降低卵母细胞的低发育潜能。发现COCs产生的内源性激活素A水平与其卵裂后发育到囊胚阶段之间存在正相关（r = 0.57，p < 0.001）。在内源性卵泡抑素水平与卵裂后发育之间未发现这种相关性（r = 0.10，p = 0.46）。未检测到裸卵分泌的内源性激活素A和卵泡抑素水平。这些体外观察结果支持以下假设：激活素A和卵泡抑素均为卵丘细胞的分泌产物，在体内有助于调节卵母细胞成熟。
