组织型纤溶酶原激活剂基因在牛卵丘—卵母复合体体外成熟进程中的表达

摘要

In the present study,four experiments were conducted to investigate the potential effects of tPA on bovine cumulus and oocytes during in vitro maturation (IVM) (0,8,16,24 h). The expressions of tPA were detected by relative Real-time RT-PCR experiments in bovine cumulus and oocytes both after 0,8,16,24 h of IVM and under different FSH concentrations after 16 h of IVM separately. Meanwhile,the degree of bovine cumulus cell expansion and the percentages of first polar body in oocyte were assessed respectively. TPA mRNA levels were higher in cumulus and oocytes at 16 h and 24 h than those at 0 h and 8 h of IVM significantly (P<0. 05). Among those groups that under different FSH concentrations (0,0. 01,0. 1 and 1 IU/mL) after 16 h of IVM.tPA mRNA levels of cumulus was increased following the elevated FSH concentrations,as well as the cumulus expansion,tPA mRNA of cumulus cells in 1 IU/mL FSH group was significantly higher than others. The results indicated that the expression of tPA in bovine cumulus was regulated positively by FSH.tPA could facilitate the cumulus expansion during IVM. However.it needed to be further investigated that tPA expression might be involved in first polar body excrusion of bovine oocytes.%为了初步了解组织型纤溶酶原激活剂( tissue-plasminogen activator,tPA)在牛卵丘—卵母复合体体外成熟进程中的潜在作用,试验运用实时定量RT-PCR技术分别检测体外成熟过程中不同时间段(0、8、16、24 h)以及添加不同浓度FSH成熟培养16 h后的牛卵丘细胞和卵母细胞中tPA基因相对表达变化,观察添加不同浓度FSH成熟培养16h后卵丘细胞膨胀程度差异,并统计卵母细胞第一极体排出情况.结果显示,卵丘—卵母复合体在体外成熟初期,tPA mRNA相对表达水平在体外成熟16和24 h的卵丘细胞和卵母细胞中显著高于0和8h组；在添加不同浓度FSH(0、0.01、0.1和1 IU/mL)体外成熟16h的各处理组,卵丘细胞中tPA mRNA相对表达量随FSH添加浓度的升高而升高,卵丘细胞的扩散程度亦随之增加；同时tPA mRNA相对表达量在0.01 IU/mL FSH添加组卵母细胞中显著高于其他各FSH添加组.综合以上研究结果,本研究认为,牛卵丘细胞中tPA基因的表达受FSH正向调节；tPA可能促进了卵丘细胞在体外成熟过程中的扩散；同时,tPA在卵母细胞中的表达是否与其第一极体排出有关,需进一步试验验证.