This study deals with the effect of plasminogen/plasmin on the in vitro maturation (IVM) of bovine cumulus‐oocyte complexes (COCs). Exogenous plasminogen activator streptokinase (SK) added to the IVM medium revealed similar values of cumulus expansion and oocyte nuclear maturation compared to controls (standard IVM medium). However, a decrease in both determinations was observed in COCs matured with the supplementation of ɛ‐aminocaproic acid (ɛ‐ACA), a specific plasmin inhibitor. After in vitro fertilization, no differences were observed in either cleavage or blastocyst rates between SK and control groups; however, ε‐ACA treatment caused a decrease in both developmental rates. Zona pellucida (ZP) digestion time decreased in the SK group while it increased in the ε‐ACA group. Raman microspectroscopy revealed an increase in the intensity of the band corresponding to the glycerol group of sialic acid in the ZP of oocytes matured with SK, whereas ZP spectra of oocytes treated with ɛ‐ACA presented similarities with immature oocytes. The results indicate that although treatment with SK did not alter oocyte developmental competence, it induced modifications in the ZP of oocytes that could modify the folding of glycoproteins. Plasmin inhibition impairs oocyte maturation and has an impact on embryo development, thus evidencing the importance of this protease during IVM.

中文翻译：

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牛卵丘-卵母细胞复合物体外成熟过程中纤溶酶原/纤溶酶活性的外源性激活和抑制：生物学和光谱学方法

本研究涉及纤溶酶原/纤溶酶对牛卵丘-卵母细胞复合物 (COC) 体外成熟 (IVM) 的影响。添加到 IVM 培养基中的外源性纤溶酶原激活剂链激酶 (SK) 显示与对照（标准 IVM 培养基）相比，卵丘扩张和卵母细胞核成熟的值相似。然而，在补充 ɛ-氨基己酸（ɛ-ACA）（一种特异性纤溶酶抑制剂）成熟的 COC 中观察到这两种测定值的降低。体外受精后，SK 组与对照组之间的卵裂率或囊胚率均未观察到差异；然而，ε-ACA 治疗导致两种发育率均下降。SK 组的透明带 (ZP) 消化时间减少，而 ε-ACA 组的消化时间增加。拉曼显微光谱显示，SK 成熟的卵母细胞 ZP 中唾液酸甘油基团对应的条带强度增加，而用 ɛ-ACA 处理的卵母细胞的 ZP 光谱显示出与未成熟卵母细胞的相似性。结果表明，虽然用 SK 处理不会改变卵母细胞的发育能力，但它会诱导卵母细胞 ZP 的修饰，从而改变糖蛋白的折叠。纤溶酶抑制会损害卵母细胞成熟并对胚胎发育产生影响，从而证明这种蛋白酶在 IVM 过程中的重要性。结果表明，虽然用 SK 处理不会改变卵母细胞的发育能力，但它会诱导卵母细胞 ZP 的修饰，从而改变糖蛋白的折叠。纤溶酶抑制会损害卵母细胞成熟并对胚胎发育产生影响，从而证明这种蛋白酶在 IVM 过程中的重要性。结果表明，虽然用 SK 处理不会改变卵母细胞的发育能力，但它会诱导卵母细胞 ZP 的修饰，从而改变糖蛋白的折叠。纤溶酶抑制会损害卵母细胞成熟并对胚胎发育产生影响，从而证明这种蛋白酶在 IVM 过程中的重要性。