Dellaqua Thaisy Tino, Vígaro Renan Aparecido, Janini Ludimila Cardoso Zoccal, Dal Canto Mariabeatrice, Renzini Mario Mignini, Lodde Valentina, Luciano Alberto Maria, Buratini Jose
Department of Structural and Functional Biology, Institute of Biosciences, Sao Paulo State University, Botucatu, Sao Paulo, Brazil.
Department of Veterinary Surgery and Animal Reproduction, School of Veterinary Medicine and Animal Science, Sao Paulo State University, Botucatu, Sao Paulo, Brazil.
Theriogenology. 2023 Jan 1;195:209-216. doi: 10.1016/j.theriogenology.2022.10.041. Epub 2022 Nov 3.
Oocyte in vitro maturation (IVM) is still a major challenge in human and animal assisted reproduction. Gradual instead of abrupt activation of the ovulatory cascade during IVM has been proposed to enhance nuclear-cytoplasmic synchrony and cumulus-oocyte communication, thus favoring oocyte developmental competence. Herein, we assessed the effects of neuregulin 1 (NRG1), an EGF-like factor that modulates EGFR signaling, on oocyte nuclear maturation dynamics, cumulus expansion and expression of mRNAs regulating these processes during IVM, as well as on post-IVF embryo development following AREG-stimulated IVM in cattle. In experiment 1, cumulus-oocyte complexes (COCs) were subjected to IVM with graded doses of NRG1 (1, 10 or 100 ng/mL) for 6, 9, 12, 20, and 24 h, after which oocyte nuclear status and cumulus mRNA expression were assessed. At 6 h of IVM, NRG1 at 1 ng/mL significantly decreased the percentage of GVBD (germinal vesicle breakdown) oocytes without altering later meiotic dynamics or the percentage of oocytes achieving meiosis II. In experiment 2, adding NRG1 (1 ng/mL) to the IVM medium did not affect cumulus expansion but increased the percentage of expanded and hatched blastocysts, and blastocyst total cell number following IVF/IVC. NRG1 decreased EGFR mRNA abundance while increasing NPR2 and PTX3 mRNA levels at 9 h, and TNFAIP6 mRNA abundance at 20 h of IVM. This is the first study that reports the modulatory effect of NGR1 during oocyte maturation in a mono-ovulatory species and demonstrates that this action may be applied during IVM to improve post-IVF embryo development.
卵母细胞体外成熟（IVM）仍是人类和动物辅助生殖中的一项重大挑战。有人提出，在IVM过程中逐步而非突然激活排卵级联反应，以增强核质同步性和卵丘-卵母细胞间通讯，从而有利于卵母细胞的发育能力。在此，我们评估了神经调节蛋白1（NRG1，一种调节表皮生长因子受体（EGFR）信号传导的表皮生长因子样因子）对IVM过程中卵母细胞核成熟动力学、卵丘扩展以及调节这些过程的mRNA表达的影响，以及对牛在双调蛋白（AREG）刺激的IVM后体外受精（IVF）胚胎发育的影响。在实验1中，将卵丘-卵母细胞复合体（COCs）用不同剂量（1、10或100 ng/mL）的NRG1进行IVM处理6、9、12、20和24小时，之后评估卵母细胞核状态和卵丘mRNA表达。在IVM 6小时时，1 ng/mL的NRG1显著降低了生发泡破裂（GVBD）卵母细胞的比例，同时不改变后续减数分裂动力学或达到减数分裂II期的卵母细胞比例。在实验2中，向IVM培养基中添加NRG1（1 ng/mL）不影响卵丘扩展，但增加了IVF/IVC后扩张和孵化囊胚的比例以及囊胚总细胞数。在IVM 9小时时，NRG1降低了EGFR mRNA丰度，同时增加了 NPR2和PTX3 mRNA水平，在IVM 20小时时增加了TNFAIP6 mRNA丰度。这是第一项报道NRG1在单排卵物种卵母细胞成熟过程中调节作用的研究，并证明这种作用可在IVM期间应用以改善IVF后胚胎发育。
