Centre de recherche en Reproduction, Développement et Santé Intergénérationnelle, Faculté des Sciences de l'Agriculture et de l'Alimentation, Département des Sciences Animales, Université Laval, Québec, QC G1V 0A6, Canada.
L'Alliance Boviteq, Saint-Hyacinthe, QC, Canada.
Domest Anim Endocrinol. 2020 Jul;72:106429. doi: 10.1016/j.domaniend.2019.106429. Epub 2019 Dec 26.
Cumulus cells have an important role to play in the final preparation of the oocyte before ovulation. During the final phase of follicular differentiation, FSH levels are low and LH maintains follicular growth; however, it is not known if at that time LH has an influence on cumulus cells inside the follicle. In humans, LH is often inhibited to avoid a premature ovulatory LH surge. This procedure provides a tool to investigate the role of LH in follicular development. In this study, we investigated the impact of suppressing LH using the GnRH antagonist cetrorelix during an ovarian coasting stimulation protocol on the transcriptome of bovine cumulus cells (CC). Oocytes were collected twice from 6 dairy cows. For the first collection, the cows received FSH twice daily for 3 d, followed by FSH withdrawal for 68 h as a control protocol. For the second collection, the same stimulation protocol was used, but the cows also received, starting on day 2 of FSH stimulation, a GnRH antagonist once a day until recovery of the cumulus-oocyte complexes (COC). Half of the COC were subjected to in vitro maturation, fertilization, and culture to assess blastocyst rates. The other half of the COC underwent microarray analysis (n = 3 cows, 2 treatments, 6 oocyte collections) and qRT-PCR (n = 6 cows: 3 microarray cows +3 other cows, 2 treatments, 12 oocyte collections). The differential expression of specific genes was confirmed by RT-qPCR: decrease of ATP6AP2, SC4MOL, and OSTC and increase of PTGDS in the LH-inhibited condition. The global transcriptomic analysis of cumulus cells demonstrated that the inhibition of LH secretion may decrease survival and growth of the follicle. Moreover, the results suggested that LH may be important to cumulus for the maintenance of cellular mechanisms such as global RNA expression, protein and nucleic acid metabolism, and energy production. These results support the hypothesis that LH support is important during the final part of follicle maturation through its influence on the cumulus cells.
卵丘细胞在排卵前卵母细胞的最终准备中起着重要作用。在卵泡分化的最后阶段，FSH 水平较低，而 LH 维持卵泡生长；然而，尚不清楚此时 LH 是否对卵泡内的卵丘细胞有影响。在人类中，LH 通常被抑制以避免过早的排卵 LH 激增。该程序提供了一种工具来研究 LH 在卵泡发育中的作用。在这项研究中，我们研究了在卵巢滑行刺激方案中使用 GnRH 拮抗剂 cetrorelix 抑制 LH 对牛卵丘细胞 (CC) 转录组的影响。从 6 头奶牛中两次采集卵母细胞。第一次采集时，奶牛每天接受 FSH 两次，持续 3 天，然后 FSH 撤药 68 小时作为对照方案。第二次采集时，使用相同的刺激方案，但奶牛从 FSH 刺激的第 2 天开始，每天接受一次 GnRH 拮抗剂，直到卵丘-卵母细胞复合物 (COC) 恢复。一半的 COC 进行体外成熟、受精和培养，以评估囊胚率。另一半 COC 进行微阵列分析（n = 3 头奶牛，2 种处理，6 个卵母细胞采集）和 qRT-PCR（n = 6 头奶牛：3 个微阵列奶牛+3 个其他奶牛，2 种处理，12 个卵母细胞采集）。通过 RT-qPCR 证实了特定基因的差异表达：在 LH 抑制条件下，ATP6AP2、SC4MOL 和 OSTC 减少，PTGDS 增加。卵丘细胞的全转录组分析表明，LH 分泌的抑制可能会降低卵泡的存活和生长。此外，结果表明 LH 可能对卵丘细胞维持细胞机制（如全局 RNA 表达、蛋白质和核酸代谢以及能量产生）很重要。这些结果支持了这样的假设，即 LH 支持在卵泡成熟的最后阶段通过对卵丘细胞的影响是很重要的。
