Gansu Province Livestock Embryo Engineering Research Center, College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China.
College of Animal Husbandry and Verterinary Medicine, Southwest Minzu University, Chengdu, China.
Reprod Domest Anim. 2022 Apr;57(4):381-392. doi: 10.1111/rda.14076. Epub 2022 Jan 21.
The gas-phase environment of in vitro culture system plays an important role in the development of oocytes, and oxygen concentration is one of the important factors. In the present study, we aimed to explore the effect of different oxygen concentrations (20%, 10%, 5% or 1% O ) in yak oocyte maturation and to detect the expression of hypoxia-inducible factor 1α (HIF-1α), vascular endothelial growth factor (VEGF) and cell apoptosis in yak COCs. First, the maturation rate of oocytes, cleavage rate and blastocysts rate following parthenogenetic activation in the group with 5% oxygen concentration were significantly higher (p < .05) than the other groups. Then, TUNEL analysis showed that the 5% oxygen concentration group significantly inhibited apoptosis of cumulus-oocyte complexes (COCs) compared to the other group, and the transcription and protein levels of pro-apoptotic factor Bax, HIF-1α and VEGF in yak COCs significantly reduced, while anti-apoptotic factor Bcl-2 significantly increased. Furthermore, immunohistochemical staining results indicated that HIF-1α protein was mainly located in theca follicle interna, mural follicular stratum granulosum, corona radiata and ovarian stroma in the follicular ovarian tissue, while VEGF protein was mainly located in the granulosa and theca cell layers. In summary, our findings demonstrate that 5% oxygen concentration may promote maturation and inhibit apoptosis of oocytes through HIF-1α-mediated VEGF expression.
体外培养系统的气相环境对卵母细胞的发育起着重要作用，而氧浓度是其中的一个重要因素。本研究旨在探讨不同氧浓度（20%、10%、5%或 1% O ）对牦牛卵母细胞成熟的影响，并检测牦牛 COCs 中缺氧诱导因子 1α（HIF-1α）、血管内皮生长因子（VEGF）和细胞凋亡的表达。首先，在 5%氧浓度组，卵母细胞的成熟率、核分裂率和囊胚率显著高于其他组（p<.05）。然后，TUNEL 分析表明，与其他组相比，5%氧浓度组显著抑制了卵丘-卵母细胞复合物（COCs）的凋亡，牦牛 COCs 中促凋亡因子 Bax、HIF-1α 和 VEGF 的转录和蛋白水平显著降低，而抗凋亡因子 Bcl-2 显著增加。此外，免疫组化染色结果表明，HIF-1α 蛋白主要位于卵泡内膜层、卵泡壁层颗粒层、放射冠和卵巢基质中，而 VEGF 蛋白主要位于颗粒层和膜层细胞层。综上所述，我们的研究结果表明，5%氧浓度可能通过 HIF-1α 介导的 VEGF 表达促进卵母细胞成熟并抑制其凋亡。
