Department of Animal and Range Sciences, New Mexico State University, Las Cruces, NM, 88003, USA.
Department of Animal Science, University of California, Davis, CA, 95616, USA.
Theriogenology. 2024 Jan 15;214:57-65. doi: 10.1016/j.theriogenology.2023.10.010. Epub 2023 Oct 12.
Gram-negative bacteria release of lipopolysaccharide (LPS) endotoxin elicits robust immune responses capable of disrupting normal ovarian function contributing to female infertility. However, effects of subclinical or non-detectable infections on oocyte competence and subsequent embryo development remain to be fully elucidated. The aim of this study was to investigate the effects of exposing bovine oocytes to low LPS doses on oocyte and embryo competence. Bovine oocytes were collected from slaughterhouse-derived ovaries and matured with vehicle-control or increasing doses of LPS (0.01, 0.1, and 1 μg/mL) for 21 h. Oocytes (n = 252) were evaluated for nuclear maturation. A set of embryos from LPS-matured oocytes (n = 300) were cultured for 8 d to evaluate day 3 cleavage rates and day 8 blastocyst rates along with blastocyst cell counts. A subset of oocytes (n = 153) was fertilized and cultured for time-lapse image capture and analysis of embryo development. Results demonstrate no significant treatment differences among treatment groups in percent of oocytes at germinal vesicle (GV; P = 0.90), germinal vesicle breakdown (GVBD; P = 0.13), meiosis I (MI; P = 0.26), or metaphase II (MII; P = 0.44). Likewise, treatment differences were not observed in cleavage rates (P = 0.97), or blastocyst rates (P = 0.88) evaluated via traditional microscopy. Treatment with LPS did not affect total blastocyst cell count (P = 0.68), as indicated by trophectoderm (P = 0.83), and inner cell mass (P = 0.21) cell counts. Time-lapse embryo evaluation demonstrated no differences among control or LPS matured oocytes in number of zygotes that did not cleave after fertilization (P = 0.84), or those that cleaved but arrested at the 2-cell stage (P = 0.50), 4-cell (P = 0.76), prior to morula (P = 0.76). However, embryos derived from oocytes challenged with 0.1 μg/mL LPS tended to have reduced development to the morula stage compared with vehicle-treated controls (P = 0.06). Additionally, the percentage of blastocysts derived from oocytes matured in 0.01 μg/mL LPS tended to decrease compared to vehicle-treated controls (11.38 and 25.45 %, respectively; P = 0.09). Similarly, the proportion of oocytes that developed to the blastocyst stage was greater in vehicle-treated controls (25.45 %) compared with embryos derived from oocytes matured in 0.1 and 1 μg/mL (5.92 and 6.55 %, respectively; P = 0.03) LPS. These data suggest LPS-matured oocytes that subsequently underwent in vitro fertilization, experienced decreased competence to develop to the blastocyst stage.
革兰氏阴性菌释放的脂多糖 (LPS) 内毒素会引发强烈的免疫反应，破坏正常的卵巢功能，导致女性不孕。然而，亚临床或检测不到的感染对卵母细胞的能力和随后的胚胎发育的影响仍有待充分阐明。本研究旨在研究将低剂量 LPS 暴露于牛卵母细胞对卵母细胞和胚胎能力的影响。从屠宰场来源的卵巢中采集牛卵母细胞，并在载体对照或递增剂量的 LPS（0.01、0.1 和 1μg/mL）下成熟 21 小时。（n=252）评估卵母细胞的核成熟情况。一组来自 LPS 成熟卵母细胞的胚胎（n=300）进行培养 8 天，以评估第 3 天的卵裂率和第 8 天的囊胚率以及囊胚细胞计数。一部分卵母细胞（n=153）进行受精并进行延时图像采集和胚胎发育分析。结果表明，各组间卵母细胞在卵母细胞核（GV；P=0.90）、卵母细胞核破裂（GVBD；P=0.13）、第一次减数分裂（MI；P=0.26）或第二次减数分裂（MII；P=0.44）中的比例没有显著的处理差异。同样，通过传统显微镜评估的卵裂率（P=0.97）或囊胚率（P=0.88）也没有观察到处理差异。LPS 处理并未影响总囊胚细胞计数（P=0.68），如滋养外胚层（P=0.83）和内细胞团（P=0.21）细胞计数所示。延时胚胎评估显示，在受精后未发生卵裂的受精卵数量（P=0.84）或卵裂但在 2 细胞阶段停滞的受精卵数量（P=0.50）、4 细胞（P=0.76）、桑椹胚前（P=0.76）方面，对照或 LPS 成熟卵母细胞之间没有差异。然而，与载体处理的对照组相比，来自 0.1μg/mL LPS 处理卵母细胞的胚胎发育到桑椹胚阶段的趋势减少（P=0.06）。此外，与载体处理的对照组相比，来自 0.01μg/mL LPS 成熟卵母细胞的囊胚的比例呈下降趋势（分别为 11.38%和 25.45%；P=0.09）。同样，在载体处理的对照组中，发育到囊胚阶段的卵母细胞比例较高（25.45%），而来自 0.1 和 1μg/mL LPS 成熟卵母细胞的胚胎则较低（分别为 5.92%和 6.55%；P=0.03）。这些数据表明，随后进行体外受精的 LPS 成熟卵母细胞的能力下降，发育为囊胚阶段的能力降低。
