Department of Animal Science, University of Tennessee, Knoxville, TN 37996, USA.
Department of Chemistry, University of Tennessee, Knoxville, TN 37996, USA.
J Anim Sci. 2022 Jul 1;100(7). doi: 10.1093/jas/skac136.
Cattle induced to ovulate a small, physiologically immature preovulatory follicle had reduced oocyte developmental competence that resulted in decreased embryo cleavage and day 7 embryo quality compared with animals induced to ovulate a more advanced follicle. RNA-sequencing was performed on oocytes and their corresponding cumulus cells approximately 23 h after gonadotropin-releasing hormone (GnRH) administration to induce the preovulatory gonadotropin surge suggested reduced capacity for glucose metabolism and oxidative phosphorylation in the cumulus cells and oocytes from follicles ≤11.7 mm, respectively. We hypothesized that induced ovulation of a small, physiologically immature preovulatory follicle results in a suboptimal follicular microenvironment and reduced oocyte metabolic capacity. We performed a study with the objective to determine the impact of preovulatory follicle diameter and serum estradiol concentration at GnRH administration on oocyte metabolic competence and follicular fluid metabolome profiles. We synchronized the development of a preovulatory follicle and collected the follicle contents via transvaginal aspiration approximately 19 h after GnRH administration in lactating beef cows (n = 319). We determined ATP levels and mitochondrial DNA (mtDNA) copy number in 110 oocytes and performed ultra-high-performance liquid chromatography-high resolution mass spectrometry metabolomic studies on 45 follicular fluid samples. Intraoocyte ATP and the amount of ATP produced per mtDNA copy number were associated with serum estradiol concentration at GnRH and time from GnRH administration to follicle aspiration (P < 0.05). mtDNA copy number was not related to follicle diameter at GnRH, serum estradiol concentration at GnRH, or any potential covariates (P > 0.10). We detected 90 metabolites in the aspirated follicular fluid. We identified 22 metabolites associated with serum estradiol concentration at GnRH and 63 metabolites associated with follicular fluid progesterone concentration at the time of follicle aspiration (FDR < 0.10). Pathway enrichment analysis of significant metabolites suggested altered proteinogenesis, citric acid cycle, and pyrimidine metabolism in follicles of reduced estrogenic capacity pre-gonadotropin surge or reduced progesterone production by the time of follicle aspiration.
用促性腺激素释放激素（GnRH）诱导排卵的小而生理不成熟的预排卵卵泡的牛的卵母细胞发育能力降低，与诱导排卵更大卵泡的动物相比，胚胎卵裂和第 7 天胚胎质量降低。大约在 GnRH 给药后 23 小时进行卵母细胞及其相应的卵丘细胞的 RNA 测序，以诱导促性腺激素释放的预排卵峰，提示卵丘细胞和卵泡中葡萄糖代谢和氧化磷酸化的能力分别降低 ≤11.7mm 的卵泡。我们假设，诱导小而生理不成熟的预排卵卵泡排卵会导致卵泡微环境不佳和卵母细胞代谢能力降低。我们进行了一项研究，目的是确定 GnRH 给药时预排卵卵泡直径和血清雌二醇浓度对卵母细胞代谢能力和卵泡液代谢组谱的影响。我们同步了预排卵卵泡的发育，并在 GnRH 给药后约 19 小时通过阴道超声抽吸收集卵泡内容物，在哺乳期肉牛（n = 319）中进行。我们测定了 110 个卵母细胞中的 ATP 水平和线粒体 DNA（mtDNA）拷贝数，并对 45 个卵泡液样本进行了超高效液相色谱-高分辨率质谱代谢组学研究。卵母细胞内的 ATP 及其每 mtDNA 拷贝数产生的 ATP 量与 GnRH 时的血清雌二醇浓度和 GnRH 至卵泡抽吸的时间有关（P < 0.05）。mtDNA 拷贝数与 GnRH 时的卵泡直径、GnRH 时的血清雌二醇浓度或任何潜在的协变量无关（P > 0.10）。我们在抽吸的卵泡液中检测到 90 种代谢物。我们确定了与 GnRH 时血清雌二醇浓度相关的 22 种代谢物和与卵泡液孕酮浓度相关的 63 种代谢物，这些代谢物在卵泡抽吸时（FDR < 0.10）。显著代谢物的通路富集分析表明，在促性腺激素峰前雌激素能力降低或卵泡抽吸时孕酮生成减少的卵泡中，蛋白质合成、柠檬酸循环和嘧啶代谢发生改变。
