Asimaki K, Vazakidou P, van Tol H T A, Oei C H Y, Modder E A, van Duursen M B M, Gadella B M
Division of Farm Animal Health, Department Population Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands.
Amsterdam Institute for Life and Environment, Section Environment and Health, Vrije Universiteit Amsterdam, Amsterdam, Netherlands.
Front Toxicol. 2022 May 24;4:811285. doi: 10.3389/ftox.2022.811285. eCollection 2022.
Endocrine disrupting chemicals (EDCs) can interfere with normal hormonal action and regulation. Exposure of women to EDCs has been associated with adverse reproductive health outcomes. The assays currently used to identify EDCs that elicit female reproductive toxicity lack screening tests that address effects on the maturation of oocytes, a process that enables them to be fertilized and develop into embryos. Here, a screening method employing the bovine model of oocyte maturation and embryo production is described. Endpoints explored address important events in oocyte maturation and developmental competence acquisition. To test the method, the effects of the known human EDC diethylstilbestrol (DES; an estrogen receptor agonist) were evaluated in a range of concentrations (10 M, 10 M, 10 M). Bovine oocytes were exposed to DES during maturation (IVM) or embryos were exposed during embryo culture (IVC). The endpoints evaluated included nuclear maturation, mitochondrial redistribution, cumulus cell expansion, apoptosis, and steroidogenesis. DES-exposed oocytes were fertilized to record embryo cleavage and blastocyst rates to uncover effects on developmental competence. Similarly, the development of embryos exposed to DES during IVC was monitored to assess the impact on early embryo development. Exposure to 10 M or 10 M DES did not affect the endpoints addressing oocyte maturation or embryo development. However, there were considerable detrimental effects observed in oocytes exposed to 10 M DES. Specifically, compared to vehicle-treated oocytes, there was a statistically significant reduction in nuclear maturation (3% vs 84%), cumulus expansion (2.8-fold vs 3.6-fold) and blastocyst rate (3% vs 32%). Additionally, progesterone and pregnenolone concentrations measured in IVM culture media were increased. The screening method described here shows that bovine oocytes were sensitive to the action of this particular chemical (i.e., DES), albeit at high concentrations. In principle, this method provides a valuable tool to assess the oocyte maturation process and early embryo development that can be used for reproductive toxicity screening and possibly EDC identification. Further studies should include EDCs with different mechanisms of action and additional endpoints to further demonstrate the applicability of the bovine oocyte model for chemical risk assessment purposes and EDC identification.
内分泌干扰化学物质(EDCs)会干扰正常的激素作用和调节。女性接触EDCs与不良生殖健康后果有关。目前用于识别引发女性生殖毒性的EDCs的检测方法缺乏针对卵母细胞成熟影响的筛查试验,而卵母细胞成熟是使其能够受精并发育成胚胎的过程。在此,描述了一种采用牛卵母细胞成熟和胚胎生产模型的筛查方法。所探索的终点涉及卵母细胞成熟和发育能力获得过程中的重要事件。为了测试该方法,在一系列浓度(10⁻⁹M、10⁻⁸M、10⁻⁷M)下评估了已知的人类EDC己烯雌酚(DES;一种雌激素受体激动剂)的作用。牛卵母细胞在体外成熟(IVM)期间暴露于DES,或胚胎在胚胎培养(IVC)期间暴露于DES。评估的终点包括核成熟、线粒体重新分布、卵丘细胞扩展、凋亡和类固醇生成。将暴露于DES的卵母细胞受精以记录胚胎分裂和囊胚率,以揭示对发育能力的影响。同样,监测IVC期间暴露于DES的胚胎的发育情况,以评估对早期胚胎发育的影响。暴露于10⁻⁹M或10⁻⁸M DES对涉及卵母细胞成熟或胚胎发育的终点没有影响。然而,在暴露于10⁻⁷M DES的卵母细胞中观察到了相当大的有害影响。具体而言,与载体处理的卵母细胞相比,核成熟(3%对84%)、卵丘扩展(2.8倍对3.6倍)和囊胚率(3%对32%)在统计学上有显著降低。此外,IVM培养基中测得的孕酮和孕烯醇酮浓度增加。这里描述的筛查方法表明,牛卵母细胞对这种特定化学物质(即DES)的作用敏感,尽管是在高浓度下。原则上,该方法为评估卵母细胞成熟过程和早期胚胎发育提供了一个有价值的工具,可用于生殖毒性筛查以及可能的EDC识别。进一步的研究应包括具有不同作用机制的EDCs和其他终点,以进一步证明牛卵母细胞模型在化学风险评估和EDC识别方面的适用性。