The wide use of graphene oxide (GO) has raised increasing concerns about the potential risks to environmental and human health. Recent studies have shown the vital role of gut microbiome in various pathological status or even exogenous exposure, but more detailed understanding about the effects of possible gut microbiome alterations under GO exposure on reproductive toxicology evaluations in pregnant mammals remained elusive. Here we found that orally administrated GO daily during gestational day (GD) 7–16 caused dose-dependent pregnant complications of mice on the endpoint (GD19), including decreased weight of dam and live fetus, high rate of resorbed embryos and dead fetus, and skeletal development retardation. Meanwhile in placenta tissues of pregnant mice exposed to GO at dose over 10 mg/kg, the expression levels of tight junctions (Claudin1 and Occludin) and vascular endothelial growth factor (VEGFA) decreased approximately by 30%–80%, meaning impaired placenta barrier. According to the data of fecal 16s RNA sequencing in 40 mg/kg dose group and the control group, gut microbiome showed dramatically decreased α- and β-diversity, and upregulated Firmicutes/Bacteroidetes ratio owing to GO exposure. What's more, significantly differentiated abundance of Euryarchaeota is expected to be a special biomarker for failed pregnancy caused by GO. Notably, the result of Spearman correlation analysis suggested that there was a strong link (correlation coefficient>0.6) between perturbed gut microbiome with both abnormally expressed factors of placenta barrier and adverse pregnant outcomes. In summary, the damages of GO exposure to placenta barrier and pregnancy were dose-dependent. And GO exposure was responsible for gut microbiome dysbiosis in mice with pregnant complications. These findings could provide referable evidence to evaluate reproductive risk of GO to mammals.

氧化石墨烯（GO）的广泛使用引起了人们越来越关注环境和人类健康的潜在风险。最近的研究表明，肠道微生物组在各种病理状态甚至外源性暴露中都起着至关重要的作用，但对于GO暴露下可能的肠道微生物组改变对怀孕哺乳动物生殖毒理学评估的影响的更详细的了解仍然难以捉摸。在这里，我们发现在妊娠日（GD）7-16期间每天口服GO会导致小鼠终点（GD19）的剂量依赖性妊娠并发症，包括水坝和活胎儿的体重减轻，高吸收率的胚胎和死胎，和骨骼发育迟缓。同时，在暴露于GO且剂量超过10 mg / kg的怀孕小鼠的胎盘组织中，紧密连接（Claudin1和Occludin）和血管内皮生长因子（VEGFA）的表达水平大约降低30％–80％，这意味着胎盘屏障受损。根据40 mg / kg剂量组和对照组粪便16s RNA测序的数据，肠道微生物组显示α-和β多样性显着降低，并上调由于接触GO而导致硬毛/拟杆菌比率。更重要的是，Euryarchaeota丰富的分化有望成为GO导致妊娠失败的特殊生物标记。值得注意的是，Spearman相关分析的结果表明，摄动的肠道微生物组与胎盘屏障的异常表达因子和不良妊娠结局之间存在很强的联系（相关系数> 0.6）。总之，GO暴露于胎盘屏障和妊娠的损害是剂量依赖性的。GO暴露是妊娠合并症小鼠肠道微生物组营养不良的原因。这些发现可为评估GO对哺乳动物的生殖风险提供参考。