Stress and infection seriously threaten the reproductive performance and health of dairy cows. Various perinatal stresses increase plasma cortisol concentrations in cows, and chronically high cortisol levels may increase the incidence and severity of the uterine diseases. Selenium (Se) enhances antioxidant capacity of cows. The aim of this study was to explore how Se affects the oxidative stress of primary bovine endometrial stromal cells (BESC) with high cortisol background. The levels of reactive oxygen species (ROS) and other biomarkers of oxidative stress were measured using flow cytometry and assay kits. The changes in nuclear NF-E2-related factor 2 (Nrf2) pathway were detected by Western blot, qPCR, and immunofluorescence. The result showed that lipopolysaccharide (LPS) increased (P < 0.01) ROS and malondialdehyde (MDA) content and reduced (P < 0.01) superoxide dismutase (SOD) concentration, provoking BESC oxidative stress. The elevated levels of cortisol resulted in the accumulation (P < 0.05) of ROS and MDA and inhibition (P < 0.05) of SOD in unstimulated BESC but demonstrated an antioxidative effect in LPS-stimulated cells. Pretreatment with Se reduced (P < 0.01) the levels of ROS and MDA, while increasing (P < 0.05) the antioxidant capacities and the relative abundance of gene transcripts and proteins related to the Nrf2 pathway in BESC. This antioxidant effect was more pronounced in the presence of high cortisol level. In conclusion, cortisol alone induced the oxidative damage but provided an antioxidant protection in the presence of LPS. Se alleviated the LPS-induced cellular oxidative stress, which is probably achieved through activating Nrf2 pathway. At high cortisol levels, Se supplement has a more significant protective effect on BESC oxidative stress. This study provided evidence for the protective role of Se in bovine endometrial oxidative damage of stressed animals and suggested the potential regulatory mechanism in vitro.

中文翻译：

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硒通过具有高皮质醇背景的 Nrf2 通路抑制 LPS 诱导的牛子宫内膜基质细胞氧化应激


压力和感染严重威胁着奶牛的繁殖性能和健康。各种围产期应激会增加奶牛血浆皮质醇浓度，长期高皮质醇水平可能会增加子宫疾病的发病率和严重程度。硒 （Se） 可增强奶牛的抗氧化能力。本研究的目的是探讨 Se 如何影响具有高皮质醇背景的原代牛子宫内膜基质细胞 （BESC） 的氧化应激。使用流式细胞术和检测试剂盒测量活性氧 （ROS） 和其他氧化应激生物标志物的水平。Western blot、qPCR 和免疫荧光检测核 NF-E2 相关因子 2 （Nrf2） 通路的变化。结果表明，脂多糖 （LPS） 增加了 （P < 0.01） ROS 和丙二醛 （MDA） 含量，降低了 （P < 0.01） 超氧化物歧化酶 （SOD） 浓度，引发了 BESC 氧化应激。皮质醇水平升高导致未刺激的 BESC 中 ROS 和 MDA 的积累 （P < 0.05） 和 SOD 的抑制 （P < 0.05），但在 LPS 刺激的细胞中表现出抗氧化作用。用 Se 预处理降低了 （P < 0.01） ROS 和 MDA 的水平，同时增加了 （P < 0.05） BESC 中与 Nrf2 通路相关的基因转录本和蛋白质的抗氧化能力和相对丰度。这种抗氧化作用在皮质醇水平高的情况下更为明显。总之，单独使用皮质醇会诱导氧化损伤，但在 LPS 存在下提供抗氧化保护。Se 减轻了 LPS 诱导的细胞氧化应激，这可能是通过激活 Nrf2 通路实现的。 在高皮质醇水平下，Se 补充剂对 BESC 氧化应激具有更显着的保护作用。本研究为 Se 在应激动物牛子宫内膜氧化损伤中的保护作用提供了证据，并提出了潜在的体外调节机制。