Biotechnology and Animal Reproduction Laboratory, Federal University of Santa Maria, Santa Maria, RS, Brazil.
Synthesis, Reactivity and Organocalcogens Pharmacological and Toxicological Assessment Laboratory, Federal University of Santa Maria, Santa Maria, RS, Brazil.
PLoS One. 2021 Sep 20;16(9):e0257418. doi: 10.1371/journal.pone.0257418. eCollection 2021.
One of the major causes of early pregnancy loss is heat stress. In ruminants, interferon tau (IFNT) is the embryo signal to the mother. Once the interferon signaling pathway is activated, it drives gene expression for interferon-stimulated genes (ISGs) and alters neutrophils responses. The aim of the present study was to evaluate interferon (IFN) pathway, ISGs and gene expression in polymorphonuclear leukocytes (PMN) and oxidative stress in dairy cows under heat stress. Pregnant cows had their estrous cycle synchronized and randomly assigned to a comfort or heat stress group. Blood samples were collected at artificial insemination (AI) and on Days 10, 14 and 18 following AI. Pregnant cows were pregnancy checked by ultrasound on Day 30 and confirmed on Day 60 post-AI. Results are presented as mean ± SEM. The corpus luteum (CL) diameter was not different between groups of pregnant cows; concentration of progesterone of pregnant cows on Day 18 following AI was greater in comfort group compared to heat stressed group. Comfort pregnant cows had higher expression of all analyzed genes from interferon pathway, except for IFNAR1, on both Days 14 and 18. Conversely, heat stressed cows did not show altered expression of IFNT pathway genes and ISGs between Days 10, 14, and 18 after AI. The oxidative stress, determined as malondialdehyde (MDA) levels, was greater in heat stress group on Days 10, 14 and 18, independent of pregnancy status. Heat stress negatively influences expression of ISGs, IFN pathway gene expression in neutrophils, and oxidative stress. Our data suggest that lower conception rates in cows under heat stress are multifactorial, with the association of interferon pathway activation and the unbalanced oxidative stress being main contributing factors.
导致早期妊娠丢失的一个主要原因是热应激。在反刍动物中，干扰素 tau（IFNT）是胚胎向母体发出的信号。一旦干扰素信号通路被激活，它就会驱动干扰素刺激基因（ISGs）的基因表达，并改变中性粒细胞的反应。本研究旨在评估热应激下奶牛的干扰素（IFN）通路、ISGs 和基因表达以及中性粒细胞中的氧化应激。妊娠奶牛的发情周期被同步，并随机分配到舒适或热应激组。在人工授精（AI）时和 AI 后第 10、14 和 18 天采集血液样本。妊娠奶牛在第 30 天通过超声检查妊娠情况，并在 AI 后第 60 天确认妊娠。结果以平均值±SEM 表示。黄体（CL）直径在两组妊娠奶牛之间没有差异；在 AI 后第 18 天，舒适组的妊娠奶牛的孕酮浓度高于热应激组。在 AI 后第 14 和 18 天，舒适组的所有分析基因的干扰素通路表达均高于热应激组，但 IFNAR1 除外。相反，热应激组的 IFNT 通路基因和 ISGs 的表达在 AI 后第 10、14 和 18 天之间没有改变。丙二醛（MDA）水平表示的氧化应激在热应激组在第 10、14 和 18 天均较高，与妊娠状态无关。热应激对中性粒细胞中 ISGs、IFN 通路基因表达和氧化应激的表达有负面影响。我们的数据表明，热应激下奶牛的受孕率较低是多因素的，与干扰素通路的激活和不平衡的氧化应激有关。
