Heat stress negatively affects reproductive functions in cows. Increased temperature disturbs fetal development in utero. However, the effect of heat stress on uterine endometrial tissues has not been fully examined. Using qPCR analysis, we measured the mRNA expression of various molecular markers in uterine endometrial tissue of dairy cows from Hokkaido, Japan, in winter and summer. Markers examined were heat shock proteins (HSPs), antioxidant enzymes (catalase, copper/zinc superoxide dismutase, manganese superoxide dismutase, and glutathione peroxidase 4), inflammatory cytokines, and interferon stimulated genes. Our results showed heat stress, body and milk temperatures were higher during summer than during winter. Expression levels of HSP27, HSP60, and HSP90 mRNA, and of catalase and copper/zinc superoxide dismutase mRNA were lower in summer than in winter. Tumor necrosis factor alpha expression was higher in summer than in winter. In conclusion, summer heat stress may reduce the expression of HSPs, affecting the levels of inflammatory cytokines in bovine uterine endometrial tissue.

中文翻译：

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夏季高温胁迫对牛子宫内膜组织基因表达的影响

热应激会对奶牛的生殖功能产生负面影响。温度升高会干扰胎儿在子宫内的发育。然而，热应激对子宫内膜组织的影响尚未得到充分研究。使用 qPCR 分析，我们测量了冬季和夏季日本北海道奶牛子宫内膜组织中各种分子标记的 mRNA 表达。检查的标志物是热休克蛋白 (HSP)、抗氧化酶（过氧化氢酶、铜/锌超氧化物歧化酶、锰超氧化物歧化酶和谷胱甘肽过氧化物酶 4）、炎症细胞因子和干扰素刺激基因。我们的结果表明夏季的热应激、身体和牛奶温度高于冬季。HSP27、HSP60和HSP90的表达水平mRNA、过氧化氢酶和铜/锌超氧化物歧化酶的mRNA在夏季低于冬季。夏季肿瘤坏死因子α表达高于冬季。综上所述，夏季热应激可能会降低HSPs的表达，从而影响牛子宫内膜组织中炎性细胞因子的水平。