[Objective]Effect of heat stress on rumen epithelial cell barrier permeability in dairy goat were studied in order to provide a rational and experimental basis for animals in hot environments to maintain normal physiological function and to explore methods of resistance to heat stress. [Method]Effect of heat stress on the concentration of D-lactic acid, DAO, endotoxin and inflammatory cytokines of blood serum, and the expression of tight junction protein occludin were studied with mid-or late-lactation dairy goats by molecular biology method in this project. [Result] Heat stress significantly increased the concentration of D-lactic acid, DAO of blood serum. Heat stress significantly increased the concentration of endotoxin and inflammatory cytokines, such as TNF-α, IL-1α, IL-6, IL-1β and interferon-γ. Heat stress damaged the tight junction structure between rumen epithelial, and significantly reduced the proteins expression and mRNA expression of occludin protein in tight junction. [Conclusion] The mechanisms of the damage of rumen mucous membrane barrier function, the increase of rumen mucous membrane permeability and the occurrence of bacterial translocation by heat stress may be due to the declined expression of tight junction protein occludin mRNA.%[目的]研究热应激对奶山羊瘤胃上皮细胞屏障通透性的影响，为动物在炎热环境中能够维持正常生理机能以及探索促进动物抗热应激的方法提供理论基础和试验依据。[方法]选用泌乳中后期奶山羊，采用逐渐加热的方式建立奶山羊热应激模型，研究热应激对奶山羊血浆中 D-乳酸、DAO、内毒素及炎性细胞因子等异常代谢产物的浓度，瘤胃上皮细胞间紧密连接的变化及紧密连接蛋白Occludin表达的影响。[结果]①热应激显著提高了血浆中D-乳酸和DAO浓度；②热应激显著提高了血浆中内毒素及炎性细胞因子TNF-α、IL-1α、IL-6、IL-1β、干扰素-γ的浓度；③热应激破坏了瘤胃上皮间紧密连接的结构，并显著降低了紧密连接蛋白 Occludin 蛋白表达和mRNA表达。[结论]热应激可导致奶山羊瘤胃黏膜屏障功能受损、通透性增加、菌群移位，其机制可能与瘤胃上皮细胞紧密连接蛋白Occludin表达下降有关。
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