A long-term of high concentration feeding in ruminants can bring huge economic profits, but it also impose ruminants into great threat of suffering subacute ruminal acidosis (SARA). SARA is a kind of disease which attenuate the health, feed intake and production of ruminants, and when ruminants suffer SARA, the concentration of lipopolysaccharide (LPS) increase largely. Glycyrrhizin is reported to have anti-inflammation effects, and the study was conducted to investigate effects of glycyrrhizin on LPS-induced goat ruminal epithelial cells (GRECs) to provide evidence for using glycyrrhizin as a treatment for SARA. Effects of LPS, and glycyrrhizin on cell viability of GRECs were investigated, respectively. Then GRECs were stimulated with LPS (50 mg/L) for 2 h, and glycyrrhizin were added at the concentration of 0, 50, 75, 100 and 125 mg/L for 24 h to investigate the expression of inflammatory cytokines (by Elisa kits), the mRNA expression of NF-κB and inflammatory cytokines (by qRT-PCR), the distribution of Zo-1 and Occludin (by immunofluorescence staining), the expression of Occludin (by Western blot analysis), and the morphology of GRECs. The results showed that: (1) Glycyrrhizin at the concentration of 50, 75, 100, and 125 mg/L had no cytotoxic effects on GRECs, and LPS at the concentration of 50 mg/L significantly decreased the cell viability of GRECs. (2) Glycyrrhizin attenuated the expression and relative mRNA expression of TNF-α, IL-1β, IL-6, IL-8 and IL-12 by a dose-dependent manner, and significantly attenuated the relative mRNA expression of NF-κB. (3) Immunofluorescence staining and Western blot analysis showed that the quantity of Zo-1 and Occludin, and the expression of Occludin all increased with the treatment of glycyrrhizin. (4) Glycyrrhizin attenuated LPS-induced autophagy and protected the structural integrity of GRECs. In conclusion, glycyrrhizin significantly inhibited the inflammatory response in LPS-stimulated GRECs, and it may be used as a potential agent for the treatment of SARA.

中文翻译：

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甘草甜素抑制LPS诱导的山羊瘤胃上皮细胞的炎症反应

长期以高浓度喂养反刍动物可带来巨大的经济利益，但也使反刍动物面临遭受亚急性瘤胃酸中毒（SARA）的巨大威胁。SARA是一种会削弱反刍动物的健康，采食量和反刍动物产生的疾病，当反刍动物遭受SARA时，脂多糖（LPS）的浓度会大大增加。据报道，甘草甜素具有抗炎作用，并进行了研究以研究甘草甜素对LPS诱导的山羊瘤胃上皮细胞（GREC）的作用，从而提供了使用甘草甜素治疗SARA的证据。分别研究了脂多糖和甘草甜素对GRECs细胞活力的影响。然后用LPS（50 mg / L）刺激GRECs 2 h，并以0、50、75，在100和125 mg / L的条件下持续24 h，以研究炎症细胞因子的表达（通过Elisa试剂盒），NF-κB和炎症细胞因子的mRNA表达（通过qRT-PCR），Zo-1和Occludin的分布（通过免疫荧光法）染色），Occludin的表达（通过蛋白质印迹分析）和GREC的形态。结果表明：（1）50、75、100和125 mg / L的甘草甜素对GRECs无细胞毒性作用，而50 mg / L的LPS则显着降低GRECs的细胞活力。（2）甘草甜素以剂量依赖性的方式减弱了TNF-α，IL-1β，IL-6，IL-8和IL-12的表达和相对mRNA表达，并显着减弱了NF-κB的相对mRNA表达。（3）免疫荧光染色和Western blot分析表明，Zo-1和Occludin的含量，甘草甜素处理后Occludin的表达均增加。（4）甘草甜素减弱了LPS诱导的自噬并保护了GRECs的结构完整性。总之，甘草甜素显着抑制了LPS刺激的GRECs的炎症反应，可作为治疗SARA的潜在药物。