Objective:To discuss the protective effect of dexmedetomidine(DEX)on intestinal function in rats with enterogenous sepsis,and to clarify its potential mechanism based on E2F transcription factor 1(E2F1)/nuclear factor kappa B(NF-κB)signaling pathway.Methods:Sixty SD rats were selected,among which 50 rats were used to establish enterogenous sepsis models by cecal ligation and puncture(CLP),and the remaining 10 rats were used as sham operation group(only cecal separation without ligation or puncture).The 40 successfully modeled rats were randomly divided into model group,low dose of DEX group,medium,doses of DEX group,and high dose of DEX group,with 10 rats in each group.The rats in low,medium,and high dose of DEX groups were intraperitoneally injected with 20,40 and 60 μg·kg-1 DEX immediately after modeling,while the rats in sham operation group and model group were intraperitoneally injected with the same volume of saline.After 24 h of administration,the intestinal myoelectric activities of the rats in various groups were detected;the colony counts of Escherichia coli,Lactobacillus and Bifidobacterium in cecal contents of the rats in various groups were detected;the pathomorphology of small intestinal tissue of the rats was observed by HE staining;the levels of secretory immunoglobulin A(sIgA)in supernatant of small intestinal tissue homogenate and the levels of diamine oxidase(DAO)and D-lactic acid in serum of the rats in various groups were detected by kit;real-time fluorescence quantitative PCR(RT-qPCR)method was used to detect the mRNA expression levels of macrophage polarization markers in small intestinal tissues of the rats in various groups;Western blotting method was used to detect the protein expression levels of macrophage polarization markers,E2F1,phosphorylated NF-κB p65(p-NF-κB p65),and NF-κB p65 in small intestinal tissue of the rats in various groups.Results:Compared with sham operation group,the slow wave frequency and amplitude of intestinal smooth muscle of the rats in model group were decreased(P<0.05);compared with model group,the slow wave amplitude of intestinal smooth muscle of the rats in low dose of DEX groups was increased(P<0.05),the slow wave frequency and amplitude of intestinal smooth muscle of the rats in medium and high doses of DEX groups were increased(P<0.05);compared with low dose of DEX group,the slow wave frequency and amplitude of the rats in medium and high doses of DEX groups were increased(P<0.05);compared with medium dose of DEX group,the slow wave frequency and amplitude of intestinal smooth muscle of the rats in high dose of DEX group were increased(P<0.05).Compared with sham operation group,the colony count of Escherichia coli in intestinal tract of the rats in model group was increased(P<0.05),while the colony counts of Bifidobacterium and Lactobacillus were decreased(P<0.05);compared with model group,the colony count of Bifidobacterium in intestinal tract of the rats in low dose of DEX group was decreased(P<0.05),the colony count of Escherichia coli in intestinal tract of the rats in medium,and high doses of DEX groups was decreased(P<0.05),while the colony counts of Bifidobacterium and Lactobacillus were increased(P<0.05);compared with low dose of DEX group,the colony count of Escherichia coli in intestinal tract of the rats in medium and high dose of DEX groups was decreased(P<0.05),while the colony counts of Bifidobacterium and Lactobacillus were increased(P<0.05);compared with medium dose of DEX group,the colony count of Escherichia coli in intestinal tract of the rats in high dose of DEX group was decreased(P<0.05),while the colony counts of Bifidobacterium and Lactobacillus were increased(P<0.05).The HE staining results showed that the small intestinal mucosal structure in sham operation group was normal and intact;the small intestinal mucosal epithelial cells in model group were necrotic,with damaged,collapsed and disordered villi;Compared with model groups,the pathological changes of small intestinal tissues in low,medium,and high doses of DEX groups were improved.Compared with sham operation group,the level of sIgA in supernatant of small intestinal tissue homogenate of the rats in model group was decreased(P<0.05),while the protein expression levels of DAO and D-lactic acid in serum were increased(P<0.05);compared with model group,the level of DAO in serum of the rats in low dose of DEX groups was decreased(P<0.05),the level of sIgA in supernatant of small intestinal tissue homogenate of the rats in medium and high doses of DEX groups was increased(P<0.05),while the protein expression levels of DAO and D-lactic acid in serum were decreased(P<0.05);compared with low dose of DEX group,the level of sIgA in supernatant of small intestinal tissue homogenate of the rats in medium and high doses of DEX groups was increased(P<0.05),while the protein expression levels of DAO and D-lactic acid in serum were decreased(P<0.05);compared with medium dose of DEX group,the level of sIgA in supernatant of small intestinal tissue homogenate of the rats in high dose of DEX group was significantly increased(P<0.05),while the protein expression levels of DAO and D-lactic acid in serum were decreased(P<0.05).The RT-qPCR results and Western blotting results showed that compared with sham operation group,the mRNA and protein expression levels of CD86,monocyte chemoattractant protein-1(MCP-1),and CD80 in small intestinal tissue of the rats in model group were increased(P<0.05),while the mRNA and protein expression levels of CD206,interleukin-4(IL-4)and,CD163 were decreased(P<0.05);compared with model group,the expression levels of CD80 mRNA,CD86 protein and MCP-1 protein in small intestinal tissue of the rats in low dose of DEX group were decreased(P<0.05),and the expression levels of IL-4 mRNA,CD163 mRNA,CD206 protein,and CD163 protein were decreased(P<0.05),the mRNA and protein expression levels of CD86,MCP-1,and CD80 in small intestinal tissue of the rats in medium and high doses of DEX groups were decreased(P<0.05),while the mRNA and protein expression levels of CD206,IL-4 and CD163 were increased(P<0.05);compared with low dose of DEX group,the mRNA and protein expression levels of CD86,MCP-1,and CD80 in small intestinal tissue of the rats in medium and high doses of DEX groups were decreased(P<0.05),while the mRNA and protein expression levels of CD206,IL-4,and CD163 were increased(P<0.05);compared with medium dose of DEX group,the mRNA and protein expression levels of CD86,MCP-1,and CD80 in small intestinal tissue of the rats in high dose of DEX group were decreased(P<0.05),while the mRNA and protein expression levels of CD206,IL-4,and CD163 were increased(P<0.05).The Western blotting results showed that compared with sham operation group,the protein expression level of E2F1 in small intestinal tissue of the rats in model group was decreased(P<0.05),while the ratio of p-NF-κB p65/NF-κB p65 was increased(P<0.05);compared with model group,the protein expression levels of E2F1 and ratio of p-NF-κB p65/NF-κB p65 in small intestinal tissue of the rats in low,medium and high doses of DEX groups were decreased(P<0.05);compared with low dose of DEX group,the protein expression level of E2F1 in small intestinal tissue of the rats in medium and high doses of DEX groups was increased(P<0.05),while the ratio of p-NF-κB p65/NF-κB p65 was decreased(P<0.05);compared with medium dose of DEX group,the protein expression level of E2F1 in small intestinal tissue of the rats in high dose of DEX group was increased(P<0.05),while the ratio of p-NF-κB p65/NF-κB p65 was decreased(P<0.05).Conclusion:DEX can improve the small intestinal mucosal injury in the rats with enterogenous sepsis and promote the polarization of macrophages to M2 type in small intestinal tissues,and its mechanism may be related to the regulation of E2F1/NF-κB signaling pathway by DEX.