Abstract: Objective:To observe the regulatory effect of linalotide combined with prucalopride on intestinal flora and brain-gut axis function in mice with irritable bowel syndrome with constipation (IBS-C).Methods:50 C57BL/6 wild-type mice were randomly divided into normal group, model group, linalotide group, prucalopride group and combined administration group according to body weight, with 10 mice in each group.The normal group was fed normally, and the other groups established IBS-C model by ice water gavage.After the model was successfully established, the linalotide group and the prucalopride group were treated by gavage respectively.The combined administration group was treated by gavage of linalotide and prucalopride once a day for 14 days.The changes of fecal particles and fecal water content of mice in each group and the gastric residual rate and intestinal propulsion rate of mice were determined by gastric perfusion with ink.HE staining was used to observe the morphological change of colonic mucosa of mice.The number of Bifidobacterium, Lactobacillus and Escherichia coli in mouse feces were compared by bacterial culture identification method.Levels of 5-hydroxytryptamine (5-HT), vasoactive intestinal peptide(VIP)and substance P(SP) in serum were measured by enzyme-linked immunosorbent assay (ELISA).Western blotting and real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) were used to detect the relative expression levels of 5-hydroxytryptamine receptor 4 (5-HT₄R), 5-HT transporter (SERT) protein and mRNA in colon tissue.Results:Compared with the model group, the number of fecal particles and the fecal water content in each treatment group significantly increased (P< 0.05).The gastric residual rate was significantly reduced (P< 0.05), and the intestinal propulsion rate increased significantly (P< 0.05).The number of Bifidobacterium and Lactobacillus in stool increased (P< 0.05), and the number of Escherichia coli decreased (P< 0.05).The serum SP level increased significantly (P< 0.05), and the levels of 5-HT and VIP decreased (P< 0.05).The expression levels of SERT protein, mRNA and 5-HT₄R protein and mRNA in colon tissues significantly increased(P< 0.05).Among them, the improvement effect of each index in the combined administration group was more obvious than that of linalotide and prucalopride alone (P< 0.05).Conclusion:Linalotide combined with prucalopride can effectively alleviate the symptoms in IBS-C mice, which may be related to the regulation of intestinal flora in mice and the improvement of brain-gut axis disorder.