Dexmedetomidine alleviates intestinal barrier dysfunction and inflammatory response in mice via suppressing TLR4/MyD88/NF-κB signaling in an experimental model of ulcerative colitis

Introduction. Ulcerative colitis (UC) is a nonspecific intestinal inflammatory disease. Dexmedetomidine (DEX) is a selective alpha 2-adrenergic receptor agonist commonly used for analgesia and sedation in intensive care units. Herein, the role and mechanism of DEX in dextran sulfate sodium (DSS)-induced colitis was explored. Materials and methods. A murine model of DSS-induced colitis was established by adding 3.5% (w/v) DSS in drinking water to C57BL/6J female mice. The severity of colitis was measured by the disease activity index (DAI) score, colon length and body weight of mice. The serum concentration and mRNA levels of inflammatory cytokines in colon tissues were assessed by ELISA and RT-qPCR, respectively. Protein levels of apoptotic markers, tight junction proteins and genes involved in the TLR4/MyD88/NF-κB signaling were quantified utilizing Western blotting. The pathological changes of colon tissues were evaluated by hematoxylin-eosin (HE) staining and histological score. Intestinal permeability in vivo was assessed by fluorescein isothiocyanate (FITC)–dextran (FITC-D) administration. TUNEL assay was used to determine cell apoptosis in the intestinal epithelium. Results. DSS administration resulted in weight loss, shortening of the colon, increased DAI score, histological abnormalities, and increased serum FITC-D levels in mice, all of which were reversed by DEX injection. Moreover, DEX attenuated DSS-triggered inflammatory response, intestinal barrier injury and intestinal epithelial cell apoptosis. Mechanically, DEX inactivated the TLR4/MyD88/NF-κB signaling in the colon tissues. Conclusions. DEX exerts beneficial effects against the intestinal barrier dysfunction, inflammatory response, and apoptosis of intestinal epithelial cells via inactivation of the TLR4/MyD88/NF-κB signaling in mice with DSS-induced colitis