RESUMO
OBJECTIVE To explore the effect and mechanisms of baicalein on 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced experimental colitis in mice.METHODS BALB/c mice were randomly placed into three groups (n=10):normal control group,TNBS group,and TNBS+baicalein (20 mg· kg-1,once per day) group.Mouse colitis was induced by intrarectal injection of TNBS.Baicalein was administered by oral gavage two days prior to TNBS treatment and until the end of the study (a total of 9 d).The colon length was measured before HE staining was performed for histological damage assessment.The remaining colon pieces were collected to measure the content of tumor necrosis factor-α(TNF-α).Lipopolysaccharide (LPS)-stimulated RAW264.7 mouse macrophage was used as a cell model to determine the content of nitric oxide (NO) in cell culture medium,the mRNA levels of TNF-α,interleukin-6(IL-6),IL-1β,inducible nitric oxide synthase(iNOS),cyclooxygenase 2(COX-2) and monocyte chemoattractant protein-1 (MCP-1),and the protein expression of phosphatidylinositol 3-kinase/protein kinase B/nuclear factor-κB (PI3K/AKT/NF-κB) pathway.RESULTS Baicalein significantly attenuated TNBS-induced colon shortening and histological injury (P＜0.05),which was correlated with the decline in the content of TNF-α in the colon.According to the jn vivo results,baicalein exposure down-regulated the secretion of NO and the mRNA expression of pro-inflammatory mediators (iNOS,COX-2,MCP-1,TNF-α,IL-1β and IL-6) in LPS-stimulated RAW264.7 cells (P＜0.05,P＜0.01).Additionally,the phosphorylation/activation of LPS-stimulated PI3K/AKT/NF-κB pathway was inhibited by baicalein treatment.CONCLUSION The beneficial effect of baicalein in TNBS-induced experimental colitis may be due to PI3K/AKT/NF-κB signaling inhibition.