| Rice bran is the major resources in grain and oil in China. Strengthen in the basic research of the rice bran is very important, especially to explore its physiological functions and the molecular mechanism of some active ingredients, which will play an important role in promoting the deep development and utilization of the rice bran resources. a-Tocopherol as a member of the physiological activators in rice bran has some valuable health benefits, such as the potential prevention for various diseases. Inflammatory bowel disease (IBD) is a non-specific chronic inflammatory disease, which is closely link to genetic, intestinal infection, immune disorders, environment and the mental state. However, its etiology, pathogenesis and treatments are in continuous exploring. In this research, we have investigated the anti-inflammatory effect and its mechanism of rice bran a-tocopherol, through building inflammatory model which included Lipopolysaccharide (LPS)-stimulated murine RAW264.7macrophages in vitro and dextran sulphate sodium (DSS)-induced ulcerative colitis in C57BL/6in vivo.In the model of dextran sulphate sodium (DSS)-induced ulcerative colitis in C57BL/6, the mice were treated with1.0%DSS water for12days to establish acute colitis model. The results showed that the mice in DSS model group developed inflammation with stupor, no shiny hair, severe diarrhea and different degrees of bloody naked eye, while the weight reduced dramatically compared with the control group (Compared with the beginning of the experiments, the weight of the control group was107.29±2.79%, DSS model group was78.15±2.36%, P<0.01). The mice colon were adhere to the surrounding tissue in DSS model group, with difficult stripping, bowel wall thickening and insufflate stiff. The mucous membrane showed congestion, edema and erosion through general observation. The mice colon was became shorter and heavier in DSS group than those in control group (The control group was7.66±5.1cm, DSS model group was5.45±0.22cm, P<0.01. Colorectal weight and colorectal length ratio, the control group was0.022±0.003g/cm, DSS model group was0.041±0.005g/cm, P<0.01). The spleen was swelling with the weight of139.41±31.25mg in DSS model group, while the control group was75.49±10.48mg, P<0.01. Histopathological scores were also grading up (The control group was0.48±0.59, DSS model group was5.73±0.97, P<0.01).The slice observation showed that the inflammation of colon primarily involved mucosa and submucosa, the intestinal epithelial shedding and inflammatory cells infiltration, while the goblet cells decrease, glands and crypt destruction, and the inflammation was more serious at the end of the colon. The biochemical index suggested that the activity of MPO in the DSS model group was increased and the neutrophil infiltration was improved (The control group was0.29±0.05U/g, DSS model group was0.83±0.23U/g, P<0.01). The above adverse symptoms were improved significantly after the rice bran a-tocopherol was intervened. The weight loss, the shorter and heavier of the colon were suppressed after the rice bran a-tocopherol interfered. The weight of the spleen, disease activity index (DAI), histopathological grading and the activity of MPO were decreased. The mitigation of inflammation showed that a-tocopherol from rice bran has inhibitory effect on the mouse enteritis induced by DSS.The activity of SOD and the content of MDA in the homogenate of colon tissue were detected by biochemical methods. The results showed that the activity of SOD in DSS model group was decreased and the content of MDA was increased significantly, while the activity of SOD was improved and the content of MDA was decreased after the administration of the rice bran a-tocopherol. The results suggested that the rice bran a-tocopherol could alleviate the oxidative stress in DSS-induced mice. The expression of pro-inflammatory cytokines IL-6and TNF-a mRNA in DSS model group were higher than that in control group, while the rice bran a-tocopherol inhibited effectively the expression level of mRNA. Furthermore, the content of NO in DSS model group was higher, while it was decreased in intervention group. In addition, the rice bran a-tocopherol may reduce the release of pro-inflammatory cytokines and the activity of nitric oxide synthase (NOS), through inhibiting the oxidative stress casued by the signal transduction pathways of ROS/NFκB in DSS-iduced mice.In the model of LPS-induced murine RAW264.7macrophages in vitro, the results were confirmed by MTS method. There were no side-effects to the cells for a-tocopherol with the concentration no more than120μg/mL and1μg/mL LPS. The protective concentrations of rice bran a-tocopherol were30μg/mL,60μg/mL and120μg/mL. The secretion of IL-6and TNF-a in RAW264.7cells were detected by ELISA. The expression of pro-inflammatory cytokines were increased significantly in LPS model group, while the expression of these cytokines were decreased after the intervention of rice bran a-tocopherol, and the higher concentration of a-tocopherol, the more decrease. The LPS-stimulated macrophages had significant increase in the content of NO, while its content was decreased after the intervention of rice bran a-tocopherol, and with the increased concentration of α-tocopherol, the effect was better. In addition, the a-tocopherol derived from rice bran may have anti-inflammatory effect on LPS-stimulated RAW264.7macrophages, throught inhibiting the expression of the inflammatory mediators IL-6, TNF-a, and NO which were induced by LPS. |
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