| Objective:To explore the protective effects of tea polyphenols on the treatment of alcoholic liver disease and it's possible mechanism by observing it's regulatory role on the expression of PPARαand NF-κB in the animal and cell models of alcoholic liver disease.Methods:1. In vivo experiments30 Wistar rats were randomly divided into the following 3 groups: control group treated with common feed; model group treated with common feed and alcohol; TP Group was treated with tea polyphenols in addition to common feed and alcohol, all rats were sacrificed at the end of the seventh week. Then, serum ALT,AST,and MDA were detected by biochemical assays, basic pathological changes of the rats were observed using routine HE staining and fatty degeneration of liver tissues was evaluated by SudanⅣstaining under light microscope (LM). The expression of PPARαand NF-κB were determined by RT-PCR and Electrophoretic Mobility Shift Assay (EMSA), respectively.2. In vitro experimentsImmortalized fetal liver cell line L02 was cultured and divided into 5 groups: control group, model group (treated with alcohol), TP A group (cells were treated with TP for 3 days, and then treated with alcohol for 3 days), TP B group (cells were treated with TP and alcohol at the same time for 3 days), TP C group (cells were treated with alcohol for 3 days, and then treated with TP for 3 days). The above-mentioned interfering factors were added after the cells were adherent to the culture dish. The cells were subcultured every 7 days. After four weeks, changes of lipid droplets in L02 cell were observed using oil red O staining, ALT,AST,GGT,TG in the cell supernatant of each group were detected, and Reactive oxygen species(ROS) in cells was quantified by optical density measurement and fluorescence microscope. The expression of PPARα, NF-κB and IκB in cells were determined by RT-PCR, and the activity of NF-κB in cells was checked with EMSA.Results:1. ALD animal models were successfully established. serum ALT,AST and the degradation products of lipid peroxide MDA in model group rats were statistically higher than that in the control group; whereas serum ALT,AST and MDA in TP group were statistically lower than that in the model group.2.Steatosis was evident in model rats, with the lipid area more than 30% of the liver, inflammatory, fibrosis were not found in model group; the degree of liver steatosis in the TP group was significantly lower that in the model group.3. Compared with control group, the expression of PPARαmRNA decreased, on the contrary, the activity of NF-κB increased in model group; compared with model group, the expression of PPARαmRNA increased and the activity of NF-κB was significantly lower in TP group in rats.4. L02 ALD cell models were successfully established; MTT showed that certain concentration of TP can ease the damage caused by ALD.5. The degree of steatosis and active fluoresce in TP A, B, C group was lower than that of model group, whereas the levels of ALT, AST, GGT, TG, ROS were the similar.6. The expression levels of PPARαmRNA, IκB mRNA in L02 cells decreased in the model group, whereas PPARαand IκB increased in control group; the level of PPARα, IκB mRNA expression in the TP A, B, C group were significantly higher than that of alcohol-treated model group; the expression of NF-κB was consistent with activity of NF-κB, TP A, B, C group were significantly lower than that of model group.Conclusion:1. Oxidative stress and lipid peroxidation was involved in the occurrence of alcoholic liver disease; tea polyphenols may ease the liver damage in vitro and in vivo via the role of anti-oxidation.2. The molecular mechanism of tea polyphenols'protective effects on ALD involved upregulating PPARαexpression level and inhibiting the activation of NF-κB.3. TP can interfere with the development of ALD and can alleviate the liver damage in ALD modes at different time points, thus protecting liver cells.
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