The Protective Effects Of Lycium Barbarum Polysaccharides Against CCl₄-Induced Liver Fibrosis In Rats And Their Mechanism

Hepatic fibrosis is a common pathological basis of various chronic liver diseases.Multiple cytokines,growth factors,matrix and its degrading enzymes involve in the occurrence and development of hepatic fibrosis.'The incidence of hepatic fibrosis in our country is increasing,seriously threatening the pets and humans' health.Studies have confirmed that hepatic fibrosis is a reversible pathological process,if appropriate and effective treatments are carried out in the early onset,we can not only prevent the progression of hepatic fibrosis but also even reverse it.Therefore,searching effective drugs to prevent and treathepatic fibrosis is of great significance.Lycium barbarum polysaccharides,an important active ingredient of our traditional Chinese medicine,has many pharmacological effects including effectively improving the antioxidant activity,removing excessive free radicals,regulating immunity and so on.Researches have shown that LBP can effectively alleviate hepatotoxicity in rat,however,the specific mechanism is rarely reported.Our study was conducted based on the researches before.We used CCl4 to establish the liver fibrosis model in rats and analyzed the protective effects of LBP on CCl4-induced liver fibrosis,and further explored the specific protective mechanism.Main contents were as follows:Experiment I The protective effects of LBP on CCl4-induced liver fibrosis in rats 50 Wistar rats were randomly divided into five groups(n= 10):Control group,CCl4 model group,low dose LBP group,middle dose LBP group,high dose LBP group.Except rats in control group,all rats received 40 v/v%CCl4(dissolved in olive oil)2 mL/kg body weight twice a week for 8 weeks through gavage to induce hepatic fibrosis.Rats in LBP groups received 400 mg/kg,800 mg/kg and 1600 mg/kg LBP on the basis of model group,once a day for 8 weeks,respectively.At the end of the experiment,we observed the effects of LBP on the growth performance of rats,ALT,AST and ALP activities in serum,histopathological changes and expressions of TGF-?1,?-SMA and Col-1 in rat livers.Results indicated that LBP could significantly ameliorate rats' mental status and growth performance and markedly increase the body weight gain and decrease the liver weight and liver index in model group(P<0.05).LBP could effectively decrease CCl4-induced increased levels of ALT,AST and ALP in rats serum as well as pathological injury in liver fibrosis(P<0.05).LBP also significantly decreased the mRNA expressions of TGF-?1,?-SMA and Col-I in hepatic fibrosis rats.The middle and high doses of LBP showed better effects in ameliorating these changes.These results indicated that LBP could effectively alleviate CCl4-induced liver damage in rats.Experiment ? The mechanism of LBP on alleviating CCl4-induced liver fibrosis in ratsTo investigate the specific mechanism of LBP on alleviating CCl4-induced liver fibrosis in rats,50 Wistar rats were randomly divided into five groups(n=10)as in experiment I.We first measured the contents of SOD,GSH-Px,GSH and MDA in rat livers.Results showed that compared with the control group,CCl4 significantly decreased the activities of SOD,GSH-Px and GSH in rat livers(P<0.05),and markedly increased the contents of MDA(P<0.05).Compared with the CCl4-treated group,400 mg/kg,800 mg/kg and 1600 mg/kg LBP could significantly increase the activities of SOD,GSH-Px,GSH and markedly decrease the contents of MDA(P<0.05).These results demonstrated that LBP could significantly up-regulate the antioxidants activities and down-regulate the lipid peroxidation in liver fibrosis rats.Further,we detected the expressions of inflammatory cytokines,TNF-?,IL-1?,MCP-1 and molecules associated with the TLRs/NF-?B signal pathway,including TLR2,TLR4,MyD88 and NF-?B in rat livers.Results indicated that compared with the control group,CCl4 significantly increased the mRNA expressions of TNF-?,IL-1? and MCP-1(P<0.05)in rat livers,indicating that CCl4 promoted the inflammatory response in rats.Compared with the CCl4 model group,LBP obviously decreased CCl4-induced expressions of inflammatory cytokines.The middle and high doses of LBP exhibited better effects in alleviating these changes(P<0.05).In addition,compared with healthy rats in control group,three doses of LBP all significantly inhibited CCl4-induced mRNA expressions of TLR2,TLR4,MyD88 and NF-?B as well as protein expressions of TLR2,TLR4 and p-p65(P<0.05).These changes were consistent with the expressions of inflammatory cytokines and the results from the histopathological analysis.All these conclusions demonstrated that LBP could significantly alleviate CCl4-induced hepatic fibrosis in rats and the protective mechanism might be closely associated with the inhibition of the TLRs/NF-?B signal pathway and the expressions of inflammatory cytokines.