Study On Protective Effect Of Corn Peptide On Fatty Liver Disease In Rats Induced By High Fat Diet

As the world’s most common liver disease,fatty liver disease(FLD)poses a great challenge to human health and life,however there are no effective treatment drugs or methods for FLD at home and abroad.nowadays,bioactive peptides have attracted much attention in the fields of food and medicine because of their wide sources,varieties and good nutritional regulation.Now the hepatoprotective effect of corn peptides has been confirmed by more and more studies,which provides the possibility to improve the occurrence and development of FLD.In this study,a FLD rat model was established by feeding rats with high-fat diet,at the same time,different doses of corn peptide were given and observe the effect,in order to explore the protective effect of corn peptide on FLD.Part one Establishment of FLD rat model and preliminary study on the intervention effect of corn peptideObjective: To determine the time of establishing rat FLD model,and preliminarily explore the dose effect of corn peptide on the protective effect of FLD.Methods: Fifteen male SD rats were randomly divided into control group,model group,low-,medium-,high-dose corn peptide group,the experiment started after 1 week of adaptive feeding.The control group was fed with ordinary feed and given intragastric administration of purified water at the same time,and the remaining 4 groups were fed with high-fat feed,the model group was given intragastric administration of purified water while the low-,medium-,high-dose corn peptide groups were given intragastric administration of 400,600,800 mg/kg·d of corn peptide respectively,for 10 weeks.The body weight and general condition of rats were recorded every week,after 10 weeks,the serum TG,AST,ALT levels and liver index of the 5groups were compared,the liver morphology and pathological changes were observed.The statistical analysis was performed using SPSS 21.0 statistical software.A p value less than 0.05 was considered statistically significant.Results: The serum TG,AST,ALT level and liver index of rats in model group were significantly higher than those in control group(P<0.05);The serum TG,AST,ALT level and liver index in the low-,medium-,high-dose corn peptide groups were higher than those in the control group and lower than those in the model group,but there was significant difference in all the indexes in the high-dose group compared with the model group only;With the dose of corn peptide increased,the serum TG,AST,ALT level and liver index of rats showed a decreasing trend,but not all differences were statistically significant;The liver morphology and tissue sections showed that there was obvious steatosis in the liver of the model group,but no steatosis occurred in the low-,medium-and high-dose groups of corn peptide,and the degree of liver fat infiltration decreased gradually with the increase of corn peptide gavage dose.Conclusions: A rat FLD model was successfully established with a period of 10 weeks;Corn peptide shows a preventive effect on the occurrence of FLD and shows a certain dose gradient trend,which could be verified by the next step.Part two Study on the protective effect and mechanism of corn peptide on FLDObjective: To explore the dose-effect and mechanism of the protective effect of corn peptide on FLD.Methods: seventy male SD rats were randomly divided into control group,model group,CP group,Puerarin positive control group,low-,medium-,high-dose corn peptide group,the experiment started after 1 week of adaptive feeding.The control group and CP group were fed with ordinary feed and others were fed with high-fat feed,while the control group was given intragastric administration of purified water,the CP group and the low-,medium-,high-dose corn peptide group were given intragastric administration of 600,400,600,800 mg/kg·d of corn peptide respectively,and the puerarin positive control group was given intragastric administration of 300 mg/kg·d of puerarin,for 10 weeks.The body weight and general condition of rats were recorded every week,after 10 weeks,the indexes of 7 groups were compared.The statistical analysis was performed using SPSS 21.0 statistical software.A p value less than 0.05 was considered statistically significant.Results: Compared with the control group,the rats in the model group weight decreased and the liver weight and liver index increased(P<0.05);FBG,AUC and HOMA-IR increased(P<0.05);Serum FINS,TG,TC,FFA,LDL-C,LEP,IL-6,TNF-α levels and liver TG,TC,FFA levels increased(P<0.05)while serum HDL-C level decreased(P<0.05);Serum AST and ALT activities increased(P<0.05);Serum and liver SOD,GSH-Px activities decreased and MDA content increased(P<0.05);The liver became larger and the color changed from dark red to khaki,Liver tissue sections showed excessive lipid accumulation and severe steatosis.Except for the serum FINS activity of CP group was lower than control group(P<0.05),there were no statistical difference in other indicators compared with the control group.Compared with the model group,the weight of the rats in the three doses of corn peptide groups increased(P<0.05)while the liver weight and liver index decreased(except for the low-dose group,P<0.05);The FBG,AUC,HOMA-IR decreased(P<0.05)and were negatively correlated with the intervention dose of corn peptide;The serum FINS,TG,TC,FFA,LDL-C,LEP,IL-6,INF-α level and liver TG,TC,FFA level decreased(P<0.05)and were negatively correlated with corn peptide intervention dose,serum HDL-C level increased(P<0.05)and was positively correlated with corn peptide intervention dose;The serum AST,ALT activity decreased(P<0.05)and were negatively correlated with corn peptide intervention dose;serum and liver SOD,GSH-Px activity increased and positively correlated with corn peptide intervention dose,MDA content decreased(P<0.05)and negatively correlated with corn peptide intervention dose;The size of the liver became smaller,the liver color gradually changed from light yellow to light red with the increase of corn peptide intervention dose,liver tissue sections showed that lipid accumulation in hepatocytes decreased gradually with the increase of corn peptide intervention dose and no steatosis occurred.Conclusions: Corn peptide plays an important role in preventing the occurrence of FLD in rats,and its preventive effect is proportional to the intervention dose of corn peptide,and high-dose corn peptide is better than puerarin in preventing the occurrence of FLD;The mechanism of action of corn peptide is to enhance the glucose tolerance,alleviate insulin resistance,decrease blood lipid content and liver lipid accumulation,reduce liver function damage,weaken inflammation,improve oxidative stress,and prevent liver cell steatosis of rats.