Effect Of Ligation Of Common Bile Duct On The Protein Expression Of Insulin Signal Transduction Pathway In The Liver And Muscle Of Mice With Cirrhosis

Objective:To observe the influence of common bile duct ligation on the protein expression of insulin signal transduction pathway in the liver and muscle of mice with cirrhosis.Methods:60 healthy male c57BL/6 mice aged 6-8 weeks were randomly divided into three groups:control group(group A,n=20),sham-operation group(group B,n=20),experimental group(group C,n=20).The mice in the group A did not open the abdominal cavity and did not deal with the bile duct.The mice in the group B opened the free bile duct in the abdominal cavity but did not ligate.The mice in the group C were opened with bile duct ligation.The mice in the group A,B and C(n=10/per group)were weighed at 4~thh and 8~thh weeks respectively,and serum aspertate aminotransferase(AST),alanine amiotransferase(ALT)and albumin(ALB)were measured.Oral glucose tolerance test(OGTT),insulin release test,the area under the glucose curve(AUC_G)and the area under the insulin curve(AUC_I)were calculated to evaluate insulin sensitivity.HE staining was used to observe the pathological changes of liver tissue.Hepatic glycogen and muscle glycogen were measured by anthrone method.Western blot was used to detect the protein expression of insulin receptor(IR),phosphorylated insulin receptor(p-IR),insulin receptor substrate(IRS),protein kinase B(Akt),phosphorylated protein kinase B(p-Akt)and glucose transporter 4(GLUT-4)in the liver and muscle tissues of mice in each group.Differences among the three groups were compared by one-way analysis of variance,pairwise comparison were conducted using LSD-t test.Results:(1)At 4~thh week,compared with the group B,the body weight of the mice in the group C was significantly decreased(P<0.05),and the values of serum AST and ALT were significantly increased(P<0.05).There was no difference in ALB(P>0.05).There were no differences in OGTT and the area under the glucose curve(AUC_G)(P>0.05).The area under the insulin curve(AUC_I)in the group C was significantly increased(P<0.05).The amount of hepatic glycogen in the group C was 61.49%lower than that in the group B(P<0.05),and there was no difference in muscle glycogen(P>0.05).Liver HE staining demonstrated the small bile ducts were slightly dilated,and fibrous cords were observed around the small bile ducts,and some of them extended to the hepatic lobules.Hepatic lobule structure was disordered and local hepatocyte was necrosis.Compared with the group B,the protein expression of p-IR and p-Akt in the liver tissue of the group C decreased significantly(p-IR:0.380±0.020 vs 0.649±0.034,t=5.764;p-Akt:0.641±0.053 vs 0.924±0.103,t=4.642,both P<0.05),and there were no differences in the protein expression of IR and Akt(P>0.05).There were no differences in the protein expression of IR,p-IR,IRS,Akt and p-Akt in the muscle tissue(P>0.05).Compared with the group A,there were no differences in the protein expression of IR,p-IR,IRS,Akt,p-Akt and GLUT-4 in the liver and muscle tissues on the group B(P>0.05).(2)At 8~thh week,compared with the group B,the body weight of the mice in the group C was significantly decreased(P<0.01),and the values of serum AST and ALT were significantly increased(P<0.01).The albumin in the group C was significantly decreased(P<0.05).Compared with the group B,there were no differences in OGTT and the area under the glucose curve(AUC_G)(P>0.05).The area under the insulin curve(AUC_I)in the group C was significantly increased(P<0.05).The amount of hepatic glycogen in the group C was 74.85%lower than that in the group B(P<0.05),and there was no difference in muscle glycogen(P>0.05).Liver HE staining demonstrated the small bile duct of the mice in the group C was dilated,and the surrounding fibrosis was obvious,false lobules was developed and liver cells were necrosis seriously.Compared with the group B,the protein expression of p-IR and p-Akt in liver tissue of the group C decreased significantly(p-IR:0.267±0.030 vs 0.571±0.044,t=6.522;p-Akt:0.361±0.045 vs 0.849±0.042,t=8.001,both P<0.05),but the protein expression of IR and Akt changed slightly(P>0.05).The protein expression of p-IR,p-Akt and GLUT-4 in the muscle tissue decreased significantly(p-IR:0.055±0.006 vs 0.166±0.016,t=7.600;p-Akt:0.617±0.035 vs 0.828±0.017,t=6.005;GLUT-4:0.125±0.015 vs 0.262±0.013,t=11.120,both P<0.05),but the protein expression of IR,IRS and Akt changed slightly(P>0.05).Compared with the group A,there were no differences in the protein expression of IR,p-IR,IRS,Akt,p-Akt and GLUT-4 in the liver and muscle tissues on the group B(P>0.05).Conclusion:We built mice mode of liver cirrhosis successfully by bile duct ligation.At 4~thh weeks,the storage of hepatic glycogen was decreased and the protein expression of insulin signal transduction pathway in liver was down-regulated in experimental group.At 8~thh weeks,the storage of hepatic glycogen was further decreased.The protein expression of insulin signal transduction pathway in liver was down-regulated further,and the protein expressions of insulin signal transduction pathway in muscle were down-regulated.