Time course of collagen peak in bile duct-ligated rats

Abstract

Background: One of the most useful experimental fibrogenesis models is the "bile duct-ligated rats". Our aim was to investigate the quantitative hepatic collagen content by two different methods during the different stages of hepatic fibrosis in bile duct-ligated rats on a weekly basis. We questioned whether the 1-wk or 4-wk bile duct-ligated model is suitable in animal fibrogenesis trials.

Methods: Of the 53 male Wistar rats, 8 (Group 0) were used as a healthy control group. Bile duct ligation (BDL) had been performed in the rest. Bile duct-ligated rates were sacrificed 7 days later in group 1 (10 rats), 14 days later in group 2 (9 rats), 21 days later in group 3(9 rats) and 28 days later in group 4 (9 rats). Eight rats underwent sham-operation (Sham). Hepatic collagen measurements as well as serum levels of liver enzymes and function tests were all analysed.

Results: The peak level of collagen was observed biochemically and histomorphometricly at the end of third week (P < 0.001 and P < 0.05). Suprisingly, collagen levels had decreased with the course of time such as at the end of fourth week (P < 0.01 and P < 0.05).

Conclusion: We have shown that fibrosis in bile duct-ligated rats is transient, i.e. reverses spontaneously after 3 weeks. This contrasts any situation in patients where hepatic fibrosis is progressive and irreversible as countless studies performed by many investigators in the same animal model.

Figure 1

Sirius red and fast green-stained liver sections showed prominent bile duct proliferation and fibrosis (× 20). Sirius red stained collagenous proteins. Fast green stained non-collagenous proteins.

Figure 2

Tricrome stained section showed portal-portal fibrosis (×40). Green areas were fibrotic and red areas were normal.

Figure 3

Hepatic collagen content increased significantly in BDL groups compared to the control and sham groups (P < 0.001). There was a difference between liver collagen content of the third group compared to groups 1, 2 and 4 (P < 0.01).

Figure 4

There was a significant increase in hepatic collagen amount in BDL groups histomorphometricaly compared to the control and sham groups (P < 0.01). Collagen peak was found at the end of the third week when compared to the groups 1, 2 and 4 (P < 0.05).

Figure 5

Serum ALT levels increased in groups 2, 3 and 4 compared to the control and the sham groups: P < 0.01 for groups 2 and 3, P < 0.01 for group 4. Serum AST levels increased in groups 1, 2, 3 and 4 compared to the control and sham group (P < 0.001).

Figure 6

Serum bilirubin levels increased in groups 1, 2, 3 and 4 compared to the control and sham groups (P < 0.001).

Figure 7

ALP leves were increased at the end of the first week. Then, it was decreased to the normal level at the end of the fourth week. The peak level of serum GGT was found at the end of the third week.