The Effect On CC1₄ Induced Rabbit Liver Cirrhosis By Portal Type Ⅳ Collagenase Administration

Objective:A liver cirrhosis model was established in rabbit through carbon tetrachloride subcutaneous injections and was used to investigate the anti-fibrotic effects of portal collagenase administration. The histology of cirrhotic liver was studied to evaluate the collagenolytic effects of this intervention. The expressions ofα-SMA, TIMP-1 were also explored to assess the status of hepatic stellate cells activation.Methods:New Zealand male rabbits were applied and divided into 2 groups. The animals in experimental group were injected 50% CCl4-olive oil subcutaneously with the dosage of 0.23ml/kg in the gluteal region twice a week. The control animals accepted a same volume of olive oil in same way. The liver function test were investigated at the end of 4,8,12 weeks. After 12 weeks, a liver biopsy was performed for histological evaluation. The portal delivery system (PDS) was introduced by surgery simultaneously. Thirty-three rabbits with established liver cirrhosis were divided randomly into 2 groups. The animals in group 1 (n=16) were injected 1.5ml of 0.1% typeⅣcollagenase/saline solution through PDS. The rabbits in group 2 (n=17) received the same volume of 0.9% sodium chloride as controls. The injection was conducted 5 times a week and continued for 4 weeks. Another 30 animals which were injected with olive oil only were divided into group 3 (n=15) and group 4 (n=15) and underwent the same procedure. All the animals were sacrificed after the four-week's injection, and the sera were collected for TIMP-1 detection, the livers were removed for histological examination. The expression ofα-SMA was detected by immunohistochemistry. The integral optical density and area density were calculated by an imaging analysis system. Results:The hepatic fibrosis progressed gradually as continuous injection of the toxin. The levels of ALT, AST and GGT were elevated significantly. At the end of 12th weeks, the albumin/globulin ratio was converted, and a typical cirrhotic histology was detected. In the control group the liver function and histology were normal. The mortality is 20% at the end of experiment and the achievement ratio of animal model is 83%. Portal administration of collagenase significantly attenuated liver cirrhosis. However, in the collagenase-treatment group, the integral optical density of a-SMA expression was 8.460±4.238,significantly increased compared with that of the control group of 4.090±2.506 (P<0.05). The serum level of TIMP-1 of the collagenase-treated animals (6.752±0.763ng/ml) was also significantly elevated compared with the control group (6.165±0.072 ng/ml) (P<0.05)Conclusion:The rabbit model of liver cirrhosis can be established by subcutaneous injection of carbon tetrachloride. This animal model can be used in liver cirrhosis experiment. Portal administration of collagenase can significantly attenuate liver cirrhosis whereas the a-SMA expression in liver parenchyma and serum level of TIMP-1 are increased. This may attribute to the enhanced activation of hepatic stellate cells by collagenase treatment.