Carbon tetrachloride-induced acute liver toxicity: selecting dosage and biomarkers for evaluating hepatoprotective drugs in ICR outbred mice

Evaluating effects of putative chemical or herbal agents against a single intraperitoneal administration of carbon tetrachloride (CCl 4 ) in rodents is a widely used model for studying hepatoprotective potency. Since the toxic effects of CCl 4 is dependent on individual species; therefore, our study aimed to demonstrate a procedure to select the optimal dosage of CCl 4 and types of liver damage-associated biomarkers for testing hepatoprotective drugs in ICR mice. To include inter-individual genetic variation, the test was conducted in outbred mice. Silymarin and rebamipide were applied as the representative tested agents. We revealed that 15-150  L/kg of CCl 4 induced liver damage including hepatocyte vacuolation and ballooning with infiltration of inflammatory cells, centrilobular necrosis, and increased serum alanine aminotransferase and aspartate aminotransferase, in a dosage-dependent manner. Nonetheless, serum levels of bilirubin were not significantly increased at 15  L/kg of CCl 4 . On the other hands, the level of alkaline phosphatase was not parallel with the increased dosage of CCl 4 . Most importantly, as observed using liver histology and serum biomarkers, rebamipide and silymarin showed hepatoprotective effects against 15  L/kg of CCl 4 merely, whereas both drugs were unable to protect liver injury against 150  L/kg of CCl 4 . In conclusion, this study demonstrated how to design an experiment to select the optimal dosage of CCl 4 for evaluating hepatoprotective effects of putative agents in a specific tested species. In addition, we revealed choices of serum biomarkers which could be associated with the severity of liver damage.