2.7. Preparation of CCl4-Induced Liver Injury Mice

The mouse model of CCl₄-induced liver injury was produced by subcutaneous injection of 5 μL 20% CCl₄ (olive oil as solvent) once every two days for 3 weeks [14]. The control was given olive oil only. After CCl₄ treatment for 3 weeks, the CCl₄-treated mice were classified into three groups randomly (n =  10 in each group). Mice in the H-bihistidine-treated group were intravenously injected with 5 mg/kg H-bihistidine once a day for 7 days. The mice in histidine group were given an equal quantity of histidine. The model mice were injected with an equal volume of saline solution. After H-bihistidine treatment, all mice were euthanized and blood was obtained to prepare serum. Then, serum levels of ALT and AST were evaluated by using the automatic biochemistry analyzer. The liver tissue sections were stained utilizing hematoxylin–eosin (HE) staining. In addition, the levels of ROS, MDA, GSH, SOD, and ATP in the tissue homogenate were calculated utilizing the commercial kits.