Utility of ultrasonography in a mouse model of non-alcoholic steatohepatitis induced by a choline-deficient, high-fat diet and dextran sulfate sodium.

ABSTRACT

Background: Nonalcoholic steatohepatitis (NASH) is a chronic progressive liver disease that can progress to cirrhosis and hepatocellular carcinoma. The prevalence of NASH is increasing year by year. However, the etiology and progression of NASH, along with the processes leading to carcinogenesis, remain poorly understood. A range of animal models are used in research, but investigators have been unable to establish a model that results in tumorigenesis from a stable disease state. The present study aimed to create a stable, low-mortality model of NASH using abdominal ultrasonography (US) to assess NASH stage and diagnose liver tumors. Methods: Thirty-four 19-week-old male C57BL/6J mice were fed a choline-deficient, high-fat (CDHF) diet. Twenty animals were given seven courses of 0.8 % dextran sulfate sodium (DSS) for 7 days followed by 10 days of MilliQ water (CDHF+DSS group). The remaining 14 animals drank only MilliQ water (CDHF group). All animals were weighed weekly and US was performed on Days 35 and 120. After necropsy, samples were taken for biochemical analysis and histopathological evaluation. Results: The CDHF+DSS group had significantly lower body weight on Days 35 and 120, and significantly higher liver/body weight (%) on Day 35 compared to the CDHF group. US on Days 35 and 120 revealed significantly shorter long intestine and higher colonic histological score in the CDHF+DSS group compared to the CDHF group. IL-1ß and IL-6 levels in the large intestinal tissue were significantly higher in the CDHF+DSS group. Conclusions: A stable, low-mortality model of NASH was created with a CDHF diet and intermittent 0.8 % DSS. Abdominal US can assess the degree of fatty degeneration and evaluate liver tumorigenesis without necropsy. This assessment procedure will reduce the number of mice killed unnecessarily during experiments, thereby contributing to animal welfare.