Fatty liver Shionogi-ob/ob mouse: A new candidate for a non-alcoholic steatohepatitis model

Aim The fatty liver Shionogi (FLS) mouse develops hereditary fatty liver without obesity. The FLS-ob/ob mouse made by transferring the leptinob gene demonstrates several metabolic disorders and marked fat deposition in the liver. The aim was to evaluate which mouse model, the FLS or FLS-ob/ob, is more useful for non-alcoholic steatohepatitis research. Methods FLS (n=40) and FLS-ob/ob (n=40) mice were fed a standard diet for 12, 24, 36 and 48 weeks, and then killed. The degree of fat deposition, oxidative stress, fibrosis and apoptosis were analyzed in the liver. Hepatic mRNA expression of fibrogenic and pro-inflammatory cytokines was measured. Results FLS mice developed hepatic steatosis and slight fibrosis without obesity between 12 and 48 weeks of age. Conversely, FLS-ob/ob mice developed severe steatosis at 12 weeks of age, and steatohepatitis with increased oxidative stress and advanced fibrosis between 24 and 36 weeks of age. At 48 weeks of age, some FLS-ob/ob but not FLS mice, progressed to cirrhosis. Transforming growth factor-1, connective tissue growth factor and tumor necrosis factor- mRNA expression levels were greater in FLS-ob/ob than FLS mice between 24 and 48 weeks of age. The number of apoptotic cells in the liver was greater at 12 weeks of age in FLS mice and at 48 weeks of age in FLS-ob/ob mice. Conclusion FLS-ob/ob mice developed more severe steatohepatitis with fibrosis than FLS mice, and had increased oxidative stress and apoptosis. These findings indicate that the FLS-ob/ob mouse is a more useful model for steatohepatitis research.