The FLS mouse: A new inbred strain with spontaneous fatty liver

Background and Purpose: A new strain of mouse, named FLS (fatty liver Shion ogi), which develops spontaneous fatty liver without obesity, was establish ed by inbreeding. Morphologic, physiologic, and genetic characterization of the strain was done. Methods: Characteristics of male FLS mice were compared with those of the s ister strain, dd Shionogi (DS), which does not develop spontaneous fatty li ver. A genetic cross experiment was performed by mating FLS with C3H/He/Shi mice. Results: The hepatocytes of neonatal FLS mice contained fine lipid droplets throughout the lobules, and large lipid droplets appeared as mice aged. Li ver triglyceride concentrations of FLS mice were fivefold higher than those of DS mice, but serum lipid concentrations and the lipoprotein profile did not indicate abnormalities, Higher plasma aspartate transaminase and alani ne transaminase activities in FLS, compared with DS mice, suggested hepatoc ellular lesions. The genetic cross experiment suggested that the fatty live r formation is a complex polygenic trait. Conclusion: The FLS mice develop a progressive hepatic steatosis without ob esity and diabetes. The FLS mouse might be a good model for investigating h epatic disorders accompanied by fatty liver unrelated to alcoholism or obes ity.