UCLA

The etiology of nonalcoholic fatty liver disease is complex and influenced by factors such as obesity, insulin resistance, hyperlipidemia, and sex. We now report a study on sex difference in hepatic steatosis in the context of genetic variation using a population of inbred strains of mice. While male mice generally exhibited higher concentration of hepatic TG levels on a high-fat high-sucrose diet, sex differences showed extensive interaction with genetic variation. Differences in percentage body fat were the best predictor of hepatic steatosis among the strains and explained about 30% of the variation in both sexes. The difference in percent gonadal fat and HDL explained 9.6% and 6.7% of the difference in hepatic TGs between the sexes, respectively. Genome-wide association mapping of hepatic TG revealed some striking differences in genetic control of hepatic steatosis between females and males. Gonadectomy increased the hepatic TG to body fat percentage ratio among male, but not female, mice. Our data suggest that the difference between the sexes in hepatic TG can be partly explained by differences in body fat distribution, plasma HDL, and genetic regulation. Future studies are required to understand the molecular interactions between sex, genetics, and the environment.