Abstract
Objectives
Nonalcoholic fatty liver disease (NAFLD) incidence and prevalence have been reported to be higher in men than women, however, the effects of sexual dimorphism on NAFLD risk and progression have not been adequately examined. Our lab has previously shown that a liquid high-refined carbohydrate diet (HRCD) induced more severe hepatic steatosis compared to an isocaloric high fat diet in male mice. Also, HRCD-induced reduction in sirtuin 1 (SIRT1), an NAD-dependent deacetylase protein, has previously been implicated in NAFLD pathogenesis. Therefore, we investigated whether there were sexually dimorphic responses to a liquid high-refined carbohydrate diet (HRCD) in male and female, wildtype and SIRT1-deficient mice.
Methods
Male and female 10–12-week-old wildtype (SIRT1 +/+: n = 12; M = 6, F = 6) and mice carrying a heterozygous H355Y SIRT1 point mutation (SIRT1 +/y: n = 14; M = 7, F = 7) were both fed a HRCD (Lieber-DeCarli liquid diet supplemented with maltose dextrin; 47% energy from refined carbohydrate, Dyets, #710,260) for 5 weeks and 9 weeks. Hepatic gene expression was examined using qRT-PCR. Plasma ALT (alanine transaminase) and hepatic MDA (malondialdehyde) levels were determined using colorimetric assay kits. Hepatic steatosis scoring was conducted by analyzing Hematoxylin and Eosin (H&E) stains.
Results
9 weeks of HRCD induced significantly less hepatic steatosis in female mice irrespective of genotype compared to male mice as determined by grading of H&E stains (P < 0.05). Furthermore, liver expression of several fatty acid oxidation genes (CPT1, ACOX1) was significantly higher in females (P < 0.05), which potentially suggests increased fatty acid oxidation. Additionally, female mice had significantly increased antioxidant gene expression (GPX4, SOD1, SOD2, Catalase) and significantly lower hepatic MDA (P < 0.05), which indicate an increased capacity to mitigate oxidative stress. Lastly, plasma ALT levels were significantly lower in females compared to males after 9 weeks of HRCD (P < 0.05).
Conclusions
Collectively, these data indicate that female mice are moderately protected against HRCD-induced NAFLD compared to male mice, potentially through increased hepatic fatty acid oxidation and superior mitigation of oxidative stress due to increased antioxidant system gene expression in the liver.
Funding Sources
HNRCA, USDA/ARS Grants.
PPARα-Deficient ob/ob Obese Mice Become More Obese and Manifest Severe Hepatic Steatosis Due to Decreased Fatty Acid Oxidation
