Effects of Six Weeks of Hypoxia Exposure on Hepatic Fatty Acid Metabolism in ApoE Knockout Mice Fed a High-Fat Diet.

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease with a characteristic of abnormal lipid metabolism. In the present study, we employed apolipoprotein E knockout (ApoE KO) mice to investigate the effects of hypoxia exposure on hepatic fatty acid metabolism and to test whether a high-fat diet (HFD) would suppress the beneficial effect caused by hypoxia treatment. ApoE KO mice were fed a HFD for 12 weeks, and then were forwarded into a six-week experiment with four groups: HFD + normoxia, normal diet (ND) + normoxia, HFD + hypoxia exposure (HE), and ND + HE. The C57BL/6J wild type (WT) mice were fed a ND for 18 weeks as the baseline control. The hypoxia exposure was performed in daytime with normobaric hypoxia (11.2% oxygen, 1 h per time, three times per week). Body weight, food and energy intake, plasma lipid profiles, hepatic lipid contents, plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and molecular/biochemical makers and regulators of the fatty acid synthesis and oxidation in the liver were measured at the end of interventions. Six weeks of hypoxia exposure decreased plasma triglycerides (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) contents but did not change hepatic TG and non-esterified fatty acid (NEFA) levels in ApoE KO mice fed a HFD or ND. Furthermore, hypoxia exposure decreased the mRNA expression of