Liraglutide protects against nonalcoholic fatty liver disease in ApoE knockout mice with high-fat diet and silenced Acrp30 by increasing AMPK

Abstract

To investigate the mechanism of liraglutide-mediated protection against nonalcoholic fatty liver disease (NAFLD) using aApoE knockout (KO) mouse with high-fat diet (HFD) and Acrp30 knockdown. Fifty-six male ApoE KO mice were divided into the following six modeling and experimental groups:regular chow fed (ApoE KO, n=10), HFD fed (HF, n=10), HFD+Adenovirus (Ad)-small hairpin (sh) Acrp30 (Ad-shAcrp30, n=10), HFD+Ad-shGreen Fluorescent Protein (GFP) (Ad-shGFP, n=6), HFD+Ad-shAcrp30+liraglutide (liraglutide, n=10), and HFD+Ad-shAcrp30+saline (saline, n=10). Weight-matched C57BL/6 mice on the regular chow diet were used as the control group (WT control, n=10).All mice were fed their assigned diet for 16 weeks.The Ad-shGFP or Ad-shAcrp30 was injected by tail vein at the end of 14 and 15 weeks.Mice in the liraglutide group received 1 mg/kg of the drug, twice daily, intraperitoneally for a total of 8 weeks (from the 9th to 16th week).Fasting blood samples were collected for testing levels of fasting plasma glucose (FPG), triglycerides (TGs), total cholesterol (TC), free fatty acid (FFA), alanine aminotransferase (ALT), Acrp30 and insulin.Liver tissue was procured for histological examination.Expression of mRNA was detected by real-time RT-PC and of protein was detected by western blot analysis. The Ad-shAcrp30 treated mice had reduced expression of Acrp30 at both the mRNA and protein levels in adipose tissues and plasma, as compared with the AdshGFP treated mice (all P < 0.01).Compared to the WT and ApoE KO groups, the HF group showed higher levels of FPG, FFA, TGs and TC (all P < 0.01); furthermore, the Ad-shAcrp30 treatment compounded these changes.The Ad-shAcrp30 treated group had markedly higher hepatic TC and TGs than the HF group (P < 0.01 and P < 0.05).Oil Red O staining showed that there was more lipid droplets in the liver tissue of the Ad-shAcrp30 treated group than in that of the HF group (P < 0.01), and hematoxylin-eosin staining confirmed these results.Liraglutide treatment prevented the increase in body weight, FPG, FFA, TGs, TC and ALT levels, as compared to the saline controls (all P < 0.01), but the plasma Acrp30 levels and the Acrp30 mRNA and protein expression in adipose tissues were elevated (all P < 0.01).Oil-Red O staining indicated that the liraglutide group had a significantly lower hepatic lipid content than the saline group, and total hepatic TG and TC were reduced in the former group (P < 0.01 and P < 0.05).The liraglutide treatment significantly attenuated the mRNA expression of ACC and FAS (both P < 0.01) but increased AMPK phosphorylation (P < 0.01). Administration of liraglutide prevented the development of HFD-and hypoadiponectinemia-induced metabolic disturbance and accumulation of hepatic lipids in this mouse model system of NAFLD.