| Objective:To establish non-alcoholic fatty liver disease (NAFLD) model by high fat diet inC57BL/6J mice, to observe the effects of Zinc-alpha2-glycoprotein (ZAG) onNAFLD and explore its mechanism.Methods:Male C57BL/6J mice(n=40) were used for experiments at8weeks of age after1week of acclimation period, then randomly divided into standard-fat diet (SFD) group(n=10) and high fat diet (HFD) group (n=30). Body weight was measured weekly.After20weeks,10mice were randomly selected from HFD group giving1ml titer2×1011v.g of adeno-associated virus (rAAV2-ZAG-GFP) by tail vein injection (HFD+ZAG), the rest20mice in group HFD were divided randomly into two group with10in each other, one group was given the same titer rAAV2-GFP1ml by tail veininjection (HFD+vector), all of them were continued to be fed on high fat diet for4weeks. Serum TG, TC, LDL, HDL level were assessed by biochemical automaticanalyzer, FFA level was measured by ELISA, liver, subcutaneous and visceral adiposewere stored in10%formalin, after paraffin embedding, sections were stained withhematoxylin and eosin. The content of hepatic TG, TC, FC, CE were detected bybiochemical automatic analyzer. The mRNA and protein expression of ZAG in liverwere detected by qRT-PCR and Western Blot. The expression of metabolic nuclearreceptors and related genes, such as sterol regulatory element binding protein-1c(SREBP1c), peroxisome proliferator-activated receptor (PPARα), liver X receptor(LXR), farnesoid X receptor (FXR), fatty acid translocation enzyme (CD36), fattyacid transfer protein (FATP4), fatty acid binding protein (FABP), fatty acid synthase(FAS), stearoyl coenzyme A desaturase-1(SCD1), carnitine palmitoyl transferase-1(CPT1) and uncoupling protein-1(UCP1) were detected by Western Blot.Results:Weight, the size of adipocytes and serum TC, TG, LDL level were markly increased in HFD and HFD+vector mice compared with SFD group (P<0.05). SerumFFA, hepatic TG, TC, FC, CE level in HFD and HFD+vector group were significantlyhigher than SFD group (P<0.01), CE/TC%level in HFD and HFD+vector group wasincreased by57.5%and63%. In HFD and HFD+vector group, HFD-inducedremarkably decrease in liver ZAG at mRNA (P<0.01) but no clear difference atprotein levels compared with SFD group (P>0.05). No significant difference on theprotein expression of PPARα, CPT1and SCD1between SFD group and HFD,HFD+vector group (P>0.05). The expression level of FXR protein was lower(P<0.05), the expression level of UCP1was significantly lower than SFD group(P<0.01), the expression level of SREBP1c, LXR and FABP were higher (P<0.05),the expression level of CD36, FATP4and FAS were significantly higher than SFDgroup (P<0.01).Compared with HFD and HFD+vector group, the weight of mice and liver weresignificantly lower in HFD+ZAG group (P<0.05), the size of adipocytes wassignificantly lower in HFD+ZAG group, serum TG, LDL, FFA and hepatic TG, TC,FC, CE level were significantly higher in HFD+ZAG group (P<0.01), CE/TC%levelwere decreased by53.2%. Meanwhile, the mRAN and protein expression of ZAG inliver were up-regulated remarkably compared with HFD and HFD+vector group(P<0.01). The expression level of FXR, CPT1protein were significantly higher(P<0.05), the expression level of PPARa, UCP1protein were obviously higher inHFD+ZAG group (P<0.01), the expression level of LXR, FABP, SCD1protein weresignificantly lower (P<0.05), the expression level of SREBP1c, CD36, FATP4, FASprotein were obviously lower (P<0.01).Conclusions:1. ZAG reduces weight of mice, the size of adipocytes and the level of serum TG, LDL, with lipid-lowering effect of weight loss;2. ZAG reduces liver weight, the number of lipid droplets in the liver andthe level of hepatic TG, TC, FC, CE, CE/TC%, which improving NAFLD.3. ZAG inhibites the expression of hepatic TG synthesis and intake associatedfactors SREBP1c, LXR, CD36, FATP4, FABP, SCD1, FAS protein, promotes theexpression level of fatty acid β-oxidation factors PPARa, FXR, CPT1, UCP1protein,and thus improves liver lipid deposition and NAFLD. |
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