The mechanism of modified Xiangsha Liujunzi Decoction in regulating apoA-Ⅰ and improving endoplasmic reticulum stress in hyperlipidemic mice
Objective To explore the mechanism of modified Xiangsha Liujunzi Decoction in regulating apolipoproteinA-Ⅰ (apoA-Ⅰ),improving endoplasmic reticulum stress,regulating glucose and lipid metabolism,and preventing and treating dyslipidemia in mice. Methods Wild-type (WT) C57BL/6J mice were randomly divided into the WT,WT+high-fat diet(HFD),and WT+HFD+Xiangsha Liujunzi Decoction(XSLJZ) groups according to the random number table method. ApoA-Ⅰ-/-mice were randomly divided into the apoA-Ⅰ-/-,apoA-Ⅰ-/-+HFD,and apoA-Ⅰ-/-+HFD+XSLJZ groups (n=10) according to the random number table method. D12492 was used for HFD feeding to establish a hyperlipidemic mouse model. Modified XSLJZ (23.66g/kg) was administered daily by gavage from the ninth week. Serum and liver tissue were collected for testing after 4 weeks. An automatic biochemical analyzer was used to detect blood lipid levels;an enzyme-linked immunosorbent assay was used to detect serum fasting blood glucose (FBG) and insulin (INS) levels,and the INS resistance index (HOMA-IR) was calculated. Hematoxylin and eosin staining was used to observe the pathological changes in the liver. Oil red O staining was used to observe the lipid deposition in the liver. TG levels in liver tissue were detected using the microplate method. Real-time PCR was used to detect apoA-Ⅰ,glucose-regulated proteins (GRP78),sterol regulatory element binding protein-1c (SREBP-1c),acetyl CoA carboxylase 1 (ACC1),and fatty acid synthase (FASN) mRNA expression levels in liver tissue. The WES fully automated protein expression analysis system was used to detect apoA-Ⅰ,GRP78,inositol-requiring enzyme 1 (IRE1),p-IRE1,c-Jun N-terminal kinase (JNK),p-JNK,insulin receptor substrate (IRS1),p-IRS1,protein kinase B (Akt),p-Akt,SREBP-1c,ACC1,and FASN protein expression levels in liver tissue. Results Compared to the WT group,the WT+HFD group showed a significant increase in serum lipids,FBG,INS levels,and the HOMA-IR index (P<0.05). The orange-red lipid droplets in liver tissue increased,fat vacuoles were apparent,and TG levels were significantly increased. ApoA-Ⅰ mRNA and protein expression levels were significantly reduced,whereas GRP78,SREBP-1c,ACC1,and FASN mRNA expression levels were increased,GRP78,SREBP-1c,ACC1,and FASN protein levels and the IRE1,JNK,IRS1,and Akt phosphorylation degree were increased (P<0.05). The serum TG,HDL-C,LDL-C,FBG,and INS levels and the HOMA-IR index in the WT+HFD group were significantly reduced after administering modified XSLJZ (P<0.05). The orange-red lipid droplets in liver tissue were significantly reduced,fat vacuolization was alleviated,and TG levels were significantly reduced,ApoA-Ⅰ mRNA and protein expression levels were significantly increased,whereas GRP78,SREBP-1c,ACC1,and FASN mRNA expression levels were reduced,GRP78,SREBP-1c,ACC1,and FASN protein expression levels and the IRE1,JNK,IRS1,and Akt phosphorylation degree were reduced (P<0.05). Compared to the WT+HFD group,the TG,LDL-C,and FBG levels and HOMA-IR index in the serum of the apoA-Ⅰ-/-+HFD group were significantly increased,whereas the HDL-C levels were significantly decreased (P<0.05). Diffuse orange-red lipid droplets in liver tissue and a significant increase in fat vacuoles were observed. Furthermore,TG levels were significantly increased,SREBP-1c,ACC1,FASN mRNA,SREBP-1c,and ACC1 protein expression levels and IRE1,JNK,IRS1,and Akt phosphorylation levels were significantly increased (P<0.05). Compared to the WT+HFD+XSLJZ group,the apoA-Ⅰ-/-+HFD+XSLJZ group showed a significant increase in serum TG,LDL-C,FBG,and INS levels,and the HOMA-IR index,whereas HDL-C levels decreased significantly (P<0.05). The deposition of orange-red lipid droplets in liver tissue improved,and TG levels significantly decreased,GRP78,SREBP-1c,ACC1,and FASN mRNA expression levels,GRP78,SREBP-1c,and ACC1 protein levels,and IRE1,JNK,IRS1,and Akt phosphorylation levels increased (P<0.05). Conclusion Modified XSLJZ improves liver glucose and lipid metabolism disorder by regulating apoA-Ⅰ to alleviate endoplasmic reticulum stress.