Objective To explore the mechanism of electroacupuncture in alleviating hyperlipidemia in a rat model by modulating mammalian target of rapamycin complex 1(mTORC1)-mediated lipophagy in hepatocytes.Methods A total of 30 SD rats were randomly divided into blank(n=6)and modeling groups(n=24)using the random number table method.A hyperlipidemic rat model was established by feeding rats a high-fat diet(feeding for 8 weeks).After successful modeling,the modeling group was randomly divided into the model,electroacupuncture,mTORC1 inhibitor,and electroacupuncture+mTORC1 agonist groups,with six rats in each group.Except for the blank group,all other rats were fed with high fat diet.Rats in the electroacupuncture and electroacupuncture+mTORC1 agonist groups received electroacupuncture intervention at bilateral"Fenglong"(ST40)acupoints(dilatational wave 2 Hz/100 Hz,current intensity 1 mA)for 30 min once daily.Rats in the mTORC1 inhibitor group received intraperitoneal injections of the mTORC1 inhibitor,rapamycin(2 mg/kg),once daily.Rats in the electroacupuncture+mTORC1 agonist group received intraperitoneal injections of the mTORC1 agonist MHY1485(10 mg/kg)once daily.The interventions were administered for five consecutive days per week for 4 weeks.Upon completion of the intervention,the following analyses were performed:serum contents of total cholesterol(TC),triglycerides(TAG),low-density lipoprotein cholesterol(LDL-C),high-density lipoprotein cholesterol(HDL-C),free fatty acids(FFA),alanine aminotransferase(ALT),and aspartate aminotransferase(AST)were measured using a fully automated biochemical analyzer.Hepatic histopathological changes and lipid deposition were observed using hematoxylin-eosin and oil red O staining.The liver condition was observed and the liver index was calculated.Hepatic TC and TAG levels were measured using an enzyme-linked immunosorbent assay.The ultrastructure of the liver tissue was observed using transmission electron microscopy,and the mean fluorescence intensity of perilipin 2(PLIN2)and microtubule-associated protein 1 light chain 3(LC3)-Ⅱ in the liver tissue was detected using immunofluorescence.Protein expression of LC3-Ⅱ/LC3-Ⅰ,phosphorylated mammalian target of rapamycin(p-mTOR)/mTOR,and mTORC1 in liver tissue was detected using Western blotting.Results Compared to the blank group,the model group rats showed increased serum TC,TAG,LDL-C,ALT,AST,and FFA levels,along with decreased HDL-C levels(P<0.05).The liver index and hepatic TC and TAG levels were also elevated(P<0.05).Histological examination of liver tissue revealed substantial lipid accumulation,numerous lipid droplets within hepatocytes,abnormal mitochondrial morphology,and scarce autophagic vacuole.The mean fluorescence intensity of PLIN2 increased,whereas that of LC3-Ⅱ decreased(P<0.05).Additionally,the LC3-Ⅱ/LC3-Ⅰ ratio was reduced,whereas the p-mTOR/mTOR ratio and mTORC1 protein expression were increased(P<0.05).Compared to the model group,rats in the mTORC1 inhibitor and electroacupuncture groups exhibited decreased serum TC,TAG,LDL-C,ALT,AST,and FFA levels(P<0.05),along with a reduced liver index and hepatic TC and TAG levels(P<0.05).Histological examination showed markedly attenuated lipid accumulation and visible autophagic vacuole in the hepatocytes.The mean fluorescence intensity of PLIN2 decreased,whereas that of LC3-Ⅱ increased(P<0.05).Moreover,the LC3-Ⅱ/LC3-Ⅰ ratio increased,whereas the p-mTOR/mTOR ratio and mTORC1 protein expression decreased(P<0.05).In comparison with both the electroacupuncture and mTORC1 inhibitor groups,the electroacupuncture+mTORC1 agonist group demonstrated increased serum TAG,TC,LDL-C,ALT,AST,and FFA levels(P<0.05)as well as elevated liver index and hepatic TC and TAG levels(P<0.05).Liver tissues exhibited aggravated lipid deposition and absence of autophagic vacuole in liver cells.The mean fluorescence intensity of PLIN2 was enhanced,whereas that of LC3-Ⅱ was reduced(P<0.05).Furthermore,the LC3-Ⅱ/LC3-Ⅰ ratio decreased,and the p-mTOR/mTOR ratio and mTORC1 protein expression increased(P<0.05).Conclusion Electroacupuncture at"Fenglong"(ST40)may improve blood lipid levels in hyperlipidemic rats by inhibiting mTORC1 and promoting hepatocyte lipophagy.

Objective To explore the mechanism of electroacupuncture in alleviating hyperlipidemia in a rat model by modulating mammalian target of rapamycin complex 1(mTORC1)-mediated lipophagy in hepatocytes.Methods A total of 30 SD rats were randomly divided into blank(n=6)and modeling groups(n=24)using the random number table method.A hyperlipidemic rat model was established by feeding rats a high-fat diet(feeding for 8 weeks).After successful modeling,the modeling group was randomly divided into the model,electroacupuncture,mTORC1 inhibitor,and electroacupuncture+mTORC1 agonist groups,with six rats in each group.Except for the blank group,all other rats were fed with high fat diet.Rats in the electroacupuncture and electroacupuncture+mTORC1 agonist groups received electroacupuncture intervention at bilateral"Fenglong"(ST40)acupoints(dilatational wave 2 Hz/100 Hz,current intensity 1 mA)for 30 min once daily.Rats in the mTORC1 inhibitor group received intraperitoneal injections of the mTORC1 inhibitor,rapamycin(2 mg/kg),once daily.Rats in the electroacupuncture+mTORC1 agonist group received intraperitoneal injections of the mTORC1 agonist MHY1485(10 mg/kg)once daily.The interventions were administered for five consecutive days per week for 4 weeks.Upon completion of the intervention,the following analyses were performed:serum contents of total cholesterol(TC),triglycerides(TAG),low-density lipoprotein cholesterol(LDL-C),high-density lipoprotein cholesterol(HDL-C),free fatty acids(FFA),alanine aminotransferase(ALT),and aspartate aminotransferase(AST)were measured using a fully automated biochemical analyzer.Hepatic histopathological changes and lipid deposition were observed using hematoxylin-eosin and oil red O staining.The liver condition was observed and the liver index was calculated.Hepatic TC and TAG levels were measured using an enzyme-linked immunosorbent assay.The ultrastructure of the liver tissue was observed using transmission electron microscopy,and the mean fluorescence intensity of perilipin 2(PLIN2)and microtubule-associated protein 1 light chain 3(LC3)-Ⅱ in the liver tissue was detected using immunofluorescence.Protein expression of LC3-Ⅱ/LC3-Ⅰ,phosphorylated mammalian target of rapamycin(p-mTOR)/mTOR,and mTORC1 in liver tissue was detected using Western blotting.Results Compared to the blank group,the model group rats showed increased serum TC,TAG,LDL-C,ALT,AST,and FFA levels,along with decreased HDL-C levels(P<0.05).The liver index and hepatic TC and TAG levels were also elevated(P<0.05).Histological examination of liver tissue revealed substantial lipid accumulation,numerous lipid droplets within hepatocytes,abnormal mitochondrial morphology,and scarce autophagic vacuole.The mean fluorescence intensity of PLIN2 increased,whereas that of LC3-Ⅱ decreased(P<0.05).Additionally,the LC3-Ⅱ/LC3-Ⅰ ratio was reduced,whereas the p-mTOR/mTOR ratio and mTORC1 protein expression were increased(P<0.05).Compared to the model group,rats in the mTORC1 inhibitor and electroacupuncture groups exhibited decreased serum TC,TAG,LDL-C,ALT,AST,and FFA levels(P<0.05),along with a reduced liver index and hepatic TC and TAG levels(P<0.05).Histological examination showed markedly attenuated lipid accumulation and visible autophagic vacuole in the hepatocytes.The mean fluorescence intensity of PLIN2 decreased,whereas that of LC3-Ⅱ increased(P<0.05).Moreover,the LC3-Ⅱ/LC3-Ⅰ ratio increased,whereas the p-mTOR/mTOR ratio and mTORC1 protein expression decreased(P<0.05).In comparison with both the electroacupuncture and mTORC1 inhibitor groups,the electroacupuncture+mTORC1 agonist group demonstrated increased serum TAG,TC,LDL-C,ALT,AST,and FFA levels(P<0.05)as well as elevated liver index and hepatic TC and TAG levels(P<0.05).Liver tissues exhibited aggravated lipid deposition and absence of autophagic vacuole in liver cells.The mean fluorescence intensity of PLIN2 was enhanced,whereas that of LC3-Ⅱ was reduced(P<0.05).Furthermore,the LC3-Ⅱ/LC3-Ⅰ ratio decreased,and the p-mTOR/mTOR ratio and mTORC1 protein expression increased(P<0.05).Conclusion Electroacupuncture at"Fenglong"(ST40)may improve blood lipid levels in hyperlipidemic rats by inhibiting mTORC1 and promoting hepatocyte lipophagy.