Objective: To observe the effects of electroacupuncture (EA) combined with dietary control on liver endoplasmic reticulum stress (ERS) in rats with non-alcoholic fatty liver disease (NAFLD), and to explore the action mechanism of EA on NAFLD.
Methods: Sixty male SD rats were randomly divided into a common diet group (15 rats) and a model group (45 rats, fed with high-fat diet to induce NAFLD model). After model establishment, 10 rats in the common diet group were randomly selected as a control group, and 40 rats in model group were randomly divided into a high-fat diet (HFD) group, a low-fat diet (LFD) group, an EA-1 group and an EA-2 group, 10 rats in each one. From the 2nd day of model establishment, rats in the HFD group and EA-1 group were fed with high-fat diet, while rats in the LFD group and EA-2 group were fed with common diet. Rats in the EA-1 group and EA-2 group were treated with acupuncture at unilateral "Zusanli" (ST 36), "Sanyinjiao" (SP 6) and "Taichong" (LR 3), besides,"Zusanli" (ST 36) and "Sanyinjiao" (SP 6) were connected with EA. The treatment was given once a day, and two sides of acupoints were selected alternatively. Each treatment last 20 min for totally 4 weeks. The rats in the remaining groups were treated with identical fixation method. After treatment, the liver tissues of rats in each group were collected and made into ultra-thin slice to perform transmission electron microscope (TEM) on the endoplasmic reticulum morphology; western blot and real-time PCR method were applied to observe the protein and gene expression of the specific ERS protein, glucose-regulated protein 78 (GRP78).
Results: Under TEM, plenty of rough endoplasmic reticulum in alignment was observed in the cytoplasm of rats in the control group, accompanied with indistinct adhering ribosome; the rough endoplasmic reticulum in the cytoplasm in the HFD group was in expansion and obvious breakage, presenting small vacuoles in irregular arrangement; the expansion of rough endoplasmic reticulum in the LFD group and EA-1 group was relieved without appa-rent breakage and disarrangement; the rough endoplasmic reticulum in the EA-2 group was in alignment without obvious expansion. The protein expression of GRP78 was little in the control group, while the protein and mRNA expression of GRP78 were obviously increased in the remaining groups (all P<0.01). The protein and mRNA expression of GRP78 in the LFD group and EA-1 group were significantly lower than those in the HFD group (all P<0.01); those in the EA-2 group were lower than those in the LFD group and EA-1 group (all P<0.01).
Conclusions: EA effectively improves the liver ERS in NAFLD rats, which can be one of the action mechanisms of EA on NAFLD. In addition, the efficacy is more significant with diet control.
Keywords: diet control; electroacupuncture (EA); endoplasmic reticulum stress (ERS); glucose-regulated protein 78 (GRP 78); non-alcoholic fatty liver disease (NAFLD).