[Effect of electroacupuncture on the SIRT1/HIF-1α/Nrf2 signaling pathway of thoracic aorta in ApoE-/- atherosclerotic mice].

OBJECTIVES

To observe the effect of electroacupuncture(EA) on lipid metabolism, oxidative stress status, pathological morphology of the thoracic aorta and the expression of silent information regulator 1(SIRT1)/hypoxia-inducible factor 1α(HIF-1α)/nuclear factor erythroid 2-related factor 2(Nrf2)signaling pathway in ApoE-/- atherosclerotic(AS)mice, in order to explore the potential mechanism of EA in the prevention and treatment of AS.

METHODS

Ten C57BL/6J mice were assigned as the control group and fed with normal diet, while 42 SPF-grade male ApoE-/- mice were fed with high-fat diet for 12 weeks to establish an AS model. Following successful model induction, the ApoE-/- mice were randomly divided into model, EA, EA+inhibitor, and agonist groups, with 10 mice per group. The EA group received EA at the acupoints "Neiguan"(PC6), "Tongli"(HT5), and "Zusanli"(ST36) using a sparse-dense wave(2 Hz/15 Hz), with a current intensity of 0.3 mA. Each session lasted for 20 min. The EA+inhibitor group received intraperitoneal injections of the SIRT1 inhibitor EX-527(10 mg/kg), with other treatment identical to that in the EA group. The agonist group received intragastric administration of the SIRT1 agonist resveratrol(50 mg/kg). All interventions were administered every other day for 8 weeks. Body weight was measured once every 4 weeks. Serum levels of triglycerides(TG), total cholesterol(TC), high-density lipoprotein cholesterol(HDL-C), and low-density lipoprotein cholesterol(LDL-C), as well as the oxidative stress markers superoxide dismutase(SOD), malondialdehyde(MDA), and glutathione peroxidase(GSH-Px)were measured using colorimetric assays. Histopathological changes in the aorta were assessed using hematoxylin-eosin(HE)staining. The protein and mRNA expression levels of SIRT1, HIF-1α, and Nrf2 in the aorta were analyzed by Western blot and real-time fluorescence quantitative PCR, respectively.

RESULTS

After treatments, compared with the control group, the model group exhibited significantly decreased serum HDL-C, SOD and GSH-Px levels(P<0.01), increased body weight, and serum LDL-C, TC, TG and MDA levels(P<0.01). HE staining showed pathological changes in the vessel wall, including thickened intima with an uneven surface, proliferated endothelial cells forming plaques, inflammatory cell infiltration on the plaque surface, elastic layer structure damage, disordered arrangement of the media smooth muscle layer, and localized foam cells and smooth muscle cell proliferation. Additionally, the protein and mRNA expression levels of SIRT1 and Nrf2 were significantly down-regulated(P<0.01), while those of HIF-1α were up-regulated(P<0.01). Compared with the model group, both the EA and agonist groups showed increased serum HDL-C, SOD and GSH-Px levels(P<0.01, P<0.05), decreased body weight, and serum LDL-C, TC, TG and MDA levels(P<0.01). HE staining revealed improved endothelial morphology, with intact vascular wall, relatively smooth intima, a small amount of endothelial cells abscission, regular arrangement of the smooth muscle layer of the media, no obvious damage in the elastic layer structure, and a small amount of foam cells and smooth muscle cells proliferated.The protein and mRNA expression levels of SIRT1 and Nrf2 were significantly increased(P<0.01, P<0.05), while HIF-1α protein and mRNA expression levels were decreased(P<0.01). Compared with the EA group, the EA+inhibitor group showed decreased serum HDL-C, SOD and GSH-Px levels(P<0.05), increased body weight, and serum LDL-C, TC, TG and MDA levels(P<0.05, P<0.01). HE staining showed that the structural integrity of the vascular wall was damaged, with thickening and injury of the endometrium, endothelial cell proliferation plaques and infiltration of inflammatory cells on the plaque surface, disordered arrangement of smooth muscle layer, and obvious proliferation of smooth muscle cells. The protein and mRNA expression levels of SIRT1 and Nrf2 were significantly reduced(P<0.01, P<0.05), while those of HIF-1α were increased(P<0.01, P<0.05).

CONCLUSIONS

EA may regulate lipid metabolism, alleviate oxidative stress injury, promote vascular intimal repair, and delay the progression of AS in ApoE-/- mice through the activation of the SIRT1/HIF-1α/Nrf2 antioxidant signaling pathway.