Effect of aerobic exercise on blood lipid of hyperlipidemia rats and its mechanism / 第二军医大学学报

ABSTRACT

Objective To explore the effect of aerobic exercise on blood lipid of hyperlipidemia rats and its mechanism. Methods A total of 120 healthy male SD rats aged 8 weeks were randomized into normal control group, high-fat diet (HF) group, SBC-115076 group and aerobic exercise group, with 30 rats in each group. The rats in the normal control group were fed with standard diet, and the rats in the other 3 groups were fed with HF to establish hyperlipidemia rat model. The rats in the SBC-115076 group were injected with proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor SBC-115076 (8 mg/kg) once a week for 8 weeks, and the rats in the aerobic exercise group underwent swimming without load 6 days a week for 8 weeks. After 8 weeks, the rats were sacrificed and the blood samples were collected to determine the levels of serum triglyceride (TG), total cholesterol (TC), low-density lipoprotein (LDL) and high-density lipoprotein (HDL). Pathological changes of thoracic aorta were observed using H-E staining. The mRNA and protein expression levels of PCSK9, low-density lipoprotein receptor (LDLR) and sterol regulatory element binding protein (SREBP) in the hepatic tissues were detected by quantitative real-time PCR, Western blotting and immunofluorescence. Results Compared with the normal control group, the levels of serum TG, TC and LDL of the rats were significantly higher in the HF group, and the level of HDL was significantly lower (P<0.01). Compared with the HF group, the levels of serum TG, TC and LDL of the rats were significantly lower in the SBC-115076 and aerobic exercise groups, and the level of HDL was significantly higher (P<0.01). In the HF rats, the aortic tunica intima was thickened and endothelial cells were damaged and exfoliated. Compared with the HF group, the aortic intima thickening was reduced and endothelial damage was less in the aerobic exercise group. Compared with the normal control group, the mRNA and protein expression levels of PCSK9, SREBP1 and SREBP2 were significantly higher in the HF group, and the mRNA and protein expression levels of LDLR were significantly lower (P<0.01). Compared with the HF group, the mRNA and protein expression levels of PCSK9, SREBP1 and SREBP2 were significantly lower, and the mRNA and protein expression levels of LDLR were significantly higher (P<0.01). Conclusion Aerobic exercise can down-regulate the expression of TG, TC and LDL, up-regulate the expression of HDL, and alleviate the intimal thickening of aorta. The mechanism may be related to down-regulating the expression of PCSK9 and SREBPs, thus eliminating the inhibition of LDLR.