Effect of electroacupuncture preconditioning on myocyte apoptosis in myocardial ischemia-reperfusion injury rats based on FXR/SHP pathway

Abstract

To observe the effect of electroacupuncture (EA) preconditioning on left-cardiac function, contents of serum TNF-α and IL-6 and expression of myocardial farnesoid X receptor(FXR), small heterodimer partner (SHP), apoptosis inducing factor (AIF) and heat shock proteins 70 (HSP70) genes in myocardial ischemia-reperfusion injury (MIRI) rats, so as to explore its mechanisms underlying improvement of ischemic myocardial injury. Forty male Wistar rats were randomly divided into normal control, sham operation, MIRI model and EA pretreatment groups, with 10 rats in each group. Rats of the sham operation group received exposure of the thorax and heart. The MIRI model was established by occlusion of the anterior descending branch of the left coronary artery (LAD). EA (2 Hz/100 Hz and 1 mA) was applied to bilateral "Neiguan" (PC6), "Zusanli" (ST36) and "Guanyuan" (CV4) for 20 min, once a day for 7 days. The left ventricular end-diastolic pressure (LVEDP), left ventricular systolic pressure (LVSP)and maximal rates of rise and fall of left ventricular pressure (±dp/dtmax) were detected, the contents of serum TNF-α and IL-6 were detected by using enzyme-linked immunosorbent assay (ELISA), and the expression of FXR, SHP, AIF and HSP70 apoptotic genes in the myocardial tissue were measured by fluorescent quantitative RT-PCR. Compared with the normal control group, the LVEDP, contents of serum TNF-α and IL-6, and the expression levels of myocardial FXR, SHP, AIF and HSP70 mRNAs were significantly increased (P<0.05), while LVSP and ±dp/dtmax levels were obviously decreased in the model group (P<0.05). In comparison with the model group, MIRI-induced increases of LVEDP, TNF-α and IL-6 contents, and FXR, SHP and AIF mRNA expression and decreases of ±dp/dtmax and LVSP levels were reversed(P<0.05), except HSP70 mRNA expression with significantly increased (P<0.05) in the EA pretreatment group. EA pretreatment can protect the left ventricular function of the ischemic heart in MIRI rats, which may be related to its effects in reliving peripheral inflammation and regulating the expression levels of apoptosis-related factors FXR, SHP, AIF and HSP70 in the myocardium.