ABSTRACT
OBJECTIVE: To observe the effect of moxibustion on cardiac function and expression of myocardial tumor suppressor protein p53, mammalian target of rapamycin (mTOR) and phosphorylated(p)-mTOR (excessive autophagy-associated proteins of cardiomyocytes) in rats with chronic heart failure (CHF), so as to explore its mechanisms underlying improvement of CHF. METHODS: SD rats were divided into blank control (n＝11), model(n＝8), autophagy activator (n＝8), autophagy inhibitor (n＝9) and moxibustion(n＝9) groups. The CHF model was established by i．p. injection of Doxorubicin Hydrochloride (DOX, 1 mg/mL, 1-4 mg/kg) every other day. Moxibustion was applied to bilateral "Feishu" (BL13) and "Xinshu" (BL15) for 20 min, 5 times a week for 3 weeks. Rats of the autophagy activator group received gavage of Rapamycin (RAPA, 2 mg/kg) and those of the autophagy inhibitor group received i．p. injection of Methyladenine (3-MA, 15 mg/kg) 5 times a week for 3 weeks after successful modeling. The heart weight and body weight were measured to calculate heart mass index (HW/BW＝heart weight ÷ body weight). Cardiac output (CO) and heart rate (HR) were measured by using a cardiac function meter. Serum N-terminal pro-brain natriuretic peptide (NT-pro BNP) content was assayed by using ELISA, and the expression of myocardial p53, p-mTOR and mTOR proteins was examined by Western blot. RESULTS: (1) Compared with the blank control group, the HR, HW/BW, NT-pro BNP content and p53 expression levels were significantly increased (P<0.01), and the CO and ratio of p-mTOR/mTOR were significantly decreased in the model group (P<0.01). (2) Compared with the model group, the HR, HW/BW and NT-pro BNP content of the autophagy inhibitor and moxibustion groups were significantly decreased (P<0.01, P<0.05), and CO and p-mTOR/mTOR ratio were significantly increased in both autophagy inhibitor and moxibustion groups (P<0.01). (3) Compared with the autophagy activator group, the levels of HR, HW/BW, NT-pro BNP and p53 in the autophagy inhibitor and moxibustion groups were significantly lower (P<0.01), and those of CO and p-mTOR/mTOR levels were significantly higher (P<0.01). CONCLUSION: Moxibustion, similar to the autophagy inhibitor, has a protective action on myocardium in CHF rats, which is possible by preventing over expression of myocardial autophagy-associated proteins during CHF.
ABSTRACT
OBJECTIVE: To observe the effect of electroacupuncture (EA) and moxibustion (Moxi) pretreatment on myocardial pathological and structural changes and expression of autophagy related protein LC 3 Ⅰ/Ⅱ and Beclin 1 in rats with myocardial ischemia-reperfusion injury (MI/RI), so as to explore their mechanisms underlying improving MI/RI. METHODS: Forty SD rats were randomly divided into sham operation, model, ischemic preconditioning (IP), EA and Moxi groups (n＝8 in each group). EA (10 Hz/50 Hz，1 mA) or Moxi (ignited moxa stick) was respectively applied to bilateral "Neiguan"(PC 6) for 20 min, once daily for 7 days. The MI/RI model was established by occlusion of the anterior descending branch of the left coronary artery for 40 min, followed by reperfusion for 60 min. The left ventricular (LV) tissue samples were collected and analyzed for pathological (H.E. staining) and ultrastructural changes, for myocardial apoptosis (apoptotic index＝ number of apoptotic cells/total number of cardiomyocytes×100%) with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) method, and for the expression of LC 3 and Beclin 1 in myocardial cells with Western blot. RESULTS: Following MI/RI, H．E. staining revealed a disorder of arrangement of cardiomyocytes with vague border, inflammatory cell infiltration, intracellular swelling with bleeding, necrosis and dissolution of partial striated muscles of the left ventricle under light microscope, and dual staining of Uranyl acetate and leadnitrate showed atrophy, arrangement disorder, dissolution, necrosis, and interstitial edema of partial myocardial fibers, mitochondrial structural disorder, vacolation, and large body of autophagosomes with bilayers, etc. in ultrastructure, which was relatively lighter in both EA and Moxi groups. The apoptosis index, expression levels of myocardial LC 3 Ⅱ and Beclin 1 and the ratio of LC 3 Ⅱ/LC 3 Ⅰ were significantly higher in the model group than those in the sham operation group (P<0.01), but the expression level of LC 3 Ⅰ was considerably down-regulated in the model group relevant to the sham operation group (P<0.01). Following the intervention and MI preconditioning, the increased apoptosis index and expression levels of LC 3Ⅱ and Beclin 1 proteins and the ratio of LC 3Ⅱ/LC 3 Ⅰ were obviously down-regulated in the IP, EA and Moxi groups relevant to the model group (P<0.01), and the decreased expression of LC 3 Ⅰ protein was up-regulated obviously in the 3 treatment groups (P<0.05，P<0.01). The effects of EA were significantly superior to those of IP and Moxi groups in down-regulating apoptosis index and expression of LC 3 Ⅱ and Beclin 1 and the ratio of LC 3 Ⅱ/LC 3 Ⅰ and in up-regulating expression of LC 3 Ⅰ (P<0.05, P<0.01). CONCLUSION: Both EA and Moxi preconditioning of PC 6 have a protective effect on ischemic myocardium in MI/RI rats, which is probably related to their effects in regulating expression of myocardial autophagy proteins as LC 3 Ⅰ/Ⅱ and Beclin 1.