| Myocardial ischemia causes irreversible myocardial necrosis, decrease of functional myocardial cell,β1 adrenal receptor(β1-AR) expression and ATP synthesis. All these changes will finally reduce cardiac systolic function. Myocardial ischemia is an important factor of cardiovascular death. Resveratrol, a kind of anthraquinone terpenoids, is extracted from the root stalks of Polygonum cuspidatum Sieb. et Zucc. It has a variety of functions, such as anti-inflammation, anti-oxidation, anti-apoptosis, anti-arteriosclerosis, anti-senescence, and anti-insulin-resistance. However, there have been no related reports about whether resveratrol is effective on the development and prognosis of heart failure induced by myocardial infarction. ATP decreasing can activate AMPK, and researchs have shown that activated AMPK can improve energy metabolization, alleviate heart failure, resveratrol can activate AMPK by stimulating SIRT1, all these indicate that resveratrol can alleviate heart failure. Restoringβ1-AR expression and sensitivity is one of the important measures for the treatment of heart failure, researchs have shown that PI3K activation is the reason ofβ1-AR expression decreasing; and SIRT1 can increase insulin system sensitivity by inhibiting PI3K activity, all these indicate that resveratrol can restoreβ1-AR expression by activating SIRT1. So in Part I of my paper, I studied the protective function of resveratrol in treating heart failure rats and its effect on mortality of rats from myocardial infarction. Next, through perfusion of isolated hearts of SIRT1(+/-) mice, I recorded the value of LVPmax, +dP/dTmax, -dP/dTmax, and studied the effect of SIRT1 gene on cardiac systolic function, and its regulation effect on AMPK andβ1 adrenocept expression. Last, through stimulating H9c2 cells with different concentrations of resveratrol, I studied the regulatory role of resveratrol on AMPK andβ1 adrenocept expression,using nicotinamide to inhibit the activity of SIRT1 on overexpression SIRT1 H9c2 cells, I studied the effect of SIRT1 on AMPK andβ1 adrenocept expression.Part I: Influence of resveratrol on cardiac function and mortality of rats with myocardial infarctionAims: The purpose was to identify the influence of resveratrol upon heart function and mortality of rats with myocardial infarction and the regulation effect of resveratrol on the expression of AMPK andβ1 adrenoceptor of myocardium.Methods: 22 rat models of myocardial infarction were set up by ligating left anterior descending artery(LAD)whereas sham group rats undergo chest operation without LAD ligation. The sham group (n=10) and the heart failure group (n=11) were given normal dietary; the treatment group (n=11) was given resveratrol 2.5mg/kg/d orally. After the 16 weeks of feeding, echocardiography, AMPK,β1 adrenoceptor expression were examined.Results: Compared with the heart failure group, Resveratrol treatment group demonstrated a sharp decrease in mortality (P<0.01) and a significant increase in left ventricular ejection fraction (LVEF) (46.84±6.06 vs 34.44±2.13 %, P<0.01). The heart failure group had a decreased expression ofβ1 adrenoceptor compared with the sham group (P<0.01), while the treatment group had an increased expression ofβ1 adrenoceptor compared with the heart failure group (P<0.01). Compared with the sham group, the heart failure group and the treatment group expreienced increased AMPK expression (P<0.05, P<0.01 respectively) while the treatment group had a significent increase compared with the heart failure group (P<0.05).Conclusions: Resveratrol can reduce mortality and improve heart function after myocardial infarction. It can increase AMPK andβ1 adrenoceptor expression.Part II Effect of SIRT1 gene on cardiac function and life in miceAims: To observe effect of SIRT1 gene on cardiac function and life in mice and study influence of SIRT1 gene on myocardial express ofβ1 adrenal receptors and AMPK.Methods: SIRT1(+/-) mice were bred and identified. Heart function was examined on Langendorff perfused hearts of SIRT1(+/-) (n=4) and wild type(WT) (n=5) mice. Theβ1 adrenoceptor and AMPK expression in SIRT1(+/-) (n=8) and WT(n=7) mice was examined by Western blotting. Days of SIRT1(+/-) (n=3) and WT(n=3) mice life were recorded.Results: 25 SIRT1 (+/-) mice were breed and identified. Compared with wild type, theβ1 adrenoceptor and AMPK expression decreased significantly in SIRT1(+/-) mice hearts (P<0.01). Compared with wild type, LVPmax, +dP/dTmax, -dP/dTmax in Langendorff perfused hearts were significantly reduced in SIRT1(+/-) mice (111.04±13.97 vs 141.90±6.63mmHg, 2944.33±461.02 vs 7122.73±1083.12 mmHg/s, 2081.72±323.81 vs 4807.48±789.79 mmHg/s, P<0.01 respectively). Life of SIRT1(+/-) mice is shorter than that of WT mice (P<0.01).Conclusions: Knock out SIRT1 gene significantly reduced mice life and decreased cardiac systolic and diastolic function in mice, the mechanism of which may be the reducing of expression ofβ1 adrenal receptor and AMPK. These results indicate that SIRT1 may improve heart systolic and diastolic function via increasingβ1 adrenal receptor and AMPK expression.Part III Resveratrol regulatesβ1 adrenoceptor and AMPK expression via activation of SIRT1 in H9c2 cellsAims: The principal objective of this part was to study the effect of resveratrol onβ1-AR and AMPK expression via activation of SIRT1 in H9c2 cells.Methods: After H9c2 cells had been cultivated with different concentrations of resveratrol (0, 10, 25, 50, 100 uM) for 24 hours, cells were collected for detecting SIRT1,β1-AR and AMPK expressions by Western blotting. We constructed the plasmid with overexpression of SIRT1 gene, transfected this plasmid to H9c2 cells, established SIRT1 overexpression H9c2 cell line and measured the expression ofβ1 adrenal receptor and AMPK. The expression of SIRT1,β1-AR and AMPK was also tested in H9c2 cells and SIRT1 overexpression H9c2 cells cultivated in different concentrations of nicotinamide (0, 10, 20, 40 mM).Results: 1. Expression of SIRT1,β1 adrenoceptor and AMPK was significantly increased in H9c2 cells cultivated with resveratrol (50, 100 uM) for 24 hours as compared with control H9c2 cells (P<0.01).2.β1 adrenoceptor and AMPK expressions were significantly increased in H9c2 cells by SIRT1 overexpression (P<0.01).3., Having inhibited activities of SIRT1 with different concentrations of NAM for 24 hours in overexpression SIRT1 H9c2 cell line, AMPK expression was significantly reduced in groups of NAM (20, 40 mM) compared with control (P<0.01,respectively).β1 adrenoceptor was also reduced significantly in group of NAM (20 mM) (P<0.05) and in group of NAM (40 mM) (P<0.01).Conclusions:β1 adrenoceptor and AMPK expression was increased in H9c2 cells by overexpression SIRT1 gene, and resveratrol might regulateβ1 adrenoceptor and AMPK expression through activating SIRT1 in H9c2 cells.β1 adrenoceptor and AMPK expression decreased with NAM inhibiting activation of SIRT1 in overexpression SIRT1 H9c2 cell line. These results indicated that activated SIRT1 increased the number ofβ1-AR and the activity of AMPK, and resveratrol improved heart function via activation of SIRT1. |
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