Exercise preconditioning for myocardial injury in rats after exhaustive exercise based on Rho/ROCK pathway / 中国组织工程研究

ABSTRACT

BACKGROUND; At present, the mechanism of exercise preconditioning for myocardial protection has not been fully elucidated. It is reported that Rho/ROCK pathway plays a key role in cardiovascular disease. Whether exercise preconditioning adapts to the myocardium through the Rho/ROCK signaling pathway remains to be studied. OBJECTIVE: To investigate the role of exercise preconditioning in rats with myocardial injury after exhaustive exercise. METHODS: Sixty male Sprague-Dawley rats of 5 weeks old were randomly divided into three groups Control group, simple exhaustive exercise group (EE group), and exercise preconditioning group after exhaustive exercise (EP+EE group). At 1 hour after modeling, a serum sample from each rat was taken for biochemical analysis. The levels of aspartate aminotransferase, phosphocreatine kinase, and lactate dehydrogenase were detected. Myocardial tissue samples from each rat were taken for pathological observation using hematoxylin-alkaline reddish-picric acid staining. TUNEL method was used to observe apoptosis in the myocardial tissue. The levels of tumor necrosis factor-a and interleukin-10 in the myocardial tissue were detected by ELISA. The expression of RhoA, ROCK1, ROCK2, Bax, and Bcl-2 protein was analyzed by western blot. RESULTS AND CONCLUSION: The levels of aspartate aminotransferase, phosphocreatine kinase, and lactate dehydrogenase of the EE group were significantly higher than those of the control group (P < 0.05). The levels of aspartate aminotransferase, phosphocreatine kinase, and lactate dehydrogenase of the EP+EE group were significantly lower than those of the EE group (P < 0.05). The boundary of cardiomyocytes was unclear in the EE group, in which there were more plaque-like or flaky red-like areas as well as more obvious ischemia-anoxia changes as compared with the control group. Some cardiomyocytes presented with unclear boundary in the EP+EE group with some plaque-like brilliant red-like areas, and the degree of ischemia and anoxemia was significantly lower in the EP+EE group than the EE group. The apoptotic index value of the EE group was significantly higher than that of the control group, and the apoptotic index value of the EP+EE group was significantly lower than that of the EE group (P< 0.05). The tumor necrosis factor-a and interleukin-10 levels in the EE group were significantly higher than those in the control group (P < 0.05). The tumor necrosis factor-a and interleukin-10 levels in the EP+EE group were significantly lower than those in the EE group (P < 0.05). The Bcl-2/Bax of the EE group was significantly lower than that of the control group (P < 0.05). The Bcl-2/Bax of the EP+EE group was significantly higher than that of the EE group (P < 0.05). The levels of RhoA, ROCK1 and ROCK2 in the EE group were significantly higher than those in the control group. The levels of RhoA, ROCK1 and ROCK2 in the EP+EE group were significantly lower than those in the EE group (P < 0.05). These findings indicate that exercise preconditioning has a protective effect against myocardial injury and improves cardiac function in rats. The mechanism may be related to the Rho/ROCK pathway.