康复学报 (Apr 2022)
Effect of Exercise Preconditioning on Autophagy and Apoptosis of Cardiomyocytes in Aged Rats with Myocardial Ischemia Reperfusion Injury
Abstract
ObjectiveTo detect the effects of exercise preconditioning on autophagy protein and apoptosis factor of cardiomyocytes in aged rats with myocardial ischemia reperfusion injury.MethodsA total of 60 aged male SD rats were randomly divided into the control group (Con group), the ischemia/reperfusion group (IR group), the exercise preconditioning+ischemic preconditioning group (EP+IPC group), the exercise preconditioning+ischemic preconditioning+normal saline group (EP+IPC+saline group), the exercise preconditioning+ischemic preconditioning+autophagy inhibitor group (EP+IPC+3-MA group), with 12 cases in each group. The Con group and the IR group did not receive special exercise intervention, the EP+IPC group, the EP+IPC+saline group and the EP+IPC+3-MA group received exercise preconditioning intervention (gradient exercise training was performed on an electric animal experimental treadmill, one time a day, five days a week, continuous training for six weeks). In addition, the EP+IPC+saline group and the EP+IPC+3-MA group were given normal saline and 3-methyladenine inhibitor (3-MA) during reperfusion respectively. The isolated rat myocardial ischemia/reperfusion model was established using the Langendorff in vitro perfusion system. Cardiomyocyte autophagosomes were observed by transmission electron microscope (TEM); cardiomyocyte apoptosis was detected by TUNEL staining; Beclin-1, LC3-Ⅱ, Bax, Caspase-9, Bcl-2, Bcl-XL protein expression levels were detected by Western blot method.Results① TEM observation results: a small amount of autolysosomes were observed in the Con group; more autolysosomes and autophagy vesicles were observed in the IR group; a small amount of autolysosomes were observed in the EP+IPC group; a small number of autophagic vesicles were observed in the EP+IPC+saline group; there wasn't typical autophagic vesicles and lysosomes were observed in the EP+IPC+3-MA group. ② TUNEL positive cell ratio results: only a few TUNEL positive cells were found in the Con group. Compared with the Con group, the ratio of TUNEL positive cells in the IR group increased significantly (P<0.05). Compared with the IR group, the ratio of TUNEL positive cells in the EP+IPC group and the EP+IPC+saline group decreased significantly (P<0.05); compared with the EP+IPC group and the EP+IPC+saline group, the TUNEL positive cell ratio in the EP+IPC+3-MA group increased significantly (P<0.05). ③ Western blot results: compared with the Con group, the expression of Beclin-1, LC3-Ⅱ, Bax and Caspase-9 protein in the IR group significantly increased, the expression of Bcl-2, Bcl-XL protein in the IR group decreased significantly (P<0.05). Compared with the IR group, the expression of Beclin-1, LC3-Ⅱ, Bax and Caspase-9 protein in the EP+IPC group and the EP+IPC+saline group decreased significantly, the expression of Bcl-2, Bcl-XL protein in the IR group increased significantly (P<0.05). Compared with the EP+IPC group and the EP+IPC+saline group, the expression of Beclin-1, LC3-Ⅱ, Bcl-2, Bcl-XL protein in the EP+IPC+3-MA group decreased significantly, the expression of Bax and Caspase-9 protein increased significantly (P<0.05).ConclusionExercise preconditioning can induce myocardial protection of aged rats, reduce cardiomyocytes apoptosis during myocardial ischemia/reperfusion injury, and improve cardiomyocytes morphology. Its mechanism may be that exercise preconditioning can regulate the expression of autophagy related proteins Beclin-1 and LC3-Ⅱ in cardiomyocytes of aged rats, induce the moderate occurrence of autophagy, promote the expression of Bcl-2 and Bcl-XL protein, inhibit the expression of Bax and Caspase-9 protein, and reduce cardiomyocyte apoptosis.
