Author(s): GAN, C., Institution: GUIZHOU INSTITUTE OF SPORT SCIENCE, Country: CHINA, Abstract-ID: 2048

INTRODUCTION:
The protective effect of exercise preconditioning in myocardial ischemia-reperfusion injury has been confirmed, but its specific molecular mechanism has not been fully elucidated. There is no related study on whether FAM134B is involved in the protective effect of exercise preconditioning on reperfusion myocardium. This study explored the effect of exercise preconditioning on endoplasmic reticulum autophagy and the mechanism of FAM134B in mice with myocardial ischemia-reperfusion, in an attempt to provide basis for clinical application and exercise practice.
METHODS:
The models of exercise preconditioning and in vivo myocardial ischemia-reperfusion in mice were established respectively. They were divided into four groups: sham operation group, ischemia-reperfusion group, exercise preconditioning + sham operation group, exercise preconditioning + ischemia-reperfusion group. After the intervention of exercise preconditioning, 60 8-week-old SPF male C57BL/6J mice were randomly divided into two groups: control group and exercise group. The control group was routinely fed for 9 weeks; the exercise group was given 1 week of adaptive exercise, followed by 8 weeks of moderate intensity treadmill aerobic exercise preconditioning (6 days / week, 60min/ days, slope 0 °). The exercise load was determined by the incremental load treadmill test, and the exhaustion speed was used as the basis for determining the maximum load. The intensity of exercise preconditioning was 60-65% of the maximum intensity (16-20m/min). The model of myocardial ischemia-reperfusion was made in mice after exercise preconditioning. The morphology of cardiomyocytes was observed by HE staining, the infarct size was observed by TTC staining. Autophagy protein LC3 and endoplasmic reticulum autophagy receptor FAM134B were detected by qPCR and Western blot.
RESULTS:
The myocardial ischemia-reperfusion model was established successfully. (1)The changes of the morphology and function of the central muscle in the myocardial protective effect of exercise preconditioning. Compared with I/R group, myocardial myofibril was neatly arranged, myocardial interstitial edema was significantly alleviated, inflammatory cell infiltration and small focus necrosis were occasionally seen in E+I/R group. The percentage of myocardial infarct area in E+I/R group were significantly lower than those in I/R group (P < 0.05). (2)The expression of endoplasmic reticulum autophagy protein in the cardioprotective effect of exercise preconditioning. The expression of FAM134B mRNA and protein in E+I/R group was significantly higher than that in I/R group, while the expression of LC3II/I mRNA and protein was significantly decreased (P < 0.05).
CONCLUSION:
In the mouse myocardial ischemia-reperfusion model, the expression of FAM134B was down-regulated. 8-week exercise preconditioning played a protective role in mice myocardial ischemia-reperfusion injury, which was related to endoplasmic reticulum autophagy mediated by FAM134B.