JAK2 expression in myocardial tissue of rats after exercise preconditioning and exhaustive exercise injury / 中国组织工程研究

ABSTRACT

BACKGROUND:Several studies have demonstrated that JAK2 kinase plays an important role in myocardial protection by ischemic preconditioning and medicine preconditioning. OBJECTIVE:To investigate the effects of exercise preconditioning on JAK2 mRNA and protein expression in the rat heart and the underlying mechanism of action. METHODS:SD rats were randomly divided into control, exhaustive, exercise preconditioning, and exercise preconditioning + AG490 groups. Rats in the control and exhaustive groups were fed routinely for 3 days. Rats in the exercise preconditioning and exercise preconditioning + AG490 groups were subjected to intermittent treadmil exercise for 3 successive days to establish exercise preconditioning animal models. Rats in the exercise preconditioning + AG490 group were intraperitonealy injected with JAK2 inhibitor AG490 at 10 minutes before exercise preconditioning. After 3 days, rats in the exhaustive, exercise preconditioning, and exercise preconditioning + AG490 groups were subjected to exhaustive treadmil exercise. Serum levels of lactate dehydrogenase and creatine kinase isoenzyme were determined. JAK2 mRNA and protein expression in the rat myocardial tissue was detected by real-time fluorescent quantitative PCR and immunohistochemistry.RESULTS AND CONCLUSION:Compared with the control group, serum levels of actate dehydrogenase and creatine kinase isoenzyme were increased, and JAK2 mRNA and protein expression in the myocardial tissue was significantly increased in the exhaustive group (P < 0.05). Compared with the exhaustive group, serum levels of actate dehydrogenase and creatine kinase isoenzyme were decreased (P < 0.05), while JAK2 mRNA and protein expression in the myocardial tissue was increased in the exercise preconditioning group (P < 0.05). Compared with the exercise preconditioning group, serum levels of actate dehydrogenase and creatine kinase isoenzyme were increased (P < 0.05), while JAK2 mRNA and protein expression in the myocardial tissue was decreased in the exercise preconditioning + AG490 group (P < 0.05). The results confirm that exercise preconditioning plays its cardioprotective role through activating JAK/STAT signaling pathway, up-regulating the expression of JAK2 mRNA and protein in the cardiac tissue and aleviating myocardial ischemia injury.