Research On The Effect Of Cardiac Hypertrophy By MTOR Signaling In Rats At Different Intensity Training

Objectives:In the current study, we investigated the changing characteristics mTOR signaling of myocardium at different exercise intensity models and revealed the mechanism of roles of myocardium protein synthesis regulated by mTOR signaling pathway.Methods:Adult male SD rats were randomly divided into3groups after adaptive training:sedentary, moderate intensity group and high intensity group. The exercise project was applied by7weeks treadmill at progressive increase exercise intensity. Myocardium and serum were isolated at time point of immediately,6,12and24hrs after exercise. The protein concentration of myocardium was determined by BCA assay. The cTnl was analyzed by ELISA assay. The protein expression of PI3K p85, PI3K p110α, Akt, mTOR, calcineurin and the phosphorylation expression of Akt, GSK3β and mTOR of myocardium were examined by western blotting analysis. HE and HBFP stain were performed to observe the morphology of myocardium.Results:1)The HB/WB index of moderate intensity group and high intensity group were significantly increase than sedentary.2)The peak of cTnI emerged at6h after exercise, still higher than sedentary at24h after exercise.3)In moderate intensity model, the peak of PI3K, Akt, and GSK3β emerged at6h after exercise;The peak of mTOR emerged at12h after exercise. The above protein in high intensity group was not significantly increase.4)Both moderate and high intensity exercise had effect on the protein level of calcineurin. The peak of calcineurin emerged at12h after exercise.Conclusions:1)The degree of cardiac hypertrophy was increase with exercise intensity. The results of morphology and cTnI showed that cardiac hypertrophy induced by moderate intensity exercise is due to physiologic cardiac hypertrophy. Myocardial injury and myocardial ischemia were perfomed by high intensity exercise. This kind of cardiac hypertrophy was defined as pathological cardiac hypertrophy.2)mTOR and calcinurin signaling were activated by moderate intensity exercise to regulate cardiac hypertrophy. mTOR signaling played the the main role in cardiac hypertrophy.3)Calcineurin had a main signaling effect on cardiac hypertrophy induced by high intensity exercise.