Continuous and Interval Exercise Intervention on the Expression of Myocardial mi RNAs Related to Angiogenesis and Activitation of EGFL7/mi R126-PIK3R2/SPRED1 on Protecting the Hearts of MI Rats

Objectives: This study was carried out to investigate the continuous and interval exercise intervention on the expression of myocardial mi RNAs related to angiogenesis and possible mechanism. Methods: 40 three-month-old male SD rats were randomly divided into four groups:sham-operated group (S) , myocardial infarction group (MI) , MI with continuous exercise group (MCE) and MI with interval exercise group (MIE) . MI model was induced by ligation of the left anterior descending (LAD) coronary artery. After five days' adaptive training (15m/min, 30min/d×5d) , rats in MCE group performed continuous exercise for 64min/d, 5d/wk×8wk at the speed of16m/min (50% ~60% V̇O2 max) , and MIE intervals alternated between 4min at 25m/min (85%~90% V̇O2 max) and 3min at 15m/min (50%~60% V̇O2 max) for 49min/d, 5d/wk×8wk. Cardiac function was measured the next day after 8wk training. CFV was analyzed through Masson' trichrome staining; CD31 and α-SMA were evaluated by immunohistochemistry. The expression of mi RNAs related to angiogenesis, egfl7、pik3r2, spred1 were determined by RT- q PCR, while PIK3R2, SPRED1, VEGF were measured by Western Blotting. Results: Compared with S group, cardic function in MI was impaired with mi R- 222'upregulation and mi R- 126'downregulation; Compared with MI group, levels of mi R-17-5p and mi R-126 increased in MIE; meanwhile, in either MIE or MCE, positive granules of CD31 and α- SMA, VEGF, egfl7 m RNA were elevated andmi R-126 was found to have a highly positive correlation with egfl7 m RNA. in addition, the protein levels of PIK3R2、SPRED1 and their m RNA decreased, and rats in MIE group shows better performance than their counterparts in MCE group. Conclusions: Interval exercise training promotes an increase in the expression of mi R-126 and mi R-17-5p, and an even bigger change rate in mi R-126. Continuous and interval exercise could suppress the protein expression of PIK3R2/SPRED1 through the activation of EGFL7/mi R126- PIK3R2/SPRED1, promote angiogenesis in peri- infarct zone, all of which result in the protection of the MI hearts in the end. The protective effect of interval exercise was better than continuous exercise.