ABSTRACT
Objective:To observe the effects of electroacupuncture preconditioning on the autophagy-related pathway protein kinase B (Akt)/mammalian target of rapamycin (mTOR) in myocardial tissue of rats with myocardial ischemia reperfusion injury (MIRI); To investigate the protective mechanism of "Neiguan"(PC 6) on myocardial injury.Methods:Totally 48 SD rats were randomly divided into blank group, sham-operation group, model group and Neiguan group ( n=12 in each group). The Neiguan group was applied to bilateral "Neiguan"(PC 6) by electroacupuncture for 30 min, once daily for consecutive 7 days before model replication. Except in the blank group, the MIRI model was established by ligation of the descending anterior branch of the left coronary artery in the rest groups after the intervention. The histomorphological changes in the myocardium of the rats were observed by HE staining, and the expression levels of Akt, phosphorylated Akt (p-Akt), mTOR and phosphorylated mTOR (p-mTOR) in the myocardium were measured by protein immunoblotting. The ratio of p-Akt/Akt and p-mTOR/mTOR was calculated. Results:In the blank group, the myocardial fibres were arranged regularly and neatly, and no inflammatory cell infiltration or haemorrhage was seen in the interstitium; in the sham-operation group, the arrangement of myocardial fibers was slightly irregular, no rupture was found, and a small amount of myocardial fiber gap was slightly enlarged; in the model group, the distribution of myocardial fibers was disordered, hypertrophic cardiomyocytes increased, some mitochondria were red and swollen or the outer membrane was ruptured, and inflammatory infiltration and hemorrhage were seen in the interstitium; the extent of myocardial lesions in the Neiguan group was less than that in the model group, with a small amount of interstitial hemorrhage and inflammatory cell infiltration. There was no statistical significance in the levels of Akt and mTOR in the myocardial tissues of the rats in each group ( P>0.05); compared with the sham-operation group, the levels of p-Akt, p-mTOR and p-Akt/Akt, p-mTOR/mTOR in the model group decreased ( P<0.01); compared with the model group, the levels of p-Akt, p-mTOR and p-Akt/Akt, p-mTOR/mTOR in the Neiguan group increased ( P<0.01). Conclusion:Electroacupuncture preconditioning may inhibit excessive autophagy by activating the Akt/mTOR pathway in cardiomyocytes of MIRI rats, thereby exerting a protective effect on the myocardium.